1
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Li CX, Talukder M, Xu YR, Zhu SY, Wang YX, Li JL. Cadmium causes cerebral mitochondrial dysfunction through regulating mitochondrial HSF1. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 360:124677. [PMID: 39127336 DOI: 10.1016/j.envpol.2024.124677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 07/15/2024] [Accepted: 08/03/2024] [Indexed: 08/12/2024]
Abstract
Mitochondria, as the powerhouse of the cell, play a vital role in maintaining cellular energy homeostasis and are known to be a primary target of cadmium (Cd) toxicity. The improper targeting of proteins to mitochondria can compromise the normal functions of the mitochondria. However, the precise mechanism by which protein localization contributes to the development of mitochondrial dysfunction induced by Cd is still not fully understood. For this research, Hy-Line white variety chicks (1-day-old) were used and equally distributed into 4 groups: the Control group (fed with a basic diet), the Cd35 group (basic diet with 35 mg/kg CdCl2), the Cd70 group (basic diet with 70 mg/kg CdCl2) and the Cd140 group (basic diet with 140 mg/kg CdCl2), respectively for 90 days. It was found that Cd caused the accumulation of heat shock factor 1 (HSF1) in the mitochondria, and the overexpression of HSF1 in the mitochondria led to mitochondrial dysfunction and neuronal damage. This process is due to the mitochondrial HSF1 (mtHSF1), causing mitochondrial fission through the upregulation of dynamin-related protein 1 (Drp1) content, while inhibiting oligomer formation of single-stranded DNA-binding protein 1 (SSBP1), resulting in the mitochondrial DNA (mtDNA) deletion. The findings unveil an unforeseen role of HSF1 in triggering mitochondrial dysfunction.
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Affiliation(s)
- Chen-Xi Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, PR China
| | - Milton Talukder
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, PR China; Department of Physiology and Pharmacology, Faculty of Animal Science and Veterinary Medicine, Patuakhali Science and Technology University, Barishal, 8210, Bangladesh
| | - Ya-Ru Xu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, PR China
| | - Shi-Yong Zhu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, PR China
| | - Yu-Xiang Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, PR China
| | - Jin-Long Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, 150030, PR China; Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, Northeast Agricultural University, Harbin, 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Northeast Agricultural University, Harbin, 150030, PR China.
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2
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Riccio AA, Bouvette J, Pedersen LC, Somai S, Dutcher RC, Borgnia MJ, Copeland WC. Structures of the mitochondrial single-stranded DNA binding protein with DNA and DNA polymerase γ. Nucleic Acids Res 2024:gkae670. [PMID: 39106165 DOI: 10.1093/nar/gkae670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 07/11/2024] [Accepted: 07/22/2024] [Indexed: 08/09/2024] Open
Abstract
The mitochondrial single-stranded DNA (ssDNA) binding protein, mtSSB or SSBP1, binds to ssDNA to prevent secondary structures of DNA that could impede downstream replication or repair processes. Clinical mutations in the SSBP1 gene have been linked to a range of mitochondrial disorders affecting nearly all organs and systems. Yet, the molecular determinants governing the interaction between mtSSB and ssDNA have remained elusive. Similarly, the structural interaction between mtSSB and other replisome components, such as the mitochondrial DNA polymerase, Polγ, has been minimally explored. Here, we determined a 1.9-Å X-ray crystallography structure of the human mtSSB bound to ssDNA. This structure uncovered two distinct DNA binding sites, a low-affinity site and a high-affinity site, confirmed through site-directed mutagenesis. The high-affinity binding site encompasses a clinically relevant residue, R38, and a highly conserved DNA base stacking residue, W84. Employing cryo-electron microscopy, we confirmed the tetrameric assembly in solution and capture its interaction with Polγ. Finally, we derived a model depicting modes of ssDNA wrapping around mtSSB and a region within Polγ that mtSSB binds.
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Affiliation(s)
- Amanda A Riccio
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Jonathan Bouvette
- Molecular Microscopy Consortium, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Lars C Pedersen
- Structure Function Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Shruti Somai
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Robert C Dutcher
- Macromolecular Structure Group, Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Mario J Borgnia
- Molecular Microscopy Consortium, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - William C Copeland
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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3
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Liu Y, Liu H, Zhang F, Xu H. The initiation of mitochondrial DNA replication. Biochem Soc Trans 2024; 52:1243-1251. [PMID: 38884788 PMCID: PMC11346463 DOI: 10.1042/bst20230952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/31/2024] [Accepted: 06/04/2024] [Indexed: 06/18/2024]
Abstract
Mitochondrial DNA replication is initiated by the transcription of mitochondrial RNA polymerase (mtRNAP), as mitochondria lack a dedicated primase. However, the mechanism determining the switch between continuous transcription and premature termination to generate RNA primers for mitochondrial DNA (mtDNA) replication remains unclear. The pentatricopeptide repeat domain of mtRNAP exhibits exoribonuclease activity, which is required for the initiation of mtDNA replication in Drosophila. In this review, we explain how this exonuclease activity contributes to primer synthesis in strand-coupled mtDNA replication, and discuss how its regulation might co-ordinate mtDNA replication and transcription in both Drosophila and mammals.
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Affiliation(s)
- Yi Liu
- Hubei Jiangxia Laboratory, Wuhan 430200, China
| | - Haibin Liu
- Hubei Jiangxia Laboratory, Wuhan 430200, China
| | - Fan Zhang
- National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, U.S.A
| | - Hong Xu
- National Heart, Lung and Blood Institute, NIH, Bethesda, MD 20892, U.S.A
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4
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Martucci M, Moretton A, Tarrés-Solé A, Ropars V, Lambert L, Vernet P, Solà M, Falkenberg M, Farge G, van den Wildenberg S. The mutation R107Q alters mtSSB ssDNA compaction ability and binding dynamics. Nucleic Acids Res 2024; 52:5912-5927. [PMID: 38742632 PMCID: PMC11162770 DOI: 10.1093/nar/gkae354] [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: 12/02/2023] [Revised: 04/02/2024] [Accepted: 04/22/2024] [Indexed: 05/16/2024] Open
Abstract
Mitochondrial single-stranded DNA-binding protein (mtSSB) is essential for mitochondrial DNA (mtDNA) replication. Recently, several mtSSB variants have been associated with autosomal dominant mitochondrial optic atrophy and retinal dystrophy. Here, we have studied at the molecular level the functional consequences of one of the most severe mtSSB variants, R107Q. We first studied the oligomeric state of this variant and observed that the mtSSBR107Q mutant forms stable tetramers in vitro. On the other hand, we showed, using complementary single-molecule approaches, that mtSSBR107Q displays a lower intramolecular ssDNA compaction ability and a higher ssDNA dissociation rate than the WT protein. Real-time competition experiments for ssDNA-binding showed a marked advantage of mtSSBWT over mtSSBR107Q. Combined, these results show that the R107Q mutation significantly impaired the ssDNA-binding and compacting ability of mtSSB, likely by weakening mtSSB ssDNA wrapping efficiency. These features are in line with our molecular modeling of ssDNA on mtSSB showing that the R107Q mutation may destabilize local interactions and results in an electronegative spot that interrupts an ssDNA-interacting-electropositive patch, thus reducing the potential mtSSB-ssDNA interaction sites.
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Affiliation(s)
- Martial Martucci
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Amandine Moretton
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Aleix Tarrés-Solé
- Structural MitoLab, Molecular Biology Institute Barcelona (IBMB-CSIC), Barcelona Science Park, Barcelona 08028, Spain
| | - Virginie Ropars
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Louise Lambert
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Patrick Vernet
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Maria Solà
- Structural MitoLab, Molecular Biology Institute Barcelona (IBMB-CSIC), Barcelona Science Park, Barcelona 08028, Spain
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Geraldine Farge
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Siet van den Wildenberg
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
- Université Clermont Auvergne, CNRS, IRD, Université Jean Monnet Saint Etienne, LMV, F-63000 Clermont-Ferrand, France
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5
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Bernardino Gomes TM, Vincent AE, Menger KE, Stewart JB, Nicholls TJ. Mechanisms and pathologies of human mitochondrial DNA replication and deletion formation. Biochem J 2024; 481:683-715. [PMID: 38804971 PMCID: PMC11346376 DOI: 10.1042/bcj20230262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
Human mitochondria possess a multi-copy circular genome, mitochondrial DNA (mtDNA), that is essential for cellular energy metabolism. The number of copies of mtDNA per cell, and their integrity, are maintained by nuclear-encoded mtDNA replication and repair machineries. Aberrant mtDNA replication and mtDNA breakage are believed to cause deletions within mtDNA. The genomic location and breakpoint sequences of these deletions show similar patterns across various inherited and acquired diseases, and are also observed during normal ageing, suggesting a common mechanism of deletion formation. However, an ongoing debate over the mechanism by which mtDNA replicates has made it difficult to develop clear and testable models for how mtDNA rearrangements arise and propagate at a molecular and cellular level. These deletions may impair energy metabolism if present in a high proportion of the mtDNA copies within the cell, and can be seen in primary mitochondrial diseases, either in sporadic cases or caused by autosomal variants in nuclear-encoded mtDNA maintenance genes. These mitochondrial diseases have diverse genetic causes and multiple modes of inheritance, and show notoriously broad clinical heterogeneity with complex tissue specificities, which further makes establishing genotype-phenotype relationships challenging. In this review, we aim to cover our current understanding of how the human mitochondrial genome is replicated, the mechanisms by which mtDNA replication and repair can lead to mtDNA instability in the form of large-scale rearrangements, how rearranged mtDNAs subsequently accumulate within cells, and the pathological consequences when this occurs.
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Affiliation(s)
- Tiago M. Bernardino Gomes
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- NHS England Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, U.K
| | - Amy E. Vincent
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katja E. Menger
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - James B. Stewart
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
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6
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Eshraghi R, Shafie D, Raisi A, Goleij P, Mirzaei H. Circular RNAs: a small piece in the heart failure puzzle. Funct Integr Genomics 2024; 24:102. [PMID: 38760573 DOI: 10.1007/s10142-024-01386-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 04/15/2024] [Accepted: 05/13/2024] [Indexed: 05/19/2024]
Abstract
Cardiovascular disease, specifically heart failure (HF), remains a significant concern in the realm of healthcare, necessitating the development of new treatments and biomarkers. The RNA family consists of various subgroups, including microRNAs, PIWI-interacting RNAs (piRAN) and long non-coding RNAs, which have shown potential in advancing personalized healthcare for HF patients. Recent research suggests that circular RNAs, a lesser-known subgroup of RNAs, may offer a novel set of targets and biomarkers for HF. This review will discuss the biogenesis of circular RNAs, their unique characteristics relevant to HF, their role in heart function, and their potential use as biomarkers in the bloodstream. Furthermore, future research directions in this field will be outlined. The stability of exosomal circRNAs makes them suitable as biomarkers, pathogenic regulators, and potential treatments for cardiovascular diseases such as atherosclerosis, acute coronary syndrome, ischemia/reperfusion injury, HF, and peripheral artery disease. Herein, we summarized the role of circular RNAs and their exosomal forms in HF diseases.
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Affiliation(s)
- Reza Eshraghi
- Student Research Committee, Kashan University of Medical Sciences, Kashan, Iran
| | - Davood Shafie
- Heart Failure Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Arash Raisi
- Student Research Committee, Kashan University of Medical Sciences, Kashan, Iran
| | - Pouya Goleij
- Department of Genetics, Faculty of Biology, Sana Institute of Higher Education, Sari, Iran.
