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Abati E, Rizzuti M, Anastasia A, Comi GP, Corti S, Rizzo F. Charcot-Marie-Tooth type 2A in vivo models: Current updates. J Cell Mol Med 2024; 28:e18293. [PMID: 38722298 PMCID: PMC11081012 DOI: 10.1111/jcmm.18293] [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: 01/16/2024] [Revised: 03/13/2024] [Accepted: 03/25/2024] [Indexed: 05/12/2024] Open
Abstract
Charcot-Marie-Tooth type 2A (CMT2A) is an inherited sensorimotor neuropathy associated with mutations within the Mitofusin 2 (MFN2) gene. These mutations impair normal mitochondrial functioning via different mechanisms, disturbing the equilibrium between mitochondrial fusion and fission, of mitophagy and mitochondrial axonal transport. Although CMT2A disease causes a significant disability, no resolutive treatment for CMT2A patients to date. In this context, reliable experimental models are essential to precisely dissect the molecular mechanisms of disease and to devise effective therapeutic strategies. The most commonly used models are either in vitro or in vivo, and among the latter murine models are by far the most versatile and popular. Here, we critically revised the most relevant literature focused on the experimental models, providing an update on the mammalian models of CMT2A developed to date. We highlighted the different phenotypic, histopathological and molecular characteristics, and their use in translational studies for bringing potential therapies from the bench to the bedside. In addition, we discussed limitations of these models and perspectives for future improvement.
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Affiliation(s)
- Elena Abati
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore PoliclinicoMilanItaly
- Department of Pathophysiology and Transplantation, Dino Ferrari CenterUniversità degli Studi di MilanoMilanItaly
| | - Mafalda Rizzuti
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore PoliclinicoMilanItaly
| | - Alessia Anastasia
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore PoliclinicoMilanItaly
| | - Giacomo Pietro Comi
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore PoliclinicoMilanItaly
- Department of Pathophysiology and Transplantation, Dino Ferrari CenterUniversità degli Studi di MilanoMilanItaly
| | - Stefania Corti
- Department of Pathophysiology and Transplantation, Dino Ferrari CenterUniversità degli Studi di MilanoMilanItaly
- Neuromuscular and Rare Diseases Unit, Department of NeuroscienceFondazione IRCCS Ca' Granda Ospedale Maggiore PoliclinicoMilanItaly
| | - Federica Rizzo
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore PoliclinicoMilanItaly
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Alberti C, Rizzo F, Anastasia A, Comi G, Corti S, Abati E. Charcot-Marie-tooth disease type 2A: An update on pathogenesis and therapeutic perspectives. Neurobiol Dis 2024; 193:106467. [PMID: 38452947 DOI: 10.1016/j.nbd.2024.106467] [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: 01/03/2024] [Revised: 03/04/2024] [Accepted: 03/04/2024] [Indexed: 03/09/2024] Open
Abstract
Mutations in the gene encoding MFN2 have been identified as associated with Charcot-Marie-Tooth disease type 2A (CMT2A), a neurological disorder characterized by a broad clinical phenotype involving the entire nervous system. MFN2, a dynamin-like GTPase protein located on the outer mitochondrial membrane, is well-known for its involvement in mitochondrial fusion. Numerous studies have demonstrated its participation in a network crucial for various other mitochondrial functions, including mitophagy, axonal transport, and its controversial role in endoplasmic reticulum (ER)-mitochondria contacts. Considerable progress has been made in the last three decades in elucidating the disease pathogenesis, aided by the generation of animal and cellular models that have been instrumental in studying disease physiology. A review of the literature reveals that, up to now, no definitive pharmacological treatment for any CMT2A variant has been established; nonetheless, recent years have witnessed substantial progress. Many treatment approaches, especially concerning molecular therapy, such as histone deacetylase inhibitors, peptide therapy to increase mitochondrial fusion, the new therapeutic strategies based on MF1/MF2 balance, and SARM1 inhibitors, are currently in preclinical testing. The literature on gene silencing and gene replacement therapies is still limited, except for a recent study by Rizzo et al.(Rizzo et al., 2023), which recently first achieved encouraging results in in vitro and in vivo models of the disease. The near-future goal for these promising therapies is to progress to the stage of clinical translation.
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Affiliation(s)
- Claudia Alberti
- Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy
| | - Federica Rizzo
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Alessia Anastasia
- Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Giacomo Comi
- Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy; Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefania Corti
- Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy; Neuromuscular and Rare Diseases Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Elena Abati
- Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy; Neurology Unit, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
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Elbert A, Dixon K, Shen Y, Hamilton S, Boerkoel CF, Jones SJ, Kanungo AK. Mitofusin 2 Variant Presenting With a Phenotype of Multiple System Atrophy of Cerebellar Subtype. Neurol Genet 2024; 10:e200114. [PMID: 38170145 PMCID: PMC10759145 DOI: 10.1212/nxg.0000000000200114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 11/01/2023] [Indexed: 01/05/2024]
Abstract
Objectives To investigate the etiology of cerebellar ataxia in an adult male patient. Methods We performed standard neurologic assessment and genome sequencing of a 62-year-old man with rapidly progressive balance and gait abnormalities. Results The propositus exhibited cognitive dysfunction, mild appendicular bradykinesia, prominent appendicular ataxia, dysarthria, and hypomimia with minimal dysautonomic symptoms. Nerve conduction studies showed mild peripheral sensory neuropathy and normal motor nerve conduction velocities. Brain imaging showed progressive cerebellar atrophy and gliosis of the olivopontocerebellar fibers, characterized by T2 hyperintensity within the pons. Genetic testing revealed a likely pathogenic germline variant in MFN2 (NM_014874: c.[838C>T];[=], p.(R280C)) in the GTPase domain (G) interface; pathogenic variants of MFN2 typically cause hereditary sensory and motor neuropathy VI or Charcot-Marie-Tooth disease 2A. The presence of progressive ataxia, "hot cross bun" sign, and dysautonomia has been associated with multiple system atrophy, cerebellar type (MSA-C). Discussion We describe progressive cerebellar ataxia in an individual with a deleterious variant in MFN2. Our findings suggest that pathogenic variants in MFN2 can result in a spectrum of phenotypes including cerebellar ataxia with cerebellar-pontine atrophy in the absence of significant neuropathy and in a manner closely resembling MSA-C.
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Affiliation(s)
- Adrienne Elbert
- From the Department of Medical Genetics (A.E., K.D., C.F.B., S.J.J.), University of British Columbia; Provincial Medical Genetics Program (A.E., S.H., C.B.), B.C. Women's Hospital and Health Centre; Canada's Michael Smith Genome Sciences Centre (K.D., Y.S., S.J.J.), BC Cancer; Fraser Health Movement Disorders Clinic (A.K.K.), Jim Pattison Outpatient Care and Surgery Centre, Surrey; and Department of Medicine (A.K.K.), Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Katherine Dixon
- From the Department of Medical Genetics (A.E., K.D., C.F.B., S.J.J.), University of British Columbia; Provincial Medical Genetics Program (A.E., S.H., C.B.), B.C. Women's Hospital and Health Centre; Canada's Michael Smith Genome Sciences Centre (K.D., Y.S., S.J.J.), BC Cancer; Fraser Health Movement Disorders Clinic (A.K.K.), Jim Pattison Outpatient Care and Surgery Centre, Surrey; and Department of Medicine (A.K.K.), Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Yaoqing Shen
- From the Department of Medical Genetics (A.E., K.D., C.F.B., S.J.J.), University of British Columbia; Provincial Medical Genetics Program (A.E., S.H., C.B.), B.C. Women's Hospital and Health Centre; Canada's Michael Smith Genome Sciences Centre (K.D., Y.S., S.J.J.), BC Cancer; Fraser Health Movement Disorders Clinic (A.K.K.), Jim Pattison Outpatient Care and Surgery Centre, Surrey; and Department of Medicine (A.K.K.), Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Sara Hamilton
- From the Department of Medical Genetics (A.E., K.D., C.F.B., S.J.J.), University of British Columbia; Provincial Medical Genetics Program (A.E., S.H., C.B.), B.C. Women's Hospital and Health Centre; Canada's Michael Smith Genome Sciences Centre (K.D., Y.S., S.J.J.), BC Cancer; Fraser Health Movement Disorders Clinic (A.K.K.), Jim Pattison Outpatient Care and Surgery Centre, Surrey; and Department of Medicine (A.K.K.), Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Cornelius F Boerkoel
- From the Department of Medical Genetics (A.E., K.D., C.F.B., S.J.J.), University of British Columbia; Provincial Medical Genetics Program (A.E., S.H., C.B.), B.C. Women's Hospital and Health Centre; Canada's Michael Smith Genome Sciences Centre (K.D., Y.S., S.J.J.), BC Cancer; Fraser Health Movement Disorders Clinic (A.K.K.), Jim Pattison Outpatient Care and Surgery Centre, Surrey; and Department of Medicine (A.K.K.), Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Steven J Jones
- From the Department of Medical Genetics (A.E., K.D., C.F.B., S.J.J.), University of British Columbia; Provincial Medical Genetics Program (A.E., S.H., C.B.), B.C. Women's Hospital and Health Centre; Canada's Michael Smith Genome Sciences Centre (K.D., Y.S., S.J.J.), BC Cancer; Fraser Health Movement Disorders Clinic (A.K.K.), Jim Pattison Outpatient Care and Surgery Centre, Surrey; and Department of Medicine (A.K.K.), Division of Neurology, University of British Columbia, Vancouver, Canada
| | - Anish K Kanungo
- From the Department of Medical Genetics (A.E., K.D., C.F.B., S.J.J.), University of British Columbia; Provincial Medical Genetics Program (A.E., S.H., C.B.), B.C. Women's Hospital and Health Centre; Canada's Michael Smith Genome Sciences Centre (K.D., Y.S., S.J.J.), BC Cancer; Fraser Health Movement Disorders Clinic (A.K.K.), Jim Pattison Outpatient Care and Surgery Centre, Surrey; and Department of Medicine (A.K.K.), Division of Neurology, University of British Columbia, Vancouver, Canada
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Xu X, Lu F, Du S, Zhang L. A case report of peroneal muscle atrophy type 2A2 with central nervous system involvement as initial presentation. BMC Pediatr 2024; 24:21. [PMID: 38183043 PMCID: PMC10768097 DOI: 10.1186/s12887-023-04441-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 11/22/2023] [Indexed: 01/07/2024] Open
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) is a group of single-gene hereditary diseases of peripheral nerve with high clinical variability and genetic heterogeneity. The typical clinical manifestations include progressive muscle weakness and muscle atrophy in the distal extremities, accompanied by disappearance of tendon reflexes and distal sensory disturbances. CMT2A2 (OMIM: 609260) is caused by the mutation of MFN2 (OMIM: 608507), is the most common type of axonal pattern. Although a small number of patients with X-linked CMT1 (CMT1X) present with central nervous system involvement, including reversible white matter lesions, it is rarely in CMT2A2. CASE PRESENTATION A 3-year and 5-month-old girl had experienced motor lag, muscle tension, and abnormal gait for over a year. A reexamination of cranial MRI revealed an anterior enlargement of the abnormal signal range in the lateral ventricles and bilateral frontal lobes. And the whole exon sequencing showed that this girl carried a heterozygous missense mutation c.314C > T of MNF2 gene, inherited from her mother. CONCLUSIONS In this study, we retrospectively analyzed the clinical and molecular genetic findings of a child with Charcot-Marie-Tooth disease A2 with central nervous system involvement as the initial presentation, and explored its pathogenic mechanism.
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Affiliation(s)
- Xin Xu
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Guangzhou Road, Nanjing, Jiangsu, 211103, China
| | - Fen Lu
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Guangzhou Road, Nanjing, Jiangsu, 211103, China
| | - Senjie Du
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Guangzhou Road, Nanjing, Jiangsu, 211103, China
| | - Li Zhang
- Department of Rehabilitation, Children's Hospital of Nanjing Medical University, Guangzhou Road, Nanjing, Jiangsu, 211103, China.
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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.
