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Crameri JJ, Palmer CS, Stait T, Jackson TD, Lynch M, Sinclair A, Frajman LE, Compton AG, Coman D, Thorburn DR, Frazier AE, Stojanovski D. Reduced Protein Import via TIM23 SORT Drives Disease Pathology in TIMM50-Associated Mitochondrial Disease. Mol Cell Biol 2024:1-19. [PMID: 38828998 DOI: 10.1080/10985549.2024.2353652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 05/07/2024] [Indexed: 06/05/2024] Open
Abstract
TIMM50 is a core subunit of the TIM23 complex, the mitochondrial inner membrane translocase responsible for the import of pre-sequence-containing precursors into the mitochondrial matrix and inner membrane. Here we describe a mitochondrial disease patient who is homozygous for a novel variant in TIMM50 and establish the first proteomic map of mitochondrial disease associated with TIMM50 dysfunction. We demonstrate that TIMM50 pathogenic variants reduce the levels and activity of endogenous TIM23 complex, which significantly impacts the mitochondrial proteome, resulting in a combined oxidative phosphorylation (OXPHOS) defect and changes to mitochondrial ultrastructure. Using proteomic data sets from TIMM50 patient fibroblasts and a TIMM50 HEK293 cell model of disease, we reveal that laterally released substrates imported via the TIM23SORT complex pathway are most sensitive to loss of TIMM50. Proteins involved in OXPHOS and mitochondrial ultrastructure are enriched in the TIM23SORT substrate pool, providing a biochemical mechanism for the specific defects in TIMM50-associated mitochondrial disease patients. These results highlight the power of using proteomics to elucidate molecular mechanisms of disease and uncovering novel features of fundamental biology, with the implication that human TIMM50 may have a more pronounced role in lateral insertion than previously understood.
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Affiliation(s)
- Jordan J Crameri
- Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
- The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Catherine S Palmer
- Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
- The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Tegan Stait
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Victorian Clinical Genetics Services, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Thomas D Jackson
- Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
- The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Matthew Lynch
- Neurosciences Department, Queensland Children's Hospital, South Brisbane, Queensland, Australia
- Department of Metabolic Medicine, Queensland Children's Hospital, South Brisbane, Queensland, Australia
- School of Medicine, University of Queensland, St Lucia, Queensland, Australia
| | - Adriane Sinclair
- Neurosciences Department, Queensland Children's Hospital, South Brisbane, Queensland, Australia
| | - Leah E Frajman
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Alison G Compton
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Victorian Clinical Genetics Services, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
| | - David Coman
- Department of Metabolic Medicine, Queensland Children's Hospital, South Brisbane, Queensland, Australia
- School of Medicine, University of Queensland, St Lucia, Queensland, Australia
| | - David R Thorburn
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Victorian Clinical Genetics Services, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
| | - Ann E Frazier
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, Victoria, Australia
| | - Diana Stojanovski
- Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, Australia
- The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
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2
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Sugiyama Y, Murayama K. Acute Encephalopathy Caused by Inherited Metabolic Diseases. J Clin Med 2023; 12:jcm12113797. [PMID: 37297992 DOI: 10.3390/jcm12113797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/22/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
Acute encephalopathy is a critical medical condition that typically affects previously healthy children and young adults and often results in death or severe neurological sequelae. Inherited metabolic diseases that can cause acute encephalopathy include urea cycle disorders, amino acid metabolism disorders, organic acid metabolism disorders, fatty acid metabolism disorders, mutations in the thiamine-transporter gene, and mitochondrial diseases. Although each inherited metabolic disease is rare, its overall incidence is reported as 1 in 800-2500 patients. This narrative review presents the common inherited metabolic diseases that cause acute encephalopathy. Since diagnosing inherited metabolic diseases requires specific testing, early metabolic/metanolic screening tests are required when an inherited metabolic disease is suspected. We also describe the symptoms and history associated with suspected inherited metabolic diseases, the various tests that should be conducted in case of suspicion, and treatment according to the disease group. Recent advancements made in the understanding of some of the inherited metabolic diseases that cause acute encephalopathy are also highlighted. Acute encephalopathy due to inherited metabolic diseases can have numerous different causes, and recognition of the possibility of an inherited metabolic disease as early as possible, obtaining appropriate specimens, and proceeding with testing and treatment in parallel are crucial in the management of these diseases.
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Affiliation(s)
- Yohei Sugiyama
- Department of Metabolism, Chiba Children's Hospital, Chiba 266-0007, Japan
- Department of Pediatrics, Faculty of Medicine, Juntendo University, Tokyo 113-8431, Japan
| | - Kei Murayama
- Center for Medical Genetics, Chiba Children's Hospital, Chiba 266-0007, Japan
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo 113-8431, Japan
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3
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Thompson K, Stroud DA, Thorburn DR, Taylor RW. Investigation of oxidative phosphorylation activity and complex composition in mitochondrial disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 194:127-139. [PMID: 36813309 DOI: 10.1016/b978-0-12-821751-1.00008-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
A multidisciplinary approach to the laboratory diagnosis of mitochondrial disease has long been applied, with crucial information provided by deep clinical phenotyping, blood investigations, and biomarker screening as well as histopathological and biochemical testing of biopsy material to support molecular genetic screening. In an era of second and third generation sequencing technologies, traditional diagnostic algorithms for mitochondrial disease have been replaced by gene agnostic, genomic strategies including whole-exome sequencing (WES) and whole-genome sequencing (WGS), increasingly supported by other 'omics technologies (Alston et al., 2021). Whether a primary testing strategy, or one used to validate and interpret candidate genetic variants, the availability of a range of tests aimed at determining mitochondrial function (i.e., the assessment of individual respiratory chain enzyme activities in a tissue biopsy or cellular respiration in a patient cell line) remains an important part of the diagnostic armory. In this chapter, we summarize several disciplines used in the laboratory investigation of suspected mitochondrial disease, including the histopathological and biochemical assessment of mitochondrial function, as well as protein-based techniques to assess the steady-state levels of oxidative phosphorylation (OXPHOS) subunits and assembly of OXPHOS complexes via traditional (immunoblotting) and cutting-edge (quantitative proteomic) approaches.
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Affiliation(s)
- Kyle Thompson
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David A Stroud
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia; Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - David R Thorburn
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Melbourne, VIC, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia; Mitochondrial Laboratory, Victorian Clinical Genetic Services, Melbourne, VIC, Australia
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.
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4
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Akesson LS, Rius R, Brown NJ, Rosenbaum J, Donoghue S, Stormon M, Chai C, Bordador E, Guo Y, Hakonarson H, Compton AG, Thorburn DR, Amarasekera S, Marum J, Monaco A, Lee C, Chong B, Lunke S, Stark Z, Christodoulou J. Distinct diagnostic trajectories in
NBAS
‐associated acute liver failure highlights the need for timely functional studies. JIMD Rep 2022; 63:240-249. [PMID: 35433172 PMCID: PMC8995841 DOI: 10.1002/jmd2.12280] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 02/22/2022] [Accepted: 03/03/2022] [Indexed: 11/22/2022] Open
Abstract
Variants of uncertain significance (VUS) are commonly found following genomic sequencing, particularly in ethnically diverse populations that are underrepresented in large population databases. Functional characterization of VUS may assist in variant reclassification, however these studies are not readily available and often rely on research funding and good will. We present four individuals from three families at different stages of their diagnostic trajectory with recurrent acute liver failure (RALF) and biallelic NBAS variants, confirmed by either trio analysis or cDNA studies. Functional characterization was undertaken, measuring NBAS and p31 levels by Western blotting, demonstrating reduced NBAS levels in two of three families, and reduced p31 levels in all three families. These results provided functional characterization of the molecular impact of a missense VUS, allowing reclassification of the variant and molecular confirmation of NBAS‐associated RALF. Importantly, p31 was decreased in all individuals, including an individual with two missense variants where NBAS protein levels were preserved. These results highlight the importance of access to timely functional studies after identification of putative variants, and the importance of considering a range of assays to validate variants whose pathogenicity is uncertain. We suggest that funding models for genomic sequencing should consider incorporating capabilities for adjunct RNA, protein, biochemical, and other specialized tests to increase the diagnostic yield which will lead to improved medical care, increased equity, and access to molecular diagnoses for all patients.
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Affiliation(s)
- Lauren S. Akesson
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
- SA Pathology SA Health Adelaide SA Australia
- School of Biomedicine, Faculty of Medicine, Dentistry and Health Sciences University of Adelaide Adelaide Australia Australia
| | - Rocio Rius
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
- Brain and Mitochondrial Research Group Murdoch Children's Research Institute, Royal Children's Hospital Melbourne Victoria Australia
| | - Natasha J. Brown
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
| | - Jeremy Rosenbaum
- Department of Gastroenterology Royal Children's Hospital Melbourne Victoria Australia
| | - Sarah Donoghue
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
- Department of Metabolic Medicine Royal Children's Hospital Melbourne Victoria Australia
| | - Michael Stormon
- Department of Gastroenterology Children's Hospital Westmead Sydney New South Wales Australia
- Discipline of Child & Adolescent Health, Sydney Medical School University of Sydney Sydney New South Wales Australia
| | - Charmaine Chai
- Department of Gastroenterology Children's Hospital Westmead Sydney New South Wales Australia
| | - Esmeralda Bordador
- Department of Metabolic Medicine Royal Children's Hospital Melbourne Victoria Australia
| | - Yiran Guo
- Center for Applied Genomics Children's Hospital of Philadelphia Philadelphia Pennsylvania USA
- Center for Data‐Driven Discovery in Biomedicine Children's Hospital of Philadelphia Philadelphia Pennsylvania USA
| | - Hakon Hakonarson
- Center for Applied Genomics Children's Hospital of Philadelphia Philadelphia Pennsylvania USA
- Department of Pediatrics, Perelman School of Medicine University of Pennsylvania Philadelphia Pennsylvania USA
| | - Alison G. Compton
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
- Brain and Mitochondrial Research Group Murdoch Children's Research Institute, Royal Children's Hospital Melbourne Victoria Australia
| | - David R. Thorburn
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
- Brain and Mitochondrial Research Group Murdoch Children's Research Institute, Royal Children's Hospital Melbourne Victoria Australia
| | - Sumudu Amarasekera
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
- Brain and Mitochondrial Research Group Murdoch Children's Research Institute, Royal Children's Hospital Melbourne Victoria Australia
| | - Justine Marum
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
| | - Alisha Monaco
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
| | - Crystle Lee
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
| | - Belinda Chong
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
| | - Sebastian Lunke
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
- Department of Pathology University of Melbourne Melbourne Victoria Australia
| | - Zornitza Stark
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
| | - John Christodoulou
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute Royal Children's Hospital Melbourne Victoria Australia
- Department of Paediatrics University of Melbourne Melbourne Victoria Australia
- Brain and Mitochondrial Research Group Murdoch Children's Research Institute, Royal Children's Hospital Melbourne Victoria Australia
- Discipline of Child & Adolescent Health, Sydney Medical School University of Sydney Sydney New South Wales Australia
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5
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Fan W, Jin X, Xu M, Xi Y, Lu W, Yang X, Guan MX, Ge W. FARS2 deficiency in Drosophila reveals the developmental delay and seizure manifested by aberrant mitochondrial tRNA metabolism. Nucleic Acids Res 2021; 49:13108-13121. [PMID: 34878141 PMCID: PMC8682739 DOI: 10.1093/nar/gkab1187] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 11/08/2021] [Accepted: 11/17/2021] [Indexed: 01/16/2023] Open
Abstract
Mutations in genes encoding mitochondrial aminoacyl-tRNA synthetases are linked to diverse diseases. However, the precise mechanisms by which these mutations affect mitochondrial function and disease development are not fully understood. Here, we develop a Drosophila model to study the function of dFARS2, the Drosophila homologue of the mitochondrial phenylalanyl–tRNA synthetase, and further characterize human disease-associated FARS2 variants. Inactivation of dFARS2 in Drosophila leads to developmental delay and seizure. Biochemical studies reveal that dFARS2 is required for mitochondrial tRNA aminoacylation, mitochondrial protein stability, and assembly and enzyme activities of OXPHOS complexes. Interestingly, by modeling FARS2 mutations associated with human disease in Drosophila, we provide evidence that expression of two human FARS2 variants, p.G309S and p.D142Y, induces seizure behaviors and locomotion defects, respectively. Together, our results not only show the relationship between dysfunction of mitochondrial aminoacylation system and pathologies, but also illustrate the application of Drosophila model for functional analysis of human disease-causing variants.
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Affiliation(s)
- Wenlu Fan
- Division of Human Reproduction and Developmental Genetics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.,Zhejiang Provincial Key Laboratory of Precision Diagnosis and Therapy for Major Gynecological Diseases, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, China
| | - Xiaoye Jin
- Division of Human Reproduction and Developmental Genetics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.,Zhejiang Provincial Key Laboratory of Precision Diagnosis and Therapy for Major Gynecological Diseases, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, China
| | - Man Xu
- Division of Human Reproduction and Developmental Genetics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.,Zhejiang Provincial Key Laboratory of Precision Diagnosis and Therapy for Major Gynecological Diseases, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, China
| | - Yongmei Xi
- Division of Human Reproduction and Developmental Genetics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China
| | - Weiguo Lu
- Department of Gynecologic Oncology, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, China.,Cancer Center, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiaohang Yang
- Division of Human Reproduction and Developmental Genetics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.,Zhejiang Provincial Key Laboratory of Genetic and Developmental Disorders, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Min-Xin Guan
- Institute of Genetics, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.,Zhejiang Provincial Key Laboratory of Genetic and Developmental Disorders, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Wanzhong Ge
- Division of Human Reproduction and Developmental Genetics, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, China.,Zhejiang Provincial Key Laboratory of Precision Diagnosis and Therapy for Major Gynecological Diseases, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310006, China.,Cancer Center, Zhejiang University, Hangzhou, Zhejiang 310058, China
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6
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Zuccolotto-Dos-Reis FH, Escarso SHA, Araujo JS, Espreafico EM, Alberici LC, Sobreira CFDR. Acetyl-CoA-driven respiration in frozen muscle contributes to the diagnosis of mitochondrial disease. Eur J Clin Invest 2021; 51:e13574. [PMID: 33937992 DOI: 10.1111/eci.13574] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/09/2021] [Accepted: 04/11/2021] [Indexed: 01/22/2023]
Abstract
BACKGROUND Freezing human biopsies is common in clinical practice for storage. However, this technique disrupts mitochondrial membranes, hampering further analyses of respiratory function. To contribute to laboratorial diagnosis of mitochondrial diseases, this study sought to develop a respirometry approach using O2k (Oroboros Ins.) to measure the whole electron transport chain (ETC) activity in homogenates of frozen skeletal muscle biopsies. PATIENTS AND METHODS We enrolled 16 patients submitted to muscle biopsy in the process of routine diagnostic investigation: four with mitochondrial disease and severe mitochondrial dysfunction; seven with exercise intolerance and multiple deletions of mitochondrial DNA, presenting mild to moderate mitochondrial dysfunction; five without mitochondrial disease, as controls. Whole homogenates of muscle fragments were prepared using grinder-type equipment. O2 consumption rates were normalized using citrate synthase activity. RESULTS Transmission electron microscopy confirmed mitochondrial membrane discontinuation, indicating increased permeability of mitochondrial membranes in homogenates from frozen biopsies. O2 consumption rates in the presence of acetyl-CoA lead to maximum respiratory rates sensitive to rotenone, malonate and antimycin. This protocol of acetyl-CoA-driven respiration (ACoAR), applied in whole homogenates of frozen muscle, was sensitive enough to identify ETC abnormality, even in patients with mild to moderate mitochondrial dysfunction. We demonstrated adequate repeatability of ACoAR and found significant correlation between O2 consumption rates and enzyme activity assays of individual ETC complexes. CONCLUSIONS We present preliminary data on a simple, low cost and reliable procedure to measure respiratory function in whole homogenates of frozen skeletal muscle biopsies, contributing to diagnosis of mitochondrial diseases in humans.
