1
|
Chevrollier A, Bonnard AA, Ruaud L, Gueguen N, Perrin L, Desquiret-Dumas V, Guimiot F, Becker PH, Levy J, Reynier P, Gaignard P. Homozygous MFN2 variants causing severe antenatal encephalopathy with clumped mitochondria. Brain 2024; 147:91-99. [PMID: 37804319 DOI: 10.1093/brain/awad347] [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: 07/03/2023] [Revised: 08/30/2023] [Accepted: 09/25/2023] [Indexed: 10/09/2023] Open
Abstract
Pathogenic variants in the MFN2 gene are commonly associated with autosomal dominant (CMT2A2A) or recessive (CMT2A2B) Charcot-Marie-Tooth disease, with possible involvement of the CNS. Here, we present a case of severe antenatal encephalopathy with lissencephaly, polymicrogyria and cerebellar atrophy. Whole genome analysis revealed a homozygous deletion c.1717-274_1734 del (NM_014874.4) in the MFN2 gene, leading to exon 16 skipping and in-frame loss of 50 amino acids (p.Gln574_Val624del), removing the proline-rich domain and the transmembrane domain 1 (TM1). MFN2 is a transmembrane GTPase located on the mitochondrial outer membrane that contributes to mitochondrial fusion, shaping large mitochondrial networks within cells. In silico modelling showed that the loss of the TM1 domain resulted in a drastically altered topological insertion of the protein in the mitochondrial outer membrane. Fetus fibroblasts, investigated by fluorescent cell imaging, electron microscopy and time-lapse recording, showed a sharp alteration of the mitochondrial network, with clumped mitochondria and clusters of tethered mitochondria unable to fuse. Multiple deficiencies of respiratory chain complexes with severe impairment of complex I were also evidenced in patient fibroblasts, without involvement of mitochondrial DNA instability. This is the first reported case of a severe developmental defect due to MFN2 deficiency with clumped mitochondria.
Collapse
Affiliation(s)
- Arnaud Chevrollier
- MitoVasc Unit, INSERM U1083, CNRS 6015, SFR-ICAT, Angers University, MitoLab Team, 49000 Angers, France
| | - Adeline Alice Bonnard
- Department of Genetics, APHP Nord, Robert Debré University Hospital, 75019 Paris, France
- INSERM UMR 1131, Saint-Louis Research Institute, Paris University, 75010 Paris, France
| | - Lyse Ruaud
- Department of Genetics, APHP Nord, Robert Debré University Hospital, 75019 Paris, France
- INSERM UMR 1141, Paris-Cité University, NeuroDiderot, 75019 Paris, France
| | - Naïg Gueguen
- MitoVasc Unit, INSERM U1083, CNRS 6015, SFR-ICAT, Angers University, MitoLab Team, 49000 Angers, France
- Department of Biochemistry and Molecular biology, Angers University Hospital, 49000 Angers, France
| | - Laurence Perrin
- Department of Genetics, APHP Nord, Robert Debré University Hospital, 75019 Paris, France
| | - Valérie Desquiret-Dumas
- MitoVasc Unit, INSERM U1083, CNRS 6015, SFR-ICAT, Angers University, MitoLab Team, 49000 Angers, France
- Department of Biochemistry and Molecular biology, Angers University Hospital, 49000 Angers, France
| | - Fabien Guimiot
- INSERM UMR 1141, Paris-Cité University, NeuroDiderot, 75019 Paris, France
- Genetic department, CHU Robert Debre, Fetal Pathology Unit, 75019 Paris, France
| | - Pierre-Hadrien Becker
- Multi-site medical biology laboratory SeqOIA-FMG2025, 75014 Paris, France
- APHP Paris-Saclay, Department of Biochemistry, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, 94275 Le Kremlin-Bicêtre, France
| | - Jonathan Levy
- Department of Genetics, APHP Nord, Robert Debré University Hospital, 75019 Paris, France
- Multi-site medical biology laboratory SeqOIA-FMG2025, 75014 Paris, France
| | - Pascal Reynier
- MitoVasc Unit, INSERM U1083, CNRS 6015, SFR-ICAT, Angers University, MitoLab Team, 49000 Angers, France
- Department of Biochemistry and Molecular biology, Angers University Hospital, 49000 Angers, France
| | - Pauline Gaignard
- Multi-site medical biology laboratory SeqOIA-FMG2025, 75014 Paris, France
- APHP Paris-Saclay, Department of Biochemistry, Reference Center for Mitochondrial Disease, FILNEMUS, Bicêtre University Hospital, 94275 Le Kremlin-Bicêtre, France
| |
Collapse
|
2
|
Wong YC, Jayaraj ND, Belton TB, Shum GC, Ball HE, Ren D, Tadenev ALD, Krainc D, Burgess RW, Menichella DM. Misregulation of mitochondria-lysosome contact dynamics in Charcot-Marie-Tooth Type 2B disease Rab7 mutant sensory peripheral neurons. Proc Natl Acad Sci U S A 2023; 120:e2313010120. [PMID: 37878717 PMCID: PMC10622892 DOI: 10.1073/pnas.2313010120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/12/2023] [Indexed: 10/27/2023] Open
Abstract
Inter-organelle contact sites between mitochondria and lysosomes mediate the crosstalk and bidirectional regulation of their dynamics in health and disease. However, mitochondria-lysosome contact sites and their misregulation have not been investigated in peripheral sensory neurons. Charcot-Marie-Tooth type 2B disease is an autosomal dominant axonal neuropathy affecting peripheral sensory neurons caused by mutations in the GTPase Rab7. Using live super-resolution and confocal time-lapse microscopy, we showed that mitochondria-lysosome contact sites dynamically form in the soma and axons of peripheral sensory neurons. Interestingly, Charcot-Marie-Tooth type 2B mutant Rab7 led to prolonged mitochondria-lysosome contact site tethering preferentially in the axons of peripheral sensory neurons, due to impaired Rab7 GTP hydrolysis-mediated contact site untethering. We further generated a Charcot-Marie-Tooth type 2B mutant Rab7 knock-in mouse model which exhibited prolonged axonal mitochondria-lysosome contact site tethering and defective downstream axonal mitochondrial dynamics due to impaired Rab7 GTP hydrolysis as well as fragmented mitochondria in the axon of the sciatic nerve. Importantly, mutant Rab7 mice further demonstrated preferential sensory behavioral abnormalities and neuropathy, highlighting an important role for mutant Rab7 in driving degeneration of peripheral sensory neurons. Together, this study identifies an important role for mitochondria-lysosome contact sites in the pathogenesis of peripheral neuropathy.
Collapse
Affiliation(s)
- Yvette C. Wong
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Nirupa D. Jayaraj
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Tayler B. Belton
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - George C. Shum
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Hannah E. Ball
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | - Dongjun Ren
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | | | - Dimitri Krainc
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
- Simpson Querrey Center for Neurogenetics, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| | | | - Daniela M. Menichella
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL60611
| |
Collapse
|
3
|
Wang Y, Troughton LD, Xu F, Chatterjee A, Ding C, Zhao H, Cifuentes LP, Wagner RB, Wang T, Tan S, Chen J, Li L, Umulis D, Kuang S, Suter DM, Yuan C, Chan D, Huang F, Oakes PW, Deng Q. Atypical peripheral actin band formation via overactivation of RhoA and nonmuscle myosin II in mitofusin 2-deficient cells. eLife 2023; 12:e88828. [PMID: 37724949 PMCID: PMC10550287 DOI: 10.7554/elife.88828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 09/19/2023] [Indexed: 09/21/2023] Open
Abstract
Cell spreading and migration play central roles in many physiological and pathophysiological processes. We have previously shown that MFN2 regulates the migration of human neutrophil-like cells via suppressing Rac activation. Here, we show that in mouse embryonic fibroblasts, MFN2 suppresses RhoA activation and supports cell polarization. After initial spreading, the wild-type cells polarize and migrate, whereas the Mfn2-/- cells maintain a circular shape. Increased cytosolic Ca2+ resulting from the loss of Mfn2 is directly responsible for this phenotype, which can be rescued by expressing an artificial tether to bring mitochondria and endoplasmic reticulum to close vicinity. Elevated cytosolic Ca2+ activates Ca2+/calmodulin-dependent protein kinase II, RhoA, and myosin light-chain kinase, causing an overactivation of nonmuscle myosin II, leading to a formation of a prominent F-actin ring at the cell periphery and increased cell contractility. The peripheral actin band alters cell physics and is dependent on substrate rigidity. Our results provide a novel molecular basis to understand how MFN2 regulates distinct signaling pathways in different cells and tissue environments, which is instrumental in understanding and treating MFN2-related diseases.