- USERN Office, Kermanshah University of Medical Sciences, Kermanshah, Iran.
| | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
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7
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Tan BG, Gustafsson CM, Falkenberg M. Mechanisms and regulation of human mitochondrial transcription. Nat Rev Mol Cell Biol 2024; 25:119-132. [PMID: 37783784 DOI: 10.1038/s41580-023-00661-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2023] [Indexed: 10/04/2023]
Abstract
The expression of mitochondrial genes is regulated in response to the metabolic needs of different cell types, but the basic mechanisms underlying this process are still poorly understood. In this Review, we describe how different layers of regulation cooperate to fine tune initiation of both mitochondrial DNA (mtDNA) transcription and replication in human cells. We discuss our current understanding of the molecular mechanisms that drive and regulate transcription initiation from mtDNA promoters, and how the packaging of mtDNA into nucleoids can control the number of mtDNA molecules available for both transcription and replication. Indeed, a unique aspect of the mitochondrial transcription machinery is that it is coupled to mtDNA replication, such that mitochondrial RNA polymerase is additionally required for primer synthesis at mtDNA origins of replication. We discuss how the choice between replication-primer formation and genome-length RNA synthesis is controlled at the main origin of replication (OriH) and how the recent discovery of an additional mitochondrial promoter (LSP2) in humans may change this long-standing model.
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Affiliation(s)
- Benedict G Tan
- Institute for Mitochondrial Diseases and Ageing, Faculty of Medicine and University Hospital Cologne, Cluster of Excellence Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
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8
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Erdinc D, Macao B, Valenzuela S, Lesko N, Naess K, Peter B, Bruhn H, Wedell A, Wredenberg A, Falkenberg M. The disease-causing mutation p.F907I reveals a novel pathogenic mechanism for POLγ-related diseases. Biochim Biophys Acta Mol Basis Dis 2023:166786. [PMID: 37302426 DOI: 10.1016/j.bbadis.2023.166786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/24/2023] [Accepted: 06/07/2023] [Indexed: 06/13/2023]
Abstract
Mutations in the catalytic domain of mitochondrial DNA polymerase γ (POLγ) cause a broad spectrum of clinical conditions. POLγ mutations impair mitochondrial DNA replication, thereby causing deletions and/or depletion of mitochondrial DNA, which in turn impair biogenesis of the oxidative phosphorylation system. We here identify a patient with a homozygous p.F907I mutation in POLγ, manifesting a severe clinical phenotype with developmental arrest and rapid loss of skills from 18 months of age. Magnetic resonance imaging of the brain revealed extensive white matter abnormalities, Southern blot of muscle mtDNA demonstrated depletion of mtDNA and the patient deceased at 23 months of age. Interestingly, the p.F907I mutation does not affect POLγ activity on single-stranded DNA or its proofreading activity. Instead, the mutation affects unwinding of parental double-stranded DNA at the replication fork, impairing the ability of the POLγ to support leading-strand DNA synthesis with the TWINKLE helicase. Our results thus reveal a novel pathogenic mechanism for POLγ-related diseases.
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Affiliation(s)
- Direnis Erdinc
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg SE-40530, Sweden
| | - Bertil Macao
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg SE-40530, Sweden
| | - Sebastian Valenzuela
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg SE-40530, Sweden
| | - Nicole Lesko
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm SE-17177, Sweden; Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Karin Naess
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm SE-17177, Sweden; Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg SE-40530, Sweden
| | - Helene Bruhn
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm SE-17177, Sweden; Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Anna Wedell
- Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden; Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Anna Wredenberg
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm SE-17177, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg SE-40530, Sweden.
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9
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Xu D, Luo L, Huang Y, Lu M, Tang L, Diao Y, Kapranov P. Dynamic Patterns of Mammalian Mitochondrial DNA Replication Uncovered Using SSiNGLe-5'ES. Int J Mol Sci 2023; 24:ijms24119711. [PMID: 37298662 DOI: 10.3390/ijms24119711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/30/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023] Open
Abstract
The proper replication of mitochondrial DNA is key to the maintenance of this crucial organelle. Multiple studies aimed at understanding the mechanisms of replication of the mitochondrial genome have been conducted in the past several decades; however, while highly informative, they were conducted using relatively low-sensitivity techniques. Here, we established a high-throughput approach based on next-generation sequencing to identify replication start sites with nucleotide-level resolution and applied it to the genome of mitochondria from different human and mouse cell types. We found complex and highly reproducible patterns of mitochondrial initiation sites, both previously annotated and newly discovered in this work, that showed differences among different cell types and species. These results suggest that the patterns of the replication initiation sites are dynamic and might reflect, in some yet unknown ways, the complexities of mitochondrial and cellular physiology. Overall, this work suggests that much remains unknown about the details of mitochondrial DNA replication in different biological states, and the method established here opens up a new avenue in the study of the replication of mitochondrial and potentially other genomes.
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Affiliation(s)
- Dongyang Xu
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China
| | - Lingcong Luo
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China
| | - Yu Huang
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China
| | - Meng Lu
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China
| | - Lu Tang
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China
| | - Yong Diao
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China
| | - Philipp Kapranov
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
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10
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Plaza-G A I, Lemishko KM, Crespo R, Truong TQ, Kaguni LS, Cao-García FJ, Ciesielski GL, Ibarra B. Mechanism of strand displacement DNA synthesis by the coordinated activities of human mitochondrial DNA polymerase and SSB. Nucleic Acids Res 2023; 51:1750-1765. [PMID: 36744436 PMCID: PMC9976888 DOI: 10.1093/nar/gkad037] [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: 07/18/2022] [Revised: 12/16/2022] [Accepted: 01/12/2023] [Indexed: 02/07/2023] Open
Abstract
Many replicative DNA polymerases couple DNA replication and unwinding activities to perform strand displacement DNA synthesis, a critical ability for DNA metabolism. Strand displacement is tightly regulated by partner proteins, such as single-stranded DNA (ssDNA) binding proteins (SSBs) by a poorly understood mechanism. Here, we use single-molecule optical tweezers and biochemical assays to elucidate the molecular mechanism of strand displacement DNA synthesis by the human mitochondrial DNA polymerase, Polγ, and its modulation by cognate and noncognate SSBs. We show that Polγ exhibits a robust DNA unwinding mechanism, which entails lowering the energy barrier for unwinding of the first base pair of the DNA fork junction, by ∼55%. However, the polymerase cannot prevent the reannealing of the parental strands efficiently, which limits by ∼30-fold its strand displacement activity. We demonstrate that SSBs stimulate the Polγ strand displacement activity through several mechanisms. SSB binding energy to ssDNA additionally increases the destabilization energy at the DNA junction, by ∼25%. Furthermore, SSB interactions with the displaced ssDNA reduce the DNA fork reannealing pressure on Polγ, in turn promoting the productive polymerization state by ∼3-fold. These stimulatory effects are enhanced by species-specific functional interactions and have significant implications in the replication of the human mitochondrial DNA.
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Affiliation(s)
- Ismael Plaza-G A
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain
| | - Kateryna M Lemishko
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain
| | - Rodrigo Crespo
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Pza. de Ciencias, 1, 28040 Madrid, Spain
| | - Thinh Q Truong
- Department of Chemistry, Auburn University at Montgomery, Montgomery, AL 36117, USA
| | - Laurie S Kaguni
- Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Francisco J Cao-García
- Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, Pza. de Ciencias, 1, 28040 Madrid, Spain
| | - Grzegorz L Ciesielski
- Department of Chemistry, Auburn University at Montgomery, Montgomery, AL 36117, USA.,Department of Biochemistry and Molecular Biology and Center for Mitochondrial Science and Medicine, Michigan State University, East Lansing, MI 48823, USA
| | - Borja Ibarra
- Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA Nanociencia, Faraday 9, 28049 Madrid, Spain.,Nanobiotecnología (IMDEA-Nanociencia), Unidad Asociada al Centro Nacional de Biotecnología (CSIC), 28049 Madrid, Spain
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11
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Feng X, He C. Mammalian DNA N 6-methyladenosine: Challenges and new insights. Mol Cell 2023; 83:343-351. [PMID: 36736309 PMCID: PMC10182828 DOI: 10.1016/j.molcel.2023.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 02/05/2023]
Abstract
DNA N6-methyldeoxyadenosine (6mA) modification was first discovered in Bacterium coli in the 1950s. Over the next several decades, 6mA was recognized as a critical DNA modification in the genomes of prokaryotes and protists. While important in prokaryotes, less is known about the presence and functional roles of DNA 6mA in eukaryotes, particularly in mammals. Taking advantage of recent technology advances that made 6mA detection and sequencing possible, studies over the past several years have brought new insights into 6mA biology in mammals. In this perspective, we present recent progress, discuss challenges, and pose four questions for future research regarding mammalian DNA 6mA.
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Affiliation(s)
- Xinran Feng
- Department of Human Genetics, The University of Chicago, Chicago, IL, USA; Howard Hughes Medical Institute, The University of Chicago, Chicago, IL, USA
| | - Chuan He
- Department of Chemistry, Department of Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA; Howard Hughes Medical Institute, The University of Chicago, Chicago, IL, USA.
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12
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Xu L, Halma MTJ, Wuite GJL. Unravelling How Single-Stranded DNA Binding Protein Coordinates DNA Metabolism Using Single-Molecule Approaches. Int J Mol Sci 2023; 24:ijms24032806. [PMID: 36769124 PMCID: PMC9917605 DOI: 10.3390/ijms24032806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 01/23/2023] [Accepted: 01/28/2023] [Indexed: 02/05/2023] Open
Abstract
Single-stranded DNA-binding proteins (SSBs) play vital roles in DNA metabolism. Proteins of the SSB family exclusively and transiently bind to ssDNA, preventing the DNA double helix from re-annealing and maintaining genome integrity. In the meantime, they interact and coordinate with various proteins vital for DNA replication, recombination, and repair. Although SSB is essential for DNA metabolism, proteins of the SSB family have been long described as accessory players, primarily due to their unclear dynamics and mechanistic interaction with DNA and its partners. Recently-developed single-molecule tools, together with biochemical ensemble techniques and structural methods, have enhanced our understanding of the different coordination roles that SSB plays during DNA metabolism. In this review, we discuss how single-molecule assays, such as optical tweezers, magnetic tweezers, Förster resonance energy transfer, and their combinations, have advanced our understanding of the binding dynamics of SSBs to ssDNA and their interaction with other proteins partners. We highlight the central coordination role that the SSB protein plays by directly modulating other proteins' activities, rather than as an accessory player. Many possible modes of SSB interaction with protein partners are discussed, which together provide a bigger picture of the interaction network shaped by SSB.
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13
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Paolini E, Longo M, Corsini A, Dongiovanni P. The Non-Invasive Assessment of Circulating D-Loop and mt-ccf Levels Opens an Intriguing Spyhole into Novel Approaches for the Tricky Diagnosis of NASH. Int J Mol Sci 2023; 24:ijms24032331. [PMID: 36768654 PMCID: PMC9916898 DOI: 10.3390/ijms24032331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/26/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) is the commonest liver disease worldwide affecting both adults and children. Nowadays, no therapeutic strategies have been approved for NAFLD management, and hepatic biopsy remains the gold standard procedure for its diagnosis. NAFLD is a multifactorial disease whose pathogenesis is affected by environmental and genetic factors, and it covers a spectrum of conditions ranging from simple steatosis up to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Several studies underlined the urgent need to develop an NAFLD risk prediction model based on genetics, biochemical indicators, and metabolic disorders. The loss of mitochondrial dynamics represents a typical feature of progressive NAFLD. The imbalance of mitochondrial lifecycle together with the impairment of mitochondrial biomass and function trigger oxidative stress, which in turn damages mitochondrial DNA (mtDNA). We recently demonstrated that the main genetic predictors of NAFLD led to mitochondrial dysfunction. Moreover, emerging evidence shows that variations in the displacement loop (D-loop) region impair mtDNA replication, and they have been associated with advanced NAFLD. Finally, lower levels of mitophagy foster the overload of damaged mitochondria, resulting in the release of cell-free circulating mitochondrial DNA (mt-ccf) that exacerbates liver injury. Thus, in this review we summarized what is known about D-loop region alterations and mt-ccf content during NAFLD to propose them as novel non-invasive biomarkers.
