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Ghosh Dastidar R, Banerjee S, Lal PB, Ghosh Dastidar S. Multifaceted Roles of AFG3L2, a Mitochondrial ATPase in Relation to Neurological Disorders. Mol Neurobiol 2023:10.1007/s12035-023-03768-z. [PMID: 38012514 DOI: 10.1007/s12035-023-03768-z] [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: 09/09/2023] [Accepted: 11/01/2023] [Indexed: 11/29/2023]
Abstract
AFG3L2 is a zinc metalloprotease and an ATPase localized in an inner mitochondrial membrane involved in mitochondrial quality control of several nuclear- and mitochondrial-encoded proteins. Mutations in AFG3L2 lead to diseases like slow progressive ataxia, which is a neurological disorder. This review delineates the cellular functions of AFG3L2 and its dysfunction that leads to major clinical outcomes, which include spinocerebellar ataxia type 28, spastic ataxia type 5, and optic atrophy type 12. It summarizes all relevant AFG3L2 mutations associated with the clinical outcomes to understand the detailed mechanisms attributable to its structure-related multifaceted roles in proteostasis and quality control. We face early diagnostic challenges of ataxia and optic neuropathy due to asymptomatic parents and variable clinical manifestations due to heterozygosity/homozygosity of AFG3L2 mutations. This review intends to promote AFG3L2 as a putative prognostic or diagnostic marker. Functions, mutations, and clinical manifestations in AFG3L2, a mitochondrial AAA + ATPases.
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Affiliation(s)
- Ranita Ghosh Dastidar
- Department of Biochemistry, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India.
| | - Saradindu Banerjee
- Centre for Molecular Neurosciences, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India
| | - Piyush Behari Lal
- Department of Microbiology, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India.
| | - Somasish Ghosh Dastidar
- Centre for Molecular Neurosciences, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Madhava Nagar, Manipal, 576104, Karnataka, India.
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Reyes NGD, Sepúlveda Soto MC, Munhoz RP. Spasmodic Dysphonia in a Patient with Spinocerebellar Ataxia Associated with a Rare AFG3L2 Variant (ATX- AFG3L2). Mov Disord Clin Pract 2023; 10:1024-1026. [PMID: 37332640 PMCID: PMC10272910 DOI: 10.1002/mdc3.13745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 03/03/2023] [Accepted: 04/02/2023] [Indexed: 04/08/2023] Open
Affiliation(s)
- Nikolai Gil D. Reyes
- Edmond J. Safra Program in Parkinson's Disease and the Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western HospitalTorontoOntarioCanada
| | - Maria Carolina Sepúlveda Soto
- Edmond J. Safra Program in Parkinson's Disease and the Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western HospitalTorontoOntarioCanada
| | - Renato P. Munhoz
- Edmond J. Safra Program in Parkinson's Disease and the Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western HospitalTorontoOntarioCanada
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Jin T, Kuang Y, Luo S, Wang R, Chen K, Jiang M, Ren L, Sun Z, Duan L, Huang S. Novel compound heterozygous mutations in the AFG3L2 gene in a Chinese child with microcephaly, early-onset seizures, and cerebral atrophy. Heliyon 2023; 9:e14766. [PMID: 37025825 PMCID: PMC10070717 DOI: 10.1016/j.heliyon.2023.e14766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/04/2023] [Accepted: 03/16/2023] [Indexed: 03/29/2023] Open
Abstract
Background The most common disease caused by biallelic AFG3L2 mutations is spastic ataxia type 5 (SPAX5). Identification of complex phenotypes resulting from biallelic AFG3L2 mutations has been increasing in recent years. Methods A retrospective analysis was performed on a child with microcephaly and recurrent seizures. The child underwent physical and neurological examinations, laboratory tests, electroencephalography (EEG), and brain magnetic resonance imaging (MRI). Trio-whole-exome sequencing (trio-WES) was performed to identify possible causative mutations. Results We described a child who exhibited early-onset and intractable epilepsy, developmental regression, microcephaly, and premature death. Neuroimaging revealed global cerebral atrophy (GCA) involving the cerebrum, cerebellum, corpus callosum, brainstem, cerebellar vermis, and basal ganglia. On trio-WES, two novel compound heterozygous mutations, c.1834G > T (p.E612*) and c.2176-6T > A in the AFG3L2 gene, were identified in this patient. Conclusions Our findings have expanded the mutation spectrum of the AFG3L2 gene and identified a severe neurodegenerative phenotype of global cerebral atrophy caused by biallelic AFG3L2 mutations.
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Affiliation(s)
- Tingting Jin
- School of Medicine, Guizhou University, Guiyang, Guizhou 550025, China
- Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
| | - Ying Kuang
- Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
| | - Shulin Luo
- Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
| | - Rongpin Wang
- Department of Radiology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
| | - Kun Chen
- Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
| | - Minmin Jiang
- Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
| | - Lingyan Ren
- Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
| | - Zhaolin Sun
- School of Medicine, Guizhou University, Guiyang, Guizhou 550025, China
- Department of Urology, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
- Corresponding author. School of Medicine, Guizhou University, Guiyang, Guizhou 550025, China.
| | - Lifen Duan
- Epilepsy Center, Children's Hospital Affiliated of Kunming Medical University, Kunming, Yunnan 650000, China
- Corresponding author.
| | - Shengwen Huang
- Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
- NHC Key Laboratory of Pulmonary Immunological Diseases, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China
- Corresponding author. Prenatal Diagnosis Center, Guizhou Provincial People's Hospital, Guiyang, Guizhou 550002, China.
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Wortmann SB, Oud MM, Alders M, Coene KLM, van der Crabben SN, Feichtinger RG, Garanto A, Hoischen A, Langeveld M, Lefeber D, Mayr JA, Ockeloen CW, Prokisch H, Rodenburg R, Waterham HR, Wevers RA, van de Warrenburg BPC, Willemsen MAAP, Wolf NI, Vissers LELM, van Karnebeek CDM. How to proceed after "negative" exome: A review on genetic diagnostics, limitations, challenges, and emerging new multiomics techniques. J Inherit Metab Dis 2022; 45:663-681. [PMID: 35506430 PMCID: PMC9539960 DOI: 10.1002/jimd.12507] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 11/28/2022]
Abstract
Exome sequencing (ES) in the clinical setting of inborn metabolic diseases (IMDs) has created tremendous improvement in achieving an accurate and timely molecular diagnosis for a greater number of patients, but it still leaves the majority of patients without a diagnosis. In parallel, (personalized) treatment strategies are increasingly available, but this requires the availability of a molecular diagnosis. IMDs comprise an expanding field with the ongoing identification of novel disease genes and the recognition of multiple inheritance patterns, mosaicism, variable penetrance, and expressivity for known disease genes. The analysis of trio ES is preferred over singleton ES as information on the allelic origin (paternal, maternal, "de novo") reduces the number of variants that require interpretation. All ES data and interpretation strategies should be exploited including CNV and mitochondrial DNA analysis. The constant advancements in available techniques and knowledge necessitate the close exchange of clinicians and molecular geneticists about genotypes and phenotypes, as well as knowledge of the challenges and pitfalls of ES to initiate proper further diagnostic steps. Functional analyses (transcriptomics, proteomics, and metabolomics) can be applied to characterize and validate the impact of identified variants, or to guide the genomic search for a diagnosis in unsolved cases. Future diagnostic techniques (genome sequencing [GS], optical genome mapping, long-read sequencing, and epigenetic profiling) will further enhance the diagnostic yield. We provide an overview of the challenges and limitations inherent to ES followed by an outline of solutions and a clinical checklist, focused on establishing a diagnosis to eventually achieve (personalized) treatment.
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Affiliation(s)
- Saskia B. Wortmann
- Radboud Center for Mitochondrial and Metabolic Medicine, Department of PediatricsAmalia Children's Hospital, Radboud University Medical CenterNijmegenThe Netherlands
- University Children's Hospital, Paracelsus Medical UniversitySalzburgAustria
| | - Machteld M. Oud
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Department of Human GeneticsDonders Institute for Brain, Cognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Mariëlle Alders
- Department of Human GeneticsAmsterdam UMC, University of Amsterdam, Amsterdam Reproduction and Development Research InstituteAmsterdamThe Netherlands
| | - Karlien L. M. Coene
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Saskia N. van der Crabben
- Department of Human GeneticsAmsterdam University Medical Centers, University of AmsterdamAmsterdamThe Netherlands
| | - René G. Feichtinger
- University Children's Hospital, Paracelsus Medical UniversitySalzburgAustria
| | - Alejandro Garanto
- Radboud Center for Mitochondrial and Metabolic Medicine, Department of PediatricsAmalia Children's Hospital, Radboud University Medical CenterNijmegenThe Netherlands
- Department of PediatricsAmalia Children's Hospital, Radboud Institute for Molecular LifesciencesNijmegenThe Netherlands
- Department of Human GeneticsRadboud Institute for Molecular LifesciencesNijmegenThe Netherlands
| | - Alex Hoischen
- Department of Human Genetics, Department of Internal Medicine and Radboud Center for Infectious DiseasesRadboud Institute of Medical Life Sciences, Radboud University Medical CenterNijmegenthe Netherlands
| | - Mirjam Langeveld
- Department of Endocrinology and MetabolismAmsterdam University Medical Centers, location AMC, University of AmsterdamAmsterdamThe Netherlands
| | - Dirk Lefeber
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
- Department of Neurology, Donders Institute for BrainCognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Johannes A. Mayr
- University Children's Hospital, Paracelsus Medical UniversitySalzburgAustria
| | - Charlotte W. Ockeloen
- Department of Human GeneticsRadboud Institute for Molecular LifesciencesNijmegenThe Netherlands
| | - Holger Prokisch
- School of MedicineInstitute of Human Genetics, Technical University Munich and Institute of NeurogenomicsNeuherbergGermany
| | - Richard Rodenburg
- Radboud Center for Mitochondrial and Metabolic MedicineTranslational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical CenterNijmegenThe Netherlands
| | - Hans R. Waterham
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Laboratory Genetic Metabolic Diseases, Department of Clinical ChemistryAmsterdam University Medical Centers, location AMC, University of AmsterdamAmsterdamThe Netherlands
| | - Ron A. Wevers
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Bart P. C. van de Warrenburg
- Department of Neurology, Donders Institute for BrainCognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Michel A. A. P. Willemsen
- Departments of Pediatric Neurology and PediatricsAmalia Children's Hospital, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical CenterNijmegenThe Netherlands
| | - Nicole I. Wolf
- Amsterdam Leukodystrophy Center, Department of Child NeurologyEmma Children's Hospital, Amsterdam University Medical Centers, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Lisenka E. L. M. Vissers
- Department of Human GeneticsDonders Institute for Brain, Cognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Clara D. M. van Karnebeek
- Radboud Center for Mitochondrial and Metabolic Medicine, Department of PediatricsAmalia Children's Hospital, Radboud University Medical CenterNijmegenThe Netherlands
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Department of Human GeneticsAmsterdam UMC, University of Amsterdam, Amsterdam Reproduction and Development Research InstituteAmsterdamThe Netherlands
- Department of Pediatrics, Emma Center for Personalized MedicineAmsterdam University Medical Centers, Amsterdam, Amsterdam Genetics Endocrinology Metabolism Research Institute, University of AmsterdamAmsterdamThe Netherlands
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Liu X, Wang L, Chen J, Kang C, Li J. Spinocerebellar ataxia type 28 in a Chinese pedigree: A case report and literature review. Medicine (Baltimore) 2021; 100:e28008. [PMID: 34918652 PMCID: PMC8678014 DOI: 10.1097/md.0000000000028008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/11/2021] [Indexed: 01/05/2023] Open
Abstract
RATIONALE Spinocerebellar ataxia (SCA) is a common neurogenetic disease that mainly manifests as ataxia of posture, gait, and limbs, cerebellar dysarthria, and cerebellar and supranuclear eye movement disorders. SCA has been found to include many subtypes, which are mainly mapped to 2 genetic patterns: autosomal dominant cerebellar ataxia and autosomal recessive cerebellar ataxia. Molecular genetic diagnosis functions as a necessity in its clinical diagnosis and treatment. In preliminary clinical work, we identified a family of SCA28 with rare gene mutation. PATIENT CONCERNS There are 5 patients in this family. The proband is a 32 year-old male, he mainly manifest unsteady steps for more than 7 months. The daughter of his younger maternal uncle gradually had unsteady steps and unclear speech for 5 years. The proband's mother, uncle and grandfather had similar symptoms, but they all died. DIAGNOSIS After Brain magnetic resonance imaging, whole exome sequencing and Sanger validation, the patients presented a c.1852A > G missense mutation in the exon region of AFG3L2 gene. The other family members revealed no AFG3L2 mutations. SCA28 is the one uniquely caused by a pathogenic variation in the mitochondrial protein AFG3L2. Combined with the clinical manifestations, auxiliary examinations and sequencing results of the patients (III-3 and III-5), the diagnosis of SCA28 was suspected. INTERVENTIONS The patients did not receive any drug treatment and the proband receive rehabilitation treatment. OUTCOMES The symptoms of ataxia were still progressively aggravated. LESSONS Molecular genetic diagnosis is necessary for ataxia. We here report the case and review the literature.