Collapse
Affiliation(s)
- Yueyang Wang
- Department of Biological Sciences, Purdue University West LafayetteWest LafayetteUnited States
| | - Lee D Troughton
- Cell and Molecular Physiology, Loyola University ChicagoChicagoUnited States
| | - Fan Xu
- Weldon School of Biomedical Engineering, Purdue University West LafayetteWest LafayetteUnited States
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of TechnologyBeijingChina
| | - Aritra Chatterjee
- Weldon School of Biomedical Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - Chang Ding
- Department of Biological Sciences, Purdue University West LafayetteWest LafayetteUnited States
| | - Han Zhao
- Davidson School of Chemical Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - Laura P Cifuentes
- Department of Biological Sciences, Purdue University West LafayetteWest LafayetteUnited States
| | - Ryan B Wagner
- School of Mechanical Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - Tianqi Wang
- Department of Biological Sciences, Purdue University West LafayetteWest LafayetteUnited States
| | - Shelly Tan
- Department of Biological Sciences, Purdue University West LafayetteWest LafayetteUnited States
| | - Jingjuan Chen
- Department of Animal Sciences, Purdue University West LafayetteWest LafayetteUnited States
| | - Linlin Li
- Weldon School of Biomedical Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - David Umulis
- Weldon School of Biomedical Engineering, Purdue University West LafayetteWest LafayetteUnited States
- Department of Agricultural and Biological Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - Shihuan Kuang
- Department of Animal Sciences, Purdue University West LafayetteWest LafayetteUnited States
| | - Daniel M Suter
- Department of Biological Sciences, Purdue University West LafayetteWest LafayetteUnited States
- Purdue Institute for Integrative Neuroscience, Purdue University West LafayetteWest LafayetteUnited States
- Purdue Institute for Inflammation, Immunology & Infectious Disease, Purdue University West LafayetteWest LafayetteUnited States
| | - Chongli Yuan
- Davidson School of Chemical Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - Deva Chan
- Weldon School of Biomedical Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - Fang Huang
- Weldon School of Biomedical Engineering, Purdue University West LafayetteWest LafayetteUnited States
| | - Patrick W Oakes
- Cell and Molecular Physiology, Loyola University ChicagoChicagoUnited States
| | - Qing Deng
- Department of Biological Sciences, Purdue University West LafayetteWest LafayetteUnited States
- Purdue Institute for Inflammation, Immunology & Infectious Disease, Purdue University West LafayetteWest LafayetteUnited States
- Purdue University Center for Cancer Research, Purdue University West LafayetteWest LafayetteUnited States
| |
Collapse
|
4
|
Hines TJ, Bailey J, Liu H, Guntur AR, Seburn KL, Pratt SL, Funke JR, Tarantino LM, Burgess RW. A Novel ENU-Induced Mfn2 Mutation Causes Motor Deficits in Mice without Causing Peripheral Neuropathy. BIOLOGY 2023; 12:953. [PMID: 37508383 PMCID: PMC10376023 DOI: 10.3390/biology12070953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023]
Abstract
Mitochondrial fission and fusion are required for maintaining functional mitochondria. The mitofusins (MFN1 and MFN2) are known for their roles in mediating mitochondrial fusion. Recently, MFN2 has been implicated in other important cellular functions, such as mitophagy, mitochondrial motility, and coordinating endoplasmic reticulum-mitochondria communication. In humans, over 100 MFN2 mutations are associated with a form of inherited peripheral neuropathy, Charcot-Marie-Tooth disease type 2A (CMT2A). Here we describe an ENU-induced mutant mouse line with a recessive neuromuscular phenotype. Behavioral screening showed progressive weight loss and rapid deterioration of motor function beginning at 8 weeks. Mapping and sequencing revealed a missense mutation in exon 18 of Mfn2 (T1928C; Leu643Pro), within the transmembrane domain. Compared to wild-type and heterozygous littermates, Mfn2L643P/L643P mice exhibited diminished rotarod performance and decreases in activity in the open field test, muscular endurance, mean mitochondrial diameter, sensory tests, mitochondrial DNA content, and MFN2 protein levels. However, tests of peripheral nerve physiology and histology were largely normal. Mutant leg bones had reduced cortical bone thickness and bone area fraction. Together, our data indicate that Mfn2L643P causes a recessive motor phenotype with mild bone and mitochondrial defects in mice. Lack of apparent nerve pathology notwithstanding, this is the first reported mouse model with a mutation in the transmembrane domain of the protein, which may be valuable for researchers studying MFN2 biology.
Collapse
Affiliation(s)
| | - Janice Bailey
- Department of Genetics, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Hedi Liu
- Department of Genetics, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Anyonya R Guntur
- Center for Molecular Medicine, Maine Health Institute for Research, Scarborough, ME 04074, USA
| | | | - Samia L Pratt
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Neuroscience Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Jonathan R Funke
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Neuroscience Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Lisa M Tarantino
- Department of Genetics, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert W Burgess
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Neuroscience Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| |
Collapse
|
5
|
Mann JP, Duan X, Patel S, Tábara LC, Scurria F, Alvarez-Guaita A, Haider A, Luijten I, Page M, Protasoni M, Lim K, Virtue S, O'Rahilly S, Armstrong M, Prudent J, Semple RK, Savage DB. A mouse model of human mitofusin-2-related lipodystrophy exhibits adipose-specific mitochondrial stress and reduced leptin secretion. eLife 2023; 12:e82283. [PMID: 36722855 PMCID: PMC9937658 DOI: 10.7554/elife.82283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 01/30/2023] [Indexed: 02/02/2023] Open
Abstract
Mitochondrial dysfunction has been reported in obesity and insulin resistance, but primary genetic mitochondrial dysfunction is generally not associated with these, arguing against a straightforward causal relationship. A rare exception, recently identified in humans, is a syndrome of lower body adipose loss, leptin-deficient severe upper body adipose overgrowth, and insulin resistance caused by the p.Arg707Trp mutation in MFN2, encoding mitofusin 2. How the resulting selective form of mitochondrial dysfunction leads to tissue- and adipose depot-specific growth abnormalities and systemic biochemical perturbation is unknown. To address this, Mfn2R707W/R707W knock-in mice were generated and phenotyped on chow and high fat diets. Electron microscopy revealed adipose-specific mitochondrial morphological abnormalities. Oxidative phosphorylation measured in isolated mitochondria was unperturbed, but the cellular integrated stress response was activated in adipose tissue. Fat mass and distribution, body weight, and systemic glucose and lipid metabolism were unchanged, however serum leptin and adiponectin concentrations, and their secretion from adipose explants were reduced. Pharmacological induction of the integrated stress response in wild-type adipocytes also reduced secretion of leptin and adiponectin, suggesting an explanation for the in vivo findings. These data suggest that the p.Arg707Trp MFN2 mutation selectively perturbs mitochondrial morphology and activates the integrated stress response in adipose tissue. In mice, this does not disrupt most adipocyte functions or systemic metabolism, whereas in humans it is associated with pathological adipose remodelling and metabolic disease. In both species, disproportionate effects on leptin secretion may relate to cell autonomous induction of the integrated stress response.
Collapse
Affiliation(s)
- Jake P Mann
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Xiaowen Duan
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Satish Patel
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Luis Carlos Tábara
- Medical Research Council Mitochondrial Biology Unit, University of CambridgeCambridgeUnited Kingdom
| | - Fabio Scurria
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Anna Alvarez-Guaita
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Afreen Haider
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Ineke Luijten
- Centre for Cardiovascular Science, University of EdinburghEdinburghUnited Kingdom
| | | | - Margherita Protasoni
- Medical Research Council Mitochondrial Biology Unit, University of CambridgeCambridgeUnited Kingdom
| | - Koini Lim
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Sam Virtue
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | - Stephen O'Rahilly
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| | | | - Julien Prudent
- Medical Research Council Mitochondrial Biology Unit, University of CambridgeCambridgeUnited Kingdom
| | - Robert K Semple
- Centre for Cardiovascular Science, University of EdinburghEdinburghUnited Kingdom
- MRC Human Genetics Unit, University of EdinburghEdinburghUnited Kingdom
| | - David B Savage
- Wellcome Trust-MRC Institute of Metabolic Science, University of CambridgeCambridgeUnited Kingdom
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Sharma G, Zaman M, Sabouny R, Joel M, Martens K, Martino D, de Koning AJ, Pfeffer G, Shutt TE. Characterization of a novel variant in the HR1 domain of MFN2 in a patient with ataxia, optic atrophy and sensorineural hearing loss. F1000Res 2022; 10:606. [PMID: 38274408 PMCID: PMC10808857 DOI: 10.12688/f1000research.53230.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/22/2022] [Indexed: 01/27/2024] Open
Abstract
Background: Pathogenic variants in MFN2 cause Charcot-Marie-Tooth disease (CMT) type 2A (CMT2A) and are the leading cause of the axonal subtypes of CMT. CMT2A is characterized by predominantly distal motor weakness and muscle atrophy, with highly variable severity and onset age. Notably, some MFN2 variants can also lead to other phenotypes such as optic atrophy, hearing loss and lipodystrophy. Despite the clear link between MFN2 and CMT2A, our mechanistic understanding of how dysfunction of the MFN2 protein causes human disease pathologies remains incomplete. This lack of understanding is due in part to the multiple cellular roles of MFN2. Though initially characterized for its role in mediating mitochondrial fusion, MFN2 also plays important roles in mediating interactions between mitochondria and other organelles, such as the endoplasmic reticulum and lipid droplets. Additionally, MFN2 is also important for mitochondrial transport, mitochondrial autophagy, and has even been implicated in lipid transfer. Though over 100 pathogenic MFN2 variants have been described to date, only a few have been characterized functionally, and even then, often only for one or two functions. Method: Several MFN2-mediated functions were characterized in fibroblast cells from a patient presenting with cerebellar ataxia, deafness, blindness, and diffuse cerebral and cerebellar atrophy, who harbours a novel homozygous MFN2 variant, D414V, which is found in a region of the HR1 domain of MFN2 where few pathogenic variants occur. Results: We found evidence for impairment of several MFN2-mediated functions. Consistent with reduced mitochondrial fusion, patient fibroblasts exhibited more fragmented mitochondrial networks and had reduced mtDNA copy number. Additionally, patient fibroblasts had reduced oxygen consumption, fewer mitochondrial-ER contacts, and altered lipid droplets that displayed an unusual perinuclear distribution. Conclusion: Overall, this work characterizes D414V as a novel variant in MFN2 and expands the phenotypic presentation of MFN2 variants to include cerebellar ataxia.