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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
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Das R, Maity S, Das P, Kamal IM, Chakrabarti S, Chakrabarti O. CMT2A-linked MFN2 mutation, T206I promotes mitochondrial hyperfusion and predisposes cells towards mitophagy. Mitochondrion 2024; 74:101825. [PMID: 38092249 DOI: 10.1016/j.mito.2023.101825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 12/01/2023] [Accepted: 12/09/2023] [Indexed: 12/21/2023]
Abstract
Mutations in Mitofusin2 (MFN2) associated with the pathology of the debilitating neuropathy Charcot-Marie-Tooth type 2A (CMT2A) are known to alter mitochondrial morphology. Previously, such mutations have been shown to elicit two diametrically opposite phenotypes - while some mutations have been causally linked to enhanced mitochondrial fragmentation, others have been shown to induce hyperfusion. Our study identifies one such MFN2 mutant, T206I that causes mitochondrial hyperfusion. Cells expressing this MFN2 mutant have elongated and interconnected mitochondria. T206I-MFN2 mutation in the GTPase domain increases MFN2 stability and renders cells susceptible to stress. We show that cells expressing T206I-MFN2 have a higher predisposition towards mitophagy under conditions of serum starvation. We also detect increased DRP1 recruitment onto the outer mitochondrial membrane, though the total DRP1 protein level remains unchanged. Here we have characterized a lesser studied CMT2A-linked MFN2 mutant to show that its presence affects mitochondrial morphology and homeostasis.
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Affiliation(s)
- Rajdeep Das
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhabha National Institute, India
| | - Sebabrata Maity
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhabha National Institute, India
| | - Palamou Das
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhabha National Institute, India
| | - Izaz Monir Kamal
- Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, CN 6, Sector V, Salt Lake, Kolkata 700091, India; Academy of Scientific and Innovative Research (AcSIR), Gaziabad, India
| | - Saikat Chakrabarti
- Structural Biology and Bioinformatics Division, CSIR Indian Institute of Chemical Biology, CN 6, Sector V, Salt Lake, Kolkata 700091, India; Academy of Scientific and Innovative Research (AcSIR), Gaziabad, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India; Homi Bhabha National Institute, India.
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Bremer J, Meinhardt A, Katona I, Senderek J, Kämmerer‐Gassler EK, Roos A, Ferbert A, Schröder JM, Nikolin S, Nolte K, Sellhaus B, Popzhelyazkova K, Tacke F, Schara‐Schmidt U, Neuen‐Jacob E, de Groote CC, de Jonghe P, Timmerman V, Baets J, Weis J. Myelin protein zero mutation-related hereditary neuropathies: Neuropathological insight from a new nerve biopsy cohort. Brain Pathol 2024; 34:e13200. [PMID: 37581289 PMCID: PMC10711263 DOI: 10.1111/bpa.13200] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 07/19/2023] [Indexed: 08/16/2023] Open
Abstract
Myelin protein zero (MPZ/P0) is a major structural protein of peripheral nerve myelin. Disease-associated variants in the MPZ gene cause a wide phenotypic spectrum of inherited peripheral neuropathies. Previous nerve biopsy studies showed evidence for subtype-specific morphological features. Here, we aimed at enhancing the understanding of these subtype-specific features and pathophysiological aspects of MPZ neuropathies. We examined archival material from two Central European centers and systematically determined genetic, clinical, and neuropathological features of 21 patients with MPZ mutations compared to 16 controls. Cases were grouped based on nerve conduction data into congenital hypomyelinating neuropathy (CHN; n = 2), demyelinating Charcot-Marie-Tooth (CMT type 1; n = 11), intermediate (CMTi; n = 3), and axonal CMT (type 2; n = 5). Six cases had combined muscle and nerve biopsies and one underwent autopsy. We detected four MPZ gene variants not previously described in patients with neuropathy. Light and electron microscopy of nerve biopsies confirmed fewer myelinated fibers, more onion bulbs and reduced regeneration in demyelinating CMT1 compared to CMT2/CMTi. In addition, we observed significantly more denervated Schwann cells, more collagen pockets, fewer unmyelinated axons per Schwann cell unit and a higher density of Schwann cell nuclei in CMT1 compared to CMT2/CMTi. CHN was characterized by basal lamina onion bulb formation, a further increase in Schwann cell density and hypomyelination. Most late onset axonal neuropathy patients showed microangiopathy. In the autopsy case, we observed prominent neuromatous hyperinnervation of the spinal meninges. In four of the six muscle biopsies, we found marked structural mitochondrial abnormalities. These results show that MPZ alterations not only affect myelinated nerve fibers, leading to either primarily demyelinating or axonal changes, but also affect non-myelinated nerve fibers. The autopsy case offers insight into spinal nerve root pathology in MPZ neuropathy. Finally, our data suggest a peculiar association of MPZ mutations with mitochondrial alterations in muscle.
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Affiliation(s)
- Juliane Bremer
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
| | - Axel Meinhardt
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
| | - Istvan Katona
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
| | - Jan Senderek
- Friedrich Baur Institute at the Department of NeurologyUniversity Hospital, LMU MunichMunichGermany
| | | | - Andreas Roos
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
- Department of NeuropaediatricsUniversity of EssenEssenGermany
| | | | | | - Stefan Nikolin
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
| | - Kay Nolte
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
| | - Bernd Sellhaus
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
| | | | - Frank Tacke
- Department of Hepatology and Gastroenterology, Charité—Universitätsmedizin BerlinCampus Virchow‐Klinikum (CVK) and Campus Charité Mitte (CCM)BerlinGermany
| | | | - Eva Neuen‐Jacob
- Department of NeuropathologyUniversity Hospital, Heinrich‐Heine University DüsseldorfDüsseldorfGermany
| | - Chantal Ceuterick de Groote
- Laboratory of Neuromuscular Pathology, Institute Born‐Bunge, and Translational Neurosciences, Faculty of MedicineUniversity of AntwerpBelgium
| | - Peter de Jonghe
- Laboratory of Neuromuscular Pathology, Institute Born‐Bunge, and Translational Neurosciences, Faculty of MedicineUniversity of AntwerpBelgium
- Department of NeurologyUniversity Hospital AntwerpAntwerpBelgium
| | - Vincent Timmerman
- Laboratory of Neuromuscular Pathology, Institute Born‐Bunge, and Translational Neurosciences, Faculty of MedicineUniversity of AntwerpBelgium
- Peripheral Neuropathy Research Group, Department of Biomedical SciencesUniversity of AntwerpAntwerpBelgium
| | - Jonathan Baets
- Laboratory of Neuromuscular Pathology, Institute Born‐Bunge, and Translational Neurosciences, Faculty of MedicineUniversity of AntwerpBelgium
- Department of NeurologyUniversity Hospital AntwerpAntwerpBelgium
| | - Joachim Weis
- Institute of NeuropathologyRWTH Aachen University HospitalAachenGermany
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8
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Conti F, Di Martino S, Drago F, Bucolo C, Micale V, Montano V, Siciliano G, Mancuso M, Lopriore P. Red Flags in Primary Mitochondrial Diseases: What Should We Recognize? Int J Mol Sci 2023; 24:16746. [PMID: 38069070 PMCID: PMC10706469 DOI: 10.3390/ijms242316746] [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: 11/01/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/18/2023] Open
Abstract
Primary mitochondrial diseases (PMDs) are complex group of metabolic disorders caused by genetically determined impairment of the mitochondrial oxidative phosphorylation (OXPHOS). The unique features of mitochondrial genetics and the pivotal role of mitochondria in cell biology explain the phenotypical heterogeneity of primary mitochondrial diseases and the resulting diagnostic challenges that follow. Some peculiar features ("red flags") may indicate a primary mitochondrial disease, helping the physician to orient in this diagnostic maze. In this narrative review, we aimed to outline the features of the most common mitochondrial red flags offering a general overview on the topic that could help physicians to untangle mitochondrial medicine complexity.
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Affiliation(s)
- Federica Conti
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Serena Di Martino
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Filippo Drago
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Claudio Bucolo
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
- Center for Research in Ocular Pharmacology-CERFO, University of Catania, 95213 Catania, Italy
| | - Vincenzo Micale
- Department of Biomedical and Biotechnological Science, School of Medicine, University of Catania, 95123 Catania, Italy; (F.C.); (S.D.M.); (C.B.); (V.M.)
| | - Vincenzo Montano
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Gabriele Siciliano
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Michelangelo Mancuso
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
| | - Piervito Lopriore
- Neurological Institute, Department of Clinical and Experimental Medicine, University of Pisa, 56126 Pisa, Italy (P.L.)
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9
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Rizzo F, Bono S, Ruepp MD, Salani S, Ottoboni L, Abati E, Melzi V, Cordiglieri C, Pagliarani S, De Gioia R, Anastasia A, Taiana M, Garbellini M, Lodato S, Kunderfranco P, Cazzato D, Cartelli D, Lonati C, Bresolin N, Comi G, Nizzardo M, Corti S. Combined RNA interference and gene replacement therapy targeting MFN2 as proof of principle for the treatment of Charcot-Marie-Tooth type 2A. Cell Mol Life Sci 2023; 80:373. [PMID: 38007410 PMCID: PMC10676309 DOI: 10.1007/s00018-023-05018-w] [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: 04/14/2023] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/27/2023]
Abstract
Mitofusin-2 (MFN2) is an outer mitochondrial membrane protein essential for mitochondrial networking in most cells. Autosomal dominant mutations in the MFN2 gene cause Charcot-Marie-Tooth type 2A disease (CMT2A), a severe and disabling sensory-motor neuropathy that impacts the entire nervous system. Here, we propose a novel therapeutic strategy tailored to correcting the root genetic defect of CMT2A. Though mutant and wild-type MFN2 mRNA are inhibited by RNA interference (RNAi), the wild-type protein is restored by overexpressing cDNA encoding functional MFN2 modified to be resistant to RNAi. We tested this strategy in CMT2A patient-specific human induced pluripotent stem cell (iPSC)-differentiated motor neurons (MNs), demonstrating the correct silencing of endogenous MFN2 and replacement with an exogenous copy of the functional wild-type gene. This approach significantly rescues the CMT2A MN phenotype in vitro, stabilizing the altered axonal mitochondrial distribution and correcting abnormal mitophagic processes. The MFN2 molecular correction was also properly confirmed in vivo in the MitoCharc1 CMT2A transgenic mouse model after cerebrospinal fluid (CSF) delivery of the constructs into newborn mice using adeno-associated virus 9 (AAV9). Altogether, our data support the feasibility of a combined RNAi and gene therapy strategy for treating the broad spectrum of human diseases associated with MFN2 mutations.
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Affiliation(s)
- Federica Rizzo
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Silvia Bono
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Marc David Ruepp
- United Kingdom Dementia Research Institute Centre, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Sabrina Salani
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Linda Ottoboni
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Elena Abati
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Valentina Melzi
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Chiara Cordiglieri
- Istituto Di Genetica Molecolare "Romeo Ed Enrica Invernizzi", Milan, Italy
| | - Serena Pagliarani
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Roberta De Gioia
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Alessia Anastasia
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Michela Taiana
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Simona Lodato
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, 20072, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano, 20089, Milan, Italy
| | - Paolo Kunderfranco
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele, 20072, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano, 20089, Milan, Italy
| | - Daniele Cazzato
- Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | | | - Caterina Lonati
- Center for Preclinical Research, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Pace 9, 20100, Milan, Italy
| | - Nereo Bresolin
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy
| | - Giacomo Comi
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy
| | - Monica Nizzardo
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefania Corti
- Dino Ferrari Centre, Neuroscience Section, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Milan, Italy.
- Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Neuromuscular and Rare Diseases Unit, Milan, Italy.
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10
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Zhang Y, Pang D, Wang Z, Ma L, Chen Y, Yang L, Xiao W, Yuan H, Chang F, Ouyang H. An integrative analysis of genotype-phenotype correlation in Charcot Marie Tooth type 2A disease with MFN2 variants: A case and systematic review. Gene 2023; 883:147684. [PMID: 37536398 DOI: 10.1016/j.gene.2023.147684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/24/2023] [Accepted: 07/31/2023] [Indexed: 08/05/2023]
Abstract
Dominant genetic variants in the mitofusin 2 (MFN2) gene lead to Charcot-Marie-Tooth type 2A (CMT2A), a neurodegenerative disease caused by genetic defects that directly damage axons. In this study, we reported a proband with a pathogenic variant in the GTPase domain of MFN2, c.494A > G (p.His165Arg). To date, at least 184 distinct MFN2 variants identified in 944 independent probands have been reported in 131 references. However, the field of medical genetics has long been challenged by how genetic variation in the MFN2 gene is associated with disease phenotypes. Here, by collating the MFN2 variant data and patient clinical information from Leiden Open Variant Database 3.0, NCBI clinvar database, and available related references in PubMed, we determined the mutation frequency, age of onset, sex ratio, and geographical distribution. Furthermore, the results of an analysis examining the relationship between variants and phenotypes from multiple genetic perspectives indicated that insertion and deletions (indels), copy number variants (CNVs), duplication variants, and nonsense mutations in single nucleotide variants (SNVs) tend to be pathogenic, and the results emphasized the importance of the GTPase domain to the structure and function of MFN2. Overall, three reliable classification methods of MFN2 genotype-phenotype associations provide insights into the prediction of CMT2A disease severity. Of course, there are still many MFN2 variants that have not been given clear clinical significance, which requires clinicians to make more accurate clinical diagnoses.
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Affiliation(s)
- Yuanzhu Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Daxin Pang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China; Chongqing Research Institute, Jilin University, Chongqing 401120, China; Chongqing Jitang Biotechnology Research Institute Co., Ltd., Chongqing 401120, China.
| | - Ziru Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Lerong Ma
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Yiwu Chen
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Lin Yang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Wenyu Xiao
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China.
| | - Hongming Yuan
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China; Chongqing Research Institute, Jilin University, Chongqing 401120, China.
| | - Fei Chang
- Department of Orthopedics, The Second Hospital of Jilin University, Changchun 130022, China.
| | - Hongsheng Ouyang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Sciences, Jilin University, Changchun 130062, China; Chongqing Research Institute, Jilin University, Chongqing 401120, China; Chongqing Jitang Biotechnology Research Institute Co., Ltd., Chongqing 401120, China.
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11
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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.
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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
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12
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Stavropoulos F, Georgiou E, Schiza N, Bell S, Baloh RH, Kleopa KA, Sargiannidou I. Mitofusin 1 overexpression rescues the abnormal mitochondrial dynamics caused by the Mitofusin 2 K357T mutation in vitro. J Peripher Nerv Syst 2023; 28:329-340. [PMID: 37220142 DOI: 10.1111/jns.12564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/12/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Mitofusin 1 (MFN1) and MFN2 are outer mitochondrial membrane fusogenic proteins regulating mitochondrial network morphology. MFN2 mutations cause Charcot-Marie-Tooth type 2A (CMT2A), an axonal neuropathy characterized by mitochondrial fusion defects, which in the case of a GTPase domain mutant, were rescued following wild-type MFN1/2 (MFN1/2WT ) overexpression. In this study, we compared the therapeutic efficiency between MFN1WT and MFN2WT overexpression in correcting mitochondrial defects induced by the novel MFN2K357T mutation located in the highly conserved R3 region. METHODS Constructs expressing either MFN2K357T , MFN2WT , or MFN1WT under the ubiquitous chicken β-actin hybrid (CBh) promoter were generated. Flag or myc tag was used for their detection. Differentiated SH-SY5Y cells were single transfected with MFN1WT , MFN2WT , or MFN2K357T , as well as double transfected with MFN2K357T /MFN2WT or MFN2K357T /MFN1WT . RESULTS SH-SY5Y cells transfected with MFN2K357T exhibited severe perinuclear mitochondrial clustering with axon-like processes devoid of mitochondria. Single transfection with MFN1WT resulted in a more interconnected mitochondrial network than transfection with MFN2WT , accompanied by mitochondrial clusters. Double transfection of MFN2K357T with either MFN1WT or MFN2WT resolved the mutant-induced mitochondrial clusters and led to detectable mitochondria throughout the axon-like processes. MFN1WT showed higher efficacy than MFN2WT in rescuing these defects. INTERPRETATION These results further demonstrate the higher potential of MFN1WT over MFN2WT overexpression to rescue CMT2A-induced mitochondrial network abnormalities due to mutations outside the GTPase domain. This higher phenotypic rescue conferred by MFN1WT , possibly due to its higher mitochondrial fusogenic ability, may be applied to different CMT2A cases regardless of the MFN2 mutation type.
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Affiliation(s)
- Filippos Stavropoulos
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Elena Georgiou
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Natasa Schiza
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Shaughn Bell
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Robert H Baloh
- Global Head of Neuroscience, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, USA
| | - Kleopas A Kleopa
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Center for Neuromuscular Disorders and Center for Multiple Sclerosis and Related Disorders, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Irene Sargiannidou
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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13
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Muñoz JP, Basei FL, Rojas ML, Galvis D, Zorzano A. Mechanisms of Modulation of Mitochondrial Architecture. Biomolecules 2023; 13:1225. [PMID: 37627290 PMCID: PMC10452872 DOI: 10.3390/biom13081225] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/27/2023] [Accepted: 08/01/2023] [Indexed: 08/27/2023] Open
Abstract
Mitochondrial network architecture plays a critical role in cellular physiology. Indeed, alterations in the shape of mitochondria upon exposure to cellular stress can cause the dysfunction of these organelles. In this scenario, mitochondrial dynamics proteins and the phospholipid composition of the mitochondrial membrane are key for fine-tuning the modulation of mitochondrial architecture. In addition, several factors including post-translational modifications such as the phosphorylation, acetylation, SUMOylation, and o-GlcNAcylation of mitochondrial dynamics proteins contribute to shaping the plasticity of this architecture. In this regard, several studies have evidenced that, upon metabolic stress, mitochondrial dynamics proteins are post-translationally modified, leading to the alteration of mitochondrial architecture. Interestingly, several proteins that sustain the mitochondrial lipid composition also modulate mitochondrial morphology and organelle communication. In this context, pharmacological studies have revealed that the modulation of mitochondrial shape and function emerges as a potential therapeutic strategy for metabolic diseases. Here, we review the factors that modulate mitochondrial architecture.
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Affiliation(s)
- Juan Pablo Muñoz
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
- Institut d’Investigació Biomèdica Sant Pau (IIB SANT PAU), 08041 Barcelona, Spain
| | - Fernanda Luisa Basei
- Faculdade de Ciências Farmacêuticas, Universidade Estadual de Campinas, 13083-871 Campinas, SP, Brazil
| | - María Laura Rojas
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
| | - David Galvis
- Programa de Química Farmacéutica, Universidad CES, Medellín 050031, Colombia
| | - Antonio Zorzano
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
- Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
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14
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Vinciguerra C, Di Fonzo A, Monfrini E, Ronchi D, Cuoco S, Piscosquito G, Barone P, Pellecchia MT. Case report: Asp194Ala variant in MFN2 is associated with ALS-FTD in an Italian family. Front Genet 2023; 14:1235887. [PMID: 37547466 PMCID: PMC10400291 DOI: 10.3389/fgene.2023.1235887] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 07/10/2023] [Indexed: 08/08/2023] Open
Abstract
Background: MFN2 gene encodes the protein Mitofusin 2, involved in essential mitochondrial functions such as fusion, trafficking, turnover, and cellular interactions. We describe a family carrying a novel MFN2 mutation associated with ALS-frontotemporal dementia (FTD) clinical phenotype in the mother and Charcot-Marie-Tooth disease type 2A (CMT2A) in her son. Case presentation: The mother, a 67-year-old woman, referred to us for a three year-history of mood disturbance and gait impairment, and a more recent hypophonia, dysarthria, dysphagia, and diffuse muscle wasting. Family history was positive for psychiatric disorders and gait disturbances. Brain 18F-FDG PET showed severe hypometabolism in the fronto-temporal brain cortex bilaterally. Electrodiagnostic studies (EDX) showed severe motor axonopathy in the bulbar, cervical and lumbosacral districts. Her 41-year-old son had a history of mood depression and sensory disturbances in the limbs, along with mild muscle wasting, weakness, and reduced reflexes. Nerve conduction studies revealed a moderate sensory-motor polyneuropathy, while brain MRI was normal. Whole exome sequencing of the patients' DNA identified the novel MFN2 (NM_014874.4) variant c.581A>C p.(Asp194Ala). Conclusion: Our findings provide evidence of heterogenous clinical manifestations in family members sharing the same MFN2 molecular defect. Additionally, we present the first documented case of ASL-FTD associated with an MFN2 mutation, thereby expanding the range of MFN-related disorders. Further research involving larger cohorts of patients will be needed to better understand the role of MFN2 as a contributing gene in the development of ALS-FTD.
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Affiliation(s)
- C. Vinciguerra
- Center for Neurodegenerative Diseases (CEMAND), Department of Medicine, Surgery and Odontology “Scuola Medica Salernitana”, University of Salerno, Salerno, Italy
| | - A. Di Fonzo
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- IRCCS Fondazione Ca’ Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - E. Monfrini
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- IRCCS Fondazione Ca’ Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - D. Ronchi
- Dino Ferrari Center, Department of Pathophysiology and Transplantation, University of Milan, Milan, Italy
- IRCCS Fondazione Ca’ Granda Ospedale Maggiore Policlinico, Neurology Unit, Milan, Italy
| | - S. Cuoco
- Center for Neurodegenerative Diseases (CEMAND), Department of Medicine, Surgery and Odontology “Scuola Medica Salernitana”, University of Salerno, Salerno, Italy
| | - G. Piscosquito
- Center for Neurodegenerative Diseases (CEMAND), Department of Medicine, Surgery and Odontology “Scuola Medica Salernitana”, University of Salerno, Salerno, Italy
| | - P. Barone
- Center for Neurodegenerative Diseases (CEMAND), Department of Medicine, Surgery and Odontology “Scuola Medica Salernitana”, University of Salerno, Salerno, Italy
| | - M. T Pellecchia
- Center for Neurodegenerative Diseases (CEMAND), Department of Medicine, Surgery and Odontology “Scuola Medica Salernitana”, University of Salerno, Salerno, Italy
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15
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Ma Y, Duan X, Liu X, Fan D. Clinical and mutational spectrum of paediatric Charcot-Marie-Tooth disease in a large cohort of Chinese patients. Front Genet 2023; 14:1188361. [PMID: 37519884 PMCID: PMC10381926 DOI: 10.3389/fgene.2023.1188361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 07/03/2023] [Indexed: 08/01/2023] Open
Abstract
Background: Charcot-Marie-Tooth disease (CMT) is the most common inherited neurological disorder suffered in childhood. To date, the disease features have not been extensively characterized in the Chinese paediatric population. In this study, we aimed to analyse the clinical profiles and genetic distributions of a paediatric CMT cohort in China. Methods: A total of 181 paediatric CMT patients were enrolled. After preexcluding PMP22 duplication/deletion by multiplex ligation-dependent probe amplification (MLPA), Sanger sequencing, targeted next-generation sequencing (NGS) or whole-exome sequencing (WES) was performed to obtain a genetic diagnosis. Detailed information was collected to explore the spectrum of subtypes and genotype-phenotype correlations. Results: Pathogenic mutations were identified in 68% of patients in this study; with PMP22 duplication, MFN2 and GJB1 were the most frequent disease-causing genes. Of note, respect to the higher prevalence worldwide, CMT1A (18.2%) was relatively lower in our cohort. Besides, the mean age at onset (8.3 ± 5.7 years) was significantly older in our series. In genotype-phenotype analyse, PMP22 point mutations were considered the most severe genotypes and were mostly de novo. In addition, the de novo mutations were identified in up to 12.7% of all patients, which was higher than that in other studies. Conclusion: We identified a relatively lower detection rate of PMP22 duplication and a higher frequency of de novo variants among paediatric patients in China. We also identified the genetic and phenotypic heterogeneity of this cohort, which may provide clues for clinicians in directing genetic testing strategies for Chinese patients with early-onset CMT.
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Affiliation(s)
- Yan Ma
- Department of Neurology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
- Key Laboratory for Neuroscience, National Health Commission/Ministry of Education, Peking University, Beijing, China
| | | | - Xiaoxuan Liu
- Department of Neurology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
- Key Laboratory for Neuroscience, National Health Commission/Ministry of Education, Peking University, Beijing, China
| | - Dongsheng Fan
- Department of Neurology, Peking University Third Hospital, Beijing, China
- Beijing Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China
- Key Laboratory for Neuroscience, National Health Commission/Ministry of Education, Peking University, Beijing, China
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16
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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.
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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
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17
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Berth SH, Lloyd TE. Disruption of axonal transport in neurodegeneration. J Clin Invest 2023; 133:168554. [PMID: 37259916 DOI: 10.1172/jci168554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023] Open
Abstract
Neurons are markedly compartmentalized, which makes them reliant on axonal transport to maintain their health. Axonal transport is important for anterograde delivery of newly synthesized macromolecules and organelles from the cell body to the synapse and for the retrograde delivery of signaling endosomes and autophagosomes for degradation. Dysregulation of axonal transport occurs early in neurodegenerative diseases and plays a key role in axonal degeneration. Here, we provide an overview of mechanisms for regulation of axonal transport; discuss how these mechanisms are disrupted in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, hereditary spastic paraplegia, amyotrophic lateral sclerosis, and Charcot-Marie-Tooth disease; and discuss therapeutic approaches targeting axonal transport.