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Ng KY, Richter U, Jackson CB, Seneca S, Battersby BJ. Translation of MT-ATP6 pathogenic variants reveals distinct regulatory consequences from the co-translational quality control of mitochondrial protein synthesis. Hum Mol Genet 2021; 31:1230-1241. [PMID: 34718584 PMCID: PMC9029222 DOI: 10.1093/hmg/ddab314] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 11/16/2022] Open
Abstract
Pathogenic variants that disrupt human mitochondrial protein synthesis are associated with a clinically heterogeneous group of diseases. Despite an impairment in oxidative phosphorylation being a common phenotype, the underlying molecular pathogenesis is more complex than simply a bioenergetic deficiency. Currently, we have limited mechanistic understanding on the scope by which a primary defect in mitochondrial protein synthesis contributes to organelle dysfunction. Since the proteins encoded in the mitochondrial genome are hydrophobic and need co-translational insertion into a lipid bilayer, responsive quality control mechanisms are required to resolve aberrations that arise with the synthesis of truncated and misfolded proteins. Here, we show that defects in the OXA1L-mediated insertion of MT-ATP6 nascent chains into the mitochondrial inner membrane are rapidly resolved by the AFG3L2 protease complex. Using pathogenic MT-ATP6 variants, we then reveal discrete steps in this quality control mechanism and the differential functional consequences to mitochondrial gene expression. The inherent ability of a given cell type to recognize and resolve impairments in mitochondrial protein synthesis may in part contribute at the molecular level to the wide clinical spectrum of these disorders.
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Affiliation(s)
- Kah Ying Ng
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Uwe Richter
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.,Wellcome Centre for Mitochondrial Research, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Christopher B Jackson
- Department of Biochemistry and Developmental Biology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Sara Seneca
- Center for Medical Genetics/Research Center Reproduction and Genetics, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
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Abstract
The term SCA refers to a phenotypically and genetically heterogeneous group of autosomal dominant spinocerebellar ataxias. Phenotypically they present as gait ataxia frequently in combination with dysarthria and oculomotor problems. Additional signs and symptoms are common and can include various pyramidal and extrapyramidal signs and intellectual impairment. Genetic causes of SCAs are either repeat expansions within disease genes or common mutations (point mutations, deletions, insertions etc.). Frequently the two types of mutations cause indistinguishable phenotypes (locus heterogeneity). This article focuses on SCAs caused by common mutations. It describes phenotype and genotype of the presently 27 types known and discusses the molecular pathogenesis in those 21 types where the disease gene has been identified. Apart from the dominant types, the article also summarizes findings in a variant caused by mutations in a mitochondrial gene. Possible common disease mechanisms are considered based on findings in the various SCAs described.
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Affiliation(s)
- Ulrich Müller
- Institute of Human Genetics, JLU-Gießen, Schlangenzahl 14, 35392, Giessen, Germany.
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Chiang HL, Fuh JL, Tsai YS, Soong BW, Liao YC, Lee YC. Expanding the phenotype of AFG3L2 mutations: Late-onset autosomal recessive spinocerebellar ataxia. J Neurol Sci 2021; 428:117600. [PMID: 34333379 DOI: 10.1016/j.jns.2021.117600] [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: 04/18/2021] [Revised: 06/28/2021] [Accepted: 07/25/2021] [Indexed: 10/20/2022]
Abstract
The AFG3L2 gene encodes AFG3-like protein 2, which is a subunit of human mitochondrial ATPases associated with various cellular protease activities (m-AAA). The clinical spectrum of AFG3L2 mutations is broad. Dominant AFG3L2 mutations can cause autosomal dominant spinocerebellar ataxia type 28 (SCA28), whereas biallelic AFG3L2 mutations may lead to spastic ataxia 5 (SPAX5). However, the role of AFG3L2 mutations in autosomal recessive spinocerebellar ataxia (SCAR) remains elusive. The aim of this study is to delineate the clinical features and spectrum of AFG3L2 mutations in a Taiwanese cohort with cerebellar ataxia. Mutational analyses of AFG3L2 were carried out by targeted resequencing in a cohort of 133 unrelated patients with molecularly undetermined cerebellar ataxia. We identified one single patient carrying compound heterozygous mutations in AFG3L2, p.[R632*];[V723M] (c.[1894C > T];[2167G > A]). The patient has suffered from apparently sporadic and slowly progressive cerebellar ataxia, ptosis, and ophthalmoparesis since age 55 years. These findings expand the clinical spectrum of AFG3L2 mutations and suggest a new subtype of late-onset SCAR caused by biallelic AFG3L2 mutations.
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Affiliation(s)
- Han-Lin Chiang
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Jong-Ling Fuh
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine. No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Yu-Shuen Tsai
- Center for Systems and Synthetic Biology, National Yang Ming Chiao Tung University, No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Bing-Wen Soong
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; Department of Neurology, Shuang Ho Hospital, Taipei Medical University, No.291, Zhongzheng Rd., Zhonghe District, New Taipei 23561, Taiwan; Taipei Neuroscience Institute, Taipei Medical University, 250 Wu-Hsing Street, Taipei, Taiwan
| | - Yi-Chu Liao
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine. No.155, Sec.2, Linong Street, Taipei, Taiwan
| | - Yi-Chung Lee
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, No.201, Sec.2, Shipai Rd., Beitou District, Taipei, Taiwan; School of Medicine, National Yang Ming Chiao Tung University College of Medicine, No.155, Sec.2, Linong Street, Taipei, Taiwan; Brain Research Center, National Yang Ming Chiao Tung University School of Medicine. No.155, Sec.2, Linong Street, Taipei, Taiwan.
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Robinson KJ, Watchon M, Laird AS. Aberrant Cerebellar Circuitry in the Spinocerebellar Ataxias. Front Neurosci 2020; 14:707. [PMID: 32765211 PMCID: PMC7378801 DOI: 10.3389/fnins.2020.00707] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 06/11/2020] [Indexed: 12/11/2022] Open
Abstract
The spinocerebellar ataxias (SCAs) are a heterogeneous group of neurodegenerative diseases that share convergent disease features. A common symptom of these diseases is development of ataxia, involving impaired balance and motor coordination, usually stemming from cerebellar dysfunction and neurodegeneration. For most spinocerebellar ataxias, pathology can be attributed to an underlying gene mutation and the impaired function of the encoded protein through loss or gain-of-function effects. Strikingly, despite vast heterogeneity in the structure and function of disease-causing genes across the SCAs and the cellular processes affected, the downstream effects have considerable overlap, including alterations in cerebellar circuitry. Interestingly, aberrant function and degeneration of Purkinje cells, the major output neuronal population present within the cerebellum, precedes abnormalities in other neuronal populations within many SCAs, suggesting that Purkinje cells have increased vulnerability to cellular perturbations. Factors that are known to contribute to perturbed Purkinje cell function in spinocerebellar ataxias include altered gene expression resulting in altered expression or functionality of proteins and channels that modulate membrane potential, downstream impairments in intracellular calcium homeostasis and changes in glutamatergic input received from synapsing climbing or parallel fibers. This review will explore this enhanced vulnerability and the aberrant cerebellar circuitry linked with it in many forms of SCA. It is critical to understand why Purkinje cells are vulnerable to such insults and what overlapping pathogenic mechanisms are occurring across multiple SCAs, despite different underlying genetic mutations. Enhanced understanding of disease mechanisms will facilitate the development of treatments to prevent or slow progression of the underlying neurodegenerative processes, cerebellar atrophy and ataxic symptoms.
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Affiliation(s)
| | | | - Angela S. Laird
- Centre for Motor Neuron Disease Research, Department of Biomedical Science, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
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10
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Charif M, Chevrollier A, Gueguen N, Bris C, Goudenège D, Desquiret-Dumas V, Leruez S, Colin E, Meunier A, Vignal C, Smirnov V, Defoort-Dhellemmes S, Drumare Bouvet I, Goizet C, Votruba M, Jurkute N, Yu-Wai-Man P, Tagliavini F, Caporali L, La Morgia C, Carelli V, Procaccio V, Zanlonghi X, Meunier I, Reynier P, Bonneau D, Amati-Bonneau P, Lenaers G. Mutations in the m-AAA proteases AFG3L2 and SPG7 are causing isolated dominant optic atrophy. Neurol Genet 2020; 6:e428. [PMID: 32548275 PMCID: PMC7251510 DOI: 10.1212/nxg.0000000000000428] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 04/06/2020] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To improve the genetic diagnosis of dominant optic atrophy (DOA), the most frequently inherited optic nerve disease, and infer genotype-phenotype correlations. METHODS Exonic sequences of 22 genes were screened by new-generation sequencing in patients with DOA who were investigated for ophthalmology, neurology, and brain MRI. RESULTS We identified 7 and 8 new heterozygous pathogenic variants in SPG7 and AFG3L2. Both genes encode for mitochondrial matricial AAA (m-AAA) proteases, initially involved in recessive hereditary spastic paraplegia type 7 (HSP7) and dominant spinocerebellar ataxia 28 (SCA28), respectively. Notably, variants in AFG3L2 that result in DOA are located in different domains to those reported in SCA28, which likely explains the lack of clinical overlap between these 2 phenotypic manifestations. In comparison, the SPG7 variants identified in DOA are interspersed among those responsible for HSP7 in which optic neuropathy has previously been reported. CONCLUSIONS Our results position SPG7 and AFG3L2 as candidate genes to be screened in DOA and indicate that regulation of mitochondrial protein homeostasis and maturation by m-AAA proteases are crucial for the maintenance of optic nerve physiology.
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Affiliation(s)
- Majida Charif
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Arnaud Chevrollier
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Naïg Gueguen
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Céline Bris
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - David Goudenège
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Valérie Desquiret-Dumas
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Stéphanie Leruez
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Estelle Colin
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Audrey Meunier
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Catherine Vignal
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Vasily Smirnov
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Sabine Defoort-Dhellemmes
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Isabelle Drumare Bouvet
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Cyril Goizet
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Marcela Votruba
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Neringa Jurkute
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Patrick Yu-Wai-Man
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Francesca Tagliavini
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Leonardo Caporali
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Chiara La Morgia
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Valerio Carelli
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Vincent Procaccio
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Xavier Zanlonghi
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Isabelle Meunier
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Pascal Reynier
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Dominique Bonneau
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Patrizia Amati-Bonneau
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
| | - Guy Lenaers
- MitoLab Team (M.C., A.C., C.B., D.G., V.D.-D., S.L., V.P., P.R., D.B., P.A.-B., G.L.), UMR CNRS 6015-INSERM U1083, Institut MitoVasc, Angers University and Hospital; Genetics and immuno-cell therapy Team (M.C.), Mohammed First University, Oujda, Morocco; Departments of Biochemistry and Genetics (C.B., D.G., V.D.-D., E.C., V.P., P.R., D.B., P.A.-B.), University Hospital Angers; Department of Ophthalmology (A.M.), Centre Hospitalier Universitaire Saint-Pierre, Brussels, Belgium; Neuroophthalmology Department (C.V.), Rothschild Ophthalmologic Foundation, Paris; Exploration of Visual Function and Neuro-Ophthalmology Department (V.S., S.D.-D., I.D.B.), Lille University Hospital, Rue Emilie Laine, Lille Cedex; CHU Bordeaux (C.G.), Service de Génétique Médicale, Centre de Référence « Neurogénétique » and Université de Bordeaux, INSERM U 1211, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux; School of Optometry and Vision Sciences (M.V.), Cardiff University and Cardiff Eye Unit, University Hospital of Wales; NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology (N.J., P.Y.-W.-M.), London; Department of Clinical Neurosciences (P.Y.-W.-M.), Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge; Cambridge Eye Unit (P.Y.-W.-M.), Addenbrooke's Hospital, Cambridge University Hospitals, UK; IRCCS Istituto Delle Scienze Neurologiche di Bologna (F.T., L.C., C.L.M., V.C.), Bellaria Hospital; Unit of Neurology (C.L.M., V.C.), Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Italy; Centre de Compétence Maladies Rares (X.Z.), Clinique Pluridisciplinaire Jules Verne, Nantes; and National Centre in Rare Diseases (I.M.), Genetics of Sensory Diseases, University Hospital, Montpellier, France
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11
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Upregulation of Peroxiredoxin 3 Protects Afg3l2-KO Cortical Neurons In Vitro from Oxidative Stress: A Paradigm for Neuronal Cell Survival under Neurodegenerative Conditions. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:4721950. [PMID: 31781336 PMCID: PMC6875171 DOI: 10.1155/2019/4721950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/03/2019] [Accepted: 09/14/2019] [Indexed: 02/03/2023]
Abstract
Several neurodegenerative disorders exhibit selective vulnerability, with subsets of
neurons more affected than others, possibly because of the high expression of an altered
gene or the presence of particular features that make them more susceptible to insults. On
the other hand, resilient neurons may display the ability to develop antioxidant defenses,
particularly in diseases of mitochondrial origin, where oxidative stress might contribute
to the neurodegenerative process. In this work, we investigated the oxidative stress
response of embryonic fibroblasts and cortical neurons obtained from
Afg3l2-KO mice. AFG3L2 encodes a subunit of a protease
complex that is expressed in mitochondria and acts as both quality control and regulatory
enzyme affecting respiration and mitochondrial dynamics. When cells were subjected to an
acute oxidative stress protocol, the survival of AFG3L2-KO MEFs was not significantly
influenced and was comparable to that of WT; however, the basal level of the antioxidant
molecule glutathione was higher. Indeed, glutathione depletion strongly affected the
viability of KO, but not of WT MEF, thereby indicating that oxidative stress is more
elevated in KO MEF even though well controlled by glutathione. On the other hand, when
cortical KO neurons were put in culture, they immediately appeared more vulnerable than WT
to the acute oxidative stress condition, but after few days in vitro, the situation was
reversed with KO neurons being more resistant than WT to acute stress. This compensatory,
protective competence was not due to the upregulation of glutathione, rather of two
mitochondrial antioxidant proteins: superoxide dismutase 2 and, at an even higher level,
peroxiredoxin 3. This body of evidence sheds light on the capability of neurons to
activate neuroprotective pathways and points the attention to peroxiredoxin 3, an
antioxidant enzyme that might be critical for neuronal survival also in other disorders
affecting mitochondria.
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12
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Szpisjak L, Zadori D, Klivenyi P, Vecsei L. Clinical Characteristics and Possible Drug Targets in Autosomal Dominant Spinocerebellar Ataxias. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2019; 18:279-293. [DOI: 10.2174/1871527318666190311155846] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/10/2018] [Accepted: 01/31/2019] [Indexed: 12/28/2022]
Abstract
Background & Objective:
The autosomal dominant spinocerebellar ataxias (SCAs) belong
to a large and expanding group of neurodegenerative disorders. SCAs comprise more than 40 subtypes
characterized by progressive ataxia as a common feature. The most prevalent diseases among SCAs
are caused by CAG repeat expansions in the coding-region of the causative gene resulting in polyglutamine
(polyQ) tract formation in the encoded protein. Unfortunately, there is no approved therapy to
treat cerebellar motor dysfunction in SCA patients. In recent years, several studies have been conducted
to recognize the clinical and pathophysiological aspects of the polyQ SCAs more accurately.
This scientific progress has provided new opportunities to develop promising gene therapies, including
RNA interference and antisense oligonucleotides.
Conclusion:
The aim of the current work is to give a brief summary of the clinical features of SCAs
and to review the cardinal points of pathomechanisms of the most common polyQ SCAs. In addition,
we review the last few year’s promising gene suppression therapies of the most frequent polyQ SCAs
in animal models, on the basis of which human trials may be initiated in the near future.
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Affiliation(s)
- Laszlo Szpisjak
- Department of Neurology, University of Szeged, Szeged, Hungary
| | - Denes Zadori
- Department of Neurology, University of Szeged, Szeged, Hungary
| | - Peter Klivenyi
- Department of Neurology, University of Szeged, Szeged, Hungary
| | - Laszlo Vecsei
- Department of Neurology, University of Szeged, Szeged, Hungary
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13
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Spinocerebellar Ataxia Type 28—Phenotypic and Molecular Characterization of a Family with Heterozygous and Compound-Heterozygous Mutations in AFG3L2. THE CEREBELLUM 2019; 18:817-822. [DOI: 10.1007/s12311-019-01036-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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14
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Murru S, Hess S, Barth E, Almajan ER, Schatton D, Hermans S, Brodesser S, Langer T, Kloppenburg P, Rugarli EI. Astrocyte-specific deletion of the mitochondrial m-AAA protease reveals glial contribution to neurodegeneration. Glia 2019; 67:1526-1541. [PMID: 30989755 PMCID: PMC6618114 DOI: 10.1002/glia.23626] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 04/02/2019] [Accepted: 04/04/2019] [Indexed: 12/15/2022]
Abstract
Mitochondrial dysfunction causes neurodegeneration but whether impairment of mitochondrial homeostasis in astrocytes contributes to this pathological process remains largely unknown. The m‐AAA protease exerts quality control and regulatory functions crucial for mitochondrial homeostasis. AFG3L2, which encodes one of the subunits of the m‐AAA protease, is mutated in spinocerebellar ataxia SCA28 and in infantile syndromes characterized by spastic‐ataxia, epilepsy and premature death. Here, we investigate the role of Afg3l2 and its redundant homologue Afg3l1 in the Bergmann glia (BG), radial astrocytes of the cerebellum that have functional connections with Purkinje cells (PC) and regulate glutamate homeostasis. We show that astrocyte‐specific deletion of Afg3l2 in the mouse leads to late‐onset motor impairment and to degeneration of BG, which display aberrant morphology, altered expression of the glutamate transporter EAAT2, and a reactive inflammatory signature. The neurological and glial phenotypes are drastically exacerbated when astrocytes lack both Afg31l and Afg3l2, and therefore, are totally depleted of the m‐AAA protease. Moreover, mitochondrial stress responses and necroptotic markers are induced in the cerebellum. In both mouse models, targeted BG show a fragmented mitochondrial network and loss of mitochondrial cristae, but no signs of respiratory dysfunction. Importantly, astrocyte‐specific deficiency of Afg3l1 and Afg3l2 triggers secondary morphological degeneration and electrophysiological changes in PCs, thus demonstrating a non‐cell‐autonomous role of glia in neurodegeneration. We propose that astrocyte dysfunction amplifies both neuroinflammation and glutamate excitotoxicity in patients carrying mutations in AFG3L2, leading to a vicious circle that contributes to neuronal death.
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Affiliation(s)
- Sara Murru
- Department of Biology, Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Simon Hess
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.,Department of Biology, Institute for Zoology, Biocenter, University of Cologne, Cologne, Germany
| | - Esther Barth
- Department of Biology, Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Eva R Almajan
- Department of Biology, Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Désirée Schatton
- Department of Biology, Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Steffen Hermans
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Susanne Brodesser
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thomas Langer
- Department of Mitochondrial Proteostasis, Max-Planck-Institute for Biology of Ageing, Cologne, Germany
| | - Peter Kloppenburg
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.,Department of Biology, Institute for Zoology, Biocenter, University of Cologne, Cologne, Germany
| | - Elena I Rugarli
- Department of Biology, Institute for Genetics, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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15
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Tulli S, Del Bondio A, Baderna V, Mazza D, Codazzi F, Pierson TM, Ambrosi A, Nolte D, Goizet C, Toro C, Baets J, Deconinck T, DeJonghe P, Mandich P, Casari G, Maltecca F. Pathogenic variants in the AFG3L2 proteolytic domain cause SCA28 through haploinsufficiency and proteostatic stress-driven OMA1 activation. J Med Genet 2019; 56:499-511. [PMID: 30910913 PMCID: PMC6678042 DOI: 10.1136/jmedgenet-2018-105766] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/05/2019] [Accepted: 03/03/2019] [Indexed: 12/18/2022]
Abstract
Background Spinocerebellar ataxia type 28 (SCA28) is a dominantly inherited neurodegenerative disease caused by pathogenic variants in AFG3L2. The AFG3L2 protein is a subunit of mitochondrial m-AAA complexes involved in protein quality control. Objective of this study was to determine the molecular mechanisms of SCA28, which has eluded characterisation to date. Methods We derived SCA28 patient fibroblasts carrying different pathogenic variants in the AFG3L2 proteolytic domain (missense: the newly identified p.F664S and p.M666T, p.G671R, p.Y689H and a truncating frameshift p.L556fs) and analysed multiple aspects of mitochondrial physiology. As reference of residual m-AAA activity, we included SPAX5 patient fibroblasts with homozygous p.Y616C pathogenic variant, AFG3L2+/− HEK293 T cells by CRISPR/Cas9-genome editing and Afg3l2−/− murine fibroblasts. Results We found that SCA28 cells carrying missense changes have normal levels of assembled m-AAA complexes, while the cells with a truncating pathogenic variant had only half of this amount. We disclosed inefficient mitochondrial fusion in SCA28 cells caused by increased OPA1 processing operated by hyperactivated OMA1. Notably, we found altered mitochondrial proteostasis to be the trigger of OMA1 activation in SCA28 cells, with pharmacological attenuation of mitochondrial protein synthesis resulting in stabilised levels of OMA1 and OPA1 long forms, which rescued mitochondrial fusion efficiency. Secondary to altered mitochondrial morphology, mitochondrial calcium uptake resulted decreased in SCA28 cells. Conclusion Our data identify the earliest events in SCA28 pathogenesis and open new perspectives for therapy. By identifying similar mitochondrial phenotypes between SCA28 cells and AFG3L2+/− cells, our results support haploinsufficiency as the mechanism for the studied pathogenic variants.
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Affiliation(s)
- Susanna Tulli
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Andrea Del Bondio
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Valentina Baderna
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Davide Mazza
- Experimental Imaging Center, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Franca Codazzi
- Università Vita-Salute San Raffaele, Milan, Italy.,Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Tyler Mark Pierson
- Departments of Pediatrics and Neurology and the Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | | | - Dagmar Nolte
- Department of Medicine, Institute for Human Genetics, Justus-Liebig-University Giessen, Giessen, Germany
| | - Cyril Goizet
- Centre de Reference Neurogenetique, Service de Genetique Medicale, CHU Bordeaux, Bordeaux, France.,Laboratoire MRGM, INSERM U1211, Bordeaux, France
| | - Camilo Toro
- Undiagnosed Disease Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, Maryland, USA
| | - Jonathan Baets
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Tine Deconinck
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Peter DeJonghe
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Paola Mandich
- DINOGMI, University of Genoa and IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Giorgio Casari
- Università Vita-Salute San Raffaele, Milan, Italy.,Telethon Institute of Genetics and Medicine, Naples, Italy
| | - Francesca Maltecca
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
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16
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Richter U, Ng KY, Suomi F, Marttinen P, Turunen T, Jackson C, Suomalainen A, Vihinen H, Jokitalo E, Nyman TA, Isokallio MA, Stewart JB, Mancini C, Brusco A, Seneca S, Lombès A, Taylor RW, Battersby BJ. Mitochondrial stress response triggered by defects in protein synthesis quality control. Life Sci Alliance 2019; 2:2/1/e201800219. [PMID: 30683687 PMCID: PMC6348486 DOI: 10.26508/lsa.201800219] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 01/16/2019] [Accepted: 01/17/2019] [Indexed: 12/11/2022] Open
Abstract
Quality control defects of mitochondrial nascent chain synthesis trigger a sequential stress response characterized by OMA1 activation and ribosome decay, determining mitochondrial form and function. Mitochondria have a compartmentalized gene expression system dedicated to the synthesis of membrane proteins essential for oxidative phosphorylation. Responsive quality control mechanisms are needed to ensure that aberrant protein synthesis does not disrupt mitochondrial function. Pathogenic mutations that impede the function of the mitochondrial matrix quality control protease complex composed of AFG3L2 and paraplegin cause a multifaceted clinical syndrome. At the cell and molecular level, defects to this quality control complex are defined by impairment to mitochondrial form and function. Here, we establish the etiology of these phenotypes. We show how disruptions to the quality control of mitochondrial protein synthesis trigger a sequential stress response characterized first by OMA1 activation followed by loss of mitochondrial ribosomes and by remodelling of mitochondrial inner membrane ultrastructure. Inhibiting mitochondrial protein synthesis with chloramphenicol completely blocks this stress response. Together, our data establish a mechanism linking major cell biological phenotypes of AFG3L2 pathogenesis and show how modulation of mitochondrial protein synthesis can exert a beneficial effect on organelle homeostasis.
