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Zhang Y, Pang D, Wang Z, Ma L, Chen Y, Yang L, Xiao W, Yuan H, Chang F, Ouyang H. An integrative analysis of genotype-phenotype correlation in Charcot Marie Tooth type 2A disease with MFN2 variants: A case and systematic review. Gene 2023; 883:147684. [PMID: 37536398 DOI: 10.1016/j.gene.2023.147684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/24/2023] [Accepted: 07/31/2023] [Indexed: 08/05/2023]
Abstract
Dominant genetic variants in the mitofusin 2 (MFN2) gene lead to Charcot-Marie-Tooth type 2A (CMT2A), a neurodegenerative disease caused by genetic defects that directly damage axons. In this study, we reported a proband with a pathogenic variant in the GTPase domain of MFN2, c.494A > G (p.His165Arg). To date, at least 184 distinct MFN2 variants identified in 944 independent probands have been reported in 131 references. However, the field of medical genetics has long been challenged by how genetic variation in the MFN2 gene is associated with disease phenotypes. Here, by collating the MFN2 variant data and patient clinical information from Leiden Open Variant Database 3.0, NCBI clinvar database, and available related references in PubMed, we determined the mutation frequency, age of onset, sex ratio, and geographical distribution. Furthermore, the results of an analysis examining the relationship between variants and phenotypes from multiple genetic perspectives indicated that insertion and deletions (indels), copy number variants (CNVs), duplication variants, and nonsense mutations in single nucleotide variants (SNVs) tend to be pathogenic, and the results emphasized the importance of the GTPase domain to the structure and function of MFN2. Overall, three reliable classification methods of MFN2 genotype-phenotype associations provide insights into the prediction of CMT2A disease severity. Of course, there are still many MFN2 variants that have not been given clear clinical significance, which requires clinicians to make more accurate clinical diagnoses.
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Affiliation(s)
- Yuanzhu Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Daxin Pang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China; Chongqing Research Institute, Jilin University, Chongqing 401120, China; Chongqing Jitang Biotechnology Research Institute Co., Ltd., Chongqing 401120, China.
| | - Ziru Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Lerong Ma
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Yiwu Chen
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Lin Yang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Wenyu Xiao
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Hongming Yuan
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China; Chongqing Research Institute, Jilin University, Chongqing 401120, China.
| | - Fei Chang
- Department of Orthopedics, The Second Hospital of Jilin University, Changchun 130022, China.
| | - Hongsheng Ouyang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China; Chongqing Research Institute, Jilin University, Chongqing 401120, China; Chongqing Jitang Biotechnology Research Institute Co., Ltd., Chongqing 401120, China.
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2
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Stavropoulos F, Georgiou E, Schiza N, Bell S, Baloh RH, Kleopa KA, Sargiannidou I. Mitofusin 1 overexpression rescues the abnormal mitochondrial dynamics caused by the Mitofusin 2 K357T mutation in vitro. J Peripher Nerv Syst 2023; 28:329-340. [PMID: 37220142 DOI: 10.1111/jns.12564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/12/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Mitofusin 1 (MFN1) and MFN2 are outer mitochondrial membrane fusogenic proteins regulating mitochondrial network morphology. MFN2 mutations cause Charcot-Marie-Tooth type 2A (CMT2A), an axonal neuropathy characterized by mitochondrial fusion defects, which in the case of a GTPase domain mutant, were rescued following wild-type MFN1/2 (MFN1/2WT ) overexpression. In this study, we compared the therapeutic efficiency between MFN1WT and MFN2WT overexpression in correcting mitochondrial defects induced by the novel MFN2K357T mutation located in the highly conserved R3 region. METHODS Constructs expressing either MFN2K357T , MFN2WT , or MFN1WT under the ubiquitous chicken β-actin hybrid (CBh) promoter were generated. Flag or myc tag was used for their detection. Differentiated SH-SY5Y cells were single transfected with MFN1WT , MFN2WT , or MFN2K357T , as well as double transfected with MFN2K357T /MFN2WT or MFN2K357T /MFN1WT . RESULTS SH-SY5Y cells transfected with MFN2K357T exhibited severe perinuclear mitochondrial clustering with axon-like processes devoid of mitochondria. Single transfection with MFN1WT resulted in a more interconnected mitochondrial network than transfection with MFN2WT , accompanied by mitochondrial clusters. Double transfection of MFN2K357T with either MFN1WT or MFN2WT resolved the mutant-induced mitochondrial clusters and led to detectable mitochondria throughout the axon-like processes. MFN1WT showed higher efficacy than MFN2WT in rescuing these defects. INTERPRETATION These results further demonstrate the higher potential of MFN1WT over MFN2WT overexpression to rescue CMT2A-induced mitochondrial network abnormalities due to mutations outside the GTPase domain. This higher phenotypic rescue conferred by MFN1WT , possibly due to its higher mitochondrial fusogenic ability, may be applied to different CMT2A cases regardless of the MFN2 mutation type.
