1
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Franco A, Li J, Kelly DP, Hershberger RE, Marian AJ, Lewis RM, Song M, Dang X, Schmidt AD, Mathyer ME, Edwards JR, Strong CDG, Dorn GW. A human mitofusin 2 mutation can cause mitophagic cardiomyopathy. eLife 2023; 12:e84235. [PMID: 37910431 PMCID: PMC10619978 DOI: 10.7554/elife.84235] [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: 10/16/2022] [Accepted: 09/26/2023] [Indexed: 11/03/2023] Open
Abstract
Cardiac muscle has the highest mitochondrial density of any human tissue, but mitochondrial dysfunction is not a recognized cause of isolated cardiomyopathy. Here, we determined that the rare mitofusin (MFN) 2 R400Q mutation is 15-20× over-represented in clinical cardiomyopathy, whereas this specific mutation is not reported as a cause of MFN2 mutant-induced peripheral neuropathy, Charcot-Marie-Tooth disease type 2A (CMT2A). Accordingly, we interrogated the enzymatic, biophysical, and functional characteristics of MFN2 Q400 versus wild-type and CMT2A-causing MFN2 mutants. All MFN2 mutants had impaired mitochondrial fusion, the canonical MFN2 function. Compared to MFN2 T105M that lacked catalytic GTPase activity and exhibited normal activation-induced changes in conformation, MFN2 R400Q and M376A had normal GTPase activity with impaired conformational shifting. MFN2 R400Q did not suppress mitochondrial motility, provoke mitochondrial depolarization, or dominantly suppress mitochondrial respiration like MFN2 T105M. By contrast to MFN2 T105M and M376A, MFN2 R400Q was uniquely defective in recruiting Parkin to mitochondria. CRISPR editing of the R400Q mutation into the mouse Mfn2 gene induced perinatal cardiomyopathy with no other organ involvement; knock-in of Mfn2 T105M or M376V did not affect the heart. RNA sequencing and metabolomics of cardiomyopathic Mfn2 Q/Q400 hearts revealed signature abnormalities recapitulating experimental mitophagic cardiomyopathy. Indeed, cultured cardiomyoblasts and in vivo cardiomyocytes expressing MFN2 Q400 had mitophagy defects with increased sensitivity to doxorubicin. MFN2 R400Q is the first known natural mitophagy-defective MFN2 mutant. Its unique profile of dysfunction evokes mitophagic cardiomyopathy, suggesting a mechanism for enrichment in clinical cardiomyopathy.
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Affiliation(s)
- Antonietta Franco
- Department of Internal Medicine, Pharmacogenomics, Washington University School of MedicineSt LouisUnited States
| | - Jiajia Li
- Department of Internal Medicine, Pharmacogenomics, Washington University School of MedicineSt LouisUnited States
| | - Daniel P Kelly
- Department of Medicine, Cardiovascular Institute, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Ray E Hershberger
- Department of Internal Medicine, Divisions of Human Genetics and Cardiovascular Medicine, Ohio State UniversityColumbusUnited States
| | - Ali J Marian
- Center for Cardiovascular Genetic Research, University of Texas Health Science Center at HoustonHoustonUnited States
| | - Renate M Lewis
- Department of Neurology, Washington University School of MedicineSt. LouisUnited States
| | - Moshi Song
- Department of Internal Medicine, Pharmacogenomics, Washington University School of MedicineSt LouisUnited States
| | - Xiawei Dang
- Department of Internal Medicine, Pharmacogenomics, Washington University School of MedicineSt LouisUnited States
| | - Alina D Schmidt
- Department of Internal Medicine (Dermatology), Washington University School of MedicineSt. LouisUnited States
| | - Mary E Mathyer
- Department of Internal Medicine (Dermatology), Washington University School of MedicineSt. LouisUnited States
| | - John R Edwards
- Department of Internal Medicine, Pharmacogenomics, Washington University School of MedicineSt LouisUnited States
| | - Cristina de Guzman Strong
- Department of Internal Medicine (Dermatology), Washington University School of MedicineSt. LouisUnited States
| | - Gerald W Dorn
- Department of Internal Medicine, Pharmacogenomics, Washington University School of MedicineSt LouisUnited States
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2
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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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3
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Chen T, Wang Y, Wang YH, Hang CH. The Mfn1-βIIPKC Interaction Regulates Mitochondrial Dysfunction via Sirt3 Following Experimental Subarachnoid Hemorrhage. Transl Stroke Res 2022; 13:845-857. [PMID: 35192161 DOI: 10.1007/s12975-022-00999-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 01/21/2022] [Accepted: 02/16/2022] [Indexed: 10/19/2022]
Abstract
Neuronal injury following subarachnoid hemorrhage (SAH) has been shown to be associated with mitochondrial dysfunction and oxidative stress. βIIPKC, a subtype of protein kinase C (PKC), accumulates on the mitochondrial outer membrane and phosphorylates mitofusin 1 (Mfn1) at serine 86. Here, we investigated the role of Mfn1-βIIPKC interaction in brain damage and neurological function in both in vivo and in vitro experimental SAH models. The expression of βIIPKC protein and the interaction of Mfn1-βIIPKC were found to be increased after OxyHb treatment in primary cultured cortical neurons and were also observed in the brain following SAH in rats. Treatment with the βIIPKC inhibitor βIIV5-3 or SAMβA, a peptide that selectively antagonizes Mfn1-βIIPKC association, significantly attenuated the OxyHb-induced neuronal injury and apoptosis. These protective effects were accompanied by inhibited mitochondrial dysfunction and preserved mitochondrial biogenesis. The results of western blot showed that βIIV5-3 or SAMβA markedly increased the expression of Sirt3 and enhanced the activities of its downstream mitochondrial antioxidant enzymes in OxyHb-treated neurons. Knockdown of Sirt3 via specific targeted small interfering RNA (siRNA) partially prevented the βIIV5-3- or SAMβA-induced protection and antioxidative effects. In addition, treatment with βIIV5-3 or SAMβA in vivo was found to obviously reduce brain edema, alleviate neuroinflammation, and preserve neurological function after experimental SAH in rats. In congruent with in vitro data, the protection induced by βIIV5-3 or SAMβA was reduced by Sirt3 knockdown in vivo. In summary, our present results showed that blocking Mfn1-βIIPKC interaction protects against brain damage and mitochondrial dysfunction via Sirt3 following experimental SAH.
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Affiliation(s)
- Tao Chen
- Department of Neurosurgery, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, 210000, Jiangsu, China
- Department of Neurosurgery, The 904Th Hospital of PLA, Medical School of Anhui Medical University, Wuxi, 214044, Jiangsu, China
| | - Yue Wang
- Department of Neurosurgery, The 904Th Hospital of PLA, Medical School of Anhui Medical University, Wuxi, 214044, Jiangsu, China
| | - Yu-Hai Wang
- Department of Neurosurgery, The 904Th Hospital of PLA, Medical School of Anhui Medical University, Wuxi, 214044, Jiangsu, China.
| | - Chun-Hua Hang
- Department of Neurosurgery, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, 210000, Jiangsu, China.
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4
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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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5
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Baggio F, Hetzel U, Nufer L, Kipar A, Hepojoki J. A subpopulation of arenavirus nucleoprotein localizes to mitochondria. Sci Rep 2021; 11:21048. [PMID: 34702948 PMCID: PMC8548533 DOI: 10.1038/s41598-021-99887-5] [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: 04/27/2021] [Accepted: 09/30/2021] [Indexed: 12/02/2022] Open
Abstract
Viruses need cells for their replication and, therefore, ways to hijack cellular functions. Mitochondria play fundamental roles within the cell in metabolism, immunity and regulation of homeostasis due to which some viruses aim to alter mitochondrial functions. Herein we show that the nucleoprotein (NP) of arenaviruses enters the mitochondria of infected cells, affecting the mitochondrial morphology. Reptarenaviruses cause boid inclusion body disease (BIBD) that is characterized, especially in boas, by the formation of cytoplasmic inclusion bodies (IBs) comprising reptarenavirus NP within the infected cells. We initiated this study after observing electron-dense material reminiscent of IBs within the mitochondria of reptarenavirus infected boid cell cultures in an ultrastructural study. We employed immuno-electron microscopy to confirm that the mitochondrial inclusions indeed contain reptarenavirus NP. Mutations to a putative N-terminal mitochondrial targeting signal (MTS), identified via software predictions in both mamm- and reptarenavirus NPs, did not affect the mitochondrial localization of NP, suggesting that it occurs independently of MTS. In support of MTS-independent translocation, we did not detect cleavage of the putative MTSs of arenavirus NPs in reptilian or mammalian cells. Furthermore, in vitro translated NPs could not enter isolated mitochondria, suggesting that the translocation requires cellular factors or conditions. Our findings suggest that MTS-independent mitochondrial translocation of NP is a shared feature among arenaviruses. We speculate that by targeting the mitochondria arenaviruses aim to alter mitochondrial metabolism and homeostasis or affect the cellular defense.
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Affiliation(s)
- Francesca Baggio
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland. .,Center for Clinical Studies, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.
| | - Udo Hetzel
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.,Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, 00014, Helsinki, Finland
| | - Lisbeth Nufer
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland
| | - Anja Kipar
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.,Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, 00014, Helsinki, Finland
| | - Jussi Hepojoki
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, 8057, Zurich, Switzerland.,Department of Virology, Medicum, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
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6
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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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7
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Yamaguchi M, Lee IS, Jantrapirom S, Suda K, Yoshida H. Drosophila models to study causative genes for human rare intractable neurological diseases. Exp Cell Res 2021; 403:112584. [PMID: 33812867 DOI: 10.1016/j.yexcr.2021.112584] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/25/2021] [Accepted: 03/27/2021] [Indexed: 12/11/2022]
Abstract
Drosophila is emerging as a convenient model for investigating human diseases. Functional homologues of almost 75% of human disease-related genes are found in Drosophila. Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease that causes defects in motoneurons. Charcot-Marie-Tooth disease (CMT) is one of the most commonly found inherited neuropathies affecting both motor and sensory neurons. No effective therapy has been established for either of these diseases. In this review, after overviewing ALS, Drosophila models targeting several ALS-causing genes, including TDP-43, FUS and Ubiquilin2, are described with their genetic interactants. Then, after overviewing CMT, examples of Drosophila models targeting several CMT-causing genes, including mitochondria-related genes and FIG 4, are also described with their genetic interactants. In addition, we introduce Sotos syndrome caused by mutations in the epigenetic regulator gene NSD1. Lastly, several genes and pathways that commonly interact with ALS- and/or CMT-causing genes are described. In the case of ALS and CMT that have many causative genes, it may be not practical to perform gene therapy for each of the many disease-causing genes. The possible uses of the common genes and pathways as novel diagnosis markers and effective therapeutic targets are discussed.