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Affiliation(s)
| | - Silvia Helena Andrião Escarso
- Department of Neurosciences, Division of Neurology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Jackeline Souza Araujo
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Enilza Maria Espreafico
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, São Paulo, Brazil
| | - Luciane Carla Alberici
- Department of BioMolecular Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
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7
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Wiessner M, Maroofian R, Ni MY, Pedroni A, Müller JS, Stucka R, Beetz C, Efthymiou S, Santorelli FM, Alfares AA, Zhu C, Uhrova Meszarosova A, Alehabib E, Bakhtiari S, Janecke AR, Otero MG, Chen JYH, Peterson JT, Strom TM, De Jonghe P, Deconinck T, De Ridder W, De Winter J, Pasquariello R, Ricca I, Alfadhel M, van de Warrenburg BP, Portier R, Bergmann C, Ghasemi Firouzabadi S, Jin SC, Bilguvar K, Hamed S, Abdelhameed M, Haridy NA, Maqbool S, Rahman F, Anwar N, Carmichael J, Pagnamenta A, Wood NW, Tran Mau-Them F, Haack T, Di Rocco M, Ceccherini I, Iacomino M, Zara F, Salpietro V, Scala M, Rusmini M, Xu Y, Wang Y, Suzuki Y, Koh K, Nan H, Ishiura H, Tsuji S, Lambert L, Schmitt E, Lacaze E, Küpper H, Dredge D, Skraban C, Goldstein A, Willis MJH, Grand K, Graham JM, Lewis RA, Millan F, Duman Ö, Dündar N, Uyanik G, Schöls L, Nürnberg P, Nürnberg G, Catala Bordes A, Seeman P, Kuchar M, Darvish H, Rebelo A, Bouçanova F, Medard JJ, Chrast R, Auer-Grumbach M, Alkuraya FS, Shamseldin H, Al Tala S, Rezazadeh Varaghchi J, Najafi M, Deschner S, Gläser D, Hüttel W, Kruer MC, Kamsteeg EJ, Takiyama Y, Züchner S, Baets J, Synofzik M, Schüle R, Horvath R, Houlden H, Bartesaghi L, Lee HJ, Ampatzis K, Pierson TM, Senderek J. Biallelic variants in HPDL cause pure and complicated hereditary spastic paraplegia. Brain 2021; 144:1422-1434. [PMID: 33970200 PMCID: PMC8219359 DOI: 10.1093/brain/awab041] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/04/2020] [Accepted: 12/02/2020] [Indexed: 01/19/2023] Open
Abstract
Human 4-hydroxyphenylpyruvate dioxygenase-like (HPDL) is a putative iron-containing non-heme oxygenase of unknown specificity and biological significance. We report 25 families containing 34 individuals with neurological disease associated with biallelic HPDL variants. Phenotypes ranged from juvenile-onset pure hereditary spastic paraplegia to infantile-onset spasticity and global developmental delays, sometimes complicated by episodes of neurological and respiratory decompensation. Variants included bona fide pathogenic truncating changes, although most were missense substitutions. Functionality of variants could not be determined directly as the enzymatic specificity of HPDL is unknown; however, when HPDL missense substitutions were introduced into 4-hydroxyphenylpyruvate dioxygenase (HPPD, an HPDL orthologue), they impaired the ability of HPPD to convert 4-hydroxyphenylpyruvate into homogentisate. Moreover, three additional sets of experiments provided evidence for a role of HPDL in the nervous system and further supported its link to neurological disease: (i) HPDL was expressed in the nervous system and expression increased during neural differentiation; (ii) knockdown of zebrafish hpdl led to abnormal motor behaviour, replicating aspects of the human disease; and (iii) HPDL localized to mitochondria, consistent with mitochondrial disease that is often associated with neurological manifestations. Our findings suggest that biallelic HPDL variants cause a syndrome varying from juvenile-onset pure hereditary spastic paraplegia to infantile-onset spastic tetraplegia associated with global developmental delays.
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Affiliation(s)
- Manuela Wiessner
- Friedrich-Baur-Institute, Department of Neurology, LMU Munich, Munich, Germany
| | - Reza Maroofian
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Meng-Yuan Ni
- Department of Biochemistry, National Defense Medical Center, Neihu, Taipei, Taiwan
| | - Andrea Pedroni
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Juliane S Müller
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Rolf Stucka
- Friedrich-Baur-Institute, Department of Neurology, LMU Munich, Munich, Germany
| | - Christian Beetz
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | | | - Ahmed A Alfares
- Department of Pediatrics, College of Medicine, Qassim University, Qassim, Saudi Arabia
| | - Changlian Zhu
- Henan Key Laboratory of Child Brain Injury, Institute of Neuroscience and Third Affliated Hospital of Zhengzhou University, Zhengzhou, China
- Center for Brain Repair and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg, Göteborg, Sweden
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Anna Uhrova Meszarosova
- DNA Laboratory, Department of Paediatric Neurology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Elham Alehabib
- Student Research Committee, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Somayeh Bakhtiari
- Barrow Neurological Institute, Phoenix Children's Hospital and University of Arizona College of Medicine, Phoenix, USA
| | - Andreas R Janecke
- Department of Pediatrics I, Medical University of Innsbruck, Innsbruck, Austria
- Division of Human Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Maria Gabriela Otero
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, USA
| | | | - James T Peterson
- Mitochondrial Medicine Frontier Program, Children's Hospital of Philadelphia, Philadelphia, USA
| | - Tim M Strom
- Institute of Human Genetics, Technische Universität Mänchen, Munich, Germany
| | - Peter De Jonghe
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerpen, Belgium
- Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium
- Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerpen, Belgium
| | - Tine Deconinck
- Center of Medical Genetics, University of Antwerp and Antwerp University Hospital, Antwerpen, Belgium
| | - Willem De Ridder
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerpen, Belgium
- Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium
- Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerpen, Belgium
| | - Jonathan De Winter
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerpen, Belgium
- Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium
- Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerpen, Belgium
| | | | - Ivana Ricca
- Molecular Medicine Unit, IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Majid Alfadhel
- Genetics Division, Department of Pediatrics, King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard Health Affairs (MNG-HA), Riyadh, Saudi Arabia
| | - Bart P van de Warrenburg
- Department of Neurology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Ruben Portier
- Polikliniek Neurologie Enschede, Medisch Spectrum Twente, Enschede, The Netherlands
| | - Carsten Bergmann
- Medizinische Genetik Mainz, Limbach Genetics, Mainz, Germany
- Department of Medicine, Nephrology, University Hospital Freiburg, Germany
| | | | - Sheng Chih Jin
- Department of Genetics, Washington University School of Medicine, St. Louis, USA
| | - Kaya Bilguvar
- Department of Genetics, Yale University School of Medicine, New Haven, USA
- Yale Center for Genome Analysis, Yale University, New Haven, USA
| | - Sherifa Hamed
- Department of Neurology and Psychiatry, Assiut University Hospital, Assiut, Egypt
| | - Mohammed Abdelhameed
- Department of Neurology and Psychiatry, Assiut University Hospital, Assiut, Egypt
| | - Nourelhoda A Haridy
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
- Department of Neurology and Psychiatry, Assiut University Hospital, Assiut, Egypt
| | - Shazia Maqbool
- Development and Behavioural Paediatrics Department, Institute of Child Health and The Children Hospital, Lahore, Pakistan
| | - Fatima Rahman
- Development and Behavioural Paediatrics Department, Institute of Child Health and The Children Hospital, Lahore, Pakistan
| | - Najwa Anwar
- Development and Behavioural Paediatrics Department, Institute of Child Health and The Children Hospital, Lahore, Pakistan
| | - Jenny Carmichael
- Oxford Regional Clinical Genetics Service, Northampton General Hospital, Northampton, UK
| | - Alistair Pagnamenta
- NIHR Oxford BRC, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Nick W Wood
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
- The National Hospital for Neurology and Neurosurgery, London, UK
| | - Frederic Tran Mau-Them
- Unité Fonctionnelle 6254 d'Innovation en Diagnostique Génomique des Maladies Rares, Pôle de Biologie, CHU Dijon Bourgogne, Dijon, France
| | - Tobias Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany
| | | | - Maja Di Rocco
- Rare Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Isabella Ceccherini
- Genetics and Genomics of Rare Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Michele Iacomino
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Federico Zara
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Genoa, Italy
| | - Vincenzo Salpietro
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Genoa, Italy
- Pediatric Neurology and Neuromuscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, Genoa, Italy
- Pediatric Neurology and Neuromuscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Marta Rusmini
- Genetics and Genomics of Rare Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Yiran Xu
- Henan Key Laboratory of Child Brain Injury, Institute of Neuroscience and Third Affliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yinghong Wang
- Department of Pediatrics, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Yasuhiro Suzuki
- Department of Pediatric Neurology, Osaka Women's and Children's Hospital, Osaka, Japan
| | - Kishin Koh
- Department of Neurology, Graduate School of Medical Sciences, University of Yamanashi, Yamanashi, Japan
| | - Haitian Nan
- Department of Neurology, Graduate School of Medical Sciences, University of Yamanashi, Yamanashi, Japan
| | - Hiroyuki Ishiura
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Shoji Tsuji
- Institute of Medical Genomics, International University of Health and Welfare, Chiba, Japan
| | - Laëtitia Lambert
- Department of Clinical Genetics, CHRU Nancy, UMR_S INSERM N-GERE 1256, Université de Lorraine - Faculté de Médecine, Nancy, France
| | | | - Elodie Lacaze
- Department of Medical Genetics, Le Havre Hospital, Le Havre, France
| | - Hanna Küpper
- Department of Pediatric Neurology, University Children's Hospital Tübingen, Tübingen, Germany
| | - David Dredge
- Neurology Department, Massachusetts General Hospital, Boston, USA
| | - Cara Skraban
- Roberts Individualized Medical Genetics Center, Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, USA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Amy Goldstein
- Mitochondrial Medicine Frontier Program, Children's Hospital of Philadelphia, Philadelphia, USA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Mary J H Willis
- Department of Pediatrics, Naval Medical Center San Diego, San Diego, USA
| | - Katheryn Grand
- Department of Pediatrics, Medical Genetics, Cedars-Sinai Medical Center, Los Angeles, USA
| | - John M Graham
- Department of Pediatrics, Medical Genetics, Cedars-Sinai Medical Center, Los Angeles, USA
| | - Richard A Lewis
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, USA
| | | | - Özgür Duman
- Department of Pediatric Neurology, Akdeniz University Hospital, Antalya, Turkey
| | - Nihal Dündar
- Department of Pediatric Neurology, Izmir Katip Celebi University, Izmir, Turkey
| | - Gökhan Uyanik
- Center for Medical Genetics, Hanusch Hospital, Vienna, Austria
- Medical School, Sigmund Freud Private University, Vienna, Austria
| | - Ludger Schöls
- Hertie Institute for Clinical Brain Research (HIH), Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
| | - Peter Nürnberg
- Cologne Center for Genomics, Faculty of Medicine and Cologne University Hospital, University of Cologne, Cologne, Germany
| | - Gudrun Nürnberg
- Cologne Center for Genomics, Faculty of Medicine and Cologne University Hospital, University of Cologne, Cologne, Germany
| | - Andrea Catala Bordes
- DNA Laboratory, Department of Paediatric Neurology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Pavel Seeman
- DNA Laboratory, Department of Paediatric Neurology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, Czech Republic
| | - Martin Kuchar
- Department of Paediatric Neurology, Liberec Hospital, Liberec, Czech Republic
| | - Hossein Darvish
- Neuroscience Research Center, Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran
| | - Adriana Rebelo
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA
| | - Filipa Bouçanova
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Jean-Jacques Medard
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Roman Chrast
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Michaela Auer-Grumbach
- Department of Orthopaedics and Traumatology, Medical University of Vienna, Vienna, Austria
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Hanan Shamseldin
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Saeed Al Tala
- Department of Pediatrics, Genetic Unit, Armed Forces Hospital, Khamis Mushayt, Saudi Arabia
| | | | - Maryam Najafi
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Dieter Gläser
- genetikum, Center for Human Genetics, Neu-Ulm, Germany
| | - Wolfgang Hüttel
- Institut für Pharmazeutische Wissenschaften, Albert-Ludwigs-Universität Freiburg, Freibug, Germany
| | - Michael C Kruer
- Barrow Neurological Institute, Phoenix Children's Hospital and University of Arizona College of Medicine, Phoenix, USA
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Yoshihisa Takiyama
- Department of Neurology, Graduate School of Medical Sciences, University of Yamanashi, Yamanashi, Japan
| | - Stephan Züchner
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, USA
| | - Jonathan Baets
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerpen, Belgium
- Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium
- Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Antwerpen, Belgium
| | - Matthis Synofzik
- Hertie Institute for Clinical Brain Research (HIH), Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
| | - Rebecca Schüle
- Hertie Institute for Clinical Brain Research (HIH), Center of Neurology, University of Tübingen, Tübingen, Germany
- German Center for Neurodegenerative Diseases (DZNE), University of Tübingen, Tübingen, Germany
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, Institute of Neurology, University College London, London, UK
| | - Luca Bartesaghi
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Hwei-Jen Lee
- Department of Biochemistry, National Defense Medical Center, Neihu, Taipei, Taiwan
| | | | - Tyler Mark Pierson
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, USA
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, USA
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, USA
- Center for the Undiagnosed Patient, Cedars-Sinai Medical Center, Los Angeles, USA
| | - Jan Senderek
- Friedrich-Baur-Institute, Department of Neurology, LMU Munich, Munich, Germany
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8
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Mizuguchi M, Ichiyama T, Imataka G, Okumura A, Goto T, Sakuma H, Takanashi JI, Murayama K, Yamagata T, Yamanouchi H, Fukuda T, Maegaki Y. Guidelines for the diagnosis and treatment of acute encephalopathy in childhood. Brain Dev 2021; 43:2-31. [PMID: 32829972 DOI: 10.1016/j.braindev.2020.08.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 08/04/2020] [Accepted: 08/04/2020] [Indexed: 12/16/2022]
Abstract
The cardinal symptom of acute encephalopathy is impairment of consciousness of acute onset during the course of an infectious disease, with duration and severity meeting defined criteria. Acute encephalopathy consists of multiple syndromes such as acute necrotizing encephalopathy, acute encephalopathy with biphasic seizures and late reduced diffusion and clinically mild encephalitis/encephalopathy with reversible splenial lesion. Among these syndromes, there are both similarities and differences. In 2016, the Japanese Society of Child Neurology published 'Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood', which made recommendations and comments on the general aspects of acute encephalopathy in the first half, and on individual syndromes in the latter half. Since the guidelines were written in Japanese, this review article describes extracts from the recommendations and comments in English, in order to introduce the essence of the guidelines to international clinicians and researchers.
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Affiliation(s)
- Masashi Mizuguchi
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
| | - Takashi Ichiyama
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Division of Pediatrics, Tsudumigaura Medical Center for Children with Disabilities, Yamaguchi, Japan
| | - George Imataka
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Pediatrics, Dokkyo Medical University, Tochigi, Japan
| | - Akihisa Okumura
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Pediatrics, Aichi Medical University, Aichi, Japan
| | - Tomohide Goto
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Division of Neurology, Kanagawa Children's Medical Center, Kanagawa, Japan
| | - Hiroshi Sakuma
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Brain and Neurosciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Jun-Ichi Takanashi
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Pediatrics, Tokyo Women's Medical University Yachiyo Medical Center, Yachiyo, Japan
| | - Kei Murayama
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Takanori Yamagata
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Pediatrics, Jichi Medical University, Tochigi, Japan
| | - Hideo Yamanouchi
- Committee for the Compilation of Guidelines for the Diagnosis and Treatment of Acute Encephalopathy in Childhood, Japanese Society of Child Neurology, Tokyo, Japan; Department of Pediatrics, Comprehensive Epilepsy Center, Saitama Medical University, Saitama, Japan
| | - Tokiko Fukuda
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu, Japan; Committee for the Integration of Guidelines, Japanese Society of Child Neurology, Tokyo, Japan
| | - Yoshihiro Maegaki
- Committee for the Integration of Guidelines, Japanese Society of Child Neurology, Tokyo, Japan; Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago, Japan
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9
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Xiao Y, Wang M, He Q, Xu L, Zhang Q, Meng F, Jia Z, Zhang F, Wang H, Guan MX. Asymmetrical effects of deafness-associated mitochondrial DNA 7516delA mutation on the processing of RNAs in the H-strand and L-strand polycistronic transcripts. Nucleic Acids Res 2020; 48:11113-11129. [PMID: 33045734 PMCID: PMC7641755 DOI: 10.1093/nar/gkaa860] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/10/2020] [Accepted: 09/23/2020] [Indexed: 12/31/2022] Open
Abstract
In this report, we investigated the molecular mechanism underlying a deafness-associated m.7516delA mutation affecting the 5′ end processing sites of mitochondrial tRNAAsp and tRNASer(UCN). An in vitro processing experiment demonstrated that m.7516delA mutation caused the aberrant 5′ end processing of tRNASer(UCN) and tRNAAsp precursors, catalyzed by RNase P. Using cytoplasmic hybrids (cybrids) derived from one hearing-impaired Chinese family bearing the m.7516delA mutation and control, we demonstrated the asymmetrical effects of m.7516delA mutation on the processing of tRNAs in the heavy (H)-strand and light (L)-strand polycistronic transcripts. Specially, the m.7516delA mutation caused the decreased levels of tRNASer(UCN) and downstream five tRNAs, including tRNATyr from the L-strand transcripts and tRNAAsp from the H-strand transcripts. Strikingly, mutant cybrids exhibited the lower level of COX2 mRNA and accumulation of longer and uncleaved precursors of COX2 from the H-strand transcripts. Aberrant RNA metabolisms yielded variable reductions in the mitochondrial proteins, especially marked reductions in the levels of ND4, ND5, CO1, CO2 and CO3. The impairment of mitochondrial translation caused the proteostasis stress and respiratory deficiency, diminished ATP production and membrane potential, increased production of reactive oxygen species and promoted apoptosis. Our findings provide new insights into the pathophysiology of deafness arising from mitochondrial tRNA processing defects.