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Affiliation(s)
- Filippos Stavropoulos
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Elena Georgiou
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Natasa Schiza
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Shaughn Bell
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Robert H Baloh
- Global Head of Neuroscience, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, USA
| | - Kleopas A Kleopa
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Center for Neuromuscular Disorders and Center for Multiple Sclerosis and Related Disorders, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Irene Sargiannidou
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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3
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Abati E, Manini A, Velardo D, Del Bo R, Napoli L, Rizzo F, Moggio M, Bresolin N, Bellone E, Bassi MT, D'Angelo MG, Comi GP, Corti S. Clinical and genetic features of a cohort of patients with MFN2-related neuropathy. Sci Rep 2022; 12:6181. [PMID: 35418194 PMCID: PMC9008012 DOI: 10.1038/s41598-022-10220-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 04/05/2022] [Indexed: 11/09/2022] Open
Abstract
Charcot–Marie–Tooth disease type 2A (CMT2A) is a rare inherited axonal neuropathy caused by mutations in MFN2 gene, which encodes Mitofusin 2, a transmembrane protein of the outer mitochondrial membrane. We performed a cross-sectional analysis on thirteen patients carrying mutations in MFN2, from ten families, describing their clinical and genetic characteristics. Evaluated patients presented a variable age of onset and a wide phenotypic spectrum, with most patients presenting a severe phenotype. A novel heterozygous missense variant was detected, p.K357E. It is located at a highly conserved position and predicted as pathogenic by in silico tools. At a clinical level, the p.K357E carrier shows a severe sensorimotor axonal neuropathy. In conclusion, our work expands the genetic spectrum of CMT2A, disclosing a novel mutation and its related clinical effect, and provides a detailed description of the clinical features of a cohort of patients with MFN2 mutations. Obtaining a precise genetic diagnosis in affected families is crucial both for family planning and prenatal diagnosis, and in a therapeutic perspective, as we are entering the era of personalized therapy for genetic diseases.
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Affiliation(s)
- Elena Abati
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy. .,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
| | - Arianna Manini
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Daniele Velardo
- Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Roberto Del Bo
- Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Laura Napoli
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Federica Rizzo
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Maurizio Moggio
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Nereo Bresolin
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Emilia Bellone
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (Dinogmi) - Medical Genetics, University of Genoa, Genoa, Italy
| | - Maria Teresa Bassi
- Laboratory of Molecular Biology, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Maria Grazia D'Angelo
- Neuromuscular Disorder Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Giacomo Pietro Comi
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefania Corti
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
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4
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Aberrant Mitochondrial Dynamics and Exacerbated Response to Neuroinflammation in a Novel Mouse Model of CMT2A. Int J Mol Sci 2021; 22:ijms222111569. [PMID: 34769001 PMCID: PMC8584238 DOI: 10.3390/ijms222111569] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/06/2021] [Accepted: 10/20/2021] [Indexed: 01/09/2023] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is the most common hereditary axonal neuropathy caused by mutations in MFN2 encoding Mitofusin-2, a multifunctional protein located in the outer mitochondrial membrane. In order to study the effects of a novel MFN2K357T mutation associated with early onset, autosomal dominant severe CMT2A, we generated a knock-in mouse model. While Mfn2K357T/K357T mouse pups were postnatally lethal, Mfn2+/K357T heterozygous mice were asymptomatic and had no histopathological changes in their sciatic nerves up to 10 months of age. However, immunofluorescence analysis of Mfn2+/K357T mice revealed aberrant mitochondrial clustering in the sciatic nerves from 6 months of age, in optic nerves from 8 months, and in lumbar spinal cord white matter at 10 months, along with microglia activation. Ultrastructural analyses confirmed dysmorphic mitochondrial aggregates in sciatic and optic nerves. After exposure of 6-month-old mice to lipopolysaccharide, Mfn2+/K357T mice displayed a higher immune response, a more severe motor impairment, and increased CNS inflammation, microglia activation, and macrophage infiltrates. Overall, ubiquitous Mfn2K357T expression renders the CNS and peripheral nerves of Mfn2+/K357T mice more susceptible to mitochondrial clustering, and augments their response to inflammation, modeling some cellular mechanisms that may be relevant for the development of neuropathy in patients with CMT2A.
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5
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Pellino G, Faggioli R, Galuppi A, Leon A, Fusco C, Tugnoli V, Suppiej A. Mitofusin 2: The missing link between mtDNA maintenance defects and neurotransmitter disorders. Mitochondrion 2021; 61:159-164. [PMID: 34600155 DOI: 10.1016/j.mito.2021.09.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 09/01/2021] [Accepted: 09/27/2021] [Indexed: 02/07/2023]
Abstract
Mitofusin (MFN) 2 belongs to the large family of mitochondrial transmembrane GTPases and has a role in dynamic mitochondrial remodeling process governed by fusion and fission. MFN2 pathogenic variants classically cause Charcot-Marie-Tooth disease type 2A (CMT2A), the most common axonal form of CMT, but patients with complex and unusual phenotypes involving the central and peripheral nervous system have been described, with mitochondrial dysfunction proposed as the underlying pathogenic mechanism. Here, we report the first description of a neurochemical pattern of secondary alterations in the metabolism of biogenic amines linked to the de novo presence of the hotspot MFN2 pathogenic variant p.Arg104Trp. The infant presented a very early onset choreic movement disorder associated with severe axial hypotonia and fluctuating dystonia of limbs. The relationship between mitochondrial DNA (mtDNA) maintenance defects and dopaminergic neurotransmitter disorders, governed by MFN2, is discussed.
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Affiliation(s)
- Giuditta Pellino
- Pediatric Unit, Azienda USL Ferrara - Sant'Anna University Hospital of Ferrara, Ferrara, Italy.
| | - Raffaella Faggioli
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
| | - Anna Galuppi
- Child Neurology Unit, Azienda USL Ferrara, Ferrara, Italy
| | - Alberta Leon
- Research & Innovation Srl (R&I Genetics), Padova, Italy
| | - Carlo Fusco
- Child Neurology and Psychiatric Unit-Presidio Ospedaliero Santa Maria Nuova - AUSL - IRCCS of Reggio Emilia, Reggio Emilia, Italy
| | - Valeria Tugnoli
- Department of Neuroscience and Rehabilitation, Division of Neurology, Sant'Anna University Hospital of Ferrara, Ferrara, Italy
| | - Agnese Suppiej
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
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6
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Sharma G, Pfeffer G, Shutt TE. Genetic Neuropathy Due to Impairments in Mitochondrial Dynamics. BIOLOGY 2021; 10:268. [PMID: 33810506 PMCID: PMC8066130 DOI: 10.3390/biology10040268] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/19/2021] [Accepted: 03/21/2021] [Indexed: 12/12/2022]
Abstract
Mitochondria are dynamic organelles capable of fusing, dividing, and moving about the cell. These properties are especially important in neurons, which in addition to high energy demand, have unique morphological properties with long axons. Notably, mitochondrial dysfunction causes a variety of neurological disorders including peripheral neuropathy, which is linked to impaired mitochondrial dynamics. Nonetheless, exactly why peripheral neurons are especially sensitive to impaired mitochondrial dynamics remains somewhat enigmatic. Although the prevailing view is that longer peripheral nerves are more sensitive to the loss of mitochondrial motility, this explanation is insufficient. Here, we review pathogenic variants in proteins mediating mitochondrial fusion, fission and transport that cause peripheral neuropathy. In addition to highlighting other dynamic processes that are impacted in peripheral neuropathies, we focus on impaired mitochondrial quality control as a potential unifying theme for why mitochondrial dysfunction and impairments in mitochondrial dynamics in particular cause peripheral neuropathy.
