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Alexeyev M, Bai Y. An alternative model for maternal mtDNA inheritance. Nat Genet 2025; 57:1103-1104. [PMID: 40113902 DOI: 10.1038/s41588-025-02149-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 02/27/2025] [Indexed: 03/22/2025]
Affiliation(s)
- Mikhail Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, AL, USA.
| | - Yidong Bai
- Department of Cell Systems and Anatomy, the University of Texas Health San Antonio, San Antonio, TX, USA
- Population Science and Prevention Program, Mays Cancer Center, the University of Texas Health San Antonio, San Antonio, TX, USA
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2
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Forslund JME, Nguyen TVH, Parkash V, Berner A, Goffart S, Pohjoismäki JLO, Wanrooij PH, Johansson E, Wanrooij S. The POLγ Y951N patient mutation disrupts the switch between DNA synthesis and proofreading, triggering mitochondrial DNA instability. Proc Natl Acad Sci U S A 2025; 122:e2417477122. [PMID: 40238457 PMCID: PMC12036981 DOI: 10.1073/pnas.2417477122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2024] [Accepted: 03/12/2025] [Indexed: 04/18/2025] Open
Abstract
Mitochondrial DNA (mtDNA) stability, essential for cellular energy production, relies on DNA polymerase gamma (POLγ). Here, we show that the POLγ Y951N disease-causing mutation induces replication stalling and severe mtDNA depletion. However, unlike other POLγ disease-causing mutations, Y951N does not directly impair exonuclease activity and only mildly affects polymerase activity. Instead, we found that Y951N compromises the enzyme's ability to efficiently toggle between DNA synthesis and degradation, and is thus a patient-derived mutation with impaired polymerase-exonuclease switching. These findings provide insights into the intramolecular switch when POLγ proofreads the newly synthesized DNA strand and reveal a new mechanism for causing mitochondrial DNA instability.
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Affiliation(s)
| | - Tran V. H. Nguyen
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå90187, Sweden
| | - Vimal Parkash
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå90187, Sweden
| | - Andreas Berner
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå90187, Sweden
| | - Steffi Goffart
- Department of Environmental and Biological Sciences, University of Eastern Finland, JoensuuFI-80101, Finland
| | - Jaakko L. O. Pohjoismäki
- Department of Environmental and Biological Sciences, University of Eastern Finland, JoensuuFI-80101, Finland
| | - Paulina H. Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå90187, Sweden
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå90187, Sweden
| | - Sjoerd Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå90187, Sweden
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3
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Greenwald E, Galls D, Park J, Jain N, Montgomery S, Roy B, Yin Y, Fire A. DragonRNA: Generality of DNA-primed RNA-extension activities by DNA-directed RNA polymerases. Nucleic Acids Res 2025; 53:gkaf236. [PMID: 40197829 PMCID: PMC11976148 DOI: 10.1093/nar/gkaf236] [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: 05/24/2024] [Revised: 02/25/2025] [Accepted: 03/14/2025] [Indexed: 04/10/2025] Open
Abstract
RNA polymerases (RNAPs) transcribe DNA into RNA. Several RNAPs, including from bacteriophages Sp6 and T7, Escherichia coli, and wheat germ, had been shown to add ribonucleotides to DNA 3' ends. Mitochondria have their own RNAPs (mtRNAPs). Examining reaction products of RNAPs acting on DNA molecules with free 3' ends, we found yeast and human mtRNAP preparations exhibit a robust activity of extending DNA 3' ends with ribonucleotides. The resulting molecules are serial DNA→RNA chains with the input DNA on the 5' end and extended RNA on the 3' end. Such chains were produced from a wide variety of DNA oligonucleotide inputs with short complementarity in the sequence to the DNA 3' end with the sequence of the RNA portion complementary to the input DNA. We provide a set of fluorescence-based assays for facile detection of such products and show that this activity is a general property of diverse RNAPs, including phage RNAPs and multi-subunit E. coli RNAP. These results support a model in which DNA serves as both primer and template, with extension beginning when the 3' end of the DNA is elongated with a ribonucleotide. As this DNA→RNA class of molecule remains unnamed, we propose the name DragonRNA.
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Affiliation(s)
- Emily Greenwald
- Department of Genetics, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
- Department of Pathology, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
| | - Drew Galls
- