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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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Singh S, Bruder-Nascimento A, Costa RM, Alves JV, Bharathi S, Goetzman ES, Bruder-Nascimento T. Adjusted vascular contractility relies on integrity of progranulin pathway: Insights into mitochondrial function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.27.564485. [PMID: 37961631 PMCID: PMC10634918 DOI: 10.1101/2023.10.27.564485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Objective Cardiovascular disease (CVD) is a global health crisis and a leading cause of mortality. The intricate interplay between vascular contractility and mitochondrial function is central to CVD pathogenesis. The progranulin gene (GRN) encodes glycoprotein progranulin (PGRN), a ubiquitous molecule with known anti-inflammatory property. However, the role of PGRN in CVD remains enigmatic. In this study, we sought to dissect the significance of PGRN in the regulation vascular contractility and investigate the interface between PGRN and mitochondrial quality. Method Our investigation utilized aortae from male and female C57BL6/J wild-type (PGRN+/+) and B6(Cg)-Grntm1.1Aidi/J (PGRN-/-) mice, encompassing wire myograph assays to assess vascular contractility and primary aortic vascular smooth muscle cells (VSMCs) for mechanistic insights. Results Our results showed suppression of contractile activity in PGRN-/- VSMCs and aorta, followed by reduced α-smooth muscle actin expression. Mechanistically, PGRN deficiency impaired mitochondrial oxygen consumption rate (OCR), complex I activity, mitochondrial turnover, and mitochondrial redox signaling, while restoration of PGRN levels in aortae from PGRN-/- mice via lentivirus delivery ameliorated contractility and boosted OCR. In addition, VSMC overexpressing PGRN displayed higher mitochondrial respiration and complex I activity accompanied by cellular hypercontractility. Furthermore, increased PGRN triggered lysosome biogenesis by regulating transcription factor EB and accelerated mitophagy flux in VSMC, while treatment with spermidine, an autophagy inducer, improved mitochondrial phenotype and enhanced vascular contractility. Finally, angiotensin II failed to induce vascular contractility in PGRN-/- suggesting a key role of PGRN to maintain the vascular tone. Conclusion Our findings suggest that PGRN preserves the vascular contractility via regulating mitophagy flux, mitochondrial complex I activity, and redox signaling. Therefore, loss of PGRN function appears as a pivotal risk factor in CVD development.
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Affiliation(s)
- Shubhnita Singh
- Department of Pediatrics at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Pediatrics Research in Obesity and Metabolism (CPROM) at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Endocrinology Division at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, USA
| | - Ariane Bruder-Nascimento
- Department of Pediatrics at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Pediatrics Research in Obesity and Metabolism (CPROM) at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Endocrinology Division at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rafael M Costa
- Department of Pediatrics at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Pediatrics Research in Obesity and Metabolism (CPROM) at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Endocrinology Division at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Juliano V Alves
- Department of Pediatrics at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Pediatrics Research in Obesity and Metabolism (CPROM) at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Endocrinology Division at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Pharmacology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, SP, Brazil
| | - Sivakama Bharathi
- Department of Pediatrics at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
| | - Eric S Goetzman
- Department of Pediatrics at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, USA
- Genetic and Genomic Medicine Division at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
| | - Thiago Bruder-Nascimento
- Department of Pediatrics at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Pediatrics Research in Obesity and Metabolism (CPROM) at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Endocrinology Division at UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
- Vascular Medicine Institute (VMI), University of Pittsburgh, Pittsburgh, PA, USA