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Affiliation(s)
- Govinda Sharma
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| | - Gerald Pfeffer
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, Hotchkiss Brain Institute, Alberta Child Health Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| | - Timothy E. Shutt
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
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7
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Pipis M, Feely SME, Polke JM, Skorupinska M, Perez L, Shy RR, Laura M, Morrow JM, Moroni I, Pisciotta C, Taroni F, Vujovic D, Lloyd TE, Acsadi G, Yum SW, Lewis RA, Finkel RS, Herrmann DN, Day JW, Li J, Saporta M, Sadjadi R, Walk D, Burns J, Muntoni F, Ramchandren S, Horvath R, Johnson NE, Züchner S, Pareyson D, Scherer SS, Rossor AM, Shy ME, Reilly MM. Natural history of Charcot-Marie-Tooth disease type 2A: a large international multicentre study. Brain 2021; 143:3589-3602. [PMID: 33415332 PMCID: PMC7805791 DOI: 10.1093/brain/awaa323] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/28/2020] [Indexed: 01/02/2023] Open
Abstract
Mitofusin-2 (MFN2) is one of two ubiquitously expressed homologous proteins in eukaryote cells, playing a critical role in mitochondrial fusion. Mutations in MFN2 (most commonly autosomal dominant) cause Charcot-Marie-Tooth disease type 2A (CMT2A), the commonest axonal form of CMT, with significant allelic heterogeneity. Previous, moderately-sized, cross sectional genotype-phenotype studies of CMT2A have described the phenotypic spectrum of the disease, but longitudinal natural history studies are lacking. In this large multicentre prospective cohort study of 196 patients with dominant and autosomal recessive CMT2A, we present an in-depth genotype-phenotype study of the baseline characteristics of patients with CMT2A and longitudinal data (1–2 years) to describe the natural history. A childhood onset of autosomal dominant CMT2A is the most predictive marker of significant disease severity and is independent of the disease duration. When compared to adult onset autosomal dominant CMT2A, it is associated with significantly higher rates of use of ankle-foot orthoses, full-time use of wheelchair, dexterity difficulties and also has significantly higher CMT Examination Score (CMTESv2) and CMT Neuropathy Score (CMTNSv2) at initial assessment. Analysis of longitudinal data using the CMTESv2 and its Rasch-weighted counterpart, CMTESv2-R, show that over 1 year, the CMTESv2 increases significantly in autosomal dominant CMT2A (mean change 0.84 ± 2.42; two-tailed paired t-test P = 0.039). Furthermore, over 2 years both the CMTESv2 (mean change 0.97 ± 1.77; two-tailed paired t-test P = 0.003) and the CMTESv2-R (mean change 1.21 ± 2.52; two-tailed paired t-test P = 0.009) increase significantly with respective standardized response means of 0.55 and 0.48. In the paediatric CMT2A population (autosomal dominant and autosomal recessive CMT2A grouped together), the CMT Pediatric Scale increases significantly both over 1 year (mean change 2.24 ± 3.09; two-tailed paired t-test P = 0.009) and over 2 years (mean change 4.00 ± 3.79; two-tailed paired t-test P = 0.031) with respective standardized response means of 0.72 and 1.06. This cross-sectional and longitudinal study of the largest CMT2A cohort reported to date provides guidance for variant interpretation, informs prognosis and also provides natural history data that will guide clinical trial design.