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Affiliation(s)
- Erika Paolini
- General Medicine and Metabolic Diseases, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122 Milan, Italy
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20133 Milano, Italy
| | - Miriam Longo
- General Medicine and Metabolic Diseases, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122 Milan, Italy
- Department of Clinical Sciences and Community Health, Università degli Studi di Milano, 20122 Milano, Italy
| | - Alberto Corsini
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, 20133 Milano, Italy
- IRCCS Multimedica, 20099 Milan, Italy
| | - Paola Dongiovanni
- General Medicine and Metabolic Diseases, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Via Francesco Sforza 35, 20122 Milan, Italy
- Correspondence: ; Tel.: +39-02-5503-3467; Fax: +39-02-5032-0296
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14
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The N-terminal domain of human mitochondrial helicase Twinkle has DNA-binding activity crucial for supporting processive DNA synthesis by polymerase γ. J Biol Chem 2022; 299:102797. [PMID: 36528058 PMCID: PMC9860392 DOI: 10.1016/j.jbc.2022.102797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/30/2022] [Accepted: 12/03/2022] [Indexed: 12/15/2022] Open
Abstract
Twinkle is the ring-shaped replicative helicase within the human mitochondria with high homology to bacteriophage T7 gp4 helicase-primase. Unlike many orthologs of Twinkle, the N-terminal domain (NTD) of human Twinkle has lost its primase activity through evolutionarily acquired mutations. The NTD has no demonstrated activity thus far; its role has remained unclear. Here, we biochemically characterize the isolated NTD and C-terminal domain (CTD) with linker to decipher their contributions to full-length Twinkle activities. This novel CTD construct hydrolyzes ATP, has weak DNA unwinding activity, and assists DNA polymerase γ (Polγ)-catalyzed strand-displacement synthesis on short replication forks. However, CTD fails to promote multikilobase length product formation by Polγ in rolling-circle DNA synthesis. Thus, CTD retains all the motor functions but struggles to implement them for processive translocation. We show that NTD has DNA-binding activity, and its presence stabilizes Twinkle oligomerization. CTD oligomerizes on its own, but the loss of NTD results in heterogeneously sized oligomeric species. The CTD also exhibits weaker and salt-sensitive DNA binding compared with full-length Twinkle. Based on these results, we propose that NTD directly contributes to DNA binding and holds the DNA in place behind the central channel of the CTD like a "doorstop," preventing helicase slippages and sustaining processive unwinding. Consistent with this model, mitochondrial single-stranded DNA-binding protein (mtSSB) compensate for the NTD loss and partially restore kilobase length DNA synthesis by CTD and Polγ. The implications of our studies are foundational for understanding the mechanisms of disease-causing Twinkle mutants that lie in the NTD.
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15
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Optical Tweezers to Force Information out of Biological and Synthetic Systems One Molecule at a Time. BIOPHYSICA 2022. [DOI: 10.3390/biophysica2040047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Over the last few decades, in vitro single-molecule manipulation techniques have enabled the use of force and displacement as controlled variables in biochemistry. Measuring the effect of mechanical force on the real-time kinetics of a biological process gives us access to the rates, equilibrium constants and free-energy landscapes of the mechanical steps of the reaction; this information is not accessible by ensemble assays. Optical tweezers are the current method of choice in single-molecule manipulation due to their versatility, high force and spatial and temporal resolutions. The aim of this review is to describe the contributions of our lab in the single-molecule manipulation field. We present here several optical tweezers assays refined in our laboratory to probe the dynamics and mechano-chemical properties of biological molecular motors and synthetic molecular devices at the single-molecule level.
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16
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Memon AA, Vats S, Sundquist J, Li Y, Sundquist K. Mitochondrial DNA Copy Number: Linking Diabetes and Cancer. Antioxid Redox Signal 2022; 37:1168-1190. [PMID: 36169625 DOI: 10.1089/ars.2022.0100] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent Advances: Various studies have suggested that mitochondrial DNA copy number (mtDNA-CN), a surrogate biomarker of mitochondrial dysfunction, is an easily quantifiable biomarker for chronic diseases, including diabetes and cancer. However, current knowledge is limited, and the results are controversial. This has been attributed mainly to methodology and study design. Critical Issues: The incidence of diabetes and cancer has increased significantly in recent years. Moreover, type 2 diabetes (T2D) has been shown to be a risk factor for cancer. mtDNA-CN has been associated with both T2D and cancer. However, it is not known whether mtDNA-CN plays any role in the association between T2D and cancer. Significance: In this review, we have discussed mtDNA-CN in diabetes and cancer, and reviewed the literature and methodology used in published studies so far. Based on the literature review, we have speculated how mtDNA-CN may act as a link between diabetes and cancer. Furthermore, we have provided some recommendations for reliable translation of mtDNA-CN as a biomarker. Future Directions: Further research is required to elucidate the role of mtDNA-CN in the association between T2D and cancer. If established, early lifestyle interventions, such as physical activity and diet control that improve mitochondrial function, may help preventing cancer in patients with T2D. Antioxid. Redox Signal. 37, 1168-1190.
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Affiliation(s)
- Ashfaque A Memon
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Sakshi Vats
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Jan Sundquist
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Yanni Li
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
| | - Kristina Sundquist
- Center for Primary Health Care Research, Lund University/Region Skåne, Malmö, Sweden
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17
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Li Z, Kaur P, Lo CY, Chopra N, Smith J, Wang H, Gao Y. Structural and dynamic basis of DNA capture and translocation by mitochondrial Twinkle helicase. Nucleic Acids Res 2022; 50:11965-11978. [PMID: 36400570 PMCID: PMC9723800 DOI: 10.1093/nar/gkac1089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 10/21/2022] [Accepted: 10/26/2022] [Indexed: 11/21/2022] Open
Abstract
Twinkle is a mitochondrial replicative helicase which can self-load onto and unwind mitochondrial DNA. Nearly 60 mutations on Twinkle have been linked to human mitochondrial diseases. Using cryo-electron microscopy (cryo-EM) and high-speed atomic force microscopy (HS-AFM), we obtained the atomic-resolution structure of a vertebrate Twinkle homolog with DNA and captured in real-time how Twinkle is self-loaded onto DNA. Our data highlight the important role of the non-catalytic N-terminal domain of Twinkle. The N-terminal domain directly contacts the C-terminal helicase domain, and the contact interface is a hotspot for disease-related mutations. Mutations at the interface destabilize Twinkle hexamer and reduce helicase activity. With HS-AFM, we observed that a highly dynamic Twinkle domain, which is likely to be the N-terminal domain, can protrude ∼5 nm to transiently capture nearby DNA and initialize Twinkle loading onto DNA. Moreover, structural analysis and subunit doping experiments suggest that Twinkle hydrolyzes ATP stochastically, which is distinct from related helicases from bacteriophages.
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Affiliation(s)
- Zhuo Li
- BioSciences Department, Rice University, Houston, TX 77005, USA
| | - Parminder Kaur
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
| | - Chen-Yu Lo
- BioSciences Department, Rice University, Houston, TX 77005, USA
| | - Neil Chopra
- BioSciences Department, Rice University, Houston, TX 77005, USA
| | - Jamie Smith
- BioSciences Department, Rice University, Houston, TX 77005, USA
| | - Hong Wang
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC 27695, USA
- Toxicology Program, North Carolina State University, Raleigh, NC 27695, USA
| | - Yang Gao
- BioSciences Department, Rice University, Houston, TX 77005, USA
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18
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Almannai M, El-Hattab AW, Azamian MS, Ali M, Scaglia F. Mitochondrial DNA maintenance defects: potential therapeutic strategies. Mol Genet Metab 2022; 137:40-48. [PMID: 35914366 PMCID: PMC10401187 DOI: 10.1016/j.ymgme.2022.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/03/2022] [Accepted: 07/03/2022] [Indexed: 10/17/2022]
Abstract
Mitochondrial DNA (mtDNA) replication depends on the mitochondrial import of hundreds of nuclear encoded proteins that control the mitochondrial genome maintenance and integrity. Defects in these processes result in an expanding group of disorders called mtDNA maintenance defects that are characterized by mtDNA depletion and/or multiple mtDNA deletions with variable phenotypic manifestations. As it applies for mitochondrial disorders in general, current treatment options for mtDNA maintenance defects are limited. Lately, with the development of model organisms, improved understanding of the pathophysiology of these disorders, and a better knowledge of their natural history, the number of preclinical studies and existing and planned clinical trials has been increasing. In this review, we discuss recent preclinical studies and current and future clinical trials concerning potential therapeutic options for the different mtDNA maintenance defects.
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Affiliation(s)
- Mohammed Almannai
- Genetics and Precision Medicine Department (GPM), King Abdullah Specialized Children's Hospital (KASCH), King Abdulaziz Medical City, Ministry of National Guard Health Affairs (MNG-HA), Riyadh, Saudi Arabia
| | - Ayman W El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Mahshid S Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - May Ali
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA; Joint BCM-CUHK Center of Medical Genetics, Prince of Wales Hospital, Shatin, Hong Kong.
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19
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Abd Radzak SM, Mohd Khair SZN, Ahmad F, Patar A, Idris Z, Mohamed Yusoff AA. Insights regarding mitochondrial DNA copy number alterations in human cancer (Review). Int J Mol Med 2022; 50:104. [PMID: 35713211 PMCID: PMC9304817 DOI: 10.3892/ijmm.2022.5160] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 05/26/2022] [Indexed: 11/25/2022] Open
Abstract
Mitochondria are the critical organelles involved in various cellular functions. Mitochondrial biogenesis is activated by multiple cellular mechanisms which require a synchronous regulation between mitochondrial DNA (mtDNA) and nuclear DNA (nDNA). The mitochondrial DNA copy number (mtDNA-CN) is a proxy indicator for mitochondrial activity, and its alteration reflects mitochondrial biogenesis and function. Despite the precise mechanisms that modulate the amount and composition of mtDNA, which have not been fully elucidated, mtDNA-CN is known to influence numerous cellular pathways that are associated with cancer and as well as multiple other diseases. In addition, the utility of current technology in measuring mtDNA-CN contributes to its extensive assessment of diverse traits and tumorigenesis. The present review provides an overview of mtDNA-CN variations across human cancers and an extensive summary of the existing knowledge on the regulation and machinery of mtDNA-CN. The current information on the advanced methods used for mtDNA-CN assessment is also presented.