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Dang X, Zhang L, Franco A, Dorn II GW. Activating mitofusins interrupts mitochondrial degeneration and delays disease progression in SOD1 mutant amyotrophic lateral sclerosis. Hum Mol Genet 2023; 32:1208-1222. [PMID: 36416308 PMCID: PMC10026224 DOI: 10.1093/hmg/ddac287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/25/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022] Open
Abstract
Mitochondrial involvement in neurodegenerative diseases is widespread and multifactorial. Targeting mitochondrial pathology is therefore of interest. The recent development of bioactive molecules that modulate mitochondrial dynamics (fusion, fission and motility) offers a new therapeutic approach for neurodegenerative diseases with either indirect or direct mitochondrial involvement. Here, we asked: (1) Can enhanced mitochondrial fusion and motility improve secondary mitochondrial pathology in superoxide dismutase1 (SOD1) mutant amyotrophic lateral sclerosis (ALS)? And: (2) What is the impact of enhancing mitochondria fitness on in vivo manifestations of SOD1 mutant ALS? We observed that small molecule mitofusin activators corrected mitochondrial fragmentation, depolarization and dysmotility in genetically diverse ALS patient reprogrammed motor neurons and fibroblasts, and in motor neurons, sensory neurons and fibroblasts from SOD1 G93A mice. Continuous, but not intermittent, pharmacologic mitofusin activation delayed phenotype progression and lethality in SOD1 G93A mice, reducing neuron loss and improving neuromuscular connectivity. Mechanistically, mitofusin activation increased mitochondrial motility, fitness and residency within neuromuscular synapses; reduced mitochondrial reactive oxygen species production; and diminished apoptosis in SOD1 mutant neurons. These benefits were accompanied by improved mitochondrial respiratory coupling, despite characteristic SOD1 mutant ALS-associated downregulation of mitochondrial respiratory complexes. Targeting mitochondrial dysdynamism is a promising approach to alleviate pathology caused by secondary mitochondrial dysfunction in some neurodegenerative diseases.
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Affiliation(s)
- Xiawei Dang
- Department of Internal Medicine, Washington University School of Medicine, St. Louis MO USA
- Department of Psychiatry, The First Affiliated Hospital of Xi’an Jiao Tong University, Xi’an, Shaanxi 710061, China
| | - Lihong Zhang
- Department of Internal Medicine, Washington University School of Medicine, St. Louis MO USA
| | - Antonietta Franco
- Department of Internal Medicine, Washington University School of Medicine, St. Louis MO USA
| | - Gerald W Dorn II
- Department of Internal Medicine, Washington University School of Medicine, St. Louis MO USA
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Rybkowska P, Radoszkiewicz K, Kawalec M, Dymkowska D, Zabłocka B, Zabłocki K, Sarnowska A. The Metabolic Changes between Monolayer (2D) and Three-Dimensional (3D) Culture Conditions in Human Mesenchymal Stem/Stromal Cells Derived from Adipose Tissue. Cells 2023; 12:cells12010178. [PMID: 36611971 PMCID: PMC9818744 DOI: 10.3390/cells12010178] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/22/2022] [Accepted: 12/30/2022] [Indexed: 01/03/2023] Open
Abstract
INTRODUCTION One of the key factors that may influence the therapeutic potential of mesenchymal stem/stromal cells (MSCs) is their metabolism. The switch between mitochondrial respiration and glycolysis can be affected by many factors, including the oxygen concentration and the spatial form of culture. This study compared the metabolic features of adipose-derived mesenchymal stem/stromal cells (ASCs) and dedifferentiated fat cells (DFATs) cultivated as monolayer or spheroid culture under 5% O2 concentration (physiological normoxia) and their impact on MSCs therapeutic abilities. RESULTS We observed that the cells cultured as spheroids had a slightly lower viability and a reduced proliferation rate but a higher expression of the stemness-related transcriptional factors compared to the cells cultured in monolayer. The three-dimensional culture form increased mtDNA content, oxygen consumption rate (OCR) and extracellular acidification rate (ECAR), especially in DFATs-3D population. The DFATs spheroids also demonstrated increased levels of Complex V proteins and higher rates of ATP production. Moreover, increased reactive oxygen species and lower intracellular lactic acid levels were also found in 3D culture. CONCLUSION Our results may suggest that metabolic reconfiguration accompanies the transition from 2D to 3D culture and the processes of both mitochondrial respiration and glycolysis become more active. Intensified metabolism might be associated with the increased demand for energy, which is needed to maintain the expression of pluripotency genes and stemness state.