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Affiliation(s)
- Menelaos Pipis
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Shawna M E Feely
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - James M Polke
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Mariola Skorupinska
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Laura Perez
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Rosemary R Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Matilde Laura
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Jasper M Morrow
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Isabella Moroni
- Department of Pediatric Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Pisciotta
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Franco Taroni
- Unit of Medical Genetics and Neurogenetics, Department of Diagnostics and Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Dragan Vujovic
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Thomas E Lloyd
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Gyula Acsadi
- Connecticut Children's Medical Center, Hartford, CT, USA
| | - Sabrina W Yum
- The Children's Hospital of Philadelphia, and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Richard A Lewis
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Richard S Finkel
- Center for Experimental Neurotherapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - David N Herrmann
- Department of Neurology, University of Rochester, Rochester, NY, USA
| | - John W Day
- Department of Neurology, Stanford Health Care, Stanford, CA, USA
| | - Jun Li
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Mario Saporta
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Reza Sadjadi
- Massachusetts General Hospital, Boston, Massachusetts, USA
| | - David Walk
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Joshua Burns
- University of Sydney School of Health Sciences and Children's Hospital at Westmead, Sydney, Australia
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, NIHR Biomedical Research Centre at UCL Great Ormond Street Institute of Child Health and Great Ormond Street Hospital, London, UK
| | | | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | | | - Stephan Züchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Davide Pareyson
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Steven S Scherer
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander M Rossor
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
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8
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Zhou Y, Carmona S, Muhammad AKMG, Bell S, Landeros J, Vazquez M, Ho R, Franco A, Lu B, Dorn GW, Wang S, Lutz CM, Baloh RH. Restoring mitofusin balance prevents axonal degeneration in a Charcot-Marie-Tooth type 2A model. J Clin Invest 2019; 129:1756-1771. [PMID: 30882371 DOI: 10.1172/jci124194] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/29/2019] [Indexed: 01/08/2023] Open
Abstract
Mitofusin-2 (MFN2) is a mitochondrial outer-membrane protein that plays a pivotal role in mitochondrial dynamics in most tissues, yet mutations in MFN2, which cause Charcot-Marie-Tooth disease type 2A (CMT2A), primarily affect the nervous system. We generated a transgenic mouse model of CMT2A that developed severe early onset vision loss and neurological deficits, axonal degeneration without cell body loss, and cytoplasmic and axonal accumulations of fragmented mitochondria. While mitochondrial aggregates were labeled for mitophagy, mutant MFN2 did not inhibit Parkin-mediated degradation, but instead had a dominant negative effect on mitochondrial fusion only when MFN1 was at low levels, as occurs in neurons. Finally, using a transgenic approach, we found that augmenting the level of MFN1 in the nervous system in vivo rescued all phenotypes in mutant MFN2R94Q-expressing mice. These data demonstrate that the MFN1/MFN2 ratio is a key determinant of tissue specificity in CMT2A and indicate that augmentation of MFN1 in the nervous system is a viable therapeutic strategy for the disease.