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Affiliation(s)
- Yun Xiao
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, Shandong 250022, China
| | - Meng Wang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Qiufen He
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Lei Xu
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, Shandong 250022, China
| | - Qinghai Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Feilong Meng
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Zidong Jia
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China
| | - Fengguo Zhang
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, Shandong 250022, China
| | - Haibo Wang
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial ENT Hospital, Shandong University, Jinan, Shandong 250022, China
| | - Min-Xin Guan
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine and National Clinical Research Center for Child Health, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Key Lab of Reproductive Genetics, Ministry of Education of PRC, Zhejiang University, Hangzhou, Zhejiang 310058, China.,Joint Institute of Genetics and Genome Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang 310058, China
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10
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Takeda A, Murayama K, Okazaki Y, Imai-Okazaki A, Ohtake A, Takakuwa E, Yamazawa H, Izumi G, Abe J, Nagai A, Taniguchi K, Sasaki D, Tsujioka T, Basgen JM. Advanced pathological study for definite diagnosis of mitochondrial cardiomyopathy. J Clin Pathol 2020; 74:jclinpath-2020-206801. [PMID: 32817174 DOI: 10.1136/jclinpath-2020-206801] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 11/03/2022]
Abstract
AIMS Mitochondrial cardiomyopathy (MCM) is difficult to make a definite diagnosis because of various cardiovascular phenotypes and no diagnostic criteria in the pathology examination. We aim to add myocardial pathology to the diagnostic criteria for mitochondrial respiratory chain disorders. METHODS Quantitative analysis of mitochondria using electron microscopy and immunohistopathological analysis with respiratory chain enzyme antibodies were performed in 11 patients with hypertrophic or restrictive cardiomyopathy who underwent endomyocardial biopsy for possible MCM . Respiratory chain enzymatic assay in biopsied myocardium and genetic studies were also performed in all the subjects to define MCM. RESULTS Four patients were diagnosed with MCM according to the recent criteria of mitochondrial respiratory chain disorders. Using electron microscopy with quantitative analysis, the volume density of mitochondria within cardiac muscle cells was significantly increased in the MCM group compared with the non-MCM group (p=0.007). Immunohistopathological results were compatible with the result of the respiratory chain enzymatic assay. CONCLUSIONS Pathological diagnosis of MCM could be confirmed by a quantitative study of electron microscopy and immunohistopathological analysis using the mitochondrial respiratory chain enzyme subunit antibody.
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Affiliation(s)
- Atsuhito Takeda
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Juntendo University School of Medicine Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Atsuko Imai-Okazaki
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Juntendo University School of Medicine Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Akira Ohtake
- Department of Pediatrics & Clinical Genomics, Saitama Medical University Faculty of Medicine, Saitama, Japan
- Center for Intractable Diseases, Saitama Medical University, Saitama, Japan
| | - Emi Takakuwa
- Department of Surgical Pathology, Hokkaido University Hospital, Sapporo, Japan
| | - Hirokuni Yamazawa
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Gaku Izumi
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Jiro Abe
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Ayako Nagai
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Kota Taniguchi
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Daisuke Sasaki
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Takao Tsujioka
- Department of Pediatrics, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - John M Basgen
- Department of Research, Charles R Drew University of Medicine and Science, Los Angeles, California, USA
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11
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Ji Y, Zhang J, Lu Y, Yi Q, Chen M, Xie S, Mao X, Xiao Y, Meng F, Zhang M, Yang R, Guan MX. Complex I mutations synergize to worsen the phenotypic expression of Leber's hereditary optic neuropathy. J Biol Chem 2020; 295:13224-13238. [PMID: 32723871 DOI: 10.1074/jbc.ra120.014603] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/24/2020] [Indexed: 12/15/2022] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a maternal inheritance of eye disease because of the mitochondrial DNA (mtDNA) mutations. We previously discovered a 3866T>C mutation within the gene for the ND1 subunit of complex I as possibly amplifying disease progression for patients bearing the disease-causing 11778G>A mutation within the gene for the ND4 subunit of complex I. However, whether and how the ND1 mutation exacerbates the ND4 mutation were unknown. In this report, we showed that four Chinese families bearing both m.3866T>C and m.11778G>A mutations exhibited higher penetrances of LHON than 6 Chinese pedigrees carrying only the m.3866T>C mutation or families harboring only the m.11778G>A mutation. The protein structure analysis revealed that the m.3866T>C (I187T) and m.11778G>A (R340H) mutations destabilized the specific interactions with other residues of ND1 and ND4, thereby altering the structure and function of complex I. Cellular data obtained using cybrids, constructed by transferring mitochondria from the Chinese families into mtDNA-less (ρ°) cells, demonstrated that the mutations perturbed the stability, assembly, and activity of complex I, leading to changes in mitochondrial ATP levels and membrane potential and increasing the production of reactive oxygen species. These mitochondrial dysfunctions promoted the apoptotic sensitivity of cells and decreased mitophagy. Cybrids bearing only the m.3866T>C mutation displayed mild mitochondrial dysfunctions, whereas those harboring both m.3866T>C and m.11778G>A mutations exhibited greater mitochondrial dysfunctions. These suggested that the m.3866T>C mutation acted in synergy with the m.11778G>A mutation, aggravating mitochondrial dysfunctions and contributing to higher penetrance of LHON in these families carrying both mtDNA mutations.
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Affiliation(s)
- Yanchun Ji
- Department of Genetics and Metabolic Diseases, Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Division of Medical Genetics and Genomics, Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Juanjuan Zhang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yuanyuan Lu
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qiuzi Yi
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Mengquan Chen
- Department of Lab Medicine, Wenzhou Hospital of Traditional Chinese Medicine, Wenzhou, Zhejiang, China
| | - Shipeng Xie
- Department of Ophthalmology, Hebei Provincial Eye Hospital, Xingtai, Hebei, China
| | - Xiaoting Mao
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yun Xiao
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Feilong Meng
- Department of Genetics and Metabolic Diseases, Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Division of Medical Genetics and Genomics, Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Minglian Zhang
- Department of Ophthalmology, Hebei Provincial Eye Hospital, Xingtai, Hebei, China
| | - Rulai Yang
- Department of Genetics and Metabolic Diseases, Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
| | - Min-Xin Guan
- Division of Medical Genetics and Genomics, Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Key Lab of Reproductive Genetics, Ministry of Education of PRC, Zhejiang University, Hangzhou, Zhejiang, China; Joint Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang, China.
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12
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Ji Y, Zhang J, Yu J, Wang Y, Lu Y, Liang M, Li Q, Jin X, Wei Y, Meng F, Gao Y, Cang X, Tong Y, Liu X, Zhang M, Jiang P, Zhu T, Mo JQ, Huang T, Jiang P, Guan MX. Contribution of mitochondrial ND1 3394T>C mutation to the phenotypic manifestation of Leber's hereditary optic neuropathy. Hum Mol Genet 2020; 28:1515-1529. [PMID: 30597069 DOI: 10.1093/hmg/ddy450] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 11/05/2018] [Accepted: 12/22/2018] [Indexed: 11/14/2022] Open
Abstract
Mitochondrial DNA (mtDNA) mutations have been associated with Leber's hereditary optic neuropathy (LHON) and their pathophysiology remains poorly understood. In this study, we investigated the pathophysiology of a LHON susceptibility allele (m.3394T>C, p.30Y>H) in the Mitochondrial (MT)-ND1 gene. The incidence of m.3394T>C mutation was 2.7% in the cohort of 1741 probands with LHON. Extremely low penetrances of LHON were observed in 26 pedigrees carrying only m.3394T>C mutation, while 21 families bearing m.3394T>C, together with m.11778G>A or m.14484T>C mutation, exhibited higher penetrance of LHON than those in families carrying single mtDNA mutation(s). The m.3394T>C mutation disrupted the specific electrostatic interactions between Y30 of p.MT-ND1 with the sidechain of E4 and backbone carbonyl group of M1 of NDUFA1 (NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 1) of complex I, thereby altering the structure and function of complex I. We demonstrated that these cybrids bearing only m.3394T>C mutation caused mild mitochondrial dysfunctions and those harboring both m.3394T>C and m.11778G>A mutations exhibited greater mitochondrial dysfunctions than cybrids carrying only m.11778G>A mutation. In particular, the m.3394T>C mutation altered the stability of p.MT-ND1 and complex I assembly. Furthermore, the m.3394T>C mutation decreased the activities of mitochondrial complexes I, diminished mitochondrial ATP levels and membrane potential and increased the production of reactive oxygen species in the cybrids. These m.3394T>C mutation-induced alterations aggravated mitochondrial dysfunctions associated with the m.11778G>A mutation. These resultant biochemical defects contributed to higher penetrance of LHON in these families carrying both mtDNA mutations. Our findings provide new insights into the pathophysiology of LHON arising from the synergy between mitochondrial ND1 and ND4 mutations.
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Affiliation(s)
- Yanchun Ji
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Juanjuan Zhang
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jialing Yu
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Ying Wang
- Department of Ophthalmology, Chinese Academy of Traditional Chinese Medicine, Beijing, China
| | - Yuanyuan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Min Liang
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qiang Li
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xiaofen Jin
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yinsheng Wei
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Feilong Meng
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yinglong Gao
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xiaohui Cang
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yi Tong
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiaoling Liu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Minglian Zhang
- Department of Ophthalmology, Hebei Provincial Eye Hospital, Xingtai, Hebei, China
| | - Peifang Jiang
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Tao Zhu
- Department of Critical Care Medicine, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jun Qin Mo
- Department of Pathology, Rady Children's Hospital, University of California School of Medicine, San Diego, California, USA
| | - Taosheng Huang
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Pingping Jiang
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Min-Xin Guan
- Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Key Lab of Reproductive Genetics, Ministry of Education of PRC, Zhejiang University, Hangzhou, China.,Joint Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang, China
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13
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Li H, Hu B, Luo Q, Hu S, Luo Y, Zhao B, Gan Y, Li Y, Shi M, Nie Q, Zhang D, Zhang X. Runting and Stunting Syndrome Is Associated With Mitochondrial Dysfunction in Sex-Linked Dwarf Chicken. Front Genet 2020; 10:1337. [PMID: 32010193 PMCID: PMC6978286 DOI: 10.3389/fgene.2019.01337] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 12/09/2019] [Indexed: 11/13/2022] Open
Abstract
Runting and stunting syndrome (RSS) in chicken are commonly known as “frozen chicken.” The disease is characterized by lower body weight and slow growth and the incidence rate is widely 5%–20% in sex-linked dwarf (SLD) chickens. However, the etiology of RSS in chickens has plagued researchers for several decades. In this study, histopathology studies demonstrated that the hepatocytes of the RSS chickens contain many mitochondria with damaged and outer and inner membrane along with vacuolar hydropic degeneration. No mtDNA mutation was detected, but our microarray data showed that RSS chickens exhibited abnormal expression of genes, many of which are involved in oxidative phosphorylation (OXPHOS) and fatty acid metabolism. In particular, nuclear gene IGF2BP3 was upregulated in RSS chickens' liver cells. The abnormal expression of these genes is likely to impair the OXPHOS, resulting in reduced ATP synthesis in the hepatocytes of the RSS chickens, which may in turn leads to poor weight gain and retarded growth or stunting of chicks. Our findings suggest that mitochondria dysfunction rather than chronic inflammation is responsible for the reduced growth and RSS in SLD chickens. Mutations in GHR have been shown to compromise mitochondrial function in SLD chickens. Since the mitochondrial damage in the RSS chicken is more severe, we suggest that extra genes are likely to be affected to exacerbate the phenotype.
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Affiliation(s)
- Hongmei Li
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Bowen Hu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Qingbin Luo
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Shuang Hu
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yabiao Luo
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Bojing Zhao
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Yanmin Gan
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Ying Li
- Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Meiqing Shi
- Division of Immunology, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, College Park, MD, United States
| | - Qinghua Nie
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Dexiang Zhang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Xiquan Zhang
- Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.,Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Science, South China Agricultural University, Guangzhou, China
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14
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Gong S, Wang X, Meng F, Cui L, Yi Q, Zhao Q, Cang X, Cai Z, Mo JQ, Liang Y, Guan MX. Overexpression of mitochondrial histidyl-tRNA synthetase restores mitochondrial dysfunction caused by a deafness-associated tRNAHis mutation. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49906-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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15
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Frazier AE, Vincent AE, Turnbull DM, Thorburn DR, Taylor RW. Assessment of mitochondrial respiratory chain enzymes in cells and tissues. Methods Cell Biol 2019; 155:121-156. [PMID: 32183956 DOI: 10.1016/bs.mcb.2019.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Measurement of the individual enzymes involved in mitochondrial oxidative phosphorylation (OXPHOS) forms a key part of diagnostic investigations in patients with suspected mitochondrial disease, and can provide crucial information on mitochondrial OXPHOS function in a variety of cells and tissues that are applicable to many research investigations. In this chapter, we present methods for analysis of mitochondrial respiratory chain enzymes in cells and tissues based on assays performed in two geographically separate diagnostic referral centers, as part of clinical diagnostic investigations. Techniques for sample preparation from cells and tissues, and spectrophotometric assays for measurement of the activities of OXPHOS complexes I-V, the combined activity of complexes II+III, and the mitochondrial matrix enzyme citrate synthase, are provided. The activities of mitochondrial respiratory chain enzymes are often expressed relative to citrate synthase activity, since these ratios may be more robust in accounting for variability that may arise due to tissue quality, handling and storage, cell growth conditions, or any mitochondrial proliferation that may be present in tissues from patients with mitochondrial disease. Considerations for adaption of these techniques to other cells, tissues, and organisms are presented, as well as comparisons to alternate methods for analysis of respiratory chain function. In this context, a quantitative immunofluorescence protocol is also provided that is suitable for measurement of the amount of multiple respiratory chain complexes in small diagnostic tissue samples. The analysis and interpretation of OXPHOS enzyme activities are then placed in the context of mitochondrial disease tissue pathology and diagnosis.
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Affiliation(s)
- Ann E Frazier
- Brain and Mitochondrial Research, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Amy E Vincent
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Doug M Turnbull
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David R Thorburn
- Brain and Mitochondrial Research, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia; Victorian Clinical Genetics Services, Melbourne, VIC, Australia
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Mitochondrial Diagnostic Laboratory, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.