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Affiliation(s)
- Masamitsu Yamaguchi
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan; Kansai Gakken Laboratory, Kankyo Eisei Yakuhin Co. Ltd., Seika-cho, Kyoto, 619-0237, Japan
| | - Im-Soon Lee
- Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea
| | - Salinee Jantrapirom
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Kojiro Suda
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Hideki Yoshida
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
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8
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Chung KW, Kim JS, Lee KS. A Database of Caenorhabditis elegans Locomotion and Body Posture Phenotypes for the Peripheral Neuropathy Model. Mol Cells 2020; 43:880-888. [PMID: 33115980 PMCID: PMC7604027 DOI: 10.14348/molcells.2020.0178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/17/2022] Open
Abstract
Inherited peripheral neuropathy is a heterogeneous group of peripheral neurodegenerative disorders including Charcot-Marie-Tooth disease. Many peripheral neuropathies often accompany impaired axonal construction and function. To study the molecular and cellular basis of axon-defective peripheral neuropathy, we explore the possibility of using Caenorhabditis elegans, a powerful nematode model equipped with a variety of genetics and imaging tools. In search of potential candidates of C. elegans peripheral neuropathy models, we monitored the movement and the body posture patterns of 26 C. elegans strains with disruption of genes associated with various peripheral neuropathies and compiled a database of their phenotypes. Our assay showed that movement features of the worms with mutations in HSPB1, MFN2, DYNC1H1, and KIF1B human homologues are significantly different from the control strain, suggesting they are viable candidates for C. elegans peripheral neuropathy models.
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Affiliation(s)
- Ki Wha Chung
- Department of Biological Sciences, Kongju National University, Gongju 32588, Korea
| | - Ju Seong Kim
- Department of Biological Sciences, Kongju National University, Gongju 32588, Korea
| | - Kyung Suk Lee
- Department of Physics Education, Kongju National University, Gongju 32588, Korea
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9
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Recent Advances in Drosophila Models of Charcot-Marie-Tooth Disease. Int J Mol Sci 2020; 21:ijms21197419. [PMID: 33049996 PMCID: PMC7582988 DOI: 10.3390/ijms21197419] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/06/2020] [Accepted: 10/06/2020] [Indexed: 12/15/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is one of the most common inherited peripheral neuropathies. CMT patients typically show slowly progressive muscle weakness and sensory loss in a distal dominant pattern in childhood. The diagnosis of CMT is based on clinical symptoms, electrophysiological examinations, and genetic testing. Advances in genetic testing technology have revealed the genetic heterogeneity of CMT; more than 100 genes containing the disease causative mutations have been identified. Because a single genetic alteration in CMT leads to progressive neurodegeneration, studies of CMT patients and their respective models revealed the genotype-phenotype relationships of targeted genes. Conventionally, rodents and cell lines have often been used to study the pathogenesis of CMT. Recently, Drosophila has also attracted attention as a CMT model. In this review, we outline the clinical characteristics of CMT, describe the advantages and disadvantages of using Drosophila in CMT studies, and introduce recent advances in CMT research that successfully applied the use of Drosophila, in areas such as molecules associated with mitochondria, endosomes/lysosomes, transfer RNA, axonal transport, and glucose metabolism.
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10
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Forte M, Schirone L, Ameri P, Basso C, Catalucci D, Modica J, Chimenti C, Crotti L, Frati G, Rubattu S, Schiattarella GG, Torella D, Perrino C, Indolfi C, Sciarretta S. The role of mitochondrial dynamics in cardiovascular diseases. Br J Pharmacol 2020; 178:2060-2076. [DOI: 10.1111/bph.15068] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 03/31/2020] [Accepted: 04/01/2020] [Indexed: 12/22/2022] Open
Affiliation(s)
- Maurizio Forte
- Department of AngioCardioNeurology IRCCS Neuromed Pozzili Italy
| | - Leonardo Schirone
- Department of Medical and Surgical Sciences and Biotechnologies Sapienza University of Rome Latina Italy
- Department of Internal, Anesthetic and Cardiovascular Clinical Sciences “La Sapienza” University of Rome Rome Italy
| | - Pietro Ameri
- Cardiovascular Disease Unit IRCCS Ospedale Policlinico Genova Italy
- Department of Internal Medicine University of Genova Genova Italy
| | - Cristina Basso
- Cardiovascular Pathology Unit, Department of Cardiac, Thoracic, Vascular Sciences and Public Health University of Padua Medical School Padova Italy
| | - Daniele Catalucci
- Humanitas Clinical and Research Center IRCCS Rozzano Italy
- National Research Council Institute of Genetic and Biomedical Research ‐ UOS Milan Italy
| | - Jessica Modica
- Humanitas Clinical and Research Center IRCCS Rozzano Italy
- National Research Council Institute of Genetic and Biomedical Research ‐ UOS Milan Italy
| | - Cristina Chimenti
- Department of Cardiovascular, Respiratory, Nephrologic, and Geriatric Sciences Sapienza University of Rome Rome Italy
| | - Lia Crotti
- Istituto Auxologico Italiano IRCCS, Center for Cardiac Arrhythmias of Genetic Origin and Laboratory of Cardiovascular Genetics Milan Italy
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular, Neural and Metabolic Sciences San Luca Hospital Milan Italy
- Department of Medicine and Surgery Università Milano‐Bicocca Milan Italy
| | - Giacomo Frati
- Department of AngioCardioNeurology IRCCS Neuromed Pozzili Italy
- Department of Medical and Surgical Sciences and Biotechnologies Sapienza University of Rome Latina Italy
| | - Speranza Rubattu
- Department of AngioCardioNeurology IRCCS Neuromed Pozzili Italy
- Department of Clinical and Molecular Medicine, School of Medicine and Psychology Sapienza University of Rome Rome Italy
| | - Gabriele Giacomo Schiattarella
- Department of Internal Medicine (Cardiology) University of Texas Southwestern Medical Center Dallas TX USA
- Division of Cardiology, Department of Advanced Biomedical Sciences Federico II University of Naples Naples Italy
| | - Daniele Torella
- Molecular and Cellular Cardiology Laboratory, Department of Experimental and Clinical Medicine Magna Graecia University Catanzaro Italy
| | - Cinzia Perrino
- Division of Cardiology, Department of Advanced Biomedical Sciences Federico II University of Naples Naples Italy
| | - Ciro Indolfi
- Molecular and Cellular Cardiology Laboratory, Department of Experimental and Clinical Medicine Magna Graecia University Catanzaro Italy
| | - Sebastiano Sciarretta
- Department of AngioCardioNeurology IRCCS Neuromed Pozzili Italy
- Department of Medical and Surgical Sciences and Biotechnologies Sapienza University of Rome Latina Italy
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11
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Ballard A, Zeng R, Zarei A, Shao C, Cox L, Yan H, Franco A, Dorn GW, Faccio R, Veis DJ. The tethering function of mitofusin2 controls osteoclast differentiation by modulating the Ca 2+-NFATc1 axis. J Biol Chem 2020; 295:6629-6640. [PMID: 32165499 DOI: 10.1074/jbc.ra119.012023] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/06/2020] [Indexed: 12/16/2022] Open
Abstract
Dynamic regulation of the mitochondrial network by mitofusins (MFNs) modulates energy production, cell survival, and many intracellular signaling events, including calcium handling. However, the relative importance of specific mitochondrial functions and their dependence on MFNs vary greatly among cell types. Osteoclasts have many mitochondria, and increased mitochondrial biogenesis and oxidative phosphorylation enhance bone resorption, but little is known about the mitochondrial network or MFNs in osteoclasts. Because expression of each MFN isoform increases with osteoclastogenesis, we conditionally deleted MFN1 and MFN2 (double conditional KO (dcKO)) in murine osteoclast precursors, finding that this increased bone mass in young female mice and abolished osteoclast precursor differentiation into mature osteoclasts in vitro Defective osteoclastogenesis was reversed by overexpression of MFN2 but not MFN1; therefore, we generated mice lacking only MFN2 in osteoclasts. MFN2-deficient female mice had increased bone mass at 1 year and resistance to Receptor Activator of NF-κB Ligand (RANKL)-induced osteolysis at 8 weeks. To explore whether MFN-mediated tethering or mitophagy is important for osteoclastogenesis, we overexpressed MFN2 variants defective in either function in dcKO precursors and found that, although mitophagy was dispensable for differentiation, tethering was required. Because the master osteoclastogenic transcriptional regulator nuclear factor of activated T cells 1 (NFATc1) is calcium-regulated, we assessed calcium release from the endoplasmic reticulum and store-operated calcium entry and found that the latter was blunted in dcKO cells. Restored osteoclast differentiation by expression of intact MFN2 or the mitophagy-defective variant was associated with normalization of store-operated calcium entry and NFATc1 levels, indicating that MFN2 controls mitochondrion-endoplasmic reticulum tethering in osteoclasts.
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Affiliation(s)
- Anna Ballard
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Rong Zeng
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Allahdad Zarei
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Christine Shao
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Linda Cox
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110.,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Hui Yan
- Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110.,Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.,Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Antonietta Franco
- Center for Pharmacogenomics, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Gerald W Dorn
- Center for Pharmacogenomics, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Roberta Faccio
- Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110.,Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110.,Shriners Hospitals for Children, St. Louis, Missouri 63110
| | - Deborah J Veis
- Division of Bone and Mineral Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 .,Musculoskeletal Research Center, Washington University School of Medicine, St. Louis, Missouri 63110.,Shriners Hospitals for Children, St. Louis, Missouri 63110.,Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
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12
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Suda K, Muraoka Y, Ortega-Yáñez A, Yoshida H, Kizu F, Hochin T, Kimura H, Yamaguchi M. Reduction of Rpd3 suppresses defects in locomotive ability and neuronal morphology induced by the knockdown of Drosophila SLC25A46 via an epigenetic pathway. Exp Cell Res 2019; 385:111673. [PMID: 31614134 DOI: 10.1016/j.yexcr.2019.111673] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 10/07/2019] [Accepted: 10/09/2019] [Indexed: 02/06/2023]
Abstract
Mitochondrial dysfunction causes various diseases. Mutations in the SLC25A46 gene have been identified in mitochondrial diseases that are sometimes classified as Charcot-Marie-Tooth disease type 2, optic atrophy, and Leigh syndrome. A homolog of SLC25A46 was identified in Drosophila and designated as dSLC25A46 (CG5755). We previously established mitochondrial disease model targeting of dSLC25A46, which causes locomotive dysfunction and morphological defects at neuromuscular junctions, such as reduced synaptic branch lengths and decreased numbers of boutons. The diverse symptoms of mitochondrial diseases carrying mutations in SLC25A46 may be associated with the dysregulation of some epigenetic regulators. To investigate the involvement of epigenetic regulators in mitochondrial diseases, we examined candidate epigenetic regulators that interact with human SLC25A46 by searching Gene Expression Omnibus (GEO). We discovered that HDAC1 binds to several SLC25A46 genomic regions in human cultured CD4 (+) cells, and attempted to prove this in an in vivo Drosophila model. By demonstrating that Rpd3, Drosophila HDAC1, regulates the histone H4K8 acetylation state in dSLC25A46 genomic regions, we confirmed that Rpd3 is a novel epigenetic regulator modifying the phenotypes observed with the mitochondrial disease model targeting of dSLC25A46. The functional reduction of Rpd3 rescued the deficient locomotive ability and aberrant morphology of motoneurons at presynaptic terminals induced by the dSLC25A46 knockdown. The present results suggest that the inhibition of HDAC1 suppresses the pathogenic processes that lead to the degeneration of motoneurons in mitochondrial diseases.