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Affiliation(s)
- Siti Muslihah Abd Radzak
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan 16150, Malaysia
| | - Siti Zulaikha Nashwa Mohd Khair
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan 16150, Malaysia
| | - Farizan Ahmad
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan 16150, Malaysia
| | - Azim Patar
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan 16150, Malaysia
| | - Zamzuri Idris
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan 16150, Malaysia
| | - Abdul Aziz Mohamed Yusoff
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan 16150, Malaysia
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20
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Lu D, Chatterjee S, Xiao K, Riedel I, Huang CK, Costa A, Cushman S, Neufeldt D, Rode L, Schmidt A, Juchem M, Leonardy J, Büchler G, Blume J, Gern OL, Kalinke U, Wen Tan WL, Foo R, Vink A, van Laake LW, van der Meer P, Bär C, Thum T. A circular RNA derived from the insulin receptor locus protects against doxorubicin-induced cardiotoxicity. Eur Heart J 2022; 43:4496-4511. [PMID: 35758064 PMCID: PMC9637424 DOI: 10.1093/eurheartj/ehac337] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/30/2022] [Accepted: 06/09/2022] [Indexed: 12/14/2022] Open
Abstract
AIMS Cardiotoxicity leading to heart failure (HF) is a growing problem in many cancer survivors. As specific treatment strategies are not available, RNA discovery pipelines were employed and a new and powerful circular RNA (circRNA)-based therapy was developed for the treatment of doxorubicin-induced HF. METHODS AND RESULTS The circRNA sequencing was applied and the highly species-conserved circRNA insulin receptor (Circ-INSR) was identified, which participates in HF processes, including those provoked by cardiotoxic anti-cancer treatments. Chemotherapy-provoked cardiotoxicity leads to the down-regulation of Circ-INSR in rodents and patients, which mechanistically contributes to cardiomyocyte cell death, cardiac dysfunction, and mitochondrial damage. In contrast, Circ-INSR overexpression prevented doxorubicin-mediated cardiotoxicity in both rodent and human cardiomyocytes in vitro and in a mouse model of chronic doxorubicin cardiotoxicity. Breast cancer type 1 susceptibility protein (Brca1) was identified as a regulator of Circ-INSR expression. Detailed transcriptomic and proteomic analyses revealed that Circ-INSR regulates apoptotic and metabolic pathways in cardiomyocytes. Circ-INSR physically interacts with the single-stranded DNA-binding protein (SSBP1) mediating its cardioprotective effects under doxorubicin stress. Importantly, in vitro transcribed and circularized Circ-INSR mimics also protected against doxorubicin-induced cardiotoxicity. CONCLUSION Circ-INSR is a highly conserved non-coding RNA which is down-regulated during cardiotoxicity and cardiac remodelling. Adeno-associated virus and circRNA mimics-based Circ-INSR overexpression prevent and reverse doxorubicin-mediated cardiomyocyte death and improve cardiac function. The results of this study highlight a novel and translationally important Circ-INSR-based therapeutic approach for doxorubicin-induced cardiac dysfunction.
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Affiliation(s)
| | | | | | - Isabelle Riedel
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Cheng-Kai Huang
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Alessia Costa
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany,REBIRTH Center for Translational Regenerative Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Sarah Cushman
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Dimyana Neufeldt
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Laura Rode
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Arne Schmidt
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Malte Juchem
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Julia Leonardy
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Gwen Büchler
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Jonas Blume
- Institute of Molecular and Translational Therapeutic Strategies, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Olivia-Luise Gern
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, Feodor-Lynen-Straße 7, Hannover 30625, Germany,Department of Pathology, University of Veterinary Medicine Hannover, Foundation, Bünteweg 2, Hannover 30559, Germany
| | - Ulrich Kalinke
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, Feodor-Lynen-Straße 7, Hannover 30625, Germany,Cluster of Excellence—Resolving Infection Susceptibility (RESIST), Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany
| | - Wilson Lek Wen Tan
- Cardiovascular Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Centre for Translational Medicine, 14 Medical Drive, Level 8, Singapore 117599, Republic of Singapore
| | - Roger Foo
- Cardiovascular Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Centre for Translational Medicine, 14 Medical Drive, Level 8, Singapore 117599, Republic of Singapore
| | - Aryan Vink
- Department of Pathology, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584, The Netherlands
| | - Linda W van Laake
- Department of Cardiology and Regenerative Medicine Center, University Medical Centre Utrecht, Heidelberglaan 100, Utrecht 3584, The Netherlands
| | - Peter van der Meer
- Department of Cardiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen 9713, The Netherlands
| | - Christian Bär
- Corresponding authors. Tel: +49 511 532 5272, (T.T.); Tel: +49 511 532 2883, (C.B.)
| | - Thomas Thum
- Corresponding authors. Tel: +49 511 532 5272, (T.T.); Tel: +49 511 532 2883, (C.B.)
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21
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Hao J, Sun M, Li D, Zhang T, Li J, Zhou D. An IFI6-based hydrogel promotes the healing of radiation-induced skin injury through regulation of the HSF1 activity. J Nanobiotechnology 2022; 20:288. [PMID: 35717249 PMCID: PMC9206756 DOI: 10.1186/s12951-022-01466-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/17/2022] [Indexed: 12/21/2022] Open
Abstract
Radiation-induced skin injury (RISI) is a common complication of radiotherapy. Interferon-alpha inducible protein 6 (IFI6) significantly reduces the radiation sensitivity of HaCaT cells. Sodium alginate (SA) has substantial moisturizing properties. Graphene oxide (GO) is a suitable substrate with physical antibacterial properties. Therefore, we designed materials to modify IFI6 using the biogule of polydopamine (PDA) connected to GO/SA. The structure, size, morphology, and elemental compositions of IFI6-PDA@GO/SA were analyzed. Cytological studies suggested that IFI6-PDA@GO/SA is non-toxic to HaCaT cells, with antibacterial properties. It promotes migration and vascularization and inhibits apoptosis. These cells express IFI6 after irradiation. The mouse model suggested that IFI6-PDA@GO/SA promotes wound healing and reduces reactive oxygen species expression. IFI6-PDA@GO/SA accelerates RISI healing, possibly by initiating the SSBP1/HSF1 signaling pathway. In addition, IFI6-PDA@GO/SA improves the immune microenvironment. This study constitutes the first use of IFI6 as a RISI wound-healing material.
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Affiliation(s)
- Jie Hao
- Department of Oncology, Southwest Hospital, Army Medical University, Chongqing, 400038, China
| | - Mengyi Sun
- Department of Rehabilitation, The Second Affiliated Hospital of Xinjiang Medical University, Ürümqi, 830092, China
| | - Dong Li
- Department of Oncology, The General Hospital of Western Theater Command of PLA, Chengdu, 610083, China
| | - Tao Zhang
- Department of Oncology, The General Hospital of Western Theater Command of PLA, Chengdu, 610083, China.
| | - Jianjun Li
- Department of Oncology, Southwest Hospital, Army Medical University, Chongqing, 400038, China.
| | - Daijun Zhou
- Department of Oncology, Southwest Hospital, Army Medical University, Chongqing, 400038, China. .,Department of Oncology, The General Hospital of Western Theater Command of PLA, Chengdu, 610083, China.
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22
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Almannai M, Salah A, El-Hattab AW. Mitochondrial Membranes and Mitochondrial Genome: Interactions and Clinical Syndromes. MEMBRANES 2022; 12:membranes12060625. [PMID: 35736332 PMCID: PMC9229594 DOI: 10.3390/membranes12060625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/06/2022] [Accepted: 06/14/2022] [Indexed: 11/16/2022]
Abstract
Mitochondria are surrounded by two membranes; the outer mitochondrial membrane and the inner mitochondrial membrane. They are unique organelles since they have their own DNA, the mitochondrial DNA (mtDNA), which is replicated continuously. Mitochondrial membranes have direct interaction with mtDNA and are therefore involved in organization of the mitochondrial genome. They also play essential roles in mitochondrial dynamics and the supply of nucleotides for mtDNA synthesis. In this review, we will discuss how the mitochondrial membranes interact with mtDNA and how this interaction is essential for mtDNA maintenance. We will review different mtDNA maintenance disorders that result from defects in this crucial interaction. Finally, we will review therapeutic approaches relevant to defects in mitochondrial membranes.
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Affiliation(s)
- Mohammed Almannai
- Genetics and Precision Medicine Department, King Abdullah Specialized Children Hospital, Riyadh P.O. Box 22490, Saudi Arabia
- Correspondence:
| | - Azza Salah
- Department of Pediatrics, University Hospital Sharjah, Sharjah P.O. Box 72772, United Arab Emirates;
| | - Ayman W. El-Hattab
- Department of Pediatrics, University Hospital Sharjah, Sharjah P.O. Box 72772, United Arab Emirates;
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates;
- Genetics and Metabolic Department, KidsHeart Medical Center, Abu Dhabi P.O. Box 505193, United Arab Emirates
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23
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Liu C, Fu Z, Wu S, Wang X, Zhang S, Chu C, Hong Y, Wu W, Chen S, Jiang Y, Wu Y, Song Y, Liu Y, Guo X. Mitochondrial HSF1 triggers mitochondrial dysfunction and neurodegeneration in Huntington's disease. EMBO Mol Med 2022; 14:e15851. [PMID: 35670111 PMCID: PMC9260212 DOI: 10.15252/emmm.202215851] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 05/10/2022] [Accepted: 05/10/2022] [Indexed: 12/18/2022] Open
Affiliation(s)
- Chunyue Liu
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Zixing Fu
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Shanshan Wu
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Xiaosong Wang
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Shengrong Zhang
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Chu Chu
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Yuan Hong
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Wenbo Wu
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Shengqi Chen
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Yueqing Jiang
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
| | - Yang Wu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Key Laboratory of Magnetic Resonance in Biological Systems Wuhan Center for Magnetic Resonance, Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan China
| | - Yongbo Song
- Department of Pharmacology Shenyang Pharmaceutical University Shenyang China
| | - Yan Liu
- State Key Laboratory of Reproductive Medicine Interdisciplinary InnoCenter for Organoids Institute for Stem Cell and Neural Regeneration School of Pharmacy Nanjing Medical University Nanjing China
| | - Xing Guo
- State Key Laboratory of Reproductive Medicine Key Laboratory of Human Functional Genomics of Jiangsu Province Department of Neurobiology Interdisciplinary InnoCenter for Organoids School of Basic Medical Sciences Nanjing Medical University Nanjing China
- Department of Endocrinology Sir Run Run Hospital Nanjing Medical University Nanjing Jiangsu China
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24
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Roy A, Kandettu A, Ray S, Chakrabarty S. Mitochondrial DNA replication and repair defects: Clinical phenotypes and therapeutic interventions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148554. [PMID: 35341749 DOI: 10.1016/j.bbabio.2022.148554] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 03/06/2022] [Accepted: 03/16/2022] [Indexed: 12/15/2022]
Abstract
Mitochondria is a unique cellular organelle involved in multiple cellular processes and is critical for maintaining cellular homeostasis. This semi-autonomous organelle contains its circular genome - mtDNA (mitochondrial DNA), that undergoes continuous cycles of replication and repair to maintain the mitochondrial genome integrity. The majority of the mitochondrial genes, including mitochondrial replisome and repair genes, are nuclear-encoded. Although the repair machinery of mitochondria is quite efficient, the mitochondrial genome is highly susceptible to oxidative damage and other types of exogenous and endogenous agent-induced DNA damage, due to the absence of protective histones and their proximity to the main ROS production sites. Mutations in replication and repair genes of mitochondria can result in mtDNA depletion and deletions subsequently leading to mitochondrial genome instability. The combined action of mutations and deletions can result in compromised mitochondrial genome maintenance and lead to various mitochondrial disorders. Here, we review the mechanism of mitochondrial DNA replication and repair process, key proteins involved, and their altered function in mitochondrial disorders. The focus of this review will be on the key genes of mitochondrial DNA replication and repair machinery and the clinical phenotypes associated with mutations in these genes.
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Affiliation(s)
- Abhipsa Roy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Amoolya Kandettu
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Swagat Ray
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln LN6 7TS, United Kingdom
| | - Sanjiban Chakrabarty
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
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25
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Abstract
In the course of its short history, mitochondrial DNA (mtDNA) has made a long journey from obscurity to the forefront of research on major biological processes. mtDNA alterations have been found in all major disease groups, and their significance remains the subject of intense research. Despite remarkable progress, our understanding of the major aspects of mtDNA biology, such as its replication, damage, repair, transcription, maintenance, etc., is frustratingly limited. The path to better understanding mtDNA and its role in cells, however, remains torturous and not without errors, which sometimes leave a long trail of controversy behind them. This review aims to provide a brief summary of our current knowledge of mtDNA and highlight some of the controversies that require attention from the mitochondrial research community.