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Affiliation(s)
- Uwe Richter
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Kah Ying Ng
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Fumi Suomi
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Paula Marttinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Taina Turunen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Christopher Jackson
- Research Programs Unit-Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Anu Suomalainen
- Research Programs Unit-Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Tuula A Nyman
- Department of Immunology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
| | | | - James B Stewart
- Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Cecilia Mancini
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Sara Seneca
- Center for Medical Genetics/Research Center Reproduction and Genetics, Universitair Ziekenhuis Brussel, Brussels, Belgium
| | - Anne Lombès
- Faculté de médecine Cochin, Institut Cochin Institut national de la santé et de la recherche médicale U1016, Centre national de la recherche scientifique Unités Mixtes de Recherche 8104, Université Paris 5, Paris, France
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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17
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Mancini C, Hoxha E, Iommarini L, Brussino A, Richter U, Montarolo F, Cagnoli C, Parolisi R, Gondor Morosini DI, Nicolò V, Maltecca F, Muratori L, Ronchi G, Geuna S, Arnaboldi F, Donetti E, Giorgio E, Cavalieri S, Di Gregorio E, Pozzi E, Ferrero M, Riberi E, Casari G, Altruda F, Turco E, Gasparre G, Battersby BJ, Porcelli AM, Ferrero E, Brusco A, Tempia F. Mice harbouring a SCA28 patient mutation in AFG3L2 develop late-onset ataxia associated with enhanced mitochondrial proteotoxicity. Neurobiol Dis 2018; 124:14-28. [PMID: 30389403 DOI: 10.1016/j.nbd.2018.10.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 10/05/2018] [Accepted: 10/28/2018] [Indexed: 12/20/2022] Open
Abstract
Spinocerebellar ataxia 28 is an autosomal dominant neurodegenerative disorder caused by missense mutations affecting the proteolytic domain of AFG3L2, a major component of the mitochondrial m-AAA protease. However, little is known of the underlying pathogenetic mechanisms or how to treat patients with SCA28. Currently available Afg3l2 mutant mice harbour deletions that lead to severe, early-onset neurological phenotypes that do not faithfully reproduce the late-onset and slowly progressing SCA28 phenotype. Here we describe production and detailed analysis of a new knock-in murine model harbouring an Afg3l2 allele carrying the p.Met665Arg patient-derived mutation. Heterozygous mutant mice developed normally but adult mice showed signs of cerebellar ataxia detectable by beam test. Although cerebellar pathology was negative, electrophysiological analysis showed a trend towards increased spontaneous firing in Purkinje cells from heterozygous mutants with respect to wild-type controls. As homozygous mutants died perinatally with evidence of cardiac atrophy, for each genotype we generated mouse embryonic fibroblasts (MEFs) to investigate mitochondrial function. MEFs from mutant mice showed altered mitochondrial bioenergetics, with decreased basal oxygen consumption rate, ATP synthesis and mitochondrial membrane potential. Mitochondrial network formation and morphology was altered, with greatly reduced expression of fusogenic Opa1 isoforms. Mitochondrial alterations were also detected in cerebella of 18-month-old heterozygous mutants and may be a hallmark of disease. Pharmacological inhibition of de novo mitochondrial protein translation with chloramphenicol caused reversal of mitochondrial morphology in homozygous mutant MEFs, supporting the relevance of mitochondrial proteotoxicity for SCA28 pathogenesis and therapy development.
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Affiliation(s)
- Cecilia Mancini
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Eriola Hoxha
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Luisa Iommarini
- Department of Pharmacy and Biotechnologies (FABIT), University of Bologna, Bologna, Italy
| | | | - Uwe Richter
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Francesca Montarolo
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Claudia Cagnoli
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Roberta Parolisi
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Diana Iulia Gondor Morosini
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Valentina Nicolò
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
| | - Francesca Maltecca
- Università Vita-Salute San Raffaele, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Luisa Muratori
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy; Department of Clinical and Biological Sciences, University of Torino, Torino, Italy
| | - Giulia Ronchi
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy; Department of Clinical and Biological Sciences, University of Torino, Torino, Italy
| | - Stefano Geuna
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy; Department of Clinical and Biological Sciences, University of Torino, Torino, Italy
| | - Francesca Arnaboldi
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - Elena Donetti
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - Elisa Giorgio
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Simona Cavalieri
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Eleonora Di Gregorio
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Torino, Italy
| | - Elisa Pozzi
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Marta Ferrero
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Evelise Riberi
- Department of Public Health and Pediatrics, University of Torino, Torino, Italy
| | - Giorgio Casari
- Università Vita-Salute San Raffaele, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Fiorella Altruda
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Emilia Turco
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Giuseppe Gasparre
- Department Medical and Surgical Sciences, Medical Genetics, University of Bologna, Bologna, Italy
| | | | - Anna Maria Porcelli
- Department of Pharmacy and Biotechnologies (FABIT), University of Bologna, Bologna, Italy
| | - Enza Ferrero
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, Torino, Italy; Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Torino, Italy.
| | - Filippo Tempia
- Department of Neuroscience, University of Torino, Torino, Italy; Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Italy
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Neurocognitive Characterization of an SCA28 Family Caused by a Novel AFG3L2 Gene Mutation. THE CEREBELLUM 2018; 16:979-985. [PMID: 28660440 DOI: 10.1007/s12311-017-0870-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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19
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AAA Proteases: Guardians of Mitochondrial Function and Homeostasis. Cells 2018; 7:cells7100163. [PMID: 30314276 PMCID: PMC6210556 DOI: 10.3390/cells7100163] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 10/04/2018] [Accepted: 10/09/2018] [Indexed: 12/30/2022] Open
Abstract
Mitochondria are dynamic, semi-autonomous organelles that execute numerous life-sustaining tasks in eukaryotic cells. Functioning of mitochondria depends on the adequate action of versatile proteinaceous machineries. Fine-tuning of mitochondrial activity in response to cellular needs involves continuous remodeling of organellar proteome. This process not only includes modulation of various biogenetic pathways, but also the removal of superfluous proteins by adenosine triphosphate (ATP)-driven proteolytic machineries. Accordingly, all mitochondrial sub-compartments are under persistent surveillance of ATP-dependent proteases. Particularly important are highly conserved two inner mitochondrial membrane-bound metalloproteases known as m-AAA and i-AAA (ATPases associated with diverse cellular activities), whose mis-functioning may lead to impaired organellar function and consequently to development of severe diseases. Herein, we discuss the current knowledge of yeast, mammalian, and plant AAA proteases and their implications in mitochondrial function and homeostasis maintenance.
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20
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Magri S, Fracasso V, Plumari M, Alfei E, Ghezzi D, Gellera C, Rusmini P, Poletti A, Di Bella D, Elia AE, Pantaleoni C, Taroni F. Concurrent AFG3L2 and SPG7 mutations associated with syndromic parkinsonism and optic atrophy with aberrant OPA1 processing and mitochondrial network fragmentation. Hum Mutat 2018; 39:2060-2071. [PMID: 30252181 DOI: 10.1002/humu.23658] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 09/03/2018] [Accepted: 09/22/2018] [Indexed: 01/26/2023]
Abstract
Mitochondrial dynamics and quality control are crucial for neuronal survival and their perturbation is a major cause of neurodegeneration. m-AAA complex is an ATP-dependent metalloprotease located in the inner mitochondrial membrane and involved in protein quality control. Mutations in the m-AAA subunits AFG3L2 and paraplegin are associated with autosomal dominant spinocerebellar ataxia (SCA28) and autosomal recessive hereditary spastic paraplegia (SPG7), respectively. We report a novel m-AAA-associated phenotype characterized by early-onset optic atrophy with spastic ataxia and L-dopa-responsive parkinsonism. The proband carried a de novo AFG3L2 heterozygous mutation (p.R468C) along with a heterozygous maternally inherited intragenic deletion of SPG7. Functional analysis in yeast demonstrated the pathogenic role of AFG3L2 p.R468C mutation shedding light on its pathogenic mechanism. Analysis of patient's fibroblasts showed an abnormal processing pattern of OPA1, a dynamin-related protein essential for mitochondrial fusion and responsible for most cases of hereditary optic atrophy. Consistently, assessment of mitochondrial morphology revealed a severe fragmentation of the mitochondrial network, not observed in SCA28 and SPG7 patients' cells. This case suggests that coincidental mutations in both components of the mitochondrial m-AAA protease may result in a complex phenotype and reveals a crucial role for OPA1 processing in the pathogenesis of neurodegenerative disease caused by m-AAA defects.
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Affiliation(s)
- Stefania Magri
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Valentina Fracasso
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Massimo Plumari
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Enrico Alfei
- Unit of Developmental Neurology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Daniele Ghezzi
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy.,Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Università degli Studi di Milano, Milan, Italy
| | - Cinzia Gellera
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Paola Rusmini
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Angelo Poletti
- Dipartimento di Scienze Farmacologiche e Biomolecolari (DiSFeB), Centro di Eccellenza sulle Malattie Neurodegenerative, Università degli Studi di Milano, Milan, Italy
| | - Daniela Di Bella
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Antonio E Elia
- Unit of Neurology 1, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Pantaleoni
- Unit of Developmental Neurology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Franco Taroni
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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21
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Ding B, Martin DW, Rampello AJ, Glynn SE. Dissecting Substrate Specificities of the Mitochondrial AFG3L2 Protease. Biochemistry 2018; 57:4225-4235. [PMID: 29932645 DOI: 10.1021/acs.biochem.8b00565] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human AFG3L2 is a compartmental AAA+ protease that performs ATP-fueled degradation at the matrix face of the inner mitochondrial membrane. Identifying how AFG3L2 selects substrates from the diverse complement of matrix-localized proteins is essential for understanding mitochondrial protein biogenesis and quality control. Here, we create solubilized forms of AFG3L2 to examine the enzyme's substrate specificity mechanisms. We show that conserved residues within the presequence of the mitochondrial ribosomal protein, MrpL32, target the subunit to the protease for processing into a mature form. Moreover, these residues can act as a degron, delivering diverse model proteins to AFG3L2 for degradation. By determining the sequence of degradation products from multiple substrates using mass spectrometry, we construct a peptidase specificity profile that displays constrained product lengths and is dominated by the identity of the residue at the P1' position, with a strong preference for hydrophobic and small polar residues. This specificity profile is validated by examining the cleavage of both fluorogenic reporter peptides and full polypeptide substrates bearing different P1' residues. Together, these results demonstrate that AFG3L2 contains multiple modes of specificity, discriminating between potential substrates by recognizing accessible degron sequences and performing peptide bond cleavage at preferred patterns of residues within the compartmental chamber.
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22
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Sun M, Johnson AK, Nelakuditi V, Guidugli L, Fischer D, Arndt K, Ma L, Sandford E, Shakkottai V, Boycott K, Chardon JW, Li Z, Del Gaudio D, Burmeister M, Gomez CM, Waggoner DJ, Das S. Targeted exome analysis identifies the genetic basis of disease in over 50% of patients with a wide range of ataxia-related phenotypes. Genet Med 2018; 21:195-206. [PMID: 29915382 DOI: 10.1038/s41436-018-0007-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 03/20/2018] [Indexed: 01/26/2023] Open
Abstract
PURPOSE To examine the impact of a targeted exome approach for the molecular diagnosis of patients nationwide with a wide range of ataxia-related phenotypes. METHODS One hundred and seventy patients with ataxia of unknown etiology referred from clinics throughout the United States and Canada were studied using a targeted exome approach. Patients ranged in age from 2 to 88 years. Analysis was focused on 441 curated genes associated with ataxia and ataxia-like conditions. RESULTS Pathogenic and suspected diagnostic variants were identified in 88 of the 170 patients, providing a positive molecular diagnostic rate of 52%. Forty-six different genes were implicated, with the six most commonly mutated genes being SPG7, SYNE1, ADCK3, CACNA1A, ATP1A3, and SPTBN2, which accounted for >40% of the positive cases. In many cases a diagnosis was provided for conditions that were not suspected and resulted in the broadening of the clinical spectrum of several conditions. CONCLUSION Exome sequencing with targeted analysis provides a high-yield approach for the genetic diagnosis of ataxia-related conditions. This is the largest targeted exome study performed to date in patients with ataxia and ataxia-like conditions and represents patients with a wide range of ataxia phenotypes typically encountered in neurology and genetics clinics.