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Affiliation(s)
- Kojiro Suda
- Department of Applied Biology, Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Yuuka Muraoka
- Department of Applied Biology, Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Andrea Ortega-Yáñez
- Departamento de Genética del Desarrollo Y Fisiología Molecular Instituto de Biotecnología, Universidad Nacional Autónoma de México, Mexico
| | - Hideki Yoshida
- Department of Applied Biology, Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
| | - Fuma Kizu
- Department of Information Science, Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Teruhisa Hochin
- Department of Information Science, Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Hiroshi Kimura
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan
| | - Masamitsu Yamaguchi
- Department of Applied Biology, Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
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13
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Yamaguchi M, Takashima H. Drosophila Charcot-Marie-Tooth Disease Models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1076:97-117. [PMID: 29951817 DOI: 10.1007/978-981-13-0529-0_7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) was initially described in 1886. It is characterized by defects in the peripheral nervous system, including sensory and motor neurons. Although more than 80 CMT-causing genes have been identified to date, an effective therapy has not yet been developed for this disease. Since Drosophila does not have axons surrounded by myelin sheaths or Schwann cells, the establishment of a demyelinating CMT model is not appropriate. In this chapter, after overviewing CMT, examples of Drosophila CMT models with axonal neuropathy and other animal CMT models are described.
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Affiliation(s)
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
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14
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Nivison MP, Ericson NG, Green VM, Bielas JH, Campbell JS, Horner PJ. Age-related accumulation of phosphorylated mitofusin 2 protein in retinal ganglion cells correlates with glaucoma progression. Exp Neurol 2017; 296:49-61. [PMID: 28684211 PMCID: PMC6021128 DOI: 10.1016/j.expneurol.2017.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 06/26/2017] [Accepted: 07/02/2017] [Indexed: 01/19/2023]
Abstract
Dysregulation of axonal bioenergetics is likely a key mechanism in the initiation and progression of age-related neurodegenerative diseases. Glaucoma is a quintessential neurodegenerative disorder characterized by progressive deterioration of the optic nerve (ON) and eventual death of retinal ganglion cells (RGCs). Age and elevation of intraocular pressure are key risk factors in glaucoma, but the common early hallmarks of decreased axonal transport and increased bioenergetic vulnerability likely underlie disease initiation. We examined the correlation between bioenergetics and axonal transport with mitochondrial mutation frequency and post-translational modifications of mitofusin 2 (Mfn2) in RGCs during glaucoma progression. No increase in the frequency of mtDNA mutations was detected, but we observed significant shifts in mitochondrial protein species. Mfn2 is a fusion protein that functions in mitochondrial biogenesis, maintenance, and mitochondrial transport. We demonstrate that Mfn2 accumulates selectively in RGCs during glaucomatous degeneration, that two novel states of Mfn2 exist in retina and ON, and identify a phosphorylated form that selectively accumulates in RGCs, but is absent in ON. Phosphorylation of Mfn2 is correlated with higher ubiquitination, and failure of the protein to reach the ON. Together, these data suggest that post-translational modification of Mfn2 is associated with its dysregulation during a window of metabolic vulnerability that precedes glaucomatous degeneration. Future work to either manipulate expression of Mfn2 or to prevent its degradation could have therapeutic value in the treatment of neurodegenerative diseases where long-tract axons are vulnerable.
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Affiliation(s)
- Mary P Nivison
- Department of Pathology, University of Washington, Seattle, WA, USA
| | - Nolan G Ericson
- Translational Research Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Virginia M Green
- Matrix Biology Program, Benaroya Research Institute, Seattle, WA, USA
| | - Jason H Bielas
- Department of Pathology, University of Washington, Seattle, WA, USA; Translational Research Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA; Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Jean S Campbell
- Department of Pathology, University of Washington, Seattle, WA, USA
| | - Philip J Horner
- Department of Neurological Surgery, University of Washington, Seattle, WA, USA.
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15
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Gong G, Song M, Csordas G, Kelly DP, Matkovich SJ, Dorn GW. Parkin-mediated mitophagy directs perinatal cardiac metabolic maturation in mice. Science 2015; 350:aad2459. [PMID: 26785495 DOI: 10.1126/science.aad2459] [Citation(s) in RCA: 331] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/16/2015] [Indexed: 12/11/2022]
Abstract
In developing hearts, changes in the cardiac metabolic milieu during the perinatal period redirect mitochondrial substrate preference from carbohydrates to fatty acids. Mechanisms responsible for this mitochondrial plasticity are unknown. Here, we found that PINK1-Mfn2-Parkin-mediated mitophagy directs this metabolic transformation in mouse hearts. A mitofusin (Mfn) 2 mutant lacking PINK1 phosphorylation sites necessary for Parkin binding (Mfn2 AA) inhibited mitochondrial Parkin translocation, suppressing mitophagy without impairing mitochondrial fusion. Cardiac Parkin deletion or expression of Mfn2 AA from birth, but not after weaning, prevented postnatal mitochondrial maturation essential to survival. Five-week-old Mfn2 AA hearts retained a fetal mitochondrial transcriptional signature without normal increases in fatty acid metabolism and mitochondrial biogenesis genes. Myocardial fatty acylcarnitine levels and cardiomyocyte respiration induced by palmitoylcarnitine were concordantly depressed. Thus, instead of transcriptional reprogramming, fetal cardiomyocyte mitochondria undergo perinatal Parkin-mediated mitophagy and replacement by mature adult mitochondria. Mitophagic mitochondrial removal underlies developmental cardiomyocyte mitochondrial plasticity and metabolic transitioning of perinatal hearts.