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Affiliation(s)
- Paulina Rybkowska
- Translational Platform for Regenerative Medicine, Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Klaudia Radoszkiewicz
- Translational Platform for Regenerative Medicine, Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Maria Kawalec
- Molecular Biology Unit, Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Dorota Dymkowska
- Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Science, 02-093 Warsaw, Poland
| | - Barbara Zabłocka
- Molecular Biology Unit, Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Krzysztof Zabłocki
- Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Science, 02-093 Warsaw, Poland
| | - Anna Sarnowska
- Translational Platform for Regenerative Medicine, Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland
- Correspondence: ; Tel.: +48-22-608-6598
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5
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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: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/07/2022] [Indexed: 12/17/2022] Open
Abstract
The Mitofusin 2 protein (MFN2), encoded by the MFN2 gene, was first described for its role in mediating mitochondrial fusion. However, MFN2 is now recognized to play additional roles in mitochondrial autophagy (mitophagy), mitochondrial motility, lipid transfer, and as a tether to other organelles including the endoplasmic reticulum (ER) and lipid droplets. The tethering role of MFN2 is an important mediator of mitochondrial-ER contact sites (MERCs), which themselves have many important functions that regulate mitochondria, including calcium homeostasis and lipid metabolism. Exemplifying the importance of MFN2, pathogenic variants in MFN2 are established to cause the peripheral neuropathy Charcot-Marie-Tooth Disease Subtype 2A (CMT2A). However, the mechanistic basis for disease is not clear. Moreover, additional pathogenic phenotypes such as lipomatosis, distal myopathy, optic atrophy, and hearing loss, can also sometimes be present in patients with CMT2A. Given these variable patient phenotypes, and the many cellular roles played by MFN2, the mechanistic underpinnings of the cellular impairments by which MFN2 dysfunction leads to disease are likely to be complex. Here, we will review what is known about the various functions of MFN2 that are impaired by pathogenic variants causing CMT2A, with a specific emphasis on the ties between MFN2 variants and MERCs.
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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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Dang X, Walton EK, Zablocka B, Baloh RH, Shy ME, Dorn GW. Mitochondrial Phenotypes in Genetically Diverse Neurodegenerative Diseases and Their Response to Mitofusin Activation. Cells 2022; 11:cells11061053. [PMID: 35326504 PMCID: PMC8947610 DOI: 10.3390/cells11061053] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/08/2022] [Accepted: 03/16/2022] [Indexed: 01/27/2023] Open
Abstract
Mitochondrial fusion is essential to mitochondrial fitness and cellular health. Neurons of patients with genetic neurodegenerative diseases often exhibit mitochondrial fragmentation, reflecting an imbalance in mitochondrial fusion and fission (mitochondrial dysdynamism). Charcot–Marie–Tooth (CMT) disease type 2A is the prototypical disorder of impaired mitochondrial fusion caused by mutations in the fusion protein mitofusin (MFN)2. Yet, cultured CMT2A patient fibroblast mitochondria are often reported as morphologically normal. Metabolic stress might evoke pathological mitochondrial phenotypes in cultured patient fibroblasts, providing a platform for the pre-clinical individualized evaluation of investigational therapeutics. Here, substitution of galactose for glucose in culture media was used to redirect CMT2A patient fibroblasts (MFN2 T105M, R274W, H361Y, R364W) from glycolytic metabolism to mitochondrial oxidative phosphorylation, which provoked characteristic mitochondrial fragmentation and depolarization and induced a distinct transcriptional signature. Pharmacological MFN activation of metabolically reprogrammed fibroblasts partially reversed the mitochondrial abnormalities in CMT2A and CMT1 and a subset of Parkinson’s and Alzheimer’s disease patients, implicating addressable mitochondrial dysdynamism in these illnesses.