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18
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Li L, Wang W, Xu Q, Huang M. Asiatic acid improves insulin secretion of β cells in type 2 diabetes through TNF- α/Mfn2 pathway. Zhejiang Da Xue Xue Bao Yi Xue Ban 2023; 52:185-194. [PMID: 37283103 PMCID: PMC10409975 DOI: 10.3724/zdxbyxb-2022-0647] [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: 11/17/2022] [Accepted: 01/10/2023] [Indexed: 06/08/2023]
Abstract
OBJECTIVES To investigate the effects and molecular mechanisms of asiatic acid on β-cell function in type 2 diabetes mellitus (T2DM). METHODS The T2DM model was established by high fat diet and streptozotocin injection in ICR mice, and the effects of asiatic acid on glucose regulation were investigated in model mice. The islets were isolated from palmitic acid-treated diabetic mice. ELISA was used to detect the glucose-stimulated insulin secretion, tumor necrosis factor (TNF)-α and interleukin (IL)-6. ATP assay was applied to measure ATP production, and Western blotting was used to detect protein expression of mature β cell marker urocortin (Ucn) 3 and mitofusin (Mfn) 2. The regulatory effects of asiatic acid on glucose-stimulated insulin secretion (GSIS) and Ucn3 expression were also investigated after siRNA interference with Mfn2 or treatment with TNF-α. RESULTS Asiatic acid with the dose of 25 mg·kg-1·d-1 had the best glycemic control in T2DM mice and improved the homeostasis model assessment β index. Asiatic acid increased the expression of Mfn2 and Ucn3 protein and improved the GSIS function of diabetic β cells in vitro and in vivo (both P<0.05). Moreover, it improved the ATP production of islets of T2DM mice in vitro (P<0.05). Interfering Mfn2 with siRNA blocked the up-regulation of Ucn3 and GSIS induced by asiatic acid. Asiatic acid inhibited islet TNF-α content and increased Mfn2 and Ucn3 protein expression inhibited by TNF-α. CONCLUSIONS Asiatic acid improves β cell insulin secretion function in T2DM mice by maintaining the β cell maturity, which may be related to the TNF-α/Mfn2 pathway.
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Affiliation(s)
- Lu Li
- Department of Clinical Pharmacy, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
| | - Wei Wang
- Intensive Critical Care Unit, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Qiang Xu
- Department of Clinical Pharmacy, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Mingzhu Huang
- Department of Clinical Pharmacy, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
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19
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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.
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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
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20
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Zanfardino P, Longo G, Amati A, Morani F, Picardi E, Girolamo F, Pafundi M, Cox SN, Manzari C, Tullo A, Doccini S, Santorelli FM, Petruzzella V. Mitofusin 2 mutation drives cell proliferation in Charcot-Marie-Tooth 2A fibroblasts. Hum Mol Genet 2023; 32:333-350. [PMID: 35994048 DOI: 10.1093/hmg/ddac201] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/12/2022] [Accepted: 08/16/2022] [Indexed: 01/20/2023] Open
Abstract
Dominant mutations in ubiquitously expressed mitofusin 2 gene (MFN2) cause Charcot-Marie-Tooth type 2A (CMT2A; OMIM 609260), an inherited sensory-motor neuropathy that affects peripheral nerve axons. Mitofusin 2 protein has been found to take part in mitochondrial fusion, mitochondria-endoplasmic reticulum tethering, mitochondrial trafficking along axons, mitochondrial quality control and various types of cancer, in which MFN2 has been indicated as a tumor suppressor gene. Discordant data on the mitochondrial altered phenotypes in patient-derived fibroblasts harboring MFN2 mutations and in animal models have been reported. We addressed some of these issues by focusing on mitochondria behavior during autophagy and mitophagy in fibroblasts derived from a CMT2AMFN2 patient with an MFN2650G > T/C217F mutation in the GTPase domain. This study investigated mitochondrial dynamics, respiratory capacity and autophagy/mitophagy, to tackle the multifaceted MFN2 contribution to CMT2A pathogenesis. We found that MFN2 mutated fibroblasts showed impairment of mitochondrial morphology, bioenergetics capacity, and impairment of the early stages of autophagy, but not mitophagy. Unexpectedly, transcriptomic analysis of mutated fibroblasts highlighted marked differentially expressed pathways related to cell population proliferation and extracellular matrix organization. We consistently found the activation of mTORC2/AKT signaling and accelerated proliferation in the CMT2AMFN2 fibroblasts. In conclusion, our evidence indicates that MFN2 mutation can positively drive cell proliferation in CMT2AMFN2 fibroblasts.
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Affiliation(s)
- Paola Zanfardino
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Giovanna Longo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Alessandro Amati
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Federica Morani
- Department of Biology, University of Pisa, 56126 Pisa, Italy
| | - Ernesto Picardi
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, 70125 Bari, Italy
| | - Francesco Girolamo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Mariella Pafundi
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Sharon N Cox
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | - Caterina Manzari
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | - Apollonia Tullo
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, 70125 Bari, Italy
| | - Stefano Doccini
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, 56128 Pisa, Italy
| | - Filippo M Santorelli
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, 56128 Pisa, Italy
| | - Vittoria Petruzzella
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
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21
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Evaluation of optical coherence tomography findings and visual evoked potentials in Charcot-Marie-Tooth disease. Int Ophthalmol 2023; 43:333-341. [PMID: 35953577 DOI: 10.1007/s10792-022-02452-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 07/31/2022] [Indexed: 02/07/2023]
Abstract
PURPOSE To evaluate the spectral-domain optical coherence tomography (SD-OCT) findings and pattern visual evoked potential (VEP) in Charcot-Marie-Tooth (CMT) disease. METHODS Seventeen patients with CMT disease and 17 control subjects were included in the study. The patients were divided into two groups according to conduction velocity and inheritance pattern as demyelinating type (CMT 1) and axonal type (CMT 2). The average retinal nerve fiber layer (RNFL) thickness, RNFL thicknesses of all quadrants, and thicknesses of the ganglion cell layer complex (GCC) were measured using SD-OCT. Pattern VEP recordings were evaluated in both groups. RESULTS The average and four quadrants of RNFL thicknesses, and superior and inferior GCC thicknesses were significantly thinner in the CMT patients compared with healthy individuals, but there were no statistically significant differences between the CMT groups. There was a significant positive correlation between age and all RNFL and GCC thicknesses in the CMT 2 group and between age and RNFL thickness of the temporal quadrant in the CMT 1 group. P100 latencies were significantly delayed in the CMT groups compared with controls, and there were no significant differences in P100 latencies between the CMT groups (p < 0.001). VEP amplitudes were in normal ranges in the CMT groups. CONCLUSION This study showed that RNFL and GCC thicknesses were significantly reduced and VEP latencies were prolonged in patients with CMT with normal clinical examinations. Our results suggest that optic nerves may be affected more frequently in patients with CMT that is detected in clinical examinations.
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22
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Sato-Yamada Y, Strickland A, Sasaki Y, Bloom J, DiAntonio A, Milbrandt J. A SARM1-mitochondrial feedback loop drives neuropathogenesis in a Charcot-Marie-Tooth disease type 2A rat model. J Clin Invest 2022; 132:e161566. [PMID: 36287202 PMCID: PMC9711878 DOI: 10.1172/jci161566] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 10/11/2022] [Indexed: 11/17/2022] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is an axonal neuropathy caused by mutations in the mitofusin 2 (MFN2) gene. MFN2 mutations result in profound mitochondrial abnormalities, but the mechanism underlying the axonal pathology is unknown. Sterile α and Toll/IL-1 receptor motif-containing 1 (SARM1), the central executioner of axon degeneration, can induce neuropathy and is activated by dysfunctional mitochondria. We tested the role of SARM1 in a rat model carrying a dominant CMT2A mutation (Mfn2H361Y) that exhibits progressive dying-back axonal degeneration, neuromuscular junction (NMJ) abnormalities, muscle atrophy, and mitochondrial abnormalities - all hallmarks of the human disease. We generated Sarm1-KO (Sarm1-/-) and Mfn2H361Y Sarm1 double-mutant rats and found that deletion of Sarm1 rescued axonal, synaptic, muscle, and functional phenotypes, demonstrating that SARM1 was responsible for much of the neuropathology in this model. Despite the presence of mutant MFN2 protein in these double-mutant rats, loss of SARM1 also dramatically suppressed many mitochondrial defects, including the number, size, and cristae density defects of synaptic mitochondria. This surprising finding indicates that dysfunctional mitochondria activated SARM1 and that activated SARM1 fed back on mitochondria to exacerbate the mitochondrial pathology. As such, this work identifies SARM1 inhibition as a therapeutic candidate for the treatment of CMT2A and other neurodegenerative diseases with prominent mitochondrial pathology.
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Affiliation(s)
- Yurie Sato-Yamada
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Advanced Oral Science, Niigata University Graduate School of Medical and Dental Science, Niigata City, Japan
| | - Amy Strickland
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Yo Sasaki
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Joseph Bloom
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
- Needleman Center for Neurometabolism and Axonal Therapeutics, St. Louis, Missouri, USA
| | - Aaron DiAntonio
- Needleman Center for Neurometabolism and Axonal Therapeutics, St. Louis, Missouri, USA
- Department of Developmental Biology and
| | - Jeffrey Milbrandt
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, USA
- Needleman Center for Neurometabolism and Axonal Therapeutics, St. Louis, Missouri, USA
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, USA
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23
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Franco A, Dang X, Zhang L, Molinoff PB, Dorn GW. Mitochondrial Dysfunction and Pharmacodynamics of Mitofusin Activation in Murine Charcot-Marie-Tooth Disease Type 2A. J Pharmacol Exp Ther 2022; 383:137-148. [PMID: 36507849 PMCID: PMC9553116 DOI: 10.1124/jpet.122.001332] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/03/2022] [Indexed: 01/07/2023] Open
Abstract
Mitofusin (MFN) 1 and MFN2 are dynamin GTPase family mitochondrial proteins that mediate mitochondrial fusion requiring MFN conformational shifts, formation of macromolecular complexes on and between mitochondria, and GTP hydrolysis. Damaging MFN2 mutations cause an untreatable, largely pediatric progressive peripheral neuropathy, Charcot-Marie-Tooth (CMT) disease type 2A. We used small molecule allosteric mitofusin activators that promote MFN conformations favoring fusion to interrogate the effects of MFN2 conformation and GTPase activity on MFN2-mediated mitochondrial fusion and motility in vitro. We translated these findings in vivo by defining dose-dependent pharmacodynamic and disease-modifying effects of mitofusin activators in murine CMT2A. MFN2 catalytic GTPase activity and MFN2 conformational switching are essential for mitochondrial fusion, but the two processes are separate and dissociable. We report the first concentration-response relationships for mitofusin activators to stimulate mitochondrial transport through CMT2A neuronal axons, which is similar to their stimulation of mitochondrial fusion. In CMT2A mice, intermittent (daily short acting) and sustained (twice daily long acting) mitofusin activation were equally effective in reversing neuromuscular degeneration. Moreover, acute dose-dependent pharmacodynamic effects of mitofusin activators on mitochondrial transport through CMT2A neuronal axons anticipated those for long-term reversal of neurodegenerative phenotypes. A crossover study showed that CMT2A neuronal deficits recurred after mitofusin activators are discontinued, and revealed that CMT2A can be ameliorated by mitofusin activation even in old (>74 week) mice. These data add to our understanding of mitochondrial dysfunction induced by a CMT2A MFN2 GTPase mutation and provide additional information supporting the approach of pharmacological mitofusin activation in CMT2A. SIGNIFICANCE: This study interrogated the roles of MFN2 catalytic activity and allosteric activation on impaired mitochondrial fusion and neuronal transport as they impact an untreatable peripheral neuropathy caused by MFN2 mutations, Charcot-Marie-Tooth disease type 2A. The results mechanistically link mitochondrial fusion and motility to the relaxed MFN2 protein conformation and correction of mitochondrial abnormalities to in vivo reversal of neurodegeneration in murine CMT2A.