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16
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Gong S, Wang X, Meng F, Cui L, Yi Q, Zhao Q, Cang X, Cai Z, Mo JQ, Liang Y, Guan MX. Overexpression of mitochondrial histidyl-tRNA synthetase restores mitochondrial dysfunction caused by a deafness-associated tRNA His mutation. J Biol Chem 2019; 295:940-954. [PMID: 31819004 DOI: 10.1074/jbc.ra119.010998] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/27/2019] [Indexed: 01/19/2023] Open
Abstract
The deafness-associated m.12201T>C mutation affects the A5-U68 base-pairing within the acceptor stem of mitochondrial tRNAHis The primary defect in this mutation is an alteration in tRNAHis aminoacylation. Here, we further investigate the molecular mechanism of the deafness-associated tRNAHis 12201T>C mutation and test whether the overexpression of the human mitochondrial histidyl-tRNA synthetase gene (HARS2) in cytoplasmic hybrid (cybrid) cells carrying the m.12201T>C mutation reverses mitochondrial dysfunctions. Using molecular dynamics simulations, we demonstrate that the m.12201T>C mutation perturbs the tRNAHis structure and function, supported by decreased melting temperature, conformational changes, and instability of mutated tRNA. We show that the m.12201T>C mutation-induced alteration of aminoacylation tRNAHis causes mitochondrial translational defects and respiratory deficiency. We found that the transfer of HARS2 into the cybrids carrying the m.12201T>C mutation raises the levels of aminoacylated tRNAHis from 56.3 to 75.0% but does not change the aminoacylation of other tRNAs. Strikingly, HARS2 overexpression increased the steady-state levels of tRNAHis and of noncognate tRNAs, including tRNAAla, tRNAGln, tRNAGlu, tRNALeu(UUR), tRNALys, and tRNAMet, in cells bearing the m.12201T>C mutation. This improved tRNA metabolism elevated the efficiency of mitochondrial translation, activities of oxidative phosphorylation complexes, and respiration capacity. Furthermore, HARS2 overexpression markedly increased mitochondrial ATP levels and membrane potential and reduced production of reactive oxygen species in cells carrying the m.12201T>C mutation. These results indicate that HARS2 overexpression corrects the mitochondrial dysfunction caused by the tRNAHis mutation. These findings provide critical insights into the pathophysiology of mitochondrial disease and represent a step toward improved therapeutic interventions for mitochondrial disorders.
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Affiliation(s)
- Shasha Gong
- Taizhou University Hospital, Taizhou University, Taizhou, Zhejiang 318000, China.,Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiaoqiong Wang
- Department of Otolaryngology, Taizhou Municipal Hospital, Taizhou, Zhejiang 318000, China.,Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Feilong Meng
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China.,Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Limei Cui
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Qiuzi Yi
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Qiong Zhao
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xiaohui Cang
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Zhiyi Cai
- Department of Otolaryngology, Taizhou Municipal Hospital, Taizhou, Zhejiang 318000, China
| | - Jun Qin Mo
- Department of Pathology, Rady Children's Hospital, University of California School of Medicine, San Diego, California 92123
| | - Yong Liang
- Taizhou University Hospital, Taizhou University, Taizhou, Zhejiang 318000, China
| | - Min-Xin Guan
- Institute of Genetics, Zhejiang University, Hangzhou, Zhejiang 310058, China .,Division of Medical Genetics and Genomics, the Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Key Laboratory of Reproductive Genetics, Ministry of Education of PRC, Zhejiang University, Hangzhou, Zhejiang 310058, China.,Joint Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang 310058, China
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17
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Fan W, Zheng J, Kong W, Cui L, Aishanjiang M, Yi Q, Wang M, Cang X, Tang X, Chen Y, Mo JQ, Sondheimer N, Ge W, Guan MX. Contribution of a mitochondrial tyrosyl-tRNA synthetase mutation to the phenotypic expression of the deafness-associated tRNA Ser(UCN) 7511A>G mutation. J Biol Chem 2019; 294:19292-19305. [PMID: 31685661 DOI: 10.1074/jbc.ra119.010598] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 10/29/2019] [Indexed: 01/01/2023] Open
Abstract
Nuclear modifier genes have been proposed to modify the phenotypic expression of mitochondrial DNA mutations. Using a targeted exome-sequencing approach, here we found that the p.191Gly>Val mutation in mitochondrial tyrosyl-tRNA synthetase 2 (YARS2) interacts with the tRNASer(UCN) 7511A>G mutation in causing deafness. Strikingly, members of a Chinese family bearing both the YARS2 p.191Gly>Val and m.7511A>G mutations displayed much higher penetrance of deafness than those pedigrees carrying only the m.7511A>G mutation. The m.7511A>G mutation changed the A4:U69 base-pairing to G4:U69 pairing at the aminoacyl acceptor stem of tRNASer(UCN) and perturbed tRNASer(UCN) structure and function, including an increased melting temperature, altered conformation, instability, and aberrant aminoacylation of mutant tRNA. Using lymphoblastoid cell lines derived from symptomatic and asymptomatic members of these Chinese families and control subjects, we show that cell lines harboring only the m.7511A>G or p.191Gly>Val mutation revealed relatively mild defects in tRNASer(UCN) or tRNATyr metabolism, respectively. However, cell lines harboring both m.7511A>G and p.191Gly>Val mutations displayed more severe defective aminoacylations and lower tRNASer(UCN) and tRNATyr levels, aberrant aminoacylation, and lower levels of other tRNAs, including tRNAThr, tRNALys, tRNALeu(UUR), and tRNASer(AGY), than those in the cell lines carrying only the m.7511A>G or p.191Gly>Val mutation. Furthermore, mutant cell lines harboring both m.7511A>G and p.191Gly>Val mutations exhibited greater decreases in the levels of mitochondrial translation, respiration, and mitochondrial ATP and membrane potentials, along with increased production of reactive oxygen species. Our findings provide molecular-level insights into the pathophysiology of maternally transmitted deafness arising from the synergy between tRNASer(UCN) and mitochondrial YARS mutations.
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Affiliation(s)
- Wenlu Fan
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Attardi Institute of Biomedicine, School of Life Sciences and Laboratory Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China
| | - Jing Zheng
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Wanzhong Kong
- Attardi Institute of Biomedicine, School of Life Sciences and Laboratory Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China
| | - Limei Cui
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Maerhaba Aishanjiang
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Qiuzi Yi
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Min Wang
- Attardi Institute of Biomedicine, School of Life Sciences and Laboratory Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China
| | - Xiaohui Cang
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Xiaowen Tang
- Attardi Institute of Biomedicine, School of Life Sciences and Laboratory Medicine, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China
| | - Ye Chen
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Jun Qin Mo
- Department of Pathology, Rady Children's Hospital, University of California School of Medicine, San Diego, California 92123
| | - Neal Sondheimer
- Department of Molecular Genetics, University of Toronto School of Medicine and the Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Wanzhong Ge
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Min-Xin Guan
- Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China .,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Key Laboratory of Reproductive Genetics, Ministry of Education of PRC, Zhejiang University, Hangzhou, Zhejiang 310058, China.,Joint Institute of Genetics and Genome Medicine between Zhejiang University and the University of Toronto, Hangzhou, Zhejiang 310058, China
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18
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Alfadhel M, Nashabat M, Abu Ali Q, Hundallah K. Mitochondrial iron-sulfur cluster biogenesis from molecular understanding to clinical disease. ACTA ACUST UNITED AC 2019; 22:4-13. [PMID: 28064324 PMCID: PMC5726836 DOI: 10.17712/nsj.2017.1.20160542] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Iron–sulfur clusters (ISCs) are known to play a major role in various protein functions. Located in the mitochondria, cytosol, endoplasmic reticulum and nucleus, they contribute to various core cellular functions. Until recently, only a few human diseases related to mitochondrial ISC biogenesis defects have been described. Such diseases include Friedreich ataxia, combined oxidative phosphorylation deficiency 19, infantile complex II/III deficiency defect, hereditary myopathy with lactic acidosis and mitochondrial muscle myopathy, lipoic acid biosynthesis defects, multiple mitochondrial dysfunctions syndromes and non ketotic hyperglycinemia due to glutaredoxin 5 gene defect. Disorders of mitochondrial import, export and translation, including sideroblastic anemia with ataxia, EVEN-PLUS syndrome and mitochondrial complex I deficiency due to nucleotide-binding protein-like protein gene defect, have also been implicated in ISC biogenesis defects. With advances in next generation sequencing technologies, more disorders related to ISC biogenesis defects are expected to be elucidated. In this article, we aim to shed the light on mitochondrial ISC biogenesis, related proteins and their function, pathophysiology, clinical phenotypes of related disorders, diagnostic approach, and future implications.
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Affiliation(s)
- Majid Alfadhel
- Division of Genetics, Department of Pediatrics, King Saud bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia
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19
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Growth Hormone Receptor Gene is Essential for Chicken Mitochondrial Function In Vivo and In Vitro. Int J Mol Sci 2019; 20:ijms20071608. [PMID: 30935132 PMCID: PMC6480491 DOI: 10.3390/ijms20071608] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 03/27/2019] [Accepted: 03/28/2019] [Indexed: 12/12/2022] Open
Abstract
The growth hormone receptor (GHR) gene is correlated with many phenotypic and physiological alternations in chicken, such as shorter shanks, lower body weight and muscle mass loss. However, the role of the GHR gene in mitochondrial function remains unknown in poultry. In this study, we assessed the function of mitochondria in sex-linked dwarf (SLD) chicken skeletal muscle and interfered with the expression of GHR in DF-1 cells to investigate the role of the GHR gene in chicken mitochondrial function both in vivo and in vitro. We found that the expression of key regulators of mitochondrial biogenesis and mitochondrial DNA (mtDNA)-encoded oxidative phosphorylation (OXPHOS) genes were downregulated and accompanied by reduced enzymatic activity of OXPHOS complexes in SLD chicken skeletal muscle and GHR knockdown cells. Then, we assessed mitochondrial function by measuring mitochondrial membrane potential (ΔΨm), mitochondrial swelling, reactive oxygen species (ROS) production, malondialdehyde (MDA) levels, ATP levels and the mitochondrial respiratory control ratio (RCR), and found that mitochondrial function was impaired in SLD chicken skeletal muscle and GHR knockdown cells. In addition, we also studied the morphology and structure of mitochondria in GHR knockdown cells by transmission electron microscopy (TEM) and MitoTracker staining. We found that knockdown of GHR could reduce mitochondrial number and alter mitochondrial structure in DF-1 cells. Above all, we demonstrated for the first time that the GHR gene is essential for chicken mitochondrial function in vivo and in vitro.
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20
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Zhang J, Ji Y, Lu Y, Fu R, Xu M, Liu X, Guan MX. Leber's hereditary optic neuropathy (LHON)-associated ND5 12338T > C mutation altered the assembly and function of complex I, apoptosis and mitophagy. Hum Mol Genet 2019; 27:1999-2011. [PMID: 29579248 DOI: 10.1093/hmg/ddy107] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/19/2018] [Indexed: 02/04/2023] Open
Abstract
Mutations in mitochondrial DNA (mtDNA) have been associated with Leber's hereditary optic neuropathy (LHON) and their pathophysiology remains poorly understood. In this study, we demonstrated that a missense mutation (m.12338T>C, p.1M>T) in the ND5 gene contributed to the pathogenesis of LHON. The m.12338T>C mutation affected the first methionine (Met1) with a threonine and shortened two amino acids of ND5. We therefore hypothesized that the mutated ND5 perturbed the structure and function of complex I. Using the cybrid cell models, generated by fusing mtDNA-less (ρ°) cells with enucleated cells from LHON patients carrying the m.12338T>C mutation and a control subject belonging to the same mtDNA haplogroup, we demonstrated that the m.12338T>C mutation caused the reduction of ND5 polypeptide, perturbed assemble and activity of complex I. Furthermore, the m.12338T>C mutation caused respiratory deficiency, diminished mitochondrial adenosine triphosphate levels and membrane potential and increased the production of reactive oxygen species. The m.12338T>C mutation promoted apoptosis, evidenced by elevated release of cytochrome c into cytosol and increased levels of apoptosis-activated proteins: caspases 9, 3, 7 and Poly ADP ribose polymerase in the cybrids carrying the m.12338T>C mutation, as compared with control cybrids. Moreover, we also document the involvement of m.12338T>C mutation in decreased mitophagy, as showed by reduced levels of autophagy protein light chain 3 and accumulation of autophagic substrate p62 in the in mutant cybrids as compared with control cybrids. These data demonstrated the direct link between mitochondrial dysfunction caused by complex I mutation and apoptosis or mitophagy. Our findings may provide new insights into the pathophysiology of LHON.
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Affiliation(s)
- Juanjuan Zhang
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China.,Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, China
| | - Yanchun Ji
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Yuanyuan Lu
- Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China.,Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, China
| | - Runing Fu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China.,Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, China
| | - Man Xu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China.,Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, China
| | - Xiaoling Liu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China.,Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, China
| | - Min-Xin Guan
- Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China.,Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang 325600, China.,Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, Wenzhou Medical College, Wenzhou, Zhejiang 325035, China.,Joint Institute of Genetics and Genome Medicine between Zhejiang University and University of Toronto, Hangzhou, Zhejiang, China
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21
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Otero MG, Tiongson E, Diaz F, Haude K, Panzer K, Collier A, Kim J, Adams D, Tifft CJ, Cui H, Millian Zamora F, Au MG, Graham JM, Buckley DJ, Lewis R, Toro C, Bai R, Turner L, Mathews KD, Gahl W, Pierson TM. Novel pathogenic COX20 variants causing dysarthria, ataxia, and sensory neuropathy. Ann Clin Transl Neurol 2018; 6:154-160. [PMID: 30656193 PMCID: PMC6331954 DOI: 10.1002/acn3.661] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 09/04/2018] [Accepted: 09/10/2018] [Indexed: 01/28/2023] Open
Abstract
COX20/FAM36A encodes a mitochondrial complex IV assembly factor important for COX2 activation. Only one homozygous COX20 missense mutation has been previously described in two separate consanguineous families. We report four subjects with features that include childhood hypotonia, areflexia, ataxia, dysarthria, dystonia, and sensory neuropathy. Exome sequencing in all four subjects identified the same novel COX20 variants. One variant affected the splice donor site of intron‐one (c.41A>G), while the other variant (c.157+3G>C) affected the splice donor site of intron‐two. cDNA and protein analysis indicated that no full‐length cDNA or protein was generated. These subjects expand the phenotype associated with COX20 deficiency.
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Affiliation(s)
- Maria G Otero
- Board of Governors Regenerative Medicine Institute Cedars-Sinai Medical Center Los Angeles California
| | - Emmanuelle Tiongson
- Division of Neurology Children's Hospital of Los Angeles Los Angeles California
| | - Frank Diaz
- Department of Neurology Cedars-Sinai Medical Center Los Angeles California
| | | | - Karin Panzer
- Department of Pediatrics University of Iowa Stead Family Children's Hospital Iowa City Iowa
| | - Ashley Collier
- Provincial Medical Genetics Program Eastern Health St. John's Newfoundland and Labrador Canada
| | - Jaemin Kim
- Board of Governors Regenerative Medicine Institute Cedars-Sinai Medical Center Los Angeles California
| | - David Adams
- NIH Undiagnosed Diseases Program NIH Office of Rare Diseases Research and NHGRI Bethesda Maryland.,Office of the Clinical Director NHGRI, NIH Bethesda Maryland
| | - Cynthia J Tifft
- NIH Undiagnosed Diseases Program NIH Office of Rare Diseases Research and NHGRI Bethesda Maryland.,Office of the Clinical Director NHGRI, NIH Bethesda Maryland
| | | | | | - Margaret G Au
- Department of Pediatrics Cedars-Sinai Medical Center Los Angeles California
| | - John M Graham
- Department of Pediatrics Cedars-Sinai Medical Center Los Angeles California
| | - David J Buckley
- Department of Pediatrics Janeway Health Centre St. John's Newfoundland and Labrador Canada
| | - Richard Lewis
- Department of Neurology Cedars-Sinai Medical Center Los Angeles California
| | - Camilo Toro
- NIH Undiagnosed Diseases Program NIH Office of Rare Diseases Research and NHGRI Bethesda Maryland.,Office of the Clinical Director NHGRI, NIH Bethesda Maryland
| | | | - Lesley Turner
- Faculty of Medicine Memorial University of Newfoundland St. John's Newfoundland Canada
| | - Katherine D Mathews
- Provincial Medical Genetics Program Eastern Health St. John's Newfoundland and Labrador Canada.,Department of Neurology University of Iowa Stead Family Children's Hospital Iowa City Iowa
| | - William Gahl
- NIH Undiagnosed Diseases Program NIH Office of Rare Diseases Research and NHGRI Bethesda Maryland.,Office of the Clinical Director NHGRI, NIH Bethesda Maryland
| | - Tyler Mark Pierson
- Board of Governors Regenerative Medicine Institute Cedars-Sinai Medical Center Los Angeles California.,Department of Neurology Cedars-Sinai Medical Center Los Angeles California.,Department of Pediatrics Cedars-Sinai Medical Center Los Angeles California
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22
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Xue L, Chen Y, Tang X, Yao J, Huang H, Wang M, Ye S, Wang M, Guan MX. A deafness-associated mitochondrial DNA mutation altered the tRNA Ser(UCN) metabolism and mitochondrial function. Mitochondrion 2018; 46:370-379. [PMID: 30336267 DOI: 10.1016/j.mito.2018.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/09/2018] [Accepted: 10/08/2018] [Indexed: 11/28/2022]
Abstract
Mutations in mitochondrial DNA (mtDNA) have been associated with deafness and their pathophysiology remains poorly understood. In this study, we investigated the pathogenic mechanism of deafness-associated 7505A > G variant in the mitochondrial tRNASer(UCN). The m.7505A > G variant affected the highly conserved adenine at position 11 (A11), disrupted the highly conserved A11-U24 base-pairing of DHU stem of tRNASer(UCN) and introduced a tertiary base pairing (G11-C56) with the C56 in the TΨC loop. We therefore hypothesized that the m.7505A > G variant altered both structure and function of tRNASer(UCN). We demonstrated that the m.7505A > G variant perturbed the conformation and stability of tRNASer(UCN), as indicated by an increased melting temperature and electrophoretic mobility of the mutated tRNA compared with the wild type molecule. Using the cybrids constructed by transferring mitochondria from the Chinese family into mitochondrial DNA (mtDNA)-less cells, we demonstrated the m.7505A > G variant led to significantly decreased steady-state levels of tRNASer(UCN) in the mutant cybrids, as compared with those of control cybrids. The aberrant tRNASer(UCN) metabolism resulted in the variable decreases in mtDNA-encoded polypeptides in the mutant cybrids. Furthermore, we demonstrated that the m.7505A > G variant decreased the activities of mitochondrial respiratory complexes I, III and IV, markedly diminished mitochondrial ATP levels and membrane potential, and increased the production of reactive oxygen species in the mutant cybrids. These results demonstrated that the m.7505A > G variant affected both structure and function of tRNASer(UCN) and consequently altered mitochondrial function. Our findings highlighted critical insights into the pathophysiology of maternally inherited deafness, which is manifested by the aberrant tRNA metabolism.