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Affiliation(s)
- Xiawei Dang
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63110, USA; (X.D.); (E.K.W.)
| | - Emily K. Walton
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63110, USA; (X.D.); (E.K.W.)
| | - Barbara Zablocka
- Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland;
| | - Robert H. Baloh
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA;
| | - Michael E. Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA;
| | - Gerald W. Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, 660 S. Euclid Ave, St. Louis, MO 63110, USA; (X.D.); (E.K.W.)
- Correspondence: ; Tel.: +1-314-362-4892
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Schiavon CR, Shadel GS, Manor U. Impaired Mitochondrial Mobility in Charcot-Marie-Tooth Disease. Front Cell Dev Biol 2021; 9:624823. [PMID: 33598463 PMCID: PMC7882694 DOI: 10.3389/fcell.2021.624823] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 01/05/2021] [Indexed: 12/13/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is a progressive, peripheral neuropathy and the most commonly inherited neurological disorder. Clinical manifestations of CMT mutations are typically limited to peripheral neurons, the longest cells in the body. Currently, mutations in at least 80 different genes are associated with CMT and new mutations are regularly being discovered. A large portion of the proteins mutated in axonal CMT have documented roles in mitochondrial mobility, suggesting that organelle trafficking defects may be a common underlying disease mechanism. This review will focus on the potential role of altered mitochondrial mobility in the pathogenesis of axonal CMT, highlighting the conceptional challenges and potential experimental and therapeutic opportunities presented by this "impaired mobility" model of the disease.
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Affiliation(s)
- Cara R. Schiavon
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Gerald S. Shadel
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, United States
| | - Uri Manor
- Waitt Advanced Biophotonics Center, Salk Institute for Biological Studies, La Jolla, CA, United States
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Blocking the Bromodomains Function Contributes to Disturbances in Alga Chara vulgaris Spermatids Differentiation. Cells 2020; 9:cells9061352. [PMID: 32486024 PMCID: PMC7349737 DOI: 10.3390/cells9061352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/25/2020] [Accepted: 05/28/2020] [Indexed: 12/04/2022] Open
Abstract
Bromodomain containing (BRD) proteins play an essential role in many cellular processes. The aim of this study was to estimate activity of bromodomains during alga Chara vulgaris spermatids differentiation. The effect of a bromodomain inhibitor, JQ1 (100 μM), on the distribution of individual stages of spermatids and their ultrastructure was studied. The material was Feulgen stained and analysed in an electron microscope. JQ1 caused shortening of the early stages of spermiogenesis and a reverse reaction at the later stages. Additionally, in the same antheridium, spermatids at distant developmental stages were present. On the ultrastructural level, chromatin fibril system disorders and significantly distended endoplasmic reticulum (ER) cisternae already at the early stages were observed. Many autolytic vacuoles were also visible. The ultrastructural disturbances intensified after prolonged treatment with JQ1. The obtained data show that JQ1 treatment led to changes in the spermatid number and disturbances in chromatin condensation and to cytoplasm reduction. The current studies show some similarities between C. vulgaris and mammals spermiogenesis. Taken together, these results suggest that JQ1 interferes with the spermatid differentiation on many interdependent levels and seems to induce ER stress, which leads to spermatid degeneration. Studies on the role of bromodomains in algae spermiogenesis have not been conducted so far.