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Affiliation(s)
- Antonietta Franco
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri (A.F., X.D., L.Z., G.W.D.); Department of Cardiology, The First Affiliated Hospital of Xi'an Jiao Tong University, Xi'an, Shaanxi, China (X.D.); Mitochondria in Motion Inc., St. Louis, Missouri (L.Z.); and Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania (P.B.M.)
| | - Xiawei Dang
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri (A.F., X.D., L.Z., G.W.D.); Department of Cardiology, The First Affiliated Hospital of Xi'an Jiao Tong University, Xi'an, Shaanxi, China (X.D.); Mitochondria in Motion Inc., St. Louis, Missouri (L.Z.); and Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania (P.B.M.)
| | - Lihong Zhang
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri (A.F., X.D., L.Z., G.W.D.); Department of Cardiology, The First Affiliated Hospital of Xi'an Jiao Tong University, Xi'an, Shaanxi, China (X.D.); Mitochondria in Motion Inc., St. Louis, Missouri (L.Z.); and Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania (P.B.M.)
| | - Perry B Molinoff
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri (A.F., X.D., L.Z., G.W.D.); Department of Cardiology, The First Affiliated Hospital of Xi'an Jiao Tong University, Xi'an, Shaanxi, China (X.D.); Mitochondria in Motion Inc., St. Louis, Missouri (L.Z.); and Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania (P.B.M.)
| | - Gerald W Dorn
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri (A.F., X.D., L.Z., G.W.D.); Department of Cardiology, The First Affiliated Hospital of Xi'an Jiao Tong University, Xi'an, Shaanxi, China (X.D.); Mitochondria in Motion Inc., St. Louis, Missouri (L.Z.); and Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania (P.B.M.)
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24
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Babu K, Seamon K, Jewell A, Harrison A, Harper A, Al Saif H, Couser N. Hereditary motor and sensory neuropathy type VIA with optic nerve pallor in two sisters with pathologic myopia: a case series and review. Ophthalmic Genet 2022:1-6. [PMID: 36098092 DOI: 10.1080/13816810.2022.2116651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
PURPOSE Hereditary Motor Sensory Neuropathy Type VIA with Optic Atrophy (HMSN6A) is a rare variant subtype of mitofusin 2 (MFN2) associated Charcot-Marie-Tooth disease, with ophthalmic manifestations largely limited to optic atrophy. We report a case series of two sisters with HMSN6A corresponding to known variants in the MFN2 gene. The proband's mother, maternal aunt, and maternal grandfather were also reportedly affected with the condition, although not examined at our institution. The clinical presentations of the proband and her sister are reviewed in detail. In addition, a comprehensive review of ophthalmic findings from prior reported cases of HMSN6A is provided. OBSERVATIONS HMSN6A is a neurologic disorder characterized by a motor sensory axonal neuropathy and optic atrophy. A range of additional ophthalmic manifestations have been reported in the literature. We highlight the proband and her sister who demonstrate this phenotype but also manifested other ocular abnormalities from an early age. In addition to optic nerve pallor, both sisters had additional ophthalmic features of bilateral pathologic myopia, limited vision, nystagmus, and strabismus. CONCLUSIONS AND IMPORTANCE This case series and review describe the ophthalmologic findings of HMSN6A and provides incentive to further investigate the correlation between molecular findings and the phenotype.
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Affiliation(s)
- Kevin Babu
- Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Kimberly Seamon
- Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,University of Florida College of Medicine, Jacksonville, Florida, USA
| | - Ann Jewell
- Department of Human and Molecular Genetics, Division of Clinical Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Anna Harrison
- Department of Ophthalmology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Amy Harper
- Department of Neurology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Hind Al Saif
- Department of Human and Molecular Genetics, Division of Clinical Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Natario Couser
- Department of Human and Molecular Genetics, Division of Clinical Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Department of Ophthalmology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Department of Pediatrics, Virginia Commonwealth University School of Medicine, Children's Hospital of Richmond at VCU, Richmond, Virginia, USA
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25
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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.
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Affiliation(s)
- Govinda Sharma
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, 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
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26
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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.
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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
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27
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Pozo Devoto VM, Onyango IG, Stokin GB. Mitochondrial behavior when things go wrong in the axon. Front Cell Neurosci 2022; 16:959598. [PMID: 35990893 PMCID: PMC9389222 DOI: 10.3389/fncel.2022.959598] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Axonal homeostasis is maintained by processes that include cytoskeletal regulation, cargo transport, synaptic activity, ionic balance, and energy supply. Several of these processes involve mitochondria to varying degrees. As a transportable powerplant, the mitochondria deliver ATP and Ca2+-buffering capabilities and require fusion/fission to maintain proper functioning. Taking into consideration the long distances that need to be covered by mitochondria in the axons, their transport, distribution, fusion/fission, and health are of cardinal importance. However, axonal homeostasis is disrupted in several disorders of the nervous system, or by traumatic brain injury (TBI), where the external insult is translated into physical forces that damage nervous tissue including axons. The degree of damage varies and can disconnect the axon into two segments and/or generate axonal swellings in addition to cytoskeletal changes, membrane leakage, and changes in ionic composition. Cytoskeletal changes and increased intra-axonal Ca2+ levels are the main factors that challenge mitochondrial homeostasis. On the other hand, a proper function and distribution of mitochondria can determine the recovery or regeneration of the axonal physiological state. Here, we discuss the current knowledge regarding mitochondrial transport, fusion/fission, and Ca2+ regulation under axonal physiological or pathological conditions.
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Affiliation(s)
- Victorio M. Pozo Devoto
- Translational Neuroscience and Ageing Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czechia
| | - Isaac G. Onyango
- Translational Neuroscience and Ageing Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czechia
| | - Gorazd B. Stokin
- Translational Neuroscience and Ageing Program, Centre for Translational Medicine, International Clinical Research Centre, St. Anne's University Hospital, Brno, Czechia
- Division of Neurology, University Medical Centre, Ljubljana, Slovenia
- Department of Neurosciences, Mayo Clinic, Rochester, MN, United States
- *Correspondence: Gorazd B. Stokin
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28
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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: 2] [Impact Index Per Article: 1.0] [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.
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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.
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29
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Kimura Y, Nishikawa A, Hashiguchi A, Etoh M, Yoshimura A, Asai K, Miyashita N, Takashima H, Sumi H, Naka T. An MFN2-related Charcot-Marie-Tooth Disease Patient with Optic Nerve Atrophy, Neurogenic Bladder Dysfunction, and Diaphragmatic Weakness. Intern Med 2022; 61:1743-1747. [PMID: 34803088 PMCID: PMC9259307 DOI: 10.2169/internalmedicine.6487-20] [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] [Indexed: 11/06/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is a common hereditary peripheral polyneuropathy encompassing distinct monogenetic disorders. Pathogenic mutations in mitofusin 2 (MFN2) are the most frequent cause of its axonal type, CMT type 2A, with diverse phenotypes. We herein report a Japanese patient with a novel heterozygous MFN2 pathogenic variant (c.740 G>C, p.R247P) and severe CMT phenotypes, including progressive muscle weakness, optic atrophy, urinary inconsistency, and restrictive pulmonary dysfunction with eventration of the diaphragm that developed over her 60-year disease course. Our case expands the clinico-genetic features of MFN2-related CMT and highlights the need to evaluate infrequent manifestations during long-term care of CMT patients.
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Affiliation(s)
- Yasuyoshi Kimura
- Department of Neurology, Higashiosaka City Medical Center, Japan
- Department of Neurology, Osaka University Graduate School of Medicine, Japan
| | - Akira Nishikawa
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Akihiro Hashiguchi
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | | | - Akiko Yoshimura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | - Kanako Asai
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Noriko Miyashita
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | - Hisae Sumi
- Department of Neurology, Higashiosaka City Medical Center, Japan
| | - Takashi Naka
- Department of Neurology, Higashiosaka City Medical Center, Japan
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30
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Abati E, Manini A, Velardo D, Del Bo R, Napoli L, Rizzo F, Moggio M, Bresolin N, Bellone E, Bassi MT, D'Angelo MG, Comi GP, Corti S. Clinical and genetic features of a cohort of patients with MFN2-related neuropathy. Sci Rep 2022; 12:6181. [PMID: 35418194 PMCID: PMC9008012 DOI: 10.1038/s41598-022-10220-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 04/05/2022] [Indexed: 11/09/2022] Open
Abstract
Charcot–Marie–Tooth disease type 2A (CMT2A) is a rare inherited axonal neuropathy caused by mutations in MFN2 gene, which encodes Mitofusin 2, a transmembrane protein of the outer mitochondrial membrane. We performed a cross-sectional analysis on thirteen patients carrying mutations in MFN2, from ten families, describing their clinical and genetic characteristics. Evaluated patients presented a variable age of onset and a wide phenotypic spectrum, with most patients presenting a severe phenotype. A novel heterozygous missense variant was detected, p.K357E. It is located at a highly conserved position and predicted as pathogenic by in silico tools. At a clinical level, the p.K357E carrier shows a severe sensorimotor axonal neuropathy. In conclusion, our work expands the genetic spectrum of CMT2A, disclosing a novel mutation and its related clinical effect, and provides a detailed description of the clinical features of a cohort of patients with MFN2 mutations. Obtaining a precise genetic diagnosis in affected families is crucial both for family planning and prenatal diagnosis, and in a therapeutic perspective, as we are entering the era of personalized therapy for genetic diseases.
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Affiliation(s)
- Elena Abati
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy. .,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
| | - Arianna Manini
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Daniele Velardo
- Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Roberto Del Bo
- Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Laura Napoli
- Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Federica Rizzo
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Maurizio Moggio
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Nereo Bresolin
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Emilia Bellone
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (Dinogmi) - Medical Genetics, University of Genoa, Genoa, Italy
| | - Maria Teresa Bassi
- Laboratory of Molecular Biology, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Maria Grazia D'Angelo
- Neuromuscular Disorder Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Giacomo Pietro Comi
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.,Neuromuscular and Rare Diseases Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Stefania Corti
- Department of Pathophysiology and Transplantation (DEPT), Dino Ferrari Centre, Neuroscience Section, Fondazione IRCCS Ca' Granda - Ospedale Maggiore Policlinico, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.,Neurology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
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31
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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: 24] [Impact Index Per Article: 12.0] [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.
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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,
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32
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Morikawa M, Jerath NU, Ogawa T, Morikawa M, Tanaka Y, Shy ME, Zuchner S, Hirokawa N. A neuropathy-associated kinesin KIF1A mutation hyper-stabilizes the motor-neck interaction during the ATPase cycle. EMBO J 2022; 41:e108899. [PMID: 35132656 PMCID: PMC8886545 DOI: 10.15252/embj.2021108899] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 12/21/2021] [Accepted: 12/22/2021] [Indexed: 11/09/2022] Open
Abstract
The mechanochemical coupling of ATPase hydrolysis and conformational dynamics in kinesin motors facilitates intramolecular interaction cycles between the kinesin motor and neck domains, which are essential for microtubule-based motility. Here, we characterized a charge-inverting KIF1A-E239K mutant that we identified in a family with axonal-type Charcot-Marie-Tooth disease and also in 24 cases in human neuropathies including spastic paraplegia and hereditary sensory and autonomic neuropathy. We show that Glu239 in the β7 strand is a key residue of the motor domain that regulates the motor-neck interaction. Expression of the KIF1A-E239K mutation has decreased ability to complement Kif1a+/- neurons, and significantly decreases ATPase activity and microtubule gliding velocity. X-ray crystallography shows that this mutation causes an excess positive charge on β7, which may electrostatically interact with a negative charge on the neck. Quantitative mass spectrometric analysis supports that the mutation hyper-stabilizes the motor-neck interaction at the late ATP hydrolysis stage. Thus, the negative charge of Glu239 dynamically regulates the kinesin motor-neck interaction, promoting release of the neck from the motor domain upon ATP hydrolysis.
