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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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Small molecule agonist of mitochondrial fusion repairs mitochondrial dysfunction. Nat Chem Biol 2023; 19:468-477. [PMID: 36635564 DOI: 10.1038/s41589-022-01224-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 11/14/2022] [Indexed: 01/13/2023]
Abstract
Membrane dynamics are important to the integrity and function of mitochondria. Defective mitochondrial fusion underlies the pathogenesis of multiple diseases. The ability to target fusion highlights the potential to fight life-threatening conditions. Here we report a small molecule agonist, S89, that specifically promotes mitochondrial fusion by targeting endogenous MFN1. S89 interacts directly with a loop region in the helix bundle 2 domain of MFN1 to stimulate GTP hydrolysis and vesicle fusion. GTP loading or competition by S89 dislodges the loop from the GTPase domain and unlocks the molecule. S89 restores mitochondrial and cellular defects caused by mitochondrial DNA mutations, oxidative stress inducer paraquat, ferroptosis inducer RSL3 or CMT2A-causing mutations by boosting endogenous MFN1. Strikingly, S89 effectively eliminates ischemia/reperfusion (I/R)-induced mitochondrial damage and protects mouse heart from I/R injury. These results reveal the priming mechanism for MFNs and provide a therapeutic strategy for mitochondrial diseases when additional mitochondrial fusion is beneficial.
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3
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Sato-Yamada Y, Strickland A, Sasaki Y, Bloom J, DiAntonio A, Milbrandt J. A SARM1-mitochondrial feedback loop drives neuropathogenesis in a Charcot-Marie-Tooth disease type 2A rat model. J Clin Invest 2022; 132:e161566. [PMID: 36287202 PMCID: PMC9711878 DOI: 10.1172/jci161566] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 10/11/2022] [Indexed: 11/17/2022] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is an axonal neuropathy caused by mutations in the mitofusin 2 (MFN2) gene. MFN2 mutations result in profound mitochondrial abnormalities, but the mechanism underlying the axonal pathology is unknown. Sterile α and Toll/IL-1 receptor motif-containing 1 (SARM1), the central executioner of axon degeneration, can induce neuropathy and is activated by dysfunctional mitochondria. We tested the role of SARM1 in a rat model carrying a dominant CMT2A mutation (Mfn2H361Y) that exhibits progressive dying-back axonal degeneration, neuromuscular junction (NMJ) abnormalities, muscle atrophy, and mitochondrial abnormalities - all hallmarks of the human disease. We generated Sarm1-KO (Sarm1-/-) and Mfn2H361Y Sarm1 double-mutant rats and found that deletion of Sarm1 rescued axonal, synaptic, muscle, and functional phenotypes, demonstrating that SARM1 was responsible for much of the neuropathology in this model. Despite the presence of mutant MFN2 protein in these double-mutant rats, loss of SARM1 also dramatically suppressed many mitochondrial defects, including the number, size, and cristae density defects of synaptic mitochondria. This surprising finding indicates that dysfunctional mitochondria activated SARM1 and that activated SARM1 fed back on mitochondria to exacerbate the mitochondrial pathology. As such, this work identifies SARM1 inhibition as a therapeutic candidate for the treatment of CMT2A and other neurodegenerative diseases with prominent mitochondrial pathology.
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Affiliation(s)
- Yurie Sato-Yamada
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Advanced Oral Science, Niigata University Graduate School of Medical and Dental Science, Niigata City, Japan
| | - Amy Strickland
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Yo Sasaki
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Joseph Bloom
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
- Needleman Center for Neurometabolism and Axonal Therapeutics, St. Louis, Missouri, USA
| | - Aaron DiAntonio
- Needleman Center for Neurometabolism and Axonal Therapeutics, St. Louis, Missouri, USA
- Department of Developmental Biology and
| | - Jeffrey Milbrandt
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
- Needleman Center for Neurometabolism and Axonal Therapeutics, St. Louis, Missouri, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, USA
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4
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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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5
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Wu R, Lv H, Wang H, Wang Z, Yuan Y. The Pathological Features of Common Hereditary Mitochondrial Dynamics Neuropathy. Front Neurosci 2021; 15:705277. [PMID: 34366782 PMCID: PMC8341155 DOI: 10.3389/fnins.2021.705277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/28/2021] [Indexed: 01/02/2023] Open
Abstract
Objectives Mitofusin 2 and ganglioside-induced differentiation-associated protein 1 are two main mitochondrial dynamics-related proteins. Dysfunction of these two proteins leads to different subtypes of Charcot–Marie–Tooth disease type 2A (CMT2A) and CMT2K. This study aims to report the pathological difference between CMT2A and CMT2K in a large cohort. Methods Thirty patients with molecularly confirmed CMT2A and nine with CMT2K were identified by next-generation sequencing. Sural nerve biopsies were performed in 29 patients. Results The patients with both diseases showed length-dependent neuropathy with distal weakness, sensory loss, and no deep tendon reflex. Optic neuropathy appeared in 3/30 (10%) patients with CMT2A. Tendon contracture appeared in 4/9 (50.0%) patients with CMT2K. Sural biopsy revealed the loss of both myelinated and unmyelinated nerve fibers. Closely packed, irregularly oriented neurofilaments were observed in axons of unmyelinated nerve fibers in both diseases. Another important finding was the ubiquitous presence of smaller, rounded, and fragmented mitochondria in CMT2A and elongated mitochondria in CMT2K in the myelinated and unmyelinated axons. Conclusion This study confirmed large diversity in phenotypes between CMT2A and CMT2K. Mitochondrial dynamics-related variations can induce different mitochondrial morphological changes and neurofilament accumulation in axons.
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Affiliation(s)
- Rui Wu
- Department of Neurology, Peking University First Hospital, Beijing, China.,Department of Neurology, Shandong Provincial Hospital, Shandong University, Jinan, China
| | - He Lv
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Hui Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
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6
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Schiavon CR, Shadel GS, Manor U. Impaired Mitochondrial Mobility in Charcot-Marie-Tooth Disease. Front Cell Dev Biol 2021; 9:624823. [PMID: 33598463 PMCID: PMC7882694 DOI: 10.3389/fcell.2021.624823] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 01/05/2021] [Indexed: 12/13/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is a progressive, peripheral neuropathy and the most commonly inherited neurological disorder. Clinical manifestations of CMT mutations are typically limited to peripheral neurons, the longest cells in the body. Currently, mutations in at least 80 different genes are associated with CMT and new mutations are regularly being discovered. A large portion of the proteins mutated in axonal CMT have documented roles in mitochondrial mobility, suggesting that organelle trafficking defects may be a common underlying disease mechanism. This review will focus on the potential role of altered mitochondrial mobility in the pathogenesis of axonal CMT, highlighting the conceptional challenges and potential experimental and therapeutic opportunities presented by this "impaired mobility" model of the disease.
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Affiliation(s)
- Cara R. Schiavon
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Gerald S. Shadel
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
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7
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Chu X, Meng L, Zhang W, Luo J, Wang Z, Yuan Y. Peripheral Nervous System Involvement in Late-Onset Cobalamin C Disease? Front Neurol 2020; 11:594905. [PMID: 33324334 PMCID: PMC7726435 DOI: 10.3389/fneur.2020.594905] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 10/28/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Cobalamin C (cblC) has a fundamental role in both central and peripheral nervous system function at any age. Neurologic manifestations may be the earliest and often the only manifestation of hereditary or acquired cblC defect. Peripheral neuropathy remains a classical but underdiagnosed complication of cblC defect, especially in late-onset cblC disease caused by mutations in the methylmalonic aciduria type C and homocysteinemia (MMACHC) gene. So the clinical, electrophysiological, and pathological characteristics of late-onset cblC disease are not well-known. Methods: A retrospective study of patients with late-onset cblC disease was conducted at our hospital on a 3-year period. The neuropathy was confirmed by the nerve conduction study. Sural biopsies were performed in 2 patients. Results: Eight patients were identified, with a mean onset age of 16.25 ± 6.07 years. All patients had methylmalonic aciduria, homocysteinemia, compound heterozygous MMACHC gene mutations were detected in all patients, and 7/8 patients with c.482G>A mutation. One patient concomitant with homozygote c.665C>T mutation in 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. All patients showed limb weakness and cognitive impairment. Five patients had possible sensorimotor axonal polyneuropathy predominantly in the distal lower limbs. Sural biopsies showed loss of myelinated and unmyelinated fibers. Electro microscopy revealed crystalline-like inclusions bodies in Schwann cells and axonal degeneration. Conclusion: Late-onset cblC disease had possible heterogeneous group of distal axonal neuropathy. c.482G>A mutation is a hot spot mutation in late-onset cblC disease.