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Affiliation(s)
- Yueqin Zhou
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Sharon Carmona
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - A K M G Muhammad
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Shaughn Bell
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Jesse Landeros
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Michael Vazquez
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ritchie Ho
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Antonietta Franco
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Bin Lu
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Shaomei Wang
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | | | - Robert H Baloh
- Center for Neural Science and Medicine, and.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.,Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, California, USA
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9
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Molecular modelling of mitofusin 2 for a prediction for Charcot-Marie-Tooth 2A clinical severity. Sci Rep 2018; 8:16900. [PMID: 30442897 PMCID: PMC6237821 DOI: 10.1038/s41598-018-35133-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/31/2018] [Indexed: 12/30/2022] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is an autosomal dominant neuropathy caused by mutations in the mitofusin 2 gene (MFN2). More than 100 MFN2 gene mutations have been reported so far, with majority located within the GTPase domain encoding region. These domain-specific mutations present wide range of symptoms with differences associated with distinct amino acid substitutions in the same position. Due to the lack of conclusive phenotype-genotype correlation the predictive value of genetic results remains still limited. We have explored whether changes in the protein structure caused by MFN2 mutations can help to explain diseases phenotypes. Using a stable protein model, we evaluated the effect of 26 substitutions on the MFN2 structure and predicted the molecular consequences of such alterations. The observed changes were correlated with clinical features associated with a given mutation. Of all tested mutations positive correlation of molecular modelling with the clinical features reached 73%. Our analysis revealed that molecular modelling of mitofusin 2 mutations is a powerful tool, which predicts associated pathogenic impacts and that these correlate with clinical outcomes. This approach may aid an early diagnosis and prediction of symptoms severity in CMT2A patients.
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10
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Finsterer J, Fiorini AC, Scorza CA, Scorza FA. CMT2 due to homozygous MFN2 variants is a multiorgan mitochondrial disorder. Eur J Paediatr Neurol 2018; 22:889-891. [PMID: 29752145 DOI: 10.1016/j.ejpn.2018.04.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 04/24/2018] [Indexed: 10/17/2022]
Affiliation(s)
| | - Ana C Fiorini
- Programa de Estudos Pós-Graduado em Fonoaudiologia, Pontifícia Universidade Católica de São Paulo (PUC-SP), Departamento de Fonoaudiologia, Escola Paulista de Medicina/Universidade Federal de São Paul o (EPM/UNIFESP), São Paulo, Brazil.
| | - Carla A Scorza
- Disciplina de Neurociência, Escola Paulista de Medicina/Universidade Federal de São Paulo/. (EPM/UNIFESP), São Paulo, Brazil.
| | - Fulvio A Scorza
- Disciplina de Neurociência, Escola Paulista de Medicina/Universidade Federal de São Paulo/. (EPM/UNIFESP), São Paulo, Brazil
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11
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You Y, Wang X, Li S, Zhao X, Zhang X. Exome sequencing reveals a novel MFN2 missense mutation in a Chinese family with Charcot-Marie-Tooth type 2A. Exp Ther Med 2018; 16:2281-2286. [PMID: 30210586 PMCID: PMC6122517 DOI: 10.3892/etm.2018.6513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 06/08/2018] [Indexed: 12/20/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) is a group of inherited peripheral neuropathies. To date, mutations in >80 genes are reportedly associated with CMT. Protein mitofusin 2 encoded by MFN2 serves an essential role in mitochondrial fusion and regulation of apoptosis, which has previously been reported to be highly associated with an axonal form of neuropathy (CMT2A). In the present study, a large Chinese family with severe CMT was reported and a genetic analysis of the disease was performed. A detailed physical examination for CMT was performed in 13 family members and electrophysiological examinations were performed in 3 affected family members. Whole-exome sequencing was performed on the proband, and the suspected variants were identified by Sanger sequencing. The pathogenicity of mutation was verified by restriction fragment length polymorphism analysis in the family followed by a bioinformatics analysis. A novel c.1190G>C; p.(R397P) mutation in the MFN2 gene was identified in the proband, and co-segregated between genotype and phenotype in the family. The substituted amino acid changed the hydrophobicity and charge characteristics of the mitofusin 2 coiled-coiled domain; thus it may affect its biological function. In summary, a novel pathogenic mutation was identified in a Chinese family with CMT, which expands the phenotypic and mutational spectrum of CMT2A, and provides evidence for prenatal interventions and more precise pharmacological treatments to this family.