Collapse
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, Alberta, T2N 4N1, Canada
| | - Mashiat Zaman
- 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, Alberta, T2N 4N1, Canada
| | - Rasha Sabouny
- 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, Alberta, T2N 4N1, Canada
| | - Matthew Joel
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, University of Calgary, Hotchkiss Brain Institute, Alberta Child Health Research Institute, Calgary, Alberta, T2N 4N1, Canada
| | - Kristina Martens
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, University of Calgary, Hotchkiss Brain Institute, Alberta Child Health Research Institute, Calgary, Alberta, T2N 4N1, Canada
| | - Davide Martino
- Department of Clinical Neurosciences, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - A.P. Jason de Koning
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Gerald Pfeffer
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, University of Calgary, Hotchkiss Brain Institute, Alberta Child Health Research Institute, Calgary, Alberta, 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, Alberta, T2N 4N1, Canada
| |
Collapse
|
8
|
Nguyen‐Le T, Do MD, Le LHG, Nhat QNN, Hoang NTT, Van Le T, Mai TP. Genotype-phenotype characteristics of Vietnamese patients diagnosed with Charcot-Marie-Tooth disease. Brain Behav 2022; 12:e2744. [PMID: 35938991 PMCID: PMC9480926 DOI: 10.1002/brb3.2744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/28/2022] [Accepted: 07/26/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth (CMT) disease is one of the most common hereditary neuropathies. Identifying causative mutations in CMT is essential as it provides important information for genetic diagnosis and counseling. However, genetic information of Vietnamese patients diagnosed with CMT is currently not available. METHODS In this study, we described the clinical profile and determined the mutation spectrum of CMT in a cohort of Vietnamese patients with CMT by using a combination of multiplex ligation-dependent probe amplification and next-generation sequencing targeting 11 genes PMP22, MPZ, EGR2, NEFL, MFN2, GDAP1, GARS, MTMR2, GJB1, RAB7A, LITAF. RESULTS In 31 CMT cases, the mutation detection rate was 42% and the most common genetic aberration was PMP22 duplication. The pedigree analysis showed two de novo mutations c.64C > A (p.P22T) and c.281delG (p.G94Afs*17) in the NEFL and PMP22 genes, respectively. CONCLUSION The results of this study once again emphasize the important role of molecular diagnosis and provide preliminary genetic data on Vietnamese patients with CMT.
Collapse
Affiliation(s)
- Trung‐Hieu Nguyen‐Le
- Faculty of MedicineUniversity of Medicine and Pharmacy at Ho Chi Minh CityVietnam
| | - Minh Duc Do
- Center for Molecular BiomedicineUniversity of Medicine and Pharmacy at Ho Chi Minh CityVietnam
| | - Linh Hoang Gia Le
- Center for Molecular BiomedicineUniversity of Medicine and Pharmacy at Ho Chi Minh CityVietnam
| | - Quynh Nhu Nguyen Nhat
- Center for Molecular BiomedicineUniversity of Medicine and Pharmacy at Ho Chi Minh CityVietnam
| | | | - Tuan Van Le
- Faculty of MedicineUniversity of Medicine and Pharmacy at Ho Chi Minh CityVietnam
| | - Thao Phuong Mai
- Faculty of MedicineUniversity of Medicine and Pharmacy at Ho Chi Minh CityVietnam
| |
Collapse
|
9
|
Cheng XT, Huang N, Sheng ZH. Programming axonal mitochondrial maintenance and bioenergetics in neurodegeneration and regeneration. Neuron 2022; 110:1899-1923. [PMID: 35429433 PMCID: PMC9233091 DOI: 10.1016/j.neuron.2022.03.015] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/04/2022] [Accepted: 03/10/2022] [Indexed: 12/11/2022]
Abstract
Mitochondria generate ATP essential for neuronal growth, function, and regeneration. Due to their polarized structures, neurons face exceptional challenges to deliver mitochondria to and maintain energy homeostasis throughout long axons and terminal branches where energy is in high demand. Chronic mitochondrial dysfunction accompanied by bioenergetic failure is a pathological hallmark of major neurodegenerative diseases. Brain injury triggers acute mitochondrial damage and a local energy crisis that accelerates neuron death. Thus, mitochondrial maintenance defects and axonal energy deficits emerge as central problems in neurodegenerative disorders and brain injury. Recent studies have started to uncover the intrinsic mechanisms that neurons adopt to maintain (or reprogram) axonal mitochondrial density and integrity, and their bioenergetic capacity, upon sensing energy stress. In this review, we discuss recent advances in how neurons maintain a healthy pool of axonal mitochondria, as well as potential therapeutic strategies that target bioenergetic restoration to power neuronal survival, function, and regeneration.
Collapse
Affiliation(s)
- Xiu-Tang Cheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Ning Huang
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA
| | - Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA.
| |
Collapse
|
10
|
Zaman M, Shutt TE. The Role of Impaired Mitochondrial Dynamics in MFN2-Mediated Pathology. Front Cell Dev Biol 2022; 10:858286. [PMID: 35399520 PMCID: PMC8989266 DOI: 10.3389/fcell.2022.858286] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/07/2022] [Indexed: 12/17/2022] Open
Abstract
The Mitofusin 2 protein (MFN2), encoded by the MFN2 gene, was first described for its role in mediating mitochondrial fusion. However, MFN2 is now recognized to play additional roles in mitochondrial autophagy (mitophagy), mitochondrial motility, lipid transfer, and as a tether to other organelles including the endoplasmic reticulum (ER) and lipid droplets. The tethering role of MFN2 is an important mediator of mitochondrial-ER contact sites (MERCs), which themselves have many important functions that regulate mitochondria, including calcium homeostasis and lipid metabolism. Exemplifying the importance of MFN2, pathogenic variants in MFN2 are established to cause the peripheral neuropathy Charcot-Marie-Tooth Disease Subtype 2A (CMT2A). However, the mechanistic basis for disease is not clear. Moreover, additional pathogenic phenotypes such as lipomatosis, distal myopathy, optic atrophy, and hearing loss, can also sometimes be present in patients with CMT2A. Given these variable patient phenotypes, and the many cellular roles played by MFN2, the mechanistic underpinnings of the cellular impairments by which MFN2 dysfunction leads to disease are likely to be complex. Here, we will review what is known about the various functions of MFN2 that are impaired by pathogenic variants causing CMT2A, with a specific emphasis on the ties between MFN2 variants and MERCs.
Collapse
Affiliation(s)
- Mashiat Zaman
- Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute (ACHRI), Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Timothy E. Shutt
- Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute (ACHRI), Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Medical Genetics, University of Calgary, Calgary, AB, Canada
- *Correspondence: Timothy E. Shutt,
| |
Collapse
|
11
|
Mammel AE, Delgado KC, Chin AL, Condon AF, Hill JQ, Aicher SA, Wang Y, Fedorov LM, Robinson FL. Distinct roles for the Charcot-Marie-tooth disease-causing endosomal regulators Mtmr5 and Mtmr13 in axon radial sorting and Schwann cell myelination. Hum Mol Genet 2021; 31:1216-1229. [PMID: 34718573 DOI: 10.1093/hmg/ddab311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 09/29/2021] [Accepted: 10/19/2021] [Indexed: 11/12/2022] Open
Abstract
The form of Charcot-Marie-Tooth type 4B (CMT4B) disease caused by mutations in myotubularin-related 5 (MTMR5; also called SET Binding Factor 1; SBF1) shows a spectrum of axonal and demyelinating nerve phenotypes. This contrasts with the CMT4B subtypes caused by MTMR2 or MTMR13 (SBF2) mutations, which are characterized by myelin outfoldings and classic demyelination. Thus, it is unclear whether MTMR5 plays an analogous or distinct role from that of its homolog, MTMR13, in the peripheral nervous system (PNS). MTMR5 and MTMR13 are pseudophosphatases predicted to regulate endosomal trafficking by activating Rab GTPases and binding to the phosphoinositide 3-phosphatase MTMR2. In the mouse PNS, Mtmr2 was required to maintain wild type levels of Mtmr5 and Mtmr13, suggesting that these factors function in discrete protein complexes. Genetic elimination of both Mtmr5 and Mtmr13 in mice led to perinatal lethality, indicating that the two proteins have partially redundant functions during embryogenesis. Loss of Mtmr5 in mice did not cause CMT4B-like myelin outfoldings. However, adult Mtmr5-/- mouse nerves contained fewer myelinated axons than control nerves, likely as a result of axon radial sorting defects. Consistently, Mtmr5 levels were highest during axon radial sorting and fell sharply after postnatal day seven. Our findings suggest that Mtmr5 and Mtmr13 ensure proper axon radial sorting and Schwann cell myelination, respectively, perhaps through their direct interactions with Mtmr2. This study enhances our understanding of the non-redundant roles of the endosomal regulators MTMR5 and MTMR13 during normal peripheral nerve development and disease.
Collapse
Affiliation(s)
- Anna E Mammel
- The Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.,Cell, Developmental & Cancer Biology Graduate Program, Oregon Health & Science University
| | - Katherine C Delgado
- The Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Andrea L Chin
- The Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Alec F Condon
- The Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.,Neuroscience Graduate Program, Oregon Health & Science University
| | - Jo Q Hill
- Department of Physiology and Pharmacology, Oregon Health & Science University
| | - Sue A Aicher
- Department of Physiology and Pharmacology, Oregon Health & Science University
| | - Yingming Wang
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health & Science University
| | - Lev M Fedorov
- OHSU Transgenic Mouse Models Shared Resource, Knight Cancer Institute, Oregon Health & Science University
| | - Fred L Robinson
- The Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.,Vollum Institute, Oregon Health & Science University
| |
Collapse
|
12
|
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.
Collapse
|
13
|
Animal Models as a Tool to Design Therapeutical Strategies for CMT-like Hereditary Neuropathies. Brain Sci 2021; 11:brainsci11091237. [PMID: 34573256 PMCID: PMC8465478 DOI: 10.3390/brainsci11091237] [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: 07/25/2021] [Revised: 09/05/2021] [Accepted: 09/07/2021] [Indexed: 02/07/2023] Open
Abstract
Since ancient times, animal models have provided fundamental information in medical knowledge. This also applies for discoveries in the field of inherited peripheral neuropathies (IPNs), where they have been instrumental for our understanding of nerve development, pathogenesis of neuropathy, molecules and pathways involved and to design potential therapies. In this review, we briefly describe how animal models have been used in ancient medicine until the use of rodents as the prevalent model in present times. We then travel along different examples of how rodents have been used to improve our understanding of IPNs. We do not intend to describe all discoveries and animal models developed for IPNs, but just to touch on a few arbitrary and paradigmatic examples, taken from our direct experience or from literature. The idea is to show how strategies have been developed to finally arrive to possible treatments for IPNs.
Collapse
|
14
|
Sharma G, Sabouny R, Joel M, Martens K, Martino D, de Koning AJ, Pfeffer G, Shutt TE. Characterization of a novel variant in the HR1 domain of MFN2 in a patient with ataxia, optic atrophy and sensorineural hearing loss. F1000Res 2021. [DOI: 10.12688/f1000research.53230.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Background: Pathogenic variants in MFN2 cause Charcot-Marie-Tooth disease (CMT) type 2A (CMT2A) and are the leading cause of the axonal subtypes of CMT. CMT2A is characterized by predominantly distal motor weakness and muscle atrophy, with highly variable severity and onset age. Notably, some MFN2 variants can also lead to other phenotypes such as optic atrophy, hearing loss and lipodystrophy. Despite the clear link between MFN2 and CMT2A, our mechanistic understanding of how dysfunction of the MFN2 protein causes human disease pathologies remains incomplete. This lack of understanding is due in part to the multiple cellular roles of MFN2. Though initially characterized for its role in mediating mitochondrial fusion, MFN2 also plays important roles in mediating interactions between mitochondria and other organelles, such as the endoplasmic reticulum and lipid droplets. Additionally, MFN2 is also important for mitochondrial transport, mitochondrial autophagy, and has even been implicated in lipid transfer. Though over 100 pathogenic MFN2 variants have been described to date, only a few have been characterized functionally, and even then, often only for one or two functions. Method: Several MFN2-mediated functions were characterized in fibroblast cells from a patient presenting with cerebellar ataxia, deafness, blindness, and diffuse cerebral and cerebellar atrophy, who harbours a novel homozygous MFN2 variant, D414V, which is found in a region of the HR1 domain of MFN2 where few pathogenic variants occur. Results: We found evidence for impairment of several MFN2-mediated functions. Consistent with reduced mitochondrial fusion, patient fibroblasts exhibited more fragmented mitochondrial networks and had reduced mtDNA copy number. Additionally, patient fibroblasts had reduced oxygen consumption, fewer mitochondrial-ER contacts, and altered lipid droplets that displayed an unusual perinuclear distribution. Conclusion: Overall, this work characterizes D414V as a novel variant in MFN2 and expands the phenotypic presentation of MFN2 variants to include cerebellar ataxia.
Collapse
|
15
|
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.
Collapse
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;
| |
Collapse
|
16
|
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.
Collapse
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
| | | |
Collapse
|
17
|
Genetic mechanisms of peripheral nerve disease. Neurosci Lett 2020; 742:135357. [PMID: 33249104 DOI: 10.1016/j.neulet.2020.135357] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/24/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022]
Abstract
Peripheral neuropathies of genetic etiology are a very diverse group of disorders manifesting either as non-syndromic inherited neuropathies without significant manifestations outside the peripheral nervous system, or as part of a systemic or syndromic genetic disorder. The former and most frequent group is collectively known as Charcot-Marie-Tooth disease (CMT), with prevalence as high as 1:2,500 world-wide, and has proven to be genetically highly heterogeneous. More than 100 different genes have been identified so far to cause various CMT forms, following all possible inheritance patterns. CMT causative genes belong to several common functional pathways that are essential for the integrity of the peripheral nerve. Their discovery has provided insights into the normal biology of axons and myelinating cells, and has highlighted the molecular mechanisms including both loss of function and gain of function effects, leading to peripheral nerve degeneration. Demyelinating neuropathies result from dysfunction of genes primarily affecting myelinating Schwann cells, while axonal neuropathies are caused by genes affecting mostly neurons and their long axons. Furthermore, mutation in genes expressed outside the nervous system, as in the case of inherited amyloid neuropathies, may cause peripheral neuropathy resulting from accumulation of β-structured amyloid fibrils in peripheral nerves in addition to various organs. Increasing insights into the molecular-genetic mechanisms have revealed potential therapeutic targets. These will enable the development of novel therapeutics for genetic neuropathies that remain, in their majority, without effective treatment.
Collapse
|
18
|
Sullivan JM, Motley WW, Johnson JO, Aisenberg WH, Marshall KL, Barwick KE, Kong L, Huh JS, Saavedra-Rivera PC, McEntagart MM, Marion MH, Hicklin LA, Modarres H, Baple EL, Farah MH, Zuberi AR, Lutz CM, Gaudet R, Traynor BJ, Crosby AH, Sumner CJ. Dominant mutations of the Notch ligand Jagged1 cause peripheral neuropathy. J Clin Invest 2020; 130:1506-1512. [PMID: 32065591 DOI: 10.1172/jci128152] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 12/12/2019] [Indexed: 12/23/2022] Open
Abstract
Notch signaling is a highly conserved intercellular pathway with tightly regulated and pleiotropic roles in normal tissue development and homeostasis. Dysregulated Notch signaling has also been implicated in human disease, including multiple forms of cancer, and represents an emerging therapeutic target. Successful development of such therapeutics requires a detailed understanding of potential on-target toxicities. Here, we identify autosomal dominant mutations of the canonical Notch ligand Jagged1 (or JAG1) as a cause of peripheral nerve disease in 2 unrelated families with the hereditary axonal neuropathy Charcot-Marie-Tooth disease type 2 (CMT2). Affected individuals in both families exhibited severe vocal fold paresis, a rare feature of peripheral nerve disease that can be life-threatening. Our studies of mutant protein posttranslational modification and localization indicated that the mutations (p.Ser577Arg, p.Ser650Pro) impair protein glycosylation and reduce JAG1 cell surface expression. Mice harboring heterozygous CMT2-associated mutations exhibited mild peripheral neuropathy, and homozygous expression resulted in embryonic lethality by midgestation. Together, our findings highlight a critical role for JAG1 in maintaining peripheral nerve integrity, particularly in the recurrent laryngeal nerve, and provide a basis for the evaluation of peripheral neuropathy as part of the clinical development of Notch pathway-modulating therapeutics.
Collapse
Affiliation(s)
- Jeremy M Sullivan
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - William W Motley
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Janel O Johnson
- Laboratory of Neurogenetics, National Institute on Aging, NIH, Bethesda, Maryland, USA
| | - William H Aisenberg
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Katherine L Marshall
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Katy Es Barwick
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, United Kingdom
| | - Lingling Kong
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jennifer S Huh
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Meriel M McEntagart
- Medical Genetics, Clinical Developmental Sciences, St. George's University of London, London, United Kingdom
| | | | - Lucy A Hicklin
- Department of Ears, Nose and Throat (ENT), St. George's Hospital, London, United Kingdom
| | | | - Emma L Baple
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, United Kingdom
| | - Mohamed H Farah
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Aamir R Zuberi
- Genetic Resource Science, The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Cathleen M Lutz
- Genetic Resource Science, The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Rachelle Gaudet
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Bryan J Traynor
- Laboratory of Neurogenetics, National Institute on Aging, NIH, Bethesda, Maryland, USA.,Brain Sciences Institute, Department of Neurology, Johns Hopkins Hospital, Baltimore, Maryland, USA
| | - Andrew H Crosby
- RILD Wellcome Wolfson Centre, Royal Devon and Exeter NHS Foundation Trust, Exeter, Devon, United Kingdom
| | - Charlotte J Sumner
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| |
Collapse
|
19
|
Dorn GW. Mitofusin 2 Dysfunction and Disease in Mice and Men. Front Physiol 2020; 11:782. [PMID: 32733278 PMCID: PMC7363930 DOI: 10.3389/fphys.2020.00782] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 06/15/2020] [Indexed: 01/30/2023] Open
Abstract
A causal relationship between Mitofusin (MFN) 2 gene mutations and the hereditary axonal neuropathy Charcot-Marie-Tooth disease type 2A (CMT2A) was described over 15 years ago. During the intervening period much has been learned about MFN2 functioning in mitochondrial fusion, calcium signaling, and quality control, and the consequences of these MFN2 activities on cell metabolism, fitness, and development. Nevertheless, the challenge of defining the central underlying mechanism(s) linking mitochondrial abnormalities to progressive dying-back of peripheral arm and leg nerves in CMT2A is largely unmet. Here, a different perspective of why, in humans, MFN2 dysfunction preferentially impacts peripheral nerves is provided based on recent insights into its role in determining whether individual mitochondria will be fusion-competent and retained within the cell, or are fusion-impaired, sequestered, and eliminated by mitophagy. Evidence for and against a regulatory role of mitofusins in mitochondrial transport is reviewed, nagging questions defined, and implications on mitochondrial fusion, quality control, and neuronal degeneration discussed. Finally, in the context of recently described mitofusin activating peptides and small molecules, an overview is provided of potential therapeutic applications for pharmacological enhancement of mitochondrial fusion and motility in CMT2A and other neurodegenerative conditions.