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Affiliation(s)
- Ling Xue
- Attardi Institute of Mitochondrial Biomedicine, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Zhejiang 325035, China
| | - Yaru Chen
- Attardi Institute of Mitochondrial Biomedicine, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Zhejiang 325035, China; Institute of Genetics, Zhejiang University School of Medicine, Zhejiang, Hangzhou 310058, China; Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Zhejiang, Hangzhou, China
| | - Xiaowen Tang
- Attardi Institute of Mitochondrial Biomedicine, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Zhejiang 325035, China
| | - Juan Yao
- Attardi Institute of Mitochondrial Biomedicine, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Zhejiang 325035, China
| | - Huimin Huang
- Attardi Institute of Mitochondrial Biomedicine, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Zhejiang 325035, China
| | - Min Wang
- Attardi Institute of Mitochondrial Biomedicine, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Zhejiang 325035, China
| | - Shixin Ye
- Laboratory of Computational and Quantitative Biology, Université Pierre-et-Marie-Curie, CNRS, Paris, France
| | - Meng Wang
- Institute of Genetics, Zhejiang University School of Medicine, Zhejiang, Hangzhou 310058, China; Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Zhejiang, Hangzhou, China
| | - Min-Xin Guan
- Attardi Institute of Mitochondrial Biomedicine, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Zhejiang 325035, China; Institute of Genetics, Zhejiang University School of Medicine, Zhejiang, Hangzhou 310058, China; Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Zhejiang, Hangzhou, China; Key Laboratory of Reproductive Genetics, Ministry of Education of PRC, Zhejiang University, Hangzhou, China; Joint Institute of Genetics and Genomic Medicine, University of Toronto, Zhejiang University, Hangzhou, Zhejiang, China.
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23
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Meng F, He Z, Tang X, Zheng J, Jin X, Zhu Y, Ren X, Zhou M, Wang M, Gong S, Mo JQ, Shu Q, Guan MX. Contribution of the tRNA Ile 4317A→G mutation to the phenotypic manifestation of the deafness-associated mitochondrial 12S rRNA 1555A→G mutation. J Biol Chem 2018; 293:3321-3334. [PMID: 29348176 DOI: 10.1074/jbc.ra117.000530] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/14/2018] [Indexed: 12/28/2022] Open
Abstract
The 1555A→G mutation in mitochondrial 12S rRNA has been associated with aminoglycoside-induced and non-syndromic deafness in many individuals worldwide. Mitochondrial genetic modifiers are proposed to influence the phenotypic expression of m.1555A→G mutation. Here, we report that a deafness-susceptibility allele (m.4317A→G) in the tRNAIle gene modulates the phenotype expression of m.1555A→G mutation. Strikingly, a large Han Chinese pedigree carrying both m.4317A→G and m.1555A→G mutations exhibited much higher penetrance of deafness than those carrying only the m.1555A→G mutation. The m.4317A→G mutation affected a highly conserved adenine at position 59 in the T-loop of tRNAIle We therefore hypothesized that the m.4317A→G mutation alters both structure and function of tRNAIle Using lymphoblastoid cell lines derived from members of Chinese families (three carrying both m.1555A→G and m.4317A→G mutations, three harboring only m.1555A→G mutation, and three controls lacking these mutations), we found that the cell lines bearing both m.4317A→G and m.1555A→G mutations exhibited more severe mitochondrial dysfunctions than those carrying only the m.1555A→G mutation. We also found that the m.4317A→G mutation perturbed the conformation, stability, and aminoacylation efficiency of tRNAIle These m.4317A→G mutation-induced alterations in tRNAIle structure and function aggravated the defective mitochondrial translation and respiratory phenotypes associated with the m.1555A→G mutation. Furthermore, mutant cell lines bearing both m.4317A→G and m.1555A→G mutations exhibited greater reductions in the mitochondrial ATP levels and membrane potentials and increasing production of reactive oxygen species than those carrying only the m.1555A→G mutation. Our findings provide new insights into the pathophysiology of maternally inherited deafness arising from the synergy between mitochondrial 12S rRNA and tRNA mutations.
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Affiliation(s)
- Feilong Meng
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China.,the Institute of Genetics
| | - Zheyun He
- the Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, and.,the Institute of Liver Diseases, Ningbo Secondary Hospital, Ningbo, Zhejiang 315010, China
| | - Xiaowen Tang
- the Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, and
| | - Jing Zheng
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China.,the Institute of Genetics
| | | | - Yi Zhu
- Department of Otolaryngology, The First Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Xiaoyan Ren
- the Attardi Institute of Mitochondrial Biomedicine, School of Life Sciences, and
| | - Mi Zhou
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China.,the Institute of Genetics
| | - Meng Wang
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China.,the Institute of Genetics
| | - Shasha Gong
- the Institute of Genetics.,the School of Medicine, Taizhou College, Taizhou, Zhejiang 318000, China, and
| | - Jun Qin Mo
- the Department of Pathology, Rady Children's Hospital, University of California at San Diego, San Diego, California 92123
| | - Qiang Shu
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China,
| | - Min-Xin Guan
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310052, China, .,the Institute of Genetics.,Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, and.,Joint Institute of Genetics and Genome Medicine between Zhejiang University and University of Toronto, Zhejiang University, Hangzhou, Zhejiang 310058, China
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24
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Zhou M, Xue L, Chen Y, Li H, He Q, Wang B, Meng F, Wang M, Guan MX. A hypertension-associated mitochondrial DNA mutation introduces an m 1G37 modification into tRNA Met, altering its structure and function. J Biol Chem 2017; 293:1425-1438. [PMID: 29222331 DOI: 10.1074/jbc.ra117.000317] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/13/2017] [Indexed: 12/20/2022] Open
Abstract
Defective nucleotide modifications of mitochondrial tRNAs have been associated with several human diseases, but their pathophysiology remains poorly understood. In this report, we investigated the pathogenic molecular mechanism underlying a hypertension-associated 4435A→G mutation in mitochondrial tRNAMet The m.4435A→G mutation affected a highly conserved adenosine at position 37, 3' adjacent to the tRNA's anticodon, which is important for the fidelity of codon recognition and stabilization. We hypothesized that the m.4435A→G mutation introduced an m1G37 modification of tRNAMet, altering its structure and function. Primer extension and methylation activity assays indeed confirmed that the m.4435A→G mutation created a tRNA methyltransferase 5 (TRMT5)-catalyzed m1G37 modification of tRNAMet We found that this mutation altered the tRNAMet structure, indicated by an increased melting temperature and electrophoretic mobility of the mutated tRNA compared with the wildtype molecule. We demonstrated that cybrid cell lines carrying the m.4435A→G mutation exhibited significantly decreased efficiency in aminoacylation and steady-state levels of tRNAMet, as compared with those of control cybrids. The aberrant tRNAMet metabolism resulted in variable decreases in mitochondrial DNA (mtDNA)-encoded polypeptides in the mutant cybrids. Furthermore, we found that the m.4435A→G mutation caused respiratory deficiency, markedly diminished mitochondrial ATP levels and membrane potential, and increased the production of reactive oxygen species in mutant cybrids. These results demonstrated that an aberrant m1G37 modification of mitochondrial tRNAMet affected the structure and function of its tRNA and consequently altered mitochondrial function. Our findings provide critical insights into the pathophysiology of maternally inherited hypertension, which is manifested by the deficient tRNA nucleotide modification.
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Affiliation(s)
- Mi Zhou
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Ling Xue
- the Attardi Institute of Mitochondrial Biomedicine and
| | - Yaru Chen
- the Attardi Institute of Mitochondrial Biomedicine and
| | - Haiying Li
- the Department of Cardiology, the First Affiliated Hospital, Wenzhou Medical University, Wenzhou, 325035 Zhejiang, China
| | - Qiufen He
- the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Bibin Wang
- the Attardi Institute of Mitochondrial Biomedicine and
| | - Feilong Meng
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Meng Wang
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China
| | - Min-Xin Guan
- From the Division of Medical Genetics and Genomics, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China, .,the Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, 310058 Zhejiang, China.,the Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, 310058 Zhejiang, China, and.,the Joining Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou, 310058 Zhejiang, China
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25
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Zhang J, Ji Y, Liu X, Chen J, Wang B, Zhang M, Guan MX. Leber's hereditary optic neuropathy caused by a mutation in mitochondrial tRNA Thr in eight Chinese pedigrees. Mitochondrion 2017; 42:84-91. [PMID: 29225014 DOI: 10.1016/j.mito.2017.12.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 11/09/2017] [Accepted: 12/06/2017] [Indexed: 01/09/2023]
Abstract
PURPOSE The purpose of this study was to investigate the pathophysiology underlying Leber's hereditary optic neuropathy (LHON)-associated mitochondrial tRNA mutation. METHODS Severn hundred ninety-seven Han Chinese subjects underwent clinical and genetic evaluation and analysis of mitochondrial DNA (mtDNA). The cybrid cell lines were constructed by transferring mitochondria from lymphoblastoid cell lines derived from a Chinese family into mtDNA-less (ρo) cells. These cell lines were assayed by tRNA Northern blot and Western blot analyses, respiratory enzymatic activities, the rate of ATP production and the generation of reactive oxygen species. RESULTS The tRNAThr 15927G>A mutation was identified in eight probands with suggestively maternal inheritance among 352 Han Chinese probands lacking these known LHON-associated mtDNA mutations. The m.15927G>A mutation affected a highly conserved guanine at position 42 at the anticodon-stem of tRNAThr, destabilizing the conservative base pairing (28C-42G). We therefore hypothesized that the m.15927G>A mutation, and altered the structure and function of tRNAThr. Northern blot analysis revealed 60% decrease in the steady-state level of tRNAThr in the mutant cell lines. Western blot analysis showed the variable reductions of 4 mtDNA encoding proteins, especially for marked decrease of ND1 and CYTB observed in mutant cell lines. Furthermore, we demonstrated that the m.15927G>A mutation decreased the activities of mitochondrial complexes I and III, markedly diminished mitochondrial ATP levels, and increased the production of reactive oxygen species in the mutant cells. CONCLUSIONS Our data demonstrated the first mitochondrial tRNA mutation leading to LHON. Our findings may provide new insights into the understanding of pathophysiology of LHON.
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Affiliation(s)
- Juanjuan Zhang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China; Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yanchun Ji
- Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xiaoling Liu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jie Chen
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Bibin Wang
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Minglian Zhang
- Department of Ophthalmology, Hebei Provincial Eye Hospital, Xingtai, Hebei, China
| | - Min-Xin Guan
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou, Zhejiang, China; Division of Medical Genetics and Genomics, Zhejiang Children's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Institute of Genetics, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Department of Ophthalmology, Hebei Provincial Eye Hospital, Xingtai, Hebei, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China.
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26
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Vantroys E, Larson A, Friederich M, Knight K, Swanson MA, Powell CA, Smet J, Vergult S, De Paepe B, Seneca S, Roeyers H, Menten B, Minczuk M, Vanlander A, Van Hove J, Van Coster R. New insights into the phenotype of FARS2 deficiency. Mol Genet Metab 2017; 122:172-181. [PMID: 29126765 PMCID: PMC5734183 DOI: 10.1016/j.ymgme.2017.10.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 12/12/2022]
Abstract
Mutations in FARS2 are known to cause dysfunction of mitochondrial translation due to deficient aminoacylation of the mitochondrial phenylalanine tRNA. Here, we report three novel mutations in FARS2 found in two patients in a compound heterozygous state. The missense mutation c.1082C>T (p.Pro361Leu) was detected in both patients. The mutations c.461C>T (p.Ala154Val) and c.521_523delTGG (p.Val174del) were each detected in one patient. We report abnormal in vitro aminoacylation assays as a functional validation of the molecular genetic findings. Based on the phenotypic data of previously reported subjects and the two subjects reported here, we conclude that FARS2 deficiency can be associated with two phenotypes: (i) an epileptic phenotype, and (ii) a spastic paraplegia phenotype.
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Affiliation(s)
- Elise Vantroys
- Department of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Austin Larson
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, CO, USA
| | - Marisa Friederich
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, CO, USA
| | - Kaz Knight
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, CO, USA
| | - Michael A Swanson
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, CO, USA
| | - Christopher A Powell
- MRC Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Joél Smet
- Department of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Sarah Vergult
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - Boel De Paepe
- Department of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Sara Seneca
- Center for Medical Genetics, UZ Brussel and Reproduction Genetics and Regenerative Medicine, Vrije Universiteit Brussel, Brussels, Belgium
| | - Herbert Roeyers
- Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium
| | - Björn Menten
- Center for Medical Genetics Ghent, Ghent University, Ghent, Belgium
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
| | - Arnaud Vanlander
- Department of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Johan Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, Aurora, CO, USA
| | - Rudy Van Coster
- Department of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium.
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27
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Ogawa E, Shimura M, Fushimi T, Tajika M, Ichimoto K, Matsunaga A, Tsuruoka T, Ishige M, Fuchigami T, Yamazaki T, Mori M, Kohda M, Kishita Y, Okazaki Y, Takahashi S, Ohtake A, Murayama K. Clinical validity of biochemical and molecular analysis in diagnosing Leigh syndrome: a study of 106 Japanese patients. J Inherit Metab Dis 2017; 40:685-693. [PMID: 28429146 PMCID: PMC5579154 DOI: 10.1007/s10545-017-0042-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 03/01/2017] [Accepted: 03/24/2017] [Indexed: 01/30/2023]
Abstract
Leigh syndrome (LS) is a progressive neurodegenerative disorder of infancy and early childhood. It is clinically diagnosed by typical manifestations and characteristic computed tomography (CT) or magnetic resonance imaging (MRI) studies. Unravelling mitochondrial respiratory chain (MRC) dysfunction behind LS is essential for deeper understanding of the disease, which may lead to the development of new therapies and cure. The aim of this study was to evaluate the clinical validity of various diagnostic tools in confirming MRC disorder in LS and Leigh-like syndrome (LL). The results of enzyme assays, molecular analysis, and cellular oxygen consumption rate (OCR) measurements were examined. Of 106 patients, 41 were biochemically and genetically verified, and 34 had reduced MRC activity but no causative mutations. Seven patients with normal MRC complex activities had mutations in the MT-ATP6 gene. Five further patients with normal activity in MRC were identified with causative mutations. Conversely, 12 out of 60 enzyme assays performed for genetically verified patients returned normal results. No biochemical or genetic background was confirmed for 19 patients. OCR was reduced in ten out of 19 patients with negative enzyme assay results. Inconsistent enzyme assay results between fibroblast and skeletal muscle biopsy samples were observed in 33% of 37 simultaneously analyzed cases. These data suggest that highest diagnostic rate is reached using a combined enzymatic and genetic approach, analyzing more than one type of biological materials where suitable. Microscale oxygraphy detected MRC impairment in 50% cases with no defect in MRC complex activities.