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Affiliation(s)
- Yi You
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, P.R. China
| | - Xiaodong Wang
- Department of Paediatric Orthopaedics, The Children's Hospital of Soochow University, Suzhou, Jiangsu 215000, P.R. China
| | - Shan Li
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, P.R. China
| | - Xiuli Zhao
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, P.R. China
| | - Xue Zhang
- Department of Medical Genetics, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, P.R. China
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12
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Tomaselli PJ, Kapoor M, Cortese A, Polke JM, Rossor AM, Reilly MM. Severe cognitive impairment in a patient with CMT2A. J Peripher Nerv Syst 2018. [PMID: 29520876 DOI: 10.1111/jns.12260] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pedro J Tomaselli
- MRC Centre for Neuromuscular Diseases and National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, UK.,Department of Neuromuscular Disorders, Clinical Hospital of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Mahima Kapoor
- MRC Centre for Neuromuscular Diseases and National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, UK
| | - Andrea Cortese
- MRC Centre for Neuromuscular Diseases and National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, UK
| | - James M Polke
- Department of Neurogenetics, The National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, UK
| | - Alexander M Rossor
- MRC Centre for Neuromuscular Diseases and National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, UK
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases and National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, UK
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13
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Ylikallio E, Woldegebriel R, Tumiati M, Isohanni P, Ryan MM, Stark Z, Walsh M, Sawyer SL, Bell KM, Oshlack A, Lockhart PJ, Shcherbii M, Estrada-Cuzcano A, Atkinson D, Hartley T, Tetreault M, Cuppen I, van der Pol WL, Candayan A, Battaloglu E, Parman Y, van Gassen KLI, van den Boogaard MJH, Boycott KM, Kauppi L, Jordanova A, Lönnqvist T, Tyynismaa H. MCM3AP in recessive Charcot-Marie-Tooth neuropathy and mild intellectual disability. Brain 2017. [PMID: 28633435 DOI: 10.1093/brain/awx138] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Defects in mRNA export from the nucleus have been linked to various neurodegenerative disorders. We report mutations in the gene MCM3AP, encoding the germinal center associated nuclear protein (GANP), in nine affected individuals from five unrelated families. The variants were associated with severe childhood onset primarily axonal (four families) or demyelinating (one family) Charcot-Marie-Tooth neuropathy. Mild to moderate intellectual disability was present in seven of nine affected individuals. The affected individuals were either compound heterozygous or homozygous for different MCM3AP variants, which were predicted to cause depletion of GANP or affect conserved amino acids with likely importance for its function. Accordingly, fibroblasts of affected individuals from one family demonstrated severe depletion of GANP. GANP has been described to function as an mRNA export factor, and to suppress TDP-43-mediated motor neuron degeneration in flies. Thus our results suggest defective mRNA export from nucleus as a potential pathogenic mechanism of axonal degeneration in these patients. The identification of MCM3AP variants in affected individuals from multiple centres establishes it as a disease gene for childhood-onset recessively inherited Charcot-Marie-Tooth neuropathy with intellectual disability.