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Affiliation(s)
- Guohua Gong
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Moshi Song
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Gyorgy Csordas
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Daniel P Kelly
- Center for Metabolic Origins of Disease, Cardiovascular Metabolism Program, Sanford Burnham Prebys Medical Discovery Institute, Orlando, FL, USA
| | - Scot J Matkovich
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
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Abstract
SIGNIFICANCE Cardiac function is energetically demanding, reliant on efficient well-coupled mitochondria to generate adenosine triphosphate and fulfill the cardiac demand. Predictably then, mitochondrial dysfunction is associated with cardiac pathologies, often related to metabolic disease, most commonly diabetes. Diabetic cardiomyopathy (DCM), characterized by decreased left ventricular function, arises independently of coronary artery disease and atherosclerosis. Dysregulation of Ca(2+) handling, metabolic changes, and oxidative stress are observed in DCM, abnormalities reflected in alterations in mitochondrial energetics. Cardiac tissue from DCM patients also presents with altered mitochondrial morphology, suggesting a possible role of mitochondrial dynamics in its pathological progression. RECENT ADVANCES Abnormal mitochondrial morphology is associated with pathologies across diverse tissues, suggesting that this highly regulated process is essential for proper cell maintenance and physiological homeostasis. Highly structured cardiac myofibers were hypothesized to limit alterations in mitochondrial morphology; however, recent work has identified morphological changes in cardiac tissue, specifically in DCM. CRITICAL ISSUES Mitochondrial dysfunction has been reported independently from observations of altered mitochondrial morphology in DCM. The temporal relationship and causative nature between functional and morphological changes of mitochondria in the establishment/progression of DCM is unclear. FUTURE DIRECTIONS Altered mitochondrial energetics and morphology are not only causal for but also consequential to reactive oxygen species production, hence exacerbating oxidative damage through reciprocal amplification, which is integral to the progression of DCM. Therefore, targeting mitochondria for DCM will require better mechanistic characterization of morphological distortion and bioenergetic dysfunction.
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Affiliation(s)
- Chad A Galloway
- 1Department of Anesthesiology, University of Rochester School of Medicine and Dentistry, Rochester, New York
| | - Yisang Yoon
- 2Department of Physiology, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
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17
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Biala AK, Dhingra R, Kirshenbaum LA. Mitochondrial dynamics: Orchestrating the journey to advanced age. J Mol Cell Cardiol 2015; 83:37-43. [PMID: 25918048 DOI: 10.1016/j.yjmcc.2015.04.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/30/2015] [Accepted: 04/19/2015] [Indexed: 12/20/2022]
Abstract
Aging is a degenerative process that unfortunately is an inevitable part of life and risk factor for cardiovascular disease including heart failure. Among the several theories purported to explain the effects of age on cardiac dysfunction, the mitochondrion has emerged a central regulator of this process. Hence, it is not surprising that abnormalities in mitochondrial quality control including biogenesis and turnover have such detrimental effects on cardiac function. In fact mitochondria serve as a conduit for biological signals for apoptosis, necrosis and autophagy respectively. The removal of damaged mitochondria by autophagy/mitophagy is essential for mitochondrial quality control and cardiac homeostasis. Defects in mitochondrial dynamism fission/fusion events have been linked to cardiac senescence and heart failure. In this review we discuss the impact of aging on mitochondrial dynamics and senescence on cardiovascular health. This article is part of a Special Issue entitled: CV Aging.
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Affiliation(s)
- Agnieszka K Biala
- The Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Winnipeg, Manitoba R2H 2A6, Canada; Department of Physiology, Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada; Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada
| | - Rimpy Dhingra
- The Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Winnipeg, Manitoba R2H 2A6, Canada; Department of Physiology, Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada; Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada
| | - Lorrie A Kirshenbaum
- The Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Winnipeg, Manitoba R2H 2A6, Canada; Department of Physiology, Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada; Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada.
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18
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Bhandari P, Song M, Dorn GW. Dissociation of mitochondrial from sarcoplasmic reticular stress in Drosophila cardiomyopathy induced by molecularly distinct mitochondrial fusion defects. J Mol Cell Cardiol 2014; 80:71-80. [PMID: 25555803 DOI: 10.1016/j.yjmcc.2014.12.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 12/17/2014] [Accepted: 12/21/2014] [Indexed: 01/17/2023]
Abstract
Mitochondrial dynamism (fusion and fission) is responsible for remodeling interconnected mitochondrial networks in some cell types. Adult cardiac myocytes lack mitochondrial networks, and their mitochondria are inherently "fragmented". Mitochondrial fusion/fission is so infrequent in cardiomyocytes as to not be observable under normal conditions, suggesting that mitochondrial dynamism may be dispensable in this cell type. However, we previously observed that cardiomyocyte-specific genetic suppression of mitochondrial fusion factors optic atrophy 1 (Opa1) and mitofusin/MARF evokes cardiomyopathy in Drosophila hearts. We posited that fusion-mediated remodeling of mitochondria may be critical for cardiac homeostasis, although never directly observed. Alternately, we considered that inner membrane Opa1 and outer membrane mitofusin/MARF might have other as-yet poorly described roles that affect mitochondrial and cardiac function. Here we compared heart tube function in three models of mitochondrial fragmentation in Drosophila cardiomyocytes: Drp1 expression, Opa1 RNAi, and mitofusin MARF RNA1. Mitochondrial fragmentation evoked by enhanced Drp1-mediated fission did not adversely impact heart tube function. In contrast, RNAi-mediated suppression of either Opa1 or mitofusin/MARF induced cardiac dysfunction associated with mitochondrial depolarization and ROS production. Inhibiting ROS by overexpressing superoxide dismutase (SOD) or suppressing ROMO1 prevented mitochondrial and heart tube dysfunction provoked by Opa1 RNAi, but not by mitofusin/MARF RNAi. In contrast, enhancing the ability of endoplasmic/sarcoplasmic reticulum to handle stress by expressing Xbp1 rescued the cardiomyopathy of mitofusin/MARF insufficiency without improving that caused by Opa1 deficiency. We conclude that decreased mitochondrial size is not inherently detrimental to cardiomyocytes. Rather, preservation of mitochondrial function by Opa1 located on the inner mitochondrial membrane, and prevention of ER stress by mitofusin/MARF located on the outer mitochondrial membrane, are central functions of these "mitochondrial fusion proteins".