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Affiliation(s)
- Xujun Chu
- Department of Neurology, First Hospital, Peking University, Beijing, China
| | - Lingchao Meng
- Department of Neurology, First Hospital, Peking University, Beijing, China
| | - Wei Zhang
- Department of Neurology, First Hospital, Peking University, Beijing, China
| | - Jinjun Luo
- Department of Neurology, Temple University, Philadelphia, PA, United States
| | - Zhaoxia Wang
- Department of Neurology, First Hospital, Peking University, Beijing, China
| | - Yun Yuan
- Department of Neurology, First Hospital, Peking University, Beijing, China
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8
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Wu R, Fu J, Meng L, Lv H, Wang Z, Zhirong J, Yuan Y. Homozygous splice‐site mutation c.78 + 5G>A in
PMP22
causes congenital hypomyelinating neuropathy. Neuropathology 2019; 39:441-446. [PMID: 31777123 DOI: 10.1111/neup.12604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/24/2019] [Accepted: 08/25/2019] [Indexed: 01/10/2023]
Affiliation(s)
- Rui Wu
- Department of NeurologyPeking University First Hospital Beijing China
| | - Jun Fu
- Department of NeurologyPeking University First Hospital Beijing China
| | - Lingchao Meng
- Department of NeurologyPeking University First Hospital Beijing China
| | - He Lv
- Department of NeurologyPeking University First Hospital Beijing China
| | - Zhaoxia Wang
- Department of NeurologyPeking University First Hospital Beijing China
| | - Jia Zhirong
- Department of NeurologyPeking University First Hospital Beijing China
| | - Yun Yuan
- Department of NeurologyPeking University First Hospital Beijing China
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9
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Li J, Meng L, Wu R, Xie Z, Gang Q, Zhang W, Wang Z, Yuan Y. Sural nerve pathology in TFG-associated motor neuron disease with sensory neuropathy. Neuropathology 2019; 39:194-199. [PMID: 30957313 DOI: 10.1111/neup.12555] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 12/11/2022]
Abstract
The tropomyosin-receptor kinase fused gene (TFG) functions in vesicles formation and egress at the endoplasmic reticulum (ER). A heterozygous missense mutation c.854C > T (p.Pro285Leu) within TFG has been reported as causative for hereditary motor and sensory neuropathy with proximal predominance. Here, we describe two unrelated Chinese pedigrees with 13 affected members harboring the same variant. The clinical, electrophysiological and pathological findings are consistent with motor neuron disease with sensory neuropathy. The main symptoms were painful muscle cramps, slowly progressive proximal predominant weakness, muscle atrophy, fasciculation and distal sensory disturbance. Electromyography revealed widespread denervation and reinnervation. Sural nerve biopsy revealed severe loss of myelinated fibers. Electron microscopy revealed aggregation of ER with enlarged lumen and small vesicles in the remaining myelinated and unmyelinated axons. The mitochondria are smaller in Schwann cells and axons. Some unmyelinated axons showed disappearance of neurofilament and microtubular structures. This is the first report of c.854C > T mutation within TFG in Chinese population. Our findings not only extend the geographical and phenotypic spectrum of TFG-related neurological disorders, but also confirm the abnormalities of ER and mitochondria in sural nerves.