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Affiliation(s)
- Miao Sun
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Amy Knight Johnson
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | | | - Lucia Guidugli
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - David Fischer
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Kelly Arndt
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Lan Ma
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Erin Sandford
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Vikram Shakkottai
- Department of Neurology, Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Kym Boycott
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Jodi Warman Chardon
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada.,The Ottawa Hospital/OHRI, Ottawa, ON, Canada
| | - Zejuan Li
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Daniela Del Gaudio
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Margit Burmeister
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | | | - Darrel J Waggoner
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Soma Das
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA.
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23
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Movement disorders in mitochondrial disease. J Neurol 2018; 265:1230-1240. [PMID: 29307008 DOI: 10.1007/s00415-017-8722-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 12/21/2017] [Accepted: 12/22/2017] [Indexed: 12/14/2022]
Abstract
Mitochondrial disease presents with a wide spectrum of clinical manifestations that may appear at any age and cause multisystem dysfunction. A broad spectrum of movement disorders can manifest in mitochondrial diseases including ataxia, Parkinsonism, myoclonus, dystonia, choreoathetosis, spasticity, tremor, tic disorders and restless legs syndrome. There is marked heterogeneity of movement disorder phenotypes, even in patients with the same genetic mutation. Moreover, the advent of new technologies, such as next-generation sequencing, is likely to identify novel causative genes, expand the phenotype of known disease genes and improve the genetic diagnosis in these patients. Identification of the underlying genetic basis of the movement disorder is also a crucial step to allow for targeted therapies to be implemented as well as provide the basis for a better understanding of the molecular pathophysiology of the disease process. The aim of this review is to discuss the spectrum of movement disorders associated with mitochondrial disease.
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24
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25
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Nibbeling EAR, Duarri A, Verschuuren-Bemelmans CC, Fokkens MR, Karjalainen JM, Smeets CJLM, de Boer-Bergsma JJ, van der Vries G, Dooijes D, Bampi GB, van Diemen C, Brunt E, Ippel E, Kremer B, Vlak M, Adir N, Wijmenga C, van de Warrenburg BPC, Franke L, Sinke RJ, Verbeek DS. Exome sequencing and network analysis identifies shared mechanisms underlying spinocerebellar ataxia. Brain 2017; 140:2860-2878. [PMID: 29053796 DOI: 10.1093/brain/awx251] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 08/05/2017] [Indexed: 12/17/2022] Open
Abstract
The autosomal dominant cerebellar ataxias, referred to as spinocerebellar ataxias in genetic nomenclature, are a rare group of progressive neurodegenerative disorders characterized by loss of balance and coordination. Despite the identification of numerous disease genes, a substantial number of cases still remain without a genetic diagnosis. Here, we report five novel spinocerebellar ataxia genes, FAT2, PLD3, KIF26B, EP300, and FAT1, identified through a combination of exome sequencing in genetically undiagnosed families and targeted resequencing of exome candidates in a cohort of singletons. We validated almost all genes genetically, assessed damaging effects of the gene variants in cell models and further consolidated a role for several of these genes in the aetiology of spinocerebellar ataxia through network analysis. Our work links spinocerebellar ataxia to alterations in synaptic transmission and transcription regulation, and identifies these as the main shared mechanisms underlying the genetically diverse spinocerebellar ataxia types.
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Affiliation(s)
- Esther A R Nibbeling
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Anna Duarri
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | - Michiel R Fokkens
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Juha M Karjalainen
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Cleo J L M Smeets
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jelkje J de Boer-Bergsma
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Gerben van der Vries
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Dennis Dooijes
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Giovana B Bampi
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Cleo van Diemen
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ewout Brunt
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Elly Ippel
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Berry Kremer
- Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Monique Vlak
- Department of Neurology, Medical Center Haaglanden and Bronovo-Nebo, Den Hague, The Netherlands
| | - Noam Adir
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Technion City, Israel
| | - Cisca Wijmenga
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | - Lude Franke
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Richard J Sinke
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Dineke S Verbeek
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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26
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SCA28: Novel Mutation in the AFG3L2 Proteolytic Domain Causes a Mild Cerebellar Syndrome with Selective Type-1 Muscle Fiber Atrophy. THE CEREBELLUM 2017; 16:62-67. [PMID: 26868664 DOI: 10.1007/s12311-016-0765-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The spinocerebellar ataxias (SCA) are a group of rare inherited neurodegenerative diseases characterized by slowly progressive cerebellar ataxia, resulting in unsteady gait, clumsiness, and dysarthria. The disorders are predominantly inherited in an autosomal dominant manner. Mutations in the gene AFG3L2 that encodes a subunit of the mitochondrial m-AAA protease have previously been shown to cause spinocerebellar ataxia type 28 (SCA28). Here, we present the clinical phenotypes of three patients from a family with autosomal dominant cerebellar ataxia and show by molecular genetics and in silico modelling that this is caused by a novel missense mutation in the AFG3L2 gene. Furthermore, we show, for the first time, fluorodeoxyglucose-positron emission tomography (FDG-PET) scans of the brain and selective type I fiber atrophy of skeletal muscle of SCA28 patients indicating non-nervous-system involvement in SCA28 as well.
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27
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Colavito D, Maritan V, Suppiej A, Del Giudice E, Mazzarolo M, Miotto S, Farina S, Dalle Carbonare M, Piermarocchi S, Leon A. Non-syndromic isolated dominant optic atrophy caused by the p.R468C mutation in the AFG3 like matrix AAA peptidase subunit 2 gene. Biomed Rep 2017; 7:451-454. [PMID: 29181157 DOI: 10.3892/br.2017.987] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 09/14/2017] [Indexed: 12/25/2022] Open
Abstract
Autosomal dominant optic atrophy (DOA) is the most frequent form of hereditary optic atrophy, a disease presenting with considerable inter- and intra-familial clinical variability. Although a number of mutations in different genes are now known to cause DOA, many cases remain undiagnosed. In an attempt to identify the underlying genetic defect, whole exome sequencing was performed in a 19-year-old male that had been affected by isolated DOA since childhood. The exome sequencing revealed a pathogenic mutation (p.R468C, c.1402C>T) in the AFG3 like matrix AAA peptidase subunit 2 (AFG3L2) gene, a gene known to be associated with spinocerebellar ataxia. The patient did not show any signs other than DOA. Thus, the result demonstrates the possibility that mutations in the AFG3L2 gene may be a cause of isolated autosomal DOA.
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Affiliation(s)
| | - Veronica Maritan
- Paediatric Low Vision Center, Women's and Children's Health Department, University of Padua, Italy
| | - Agnese Suppiej
- Child Neurology and Clinical Neurophysiology Unit, Pediatric University Hospital of Padua, I-35100 Padua, Italy
| | | | - Monica Mazzarolo
- Paediatric Low Vision Center, Women's and Children's Health Department, University of Padua, Italy
| | - Stefania Miotto
- ULSS 6 Euganea, phthalmology Unit, Camposampiero Hospital, I-35012 Padua, Italy
| | - Sofia Farina
- Research and Innovation Srl, I-35127 Padua, Italy
| | | | | | - Alberta Leon
- Research and Innovation Srl, I-35127 Padua, Italy
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28
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Glynn SE. Multifunctional Mitochondrial AAA Proteases. Front Mol Biosci 2017; 4:34. [PMID: 28589125 PMCID: PMC5438985 DOI: 10.3389/fmolb.2017.00034] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/08/2017] [Indexed: 11/28/2022] Open
Abstract
Mitochondria perform numerous functions necessary for the survival of eukaryotic cells. These activities are coordinated by a diverse complement of proteins encoded in both the nuclear and mitochondrial genomes that must be properly organized and maintained. Misregulation of mitochondrial proteostasis impairs organellar function and can result in the development of severe human diseases. ATP-driven AAA+ proteins play crucial roles in preserving mitochondrial activity by removing and remodeling protein molecules in accordance with the needs of the cell. Two mitochondrial AAA proteases, i-AAA and m-AAA, are anchored to either face of the mitochondrial inner membrane, where they engage and process an array of substrates to impact protein biogenesis, quality control, and the regulation of key metabolic pathways. The functionality of these proteases is extended through multiple substrate-dependent modes of action, including complete degradation, partial processing, or dislocation from the membrane without proteolysis. This review discusses recent advances made toward elucidating the mechanisms of substrate recognition, handling, and degradation that allow these versatile proteases to control diverse activities in this multifunctional organelle.
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Affiliation(s)
- Steven E Glynn
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony Brook, NY, United States
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29
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Oláhová M, Thompson K, Hardy SA, Barbosa IA, Besse A, Anagnostou ME, White K, Davey T, Simpson MA, Champion M, Enns G, Schelley S, Lightowlers RN, Chrzanowska-Lightowlers ZMA, McFarland R, Deshpande C, Bonnen PE, Taylor RW. Pathogenic variants in HTRA2 cause an early-onset mitochondrial syndrome associated with 3-methylglutaconic aciduria. J Inherit Metab Dis 2017; 40:121-130. [PMID: 27696117 PMCID: PMC5203855 DOI: 10.1007/s10545-016-9977-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 09/02/2016] [Accepted: 09/06/2016] [Indexed: 01/13/2023]
Abstract
Mitochondrial diseases collectively represent one of the most heterogeneous group of metabolic disorders. Symptoms can manifest at any age, presenting with isolated or multiple-organ involvement. Advances in next-generation sequencing strategies have greatly enhanced the diagnosis of patients with mitochondrial disease, particularly where a mitochondrial aetiology is strongly suspected yet OXPHOS activities in biopsied tissue samples appear normal. We used whole exome sequencing (WES) to identify the molecular basis of an early-onset mitochondrial syndrome-pathogenic biallelic variants in the HTRA2 gene, encoding a mitochondria-localised serine protease-in five subjects from two unrelated families characterised by seizures, neutropenia, hypotonia and cardio-respiratory problems. A unifying feature in all affected children was 3-methylglutaconic aciduria (3-MGA-uria), a common biochemical marker observed in some patients with mitochondrial dysfunction. Although functional studies of HTRA2 subjects' fibroblasts and skeletal muscle homogenates showed severely decreased levels of mutant HTRA2 protein, the structural subunits and complexes of the mitochondrial respiratory chain appeared normal. We did detect a profound defect in OPA1 processing in HTRA2-deficient fibroblasts, suggesting a role for HTRA2 in the regulation of mitochondrial dynamics and OPA1 proteolysis. In addition, investigated subject fibroblasts were more susceptible to apoptotic insults. Our data support recent studies that described important functions for HTRA2 in programmed cell death and confirm that patients with genetically-unresolved 3-MGA-uria should be screened by WES with pathogenic variants in the HTRA2 gene prioritised for further analysis.
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Affiliation(s)
- Monika Oláhová
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Kyle Thompson
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Steven A Hardy
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Inês A Barbosa
- Division of Genetics and Molecular Medicine, King's College London School of Medicine, London, UK
| | - Arnaud Besse
- Dept of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Maria-Eleni Anagnostou
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Kathryn White
- Electron Microscopy Research Services, Newcastle University, Newcastle upon Tyne, UK
| | - Tracey Davey
- Electron Microscopy Research Services, Newcastle University, Newcastle upon Tyne, UK
| | - Michael A Simpson
- Division of Genetics and Molecular Medicine, King's College London School of Medicine, London, UK
| | - Michael Champion
- Department of Inherited Metabolic Disease, Guy's and St Thomas' NHS Foundation Trusts, Evelina London Children's Hospital, London, UK
| | - Greg Enns
- Lucile Packard Children's Hospital Stanford and Stanford University Medical Center, Palo Alto, CA, USA
| | - Susan Schelley
- Lucile Packard Children's Hospital Stanford and Stanford University Medical Center, Palo Alto, CA, USA
| | - Robert N Lightowlers
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Zofia M A Chrzanowska-Lightowlers
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Charu Deshpande
- Clinical Genetics Unit, Guys and St Thomas' NHS Foundation Trust, London, UK
| | - Penelope E Bonnen
- Dept of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
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Levytskyy RM, Germany EM, Khalimonchuk O. Mitochondrial Quality Control Proteases in Neuronal Welfare. J Neuroimmune Pharmacol 2016; 11:629-644. [PMID: 27137937 PMCID: PMC5093085 DOI: 10.1007/s11481-016-9683-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/27/2016] [Indexed: 01/01/2023]
Abstract
The functional integrity of mitochondria is a critical determinant of neuronal health and compromised mitochondrial function is a commonly recognized factor that underlies a plethora of neurological and neurodegenerative diseases. Metabolic demands of neural cells require high bioenergetic outputs that are often associated with enhanced production of reactive oxygen species. Unopposed accumulation of these respiratory byproducts over time leads to oxidative damage and imbalanced protein homeostasis within mitochondrial subcompartments, which in turn may result in cellular demise. The post-mitotic nature of neurons and their vulnerability to these stress factors necessitate strict protein homeostatic control to prevent such scenarios. A series of evolutionarily conserved proteases is one of the central elements of mitochondrial quality control. These versatile proteolytic enzymes conduct a multitude of activities to preserve normal mitochondrial function during organelle biogenesis, metabolic remodeling and stress. In this review we discuss neuroprotective aspects of mitochondrial quality control proteases and neuropathological manifestations arising from defective proteolysis within the mitochondrion.