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Affiliation(s)
- Poonam Bhandari
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Moshi Song
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Gerald W Dorn
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
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20
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Chen Y, Sparks M, Bhandari P, Matkovich SJ, Dorn GW. Mitochondrial genome linearization is a causative factor for cardiomyopathy in mice and Drosophila. Antioxid Redox Signal 2014; 21:1949-59. [PMID: 23909626 PMCID: PMC4208594 DOI: 10.1089/ars.2013.5432] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
AIMS Mitofusin (Mfn)2 redundantly promotes mitochondrial outer membrane tethering and organelle fusion with Mfn1, and uniquely functions as the mitochondrial receptor for Parkin during PTEN-induced putative kinase 1 (PINK1)-Parkin-mediated mitophagy. Selective deletion of Mfn2 with retention of Mfn1 preserves mitochondrial fusion while rendering damaged mitochondria resistant to normal quality control culling mechanisms. Consequently, neuron and cardiomyocyte-specific Mfn2 gene ablation is associated with accumulation of damaged mitochondria and organ dysfunction. Here, we determined how mitochondrial DNA (mtDNA) damage contributes to cardiomyopathy in Mfn2-deficient hearts. RESULTS RNA sequencing of Mfn2-deficient hearts revealed increased expression of some nuclear-encoded mitochondrial genes, but mitochondrial-encoded transcripts were not upregulated in parallel and mtDNA content was decreased. Ultra-deep sequencing of mtDNA showed no increase in single nucleotide mutations, but copy number variations representing insertion-deletion (in-del) mutations were induced over time by cardiomyocyte-specific Mfn2 deficiency. Double-strand mtDNA breaks in the form of in-dels were confirmed by polymerase chain reaction, and in the form of linear mitochondrial genomes were identified by southern blot analysis. Linearization of Drosophila cardiomyocyte mtDNA using conditional cardiomyocyte-specific expression of mitochondrial targeted XhoI recapitulated the cardiomyopathy of Mfn2-deficient mouse hearts. INNOVATION This is the first description of mitochondrial genome linearization as a causative factor in cardiomyopathy. CONCLUSION One of the consequences of interrupting mitochondrial culling by the PINK1-Mfn2-Parkin mechanism is an increase in mtDNA double-stranded breaks, which adversely impact mitochondrial function and DNA replication.
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Affiliation(s)
- Yun Chen
- Department of Internal Medicine, Center for Pharmacogenomics, Washington University School of Medicine , St. Louis, Missouri
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21
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Bhandari P, Song M, Chen Y, Burelle Y, Dorn GW. Mitochondrial contagion induced by Parkin deficiency in Drosophila hearts and its containment by suppressing mitofusin. Circ Res 2013; 114:257-65. [PMID: 24192653 DOI: 10.1161/circresaha.114.302734] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
RATIONALE Dysfunctional Parkin-mediated mitophagic culling of senescent or damaged mitochondria is a major pathological process underlying Parkinson disease and a potential genetic mechanism of cardiomyopathy. Despite epidemiological associations between Parkinson disease and heart failure, the role of Parkin and mitophagic quality control in maintaining normal cardiac homeostasis is poorly understood. OBJECTIVE We used germline mutants and cardiac-specific RNA interference to interrogate Parkin regulation of cardiomyocyte mitochondria and examine functional crosstalk between mitophagy and mitochondrial dynamics in Drosophila heart tubes. METHODS AND RESULTS Transcriptional profiling of Parkin knockout mouse hearts revealed compensatory upregulation of multiple related E3 ubiquitin ligases. Because Drosophila lack most of these redundant genes, we examined heart tubes of parkin knockout flies and observed accumulation of enlarged hollow donut mitochondria with dilated cardiomyopathy, which could be rescued by cardiomyocyte-specific Parkin expression. Identical abnormalities were induced by cardiomyocyte-specific Parkin suppression using 2 different inhibitory RNAs. Parkin-deficient cardiomyocyte mitochondria exhibited dysmorphology, depolarization, and reactive oxygen species generation without calcium cycling abnormalities, pointing to a primary mitochondrial defect. Suppressing cardiomyocyte mitochondrial fusion in Parkin-deficient fly heart tubes completely prevented the cardiomyopathy and corrected mitochondrial dysfunction without normalizing mitochondrial dysmorphology, demonstrating a central role for mitochondrial fusion in the cardiomyopathy provoked by impaired mitophagy. CONCLUSIONS Parkin deficiency and resulting mitophagic disruption produces cardiomyopathy in part by contamination of the cardiomyocyte mitochondrial pool through fusion between improperly retained dysfunctional/senescent and normal mitochondria. Limiting mitochondrial contagion by inhibiting organelle fusion shows promise for minimizing organ dysfunction produced by defective mitophagic signaling.
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Affiliation(s)
- Poonam Bhandari
- From the Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO (P.B., M.S., Y.C., G.W.D.); and Department of Biomedical Sciences, University of Montreal, Quebec, Canada (Y.B.)