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Affiliation(s)
- Inna Shokolenko
- Department of Biomedical Sciences, Pat Capps Covey College of Allied Health Professions, University of South Alabama, Mobile, AL 36688, USA
| | - Mikhail Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, AL 36688, USA
- Correspondence:
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26
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Mitochondria homeostasis: Biology and involvement in hepatic steatosis to NASH. Acta Pharmacol Sin 2022; 43:1141-1155. [PMID: 35105958 PMCID: PMC9061859 DOI: 10.1038/s41401-022-00864-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 01/09/2022] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial biology and behavior are central to the physiology of liver. Multiple mitochondrial quality control mechanisms remodel mitochondrial homeostasis under physiological and pathological conditions. Mitochondrial dysfunction and damage induced by overnutrition lead to oxidative stress, inflammation, liver cell death, and collagen production, which advance hepatic steatosis to nonalcoholic steatohepatitis (NASH). Accumulating evidence suggests that specific interventions that target mitochondrial homeostasis, including energy metabolism, antioxidant effects, and mitochondrial quality control, have emerged as promising strategies for NASH treatment. However, clinical translation of these findings is challenging due to the complex and unclear mechanisms of mitochondrial homeostasis in the pathophysiology of NASH.
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27
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Silva-Pinheiro P, Minczuk M. The potential of mitochondrial genome engineering. Nat Rev Genet 2022; 23:199-214. [PMID: 34857922 DOI: 10.1038/s41576-021-00432-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2021] [Indexed: 12/19/2022]
Abstract
Mitochondria are subject to unique genetic control by both nuclear DNA and their own genome, mitochondrial DNA (mtDNA), of which each mitochondrion contains multiple copies. In humans, mutations in mtDNA can lead to devastating, heritable, multi-system diseases that display different tissue-specific presentation at any stage of life. Despite rapid advances in nuclear genome engineering, for years, mammalian mtDNA has remained resistant to genetic manipulation, hampering our ability to understand the mechanisms that underpin mitochondrial disease. Recent developments in the genetic modification of mammalian mtDNA raise the possibility of using genome editing technologies, such as programmable nucleases and base editors, for the treatment of hereditary mitochondrial disease.
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Affiliation(s)
| | - Michal Minczuk
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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28
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Abstract
R-loops forming inadvertently during transcription can threaten genome stability, but R-loops are also formed intentionally, as a means of regulating transcription and other aspects of DNA metabolism. The study of R-loops in mitochondria is in its infancy, and yet there is already clear evidence that they are predominantly located in the major regulatory region of the mammalian mitochondrial genome. Here, we describe how mitochondrial R-loops have been characterized to date, with the emphasis on the problems of their being extremely labile, and how to minimize their loss during extraction. The oft-overlooked issues of RNA-DNA hybrids not being synonymous with R-loops, and adventitious RNA hybridization to DNA, are tackled head on; and possible new approaches are described and placed in the context of future research lines that could reveal the detailed roles of R-loops in the metabolism of mitochondrial DNA.
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Affiliation(s)
- Ian J Holt
- Biodonostia Health Research Institute, San Sebastián, Spain.
- CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), Madrid, Spain.
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
- Universidad de País Vasco, Bilbao, Spain.
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29
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Kosar M, Piccini D, Foiani M, Giannattasio M. A rapid method to visualize human mitochondrial DNA replication through rotary shadowing and transmission electron microscopy. Nucleic Acids Res 2021; 49:e121. [PMID: 34500456 PMCID: PMC8643652 DOI: 10.1093/nar/gkab770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 08/15/2021] [Accepted: 08/26/2021] [Indexed: 11/21/2022] Open
Abstract
We report a rapid experimental procedure based on high-density in vivo psoralen inter-strand DNA cross-linking coupled to spreading of naked purified DNA, positive staining, low-angle rotary shadowing, and transmission electron microscopy (TEM) that allows quick visualization of the dynamic of heavy strand (HS) and light strand (LS) human mitochondrial DNA replication. Replication maps built on linearized mitochondrial genomes and optimized rotary shadowing conditions enable clear visualization of the progression of the mitochondrial DNA synthesis and visualization of replication intermediates carrying long single-strand DNA stretches. One variant of this technique, called denaturing spreading, allowed the inspection of the fine chromatin structure of the mitochondrial genome and was applied to visualize the in vivo three-strand DNA structure of the human mitochondrial D-loop intermediate with unprecedented clarity.
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Affiliation(s)
- Martin Kosar
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy
| | - Daniele Piccini
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy
| | - Marco Foiani
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy.,Dipartimento di Oncologia & Emato-Oncologia, Università degli Studi di Milano, Milano, Italy
| | - Michele Giannattasio
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milano, Italy.,Dipartimento di Oncologia & Emato-Oncologia, Università degli Studi di Milano, Milano, Italy
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30
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Sanchez-Contreras M, Sweetwyne MT, Kohrn BF, Tsantilas KA, Hipp MJ, Schmidt EK, Fredrickson J, Whitson JA, Campbell MD, Rabinovitch PS, Marcinek DJ, Kennedy SR. A replication-linked mutational gradient drives somatic mutation accumulation and influences germline polymorphisms and genome composition in mitochondrial DNA. Nucleic Acids Res 2021; 49:11103-11118. [PMID: 34614167 PMCID: PMC8565317 DOI: 10.1093/nar/gkab901] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/10/2021] [Accepted: 09/22/2021] [Indexed: 11/22/2022] Open
Abstract
Mutations in mitochondrial DNA (mtDNA) cause maternally inherited diseases, while somatic mutations are linked to common diseases of aging. Although mtDNA mutations impact health, the processes that give rise to them are under considerable debate. To investigate the mechanism by which de novo mutations arise, we analyzed the distribution of naturally occurring somatic mutations across the mouse and human mtDNA obtained by Duplex Sequencing. We observe distinct mutational gradients in G→A and T→C transitions delimited by the light-strand origin and the mitochondrial Control Region (mCR). The gradient increases unequally across the mtDNA with age and is lost in the absence of DNA polymerase γ proofreading activity. In addition, high-resolution analysis of the mCR shows that important regulatory elements exhibit considerable variability in mutation frequency, consistent with them being mutational ‘hot-spots’ or ‘cold-spots’. Collectively, these patterns support genome replication via a deamination prone asymmetric strand-displacement mechanism as the fundamental driver of mutagenesis in mammalian DNA. Moreover, the distribution of mtDNA single nucleotide polymorphisms in humans and the distribution of bases in the mtDNA across vertebrate species mirror this gradient, indicating that replication-linked mutations are likely the primary source of inherited polymorphisms that, over evolutionary timescales, influences genome composition during speciation.
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Affiliation(s)
- Monica Sanchez-Contreras
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Mariya T Sweetwyne
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Brendan F Kohrn
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | | | - Michael J Hipp
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Elizabeth K Schmidt
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Jeanne Fredrickson
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Jeremy A Whitson
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - Matthew D Campbell
- Department of Radiology, University of Washington, Seattle, WA 98195, USA
| | - Peter S Rabinovitch
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
| | - David J Marcinek
- Department of Radiology, University of Washington, Seattle, WA 98195, USA
| | - Scott R Kennedy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
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31
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Inatomi T, Matsuda S, Ishiuchi T, Do Y, Nakayama M, Abe S, Kasho K, Wanrooij S, Nakada K, Ichiyanagi K, Sasaki H, Yasukawa T, Kang D. TFB2M and POLRMT are essential for mammalian mitochondrial DNA replication. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1869:119167. [PMID: 34744028 DOI: 10.1016/j.bbamcr.2021.119167] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 10/13/2021] [Accepted: 10/13/2021] [Indexed: 12/24/2022]
Abstract
Two classes of replication intermediates have been observed from mitochondrial DNA (mtDNA) in many mammalian tissue and cells with two-dimensional agarose gel electrophoresis. One is assigned to leading-strand synthesis in the absence of synchronous lagging-strand synthesis (strand-asynchronous replication), and the other has properties of coupled leading- and lagging-strand synthesis (strand-coupled replication). While strand-asynchronous replication is primed by long noncoding RNA synthesized from a defined transcription initiation site, little is known about the commencement of strand-coupled replication. To investigate it, we attempted to abolish strand-asynchronous replication in cultured human cybrid cells by knocking out the components of the transcription initiation complexes, mitochondrial transcription factor B2 (TFB2M/mtTFB2) and mitochondrial RNA polymerase (POLRMT/mtRNAP). Unexpectedly, removal of either protein resulted in complete mtDNA loss, demonstrating for the first time that TFB2M and POLRMT are indispensable for the maintenance of human mtDNA. Moreover, a lack of TFB2M could not be compensated for by mitochondrial transcription factor B1 (TFB1M/mtTFB1). These findings indicate that TFB2M and POLRMT are crucial for the priming of not only strand-asynchronous but also strand-coupled replication, providing deeper insights into the molecular basis of mtDNA replication initiation.
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Affiliation(s)
- Teppei Inatomi
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Shigeru Matsuda
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan; Department of Modomics Biology and Medicine, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryocho, Aoba-ku, Sendai-shi, Miyagi 980-8575, Japan
| | - Takashi Ishiuchi
- Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Yura Do
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Masunari Nakayama
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Shusaku Abe
- Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Kazutoshi Kasho
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Sjoerd Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Kazuto Nakada
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8572, Japan
| | - Kenji Ichiyanagi
- Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya-shi, Aichi 464-8601, Japan
| | - Hiroyuki Sasaki
- Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Takehiro Yasukawa
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan; Department of Pathology and Oncology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
| | - Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
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32
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Allkanjari K, Baldock RA. Beyond base excision repair: an evolving picture of mitochondrial DNA repair. Biosci Rep 2021; 41:BSR20211320. [PMID: 34608928 PMCID: PMC8527207 DOI: 10.1042/bsr20211320] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/29/2021] [Accepted: 10/04/2021] [Indexed: 12/11/2022] Open
Abstract
Mitochondria are highly specialised organelles required for key cellular processes including ATP production through cellular respiration and controlling cell death via apoptosis. Unlike other organelles, mitochondria contain their own DNA genome which encodes both protein and RNA required for cellular respiration. Each cell may contain hundreds to thousands of copies of the mitochondrial genome, which is essential for normal cellular function - deviation of mitochondrial DNA (mtDNA) copy number is associated with cellular ageing and disease. Furthermore, mtDNA lesions can arise from both endogenous or exogenous sources and must either be tolerated or corrected to preserve mitochondrial function. Importantly, replication of damaged mtDNA can lead to stalling and introduction of mutations or genetic loss, mitochondria have adapted mechanisms to repair damaged DNA. These mechanisms rely on nuclear-encoded DNA repair proteins that are translocated into the mitochondria. Despite the presence of many known nuclear DNA repair proteins being found in the mitochondrial proteome, it remains to be established which DNA repair mechanisms are functional in mammalian mitochondria. Here, we summarise the existing and emerging research, alongside examining proteomic evidence, demonstrating that mtDNA damage can be repaired using Base Excision Repair (BER), Homologous Recombination (HR) and Microhomology-mediated End Joining (MMEJ). Critically, these repair mechanisms do not operate in isolation and evidence for interplay between pathways and repair associated with replication is discussed. Importantly, characterising non-canonical functions of key proteins and understanding the bespoke pathways used to tolerate, repair or bypass DNA damage will be fundamental in fully understanding the causes of mitochondrial genome mutations and mitochondrial dysfunction.