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Affiliation(s)
- Manatsu Morikawa
- Department of Cell Biology and AnatomyGraduate School of MedicineThe University of TokyoTokyoJapan
| | - Nivedita U Jerath
- Department of NeurologyCarver College of MedicineUniversity of IowaIowa CityIAUSA,Neuromuscular DivisionAdventHealth OrlandoWinter ParkFLUSA
| | - Tadayuki Ogawa
- Department of Cell Biology and AnatomyGraduate School of MedicineThe University of TokyoTokyoJapan,Research Center for Advanced Medical ScienceDokkyo Medical UniversityMibuJapan
| | - Momo Morikawa
- Department of Cell Biology and AnatomyGraduate School of MedicineThe University of TokyoTokyoJapan,Department of Anatomy and NeuroscienceFaculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yosuke Tanaka
- Department of Cell Biology and AnatomyGraduate School of MedicineThe University of TokyoTokyoJapan
| | - Michael E Shy
- Department of NeurologyCarver College of MedicineUniversity of IowaIowa CityIAUSA
| | - Stephan Zuchner
- Department of Human Genetics and Hussman Institute for Human GenomicsMiller School of MedicineUniversity of MiamiMiamiFLUSA
| | - Nobutaka Hirokawa
- Department of Cell Biology and AnatomyGraduate School of MedicineThe University of TokyoTokyoJapan
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33
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Nagappa M, Sharma S, Govindaraj P, Chickabasaviah Y, Siram R, Shroti A, Seshagiri D, Debnath M, Bindu P, Taly A. Genetic spectrum of inherited neuropathies in India. Ann Indian Acad Neurol 2022; 25:407-416. [PMID: 35936615 PMCID: PMC9350795 DOI: 10.4103/aian.aian_269_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/29/2022] [Accepted: 04/30/2022] [Indexed: 11/17/2022] Open
Abstract
Background and Objectives: Charcot-Marie-Tooth (CMT) disease is the commonest inherited neuromuscular disorder and has heterogeneous manifestations. Data regarding genetic basis of CMT from India is limited. This study aims to report the variations by using high throughput sequencing in Indian CMT cohort. Methods: Fifty-five probands (M:F 29:26) with suspected inherited neuropathy underwent genetic testing (whole exome: 31, clinical exome: 17 and targeted panel: 7). Their clinical and genetic data were analysed. Results: Age at onset ranged from infancy to 54 years. Clinical features included early-onset neuropathy (n=23), skeletal deformities (n=45), impaired vision (n=8), impaired hearing (n=6), facial palsy (n=8), thickened nerves (n=4), impaired cognition (n=5), seizures (n=5), pyramidal signs (n=7), ataxia (n=8) and vocal cord palsy, slow tongue movements and psychosis in one patient each. Twenty-eight patients had demyelinating electrophysiology. Abnormal visual and auditory evoked potentials were noted in 60.60% and 37.5% respectively. Sixty two variants were identified in 37 genes including variants of uncertain significance (n=34) and novel variants (n=45). Eleven patients had additional variations in genes implicated in CMTs/ other neurological disorders. Ten patients did not have variations in neuropathy associated genes, but had variations in genes implicated in other neurological disorders. In seven patients, no variations were detected. Conclusion: In this single centre cohort study from India, genetic diagnosis could be established in 87% of patients with inherited neuropathy. The identified spectrum of genetic variations adds to the pool of existing data and provides a platform for validation studies in cell culture or animal model systems.
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34
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Motley W, Chaudry V, Lloyd TE. Treatment and Management of Hereditary Neuropathies. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00014-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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35
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Das R, Kamal IM, Das S, Chakrabarti S, Chakrabarti O. MITOL-mediated DRP1 ubiquitylation and degradation promotes mitochondrial hyperfusion in CMT2A-linked MFN2 mutant. J Cell Sci 2021; 135:273638. [PMID: 34870686 DOI: 10.1242/jcs.257808] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 11/29/2021] [Indexed: 11/20/2022] Open
Abstract
Mutations in Mitofusin2 (MFN2), associated with the pathology of the debilitating neuropathy, Charcot-Marie-Tooth type 2A (CMT2A) are known to alter mitochondrial morphology. One such abundant MFN2 mutant, R364W results in the generation of elongated, interconnected mitochondria. However, the mechanism leading to this mitochondrial aberration remains poorly understood. Here we show that mitochondrial hyperfusion in the presence of R364W-MFN2 is due to increased degradation of DRP1. The Ubiquitin E3 ligase MITOL is known to ubiquitylate both MFN2 and DRP1. Interaction with and its subsequent ubiquitylation by MITOL is stronger in presence of WT-MFN2 than R364W-MFN2. This differential interaction of MITOL with MFN2 in the presence of R364W-MFN2 renders the ligase more available for DRP1 ubiquitylation. Multimonoubiquitylation and proteasomal degradation of DRP1 in R364W-MFN2 cells in the presence of MITOL eventually leads to mitochondrial hyperfusion. Here we provide a mechanistic insight into mitochondrial hyperfusion, while also reporting that MFN2 can indirectly modulate DRP1 - an effect not shown before.
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Affiliation(s)
- Rajdeep Das
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata - 700064, India.,Homi Bhabha National Institute, India
| | - Izaz Monir Kamal
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, CN 6, Sector V, Salt Lake, Kolkata - 700091, India.,Academy of Scientific and Innovative Research (AcSIR), Gaziabad, India
| | - Subhrangshu Das
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, CN 6, Sector V, Salt Lake, Kolkata - 700091, India
| | - Saikat Chakrabarti
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, CN 6, Sector V, Salt Lake, Kolkata - 700091, India.,Academy of Scientific and Innovative Research (AcSIR), Gaziabad, India
| | - Oishee Chakrabarti
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata - 700064, India.,Homi Bhabha National Institute, India
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36
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Ma Y, Sun A, Zhang Y, Fan D, Liu X. The Genotype and Phenotype Features in a Large Chinese MFN2 Mutation Cohort. Front Neurol 2021; 12:757518. [PMID: 34721278 PMCID: PMC8548668 DOI: 10.3389/fneur.2021.757518] [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: 08/12/2021] [Accepted: 09/09/2021] [Indexed: 12/24/2022] Open
Abstract
Introduction: Charcot–Marie–Tooth disease type 2A (CMT2A) is a group of clinically and genetically heterogeneous disorders, which is mostly caused by mutations of the mitofusin2 (MFN2) gene. As the genotype–phenotype characteristics of CMT2A were still incompletely understood, we further explored the spectrum of CMT2A variants in China and demonstrated their phenotypic diversities. Methods: A total of 402 index patients/families with CMT throughout Mainland China were enrolled in this study. Among them, we analyzed 20 unrelated index cases with CMT2A by Sanger sequencing, next-generation sequencing, or whole-exome sequencing. Detailed clinical and genetic features of CMT2A patients were collected and analyzed. Of note, de novo mutations were not rare in MFN2 gene; we compared the clinical features of patients from the de novo group with those from the non-de novo group. Results: We identified 20 MFN2 variants, occupying 5.0% of CMT. Most patients presented with early onset and moderate phenotype with abnormal gait and foot drop as the main complaints at onset. Pyramidal signs accounts for 31.6% (6/19) in all patients, which is not uncommon. Four novel variants (p.Tyr752*, c.475-2A>G, p.Val99Met, and p.Arg275_Gln276insArg) were identified in the cohort. Besides, de novo variants occupied 35.0% (7/20) in our study with a much earlier age at onset compared with those in the non-de novo group (p = 0.021). Conclusion: Chinese CMT2A is a predominant typical pure CMT2A, with early onset and mild to moderate phenotype. Given the high frequency of de novo MFN2 mutations, genetic study should be considered for patients with early onset and severe idiopathic axonal neuropathy.
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Affiliation(s)
- Yan Ma
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Aping Sun
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Yingshuang Zhang
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Dongsheng Fan
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
| | - Xiaoxuan Liu
- Department of Neurology, Peking University Third Hospital, Beijing, China.,Beijing Municipal Key Laboratory of Biomarker and Translational Research in Neurodegenerative Diseases, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health Commission, Peking University, Beijing, China
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Kenvin S, Torregrosa-Muñumer R, Reidelbach M, Pennonen J, Turkia JJ, Rannila E, Kvist J, Sainio MT, Huber N, Herukka SK, Haapasalo A, Auranen M, Trokovic R, Sharma V, Ylikallio E, Tyynismaa H. Threshold of heteroplasmic truncating MT-ATP6 mutation in reprogramming, Notch hyperactivation and motor neuron metabolism. Hum Mol Genet 2021; 31:958-974. [PMID: 34635923 PMCID: PMC8947243 DOI: 10.1093/hmg/ddab299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/28/2021] [Accepted: 10/06/2021] [Indexed: 01/19/2023] Open
Abstract
Mutations in mitochondrial DNA encoded subunit of ATP synthase, MT-ATP6, are frequent causes of neurological mitochondrial diseases with a range of phenotypes from Leigh syndrome and NARP to ataxias and neuropathies. Here we investigated the functional consequences of an unusual heteroplasmic truncating mutation m.9154C>T in MT-ATP6, which caused peripheral neuropathy, ataxia and IgA nephropathy. ATP synthase not only generates cellular ATP, but its dimerization is required for mitochondrial cristae formation. Accordingly, the MT-ATP6 truncating mutation impaired the assembly of ATP synthase and disrupted cristae morphology, supporting our molecular dynamics simulations that predicted destabilized a/c subunit subcomplex. Next, we modeled the effects of the truncating mutation using patient-specific induced pluripotent stem cells. Unexpectedly, depending on mutation heteroplasmy level, the truncation showed multiple threshold effects in cellular reprogramming, neurogenesis and in metabolism of mature motor neurons (MN). Interestingly, MN differentiation beyond progenitor stage was impaired by Notch hyperactivation in the MT-ATP6 mutant, but not by rotenone-induced inhibition of mitochondrial respiration, suggesting that altered mitochondrial morphology contributed to Notch hyperactivation. Finally, we also identified a lower mutation threshold for a metabolic shift in mature MN, affecting lactate utilization, which may be relevant for understanding the mechanisms of mitochondrial involvement in peripheral motor neuropathies. These results establish a critical and disease-relevant role for ATP synthase in human cell fate decisions and neuronal metabolism.
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Affiliation(s)
- Sebastian Kenvin
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Ruben Torregrosa-Muñumer
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | | | - Jana Pennonen
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Jeremi J Turkia
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Erika Rannila
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Jouni Kvist
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Markus T Sainio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Nadine Huber
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Sanna-Kaisa Herukka
- Department of Neurology, Kuopio University Hospital, Kuopio, Finland.,Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Annakaisa Haapasalo
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Mari Auranen
- Clinical Neurosciences, Neurology, Helsinki University Hospital, Finland
| | - Ras Trokovic
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland
| | - Vivek Sharma
- Department of Physics, University of Helsinki, Finland.,HiLIFE Institute of Biotechnology, University of Helsinki, Finland
| | - Emil Ylikallio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland.,Clinical Neurosciences, Neurology, Helsinki University Hospital, Finland
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Finland.,Department of Medical and Clinical Genetics, University of Helsinki, Finland.,Neuroscience Center, HiLIFE, University of Helsinki, Finland
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Mou Y, Dein J, Chen Z, Jagdale M, Li XJ. MFN2 Deficiency Impairs Mitochondrial Transport and Downregulates Motor Protein Expression in Human Spinal Motor Neurons. Front Mol Neurosci 2021; 14:727552. [PMID: 34602978 PMCID: PMC8482798 DOI: 10.3389/fnmol.2021.727552] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/26/2021] [Indexed: 11/13/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is one of the most common genetically inherited neurological disorders and CMT type 2A (CMT 2A) is caused by dominant mutations in the mitofusin-2 (MFN2) gene. MFN2 is located in the outer mitochondrial membrane and is a mediator of mitochondrial fusion, with an essential role in maintaining normal neuronal functions. Although loss of MFN2 induces axonal neuropathy, the detailed mechanism by which MFN2 deficiency results in axonal degeneration of human spinal motor neurons remains largely unknown. In this study, we generated MFN2-knockdown human embryonic stem cell (hESC) lines using lentivirus expressing MFN2 short hairpin RNA (shRNA). Using these hESC lines, we found that MFN2 loss did not affect spinal motor neuron differentiation from hESCs but resulted in mitochondrial fragmentation and dysfunction as determined by live-cell imaging. Notably, MFN2-knockodwn spinal motor neurons exhibited CMT2A disease-related phenotypes, including extensive perikaryal inclusions of phosphorylated neurofilament heavy chain (pNfH), frequent axonal swellings, and increased pNfH levels in long-term cultures. Importantly, MFN2 deficit impaired anterograde and retrograde mitochondrial transport within axons, and reduced the mRNA and protein levels of kinesin and dynein, indicating the interfered motor protein expression induced by MFN2 deficiency. Our results reveal that MFN2 knockdown induced axonal degeneration of spinal motor neurons and defects in mitochondrial morphology and function. The impaired mitochondrial transport in MFN2-knockdown spinal motor neurons is mediated, at least partially, by the altered motor proteins, providing potential therapeutic targets for rescuing axonal degeneration of spinal motor neurons in CMT2A disease.