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22
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Eisner V, Csordás G, Hajnóczky G. Interactions between sarco-endoplasmic reticulum and mitochondria in cardiac and skeletal muscle - pivotal roles in Ca²⁺ and reactive oxygen species signaling. J Cell Sci 2013; 126:2965-78. [PMID: 23843617 DOI: 10.1242/jcs.093609] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mitochondria are strategically and dynamically positioned in the cell to spatially coordinate ATP production with energy needs and to allow the local exchange of material with other organelles. Interactions of mitochondria with the sarco-endoplasmic reticulum (SR/ER) have been receiving much attention owing to emerging evidence on the role these sites have in cell signaling, dynamics and biosynthetic pathways. One of the most important physiological and pathophysiological paradigms for SR/ER-mitochondria interactions is in cardiac and skeletal muscle. The contractile activity of these tissues has to be matched by mitochondrial ATP generation that is achieved, at least in part, by propagation of Ca(2+) signals from SR to mitochondria. However, the muscle has a highly ordered structure, providing only limited opportunity for mitochondrial dynamics and interorganellar interactions. This Commentary focuses on the latest advances in the structure, function and disease relevance of the communication between SR/ER and mitochondria in muscle. In particular, we discuss the recent demonstration of SR/ER-mitochondria tethers that are formed by multiple proteins, and local Ca(2+) transfer between SR/ER and mitochondria.
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Affiliation(s)
- Verónica Eisner
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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23
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Chen Y, Lv L, Jiang Z, Yang H, Li S, Jiang Y. Mitofusin 2 protects hepatocyte mitochondrial function from damage induced by GCDCA. PLoS One 2013; 8:e65455. [PMID: 23755235 PMCID: PMC3675030 DOI: 10.1371/journal.pone.0065455] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 04/24/2013] [Indexed: 01/15/2023] Open
Abstract
Mitochondrial impairment is hypothesized to contribute to the pathogenesis of chronic cholestatic liver diseases. Mitofusin 2 (Mfn2) regulates mitochondrial morphology and signaling and is involved in the development of numerous mitochondrial-related diseases; however, a functional role for Mfn2 in chronic liver cholestasis which is characterized by increased levels of toxic bile acids remain unknown. Therefore, the aims of this study were to evaluate the expression levels of Mfn2 in liver samples from patients with extrahepatic cholestasis and to investigate the role Mfn2 during bile acid induced injury in vitro. Endogenous Mfn2 expression decreased in patients with extrahepatic cholestasis. Glycochenodeoxycholic acid (GCDCA) is the main toxic component of bile acid in patients with extrahepatic cholestasis. In human normal hepatocyte cells (L02), Mfn2 plays an important role in GCDCA-induced mitochondrial damage and changes in mitochondrial morphology. In line with the mitochondrial dysfunction, the expression of Mfn2 decreased significantly under GCDCA treatment conditions. Moreover, the overexpression of Mfn2 effectively attenuated mitochondrial fragmentation and reversed the mitochondrial damage observed in GCDCA-treated L02 cells. Notably, a truncated Mfn2 mutant that lacked the normal C-terminal domain lost the capacity to induce mitochondrial fusion. Increasing the expression of truncated Mfn2 also had a protective effect against the hepatotoxicity of GCDCA. Taken together, these findings indicate that the loss of Mfn2 may play a crucial role the pathogenesis of the liver damage that is observed in patients with extrahepatic cholestasis. The findings also indicate that Mfn2 may directly regulate mitochondrial metabolism independently of its primary fusion function. Therapeutic approaches that target Mfn2 may have protective effects against hepatotoxic of bile acids during cholestasis.
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Affiliation(s)
- Yongbiao Chen
- Department of Hepatobiliary Surgery, Fuzhou General Hospital, Fuzhou, China
- * E-mail: (YC); (YJ)
| | - Lizhi Lv
- Department of Hepatobiliary Surgery, Fuzhou General Hospital, Fuzhou, China
| | - Zhelong Jiang
- Department of Hepatobiliary Surgery, Fuzhou General Hospital, Fuzhou, China
| | - Hejun Yang
- Department of Hepatobiliary Surgery, Fuzhou General Hospital, Fuzhou, China
| | - Song Li
- Department of Hepatobiliary Surgery, Fuzhou General Hospital, Fuzhou, China
| | - Yi Jiang
- Department of Hepatobiliary Surgery, Fuzhou General Hospital, Fuzhou, China
- * E-mail: (YC); (YJ)
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Chen Y, Dorn GW. PINK1-phosphorylated mitofusin 2 is a Parkin receptor for culling damaged mitochondria. Science 2013; 340:471-5. [PMID: 23620051 DOI: 10.1126/science.1231031] [Citation(s) in RCA: 957] [Impact Index Per Article: 87.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Senescent and damaged mitochondria undergo selective mitophagic elimination through mechanisms requiring two Parkinson's disease factors, the mitochondrial kinase PINK1 (PTEN-induced putative kinase protein 1; PTEN is phosphatase and tensin homolog) and the cytosolic ubiquitin ligase Parkin. The nature of the PINK-Parkin interaction and the identity of key factors directing Parkin to damaged mitochondria are unknown. We show that the mitochondrial outer membrane guanosine triphosphatase mitofusin (Mfn) 2 mediates Parkin recruitment to damaged mitochondria. Parkin bound to Mfn2 in a PINK1-dependent manner; PINK1 phosphorylated Mfn2 and promoted its Parkin-mediated ubiqitination. Ablation of Mfn2 in mouse cardiac myocytes prevented depolarization-induced translocation of Parkin to the mitochondria and suppressed mitophagy. Accumulation of morphologically and functionally abnormal mitochondria induced respiratory dysfunction in Mfn2-deficient mouse embryonic fibroblasts and cardiomyocytes and in Parkin-deficient Drosophila heart tubes, causing dilated cardiomyopathy. Thus, Mfn2 functions as a mitochondrial receptor for Parkin and is required for quality control of cardiac mitochondria.
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Affiliation(s)
- Yun Chen
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
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