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Affiliation(s)
- Jia Li
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Lingchao Meng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Rui Wu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhiying Xie
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Qiang Gang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Wei Zhang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
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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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El Fissi N, Rojo M, Aouane A, Karatas E, Poliacikova G, David C, Royet J, Rival T. Mitofusin gain and loss of function drive pathogenesis in Drosophila models of CMT2A neuropathy. EMBO Rep 2018; 19:e45241. [PMID: 29898954 PMCID: PMC6073211 DOI: 10.15252/embr.201745241] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 05/16/2018] [Accepted: 05/23/2018] [Indexed: 11/09/2022] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is caused by dominant alleles of the mitochondrial pro-fusion factor Mitofusin 2 (MFN2). To address the consequences of these mutations on mitofusin activity and neuronal function, we generate Drosophila models expressing in neurons the two most frequent substitutions (R94Q and R364W, the latter never studied before) and two others localizing to similar domains (T105M and L76P). All alleles trigger locomotor deficits associated with mitochondrial depletion at neuromuscular junctions, decreased oxidative metabolism and increased mtDNA mutations, but they differently alter mitochondrial morphology and organization. Substitutions near or within the GTPase domain (R94Q, T105M) result in loss of function and provoke aggregation of unfused mitochondria. In contrast, mutations within helix bundle 1 (R364W, L76P) enhance mitochondrial fusion, as demonstrated by the rescue of mitochondrial alterations and locomotor deficits by over-expression of the fission factor DRP1. In conclusion, we show that both dominant negative and dominant active forms of mitofusin can cause CMT2A-associated defects and propose for the first time that excessive mitochondrial fusion drives CMT2A pathogenesis in a large number of patients.
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Affiliation(s)
| | - Manuel Rojo
- University of Bordeaux, CNRS, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR 5095, Bordeaux, France
| | - Aїcha Aouane
- Aix Marseille University, CNRS, IBDM, Marseille, France
| | - Esra Karatas
- University of Bordeaux, CNRS, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR 5095, Bordeaux, France
| | | | - Claudine David
- University of Bordeaux, CNRS, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR 5095, Bordeaux, France
| | - Julien Royet
- Aix Marseille University, CNRS, IBDM, Marseille, France
| | - Thomas Rival
- Aix Marseille University, CNRS, IBDM, Marseille, France
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12
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Wu R, Fu J, Meng L, Lv H, Wang Z, Yuan Y. Late-onset hereditary sensory and autonomic neuropathy expands the phenotypic spectrum of MFN2-related diseases. Neuropathology 2018; 38:463-467. [PMID: 30011089 DOI: 10.1111/neup.12487] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/05/2018] [Accepted: 06/04/2018] [Indexed: 12/22/2022]
Abstract
Mutations in the Mitofusin 2 (MFN2) gene have been identified in patients with autosomal dominant axonal motor and sensory neuropathy or Charcot-Marie-Tooth 2A (CMT2A). Here we describe clinical and pathological changes in an adult patient with sporadic hereditary sensory and autonomic neuropathy (HSAN) due to an MFN2 mutation. The patient was a 53-year-old man who had sensory involvement and anhidrosis in all limbs without motor features. The electrophysiological assessment documented severe axonal sensory neuropathy. The sural nerve biopsy confirmed the electrophysiological findings, revealing severe loss of myelinated and unmyelinated fibers with regeneration clusters. Genetic analysis revealed the previously identified mutation c.776 G > A in MFN2. Our report expands the phenotypic spectrum of MFN2-related diseases. Sequencing of MFN2 should be considered in all patients presenting with late-onset HSAN.
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Affiliation(s)
- Rui Wu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Jun Fu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Lingchao Meng
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - He Lv
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
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13
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Meyer JN, Leuthner TC, Luz AL. Mitochondrial fusion, fission, and mitochondrial toxicity. Toxicology 2017; 391:42-53. [PMID: 28789970 PMCID: PMC5681418 DOI: 10.1016/j.tox.2017.07.019] [Citation(s) in RCA: 313] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 07/10/2017] [Accepted: 07/31/2017] [Indexed: 12/17/2022]
Abstract
Mitochondrial dynamics are regulated by two sets of opposed processes: mitochondrial fusion and fission, and mitochondrial biogenesis and degradation (including mitophagy), as well as processes such as intracellular transport. These processes maintain mitochondrial homeostasis, regulate mitochondrial form, volume and function, and are increasingly understood to be critical components of the cellular stress response. Mitochondrial dynamics vary based on developmental stage and age, cell type, environmental factors, and genetic background. Indeed, many mitochondrial homeostasis genes are human disease genes. Emerging evidence indicates that deficiencies in these genes often sensitize to environmental exposures, yet can also be protective under certain circumstances. Inhibition of mitochondrial dynamics also affects elimination of irreparable mitochondrial DNA (mtDNA) damage and transmission of mtDNA mutations. We briefly review the basic biology of mitodynamic processes with a focus on mitochondrial fusion and fission, discuss what is known and unknown regarding how these processes respond to chemical and other stressors, and review the literature on interactions between mitochondrial toxicity and genetic variation in mitochondrial fusion and fission genes. Finally, we suggest areas for future research, including elucidating the full range of mitodynamic responses from low to high-level exposures, and from acute to chronic exposures; detailed examination of the physiological consequences of mitodynamic alterations in different cell types; mechanism-based testing of mitotoxicant interactions with interindividual variability in mitodynamics processes; and incorporating other environmental variables that affect mitochondria, such as diet and exercise.