Collapse
Affiliation(s)
- Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
| |
Collapse
|
20
|
Soh MS, Cheng X, Vijayaraghavan T, Vernon A, Liu J, Neumann B. Disruption of genes associated with Charcot-Marie-Tooth type 2 lead to common behavioural, cellular and molecular defects in Caenorhabditis elegans. PLoS One 2020; 15:e0231600. [PMID: 32294113 PMCID: PMC7159224 DOI: 10.1371/journal.pone.0231600] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 03/26/2020] [Indexed: 11/23/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is an inherited peripheral motor and sensory neuropathy. The disease is divided into demyelinating (CMT1) and axonal (CMT2) neuropathies, and although we have gained molecular information into the details of CMT1 pathology, much less is known about CMT2. Due to its clinical and genetic heterogeneity, coupled with a lack of animal models, common underlying mechanisms remain elusive. In order to gain an understanding of the normal function of genes associated with CMT2, and to draw direct comparisons between them, we have studied the behavioural, cellular and molecular consequences of mutating nine different genes in the nematode Caenorhabditis elegans (lin-41/TRIM2, dyn-1/DNM2, unc-116/KIF5A, fzo-1/MFN2, osm-9/TRPV4, cua-1/ATP7A, hsp-25/HSPB1, hint-1/HINT1, nep-2/MME). We show that C. elegans defective for these genes display debilitated movement in crawling and swimming assays. Severe morphological defects in cholinergic motors neurons are also evident in two of the mutants (dyn-1 and unc-116). Furthermore, we establish methods for quantifying muscle morphology and use these to demonstrate that loss of muscle structure occurs in the majority of mutants studied. Finally, using electrophysiological recordings of neuromuscular junction (NMJ) activity, we uncover reductions in spontaneous postsynaptic current frequency in lin-41, dyn-1, unc-116 and fzo-1 mutants. By comparing the consequences of mutating numerous CMT2-related genes, this study reveals common deficits in muscle structure and function, as well as NMJ signalling when these genes are disrupted.
Collapse
Affiliation(s)
- Ming S. Soh
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| | - Xinran Cheng
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| | - Tarika Vijayaraghavan
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| | - Arwen Vernon
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| | - Jie Liu
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| | - Brent Neumann
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Anatomy and Developmental Biology, Monash University, Melbourne, VIC, Australia
| |
Collapse
|
21
|
Ballard A, Zeng R, Zarei A, Shao C, Cox L, Yan H, Franco A, Dorn GW, Faccio R, Veis DJ. The tethering function of mitofusin2 controls osteoclast differentiation by modulating the Ca 2+-NFATc1 axis. J Biol Chem 2020; 295:6629-6640. [PMID: 32165499 DOI: 10.1074/jbc.ra119.012023] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/06/2020] [Indexed: 12/16/2022] Open
Abstract
Dynamic regulation of the mitochondrial network by mitofusins (MFNs) modulates energy production, cell survival, and many intracellular signaling events, including calcium handling. However, the relative importance of specific mitochondrial functions and their dependence on MFNs vary greatly among cell types. Osteoclasts have many mitochondria, and increased mitochondrial biogenesis and oxidative phosphorylation enhance bone resorption, but little is known about the mitochondrial network or MFNs in osteoclasts. Because expression of each MFN isoform increases with osteoclastogenesis, we conditionally deleted MFN1 and MFN2 (double conditional KO (dcKO)) in murine osteoclast precursors, finding that this increased bone mass in young female mice and abolished osteoclast precursor differentiation into mature osteoclasts in vitro Defective osteoclastogenesis was reversed by overexpression of MFN2 but not MFN1; therefore, we generated mice lacking only MFN2 in osteoclasts. MFN2-deficient female mice had increased bone mass at 1 year and resistance to Receptor Activator of NF-κB Ligand (RANKL)-induced osteolysis at 8 weeks. To explore whether MFN-mediated tethering or mitophagy is important for osteoclastogenesis, we overexpressed MFN2 variants defective in either function in dcKO precursors and found that, although mitophagy was dispensable for differentiation, tethering was required. Because the master osteoclastogenic transcriptional regulator nuclear factor of activated T cells 1 (NFATc1) is calcium-regulated, we assessed calcium release from the endoplasmic reticulum and store-operated calcium entry and found that the latter was blunted in dcKO cells. Restored osteoclast differentiation by expression of intact MFN2 or the mitophagy-defective variant was associated with normalization of store-operated calcium entry and NFATc1 levels, indicating that MFN2 controls mitochondrion-endoplasmic reticulum tethering in osteoclasts.
Collapse
Affiliation(s)
- Anna Ballard
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Rong Zeng
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Allahdad Zarei
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Christine Shao
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Linda Cox
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Hui Yan
- Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110.,Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.,Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Antonietta Franco
- Center for Pharmacogenomics, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Gerald W Dorn
- Center for Pharmacogenomics, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Roberta Faccio
- Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110.,Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.,Shriners Hospitals for Children, St. Louis, Missouri 63110
| | - Deborah J Veis
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 .,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110.,Shriners Hospitals for Children, St. Louis, Missouri 63110.,Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
| |
Collapse
|
22
|
Chan DC. Mitochondrial Dynamics and Its Involvement in Disease. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2019; 15:235-259. [PMID: 31585519 DOI: 10.1146/annurev-pathmechdis-012419-032711] [Citation(s) in RCA: 613] [Impact Index Per Article: 122.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The dynamic properties of mitochondria-including their fusion, fission, and degradation-are critical for their optimal function in energy generation. The interplay of fusion and fission confers widespread benefits on mitochondria, including efficient transport, increased homogenization of the mitochondrial population, and efficient oxidative phosphorylation. These benefits arise through control of morphology, content exchange, equitable inheritance of mitochondria, maintenance of high-quality mitochondrial DNA, and segregation of damaged mitochondria for degradation. The key components of the machinery mediating mitochondrial fusion and fission belong to the dynamin family of GTPases that utilize GTP hydrolysis to drive mechanical work on biological membranes. Defects in this machinery cause a range of diseases that especially affect the nervous system. In addition, several common diseases, including neurodegenerative diseases and cancer, strongly affect mitochondrial dynamics.
Collapse
Affiliation(s)
- David C Chan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA;
| |
Collapse
|
23
|
Rebelo AP, Saade D, Pereira CV, Farooq A, Huff TC, Abreu L, Moraes CT, Mnatsakanova D, Mathews K, Yang H, Schon EA, Zuchner S, Shy ME. SCO2 mutations cause early-onset axonal Charcot-Marie-Tooth disease associated with cellular copper deficiency. Brain 2019; 141:662-672. [PMID: 29351582 DOI: 10.1093/brain/awx369] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/14/2017] [Indexed: 01/06/2023] Open
Abstract
Recessive mutations in the mitochondrial copper-binding protein SCO2, cytochrome c oxidase (COX) assembly protein, have been reported in several cases with fatal infantile cardioencephalomyopathy with COX deficiency. Significantly expanding the known phenotypic spectrum, we identified compound heterozygous variants in SCO2 in two unrelated patients with axonal polyneuropathy, also known as Charcot-Marie-Tooth disease type 4. Different from previously described cases, our patients developed predominantly motor neuropathy, they survived infancy, and they have not yet developed the cardiomyopathy that causes death in early infancy in reported patients. Both of our patients harbour missense mutations near the conserved copper-binding motif (CXXXC), including the common pathogenic variant E140K and a novel change D135G. In addition, each patient carries a second mutation located at the same loop region, resulting in compound heterozygote changes E140K/P169T and D135G/R171Q. Patient fibroblasts showed reduced levels of SCO2, decreased copper levels and COX deficiency. Given that another Charcot-Marie-Tooth disease gene, ATP7A, is a known copper transporter, our findings further underline the relevance of copper metabolism in Charcot-Marie-Tooth disease.
Collapse
Affiliation(s)
- Adriana P Rebelo
- 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, USA
| | - Dimah Saade
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, USA
| | | | - Amjad Farooq
- Biochemistry Department, University of Miami Miller School of Medicine, Miami, USA
| | - Tyler C Huff
- Department of Neurology, University of Miami, Miami, USA
| | - Lisa Abreu
- 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, USA
| | | | - Diana Mnatsakanova
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, USA
| | - Kathy Mathews
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, USA
| | - Hua Yang
- Department of Neurology, Columbia University Medical Center, New York, USA
| | - Eric A Schon
- Department of Neurology, Columbia University Medical Center, New York, USA.,Department of Genetics and Development, Columbia University Medical Center, New York, USA
| | - Stephan Zuchner
- 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, USA
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, USA
| |
Collapse
|
24
|
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.