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Affiliation(s)
- Kathrin Allkanjari
- Formerly: Solent University Southampton, East Park Terrace, Southampton, SO14 0YN, UK
| | - Robert A. Baldock
- School of Natural and Social Sciences, University of Gloucestershire, Francis Close Hall, Swindon Road, Cheltenham GL50 4AZ, UK
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33
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Moreira JD, Gopal DM, Kotton DN, Fetterman JL. Gaining Insight into Mitochondrial Genetic Variation and Downstream Pathophysiology: What Can i(PSCs) Do? Genes (Basel) 2021; 12:1668. [PMID: 34828274 PMCID: PMC8624338 DOI: 10.3390/genes12111668] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are specialized organelles involved in energy production that have retained their own genome throughout evolutionary history. The mitochondrial genome (mtDNA) is maternally inherited and requires coordinated regulation with nuclear genes to produce functional enzyme complexes that drive energy production. Each mitochondrion contains 5-10 copies of mtDNA and consequently, each cell has several hundreds to thousands of mtDNAs. Due to the presence of multiple copies of mtDNA in a mitochondrion, mtDNAs with different variants may co-exist, a condition called heteroplasmy. Heteroplasmic variants can be clonally expanded, even in post-mitotic cells, as replication of mtDNA is not tied to the cell-division cycle. Heteroplasmic variants can also segregate during germ cell formation, underlying the inheritance of some mitochondrial mutations. Moreover, the uneven segregation of heteroplasmic variants is thought to underlie the heterogeneity of mitochondrial variation across adult tissues and resultant differences in the clinical presentation of mitochondrial disease. Until recently, however, the mechanisms mediating the relation between mitochondrial genetic variation and disease remained a mystery, largely due to difficulties in modeling human mitochondrial genetic variation and diseases. The advent of induced pluripotent stem cells (iPSCs) and targeted gene editing of the nuclear, and more recently mitochondrial, genomes now provides the ability to dissect how genetic variation in mitochondrial genes alter cellular function across a variety of human tissue types. This review will examine the origins of mitochondrial heteroplasmic variation and propagation, and the tools used to model mitochondrial genetic diseases. Additionally, we discuss how iPSC technologies represent an opportunity to advance our understanding of human mitochondrial genetics in disease.
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Affiliation(s)
- Jesse D. Moreira
- Evans Department of Medicine and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA; (J.D.M.); (D.M.G.)
| | - Deepa M. Gopal
- Evans Department of Medicine and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA; (J.D.M.); (D.M.G.)
- Cardiovascular Medicine Section, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Darrell N. Kotton
- Boston Medical Center, Center for Regenerative Medicine of Boston University, Boston, MA 02118, USA;
- The Pulmonary Center, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Jessica L. Fetterman
- Evans Department of Medicine and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA; (J.D.M.); (D.M.G.)
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34
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Sarfallah A, Zamudio-Ochoa A, Anikin M, Temiakov D. Mechanism of transcription initiation and primer generation at the mitochondrial replication origin OriL. EMBO J 2021; 40:e107988. [PMID: 34423452 DOI: 10.15252/embj.2021107988] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 07/19/2021] [Accepted: 07/27/2021] [Indexed: 11/09/2022] Open
Abstract
The intricate process of human mtDNA replication requires the coordinated action of both transcription and replication machineries. Transcription and replication events at the lagging strand of mtDNA prompt the formation of a stem-loop structure (OriL) and the synthesis of a ∼25 nt RNA primer by mitochondrial RNA polymerase (mtRNAP). The mechanisms by which mtRNAP recognizes OriL, initiates transcription, and transfers the primer to the replisome are poorly understood. We found that transcription initiation at OriL involves slippage of the nascent transcript. The transcript slippage is essential for initiation complex stability and its ability to translocate the mitochondrial DNA polymerase gamma, PolG, which pre-binds to OriL, downstream of the replication origin thus allowing for the primer synthesis. Our data suggest the primosome assembly at OriL-a complex of mtRNAP and PolG-can efficiently generate the primer, transfer it to the replisome, and protect it from degradation by mitochondrial endonucleases.
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Affiliation(s)
- Azadeh Sarfallah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Angelica Zamudio-Ochoa
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael Anikin
- Department of Cell Biology and Neuroscience, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
| | - Dmitry Temiakov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
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35
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Meunier I, Bocquet B, Defoort-Dhellemmes S, Smirnov V, Arndt C, Picot MC, Dollfus H, Charif M, Audo I, Huguet H, Zanlonghi X, Lenaers G. Characterization of SSBP1-related optic atrophy and foveopathy. Sci Rep 2021; 11:18703. [PMID: 34548540 PMCID: PMC8455542 DOI: 10.1038/s41598-021-98150-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 09/03/2021] [Indexed: 11/17/2022] Open
Abstract
Dominant optic atrophy (DOA) is genetically heterogeneous and most commonly caused by mutations in OPA1. To distinguish between the classical OPA1-related and the recently identified SSBP1-related DOAs, the retina and fovea of 27 patients carrying the SSBP1 p.Arg38Gln variant were scrutinized using 20° × 20° macular cube and 30° and 55° field fundus autofluorescence photographs. Age of onset, visual acuity, retinal nerve fiber layer and macular thicknesses were recorded. Three SSBP1-patients were asymptomatic, 10 had isolated DOA, and 12 had a combined DOA plus foveopathy. The foveopathy, with a tiny defect of the ellipsoid and interdigitation lines, was similar in all patients, independent of age. There were no significant statistical differences in terms of visual acuity and SD-OCT measurements between patients with isolated DOA (mean visual acuity in decimals: 0.54 ± 0.41) and those with combined foveopathy (0.50 ± 0.23). Two patients over 50 years of age developed a progressive rod-cone dystrophy, leading to severe visual impairment. SSBP1-related DOA shares similarities with OPA1-related DOA with an incomplete penetrance and an early childhood visual impairment. Nevertheless, the presence of a congenital foveopathy with no impact on visual acuity is a major criterion to distinguish SSBP1 cases and orient the appropriate genetic analysis.
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Affiliation(s)
- Isabelle Meunier
- National reference centre for inherited sensory diseases, University Hospital of Montpellier, University of Montpellier, Montpellier, France. .,Sensgene Care Network, Strasbourg, France. .,Institute for Neurosciences of Montpellier, Inserm, University of Montpellier, Montpellier, France.
| | - Béatrice Bocquet
- National reference centre for inherited sensory diseases, University Hospital of Montpellier, University of Montpellier, Montpellier, France.,Sensgene Care Network, Strasbourg, France.,Institute for Neurosciences of Montpellier, Inserm, University of Montpellier, Montpellier, France
| | - Sabine Defoort-Dhellemmes
- Sensgene Care Network, Strasbourg, France.,Department of Neuro-Ophthalmology and Electrophysiology, Robert Salengro Hospital, Lille, France
| | - Vasily Smirnov
- Sensgene Care Network, Strasbourg, France.,Department of Neuro-Ophthalmology and Electrophysiology, Robert Salengro Hospital, Lille, France
| | - Carl Arndt
- Department of Ophthalmology, University Hospital of Reims, Reims, France
| | - Marie Christine Picot
- Clinical Investigation Center (CIC) and Clinical Research and Epidemiology Unit (URCE), Montpellier, France
| | - Hélène Dollfus
- Sensgene Care Network, Strasbourg, France.,Department of Ophthalmology, National Center for Rare Disorders in Ophthalmic Genetics CARGO, Strasbourg Hospital, Strasbourg, France
| | - Majida Charif
- Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Isabelle Audo
- Sensgene Care Network, Strasbourg, France.,CNRS, INSERM, Institut de la Vision, Sorbonne Université, Paris, France.,DHU Sight Restore, INSERM-DHOS CIC1423, CHNO des Quinze-Vingts, Paris, France
| | - Hélèna Huguet
- Clinical Investigation Center (CIC) and Clinical Research and Epidemiology Unit (URCE), Montpellier, France
| | - Xavier Zanlonghi
- Sensgene Care Network, Strasbourg, France.,Clinic Jules Verne, Nantes, France.,Department of Ophthalmology, University Hospital of Rennes, Rennes, France
| | - Guy Lenaers
- UMR CNRS 6015 - INSERM U1083, University of Angers MitoLab Team, University Hospital of Angers, Angers, France
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36
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Zhao L, Lavington E, Duffy S. Truly ubiquitous CRESS DNA viruses scattered across the eukaryotic tree of life. J Evol Biol 2021; 34:1901-1916. [PMID: 34498333 DOI: 10.1111/jeb.13927] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/05/2021] [Accepted: 08/18/2021] [Indexed: 11/29/2022]
Abstract
Until recently, most viruses detected and characterized were of economic significance, associated with agricultural and medical diseases. This was certainly true for the eukaryote-infecting circular Rep (replication-associated protein)-encoding single-stranded DNA (CRESS DNA) viruses, which were thought to be a relatively small group of viruses. With the explosion of metagenomic sequencing over the past decade and increasing use of rolling-circle replication for sequence amplification, scientists have identified and annotated copious numbers of novel CRESS DNA viruses - many without known hosts but which have been found in association with eukaryotes. Similar advances in cellular genomics have revealed that many eukaryotes have endogenous sequences homologous to viral Reps, which not only provide 'fossil records' to reconstruct the evolutionary history of CRESS DNA viruses but also reveal potential host species for viruses known by their sequences alone. The Rep protein is a conserved protein that all CRESS DNA viruses use to assist rolling-circle replication that is known to be endogenized in a few eukaryotic species (notably tobacco and water yam). A systematic search for endogenous Rep-like sequences in GenBank's non-redundant eukaryotic database was performed using tBLASTn. We utilized relaxed search criteria for the capture of integrated Rep sequence within eukaryotic genomes, identifying 93 unique species with an endogenized fragment of Rep in their nuclear, plasmid (one species), mitochondrial (six species) or chloroplast (eight species) genomes. These species come from 19 different phyla, scattered across the eukaryotic tree of life. Exogenous and endogenous CRESS DNA viral Rep tree topology suggested potential hosts for one family of uncharacterized viruses and supports a primarily fungal host range for genomoviruses.
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Affiliation(s)
- Lele Zhao
- Department of Ecology, Evolution and Natural Resources, School of Environmental and Biological Sciences, Rutgers, the State University of New Jersey, New Brunswick, New Jersey, USA.,Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Erik Lavington
- Department of Ecology, Evolution and Natural Resources, School of Environmental and Biological Sciences, Rutgers, the State University of New Jersey, New Brunswick, New Jersey, USA
| | - Siobain Duffy
- Department of Ecology, Evolution and Natural Resources, School of Environmental and Biological Sciences, Rutgers, the State University of New Jersey, New Brunswick, New Jersey, USA
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37
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Jiang M, Xie X, Zhu X, Jiang S, Milenkovic D, Misic J, Shi Y, Tandukar N, Li X, Atanassov I, Jenninger L, Hoberg E, Albarran-Gutierrez S, Szilagyi Z, Macao B, Siira SJ, Carelli V, Griffith JD, Gustafsson CM, Nicholls TJ, Filipovska A, Larsson NG, Falkenberg M. The mitochondrial single-stranded DNA binding protein is essential for initiation of mtDNA replication. SCIENCE ADVANCES 2021; 7:eabf8631. [PMID: 34215584 PMCID: PMC11057760 DOI: 10.1126/sciadv.abf8631] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 05/20/2021] [Indexed: 06/13/2023]
Abstract
We report a role for the mitochondrial single-stranded DNA binding protein (mtSSB) in regulating mitochondrial DNA (mtDNA) replication initiation in mammalian mitochondria. Transcription from the light-strand promoter (LSP) is required both for gene expression and for generating the RNA primers needed for initiation of mtDNA synthesis. In the absence of mtSSB, transcription from LSP is strongly up-regulated, but no replication primers are formed. Using deep sequencing in a mouse knockout model and biochemical reconstitution experiments with pure proteins, we find that mtSSB is necessary to restrict transcription initiation to optimize RNA primer formation at both origins of mtDNA replication. Last, we show that human pathological versions of mtSSB causing severe mitochondrial disease cannot efficiently support primer formation and initiation of mtDNA replication.