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Affiliation(s)
- Roman M Levytskyy
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Edward M Germany
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Oleh Khalimonchuk
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
- Nebraska Redox Biology Center, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
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31
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Sun YM, Lu C, Wu ZY. Spinocerebellar ataxia: relationship between phenotype and genotype - a review. Clin Genet 2016; 90:305-14. [PMID: 27220866 DOI: 10.1111/cge.12808] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 05/16/2016] [Accepted: 05/16/2016] [Indexed: 12/12/2022]
Abstract
Spinocerebellar ataxia (SCA) comprises a large group of heterogeneous neurodegenerative disorders inherited in an autosomal dominant fashion. It is characterized by progressive cerebellar ataxia with oculomotor dysfunction, dysarthria, pyramidal signs, extrapyramidal signs, pigmentary retinopathy, peripheral neuropathy, cognitive impairment and other symptoms. It is classified according to the clinical manifestations or genetic nosology. To date, 40 SCAs have been characterized, and include SCA1-40. The pathogenic genes of 28 SCAs were identified. In recent years, with the widespread clinical use of next-generation sequencing, the genes underlying SCAs, and the mutants as well as the affected phenotypes were identified. These advances elucidated the phenotype-genotype relationship in SCAs. We reviewed the recent clinical advances, genetic features and phenotype-genotype correlations involving each SCA and its differentiation. The heterogeneity of the disease and the genetic diagnosis might be attributed to the regional distribution and clinical characteristics. Therefore, recognition of the phenotype-genotype relationship facilitates genetic testing, prognosis and monitoring of symptoms.
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Affiliation(s)
- Y-M Sun
- Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - C Lu
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, the Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, China.,Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Z-Y Wu
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, the Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, China. .,Joint Institute for Genetics and Genome Medicine between Zhejiang University and University of Toronto, Zhejiang University, Hangzhou, China.
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Zühlke C, Mikat B, Timmann D, Wieczorek D, Gillessen-Kaesbach G, Bürk K. Spinocerebellar ataxia 28: a novel AFG3L2 mutation in a German family with young onset, slow progression and saccadic slowing. CEREBELLUM & ATAXIAS 2015; 2:19. [PMID: 26677414 PMCID: PMC4681123 DOI: 10.1186/s40673-015-0038-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 12/03/2015] [Indexed: 12/20/2022]
Abstract
Background Spinocerebellar ataxia type 28 (SCA28) is related to mutations of the ATPase family gene 3-like 2 gene (AFG3L2). To date, 13 private missense mutations have been identified in families of French, Italian, and German ancestry, but overall, the disorder seems to be rare in Europe. Here, we report a kindred of German ancestry with four affected family members presenting with slowly progressive ataxia, mild pyramidal tract signs and slow saccades. Methods After excluding repeat expansions in the genes for SCA1-3, 6-8, 10, 12, and 17, Sanger sequencing of the coding regions of TTBK2 (SCA11), KCNC3 (SCA13), PRKCG (SCA14), FGF14 (SCA27) and AFG3L2 (SCA28) was performed. The 17 coding exons of AFG3L2 with flanking intronic sequences were amplified by PCR and sequenced on both strands. Results Sequencing detected a novel potential missense mutation (p.Y689N) in the C-terminal proteolytic domain, the mutational hotspot of AFG3L2. The online programme “PolyPhen-2” classifies this amino acid exchange as probably damaging (score 0.990). Similarly to most of the published SCA28 mutations, the novel mutation is located within exon 16. Mutations in exon 16 alter the proteolytic activity of the protease AFG3L2 that is highly expressed in Purkinje cells. Conclusions Genetic testing should be considered in dominant ataxia with pyramidal tract signs and saccadic slowing.
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Affiliation(s)
- Christine Zühlke
- Institute of Human Genetics, University of Lübeck, Lübeck, Germany
| | - Barbara Mikat
- Institute of Human Genetics, University of Duisburg-Essen, Essen, Germany
| | - Dagmar Timmann
- Department of Neurology, University of Essen, Essen, Germany
| | - Dagmar Wieczorek
- Institute of Human Genetics, University of Duisburg-Essen, Essen, Germany
| | | | - Katrin Bürk
- Department of Neurology, Philipps University of Marburg, Baldinger straße, 53043 Marburg, Germany.,Paracelsus-Elena Klinik, Kassel, Germany
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Charif M, Roubertie A, Salime S, Mamouni S, Goizet C, Hamel CP, Lenaers G. A novel mutation of AFG3L2 might cause dominant optic atrophy in patients with mild intellectual disability. Front Genet 2015; 6:311. [PMID: 26539208 PMCID: PMC4609881 DOI: 10.3389/fgene.2015.00311] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 09/28/2015] [Indexed: 11/23/2022] Open
Abstract
Dominant optic neuropathies causing fiber loss in the optic nerve are among the most frequent inherited mitochondrial diseases. In most genetically resolved cases, the disease is associated to a mutation in OPA1, which encodes an inner mitochondrial dynamin involved in network fusion, cristae structure and mitochondrial genome maintenance. OPA1 cleavage is regulated by two m-AAA proteases, SPG7 and AFG3L2, which are, respectively involved in Spastic Paraplegia 7 and Spino-Cerebellar Ataxia 28. Here, we identified a novel mutation c.1402C>T in AFG3L2, modifying the arginine 468 in cysteine in an evolutionary highly conserved arginine-finger motif, in a family with optic atrophy and mild intellectual disability. Ophthalmic examinations disclosed a loss of retinal nerve fibers on the temporal and nasal sides of the optic disk and a red–green dyschromatopsia. Thus, our results suggest that neuro-ophthalmological symptom as optic atrophy might be associated with AFG3L2 mutations, and should prompt the screening of this gene in patients with isolated and syndromic inherited optic neuropathies.
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Affiliation(s)
- Majida Charif
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier Montpellier, France ; PREMMi, CNRS UMR 6214 - INSERM U1083, Département de Biochimie et Génétique, Université d'Angers, CHU d'Angers Angers, France
| | - Agathe Roubertie
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier Montpellier, France ; CHRU Montpellier, Service de Neuro-pédiatrie, Hôpital Gui de Chauliac Montpellier, France
| | - Sara Salime
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier Montpellier, France
| | - Sonia Mamouni
- CHRU Montpellier, Centre de Référence pour les Maladies Sensorielles Génétiques, Hôpital Gui de Chauliac Montpellier, France
| | - Cyril Goizet
- CHU Bordeaux, Service de Génétique Médicale and Université de Bordeaux, Laboratoire Maladies Rares, Génétique et Métabolisme (MRGM) Bordeaux, France
| | - Christian P Hamel
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier Montpellier, France ; CHRU Montpellier, Centre de Référence pour les Maladies Sensorielles Génétiques, Hôpital Gui de Chauliac Montpellier, France
| | - Guy Lenaers
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier Montpellier, France ; PREMMi, CNRS UMR 6214 - INSERM U1083, Département de Biochimie et Génétique, Université d'Angers, CHU d'Angers Angers, France
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34
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Abstract
While the onset of a dominantly inherited ataxia is typically taken to be the onset of gait ataxia, a wide range of other symptoms related to central and/or peripheral nervous system impairment, or even to non-neurological involvement, can be the presenting feature. Knowledge of these is fairly robust for the commonest spinocerebellar ataxias (SCAs 1, 2, 3 and 6) and for those where a striking non-ataxic presentation is the norm (SCAs 7 and 12), but the literature is potentially misleading in the rarer dominant ataxias. This review summarises what is currently known of these non-ataxic presentations and outlines and explains the difficulties associated with determining non-ataxic presentations of dominant ataxias. The relevant literature was surveyed, including systematic reviews (where available) and case reports. Non-ataxic presentations of dominant ataxias are classified by symptom.
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Affiliation(s)
- Elsdon Storey
- Department of Medicine (Neuroscience), Monash University, Alfred Hospital Campus, Commercial Road, Melbourne, VIC, 3004, Australia. .,Department of Neuroscience, Alfred Hospital, Commercial Road, Melbourne, VIC, 3004, Australia.
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Mancini C, Orsi L, Guo Y, Li J, Chen Y, Wang F, Tian L, Liu X, Zhang J, Jiang H, Nmezi BS, Tatsuta T, Giorgio E, Di Gregorio E, Cavalieri S, Pozzi E, Mortara P, Caglio MM, Balducci A, Pinessi L, Langer T, Padiath QS, Hakonarson H, Zhang X, Brusco A. An atypical form of AOA2 with myoclonus associated with mutations in SETX and AFG3L2. BMC MEDICAL GENETICS 2015; 16:16. [PMID: 25927548 PMCID: PMC4422141 DOI: 10.1186/s12881-015-0159-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/26/2015] [Indexed: 11/10/2022]
Abstract
BACKGROUND Hereditary ataxias are a heterogeneous group of neurodegenerative disorders, where exome sequencing may become an important diagnostic tool to solve clinically or genetically complex cases. METHODS We describe an Italian family in which three sisters were affected by ataxia with postural/intentional myoclonus and involuntary movements at onset, which persisted during the disease. Oculomotor apraxia was absent. Clinical and genetic data did not allow us to exclude autosomal dominant or recessive inheritance and suggest a disease gene. RESULTS Exome sequencing identified a homozygous c.6292C > T (p.Arg2098*) mutation in SETX and a heterozygous c.346G > A (p.Gly116Arg) mutation in AFG3L2 shared by all three affected individuals. A fourth sister (II.7) had subclinical myoclonic jerks at proximal upper limbs and perioral district, confirmed by electrophysiology, and carried the p.Gly116Arg change. Three siblings were healthy. Pathogenicity prediction and a yeast-functional assay suggested p.Gly116Arg impaired m-AAA (ATPases associated with various cellular activities) complex function. CONCLUSIONS Exome sequencing is a powerful tool in identifying disease genes. We identified an atypical form of Ataxia with Oculoapraxia type 2 (AOA2) with myoclonus at onset associated with the c.6292C > T (p.Arg2098*) homozygous mutation. Because the same genotype was described in six cases from a Tunisian family with a typical AOA2 without myoclonus, we speculate this latter feature is associated with a second mutated gene, namely AFG3L2 (p.Gly116Arg variant). We suggest that variant phenotypes may be due to the combined effect of different mutated genes associated to ataxia or related disorders, that will become more apparent as the costs of exome sequencing progressively will reduce, amplifying its diagnostics use, and meanwhile proposing significant challenges in the interpretation of the data.
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Affiliation(s)
- Cecilia Mancini
- Department of Medical Sciences, University of Torino, via Santena 19, 10126, Torino, Italy.
| | - Laura Orsi
- Struttura Complessa Neurologia I, Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy.
| | - Yiran Guo
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
| | | | | | - Fengxiang Wang
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
| | - Lifeng Tian
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA.
| | | | | | - Hui Jiang
- BGI-Shenzhen, Shenzhen, 510803, China. .,Shenzhen Key Laboratory of Genomics, Shenzhen, 518083, China. .,The Guangdong Enterprise Key Laboratory of Human Disease Genomics, BGI-Shenzhen, Shenzhen, 510803, China.
| | - Bruce Shike Nmezi
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
| | - Takashi Tatsuta
- Institute for Genetics, Center for Molecular Medicine (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, 50931, Germany.
| | - Elisa Giorgio
- Department of Medical Sciences, University of Torino, via Santena 19, 10126, Torino, Italy.
| | - Eleonora Di Gregorio
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy.
| | - Simona Cavalieri
- Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy.
| | - Elisa Pozzi
- Department of Medical Sciences, University of Torino, via Santena 19, 10126, Torino, Italy.
| | - Paolo Mortara
- Struttura Complessa Neurologia I, Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy. .,Department of Neuroscience, University of Torino, Torino, 10126, Italy.
| | - Maria Marcella Caglio
- Department of Neuroscience, University of Torino, Torino, 10126, Italy. .,Division of Neurology III, Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy.
| | - Alessandro Balducci
- Department of Neuroscience, University of Torino, Torino, 10126, Italy. .,Division of Neurology III, Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy.
| | - Lorenzo Pinessi
- Struttura Complessa Neurologia I, Department of Neuroscience and Mental Health, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy. .,Department of Neuroscience, University of Torino, Torino, 10126, Italy.
| | - Thomas Langer
- Institute for Genetics, Center for Molecular Medicine (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, 50931, Germany. .,Max-Planck-Institute for Biology of Aging, Cologne, 50931, Germany.
| | - Quasar S Padiath
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, 15261, USA.
| | - Hakon Hakonarson
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA. .,Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA. .,Department of Pediatrics, The Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Xiuqing Zhang
- BGI-Shenzhen, Shenzhen, 510803, China. .,Shenzhen Key Laboratory of Genomics, Shenzhen, 518083, China. .,The Guangdong Enterprise Key Laboratory of Human Disease Genomics, BGI-Shenzhen, Shenzhen, 510803, China.