Collapse
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
| |
Collapse
|
25
|
Altered interplay between endoplasmic reticulum and mitochondria in Charcot-Marie-Tooth type 2A neuropathy. Proc Natl Acad Sci U S A 2019; 116:2328-2337. [PMID: 30659145 DOI: 10.1073/pnas.1810932116] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mutations in the MFN2 gene encoding Mitofusin 2 lead to the development of Charcot-Marie-Tooth type 2A (CMT2A), a dominant axonal form of peripheral neuropathy. Mitofusin 2 is localized at both the outer membrane of mitochondria and the endoplasmic reticulum and is particularly enriched at specialized contact regions known as mitochondria-associated membranes (MAM). We observed that expression of MFN2R94Q induces distal axonal degeneration in the absence of overt neuronal death. The presence of mutant protein leads to reduction in endoplasmic reticulum and mitochondria contacts in CMT2A patient-derived fibroblasts, in primary neurons and in vivo, in motoneurons of a mouse model of CMT2A. These changes are concomitant with endoplasmic reticulum stress, calcium handling defects, and changes in the geometry and axonal transport of mitochondria. Importantly, pharmacological treatments reinforcing endoplasmic reticulum-mitochondria cross-talk, or reducing endoplasmic reticulum stress, restore the mitochondria morphology and prevent axonal degeneration. These results highlight defects in MAM as a cellular mechanism contributing to CMT2A pathology mediated by mutated MFN2.
Collapse
|
26
|
Acquired Expression of Mutant Mitofusin 2 Causes Progressive Neurodegeneration and Abnormal Behavior. J Neurosci 2019; 39:1588-1604. [PMID: 30606759 DOI: 10.1523/jneurosci.2139-18.2018] [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: 08/20/2018] [Revised: 12/03/2018] [Accepted: 12/17/2018] [Indexed: 12/17/2022] Open
Abstract
Neurons have high plasticity in developmental and juvenile stages that decreases in adulthood. Mitochondrial dynamics are highly important in neurons to maintain normal function. To compare dependency on mitochondrial dynamics in juvenile and adult stages, we generated a mouse model capable of selective timing of the expression of a mutant of the mitochondrial fusion factor Mitofusin 2 (MFN2). Mutant expression in the juvenile stage had lethal effects. Contrastingly, abnormalities did not manifest until 150 d after mutant expression during adulthood. After this silent 150 d period, progressive neurodegeneration, abnormal behaviors, and learning and memory deficits similar to those seen in human neurodegenerative diseases were observed. This indicates that abnormal neuronal mitochondrial dynamics seriously affect survival during early life stages and can also significantly damage brain function after maturation. Our findings highlight the need to consider the timing of disease onset in mimicking human neurodegenerative diseases.SIGNIFICANCE STATEMENT To compare the dependency on mitochondrial dynamics in neurons in juvenile and adult stages, we generated a mouse model expressing a mutant of the mitochondrial fusion factor MFN2 in an arbitrary timing. Juvenile expression of the mutant showed acute and severe phenotypes and had lethal effects; however, post-adult expression induced delayed but progressive phenotypes resembling those found in human neurodegenerative diseases. Our results indicate that abnormal neuronal mitochondrial dynamics seriously affect survival during early life stages and can also significantly damage brain function after maturation. This strongly suggests that the timing of expression should be considered when establishing an animal model that closely resembles human neurodegenerative diseases.
Collapse
|
27
|
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.
Collapse
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
| |
Collapse
|
28
|
Eisner V, Picard M, Hajnóczky G. Mitochondrial dynamics in adaptive and maladaptive cellular stress responses. Nat Cell Biol 2018; 20:755-765. [PMID: 29950571 PMCID: PMC6716149 DOI: 10.1038/s41556-018-0133-0] [Citation(s) in RCA: 361] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 05/29/2018] [Indexed: 12/22/2022]
Abstract
Mitochondria sense and respond to many stressors and can support either cell survival or death through energy production and signaling pathways. Mitochondrial responses depend on fusion-fission dynamics that dilute and segregate damaged mitochondria. Mitochondrial motility and inter-organellar interactions, including with the endoplasmic reticulum, also function in cellular adaptation to stress. In this Review, we discuss how stressors influence these components, and how they contribute to the complex adaptive and pathological responses that lead to disease.
Collapse
Affiliation(s)
- Verónica Eisner
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Martin Picard
- Division of Behavioral Medicine, Departments of Psychiatry and Neurology, The Merritt Center, Columbia Translational Neuroscience Initiative, Columbia Aging Center, Columbia University Medical Center, New York, NY, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.
| |
Collapse
|
29
|
Lancaster E, Li J, Hanania T, Liem R, Scheideler MA, Scherer SS. Myelinated axons fail to develop properly in a genetically authentic mouse model of Charcot-Marie-Tooth disease type 2E. Exp Neurol 2018; 308:13-25. [PMID: 29940160 DOI: 10.1016/j.expneurol.2018.06.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 06/14/2018] [Accepted: 06/19/2018] [Indexed: 11/25/2022]
Abstract
We have analyzed a mouse model of Charcot-Marie-Tooth disease 2E (CMT2E) harboring a heterozygous p.Asn98Ser (p.N98S) Nefl mutation, whose human counterpart results in a severe, early-onset neuropathy. Behavioral, electrophysiological, and pathological analyses were done on separate cohorts of NeflN98S/+ mutant mice and their wild type Nefl+/+ littermates between 8 and 48 weeks of age. The motor performance of NeflN98S/+ mice, as evidenced by altered balance and gait measures, was impaired at every age examined (from 6 to 25 weeks of age). At all times examined, myelinated axons were smaller and contained markedly fewer neurofilaments in NeflN98S/+ mice, in all examined aspects of the PNS, from the nerve roots to the distal ends of the sciatic and caudal nerves. Similarly, the myelinated axons in the various tracts of the spinal cord and in the optic nerves were smaller and contained fewer neurofilaments in mutant mice. The myelinated axons in both the PNS and the CNS of mutant mice had relatively thicker myelin sheaths. The amplitude and the nerve conduction velocity of the caudal nerves were reduced in proportion with the diminished sizes of myelinated axons. Conspicuous aggregations of neurofilaments were only seen in primary sensory and motor neurons, and were largely confined to the cell bodies and proximal axons. There was evidence of axonal degeneration and regeneration of myelinated axons, mostly in distal nerves. In summary, the p.N98S mutation causes a profound reduction of neurofilaments in the myelinated axons of the PNS and CNS, resulting in substantially reduced axonal diameters, particularly of large myelinated axons, and distal axon loss in the PNS.
Collapse
Affiliation(s)
- Eunjoo Lancaster
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Jian Li
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Taleen Hanania
- Psychogenics Inc 215 College Road Paramus, NJ 07652, United States
| | - Ronald Liem
- Department of Pathology, Columbia University College of Physicians & Surgeons, New York, NY 10032, United States
| | | | - Steven S Scherer
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
| |
Collapse
|
30
|
Mitofusin 2: from functions to disease. Cell Death Dis 2018; 9:330. [PMID: 29491355 PMCID: PMC5832425 DOI: 10.1038/s41419-017-0023-6] [Citation(s) in RCA: 209] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 02/07/2023]
Abstract
Mitochondria are highly dynamic organelles whose functions are essential for cell viability. Within the cell, the mitochondrial network is continuously remodeled through the balance between fusion and fission events. Moreover, it dynamically contacts other organelles, particularly the endoplasmic reticulum, with which it enterprises an important functional relationship able to modulate several cellular pathways. Being mitochondria key bioenergetics organelles, they have to be transported to all the specific high-energy demanding sites within the cell and, when damaged, they have to be efficiently removed. Among other proteins, Mitofusin 2 represents a key player in all these mitochondrial activities (fusion, trafficking, turnover, contacts with other organelles), the balance of which results in the appropriate mitochondrial shape, function, and distribution within the cell. Here we review the structural and functional properties of Mitofusin 2, highlighting its crucial role in several cell pathways, as well as in the pathogenesis of neurodegenerative diseases, metabolic disorders, cardiomyopathies, and cancer.
Collapse
|
31
|
Endoplasmic reticulum and mitochondria in diseases of motor and sensory neurons: a broken relationship? Cell Death Dis 2018; 9:333. [PMID: 29491369 PMCID: PMC5832431 DOI: 10.1038/s41419-017-0125-1] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Revised: 09/25/2017] [Accepted: 10/10/2017] [Indexed: 12/13/2022]
Abstract
Recent progress in the understanding of neurodegenerative diseases revealed that multiple molecular mechanisms contribute to pathological changes in neurons. A large fraction of these alterations can be linked to dysfunction in the endoplasmic reticulum (ER) and mitochondria, affecting metabolism and secretion of lipids and proteins, calcium homeostasis, and energy production. Remarkably, these organelles are interacting with each other at specialized domains on the ER called mitochondria-associated membranes (MAMs). These membrane structures rely on the interaction of several complexes of proteins localized either at the mitochondria or at the ER interface and serve as an exchange platform of calcium, metabolites, and lipids, which are critical for the function of both organelles. In addition, recent evidence indicates that MAMs also play a role in the control of mitochondria dynamics and autophagy. MAMs thus start to emerge as a key element connecting many changes observed in neurodegenerative diseases. This review will focus on the role of MAMs in amyotrophic lateral sclerosis (ALS) and hereditary motor and sensory neuropathy, two neurodegenerative diseases particularly affecting neurons with long projecting axons. We will discuss how defects in MAM signaling may impair neuronal calcium homeostasis, mitochondrial dynamics, ER function, and autophagy, leading eventually to axonal degeneration. The possible impact of MAM dysfunction in glial cells, which may affect the capacity to support neurons and/or axons, will also be described. Finally, the possible role of MAMs as an interesting target for development of therapeutic interventions aiming at delaying or preventing neurodegeneration will be highlighted.