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Affiliation(s)
- Min Jiang
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Xie Xie
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Xuefeng Zhu
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Shan Jiang
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden
| | - Dusanka Milenkovic
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Jelena Misic
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden
| | - Yonghong Shi
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Nirwan Tandukar
- Lineberger Comprehensive Cancer Center, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27514, USA
| | - Xinping Li
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Ilian Atanassov
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Louise Jenninger
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Emily Hoberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Sara Albarran-Gutierrez
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Zsolt Szilagyi
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Bertil Macao
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Stefan J Siira
- Harry Perkins Institute of Medical Research and ARC Centre of Excellence in Synthetic Biology, Nedlands, WA 6009, Australia
- Telethon Kids Institute, Northern Entrance, Perth Children's Hospital, 15 Hospital Avenue, Nedlands, WA, Australia
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27514, USA
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Thomas J Nicholls
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research and ARC Centre of Excellence in Synthetic Biology, Nedlands, WA 6009, Australia
- Telethon Kids Institute, Northern Entrance, Perth Children's Hospital, 15 Hospital Avenue, Nedlands, WA, Australia
| | - Nils-Göran Larsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden.
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden.
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38
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Stimulation of Variant Forms of the Mitochondrial DNA Helicase Twinkle by the Mitochondrial Single-Stranded DNA-Binding Protein. Methods Mol Biol 2021. [PMID: 33847968 DOI: 10.1007/978-1-0716-1290-3_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Defects in mitochondrial DNA (mtDNA) maintenance may lead to disturbances in mitochondrial homeostasis and energy production in eukaryotic cells, causing diseases. During mtDNA replication, the mitochondrial single-stranded DNA-binding protein (mtSSB) stabilizes and protects the exposed single-stranded mtDNA from nucleolysis; perhaps more importantly, it appears to coordinate the actions of both the replicative mtDNA helicase Twinkle and DNA polymerase gamma at the replication fork. Here, we describe a helicase stimulation protocol to test in vitro the functional interaction between mtSSB and variant forms of Twinkle. We show for the first time that the C-terminal tail of Twinkle is important for such an interaction, and that it negatively regulates helicase unwinding activity in a salt-dependent manner.
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39
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Sebastian W, Sukumaran S, Gopalakrishnan A. The signals of selective constraints on the mitochondrial non-coding control region: insights from comparative mitogenomics of Clupeoid fishes. Genetica 2021; 149:191-201. [PMID: 33914198 DOI: 10.1007/s10709-021-00121-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/22/2021] [Indexed: 11/24/2022]
Abstract
The vertebrate mitochondrial genome is characterized by an exceptional organization evolving towards a reduced size. However, the persistence of a non-coding and highly variable control region is against this evolutionary trend that is explained by the presence of conserved sequence motifs or binding sites for nuclear-organized proteins that regulate mtDNA maintenance and expression. We performed a comparative mitogenomic investigation of the non-coding control region to understand its evolutionary patterns in Clupeoid fishes which are widely distributed across oceans of the world, exhibiting exemplary evolutionary potential. We confirmed the ability of sequence flanking the conserved sequence motifs in the control region to form stable secondary structures. The existence of evolutionarily conserved secondary structures without primary structure conservation suggested the action of selective constraints towards maintaining the secondary structure. The functional secondary structure is maintained by retaining the frequency of discontinuous AT and TG repeats along with compensatory base substitutions in the stem forming regions which can be considered as a selective constraint. The nucleotide polymorphism along the flanking regions of conserved sequence motifs can be explained as errors during the enzymatic replication of secondary structure-forming repeat elements. The evidence for selective constraints on secondary structures emphasizes the role of the control region in mitogenome function. Maintenance of high frequency of discontinuous repeats can be proposed as a model of adaptive evolution against the mutations that break the secondary structure involved in the efficient regulation of mtDNA functions substantiating the efficient functioning of the control region even in a high nucleotide polymorphism environment.
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Affiliation(s)
- Wilson Sebastian
- ICAR-Central Marine Fisheries Research Institute, Ernakulam North P.O, Kochi, 682018, Kerala, India
| | - Sandhya Sukumaran
- ICAR-Central Marine Fisheries Research Institute, Ernakulam North P.O, Kochi, 682018, Kerala, India.
| | - A Gopalakrishnan
- ICAR-Central Marine Fisheries Research Institute, Ernakulam North P.O, Kochi, 682018, Kerala, India
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40
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Sullivan ED, Longley MJ, Copeland WC. Polymerase γ efficiently replicates through many natural template barriers but stalls at the HSP1 quadruplex. J Biol Chem 2021; 295:17802-17815. [PMID: 33454015 DOI: 10.1074/jbc.ra120.015390] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/05/2020] [Indexed: 12/27/2022] Open
Abstract
Faithful replication of the mitochondrial genome is carried out by a set of key nuclear-encoded proteins. DNA polymerase γ is a core component of the mtDNA replisome and the only replicative DNA polymerase localized to mitochondria. The asynchronous mechanism of mtDNA replication predicts that the replication machinery encounters dsDNA and unique physical barriers such as structured genes, G-quadruplexes, and other obstacles. In vitro experiments here provide evidence that the polymerase γ heterotrimer is well-adapted to efficiently synthesize DNA, despite the presence of many naturally occurring roadblocks. However, we identified a specific G-quadruplex-forming sequence at the heavy-strand promoter (HSP1) that has the potential to cause significant stalling of mtDNA replication. Furthermore, this structured region of DNA corresponds to the break site for a large (3,895 bp) deletion observed in mitochondrial disease patients. The presence of this deletion in humans correlates with UV exposure, and we have found that efficiency of polymerase γ DNA synthesis is reduced after this quadruplex is exposed to UV in vitro.
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Affiliation(s)
- Eric D Sullivan
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Matthew J Longley
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - William C Copeland
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina, USA.
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41
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Maresca A, Carelli V. Molecular Mechanisms behind Inherited Neurodegeneration of the Optic Nerve. Biomolecules 2021; 11:496. [PMID: 33806088 PMCID: PMC8064499 DOI: 10.3390/biom11040496] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 01/01/2023] Open
Abstract
Inherited neurodegeneration of the optic nerve is a paradigm in neurology, as many forms of isolated or syndromic optic atrophy are encountered in clinical practice. The retinal ganglion cells originate the axons that form the optic nerve. They are particularly vulnerable to mitochondrial dysfunction, as they present a peculiar cellular architecture, with axons that are not myelinated for a long intra-retinal segment, thus, very energy dependent. The genetic landscape of causative mutations and genes greatly enlarged in the last decade, pointing to common pathways. These mostly imply mitochondrial dysfunction, which leads to a similar outcome in terms of neurodegeneration. We here critically review these pathways, which include (1) complex I-related oxidative phosphorylation (OXPHOS) dysfunction, (2) mitochondrial dynamics, and (3) endoplasmic reticulum-mitochondrial inter-organellar crosstalk. These major pathogenic mechanisms are in turn interconnected and represent the target for therapeutic strategies. Thus, their deep understanding is the basis to set and test new effective therapies, an urgent unmet need for these patients. New tools are now available to capture all interlinked mechanistic intricacies for the pathogenesis of optic nerve neurodegeneration, casting hope for innovative therapies to be rapidly transferred into the clinic and effectively cure inherited optic neuropathies.
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Affiliation(s)
- Alessandra Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
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42
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Gustafson MA, Sullivan ED, Copeland WC. Consequences of compromised mitochondrial genome integrity. DNA Repair (Amst) 2021; 93:102916. [PMID: 33087282 DOI: 10.1016/j.dnarep.2020.102916] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Maintenance and replication of the mitochondrial genome (mtDNA) is essential to mitochondrial function and eukaryotic energy production through the electron transport chain. mtDNA is replicated by a core set of proteins: Pol γ, Twinkle, and the single-stranded DNA binding protein. Fewer pathways exist for repair of mtDNA than nuclear DNA, and unrepaired damage to mtDNA may accumulate and lead to dysfunctional mitochondria. The mitochondrial genome is susceptible to damage by both endogenous and exogenous sources. Missense mutations to the nuclear genes encoding the core mtDNA replisome (POLG, POLG2, TWNK, and SSBP1) cause changes to the biochemical functions of their protein products. These protein variants can damage mtDNA and perturb oxidative phosphorylation. Ultimately, these mutations cause a diverse set of diseases that can affect virtually every system in the body. Here, we briefly review the mechanisms of mtDNA damage and the clinical consequences of disease variants of the core mtDNA replisome.
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Affiliation(s)
- Margaret A Gustafson
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences (NIEHS), NIH, Research Triangle Park, NC, 27709, USA
| | - Eric D Sullivan
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences (NIEHS), NIH, Research Triangle Park, NC, 27709, USA
| | - William C Copeland
- Mitochondrial DNA Replication Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences (NIEHS), NIH, Research Triangle Park, NC, 27709, USA.
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43
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Lee Y, Kim T, Lee M, So S, Karagozlu MZ, Seo GH, Choi IH, Lee PCW, Kim CJ, Kang E, Lee BH. De Novo Development of mtDNA Deletion Due to Decreased POLG and SSBP1 Expression in Humans. Genes (Basel) 2021; 12:genes12020284. [PMID: 33671400 PMCID: PMC7922481 DOI: 10.3390/genes12020284] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/10/2021] [Accepted: 02/14/2021] [Indexed: 02/07/2023] Open
Abstract
Defects in the mitochondrial genome (mitochondrial DNA (mtDNA)) are associated with both congenital and acquired disorders in humans. Nuclear-encoded DNA polymerase subunit gamma (POLG) plays an important role in mtDNA replication, and proofreading and mutations in POLG have been linked with increased mtDNA deletions. SSBP1 is also a crucial gene for mtDNA replication. Here, we describe a patient diagnosed with Pearson syndrome with large mtDNA deletions that were not detected in the somatic cells of the mother. Exome sequencing was used to evaluate the nuclear factors associated with the patient and his family, which revealed a paternal POLG mutation (c.868C > T) and a maternal SSBP1 mutation (c.320G > A). The patient showed lower POLG and SSBP1 expression than his healthy brothers and the general population of a similar age. Notably, c.868C in the wild-type allele was highly methylated in the patient compared to the same site in both his healthy brothers. These results suggest that the co- deficient expression of POLG and SSBP1 genes could contribute to the development of mtDNA deletion.
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Affiliation(s)
- Yeonmi Lee
- Department of Convergence Medicine and Stem Cell Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.L.); (M.L.); (S.S.); (M.Z.K.)
| | - Taeho Kim
- Medical Genetics Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (T.K.); (G.H.S.); (I.H.C.)
| | - Miju Lee
- Department of Convergence Medicine and Stem Cell Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.L.); (M.L.); (S.S.); (M.Z.K.)
| | - Seongjun So
- Department of Convergence Medicine and Stem Cell Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.L.); (M.L.); (S.S.); (M.Z.K.)
| | - Mustafa Zafer Karagozlu
- Department of Convergence Medicine and Stem Cell Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.L.); (M.L.); (S.S.); (M.Z.K.)
| | - Go Hun Seo
- Medical Genetics Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (T.K.); (G.H.S.); (I.H.C.)
| | - In Hee Choi
- Medical Genetics Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (T.K.); (G.H.S.); (I.H.C.)
| | - Peter C. W. Lee
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea;
| | - Chong-Jai Kim
- Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea;
| | - Eunju Kang
- Department of Convergence Medicine and Stem Cell Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.L.); (M.L.); (S.S.); (M.Z.K.)
- Correspondence: (E.K.); (B.H.L.); Tel.: +82-2-3010-8547 (E.K.); +82-2-3010-5950 (B.H.L.)
| | - Beom Hee Lee
- Medical Genetics Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (T.K.); (G.H.S.); (I.H.C.)
- Correspondence: (E.K.); (B.H.L.); Tel.: +82-2-3010-8547 (E.K.); +82-2-3010-5950 (B.H.L.)