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Affiliation(s)
- Joel N Meyer
- Nicholas School of the Environment and Integrated Toxicology and Environmental Health Program, Duke University, Durham, NC 27708-0328, United States.
| | - Tess C Leuthner
- Nicholas School of the Environment and Integrated Toxicology and Environmental Health Program, Duke University, Durham, NC 27708-0328, United States.
| | - Anthony L Luz
- Nicholas School of the Environment and Integrated Toxicology and Environmental Health Program, Duke University, Durham, NC 27708-0328, United States.
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14
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Similar clinical, pathological, and genetic features in Chinese patients with autosomal recessive and dominant Charcot–Marie–Tooth disease type 2K. Neuromuscul Disord 2017; 27:760-765. [DOI: 10.1016/j.nmd.2017.04.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 03/24/2017] [Accepted: 04/04/2017] [Indexed: 11/22/2022]
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15
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Luz AL, Godebo TR, Smith LL, Leuthner TC, Maurer LL, Meyer JN. Deficiencies in mitochondrial dynamics sensitize Caenorhabditis elegans to arsenite and other mitochondrial toxicants by reducing mitochondrial adaptability. Toxicology 2017; 387:81-94. [PMID: 28602540 PMCID: PMC5535741 DOI: 10.1016/j.tox.2017.05.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Revised: 05/10/2017] [Accepted: 05/30/2017] [Indexed: 01/06/2023]
Abstract
Mitochondrial fission, fusion, and mitophagy are interlinked processes that regulate mitochondrial shape, number, and size, as well as metabolic activity and stress response. The fundamental importance of these processes is evident in the fact that mutations in fission (DRP1), fusion (MFN2, OPA1), and mitophagy (PINK1, PARK2) genes can cause human disease (collectively >1/10,000). Interestingly, however, the age of onset and severity of clinical manifestations varies greatly between patients with these diseases (even those harboring identical mutations), suggesting a role for environmental factors in the development and progression of certain mitochondrial diseases. Using the model organism Caenorhabditis elegans, we screened ten mitochondrial toxicants (2, 4-dinitrophenol, acetaldehyde, acrolein, aflatoxin B1, arsenite, cadmium, cisplatin, doxycycline, paraquat, rotenone) for increased or decreased toxicity in fusion (fzo-1, eat-3)-, fission (drp-1)-, and mitophagy (pdr-1, pink-1)-deficient nematodes using a larval growth assay. In general, fusion-deficient nematodes were the most sensitive to toxicants, including aflatoxin B1, arsenite, cisplatin, paraquat, and rotenone. Because arsenite was particularly potent in fission- and fusion-deficient nematodes, and hundreds of millions of people are chronically exposed to arsenic, we investigated the effects of these genetic deficiencies on arsenic toxicity in more depth. We found that deficiencies in fission and fusion sensitized nematodes to arsenite-induced lethality throughout aging. Furthermore, low-dose arsenite, which acted in a "mitohormetic" fashion by increasing mitochondrial function (in particular, basal and maximal oxygen consumption) in wild-type nematodes by a wide range of measures, exacerbated mitochondrial dysfunction in fusion-deficient nematodes. Analysis of multiple mechanistic changes suggested that disruption of pyruvate metabolism and Krebs cycle activity underlie the observed arsenite-induced mitochondrial deficits, and these disruptions are exacerbated in the absence of mitochondrial fusion. This research demonstrates the importance of mitochondrial dynamics in limiting arsenite toxicity by permitting mitochondrial adaptability. It also suggests that individuals suffering from deficiencies in mitodynamic processes may be more susceptible to the mitochondrial toxicity of arsenic and other toxicants.
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Affiliation(s)
- Anthony L Luz
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Tewodros R Godebo
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Latasha L Smith
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Tess C Leuthner
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA
| | - Laura L Maurer
- ExxonMobil Biomedical Sciences, Inc., Annandale, NJ, 08801-3059, USA
| | - Joel N Meyer
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC, 27708, USA.