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Affiliation(s)
- Erika Ogawa
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Masaru Shimura
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Takuya Fushimi
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Makiko Tajika
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Keiko Ichimoto
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Ayako Matsunaga
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Tomoko Tsuruoka
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan
| | - Mika Ishige
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Tatsuo Fuchigami
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Taro Yamazaki
- Department of Pediatrics, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan
| | - Masato Mori
- Department of Pediatrics, Matsudo City Hospital, Matsudo, 4005 Kamihongo, Matsudo, Chiba, 271-8511, Japan
| | - Masakazu Kohda
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
| | - Yoshihito Kishita
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
| | - Yasushi Okazaki
- Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
- Division of Functional Genomics and Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, 1397-1 Yamane, Hidaka, Saitama, 350-1241, Japan
| | - Shori Takahashi
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Ohyaguchikami-cho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, 38 Morohongo, Moroyama, Saitama, 350-0495, Japan.
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan.
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Zhou M, Wang M, Xue L, Lin Z, He Q, Shi W, Chen Y, Jin X, Li H, Jiang P, Guan MX. A hypertension-associated mitochondrial DNA mutation alters the tertiary interaction and function of tRNA Leu(UUR). J Biol Chem 2017; 292:13934-13946. [PMID: 28679533 DOI: 10.1074/jbc.m117.787028] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 07/03/2017] [Indexed: 01/10/2023] Open
Abstract
Several mitochondrial tRNA mutations have been associated with hypertension, but their pathophysiology remains poorly understood. In this report, we identified a novel homoplasmic 3253T→C mutation in the mitochondrial tRNALeu(UUR) gene in a Han Chinese family with maternally inherited hypertension. The m.3253T→C mutation affected a highly conserved uridine at position 22 at the D-stem of tRNALeu(UUR), introducing a G-C base pairing (G13-C22) at the D-stem and a tertiary base pairing (C22-G46) between the D-stem and the variable loop. We therefore hypothesized that the m.3253T→C mutation altered both the structure and function of tRNALeu(UUR) Using cytoplasmic hybrid (cybrid) cell lines derived from this Chinese family, we demonstrated that the m.3253T→C mutation perturbed the conformation and stability of tRNALeu(UUR), as suggested by faster electrophoretic mobility of mutated tRNA relative to the wild-type molecule. Northern blot analysis revealed an ∼45% decrease in the steady-state level of tRNALeu(UUR) in the mutant cell lines carrying the m.3253T→C mutation, as compared with control cell lines. Moreover, an ∼35% reduction in aminoacylation efficiency of tRNALeu(UUR) was observed in the m.3253T→C mutant cells. These alterations in tRNALeu(UUR) metabolism impaired mitochondrial translation, especially for those polypeptides with a high proportion of Leu(UUR) codons, such as ND6. Furthermore, we demonstrated that the m.3253T→C mutation decreased the activities of mitochondrial complexes I and V, markedly diminished mitochondrial ATP levels and membrane potential, and increased the production of reactive oxygen species in the cells. In conclusion, our findings may provide new insights into the pathophysiology of maternally inherited hypertension.
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Affiliation(s)
- Mi Zhou
- From the Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang, China,; Institute of Genetics and Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Meng Wang
- From the Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang, China,; Institute of Genetics and Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Ling Xue
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325600, Zhejiang, China
| | - Zhi Lin
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325600, Zhejiang, China
| | - Qiufen He
- Institute of Genetics and Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Wenwen Shi
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325600, Zhejiang, China
| | - Yaru Chen
- Attardi Institute of Mitochondrial Biomedicine, Wenzhou Medical University, Wenzhou 325600, Zhejiang, China
| | - Xiaofen Jin
- Institute of Genetics and Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Haiying Li
- Department of Cardiology, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325600, Zhejiang, China
| | - Pingping Jiang
- From the Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang, China,; Institute of Genetics and Zhejiang University, Hangzhou 310058, Zhejiang, China
| | - Min-Xin Guan
- From the Division of Medical Genetics and Genomics, Children's Hospital, Zhejiang University School of Medicine, Hangzhou 310058, Zhejiang, China,; Institute of Genetics and Zhejiang University, Hangzhou 310058, Zhejiang, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University, Hangzhou 310058, Zhejiang, China,; Joint Institute of Genetics and Genomic Medicine between Zhejiang University and University of Toronto, Hangzhou 310058, Zhejiang, China.
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Merz TM, Pereira AJ, Schürch R, Schefold JC, Jakob SM, Takala J, Djafarzadeh S. Mitochondrial function of immune cells in septic shock: A prospective observational cohort study. PLoS One 2017; 12:e0178946. [PMID: 28591158 PMCID: PMC5462395 DOI: 10.1371/journal.pone.0178946] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 05/22/2017] [Indexed: 12/14/2022] Open
Abstract
Background Reduced cellular ATP synthesis due to impaired mitochondrial function of immune cells may be a factor influencing the immune response in septic shock. We investigate changes in mitochondrial function and bioenergetics of human monocytes and lymphocyte subsets. Methods Thirty patients with septic shock were studied at ICU admission, after 24 and 48 hours, and after resolution of shock. Enzymatic activities of citrate synthase and mitochondrial complexes I, IV, and ATP synthase and ATP content of monocytes, T-cells and B-cells and pro-inflammatory (IL-1β and IL-6) and anti-inflammatory (IL-10) cytokine plasma concentrations were compared to samples from 20 healthy volunteers. Results Large variations in mitochondrial enzymatic activities of immune cells of septic patients were detected. In monocytes, maximum levels of citrate synthase activity in sepsis were significantly lower when compared to controls (p = 0.021). Maximum relative enzymatic activity (ratio relative to citrate synthase activity) of complex I (p<0.001), complex IV (p = 0.017) and ATP synthase (p<0.001) were significantly higher. In T-cells, maximum levels of citrate synthase (p = 0.583) and relative complex IV (p = 0.602) activity did not differ between patients and controls, whereas levels of relative complex I (p = 0.006) and ATP synthase (p = 0.032) were significantly higher in septic patients. In B-cells of patients, maximum levels of citrate synthase activity (p = 0.004) and relative complex I (p<0.001) were significantly higher, and mean levels of relative complex IV (p = 0.042) lower than the control values, whereas relative ATP synthase activity did not differ (p = 1.0). No significant difference in cellular ATP content was detected in any cell line (p = 0.142–0.519). No significant correlations between specific cytokines and parameters of mitochondrial enzymatic activities or ATP content were observed. Conclusions Significant changes of mitochondrial enzymatic activities occur in human peripheral blood immune cells in septic shock when compared to healthy controls. Assessed sub-types of immune cells showed differing patterns of regulation. Total ATP-content of human immune cells did not differ between patients in septic shock and healthy volunteers.
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Affiliation(s)
- Tobias M. Merz
- Department of Intensive Care Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland
- * E-mail:
| | - Adriano J. Pereira
- Department of Intensive Care Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland
| | - Roger Schürch
- Division of Statistics, Clinical Trials Unit, Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
| | - Joerg C. Schefold
- Department of Intensive Care Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland
| | - Stephan M. Jakob
- Department of Intensive Care Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland
| | - Jukka Takala
- Department of Intensive Care Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland
| | - Siamak Djafarzadeh
- Department of Intensive Care Medicine, Bern University Hospital, University of Bern, CH-3010 Bern, Switzerland
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30
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Connor TM, Hoer S, Mallett A, Gale DP, Gomez-Duran A, Posse V, Antrobus R, Moreno P, Sciacovelli M, Frezza C, Duff J, Sheerin NS, Sayer JA, Ashcroft M, Wiesener MS, Hudson G, Gustafsson CM, Chinnery PF, Maxwell PH. Mutations in mitochondrial DNA causing tubulointerstitial kidney disease. PLoS Genet 2017; 13:e1006620. [PMID: 28267784 PMCID: PMC5360345 DOI: 10.1371/journal.pgen.1006620] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/21/2017] [Accepted: 02/07/2017] [Indexed: 11/19/2022] Open
Abstract
Tubulointerstitial kidney disease is an important cause of progressive renal failure whose aetiology is incompletely understood. We analysed a large pedigree with maternally inherited tubulointerstitial kidney disease and identified a homoplasmic substitution in the control region of the mitochondrial genome (m.547A>T). While mutations in mtDNA coding sequence are a well recognised cause of disease affecting multiple organs, mutations in the control region have never been shown to cause disease. Strikingly, our patients did not have classical features of mitochondrial disease. Patient fibroblasts showed reduced levels of mitochondrial tRNAPhe, tRNALeu1 and reduced mitochondrial protein translation and respiration. Mitochondrial transfer demonstrated mitochondrial transmission of the defect and in vitro assays showed reduced activity of the heavy strand promoter. We also identified further kindreds with the same phenotype carrying a homoplasmic mutation in mitochondrial tRNAPhe (m.616T>C). Thus mutations in mitochondrial DNA can cause maternally inherited renal disease, likely mediated through reduced function of mitochondrial tRNAPhe.
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Affiliation(s)
| | - Simon Hoer
- Cambridge Institute for Medical Research, University of Cambridge, United Kingdom
| | - Andrew Mallett
- Kidney Health Service, Royal Brisbane and Women’s Hospital, School of Medicine, The University of Queensland, Australia
| | - Daniel P. Gale
- UCL Centre for Nephrology, Royal Free Hospital, London, United Kingdom
| | | | - Viktor Posse
- Institute of Biomedicine, University of Gothenburg, Sweden
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, United Kingdom
| | - Pablo Moreno
- Cambridge Institute for Medical Research, University of Cambridge, United Kingdom
| | | | | | - Jennifer Duff
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Neil S. Sheerin
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - John A. Sayer
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Michael S. Wiesener
- Department of Nephrology and Hypertension, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Gavin Hudson
- Institute of Genetic Medicine, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | | | - Patrick H. Maxwell
- School of Clinical Medicine, Cambridge University, Cambridge, United Kingdom
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31
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Friederich MW, Erdogan AJ, Coughlin CR, Elos MT, Jiang H, O’Rourke CP, Lovell MA, Wartchow E, Gowan K, Chatfield KC, Chick WS, Spector EB, Van Hove JL, Riemer J. Mutations in the accessory subunit NDUFB10 result in isolated complex I deficiency and illustrate the critical role of intermembrane space import for complex I holoenzyme assembly. Hum Mol Genet 2017; 26:702-716. [PMID: 28040730 PMCID: PMC6251674 DOI: 10.1093/hmg/ddw431] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/27/2016] [Accepted: 12/16/2016] [Indexed: 12/17/2022] Open
Abstract
An infant presented with fatal infantile lactic acidosis and cardiomyopathy, and was found to have profoundly decreased activity of respiratory chain complex I in muscle, heart and liver. Exome sequencing revealed compound heterozygous mutations in NDUFB10, which encodes an accessory subunit located within the PD part of complex I. One mutation resulted in a premature stop codon and absent protein, while the second mutation replaced the highly conserved cysteine 107 with a serine residue. Protein expression of NDUFB10 was decreased in muscle and heart, and less so in the liver and fibroblasts, resulting in the perturbed assembly of the holoenzyme at the 830 kDa stage. NDUFB10 was identified together with three other complex I subunits as a substrate of the intermembrane space oxidoreductase CHCHD4 (also known as Mia40). We found that during its mitochondrial import and maturation NDUFB10 transiently interacts with CHCHD4 and acquires disulfide bonds. The mutation of cysteine residue 107 in NDUFB10 impaired oxidation and efficient mitochondrial accumulation of the protein and resulted in degradation of non-imported precursors. Our findings indicate that mutations in NDUFB10 are a novel cause of complex I deficiency associated with a late stage assembly defect and emphasize the role of intermembrane space proteins for the efficient assembly of complex I.
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Affiliation(s)
- Marisa W. Friederich
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Alican J. Erdogan
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Curtis R. Coughlin
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Mihret T. Elos
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Hua Jiang
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Courtney P. O’Rourke
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Mark A. Lovell
- Department of Pathology, University of Colorado, Aurora, CO, USA
- Department of Pathology, Children’s Hospital of Colorado, Aurora, CO, USA
| | - Eric Wartchow
- Department of Pathology, University of Colorado, Aurora, CO, USA
- Department of Pathology, Children’s Hospital of Colorado, Aurora, CO, USA
| | - Katherine Gowan
- Department of Biochemistry and Molecular Genetics, University of Colorado, Aurora, CO, USA
| | - Kathryn C. Chatfield
- Department of Pediatrics, Section of Cardiology, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Wallace S. Chick
- Department of Cell and Developmental Biology, University of Colorado, Aurora, CO, USA
| | - Elaine B. Spector
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Johan L.K. Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, School of Medicine, Aurora, CO, USA
| | - Jan Riemer
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Cologne, Germany
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Hartman JH, Miller GP, Caro AA, Byrum SD, Orr LM, Mackintosh SG, Tackett AJ, MacMillan-Crow LA, Hallberg LM, Ameredes BT, Boysen G. 1,3-Butadiene-induced mitochondrial dysfunction is correlated with mitochondrial CYP2E1 activity in Collaborative Cross mice. Toxicology 2017; 378:114-124. [PMID: 28082109 DOI: 10.1016/j.tox.2017.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 12/16/2016] [Accepted: 01/04/2017] [Indexed: 01/04/2023]
Abstract
Cytochrome P450 2E1 (CYP2E1) metabolizes low molecular weight hydrophobic compounds, including 1,3-butadiene, which is converted by CYP2E1 to electrophilic epoxide metabolites that covalently modify cellular proteins and DNA. Previous CYP2E1 studies have mainly focused on the enzyme localized in the endoplasmic reticulum (erCYP2E1); however, active CYP2E1 has also been found in mitochondria (mtCYP2E1) and the distribution of CYP2E1 between organelles can influence an individual's response to exposure. Relatively few studies have focused on the contribution of mtCYP2E1 to activation of chemical toxicants. We hypothesized that CYP2E1 bioactivation of 1,3-butadiene within mitochondria adversely affects mitochondrial respiratory complexes I-IV. A population of Collaborative Cross mice was exposed to air (control) or 200ppm 1,3-butadiene. Subcellular fractions (mitochondria, DNA, and microsomes) were collected from frozen livers and CYP2E1 activity was measured in microsomes and mitochondria. Individual activities of mitochondrial respiratory complexes I-IV were measured using in vitro assays and purified mitochondrial fractions. In air- and 1,3-butadiene-exposed mouse samples, mtDNA copy numbers were assessed by RT-PCR, and mtDNA integrity was assessed through a PCR-based assay. No significant changes in mtDNA copy number or integrity were observed; however, there was a decrease in overall activity of mitochondrial respiratory complexes I, II, and IV after 1,3-butadiene exposure. Additionally, higher mtCYP2E1 (but not erCYP2E1) activity was correlated with decreased mitochondrial respiratory complex activity (in complexes I-IV) in the 1,3-butadiene-exposed (not control) animals. Together, these results represent the first in vivo link between mitochondrial CYP2E1 activity and mitochondrial toxicity.
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Affiliation(s)
- Jessica H Hartman
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Grover P Miller
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
| | - Andres A Caro
- Department of Chemistry, Hendrix College, Conway, AR, United States
| | - Stephanie D Byrum
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Lisa M Orr
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Samuel G Mackintosh
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Alan J Tackett
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Lee Ann MacMillan-Crow
- Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Lance M Hallberg
- Department of Preventive Medicine and Community Health, University of Texas Medical Branch, Galveston, TX, United States; Sealy Center for Environmental Health and Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Bill T Ameredes
- Sealy Center for Environmental Health and Medicine, University of Texas Medical Branch, Galveston, TX, United States; Division of Pulmonary, Critical Care, and Sleep Medicine, and Department of Pharmacology and Toxicology, United States
| | - Gunnar Boysen
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, AR, United States; The Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, AR, United States.