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44
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Cao Y, Xie L, Shi F, Tang M, Li Y, Hu J, Zhao L, Zhao L, Yu X, Luo X, Liao W, Bode AM. Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study. Signal Transduct Target Ther 2021; 6:15. [PMID: 33436584 PMCID: PMC7801793 DOI: 10.1038/s41392-020-00376-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/30/2020] [Accepted: 10/15/2020] [Indexed: 12/11/2022] Open
Abstract
Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.
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Affiliation(s)
- Ya Cao
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China. .,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China. .,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China. .,Research Center for Technologies of Nucleic Acid-Based Diagnostics and Therapeutics Hunan Province, 410078, Changsha, China. .,Molecular Imaging Research Center of Central South University, 410008, Changsha, Hunan, China. .,National Joint Engineering Research Center for Genetic Diagnostics of Infectious Diseases and Cancer, 410078, Changsha, China. .,Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.
| | - Longlong Xie
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China
| | - Feng Shi
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China
| | - Min Tang
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China.,Molecular Imaging Research Center of Central South University, 410008, Changsha, Hunan, China
| | - Yueshuo Li
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China
| | - Jianmin Hu
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China
| | - Lin Zhao
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China
| | - Luqing Zhao
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China
| | - Xinfang Yu
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China
| | - Xiangjian Luo
- Key Laboratory of Carcinogenesis and Invasion, Chinese Ministry of Education, Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China.,Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, 410078, Changsha, China.,Key Laboratory of Carcinogenesis, Chinese Ministry of Health, 410078, Changsha, China.,Molecular Imaging Research Center of Central South University, 410008, Changsha, Hunan, China
| | - Weihua Liao
- Department of Radiology, Xiangya Hospital, Central South University, 410078, Changsha, China
| | - Ann M Bode
- The Hormel Institute, University of Minnesota, Austin, MN, 55912, USA
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45
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Bermek O, Ciesielski GL. Analysis of Mitochondrial SSB-DNA Complexes and Their Effects on DNA Polymerase γ Activity by Electron Microscopy and Enzymatic Assays. Methods Mol Biol 2021; 2281:265-272. [PMID: 33847964 DOI: 10.1007/978-1-0716-1290-3_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The mitochondrial single-stranded DNA-binding protein (mtSSB) regulates the function of the mitochondrial DNA (mtDNA) replisome. In vitro, mtSSB stimulates the activity of enzymatic components of the replisome, namely mtDNA helicase and DNA polymerase gamma (Pol γ). We have demonstrated that the stimulatory properties of mtSSB result from its ability to organize the single-stranded DNA template in a specific manner. Here we present methods employing electron microscopy and enzymatic assays to characterize and classify the mtSSB-DNA complexes and their effects on the activity of Pol γ.
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Affiliation(s)
- Oya Bermek
- National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, USA
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46
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Filograna R, Mennuni M, Alsina D, Larsson NG. Mitochondrial DNA copy number in human disease: the more the better? FEBS Lett 2020; 595:976-1002. [PMID: 33314045 PMCID: PMC8247411 DOI: 10.1002/1873-3468.14021] [Citation(s) in RCA: 209] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/02/2020] [Accepted: 11/26/2020] [Indexed: 12/19/2022]
Abstract
Most of the genetic information has been lost or transferred to the nucleus during the evolution of mitochondria. Nevertheless, mitochondria have retained their own genome that is essential for oxidative phosphorylation (OXPHOS). In mammals, a gene‐dense circular mitochondrial DNA (mtDNA) of about 16.5 kb encodes 13 proteins, which constitute only 1% of the mitochondrial proteome. Mammalian mtDNA is present in thousands of copies per cell and mutations often affect only a fraction of them. Most pathogenic human mtDNA mutations are recessive and only cause OXPHOS defects if present above a certain critical threshold. However, emerging evidence strongly suggests that the proportion of mutated mtDNA copies is not the only determinant of disease but that also the absolute copy number matters. In this review, we critically discuss current knowledge of the role of mtDNA copy number regulation in various types of human diseases, including mitochondrial disorders, neurodegenerative disorders and cancer, and during ageing. We also provide an overview of new exciting therapeutic strategies to directly manipulate mtDNA to restore OXPHOS in mitochondrial diseases.
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Affiliation(s)
- Roberta Filograna
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Mara Mennuni
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - David Alsina
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Nils-Göran Larsson
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
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Mitochondrial Dysfunction in Parkinson's Disease: Focus on Mitochondrial DNA. Biomedicines 2020; 8:biomedicines8120591. [PMID: 33321831 PMCID: PMC7763033 DOI: 10.3390/biomedicines8120591] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/05/2020] [Accepted: 12/08/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondria, the energy stations of the cell, are the only extranuclear organelles, containing their own (mitochondrial) DNA (mtDNA) and the protein synthesizing machinery. The location of mtDNA in close proximity to the oxidative phosphorylation system of the inner mitochondrial membrane, the main source of reactive oxygen species (ROS), is an important factor responsible for its much higher mutation rate than nuclear DNA. Being more vulnerable to damage than nuclear DNA, mtDNA accumulates mutations, crucial for the development of mitochondrial dysfunction playing a key role in the pathogenesis of various diseases. Good evidence exists that some mtDNA mutations are associated with increased risk of Parkinson’s disease (PD), the movement disorder resulted from the degenerative loss of dopaminergic neurons of substantia nigra. Although their direct impact on mitochondrial function/dysfunction needs further investigation, results of various studies performed using cells isolated from PD patients or their mitochondria (cybrids) suggest their functional importance. Studies involving mtDNA mutator mice also demonstrated the importance of mtDNA deletions, which could also originate from abnormalities induced by mutations in nuclear encoded proteins needed for mtDNA replication (e.g., polymerase γ). However, proteomic studies revealed only a few mitochondrial proteins encoded by mtDNA which were downregulated in various PD models. This suggests nuclear suppression of the mitochondrial defects, which obviously involve cross-talk between nuclear and mitochondrial genomes for maintenance of mitochondrial functioning.
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Falkenberg M, Gustafsson CM. Mammalian mitochondrial DNA replication and mechanisms of deletion formation. Crit Rev Biochem Mol Biol 2020; 55:509-524. [DOI: 10.1080/10409238.2020.1818684] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Claes M. Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
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Jia H, Mo W, Hong M, Jiang S, Zhang YY, He D, Yu D, Shi Y, Cao J, Xu X, Zhang S. Interferon-α inducible protein 6 (IFI6) confers protection against ionizing radiation in skin cells. J Dermatol Sci 2020; 100:139-147. [PMID: 33059972 DOI: 10.1016/j.jdermsci.2020.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/03/2020] [Accepted: 09/13/2020] [Indexed: 01/08/2023]
Abstract
BACKGROUND Radiation-induced skin injury is one of the main adverse effects and a dose-limiting factor of radiotherapy without feasible treatment. The underlying mechanism of this disease is still limited. OBJECTIVE To investigate the potential molecular pathways and mechanisms of radiation-induced skin injury. METHODS mRNA expression profiles were determined by Affymetrix Human HTA2.0 microarray.IFI6 overexpression and knockdown were mediated by lentivirus. The functional changes of skin cells were measured by flow cytometry, ROS probe and Edu probe. Protein distribution was detected by immunofluorescence experiment, and IFI6-interacting proteins were detected by immunoprecipitation (IP) combined with mass spectrometry. The global gene changes in IFI6-overexpressed skin cells after irradiation were detected by RNA-seq. RESULTS mRNA expression profiling showed 50 upregulated and 13 down regulated genes and interferon alpha inducible protein 6 (IFI6) was top upregulated. Overexpression of IFI6 promoted cell proliferation and reduced cell apoptosis as well as ROS production following radiation, and conversely, increased the radiosensitivity of HaCaT and human skin fibroblast (WS1). IFI6 was translocated into nucleus in irradiated skin cells and the interacting relationship with mitochondrial single-stranded DNA-binding protein 1 (SSBP1), which could enhance the transcriptional activity of heat shock transcription factor 1 (HSF1).IFI6 augmented HSF1 activity following radiation in HaCaT and WS1 cells. RNA-seq analysis showed IFI6 modulated virus infection and cellular response to stress pathways, which may help to further explore how IFI6 regulate the transcriptional activity of HSF1. CONCLUSION This study reveals that IFI6 is induced by ionizing radiation and confers radioprotection in skin cells.
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Affiliation(s)
- Huimin Jia
- State Key Lab of Radiation Medicine and Protection, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China
| | - Wei Mo
- State Key Lab of Radiation Medicine and Protection, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China
| | - Min Hong
- State Key Lab of Radiation Medicine and Protection, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China
| | - Sheng Jiang
- Second Affiliated Hospital of Chengdu Medical College, China National Nuclear Corporation 416 Hospital, Chengdu, China
| | - Yuan-Yuan Zhang
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China
| | - Dan He
- Second Affiliated Hospital of Chengdu Medical College, China National Nuclear Corporation 416 Hospital, Chengdu, China
| | - Daojiang Yu
- Second Affiliated Hospital of Chengdu Medical College, China National Nuclear Corporation 416 Hospital, Chengdu, China
| | - Yuhong Shi
- Second Affiliated Hospital of Chengdu Medical College, China National Nuclear Corporation 416 Hospital, Chengdu, China
| | - Jianping Cao
- State Key Lab of Radiation Medicine and Protection, Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China
| | - Xiaohui Xu
- Department of General Surgery, The First People's Hospital of Taicang, Taicang Affiliated Hospital of Soochow University, Taicang, China.
| | - Shuyu Zhang
- Second Affiliated Hospital of Chengdu Medical College, China National Nuclear Corporation 416 Hospital, Chengdu, China; West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, China.
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Cho CH, Park SI, Ciniglia C, Yang EC, Graf L, Bhattacharya D, Yoon HS. Potential causes and consequences of rapid mitochondrial genome evolution in thermoacidophilic Galdieria (Rhodophyta). BMC Evol Biol 2020; 20:112. [PMID: 32892741 PMCID: PMC7487498 DOI: 10.1186/s12862-020-01677-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/20/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The Cyanidiophyceae is an early-diverged red algal class that thrives in extreme conditions around acidic hot springs. Although this lineage has been highlighted as a model for understanding the biology of extremophilic eukaryotes, little is known about the molecular evolution of their mitochondrial genomes (mitogenomes). RESULTS To fill this knowledge gap, we sequenced five mitogenomes from representative clades of Cyanidiophyceae and identified two major groups, here referred to as Galdieria-type (G-type) and Cyanidium-type (C-type). G-type mitogenomes exhibit the following three features: (i) reduction in genome size and gene inventory, (ii) evolution of unique protein properties including charge, hydropathy, stability, amino acid composition, and protein size, and (iii) distinctive GC-content and skewness of nucleotides. Based on GC-skew-associated characteristics, we postulate that unidirectional DNA replication may have resulted in the rapid evolution of G-type mitogenomes. CONCLUSIONS The high divergence of G-type mitogenomes was likely driven by natural selection in the multiple extreme environments that Galdieria species inhabit combined with their highly flexible heterotrophic metabolism. We speculate that the interplay between mitogenome divergence and adaptation may help explain the dominance of Galdieria species in diverse extreme habitats.
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Affiliation(s)
- Chung Hyun Cho
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Seung In Park
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Claudia Ciniglia
- Department of Environmental, Biological and Pharmaceutical Science and Technologies, University of Campania Luigi Vanvitelli, 81100, Caserta, Italy
| | - Eun Chan Yang
- Marine Ecosystem Research Center, Korea Institute of Ocean Science and Technology, Busan, 49111, South Korea
| | - Louis Graf
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea
| | - Debashish Bhattacharya
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, 08901, USA
| | - Hwan Su Yoon
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, South Korea.
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