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, via Santena 19, 10126, Torino, Italy. .,Medical Genetics Unit, Città della Salute e della Scienza University Hospital, Torino, 10126, Italy.
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Duarri A, Nibbeling EAR, Fokkens MR, Meijer M, Boerrigter M, Verschuuren-Bemelmans CC, Kremer BPH, van de Warrenburg BP, Dooijes D, Boddeke E, Sinke RJ, Verbeek DS. Functional analysis helps to define KCNC3 mutational spectrum in Dutch ataxia cases. PLoS One 2015; 10:e0116599. [PMID: 25756792 PMCID: PMC4355074 DOI: 10.1371/journal.pone.0116599] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 12/12/2014] [Indexed: 12/03/2022] Open
Abstract
Spinocerebellar ataxia type 13 (SCA13) is an autosomal dominantly inherited neurodegenerative disorder of the cerebellum caused by mutations in the voltage gated potassium channel KCNC3. To identify novel pathogenic SCA13 mutations in KCNC3 and to gain insights into the disease prevalence in the Netherlands, we sequenced the entire coding region of KCNC3 in 848 Dutch cerebellar ataxia patients with familial or sporadic origin. We evaluated the pathogenicity of the identified variants by co-segregation analysis and in silico prediction followed by biochemical and electrophysiological studies. We identified 19 variants in KCNC3 including 2 non-coding, 11 missense and 6 synonymous variants. Two missense variants did not co-segregate with the disease and were excluded as potentially disease-causing mutations. We also identified the previously reported p.R420H and p.R423H mutations in our cohort. Of the remaining 7 missense variants, functional analysis revealed that 2 missense variants shifted Kv3.3 channel activation to more negative voltages. These variations were associated with early disease onset and mild intellectual disability. Additionally, one other missense variant shifted channel activation to more positive voltages and was associated with spastic ataxic gait. Whereas, the remaining missense variants did not change any of the channel characteristics. Of these three functional variants, only one variant was in silico predicted to be damaging and segregated with disease. The other two variants were in silico predicted to be benign and co-segregation analysis was not optimal or could only be partially confirmed. Therefore, we conclude that we have identified at least one novel pathogenic mutation in KCNC3 that cause SCA13 and two additionally potential SCA13 mutations. This leads to an estimate of SCA13 prevalence in the Netherlands to be between 0.6% and 1.3%.
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Affiliation(s)
- Anna Duarri
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Esther A. R. Nibbeling
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Michiel R. Fokkens
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Michel Meijer
- Department of Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Melissa Boerrigter
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Berry P. H. Kremer
- Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | | | - Dennis Dooijes
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Erik Boddeke
- Department of Medical Physiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Richard J. Sinke
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Dineke S. Verbeek
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- * E-mail:
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Baker MJ, Palmer CS, Stojanovski D. Mitochondrial protein quality control in health and disease. Br J Pharmacol 2014; 171:1870-89. [PMID: 24117041 DOI: 10.1111/bph.12430] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 08/28/2013] [Accepted: 09/01/2013] [Indexed: 12/13/2022] Open
Abstract
Progressive mitochondrial dysfunction is linked with the onset of many age-related pathologies and neurological disorders. Mitochondrial damage can come in many forms and be induced by a variety of cellular insults. To preserve organelle function during biogenesis or times of stress, multiple surveillance systems work to ensure the persistence of a functional mitochondrial network. This review provides an overview of these processes, which collectively contribute to the maintenance of a healthy mitochondrial population, which is critical for cell physiology and survival.
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Affiliation(s)
- Michael J Baker
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia; ARC Centre of Excellence for Coherent X-ray Science, Melbourne, VIC, Australia
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Maltecca F, Baseggio E, Consolato F, Mazza D, Podini P, Young SM, Drago I, Bahr BA, Puliti A, Codazzi F, Quattrini A, Casari G. Purkinje neuron Ca2+ influx reduction rescues ataxia in SCA28 model. J Clin Invest 2014; 125:263-74. [PMID: 25485680 DOI: 10.1172/jci74770] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 11/06/2014] [Indexed: 12/11/2022] Open
Abstract
Spinocerebellar ataxia type 28 (SCA28) is a neurodegenerative disease caused by mutations of the mitochondrial protease AFG3L2. The SCA28 mouse model, which is haploinsufficient for Afg3l2, exhibits a progressive decline in motor function and displays dark degeneration of Purkinje cells (PC-DCD) of mitochondrial origin. Here, we determined that mitochondria in cultured Afg3l2-deficient PCs ineffectively buffer evoked Ca²⁺ peaks, resulting in enhanced cytoplasmic Ca²⁺ concentrations, which subsequently triggers PC-DCD. This Ca²⁺-handling defect is the result of negative synergism between mitochondrial depolarization and altered organelle trafficking to PC dendrites in Afg3l2-mutant cells. In SCA28 mice, partial genetic silencing of the metabotropic glutamate receptor mGluR1 decreased Ca²⁺ influx in PCs and reversed the ataxic phenotype. Moreover, administration of the β-lactam antibiotic ceftriaxone, which promotes synaptic glutamate clearance, thereby reducing Ca²⁺ influx, improved ataxia-associated phenotypes in SCA28 mice when given either prior to or after symptom onset. Together, the results of this study indicate that ineffective mitochondrial Ca²⁺ handling in PCs underlies SCA28 pathogenesis and suggest that strategies that lower glutamate stimulation of PCs should be further explored as a potential treatment for SCA28 patients.
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Myers KA, Warman Chardon J, Huang L, Boycott KM. Deletion ofAFG3L2associated with spinocerebellar ataxia type 28 in the context of multiple genomic anomalies. Am J Med Genet A 2014; 164A:3209-12. [DOI: 10.1002/ajmg.a.36771] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 08/20/2014] [Indexed: 11/10/2022]
Affiliation(s)
- Kenneth A. Myers
- Division of Neurology; Department of Pediatrics; Alberta Children's Hospital; University of Calgary; Calgary Alberta Canada
| | - Jodi Warman Chardon
- Department of Genetics; Children's Hospital of Eastern Ontario; University of Ottawa; Ottawa Ontario Canada
| | - Lijia Huang
- Department of Genetics; Children's Hospital of Eastern Ontario; University of Ottawa; Ottawa Ontario Canada
| | - Kym M. Boycott
- Department of Genetics; Children's Hospital of Eastern Ontario; University of Ottawa; Ottawa Ontario Canada
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40
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Sandford E, Burmeister M. Genes and genetic testing in hereditary ataxias. Genes (Basel) 2014; 5:586-603. [PMID: 25055202 PMCID: PMC4198919 DOI: 10.3390/genes5030586] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/25/2014] [Accepted: 07/01/2014] [Indexed: 12/19/2022] Open
Abstract
Ataxia is a neurological cerebellar disorder characterized by loss of coordination during muscle movements affecting walking, vision, and speech. Genetic ataxias are very heterogeneous, with causative variants reported in over 50 genes, which can be inherited in classical dominant, recessive, X-linked, or mitochondrial fashion. A common mechanism of dominant ataxias is repeat expansions, where increasing lengths of repeated DNA sequences result in non-functional proteins that accumulate in the body causing disease. Greater understanding of all ataxia genes has helped identify several different pathways, such as DNA repair, ubiquitination, and ion transport, which can be used to help further identify new genes and potential treatments. Testing for the most common mutations in these genes is now clinically routine to help with prognosis and treatment decisions, but next generation sequencing will revolutionize how genetic testing will be done. Despite the large number of known ataxia causing genes, however, many individuals with ataxia are unable to obtain a genetic diagnosis, suggesting that more genes need to be discovered. Utilization of next generation sequencing technologies, expression studies, and increased knowledge of ataxia pathways will aid in the identification of new ataxia genes.
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Affiliation(s)
- Erin Sandford
- Molecular & Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Margit Burmeister
- Molecular & Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, USA.
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Chaussenot A, Paquis-Flucklinger V. An overview of neurological and neuromuscular signs in mitochondrial diseases. Rev Neurol (Paris) 2014; 170:323-38. [DOI: 10.1016/j.neurol.2014.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 03/24/2014] [Indexed: 01/10/2023]
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Pfeffer G, Gorman GS, Griffin H, Kurzawa-Akanbi M, Blakely EL, Wilson I, Sitarz K, Moore D, Murphy JL, Alston CL, Pyle A, Coxhead J, Payne B, Gorrie GH, Longman C, Hadjivassiliou M, McConville J, Dick D, Imam I, Hilton D, Norwood F, Baker MR, Jaiser SR, Yu-Wai-Man P, Farrell M, McCarthy A, Lynch T, McFarland R, Schaefer AM, Turnbull DM, Horvath R, Taylor RW, Chinnery PF. Mutations in the SPG7 gene cause chronic progressive external ophthalmoplegia through disordered mitochondrial DNA maintenance. Brain 2014; 137:1323-36. [PMID: 24727571 PMCID: PMC3999722 DOI: 10.1093/brain/awu060] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/12/2014] [Accepted: 01/30/2014] [Indexed: 12/12/2022] Open
Abstract
Despite being a canonical presenting feature of mitochondrial disease, the genetic basis of progressive external ophthalmoplegia remains unknown in a large proportion of patients. Here we show that mutations in SPG7 are a novel cause of progressive external ophthalmoplegia associated with multiple mitochondrial DNA deletions. After excluding known causes, whole exome sequencing, targeted Sanger sequencing and multiplex ligation-dependent probe amplification analysis were used to study 68 adult patients with progressive external ophthalmoplegia either with or without multiple mitochondrial DNA deletions in skeletal muscle. Nine patients (eight probands) were found to carry compound heterozygous SPG7 mutations, including three novel mutations: two missense mutations c.2221G>A; p.(Glu741Lys), c.2224G>A; p.(Asp742Asn), a truncating mutation c.861dupT; p.Asn288*, and seven previously reported mutations. We identified a further six patients with single heterozygous mutations in SPG7, including two further novel mutations: c.184-3C>T (predicted to remove a splice site before exon 2) and c.1067C>T; p.(Thr356Met). The clinical phenotype typically developed in mid-adult life with either progressive external ophthalmoplegia/ptosis and spastic ataxia, or a progressive ataxic disorder. Dysphagia and proximal myopathy were common, but urinary symptoms were rare, despite the spasticity. Functional studies included transcript analysis, proteomics, mitochondrial network analysis, single fibre mitochondrial DNA analysis and deep re-sequencing of mitochondrial DNA. SPG7 mutations caused increased mitochondrial biogenesis in patient muscle, and mitochondrial fusion in patient fibroblasts associated with the clonal expansion of mitochondrial DNA mutations. In conclusion, the SPG7 gene should be screened in patients in whom a disorder of mitochondrial DNA maintenance is suspected when spastic ataxia is prominent. The complex neurological phenotype is likely a result of the clonal expansion of secondary mitochondrial DNA mutations modulating the phenotype, driven by compensatory mitochondrial biogenesis.