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9
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Zhang Y, Dong A, Xie K, Yu Y. Protective Effects of Hydrogen on Myocardial Mitochondrial Functions in Septic Mice. BIOMED RESEARCH INTERNATIONAL 2020; 2020:1568209. [PMID: 32083123 PMCID: PMC7011313 DOI: 10.1155/2020/1568209] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/13/2020] [Indexed: 11/17/2022]
Abstract
Enhancement of mitochondrial physiological function prevents sepsis-induced dysfunction. The present study aimed to elucidate the mechanism by which hydrogen (H2) affects mitochondrial function in a wild-type (WT) and homozygous nuclear factor erythroid 2-related factor 2 (Nrf2) knockout (KO, Nrf2-/-) murine model of sepsis. In myocardial tissues with severe sepsis, H2 gas treatment reduced mitochondrial dysfunction, whereas zinc protoporphyrin (ZnPPIX) negated these beneficial effects. H2 treatment upregulated the protein expression of mitofusin-2 (Mfn2), peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), and protein heme oxygenase-1 (HO-1) in WT mice with severe sepsis but not in their Nrf2-/- counterparts, and this upregulation was inhibited in the presence of ZnPPIX. In conclusion, the mechanism by which H2 limits organ damage in mice with severe sepsis involves HO-1, whereas the mechanism that limits severe sepsis-related mitochondrial dysfunction involves both HO-1 and Nrf2.
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Affiliation(s)
- Yuanyuan Zhang
- Department of Anesthesiology, General Hospital of Tianjin Medical University, Tianjin, China
| | - Aili Dong
- Department of Anesthesiology, General Hospital of Tianjin Medical University, Tianjin, China
| | - Keliang Xie
- Department of Anesthesiology, General Hospital of Tianjin Medical University, Tianjin, China
| | - Yonghao Yu
- Department of Anesthesiology, General Hospital of Tianjin Medical University, Tianjin, China
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De Vecchis D, Brandner A, Baaden M, Cohen MM, Taly A. A Molecular Perspective on Mitochondrial Membrane Fusion: From the Key Players to Oligomerization and Tethering of Mitofusin. J Membr Biol 2019; 252:293-306. [PMID: 31485701 DOI: 10.1007/s00232-019-00089-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 08/14/2019] [Indexed: 12/29/2022]
Abstract
Mitochondria are dynamic organelles characterized by an ultrastructural organization which is essential in maintaining their quality control and ensuring functional efficiency. The complex mitochondrial network is the result of the two ongoing forces of fusion and fission of inner and outer membranes. Understanding the functional details of mitochondrial dynamics is physiologically relevant as perturbations of this delicate equilibrium have critical consequences and involved in several neurological disorders. Molecular actors involved in this process are large GTPases from the dynamin-related protein family. They catalyze nucleotide-dependent membrane remodeling and are widely conserved from bacteria to higher eukaryotes. Although structural characterization of different family members has contributed in understanding molecular mechanisms of mitochondrial dynamics in more detail, the complete structure of some members as well as the precise assembly of functional oligomers remains largely unknown. As increasing structural data become available, the domain modularity across the dynamin superfamily emerged as a foundation for transfering the knowledge towards less characterized members. In this review, we will first provide an overview of the main actors involved in mitochondrial dynamics. We then discuss recent example of computational methodologies for the study of mitofusin oligomers, and present how the usage of integrative modeling in conjunction with biochemical data can be an asset in progressing the still challenging field of membrane dynamics.
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Affiliation(s)
- Dario De Vecchis
- School of Medicine, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, LIGHT Building, Leeds, LS2 9JT, UK.
| | - Astrid Brandner
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 Rue Pierre et Marie Curie, 75005, Paris, France.,Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Marc Baaden
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 Rue Pierre et Marie Curie, 75005, Paris, France.,Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France
| | - Mickael M Cohen
- Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France.,Laboratoire de Biologie Cellulaire et Moléculaire des Eucaryotes, Sorbonne Université, CNRS, UMR 8226, Paris, France
| | - Antoine Taly
- CNRS, Université de Paris, UPR 9080, Laboratoire de Biochimie Théorique, 13 Rue Pierre et Marie Curie, 75005, Paris, France. .,Institut de Biologie Physico-Chimique - Fondation Edmond de Rothschild, PSL Research University, Paris, France.