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Sun Z, Lan X, Ahsan A, Xi Y, Liu S, Zhang Z, Chu P, Song Y, Piao F, Peng J, Lin Y, Han G, Tang Z. Phosphocreatine protects against LPS-induced human umbilical vein endothelial cell apoptosis by regulating mitochondrial oxidative phosphorylation. Apoptosis 2016; 21:283-97. [PMID: 26708229 DOI: 10.1007/s10495-015-1210-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Phosphocreatine (PCr) is an exogenous energy substance, which provides phosphate groups for adenosine triphosphate (ATP) cycle and promotes energy metabolism in cells. However, it is still unclear whether PCr has influenced on mitochondrial energy metabolism as well as oxidative phosphorylation (OXPHO) in previous studies. Therefore, the aim of the present study was to investigate the regulation of PCr on lipopolsaccharide (LPS)-induced human umbilical vein endothelial cells (HUVECs) and mitochondrial OXPHO pathway. PCr protected HUVECs against LPS-induced apoptosis by suppressing the mitochondrial permeability transition, cytosolic release of cytochrome c (Cyt C), Ca(2+), reactive oxygen species and subsequent activation of caspases, and increasing Bcl2 expression, while suppressing Bax expression. More importantly, PCr significantly improved mitochondrial swelling and membrane potential, enhanced the activities of ATP synthase and mitochondrial creatine kinase (CKmt) in creatine shuttle, influenced on respiratory chain enzymes, respiratory control ratio, phosphorus/oxygen ratio and ATP production of OXPHO. Above PCr-mediated mitochondrial events were effectively more favorable to reduced form of flavin adenine dinucleotide (FADH2) pathway than reduced form of nicotinamide-adenine dinucleotid pathway in the mitochondrial respiratory chain. Our results revealed that PCr protects against LPS-induced HUVECs apoptosis, which probably related to stabilization of intracellular energy metabolism, especially for FADH2 pathway in mitochondrial respiratory chain, ATP synthase and CKmt. Our findings suggest that PCr may play a certain role in the treatment of atherosclerosis via protecting endothelial cell function.
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Affiliation(s)
- Zhengwu Sun
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China.,Pharmacy Department, Dalian Municipal Central Hospital, Dalian, China
| | - Xiaoyan Lan
- Neurology Department, Dalian Municipal Central Hospital, Dalian, China
| | - Anil Ahsan
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Yalin Xi
- Pharmacy Department, Dalian Municipal Central Hospital, Dalian, China
| | - Shumin Liu
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Zonghui Zhang
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Peng Chu
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Yushu Song
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Fengyuan Piao
- Public Health Department, Dalian Medical University, Dalian, China
| | - Jinyong Peng
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Yuan Lin
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Guozhu Han
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China
| | - Zeyao Tang
- Department of Pharmacology, Dalian Medical University, West Section 9, South Road of Lvshun, Dalian, 116044, China.
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Mitochondrial Encephalopathy and Optic Neuropathy Due to m.10158 MT-ND3 Complex I Mutation Presenting in an Adult Patient. Neurologist 2016; 21:61-5. [DOI: 10.1097/nrl.0000000000000084] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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35
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Nafisinia M, Guo Y, Dang X, Li J, Chen Y, Zhang J, Lake NJ, Gold WA, Riley LG, Thorburn DR, Keating B, Xu X, Hakonarson H, Christodoulou J. Whole Exome Sequencing Identifies the Genetic Basis of Late-Onset Leigh Syndrome in a Patient with MRI but Little Biochemical Evidence of a Mitochondrial Disorder. JIMD Rep 2016; 32:117-124. [PMID: 27344648 DOI: 10.1007/8904_2016_541] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 01/25/2016] [Accepted: 01/26/2016] [Indexed: 03/11/2023] Open
Abstract
Leigh syndrome is a subacute necrotising encephalomyopathy proven by post-mortem analysis of brain tissue showing spongiform lesions with vacuolation of the neuropil followed by demyelination, gliosis and capillary proliferation caused by mutations in one of over 75 different genes, including nuclear- and mitochondrial-encoded genes, most of which are associated with mitochondrial respiratory chain function. In this study, we report a patient with suspected Leigh syndrome presenting with seizures, ptosis, scoliosis, dystonia, symmetrical putaminal abnormalities and a lactate peak on brain MRS, but showing normal MRC enzymology in muscle and liver, thereby complicating the diagnosis. Whole exome sequencing uncovered compound heterozygous mutations in NADH dehydrogenase (ubiquinone) flavoprotein 1 gene (NDUFV1), c.1162+4A>C (NM_007103.3), resulting in skipping of exon 8, and c.640G>A, causing the amino acid substitution p.Glu214Lys, both of which have previously been reported in a patient with complex I deficiency. Patient fibroblasts showed a significant reduction in NDUFV1 protein expression, decreased complex CI and complex IV assembly and consequential reductions in the enzymatic activities of both complexes by 38% and 67%, respectively. The pathogenic effect of these variations was further confirmed by immunoblot analysis of subunits for MRC enzyme complexes in patient muscle, liver and fibroblast where we observed 90%, 60% and 95% reduction in complex CI, respectively. Together these studies highlight the importance of a comprehensive, multipronged approach to the laboratory evaluation of patients with suspected Leigh syndrome.
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Affiliation(s)
- Michael Nafisinia
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Locked Bag 4001, Sydney, NSW, 2145, Australia.,Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Yiran Guo
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Xiao Dang
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, 518083, China.,Shenzen Key Laboratory of Neurogenomics, BGI-Shenzen, Shenzhen, 518083, China
| | - Jiankang Li
- Shenzen Key Laboratory of Neurogenomics, BGI-Shenzen, Shenzhen, 518083, China
| | - Yulan Chen
- Shenzen Key Laboratory of Neurogenomics, BGI-Shenzen, Shenzhen, 518083, China
| | - Jianguo Zhang
- Shenzen Key Laboratory of Neurogenomics, BGI-Shenzen, Shenzhen, 518083, China
| | - Nicole J Lake
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Wendy A Gold
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Locked Bag 4001, Sydney, NSW, 2145, Australia.,Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Lisa G Riley
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Locked Bag 4001, Sydney, NSW, 2145, Australia.,Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - David R Thorburn
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Brendan Keating
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Xun Xu
- Shenzen Key Laboratory of Neurogenomics, BGI-Shenzen, Shenzhen, 518083, China
| | - Hakon Hakonarson
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - John Christodoulou
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Locked Bag 4001, Sydney, NSW, 2145, Australia. .,Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia. .,Discipline of Genetic Medicine, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
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Hautakangas MR, Hinttala R, Rantala H, Nieminen P, Uusimaa J, Hassinen IE. Evaluating clinical mitochondrial respiratory chain enzymes from biopsy specimens presenting skewed probability distribution of activity data. Mitochondrion 2016; 29:53-8. [PMID: 27223842 DOI: 10.1016/j.mito.2016.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 04/05/2016] [Accepted: 05/16/2016] [Indexed: 12/13/2022]
Abstract
Due to the relative rarity of mitochondrial diseases, generating reference ranges is problematic in evaluation of respiratory chain activities particularly in pediatric cases. We determined the sample distribution of respiratory chain enzyme activities in skeletal muscle biopsies collected from pediatric patients suspected of neuromuscular disorders. Activities of NADH-ubiquinone reductase, NADH-cytochrome c reductase, succinate-cytochrome c reductase; ubiquinol-cytochrome c reductase and cytochrome c oxidase activities have log-normal distributions even when confirmed mitochondrial diseases were ruled out. Impact of the log-normal distribution of the respiratory chain enzyme activities on clinical diagnostics is discussed.
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Affiliation(s)
- Milla-Riikka Hautakangas
- PEDEGO Research Unit and Medical Research Center Oulu, University of Oulu, Finland; Department of Children and Adolescents, Division of Pediatric Neurology, Oulu University Hospital, Finland.
| | - Reetta Hinttala
- PEDEGO Research Unit and Medical Research Center Oulu, University of Oulu, Finland; Department of Children and Adolescents, Division of Pediatric Neurology, Oulu University Hospital, Finland.
| | - Heikki Rantala
- PEDEGO Research Unit and Medical Research Center Oulu, University of Oulu, Finland; Department of Children and Adolescents, Division of Pediatric Neurology, Oulu University Hospital, Finland.
| | - Pentti Nieminen
- Medical Informatics and Statistics Group, University of Oulu, Finland.
| | - Johanna Uusimaa
- PEDEGO Research Unit and Medical Research Center Oulu, University of Oulu, Finland; Department of Children and Adolescents, Division of Pediatric Neurology, Oulu University Hospital, Finland.
| | - Ilmo E Hassinen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland.
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Measurement of Systemic Mitochondrial Function in Advanced Primary Open-Angle Glaucoma and Leber Hereditary Optic Neuropathy. PLoS One 2015; 10:e0140919. [PMID: 26496696 PMCID: PMC4619697 DOI: 10.1371/journal.pone.0140919] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 10/01/2015] [Indexed: 11/18/2022] Open
Abstract
Primary Open Angle Glaucoma (POAG) is a common neurodegenerative disease characterized by the selective and gradual loss of retinal ganglion cells (RGCs). Aging and increased intraocular pressure (IOP) are glaucoma risk factors; nevertheless patients deteriorate at all levels of IOP, implying other causative factors. Recent evidence presents mitochondrial oxidative phosphorylation (OXPHOS) complex-I impairments in POAG. Leber Hereditary Optic Neuropathy (LHON) patients suffer specific and rapid loss of RGCs, predominantly in young adult males, due to complex-I mutations in the mitochondrial genome. This study directly compares the degree of OXPHOS impairment in POAG and LHON patients, testing the hypothesis that the milder clinical disease in POAG is due to a milder complex-I impairment. To assess overall mitochondrial capacity, cells can be forced to produce ATP primarily from mitochondrial OXPHOS by switching the media carbon source to galactose. Under these conditions POAG lymphoblasts grew 1.47 times slower than controls, whilst LHON lymphoblasts demonstrated a greater degree of growth impairment (2.35 times slower). Complex-I enzyme specific activity was reduced by 18% in POAG lymphoblasts and by 29% in LHON lymphoblasts. We also assessed complex-I ATP synthesis, which was 19% decreased in POAG patients and 17% decreased in LHON patients. This study demonstrates both POAG and LHON lymphoblasts have impaired complex-I, and in the majority of aspects the functional defects in POAG were milder than LHON, which could reflect the milder disease development of POAG. This new evidence places POAG in the spectrum of mitochondrial optic neuropathies and raises the possibility for new therapeutic targets aimed at improving mitochondrial function.
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Goldenthal MJ, Damle S, Sheth S, Shah N, Melvin J, Jethva R, Hardison H, Marks H, Legido A. Mitochondrial enzyme dysfunction in autism spectrum disorders; a novel biomarker revealed from buccal swab analysis. Biomark Med 2015; 9:957-65. [PMID: 26439018 DOI: 10.2217/bmm.15.72] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIM Mitochondrial function studies in autism spectrum disorders (ASD) have detected skeletal muscle mitochondrial enzyme deficiencies in respiratory complex (RC) activities. As a muscle biopsy is expensive and invasive, we assessed RC-I and RC-IV activities in buccal swabs. METHODS 92 children with ASD and 68 controls were studied with immunocapture for RC-I and microspectrophotometry for RC-IV. RESULTS Significant RC activity deficiencies were found in 39 (42%) ASD patients (p < 0.01) and more prevalent in more severe cases. Aberrant RC overactivity was seen in 9 children. RC-I/RC-IV activity ratio was significantly increased in 64% of the entire ASD cohort including 76% of those more severely affected (p < 0.05). CONCLUSION Buccal swab analysis revealed extensive RC abnormalities in ASD providing a noninvasive biomarker to assess mitochondrial function in ASD patients.
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Affiliation(s)
- Michael J Goldenthal
- Mitochondrial Disease Laboratory, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA.,Section of Neurology, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
| | - Shirish Damle
- Mitochondrial Disease Laboratory, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
| | - Sudip Sheth
- Mitochondrial Disease Laboratory, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
| | - Nidhi Shah
- Mitochondrial Disease Laboratory, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
| | - Joseph Melvin
- Section of Neurology, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
| | - Reena Jethva
- Section of Neurology, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
| | - Huntley Hardison
- Section of Neurology, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
| | - Harold Marks
- The Center for Neurological and Neurodevelopmental Health, Gibbsboro, NJ, USA
| | - Agustin Legido
- Section of Neurology, St. Christopher's Hospital for Children, Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA 19134, USA
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Miles L, Greiner HM, Mangano FT, Horn PS, Leach JL, Miles MV. Cytochrome c oxidase deficit is associated with the seizure onset zone in young patients with focal cortical dysplasia Type II. Metab Brain Dis 2015; 30:1151-60. [PMID: 25957585 DOI: 10.1007/s11011-015-9680-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/04/2015] [Indexed: 12/12/2022]
Abstract
It has been postulated that mitochondrial dysfunction may be an important factor in epileptogenesis of intractable epilepsy. The current study tests the hypothesis that mitochondrial Complex IV (CIV) or cytochrome c oxidase dysfunction is associated with the seizure onset zone (SOZ) in patients with focal cortical dysplasia (FCD). Subjects were selected based on: age <19y; epilepsy surgery between May, 2010 and October, 2011; pathological diagnosis of isolated focal cortical dysplasia Type I (FCDI) or Type II (FCDII); and sufficient residual cortical tissue to conduct analysis of electron transport chain complex (ETC) activity in SOZ and adjacent cortical regions. In this retrospective study, patients were identified who had sufficient unfixed, frozen brain tissue for biochemical analysis in tissue homogenates. Specimens were subtyped using ILAE classification for FCD, and excluded if diagnosed with FCD Type III or dual pathology. Analysis of ETC activity in resected tissues was conducted independently and without knowledge of the identity, diagnosis, or clinical status of individual subjects. Seventeen patients met the inclusion criteria, including 6 FCDI and 11 FCDII. Comparison of adjacent cortical resections showed decreased CIV activity in the SOZ of the FCDII group (P = 0.003), but no significant CIV difference in adjacent tissues of the FCDI group. Because of the importance of CIV as the terminal and rate-limiting complex in the mitochondrial electron transport chain, these authors conclude that 1) a deficit of CIV is associated with the SOZ of patients with FCDII; 2) CIV deficiency may contribute to the spectrum of FCD neuropathology; and 3) further investigation of CIV in FCD may lead to the discovery of new targets for neuroprotective therapies for patients with intractable epilepsy.
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Affiliation(s)
- Lili Miles
- Division of Pathology and Laboratory Medicine, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229, USA,
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Abstract
Rhabdomyolysis is characterized by severe acute muscle injury resulting in muscle pain, weakness, and/or swelling with release of myofiber contents into the bloodstream. Symptoms develop over hours to days after an inciting factor and may be associated with dark pigmentation of the urine. Serum creatine kinase and urine myoglobin levels are markedly elevated. Clinical examination, history, laboratory studies, muscle biopsy, and genetic testing are useful tools for diagnosis of rhabdomyolysis, and they can help differentiate acquired from inherited causes of rhabdomyolysis. Acquired causes include substance abuse, medication or toxic exposures, electrolyte abnormalities, endocrine disturbances, and autoimmune myopathies. Inherited predisposition to rhabdomyolysis can occur with disorders of glycogen metabolism, fatty acid β-oxidation, and mitochondrial oxidative phosphorylation. Less common inherited causes of rhabdomyolysis include structural myopathies, channelopathies, and sickle-cell disease. This review focuses on the differentiation of acquired and inherited causes of rhabdomyolysis and proposes a practical diagnostic algorithm. Muscle Nerve 51: 793-810, 2015.
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Affiliation(s)
- Jessica R Nance
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Andrew L Mammen
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Building 50, Room 1146, Bethesda, Maryland, 20892, USA
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41
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Guo Y, Menezes MJ, Menezes MP, Liang J, Li D, Riley LG, Clarke NF, Andrews PI, Tian L, Webster R, Wang F, Liu X, Shen Y, Thorburn DR, Keating BJ, Engel A, Hakonarson H, Christodoulou J, Xu X. Delayed diagnosis of congenital myasthenia due to associated mitochondrial enzyme defect. Neuromuscul Disord 2014; 25:257-61. [PMID: 25557462 DOI: 10.1016/j.nmd.2014.11.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 11/15/2014] [Accepted: 11/24/2014] [Indexed: 11/18/2022]
Abstract
Clinical phenotypes of congenital myasthenic syndromes and primary mitochondrial disorders share significant overlap in their clinical presentations, leading to challenges in making the correct diagnosis. Next generation sequencing is transforming molecular diagnosis of inherited neuromuscular disorders by identifying novel disease genes and by identifying previously known genes in undiagnosed patients. This is evident in two patients who were initially suspected to have a mitochondrial myopathy, but in whom a clear diagnosis of congenital myasthenic syndromes was made through whole exome sequencing. In patient 1, whole exome sequencing revealed compound heterozygous mutations c.1228C > T (p.Arg410Trp) and c.679C > T (p.Arg227*) in collagen-like tail subunit (single strand of homotrimer) of asymmetric acetylcholinesterase (COLQ). In patient 2, in whom a deletion of exon 52 in Dystrophin gene was previously detected by multiplex ligation-dependent probe amplification, Sanger sequencing revealed an additional homozygous mutation c.1511_1513delCTT (p.Pro504Argfs*183) in docking protein7 (DOK7). These case reports highlight the need for careful diagnosis of clinically heterogeneous syndromes like congenital myasthenic syndromes, which are treatable, and for which delayed diagnosis is likely to have implications for patient health. The report also demonstrates that whole exome sequencing is an effective diagnostic tool in providing molecular diagnosis in patients with complex phenotypes.