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Affiliation(s)
- Gerald Pfeffer
- 1 Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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Matilla-Dueñas A, Ashizawa T, Brice A, Magri S, McFarland KN, Pandolfo M, Pulst SM, Riess O, Rubinsztein DC, Schmidt J, Schmidt T, Scoles DR, Stevanin G, Taroni F, Underwood BR, Sánchez I. Consensus paper: pathological mechanisms underlying neurodegeneration in spinocerebellar ataxias. CEREBELLUM (LONDON, ENGLAND) 2014; 13:269-302. [PMID: 24307138 PMCID: PMC3943639 DOI: 10.1007/s12311-013-0539-y] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Intensive scientific research devoted in the recent years to understand the molecular mechanisms or neurodegeneration in spinocerebellar ataxias (SCAs) are identifying new pathways and targets providing new insights and a better understanding of the molecular pathogenesis in these diseases. In this consensus manuscript, the authors discuss their current views on the identified molecular processes causing or modulating the neurodegenerative phenotype in spinocerebellar ataxias with the common opinion of translating the new knowledge acquired into candidate targets for therapy. The following topics are discussed: transcription dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, RNA toxicity, modulators of neurodegeneration and current therapeutic approaches. Overall point of consensus includes the common vision of neurodegeneration in SCAs as a multifactorial, progressive and reversible process, at least in early stages. Specific points of consensus include the role of the dysregulation of protein folding, transcription, bioenergetics, calcium handling and eventual cell death with apoptotic features of neurons during SCA disease progression. Unresolved questions include how the dysregulation of these pathways triggers the onset of symptoms and mediates disease progression since this understanding may allow effective treatments of SCAs within the window of reversibility to prevent early neuronal damage. Common opinions also include the need for clinical detection of early neuronal dysfunction, for more basic research to decipher the early neurodegenerative process in SCAs in order to give rise to new concepts for treatment strategies and for the translation of the results to preclinical studies and, thereafter, in clinical practice.
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Affiliation(s)
- A Matilla-Dueñas
- Health Sciences Research Institute Germans Trias i Pujol (IGTP), Ctra. de Can Ruti, Camí de les Escoles s/n, Badalona, Barcelona, Spain,
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Votsi C, Christodoulou K. Molecular diagnosis of autosomal recessive cerebellar ataxia in the whole exome/genome sequencing era. World J Neurol 2013; 3:115-128. [DOI: 10.5316/wjn.v3.i4.115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/30/2013] [Accepted: 10/16/2013] [Indexed: 02/06/2023] Open
Abstract
Autosomal recessive cerebellar ataxias (ARCA) are a clinically and genetically heterogeneous group of rare neurodegenerative disorders characterized by autosomal recessive inheritance and an early age of onset. Progressive ataxia is usually the prominent symptom and is often associated with other neurological or additional features. ARCA classification still remains controversial even though different approaches have been proposed over the years. Furthermore, ARCA molecular diagnosis has been a challenge due to phenotypic overlap and increased genetic heterogeneity observed within this group of disorders. Friedreich’s ataxia and ataxia telangiectasia have been reported as the most frequent and well-studied forms of ARCA. Significant progress in understanding the genetic etiologies of the ARCA has been achieved during the last 15 years. The methodological revolution that has been observed in genetics over the last few years has contributed significantly to the molecular diagnosis of rare diseases including the ARCAs. Development of high throughput technologies has resulted in the identification of new ARCA genes and novel mutations in known ARCA genes. Therefore, an improvement in the molecular diagnosis of ARCA is expected. Moreover, based on the fact that many patients still remain undiagnosed, additional forms of ataxia are expected to be identified. We hereby review the current knowledge on the ARCAs, focused on the genetic findings of the most common forms that were molecularly characterized before the whole exome/genome era, as well as the most recently described forms that have been elucidated with the use of these novel technologies. The significant contribution of whole-exome sequencing or whole-genome sequencing in the molecular diagnosis of ARCAs is discussed.
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A novel missense mutation in AFG3L2 associated with late onset and slow progression of spinocerebellar ataxia type 28. J Mol Neurosci 2013; 52:493-6. [PMID: 24293060 DOI: 10.1007/s12031-013-0187-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 11/15/2013] [Indexed: 12/12/2022]
Abstract
SCA28 is caused by mutations in the AFG3L2 gene. This gene encodes a subunit of the mitochondrial metalloprotease AFG3L2 (AFG3-like protein 2). Clinical features of SCA28 include slow to moderate progressive ataxia, dysarthria, and additional symptoms such as nystagmus, slow saccades, and increased deep tendon reflexes. Here, we report on a novel AFG3L2 mutation in a patient with slowly progressive ataxia and a positive family history. The nucleotide change results in the substitution of an evolutionarily highly conserved tyrosine by histidine (p.Y689H) in the M41 peptidase domain of AFG3L2.
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Musova Z, Kaiserova M, Kriegova E, Fillerova R, Vasovcak P, Santava A, Mensikova K, Zumrova A, Krepelova A, Sedlacek Z, Kanovsky P. A Novel Frameshift Mutation in the AFG3L2 Gene in a Patient with Spinocerebellar Ataxia. THE CEREBELLUM 2013; 13:331-7. [DOI: 10.1007/s12311-013-0538-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Gispert S, Parganlija D, Klinkenberg M, Dröse S, Wittig I, Mittelbronn M, Grzmil P, Koob S, Hamann A, Walter M, Büchel F, Adler T, Hrabé de Angelis M, Busch DH, Zell A, Reichert AS, Brandt U, Osiewacz HD, Jendrach M, Auburger G. Loss of mitochondrial peptidase Clpp leads to infertility, hearing loss plus growth retardation via accumulation of CLPX, mtDNA and inflammatory factors. Hum Mol Genet 2013; 22:4871-87. [PMID: 23851121 PMCID: PMC7108587 DOI: 10.1093/hmg/ddt338] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The caseinolytic peptidase P (CLPP) is conserved from bacteria to humans. In the mitochondrial matrix, it multimerizes and forms a macromolecular proteasome-like cylinder together with the chaperone CLPX. In spite of a known relevance for the mitochondrial unfolded protein response, its substrates and tissue-specific roles are unclear in mammals. Recessive CLPP mutations were recently observed in the human Perrault variant of ovarian failure and sensorineural hearing loss. Here, a first characterization of CLPP null mice demonstrated complete female and male infertility and auditory deficits. Disrupted spermatogenesis already at the spermatid stage and ovarian follicular differentiation failure were evident. Reduced pre-/post-natal survival and marked ubiquitous growth retardation contrasted with only light impairment of movement and respiratory activities. Interestingly, the mice showed resistance to ulcerative dermatitis. Systematic expression studies detected up-regulation of other mitochondrial chaperones, accumulation of CLPX and mtDNA as well as inflammatory factors throughout tissues. T-lymphocytes in the spleen were activated. Thus, murine Clpp deletion represents a faithful Perrault model. The disease mechanism probably involves deficient clearance of mitochondrial components and inflammatory tissue destruction.
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Abstract
Zusammenfassung
Hereditäre Ataxien stellen aufgrund der Vielfalt der möglichen genetischen Ursachen eine große diagnostische Herausforderung für die medizinische Genetik dar. Dieses Problem wird dadurch verstärkt, dass zwar die Zahl der neu identifizierten Gene in den letzten 3 Jahren durch neue Sequenziertechnologien rasant zugenommen hat, häufig jedoch nur wenige Familien weltweit Mutationen in diesen Genen aufweisen, d. h. sie extrem selten sind. Der vorliegende Artikel gibt eine Übersicht über dominante und rezessive Ataxien und berücksichtigt dabei auch die neu identifizierten Ataxie-Gene. Um den Anforderungen einer praktisch-orientierten genetischen Diagnostik gerecht zu werden, versuchen wir dabei auch, Häufigkeitseinschätzungen der betroffenen Genorte zu geben und – sofern möglich – phänotypische Eigenschaften und Biomarker zu definieren, die eine genetische Diagnostik erfolgversprechend leiten können, insbesondere bei rezessiven Ataxien. Diese diagnostischen Indikatoren werden in Form von diagnostischen Pfaden zusammengefasst, die eine Orientierung bei der mehrstufigen genetischen Diagnostik dominanter und rezessiver Ataxien geben sollen. Aufgrund der Vielzahl der Genkandidaten und des großen phänotypischen Überlappungsbereichs wird es in den meisten Fällen jedoch am zeiteffizientesten und kostengünstigsten sein, Panel-Untersuchungen mittels Next-Generation-Sequencing-Technologien durchzuführen.
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Affiliation(s)
- M. Synofzik
- Aff1 grid.10392.39 0000000121901447 Sektion für Klinische Neurogenetik, Abteilung für Neurodegeneration, Zentrum für Neurologie, Hertie-Institut für Klinische Hirnforschung Universität Tübingen Hoppe-Seyler-Str. 3 72076 Tübingen Deutschland
- Aff2 grid.424247.3 0000 0004 0438 0426 Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Tübingen Deutschland
| | - L. Schöls
- Aff1 grid.10392.39 0000000121901447 Sektion für Klinische Neurogenetik, Abteilung für Neurodegeneration, Zentrum für Neurologie, Hertie-Institut für Klinische Hirnforschung Universität Tübingen Hoppe-Seyler-Str. 3 72076 Tübingen Deutschland
- Aff2 grid.424247.3 0000 0004 0438 0426 Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Tübingen Deutschland
| | - O. Riess
- Aff3 Institut für Medizinische Genetik und Angewandte Genomik Tübingen Deutschland
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Genome-wide expression profiling and functional characterization of SCA28 lymphoblastoid cell lines reveal impairment in cell growth and activation of apoptotic pathways. BMC Med Genomics 2013; 6:22. [PMID: 23777634 PMCID: PMC3689607 DOI: 10.1186/1755-8794-6-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 06/05/2013] [Indexed: 11/10/2022] Open
Abstract
Background SCA28 is an autosomal dominant ataxia associated with AFG3L2 gene mutations. We performed a whole genome expression profiling using lymphoblastoid cell lines (LCLs) from four SCA28 patients and six unrelated healthy controls matched for sex and age. Methods Gene expression was evaluated with the Affymetrix GeneChip Human Genome U133A 2.0 Arrays and data were validated by real-time PCR. Results We found 66 genes whose expression was statistically different in SCA28 LCLs, 35 of which were up-regulated and 31 down-regulated. The differentially expressed genes were clustered in five functional categories: (1) regulation of cell proliferation; (2) regulation of programmed cell death; (3) response to oxidative stress; (4) cell adhesion, and (5) chemical homeostasis. To validate these data, we performed functional experiments that proved an impaired SCA28 LCLs growth compared to controls (p < 0.005), an increased number of cells in the G0/G1 phase (p < 0.001), and an increased mortality because of apoptosis (p < 0.05). We also showed that respiratory chain activity and reactive oxygen species levels was not altered, although lipid peroxidation in SCA28 LCLs was increased in basal conditions (p < 0.05). We did not detect mitochondrial DNA large deletions. An increase of TFAM, a crucial protein for mtDNA maintenance, and of DRP1, a key regulator of mitochondrial dynamic mechanism, suggested an alteration of fission/fusion pathways. Conclusions Whole genome expression profiling, performed on SCA28 LCLs, allowed us to identify five altered functional categories that characterize the SCA28 LCLs phenotype, the first reported in human cells to our knowledge.
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Rüb U, Schöls L, Paulson H, Auburger G, Kermer P, Jen JC, Seidel K, Korf HW, Deller T. Clinical features, neurogenetics and neuropathology of the polyglutamine spinocerebellar ataxias type 1, 2, 3, 6 and 7. Prog Neurobiol 2013; 104:38-66. [PMID: 23438480 DOI: 10.1016/j.pneurobio.2013.01.001] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 01/22/2013] [Accepted: 01/31/2013] [Indexed: 12/18/2022]
Abstract
The spinocerebellar ataxias type 1 (SCA1), 2 (SCA2), 3 (SCA3), 6 (SCA6) and 7 (SCA7) are genetically defined autosomal dominantly inherited progressive cerebellar ataxias (ADCAs). They belong to the group of CAG-repeat or polyglutamine diseases and share pathologically expanded and meiotically unstable glutamine-encoding CAG-repeats at distinct gene loci encoding elongated polyglutamine stretches in the disease proteins. In recent years, progress has been made in the understanding of the pathogenesis of these currently incurable diseases: Identification of underlying genetic mechanisms made it possible to classify the different ADCAs and to define their clinical and pathological features. Furthermore, advances in molecular biology yielded new insights into the physiological and pathophysiological role of the gene products of SCA1, SCA2, SCA3, SCA6 and SCA7 (i.e. ataxin-1, ataxin-2, ataxin-3, α-1A subunit of the P/Q type voltage-dependent calcium channel, ataxin-7). In the present review we summarize our current knowledge about the polyglutamine ataxias SCA1, SCA2, SCA3, SCA6 and SCA7 and compare their clinical and electrophysiological features, genetic and molecular biological background, as well as their brain pathologies. Furthermore, we provide an overview of the structure, interactions and functions of the different disease proteins. On the basis of these comprehensive data, similarities, differences and possible disease mechanisms are discussed.
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Affiliation(s)
- Udo Rüb
- Dr. Senckenberg Chronomedical Institute, Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt/Main, Germany.
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