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Escobar-Henriques M, Joaquim M. Mitofusins: Disease Gatekeepers and Hubs in Mitochondrial Quality Control by E3 Ligases. Front Physiol 2019; 10:517. [PMID: 31156446 PMCID: PMC6533591 DOI: 10.3389/fphys.2019.00517] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/11/2019] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are dynamic organelles engaged in quality control and aging processes. They constantly undergo fusion, fission, transport, and anchoring events, which empower mitochondria with a very interactive behavior. The membrane remodeling processes needed for fusion require conserved proteins named mitofusins, MFN1 and MFN2 in mammals and Fzo1 in yeast. They are the first determinants deciding on whether communication and content exchange between different mitochondrial populations should occur. Importantly, each cell possesses hundreds of mitochondria, with a different severity of mitochondrial mutations or dysfunctional proteins, which potentially spread damage to the entire network. Therefore, the degree of their merging capacity critically influences cellular fitness. In turn, the mitochondrial network rapidly and dramatically changes in response to metabolic and environmental cues. Notably, cancer or obesity conditions, and stress experienced by neurons and cardiomyocytes, for example, triggers the downregulation of mitofusins and thus fragmentation of mitochondria. This places mitofusins upfront in sensing and transmitting stress. In fact, mitofusins are almost entirely exposed to the cytoplasm, a topology suitable for a critical relay point in information exchange between mitochondria and their cellular environment. Consistent with their topology, mitofusins are either activated or repressed by cytosolic post-translational modifiers, mainly by ubiquitin. Ubiquitin is a ubiquitous small protein orchestrating multiple quality control pathways, which is covalently attached to lysine residues in its substrates, or in ubiquitin itself. Importantly, from a chain of events also mediated by E1 and E2 enzymes, E3 ligases perform the ultimate and determinant step in substrate choice. Here, we review the ubiquitin E3 ligases that modify mitofusins. Two mitochondrial E3 enzymes—March5 and MUL1—one ligase located to the ER—Gp78—and finally three cytosolic enzymes—MGRN1, HUWE1, and Parkin—were shown to ubiquitylate mitofusins, in response to a variety of cellular inputs. The respective outcomes on mitochondrial morphology, on contact sites to the endoplasmic reticulum and on destructive processes, like mitophagy or apoptosis, are presented. Ultimately, understanding the mechanisms by which E3 ligases and mitofusins sense and bi-directionally signal mitochondria-cytosolic dysfunctions could pave the way for therapeutic approaches in neurodegenerative, cardiovascular, and obesity-linked diseases.
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Affiliation(s)
- Mafalda Escobar-Henriques
- Center for Molecular Medicine Cologne (CMMC), Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Mariana Joaquim
- Center for Molecular Medicine Cologne (CMMC), Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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Molecular modelling of mitofusin 2 for a prediction for Charcot-Marie-Tooth 2A clinical severity. Sci Rep 2018; 8:16900. [PMID: 30442897 PMCID: PMC6237821 DOI: 10.1038/s41598-018-35133-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/31/2018] [Indexed: 12/30/2022] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is an autosomal dominant neuropathy caused by mutations in the mitofusin 2 gene (MFN2). More than 100 MFN2 gene mutations have been reported so far, with majority located within the GTPase domain encoding region. These domain-specific mutations present wide range of symptoms with differences associated with distinct amino acid substitutions in the same position. Due to the lack of conclusive phenotype-genotype correlation the predictive value of genetic results remains still limited. We have explored whether changes in the protein structure caused by MFN2 mutations can help to explain diseases phenotypes. Using a stable protein model, we evaluated the effect of 26 substitutions on the MFN2 structure and predicted the molecular consequences of such alterations. The observed changes were correlated with clinical features associated with a given mutation. Of all tested mutations positive correlation of molecular modelling with the clinical features reached 73%. Our analysis revealed that molecular modelling of mitofusin 2 mutations is a powerful tool, which predicts associated pathogenic impacts and that these correlate with clinical outcomes. This approach may aid an early diagnosis and prediction of symptoms severity in CMT2A patients.
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Beyond Deubiquitylation: USP30-Mediated Regulation of Mitochondrial Homeostasis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1038:133-148. [DOI: 10.1007/978-981-10-6674-0_10] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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