Collapse
|
32
|
Kalmar B, Innes A, Wanisch K, Kolaszynska AK, Pandraud A, Kelly G, Abramov AY, Reilly MM, Schiavo G, Greensmith L. Mitochondrial deficits and abnormal mitochondrial retrograde axonal transport play a role in the pathogenesis of mutant Hsp27-induced Charcot Marie Tooth Disease. Hum Mol Genet 2018; 26:3313-3326. [PMID: 28595321 PMCID: PMC5808738 DOI: 10.1093/hmg/ddx216] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 05/25/2017] [Indexed: 11/26/2022] Open
Abstract
Mutations in the small heat shock protein Hsp27, encoded by the HSPB1 gene, have been shown to cause Charcot Marie Tooth Disease type 2 (CMT-2) or distal hereditary motor neuropathy (dHMN). Protein aggregation and axonal transport deficits have been implicated in the disease. In this study, we conducted analysis of bidirectional movements of mitochondria in primary motor neuron axons expressing wild type and mutant Hsp27. We found significantly slower retrograde transport of mitochondria in Ser135Phe, Pro39Leu and Arg140Gly mutant Hsp27 expressing motor neurons than in wild type Hsp27 neurons, although anterograde movement velocities remained normal. Retrograde transport of other important cargoes, such as the p75 neurotrophic factor receptor was minimally altered in mutant Hsp27 neurons, implicating that axonal transport deficits primarily affect mitochondria and the axonal transport machinery itself is less affected. Investigation of mitochondrial function revealed a decrease in mitochondrial membrane potential in mutant Hsp27 expressing motor axons, as well as a reduction in mitochondrial complex 1 activity, increased vulnerability of mitochondria to mitochondrial stressors, leading to elevated superoxide release and reduced mitochondrial glutathione (GSH) levels, although cytosolic GSH remained normal. This mitochondrial redox imbalance in mutant Hsp27 motor neurons is likely to cause low level of oxidative stress, which in turn will contribute to, and indeed may be the underlying cause of the deficits in mitochondrial axonal transport. Together, these findings suggest that the mitochondrial abnormalities in mutant Hsp27-induced neuropathies may be a primary cause of pathology, leading to further deficits in the mitochondrial axonal transport and onset of disease.
Collapse
Affiliation(s)
| | - Amy Innes
- Sobell Department of Motor Neuroscience and Movement Disorders.,MRC Centre for Neuromuscular Diseases
| | - Klaus Wanisch
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK
| | | | - Amelie Pandraud
- MRC Centre for Neuromuscular Diseases.,Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK
| | - Gavin Kelly
- Bioinformatics and Biostatistics Science Technology Platform, The Francis Crick Institute, London NW1?1AT, UK
| | | | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases.,Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square House, Queen Square, London WC1N 3BG, UK
| | | | - Linda Greensmith
- Sobell Department of Motor Neuroscience and Movement Disorders.,MRC Centre for Neuromuscular Diseases
| |
Collapse
|
33
|
Yamaguchi M, Takashima H. Drosophila Charcot-Marie-Tooth Disease Models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1076:97-117. [PMID: 29951817 DOI: 10.1007/978-981-13-0529-0_7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) was initially described in 1886. It is characterized by defects in the peripheral nervous system, including sensory and motor neurons. Although more than 80 CMT-causing genes have been identified to date, an effective therapy has not yet been developed for this disease. Since Drosophila does not have axons surrounded by myelin sheaths or Schwann cells, the establishment of a demyelinating CMT model is not appropriate. In this chapter, after overviewing CMT, examples of Drosophila CMT models with axonal neuropathy and other animal CMT models are described.
Collapse
Affiliation(s)
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| |
Collapse
|
34
|
Common and Divergent Mechanisms in Developmental Neuronal Remodeling and Dying Back Neurodegeneration. Curr Biol 2017; 26:R628-R639. [PMID: 27404258 DOI: 10.1016/j.cub.2016.05.025] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cell death is an inherent process that is required for the proper wiring of the nervous system. Studies over the last four decades have shown that, in a parallel developmental pathway, axons and dendrites are eliminated without the death of the neuron. This developmentally regulated 'axonal death' results in neuronal remodeling, which is an essential mechanism to sculpt neuronal networks in both vertebrates and invertebrates. Studies across various organisms have demonstrated that a conserved strategy in the formation of adult neuronal circuitry often involves generating too many connections, most of which are later eliminated with high temporal and spatial resolution. Can neuronal remodeling be regarded as developmentally and spatially regulated neurodegeneration? It has been previously speculated that injury-induced degeneration (Wallerian degeneration) shares some molecular features with 'dying back' neurodegenerative diseases. In this opinion piece, we examine the similarities and differences between the mechanisms regulating neuronal remodeling and those being perturbed in dying back neurodegenerative diseases. We focus primarily on amyotrophic lateral sclerosis and peripheral neuropathies and highlight possible shared pathways and mechanisms. While mechanistic data are only just beginning to emerge, and despite the inherent differences between disease-oriented and developmental processes, we believe that some of the similarities between these developmental and disease-initiated degeneration processes warrant closer collaborations and crosstalk between these different fields.
Collapse
|
35
|
Rocha N, Bulger DA, Frontini A, Titheradge H, Gribsholt SB, Knox R, Page M, Harris J, Payne F, Adams C, Sleigh A, Crawford J, Gjesing AP, Bork-Jensen J, Pedersen O, Barroso I, Hansen T, Cox H, Reilly M, Rossor A, Brown RJ, Taylor SI, McHale D, Armstrong M, Oral EA, Saudek V, O'Rahilly S, Maher ER, Richelsen B, Savage DB, Semple RK. Human biallelic MFN2 mutations induce mitochondrial dysfunction, upper body adipose hyperplasia, and suppression of leptin expression. eLife 2017; 6:e23813. [PMID: 28414270 PMCID: PMC5422073 DOI: 10.7554/elife.23813] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 04/11/2017] [Indexed: 12/25/2022] Open
Abstract
MFN2 encodes mitofusin 2, a membrane-bound mediator of mitochondrial membrane fusion and inter-organelle communication. MFN2 mutations cause axonal neuropathy, with associated lipodystrophy only occasionally noted, however homozygosity for the p.Arg707Trp mutation was recently associated with upper body adipose overgrowth. We describe similar massive adipose overgrowth with suppressed leptin expression in four further patients with biallelic MFN2 mutations and at least one p.Arg707Trp allele. Overgrown tissue was composed of normal-sized, UCP1-negative unilocular adipocytes, with mitochondrial network fragmentation, disorganised cristae, and increased autophagosomes. There was strong transcriptional evidence of mitochondrial stress signalling, increased protein synthesis, and suppression of signatures of cell death in affected tissue, whereas mitochondrial morphology and gene expression were normal in skin fibroblasts. These findings suggest that specific MFN2 mutations cause tissue-selective mitochondrial dysfunction with increased adipocyte proliferation and survival, confirm a novel form of excess adiposity with paradoxical suppression of leptin expression, and suggest potential targeted therapies.
Collapse
Affiliation(s)
- Nuno Rocha
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - David A Bulger
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Andrea Frontini
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
| | - Hannah Titheradge
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
- West Midlands Medical Genetics Department, Birmingham Women's Hospital, Edgbaston, Birmingham, United Kingdom
| | - Sigrid Bjerge Gribsholt
- Department of Endocrinology and Internal Medicine and Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
| | - Rachel Knox
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Matthew Page
- New Medicines, UCB Pharma, Slough, United Kingdom
| | - Julie Harris
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Felicity Payne
- Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Claire Adams
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Alison Sleigh
- Wolfson Brain Imaging Centre, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, United Kingdom
- National Institute for Health Research/Wellcome Trust Clinical Research Facility, Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - John Crawford
- Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Anette Prior Gjesing
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jette Bork-Jensen
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Oluf Pedersen
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Inês Barroso
- Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Torben Hansen
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Helen Cox
- West Midlands Medical Genetics Department, Birmingham Women's Hospital, Edgbaston, Birmingham, United Kingdom
| | - Mary Reilly
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, United Kingdom
| | - Alex Rossor
- MRC Centre for Neuromuscular Diseases, National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, London, United Kingdom
| | - Rebecca J Brown
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, United States
| | - Simeon I Taylor
- University of Maryland School of Medicine, Baltimore, United States
| | | | | | - Elif A Oral
- Metabolism, Endocrinology and Diabetes (MEND) Division, Department of Internal of Medicine, Brehm Center for Diabetes, Ann Arbor, United States
| | - Vladimir Saudek
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Stephen O'Rahilly
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Eamonn R Maher
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
- Department of Medical Genetics, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
| | - Bjørn Richelsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital and Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - David B Savage
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Robert K Semple
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| |
Collapse
|
36
|
Bannerman P, Burns T, Xu J, Miers L, Pleasure D. Mice Hemizygous for a Pathogenic Mitofusin-2 Allele Exhibit Hind Limb/Foot Gait Deficits and Phenotypic Perturbations in Nerve and Muscle. PLoS One 2016; 11:e0167573. [PMID: 27907123 PMCID: PMC5132404 DOI: 10.1371/journal.pone.0167573] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 11/16/2016] [Indexed: 12/31/2022] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A), the most common axonal form of hereditary sensory motor neuropathy, is caused by mutations of mitofusin-2 (MFN2). Mitofusin-2 is a GTPase required for fusion of mitochondrial outer membranes, repair of damaged mitochondria, efficient mitochondrial energetics, regulation of mitochondrial-endoplasmic reticulum calcium coupling and axonal transport of mitochondria. We knocked T105M MFN2 preceded by a loxP-flanked STOP sequence into the mouse Rosa26 locus to permit cell type-specific expression of this pathogenic allele. Crossing these mice with nestin-Cre transgenic mice elicited T105M MFN2 expression in neuroectoderm, and resulted in diminished numbers of mitochondria in peripheral nerve axons, an alteration in skeletal muscle fiber type distribution, and a gait abnormality.