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Affiliation(s)
- Yongchao Mou
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, United States.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Joshua Dein
- MD Program, University of Illinois College of Medicine Rockford, Rockford, IL, United States
| | - Zhenyu Chen
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, United States.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Mrunali Jagdale
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, United States.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States
| | - Xue-Jun Li
- Department of Biomedical Sciences, University of Illinois College of Medicine Rockford, Rockford, IL, United States.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, United States
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39
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Pellino G, Faggioli R, Galuppi A, Leon A, Fusco C, Tugnoli V, Suppiej A. Mitofusin 2: The missing link between mtDNA maintenance defects and neurotransmitter disorders. Mitochondrion 2021; 61:159-164. [PMID: 34600155 DOI: 10.1016/j.mito.2021.09.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 09/01/2021] [Accepted: 09/27/2021] [Indexed: 02/07/2023]
Abstract
Mitofusin (MFN) 2 belongs to the large family of mitochondrial transmembrane GTPases and has a role in dynamic mitochondrial remodeling process governed by fusion and fission. MFN2 pathogenic variants classically cause Charcot-Marie-Tooth disease type 2A (CMT2A), the most common axonal form of CMT, but patients with complex and unusual phenotypes involving the central and peripheral nervous system have been described, with mitochondrial dysfunction proposed as the underlying pathogenic mechanism. Here, we report the first description of a neurochemical pattern of secondary alterations in the metabolism of biogenic amines linked to the de novo presence of the hotspot MFN2 pathogenic variant p.Arg104Trp. The infant presented a very early onset choreic movement disorder associated with severe axial hypotonia and fluctuating dystonia of limbs. The relationship between mitochondrial DNA (mtDNA) maintenance defects and dopaminergic neurotransmitter disorders, governed by MFN2, is discussed.
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Affiliation(s)
- Giuditta Pellino
- Pediatric Unit, Azienda USL Ferrara - Sant'Anna University Hospital of Ferrara, Ferrara, Italy.
| | - Raffaella Faggioli
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
| | - Anna Galuppi
- Child Neurology Unit, Azienda USL Ferrara, Ferrara, Italy
| | - Alberta Leon
- Research & Innovation Srl (R&I Genetics), Padova, Italy
| | - Carlo Fusco
- Child Neurology and Psychiatric Unit-Presidio Ospedaliero Santa Maria Nuova - AUSL - IRCCS of Reggio Emilia, Reggio Emilia, Italy
| | - Valeria Tugnoli
- Department of Neuroscience and Rehabilitation, Division of Neurology, Sant'Anna University Hospital of Ferrara, Ferrara, Italy
| | - Agnese Suppiej
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
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40
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Cavallaro T, Tagliapietra M, Fabrizi GM, Bai Y, Shy ME, Vallat JM. Hereditary neuropathies: A pathological perspective. J Peripher Nerv Syst 2021; 26 Suppl 2:S42-S60. [PMID: 34499384 DOI: 10.1111/jns.12467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/30/2021] [Accepted: 08/24/2021] [Indexed: 12/29/2022]
Abstract
Hereditary neuropathies may result from mutations in genes expressed by Schwann cells or neurons that affect selectively the peripheral nervous system (PNS) or may represent a minor or major component of complex inherited diseases that involve also the central nervous system and/or other organs and tissues. The chapter is constantly expanding and reworking, thanks to advances of molecular genetics; next-generation sequencing is identifying a plethora of new genes and is revolutionizing the diagnostic approach. In the past, diagnostic sural nerve biopsies paved the way to the discovery and elucidation of major genes and molecular pathways associated to most frequent hereditary motor-sensory neuropathies. Nowadays, a sural nerve biopsy may prove useful in selected cases for the differential diagnosis of an acquired neuropathy when clinical examination, nerve conduction studies, and molecular tests are not sufficiently informative. Skin biopsy has emerged as a minimally invasive window on the PNS, which may provide biomarkers of progression and clues to the physiopathology and molecular pathology of inherited neuropathies. The aim of our review is to illustrate the pathological features of more frequent and paradigmatic hereditary neuropathies and to highlight their correlations with the roles of the involved genes and functional consequences of related molecular defects.
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Affiliation(s)
- Tiziana Cavallaro
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, VR, Italy
| | - Matteo Tagliapietra
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, VR, Italy
| | - Gian Maria Fabrizi
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, VR, Italy
| | - Yunhong Bai
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Jean-Michel Vallat
- Department of Neurology, National Reference Center for "Rare Peripheral Neuropathies", CHU Dupuytren, Limoges, France
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41
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Wu R, Lv H, Wang H, Wang Z, Yuan Y. The Pathological Features of Common Hereditary Mitochondrial Dynamics Neuropathy. Front Neurosci 2021; 15:705277. [PMID: 34366782 PMCID: PMC8341155 DOI: 10.3389/fnins.2021.705277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 06/28/2021] [Indexed: 01/02/2023] Open
Abstract
Objectives Mitofusin 2 and ganglioside-induced differentiation-associated protein 1 are two main mitochondrial dynamics-related proteins. Dysfunction of these two proteins leads to different subtypes of Charcot–Marie–Tooth disease type 2A (CMT2A) and CMT2K. This study aims to report the pathological difference between CMT2A and CMT2K in a large cohort. Methods Thirty patients with molecularly confirmed CMT2A and nine with CMT2K were identified by next-generation sequencing. Sural nerve biopsies were performed in 29 patients. Results The patients with both diseases showed length-dependent neuropathy with distal weakness, sensory loss, and no deep tendon reflex. Optic neuropathy appeared in 3/30 (10%) patients with CMT2A. Tendon contracture appeared in 4/9 (50.0%) patients with CMT2K. Sural biopsy revealed the loss of both myelinated and unmyelinated nerve fibers. Closely packed, irregularly oriented neurofilaments were observed in axons of unmyelinated nerve fibers in both diseases. Another important finding was the ubiquitous presence of smaller, rounded, and fragmented mitochondria in CMT2A and elongated mitochondria in CMT2K in the myelinated and unmyelinated axons. Conclusion This study confirmed large diversity in phenotypes between CMT2A and CMT2K. Mitochondrial dynamics-related variations can induce different mitochondrial morphological changes and neurofilament accumulation in axons.
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Affiliation(s)
- Rui Wu
- Department of Neurology, Peking University First Hospital, Beijing, China.,Department of Neurology, Shandong Provincial Hospital, Shandong University, Jinan, China
| | - He Lv
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Hui Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
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42
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Ferese R, Campopiano R, Scala S, D'Alessio C, Storto M, Buttari F, Centonze D, Logroscino G, Zecca C, Zampatti S, Fornai F, Cianci V, Manfroi E, Giardina E, Magnani M, Suppa A, Novelli G, Gambardella S. Cohort Analysis of 67 Charcot-Marie-Tooth Italian Patients: Identification of New Mutations and Broadening of Phenotype Expression Produced by Rare Variants. Front Genet 2021; 12:682050. [PMID: 34354735 PMCID: PMC8329958 DOI: 10.3389/fgene.2021.682050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 06/17/2021] [Indexed: 11/13/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is the most prevalent inherited motor sensory neuropathy, which clusters a clinically and genetically heterogeneous group of disorders with more than 90 genes associated with different phenotypes. The goal of this study is to identify the genetic features in the recruited cohort of patients, highlighting the role of rare variants in the genotype-phenotype correlation. We enrolled 67 patients and applied a diagnostic protocol including multiple ligation-dependent probe amplification for copy number variation (CNV) detection of PMP22 locus, and next-generation sequencing (NGS) for sequencing of 47 genes known to be associated with CMT and routinely screened in medical genetics. This approach allowed the identification of 26 patients carrying a whole gene CNV of PMP22. In the remaining 41 patients, NGS identified the causative variants in eight patients in the genes HSPB1, MFN2, KIF1A, GDAP1, MTMR2, SH3TC2, KIF5A, and MPZ (five new vs. three previously reported variants; three sporadic vs. five familial variants). Familial segregation analysis allowed to correctly interpret two variants, initially reported as "variants of uncertain significance" but re-classified as pathological. In this cohort is reported a patient carrying a novel familial mutation in the tail domain of KIF5A [a protein domain previously associated with familial amyotrophic lateral sclerosis (ALS)], and a CMT patient carrying a HSPB1 mutation, previously reported in ALS. These data indicate that combined tools for gene association in medical genetics allow dissecting unexpected phenotypes associated with previously known or unknown genotypes, thus broadening the phenotype expression produced by either pathogenic or undefined variants. Clinical trial registration: ClinicalTrials.gov (NCT03084224).
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Affiliation(s)
| | | | | | | | | | | | - Diego Centonze
- IRCCS Neuromed, Pozzilli, Italy.,Laboratory of Synaptic Immunopathology, Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Giancarlo Logroscino
- Center for Neurodegenerative Diseases and the Aging Brain, Department of Clinical Research in Neurology, The University of Bari "Aldo Moro," "Pia Fondazione Card G. Panico" Hospital Tricase, Lecce, Italy.,Department of Basic Medicine Neuroscience and Sense Organs, University "Aldo Moro" Bari, Bari, Italy
| | - Chiara Zecca
- Center for Neurodegenerative Diseases and the Aging Brain, Department of Clinical Research in Neurology, The University of Bari "Aldo Moro," "Pia Fondazione Card G. Panico" Hospital Tricase, Lecce, Italy
| | - Stefania Zampatti
- IRCCS Neuromed, Pozzilli, Italy.,Genomic Medicine Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Francesco Fornai
- IRCCS Neuromed, Pozzilli, Italy.,Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Vittoria Cianci
- Regional Epilepsy Centre, Great Metropolitan Hospital Bianchi-Melacrino-Morelli, Reggio Calabria, Italy
| | - Elisabetta Manfroi
- Department of Neuroscience- Neurogenetics, Santa Maria Hospital, Terni, Italy
| | - Emiliano Giardina
- Genomic Medicine Laboratory, IRCCS Fondazione Santa Lucia, Rome, Italy.,Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Rome, Italy
| | - Mauro Magnani
- Department of Biomolecular Sciences, University of Urbino "Carlo Bo," Urbino, Italy
| | - Antonio Suppa
- IRCCS Neuromed, Pozzilli, Italy.,Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Giuseppe Novelli
- IRCCS Neuromed, Pozzilli, Italy.,Department of Biomedicine and Prevention, University of Rome "Tor Vergata," Rome, Italy
| | - Stefano Gambardella
- IRCCS Neuromed, Pozzilli, Italy.,Department of Biomolecular Sciences, University of Urbino "Carlo Bo," Urbino, Italy
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43
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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.
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44
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Paß T, Wiesner RJ, Pla-Martín D. Selective Neuron Vulnerability in Common and Rare Diseases-Mitochondria in the Focus. Front Mol Biosci 2021; 8:676187. [PMID: 34295920 PMCID: PMC8290884 DOI: 10.3389/fmolb.2021.676187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/08/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial dysfunction is a central feature of neurodegeneration within the central and peripheral nervous system, highlighting a strong dependence on proper mitochondrial function of neurons with especially high energy consumptions. The fitness of mitochondria critically depends on preservation of distinct processes, including the maintenance of their own genome, mitochondrial dynamics, quality control, and Ca2+ handling. These processes appear to be differently affected in common neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease, as well as in rare neurological disorders, including Huntington’s disease, Amyotrophic Lateral Sclerosis and peripheral neuropathies. Strikingly, particular neuron populations of different morphology and function perish in these diseases, suggesting that cell-type specific factors contribute to the vulnerability to distinct mitochondrial defects. Here we review the disruption of mitochondrial processes in common as well as in rare neurological disorders and its impact on selective neurodegeneration. Understanding discrepancies and commonalities regarding mitochondrial dysfunction as well as individual neuronal demands will help to design new targets and to make use of already established treatments in order to improve treatment of these diseases.