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Affiliation(s)
- Emil Ylikallio
- Research Programs Unit, Molecular Neurology, University of Helsinki, 00290 Helsinki, Finland.,Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
| | - Rosa Woldegebriel
- Research Programs Unit, Molecular Neurology, University of Helsinki, 00290 Helsinki, Finland
| | - Manuela Tumiati
- Research Programs Unit, Genome-Scale Biology, University of Helsinki, 00290 Helsinki, Finland
| | - Pirjo Isohanni
- Research Programs Unit, Molecular Neurology, University of Helsinki, 00290 Helsinki, Finland.,Department of Child Neurology, Children's Hospital and Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
| | - Monique M Ryan
- Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia.,Royal Children's Hospital, Melbourne, Victoria, 3052, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, 3052, Australia
| | - Zornitza Stark
- Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia
| | - Maie Walsh
- Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia
| | - Sarah L Sawyer
- Department of Genetics and Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, K1H 8L1, Canada
| | - Katrina M Bell
- Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia
| | - Alicia Oshlack
- Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia
| | - Paul J Lockhart
- Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, 3052, Australia.,Bruce Lefroy Centre, Murdoch Childrens Research Institute, Melbourne, Victoria, 3052, Australia
| | - Mariia Shcherbii
- Research Programs Unit, Molecular Neurology, University of Helsinki, 00290 Helsinki, Finland
| | - Alejandro Estrada-Cuzcano
- Molecular Neurogenomics Group, VIB Department of Molecular Genetics, University of Antwerp, 2610 Antwerpen, Belgium
| | - Derek Atkinson
- Molecular Neurogenomics Group, VIB Department of Molecular Genetics, University of Antwerp, 2610 Antwerpen, Belgium
| | - Taila Hartley
- Department of Genetics and Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, K1H 8L1, Canada
| | - Martine Tetreault
- Department of Human Genetics, McGill University, Montreal, QC H3A 1B1, Canada.,McGill University and Genome Quebec Innovation Center, Montreal, QC H3A 1A4, Canada
| | - Inge Cuppen
- Department of Paediatric Neurology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands
| | - W Ludo van der Pol
- Brain Centre Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Centre Utrecht, 3508 Utrecht, The Netherlands
| | - Ayse Candayan
- Bogazici University, Department of Molecular Biology and Genetics, Istanbul, Turkey
| | - Esra Battaloglu
- Bogazici University, Department of Molecular Biology and Genetics, Istanbul, Turkey
| | - Yesim Parman
- Istanbul University, Istanbul Medical School, Department of Neurology, Istanbul, Turkey
| | - Koen L I van Gassen
- Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Kym M Boycott
- Department of Genetics and Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, K1H 8L1, Canada
| | - Liisa Kauppi
- Research Programs Unit, Genome-Scale Biology, University of Helsinki, 00290 Helsinki, Finland
| | - Albena Jordanova
- Molecular Neurogenomics Group, VIB Department of Molecular Genetics, University of Antwerp, 2610 Antwerpen, Belgium
| | - Tuula Lönnqvist
- Department of Child Neurology, Children's Hospital and Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
| | - Henna Tyynismaa
- Research Programs Unit, Molecular Neurology, University of Helsinki, 00290 Helsinki, Finland.,Department of Medical and Clinical Genetics, University of Helsinki, 00290 Helsinki, Finland
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14
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Valente AJ, Maddalena LA, Robb EL, Moradi F, Stuart JA. A simple ImageJ macro tool for analyzing mitochondrial network morphology in mammalian cell culture. Acta Histochem 2017; 119:315-326. [PMID: 28314612 DOI: 10.1016/j.acthis.2017.03.001] [Citation(s) in RCA: 426] [Impact Index Per Article: 60.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/07/2017] [Accepted: 03/03/2017] [Indexed: 01/08/2023]
Abstract
Mitochondria exist in a dynamic cycle of fusion and fission whose balance directly influences the morphology of the 'mitochondrial network', a term that encompasses the branched, reticular structure of fused mitochondria as well as the separate, punctate individual organelles within a eukaryotic cell. Over the past decade, the significance of the mitochondrial network has been increasingly appreciated, motivating the development of various approaches to analyze it. Here, we describe the Mitochondrial Network Analysis (MiNA) toolset, a relatively simple pair of macros making use of existing ImageJ plug-ins, allowing for semi-automated analysis of mitochondrial networks in cultured mammalian cells. MiNA is freely available at https://github.com/ScienceToolkit/MiNA. The tool incorporates optional preprocessing steps to enhance the quality of images before converting the images to binary and producing a morphological skeleton for calculating nine parameters to quantitatively capture the morphology of the mitochondrial network. The efficacy of the macro toolset is demonstrated using a sample set of images from SH-SY5Y, C2C12, and mouse embryo fibroblast (MEF) cell cultures treated under different conditions and exhibiting hyperfused, fused, and fragmented mitochondrial network morphologies.
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