Collapse
Affiliation(s)
- Peter Bannerman
- Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children, Northern California, Sacramento, California, United States of America
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, California, United States of America
- * E-mail:
| | - Travis Burns
- Department of Neurology, University of California Davis, Sacramento, California, United States of America
| | - Jie Xu
- Department of Neurology, University of California Davis, Sacramento, California, United States of America
| | - Laird Miers
- Department of Neurology, University of California Davis, Sacramento, California, United States of America
| | - David Pleasure
- Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children, Northern California, Sacramento, California, United States of America
- Department of Neurology, University of California Davis, Sacramento, California, United States of America
| |
Collapse
|
37
|
Kozol RA, Abrams AJ, James DM, Buglo E, Yan Q, Dallman JE. Function Over Form: Modeling Groups of Inherited Neurological Conditions in Zebrafish. Front Mol Neurosci 2016; 9:55. [PMID: 27458342 PMCID: PMC4935692 DOI: 10.3389/fnmol.2016.00055] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022] Open
Abstract
Zebrafish are a unique cell to behavior model for studying the basic biology of human inherited neurological conditions. Conserved vertebrate genetics and optical transparency provide in vivo access to the developing nervous system as well as high-throughput approaches for drug screens. Here we review zebrafish modeling for two broad groups of inherited conditions that each share genetic and molecular pathways and overlap phenotypically: neurodevelopmental disorders such as Autism Spectrum Disorders (ASD), Intellectual Disability (ID) and Schizophrenia (SCZ), and neurodegenerative diseases, such as Cerebellar Ataxia (CATX), Hereditary Spastic Paraplegia (HSP) and Charcot-Marie Tooth Disease (CMT). We also conduct a small meta-analysis of zebrafish orthologs of high confidence neurodevelopmental disorder and neurodegenerative disease genes by looking at duplication rates and relative protein sizes. In the past zebrafish genetic models of these neurodevelopmental disorders and neurodegenerative diseases have provided insight into cellular, circuit and behavioral level mechanisms contributing to these conditions. Moving forward, advances in genetic manipulation, live imaging of neuronal activity and automated high-throughput molecular screening promise to help delineate the mechanistic relationships between different types of neurological conditions and accelerate discovery of therapeutic strategies.
Collapse
Affiliation(s)
- Robert A. Kozol
- Department of Biology, University of MiamiCoral Gables, FL, USA
| | - Alexander J. Abrams
- Department of Human Genetics, John P. Hussman Institute for Human Genomics, Dr. John T. Macdonald Foundation, University of MiamiMiami, FL, USA
| | - David M. James
- Department of Biology, University of MiamiCoral Gables, FL, USA
| | - Elena Buglo
- Department of Human Genetics, John P. Hussman Institute for Human Genomics, Dr. John T. Macdonald Foundation, University of MiamiMiami, FL, USA
| | - Qing Yan
- Department of Biology, University of MiamiCoral Gables, FL, USA
| | | |
Collapse
|
38
|
Perez-Siles G, Ly C, Grant A, Drew AP, Yiu EM, Ryan MM, Chuang DT, Tso SC, Nicholson GA, Kennerson ML. Pathogenic mechanisms underlying X-linked Charcot-Marie-Tooth neuropathy (CMTX6) in patients with a pyruvate dehydrogenase kinase 3 mutation. Neurobiol Dis 2016; 94:237-44. [PMID: 27388934 DOI: 10.1016/j.nbd.2016.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/22/2016] [Accepted: 07/03/2016] [Indexed: 10/21/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral neuropathy. An X-linked form of CMT (CMTX6) is caused by a missense mutation (R158H) in the pyruvate dehydrogenase kinase isoenzyme 3 (PDK3) gene. PDK3 is one of 4 isoenzymes that negatively regulate the activity of the pyruvate dehydrogenase complex (PDC) by reversible phosphorylation of its first catalytic component pyruvate dehydrogenase (designated as E1). Mitochondrial PDC catalyses the oxidative decarboxylation of pyruvate to acetyl CoA and links glycolysis to the energy-producing Krebs cycle. We have previously shown the R158H mutation confers PDK3 enzyme hyperactivity. In this study we demonstrate that the increased PDK3 activity in patient fibroblasts (PDK3(R158H)) leads to the attenuation of PDC through hyper-phosphorylation of E1 at selected serine residues. This hyper-phosphorylation can be reversed by treating the PDK3(R158H) fibroblasts with the PDK inhibitor dichloroacetate (DCA). In the patient cells, down-regulation of PDC leads to increased lactate, decreased ATP and alteration of the mitochondrial network. Our findings highlight the potential to develop specific drug targeting of the mutant PDK3 as a therapeutic approach to treating CMTX6.
Collapse
Affiliation(s)
- Gonzalo Perez-Siles
- Northcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW, Australia; Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
| | - Carolyn Ly
- Northcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW, Australia
| | - Adrienne Grant
- Northcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW, Australia
| | - Alexander P Drew
- Northcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW, Australia
| | - Eppie M Yiu
- Department of Neurology, Royal Children's Hospital, Flemington Road, Parkville, VIC, Australia; Neuroscience Research, Murdoch Childrens Research Institute, Melbourne, VIC, Australia; Department of Pediatrics, The University of Melbourne, VIC, Australia
| | - Monique M Ryan
- Department of Neurology, Royal Children's Hospital, Flemington Road, Parkville, VIC, Australia; Neuroscience Research, Murdoch Childrens Research Institute, Melbourne, VIC, Australia; Department of Pediatrics, The University of Melbourne, VIC, Australia
| | - David T Chuang
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Shih-Chia Tso
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Garth A Nicholson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW, Australia; Molecular Medicine Laboratory, Concord Hospital, Concord, NSW, Australia; Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Marina L Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW, Australia; Molecular Medicine Laboratory, Concord Hospital, Concord, NSW, Australia; Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
| |
Collapse
|
39
|
Pareyson D, Saveri P, Sagnelli A, Piscosquito G. Mitochondrial dynamics and inherited peripheral nerve diseases. Neurosci Lett 2015; 596:66-77. [PMID: 25847151 DOI: 10.1016/j.neulet.2015.04.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 04/01/2015] [Accepted: 04/02/2015] [Indexed: 12/20/2022]
Abstract
Peripheral nerves have peculiar energetic requirements because of considerable length of axons and therefore correct mitochondria functioning and distribution along nerves is fundamental. Mitochondrial dynamics refers to the continuous change in size, shape, and position of mitochondria within cells. Abnormalities of mitochondrial dynamics produced by mutations in proteins involved in mitochondrial fusion (mitofusin-2, MFN2), fission (ganglioside-induced differentiation-associated protein-1, GDAP1), and mitochondrial axonal transport usually present with a Charcot-Marie-Tooth disease (CMT) phenotype. MFN2 mutations cause CMT type 2A by altering mitochondrial fusion and trafficking along the axonal microtubule system. CMT2A is an axonal autosomal dominant CMT type which in most cases is characterized by early onset and rather severe course. GDAP1 mutations also alter fission, fusion and transport of mitochondria and are associated either with recessive demyelinating (CMT4A) and axonal CMT (AR-CMT2K) and, less commonly, with dominant, milder, axonal CMT (CMT2K). OPA1 (Optic Atrophy-1) is involved in fusion of mitochondrial inner membrane, and its heterozygous mutations lead to early-onset and progressive dominant optic atrophy which may be complicated by other neurological symptoms including peripheral neuropathy. Mutations in several proteins fundamental for the axonal transport or forming the axonal cytoskeleton result in peripheral neuropathy, i.e., CMT, distal hereditary motor neuropathy (dHMN) or hereditary sensory and autonomic neuropathy (HSAN), as well as in hereditary spastic paraplegia. Indeed, mitochondrial transport involves directly or indirectly components of the kinesin superfamily (KIF5A, KIF1A, KIF1B), responsible of anterograde transport, and of the dynein complex and related proteins (DYNC1H1, dynactin, dynamin-2), implicated in retrograde flow. Microtubules, neurofilaments, and chaperones such as heat shock proteins (HSPs) also have a fundamental role in mitochondrial transport and mutations in some of related encoding genes cause peripheral neuropathy (TUBB3, NEFL, HSPB1, HSPB8, HSPB3, DNAJB2). In this review, we address the abnormalities in mitochondrial dynamics and their role in determining CMT disease and related neuropathies.
Collapse
Affiliation(s)
- Davide Pareyson
- Clinic of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences - IRCCS Foundation, "C. Besta" Neurological Institute, Milan, Italy.
| | - Paola Saveri
- Clinic of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences - IRCCS Foundation, "C. Besta" Neurological Institute, Milan, Italy
| | - Anna Sagnelli
- Clinic of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences - IRCCS Foundation, "C. Besta" Neurological Institute, Milan, Italy
| | - Giuseppe Piscosquito
- Clinic of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences - IRCCS Foundation, "C. Besta" Neurological Institute, Milan, Italy
| |
Collapse
|