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16
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Xie Y, Li X, Liu L, Hu Z, Huang S, Zhan Y, Zi X, Xia K, Tang B, Zhang R. MFN2-related genetic and clinical features in a cohort of Chinese CMT2 patients. J Peripher Nerv Syst 2016; 21:38-44. [PMID: 26801520 DOI: 10.1111/jns.12159] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 01/10/2016] [Accepted: 01/18/2016] [Indexed: 12/01/2022]
Abstract
Charcot-Marie-Tooth disease 2A (CMT2A), caused by mutations in the mitofusin 2 gene (MFN2), is the most common CMT2 subtype. The aim of our study is to assess the frequency and summarize the genetic and clinical characteristics of Chinese CMT2A patients. A total of 17 coding exons of MFN2 were detected by direct sequencing in 82 unrelated Chinese families diagnosed as CMT2. Clinical evaluations were analyzed among CMT2A patients. We identified 14 missense variants in 9 sporadic and 6 familial cases, including four novel mutations (T129A, S249F, Q367P, and Q674L), 4 known mutations (R94W, R94Q, T105M, C132Y, M376V and Q751X), and 4 rare missense variants (K120E, C217F, K307E and T356S). A total of 23 patients had early-onset phenotype. Two patients had a CMTNS score of 0 to 10; 16 had a score of 11 to 20; and 7 had a score greater than 20. Five patients were confirmed a de novo origin. Six of 14 variants were located or closed to the GTPase domain. We report four novel mutations and four rare missense variants. MFN2 mutations account for 18% of CMT2 families in mainland China. The common characteristics of Chinese pedigree are early disease onset and moderate phenotypes.
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Affiliation(s)
- Yongzhi Xie
- Department of Neurology, the Third Xiangya Hospital, Changsha, China
| | - Xiaobo Li
- Department of Neurology, the Third Xiangya Hospital, Changsha, China
| | - Lei Liu
- Department of Neurology, the Third Xiangya Hospital, Changsha, China
| | - Zhengmao Hu
- National Key Lab of Medical Genetics, Central South University, Changsha, China
| | - Shunxiang Huang
- Department of Neurology, the Third Xiangya Hospital, Changsha, China
| | - Yajin Zhan
- Department of Neurology, the Third Xiangya Hospital, Changsha, China
| | - Xiaohong Zi
- Department of Neurology, the Third Xiangya Hospital, Changsha, China
| | - Kun Xia
- National Key Lab of Medical Genetics, Central South University, Changsha, China
| | - Beisha Tang
- National Key Lab of Medical Genetics, Central South University, Changsha, China
| | - Ruxu Zhang
- Department of Neurology, the Third Xiangya Hospital, Changsha, China
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17
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Mitofusin-2 is required for mouse oocyte meiotic maturation. Sci Rep 2016; 6:30970. [PMID: 27485634 PMCID: PMC4971528 DOI: 10.1038/srep30970] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 07/12/2016] [Indexed: 01/25/2023] Open
Abstract
Mitofusin-2 (Mfn2) is essential for embryonic development, anti-apoptotic events, protection against free radical-induced lesions, and mitochondrial fusion in many cells. However, little is known about its mechanism and function during oocyte maturation. In this study, we found that Mfn2 was expressed in the cytoplasm during different stages of mouse oocyte maturation. Mfn2 was mainly associated with α-tubulin during oocyte maturation. Knockdown of Mfn2 by specific siRNA injection into oocytes caused the mitochondrial morphology and quantity to change, resulting in severely defective spindles and misaligned chromosomes. This led to metaphase I arrest and the failure of first polar body extrusion. Furthermore, Mfn2 depletion from GV stage oocytes caused the redistribution of p38 MAPK in oocyte cytoplasm. These findings provide insights into potential mechanisms of Mfn2-mediated cellular alterations, which may have significant implications for oocyte maturation.
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18
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Transcriptional profiling revealed the anti-proliferative effect of MFN2 deficiency and identified risk factors in lung adenocarcinoma. Tumour Biol 2016; 37:8643-55. [DOI: 10.1007/s13277-015-4702-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 12/20/2015] [Indexed: 01/11/2023] Open
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