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Affiliation(s)
- Yiran Guo
- The Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Minal J Menezes
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics & Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Manoj P Menezes
- Discipline of Paediatrics & Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | | | - Dong Li
- The Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Lisa G Riley
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Nigel F Clarke
- Discipline of Paediatrics & Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - P Ian Andrews
- Department of Neurology, Sydney Children's Hospital, Randwick, NSW, Australia
| | - Lifeng Tian
- The Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | - Richard Webster
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Fengxiang Wang
- The Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
| | | | | | - David R Thorburn
- Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, VIC, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Brendan J Keating
- The Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States; Department of Pediatrics, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States; Department of Human Genetics Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - Andrew Engel
- Department of Neurology, Mayo Clinic, Rochester, MN, United States
| | - Hakon Hakonarson
- The Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States; Department of Pediatrics, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States; Department of Human Genetics Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - John Christodoulou
- Genetic Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney, NSW, Australia; Discipline of Paediatrics & Child Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia; Discipline of Genetic Medicine, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
| | - Xun Xu
- BGI-Shenzhen, Shenzhen 518083, China; The Guangdong Enterprise Key Laboratory of Human Disease Genomics, BGI-Shenzhen, Shenzhen, China
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Yamazaki T, Murayama K, Compton AG, Sugiana C, Harashima H, Amemiya S, Ajima M, Tsuruoka T, Fujinami A, Kawachi E, Kurashige Y, Matsushita K, Wakiguchi H, Mori M, Iwasa H, Okazaki Y, Thorburn DR, Ohtake A. Molecular diagnosis of mitochondrial respiratory chain disorders in Japan: focusing on mitochondrial DNA depletion syndrome. Pediatr Int 2014; 56:180-7. [PMID: 24266892 DOI: 10.1111/ped.12249] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 08/19/2013] [Accepted: 10/21/2013] [Indexed: 01/08/2023]
Abstract
BACKGROUND Although mitochondrial respiratory chain disorders (MRCD) are one of the most common congenital metabolic diseases, there is no cumulative data on enzymatic diagnosis and clinical manifestation for MRCD in Japan and Asia. METHODS We evaluated 675 Japanese patients having profound lactic acidemia, or patients having symptoms or signs of multiple-organ origin simultaneously without lactic acidemia on respiratory chain enzyme activity assay and blue native polyacrylamide gel electrophoresis. Quantitative polymerase chain reaction was used to diagnose mitochondrial DNA depletion syndrome (MTDPS). Mutation analysis of several genes responsible for MTDPS was also performed. RESULTS A total of 232 patients were diagnosed with a probable or definite MRCD. MRCD are common, afflicting one in every several thousand people in Japan. More than one in 10 of the patients diagnosed lacked lactic acidemia. A subsequent analysis of the causative genes of MTDPS identified novel mutations in six of the patients. A 335 bp deletion in deoxyguanosine kinase (DGUOK; g.11692_12026del335 (p.A48fsX90)) was noted in two unrelated families, and may therefore be a common mutation in Japanese people. The proportion of all patients with MTDPS, and particularly those with recessive DNA polymerase γ (POLG) mutations, appears to be lower in Japan than in other studies. This is most likely due to the relatively high prevalence of ancient European POLG mutations in Caucasian populations. No other significant differences were identified in a comparison of the enzymatic diagnoses, disease classifications or prognoses in Japanese and Caucasian patients with MRCD. CONCLUSION MTDPS and other MRCD are common, but serious, diseases that occur across all races.
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Affiliation(s)
- Taro Yamazaki
- Department of Pediatrics, Faculty of Medicine, Saitama Medical University, Saitama, Japan; Murdoch Childrens Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, Melbourne, Australia
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Van Bergen NJ, Blake RE, Crowston JG, Trounce IA. Oxidative phosphorylation measurement in cell lines and tissues. Mitochondrion 2014; 15:24-33. [DOI: 10.1016/j.mito.2014.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 03/06/2014] [Accepted: 03/10/2014] [Indexed: 01/01/2023]
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Forbes JM, Ke BX, Nguyen TV, Henstridge DC, Penfold SA, Laskowski A, Sourris KC, Groschner LN, Cooper ME, Thorburn DR, Coughlan MT. Deficiency in mitochondrial complex I activity due to Ndufs6 gene trap insertion induces renal disease. Antioxid Redox Signal 2013; 19:331-43. [PMID: 23320803 DOI: 10.1089/ars.2012.4719] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
AIMS Defects in the activity of enzyme complexes of the mitochondrial respiratory chain are thought to be responsible for several disorders, including renal impairment. Gene mutations that result in complex I deficiency are the most common oxidative phosphorylation disorders in humans. To determine whether an abnormality in mitochondrial complex I per se is associated with development of renal disease, mice with a knockdown of the complex I gene, Ndufs6 were studied. RESULTS Ndufs6 mice had a partial renal cortical complex I deficiency; Ndufs6gt/gt, 32% activity and Ndufs6gt/+, 83% activity compared with wild-type mice. Both Ndufs6gt/+ and Ndufs6gt/gt mice exhibited hallmarks of renal disease, including albuminuria, urinary excretion of kidney injury molecule-1 (Kim-1), renal fibrosis, and changes in glomerular volume, with decreased capacity to generate mitochondrial ATP and superoxide from substrates oxidized via complex I. However, more advanced renal defects in Ndufs6gt/gt mice were observed in the context of a disruption in the inner mitochondrial electrochemical potential, 3-nitrotyrosine-modified mitochondrial proteins, increased urinary excretion of 15-isoprostane F2t, and up-regulation of antioxidant defence. Juvenile Ndufs6gt/gt mice also exhibited signs of early renal impairment with increased urinary Kim-1 excretion and elevated circulating cystatin C. INNOVATION We have identified renal impairment in a mouse model of partial complex I deficiency, suggesting that even modest deficits in mitochondrial respiratory chain function may act as risk factors for chronic kidney disease. CONCLUSION These studies identify for the first time that complex I deficiency as the result of interruption of Ndufs6 is an independent cause of renal impairment.
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Affiliation(s)
- Josephine M Forbes
- Glycation, Nutrition and Metabolism Laboratory, Baker IDI Heart & Diabetes Institute, Melbourne, Australia
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Lim SC, Friemel M, Marum JE, Tucker EJ, Bruno DL, Riley LG, Christodoulou J, Kirk EP, Boneh A, DeGennaro CM, Springer M, Mootha VK, Rouault TA, Leimkühler S, Thorburn DR, Compton AG. Mutations in LYRM4, encoding iron-sulfur cluster biogenesis factor ISD11, cause deficiency of multiple respiratory chain complexes. Hum Mol Genet 2013; 22:4460-73. [PMID: 23814038 DOI: 10.1093/hmg/ddt295] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Iron-sulfur clusters (ISCs) are important prosthetic groups that define the functions of many proteins. Proteins with ISCs (called iron-sulfur or Fe-S proteins) are present in mitochondria, the cytosol, the endoplasmic reticulum and the nucleus. They participate in various biological pathways including oxidative phosphorylation (OXPHOS), the citric acid cycle, iron homeostasis, heme biosynthesis and DNA repair. Here, we report a homozygous mutation in LYRM4 in two patients with combined OXPHOS deficiency. LYRM4 encodes the ISD11 protein, which forms a complex with, and stabilizes, the sulfur donor NFS1. The homozygous mutation (c.203G>T, p.R68L) was identified via massively parallel sequencing of >1000 mitochondrial genes (MitoExome sequencing) in a patient with deficiency of complexes I, II and III in muscle and liver. These three complexes contain ISCs. Sanger sequencing identified the same mutation in his similarly affected cousin, who had a more severe phenotype and died while a neonate. Complex IV was also deficient in her skeletal muscle. Several other Fe-S proteins were also affected in both patients, including the aconitases and ferrochelatase. Mutant ISD11 only partially complemented for an ISD11 deletion in yeast. Our in vitro studies showed that the l-cysteine desulfurase activity of NFS1 was barely present when co-expressed with mutant ISD11. Our findings are consistent with a defect in the early step of ISC assembly affecting a broad variety of Fe-S proteins. The differences in biochemical and clinical features between the two patients may relate to limited availability of cysteine in the newborn period and suggest a potential approach to therapy.
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Affiliation(s)
- Sze Chern Lim
- Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville, VIC 3052, Australia
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Goldstein A, Wolfe LA. The elusive magic pill: finding effective therapies for mitochondrial disorders. Neurotherapeutics 2013; 10:320-8. [PMID: 23355364 PMCID: PMC3625379 DOI: 10.1007/s13311-012-0175-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The incidence of mitochondrial diseases has been estimated at 11.5/100,000 (1:8500) worldwide. In the USA up to 4000 newborns annually are expected to develop a mitochondrial disease. More than 50 million adults in the USA also suffer from diseases in which primary or secondary mitochondrial dysfunction is involved. Mitochondrial dysfunction has been identified in cancer, infertility, diabetes, heart diseases, blindness, deafness, kidney disease, liver disease, stroke, migraine, dwarfism, and resulting from numerous medication toxicities. Mitochondrial dysfunction is also involved in normal aging and age-related neurodegenerative diseases, such as Parkinson and Alzheimer diseases. Yet most treatments available are based on empiric data and clinician experience because of the lack of randomized controlled clinical trials to provide evidence-based treatments for these disorders. Here we explore the current state of research for the treatment of mitochondrial disorders.
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Affiliation(s)
- Amy Goldstein
- />Division of Child Neurology, Childrens Hospital of Pittsburgh of UPMC, Pittsburgh, PA USA
| | - Lynne A. Wolfe
- />Undiagnosed Diseases Program, National Institutes of Health, 10 Center DR, MSC 1205, RM# 3-2551, Bethesda, MD 20892 USA
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Fam HK, Chowdhury MK, Walton C, Choi K, Boerkoel CF, Hendson G. Expression profile and mitochondrial colocalization of Tdp1 in peripheral human tissues. J Mol Histol 2013; 44:481-94. [PMID: 23536040 DOI: 10.1007/s10735-013-9496-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/11/2013] [Indexed: 10/27/2022]
Abstract
Tyrosyl-DNA phosphodiesterase 1 (Tdp1) is a DNA repair enzyme that processes blocked 3' ends of DNA breaks. Functional loss of Tdp1 causes spinocerebellar ataxia with axonal neuropathy type 1 (SCAN1). Based on the prominent cytoplasmic expression of Tdp1 in the neurons presumably affected in SCAN1, we hypothesized that Tdp1 participates in the repair of mitochondrial DNA. As a step toward testing this hypothesis, we profiled Tdp1 expression in different human tissues by immunohistochemistry and immunofluorescence respectively and determined whether Tdp1 was expressed in the cytoplasm of tissues other than the neurons. We found that Tdp1 was ubiquitously expressed and present in the cytoplasm of many cell types. Within human skeletal muscle and multiple mouse tissues, Tdp1 partially colocalized with the mitochondria. In cultured human dermal fibroblasts, Tdp1 redistributed to the cytoplasm and partially colocalized with mitochondria following oxidative stress. These studies suggest that one role of cytoplasmic Tdp1 is the repair of mitochondrial DNA lesions arising from oxidative stress.
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Affiliation(s)
- Hok Khim Fam
- Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, BC, V5Z 4H4, Canada
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Murad NAA, Cullen JK, McKenzie M, Ryan MT, Thorburn D, Gueven N, Kobayashi J, Birrell G, Yang J, Dörk T, Becherel O, Grattan-Smith P, Lavin MF. Mitochondrial dysfunction in a novel form of autosomal recessive ataxia. Mitochondrion 2012. [PMID: 23178371 DOI: 10.1016/j.mito.2012.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Defects in the recognition and/or repair of damage to DNA are responsible for a sub-group of autosomal recessive ataxias. Included in this group is a novel form of ataxia with oculomotor apraxia characterised by sensitivity to DNA damaging agents, a defect in p53 stabilisation, oxidative stress and resistance to apoptosis. We provide evidence here that the defect in this patient's cells is at the level of the mitochondrion. Mitochondrial membrane potential was markedly reduced in cells from the patient and ROS levels were elevated. This was accompanied by lipid peroxidation of mitochondrial proteins involved in electron transport and RNA synthesis. However, no gross changes or alteration in composition or activity of mitochondrial electron transport complexes was evident. Sequencing of mitochondrial DNA revealed a mutation, I349T, in the mitochondrial cytochrome b gene. These results describe a patient with an apparently novel form of AOA characterised by a defect at the level of the mitochondrion.
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Affiliation(s)
- Nor Azian Abdul Murad
- Cancer and Cell Biology, Queensland Institute of Medical Research, Brisbane, Australia
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Ma YY, Wu TF, Liu YP, Wang Q, Li XY, Zhang Y, Song JQ, Wang YJ, Yang YL. Mitochondrial respiratory chain enzyme assay and DNA analysis in peripheral blood leukocytes for the etiological study of Chinese children with Leigh syndrome due to complex I deficiency. ACTA ACUST UNITED AC 2012; 24:67-73. [PMID: 22947169 DOI: 10.3109/19401736.2012.717932] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mitochondrial respiratory chain complex I enzyme deficiency is the most commonly seen mitochondrial respiratory chain disorder. Although screening and diagnostic methods are available overseas, clinically feasible diagnostic methods have not yet been established in China. In this study, four Chinese boys with Leigh syndrome due to complex I deficiency were diagnosed by mitochondrial respiratory chain enzyme assay and DNA analysis using peripheral blood leukocytes. Four patients were admitted at the age of 5-14 years because of unexplained progressive neuromuscular symptoms, including motor developmental delay or regression, weakness, and seizures. Their cranial magnetic resonance imaging revealed typical finding as Leigh syndrome. Peripheral leukocyte mitochondrial respiratory chain complex I activities were found decreased to 9.6-33.1 nmol/min/mg mitochondrial protein(control 44.0 ± 5.4 nmol/min/mg). The ratios of complex I to citrate synthase activity were also decreased (8.9-19.8% in patients vs. control 48 ± 11%). Three mtDNA mutations were identified from three out of four patients, supporting the diagnosis of complex I deficiency. Point mutations m.10191T>C in mitochondrial ND3 gene, m.13513G>A in ND5 gene and m.14,453G>A in ND6 gene were detected in three patients.
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Affiliation(s)
- Yan Yan Ma
- Department of Pediatrics, Peking University First Hospital , No. 1, Xi-an-men Road, Xicheng District, Beijing 100034 , P.R. China
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Quality improvement of mitochondrial respiratory chain complex enzyme assays using Caenorhabditis elegans. Genet Med 2012; 13:794-9. [PMID: 21633293 DOI: 10.1097/gim.0b013e31821afca5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE The diagnosis of a mitochondrial disorder relies heavily on the enzymatic analysis of mitochondrial respiratory chain complexes in muscle or other tissues. However, considerable differences exist between clinical laboratories in the protocols or particular tests used for evaluation. In addition, laboratories can encounter difficulties in consistent technique, as well as procurement of adequate positive or negative controls. Currently, there is no external quality assurance for respiratory chain complex assays. In this study, we explored the use of Caenorhabditis elegans mitochondria as a potential aid to diagnostic centers that perform respiratory chain complex assays. METHOD Five diagnostic test centers in the United States and one from Australia comparatively analyzed enzyme activities of mitochondria from C. elegans. The first survey consisted of three open-labeled samples including one normal control and two mutants; the second survey consisted of one open-labeled normal control and two blinded samples. RESULTS There was very good concordance among laboratories in detecting the majority of the defects present in the mutant specimens. Despite the ability to detect respiratory chain complex defects, the scatter between centers for certain enzymatic assays, particularly I + III, II, III, and IV, led to different diagnostic interpretations between the centers. CONCLUSION The data strongly support the need for comparative testing of mitochondrial enzyme assays between multiple laboratories. Our overall results are encouraging for the use of nematode mitochondria as a tool that might provide a virtually inexhaustible supply of mitochondria with defined defects for development of assays and as a potential source of control specimens.
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