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Affiliation(s)
- Thomas Paß
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, University of Cologne, Cologne, Germany
| | - Rudolf J Wiesner
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - David Pla-Martín
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, University of Cologne, Cologne, Germany
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45
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Tur J, Pereira-Lopes S, Vico T, Marín EA, Muñoz JP, Hernández-Alvarez M, Cardona PJ, Zorzano A, Lloberas J, Celada A. Mitofusin 2 in Macrophages Links Mitochondrial ROS Production, Cytokine Release, Phagocytosis, Autophagy, and Bactericidal Activity. Cell Rep 2021; 32:108079. [PMID: 32846136 DOI: 10.1016/j.celrep.2020.108079] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 07/02/2020] [Accepted: 08/05/2020] [Indexed: 12/27/2022] Open
Abstract
Mitofusin 2 (Mfn2) plays a major role in mitochondrial fusion and in the maintenance of mitochondria-endoplasmic reticulum contact sites. Given that macrophages play a major role in inflammation, we studied the contribution of Mfn2 to the activity of these cells. Pro-inflammatory stimuli such as lipopolysaccharide (LPS) induced Mfn2 expression. The use of the Mfn2 and Mfn1 myeloid-conditional knockout (KO) mouse models reveals that Mfn2 but not Mfn1 is required for the adaptation of mitochondrial respiration to stress conditions and for the production of reactive oxygen species (ROS) upon pro-inflammatory activation. Mfn2 deficiency specifically impairs the production of pro-inflammatory cytokines and nitric oxide. In addition, the lack of Mfn2 but not Mfn1 is associated with dysfunctional autophagy, apoptosis, phagocytosis, and antigen processing. Mfn2floxed;CreLysM mice fail to be protected from Listeria, Mycobacterium tuberculosis, or LPS endotoxemia. These results reveal an unexpected contribution of Mfn2 to ROS production and inflammation in macrophages.
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Affiliation(s)
- Juan Tur
- Macrophage Biology Group, Department of Cell Biology, Physiology and Immunology, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Selma Pereira-Lopes
- Macrophage Biology Group, Department of Cell Biology, Physiology and Immunology, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Tania Vico
- Macrophage Biology Group, Department of Cell Biology, Physiology and Immunology, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Eros A Marín
- Macrophage Biology Group, Department of Cell Biology, Physiology and Immunology, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Juan P Muñoz
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 08036 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain; Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Maribel Hernández-Alvarez
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 08036 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain; Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Pere-Joan Cardona
- Unitat de tuberculosi experimental, Institut Germans Trias i Pujol, Badalona, Spain
| | - Antonio Zorzano
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 08036 Barcelona, Spain; Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Spain; Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Jorge Lloberas
- Macrophage Biology Group, Department of Cell Biology, Physiology and Immunology, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
| | - Antonio Celada
- Macrophage Biology Group, Department of Cell Biology, Physiology and Immunology, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
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46
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Adebayo M, Singh S, Singh AP, Dasgupta S. Mitochondrial fusion and fission: The fine-tune balance for cellular homeostasis. FASEB J 2021; 35:e21620. [PMID: 34048084 PMCID: PMC8415099 DOI: 10.1096/fj.202100067r] [Citation(s) in RCA: 159] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/06/2021] [Accepted: 04/10/2021] [Indexed: 12/13/2022]
Abstract
Mitochondria are highly dynamic, maternally inherited cytoplasmic organelles, which fulfill cellular energy demand through the oxidative phosphorylation system. Besides, they play an active role in calcium and damage-associated molecular patterns signaling, amino acid, and lipid metabolism, and apoptosis. Thus, the maintenance of mitochondrial integrity and homeostasis is extremely critical, which is achieved through continual fusion and fission. Mitochondrial fusion allows the transfer of gene products between mitochondria for optimal functioning, especially under metabolic and environmental stress. On the other hand, fission is crucial for mitochondrial division and quality control. The imbalance between these two processes is associated with various ailments such as cancer, neurodegenerative and cardiovascular diseases. This review discusses the molecular mechanisms that control mitochondrial fusion and fission and how the disruption of mitochondrial dynamics manifests into various disease conditions.
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Affiliation(s)
- Mary Adebayo
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL 36617
| | - Seema Singh
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL 36617
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688
| | - Ajay Pratap Singh
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL 36617
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688
| | - Santanu Dasgupta
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604
- Department of Pathology, College of Medicine, University of South Alabama, Mobile, AL 36617
- Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688
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47
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Abstract
BACKGROUND Charcot-Marie-Tooth disease Type 2A (CMT2A) presents with optic atrophy in a subset of patients, but the prevalence and severity of optic nerve involvement in relation to other CMT subtypes has not been explored. METHODS Patients with genetically confirmed CMT2A (n = 5), CMT1A (n = 9) and CMTX1 (n = 10) underwent high- and low-contrast acuity testing using Sloan letter charts, and circumpapillary retinal nerve fiber layer (RNFL) and macular total retinal, RNFL, and ganglion cell layer/inner plexiform layer thickness was measured using spectral domain optical coherence tomography (OCT). We used age- and gender-adjusted linear regression to compare contrast acuity and retinal thickness between CMT groups. RESULTS One of 5 patients with CMT2A had optic nerve atrophy (binocular high-contrast acuity equivalent 20/160, mean circumpapillary RNFL 47.5 μm). The other patients with CMT2A had normal high- and low-contrast acuity and retinal thickness, and there were no significant differences between patients with CMT2A, CMT1A, and CMTX1. CONCLUSIONS Optic atrophy occurs in some patients with CMT2A, but in others, there is no discernible optic nerve involvement. This suggests that optic neuropathy is specific to certain MFN2 mutations in CMT2A and that low-contrast acuity or OCT is of limited value as a disease-wide biomarker.
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Affiliation(s)
- Ali G Hamedani
- Department of Neurology (AGH, JAW, RAA, SSS), Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Translational Center of Excellence for Neuroepidemiology and Neurology Outcomes Research (AGH), University of Pennsylvania, Philadelphia, Pennsylvania; Center for Clinical Epidemiology and Biostatistics (AGH), University of Pennsylvania, Philadelphia, Pennsylvania; Department of Ophthalmology (RAA), Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and Division of Ophthalmology (RAA), Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
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48
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Pipis M, Feely SME, Polke JM, Skorupinska M, Perez L, Shy RR, Laura M, Morrow JM, Moroni I, Pisciotta C, Taroni F, Vujovic D, Lloyd TE, Acsadi G, Yum SW, Lewis RA, Finkel RS, Herrmann DN, Day JW, Li J, Saporta M, Sadjadi R, Walk D, Burns J, Muntoni F, Ramchandren S, Horvath R, Johnson NE, Züchner S, Pareyson D, Scherer SS, Rossor AM, Shy ME, Reilly MM. Natural history of Charcot-Marie-Tooth disease type 2A: a large international multicentre study. Brain 2021; 143:3589-3602. [PMID: 33415332 PMCID: PMC7805791 DOI: 10.1093/brain/awaa323] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/28/2020] [Indexed: 01/02/2023] Open
Abstract
Mitofusin-2 (MFN2) is one of two ubiquitously expressed homologous proteins in eukaryote cells, playing a critical role in mitochondrial fusion. Mutations in MFN2 (most commonly autosomal dominant) cause Charcot-Marie-Tooth disease type 2A (CMT2A), the commonest axonal form of CMT, with significant allelic heterogeneity. Previous, moderately-sized, cross sectional genotype-phenotype studies of CMT2A have described the phenotypic spectrum of the disease, but longitudinal natural history studies are lacking. In this large multicentre prospective cohort study of 196 patients with dominant and autosomal recessive CMT2A, we present an in-depth genotype-phenotype study of the baseline characteristics of patients with CMT2A and longitudinal data (1–2 years) to describe the natural history. A childhood onset of autosomal dominant CMT2A is the most predictive marker of significant disease severity and is independent of the disease duration. When compared to adult onset autosomal dominant CMT2A, it is associated with significantly higher rates of use of ankle-foot orthoses, full-time use of wheelchair, dexterity difficulties and also has significantly higher CMT Examination Score (CMTESv2) and CMT Neuropathy Score (CMTNSv2) at initial assessment. Analysis of longitudinal data using the CMTESv2 and its Rasch-weighted counterpart, CMTESv2-R, show that over 1 year, the CMTESv2 increases significantly in autosomal dominant CMT2A (mean change 0.84 ± 2.42; two-tailed paired t-test P = 0.039). Furthermore, over 2 years both the CMTESv2 (mean change 0.97 ± 1.77; two-tailed paired t-test P = 0.003) and the CMTESv2-R (mean change 1.21 ± 2.52; two-tailed paired t-test P = 0.009) increase significantly with respective standardized response means of 0.55 and 0.48. In the paediatric CMT2A population (autosomal dominant and autosomal recessive CMT2A grouped together), the CMT Pediatric Scale increases significantly both over 1 year (mean change 2.24 ± 3.09; two-tailed paired t-test P = 0.009) and over 2 years (mean change 4.00 ± 3.79; two-tailed paired t-test P = 0.031) with respective standardized response means of 0.72 and 1.06. This cross-sectional and longitudinal study of the largest CMT2A cohort reported to date provides guidance for variant interpretation, informs prognosis and also provides natural history data that will guide clinical trial design.
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Affiliation(s)
- Menelaos Pipis
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Shawna M E Feely
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - James M Polke
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Mariola Skorupinska
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Laura Perez
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Rosemary R Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Matilde Laura
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Jasper M Morrow
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Isabella Moroni
- Department of Pediatric Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Pisciotta
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Franco Taroni
- Unit of Medical Genetics and Neurogenetics, Department of Diagnostics and Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Dragan Vujovic
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Thomas E Lloyd
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Gyula Acsadi
- Connecticut Children's Medical Center, Hartford, CT, USA
| | - Sabrina W Yum
- The Children's Hospital of Philadelphia, and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Richard A Lewis
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Richard S Finkel
- Center for Experimental Neurotherapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - David N Herrmann
- Department of Neurology, University of Rochester, Rochester, NY, USA
| | - John W Day
- Department of Neurology, Stanford Health Care, Stanford, CA, USA
| | - Jun Li
- Department of Neurology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Mario Saporta
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Reza Sadjadi
- Massachusetts General Hospital, Boston, Massachusetts, USA
| | - David Walk
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Joshua Burns
- University of Sydney School of Health Sciences and Children's Hospital at Westmead, Sydney, Australia
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, NIHR Biomedical Research Centre at UCL Great Ormond Street Institute of Child Health and Great Ormond Street Hospital, London, UK
| | | | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | | | - Stephan Züchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Davide Pareyson
- Unit of Rare Neurodegenerative and Neurometabolic Diseases, Department of Clinical Neurosciences, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Steven S Scherer
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander M Rossor
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, UK
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49
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Navaratnarajah T, Anand R, Reichert AS, Distelmaier F. The relevance of mitochondrial morphology for human disease. Int J Biochem Cell Biol 2021; 134:105951. [PMID: 33610749 DOI: 10.1016/j.biocel.2021.105951] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/01/2021] [Accepted: 02/03/2021] [Indexed: 12/18/2022]
Abstract
Mitochondria are highly dynamic organelles, which undergo frequent structural and metabolic changes to fulfil cellular demands. To facilitate these processes several proteins are required to regulate mitochondrial shape and interorganellar communication. These proteins include the classical mitochondrial fusion (MFN1, MFN2, and OPA1) and fission proteins (DRP1, MFF, FIS1, etc.) as well as several other proteins that are directly or indirectly involved in these processes (e.g. YME1L, OMA1, INF2, GDAP1, MIC13, etc.). During the last two decades, inherited genetic defects in mitochondrial fusion and fission proteins have emerged as an important class of neurodegenerative human diseases with variable onset ranging from infancy to adulthood. So far, no causal treatment strategies are available for these disorders. In this review, we provide an overview about the current knowledge on mitochondrial dynamics under physiological conditions. Moreover, we describe human diseases, which are associated with genetic defects in these pathways.
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Affiliation(s)
- Tharsini Navaratnarajah
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Ruchika Anand
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich-Heine-University-Düsseldorf, Düsseldorf, Germany
| | - Andreas S Reichert
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich-Heine-University-Düsseldorf, Düsseldorf, Germany
| | - Felix Distelmaier
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
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50
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Di Nottia M, Verrigni D, Torraco A, Rizza T, Bertini E, Carrozzo R. Mitochondrial Dynamics: Molecular Mechanisms, Related Primary Mitochondrial Disorders and Therapeutic Approaches. Genes (Basel) 2021; 12:genes12020247. [PMID: 33578638 PMCID: PMC7916359 DOI: 10.3390/genes12020247] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 02/06/2023] Open
Abstract
Mitochondria do not exist as individual entities in the cell—conversely, they constitute an interconnected community governed by the constant and opposite process of fission and fusion. The mitochondrial fission leads to the formation of smaller mitochondria, promoting the biogenesis of new organelles. On the other hand, following the fusion process, mitochondria appear as longer and interconnected tubules, which enhance the communication with other organelles. Both fission and fusion are carried out by a small number of highly conserved guanosine triphosphatase proteins and their interactors. Disruption of this equilibrium has been associated with several pathological conditions, ranging from cancer to neurodegeneration, and mutations in genes involved in mitochondrial fission and fusion have been reported to be the cause of a subset of neurogenetic disorders.
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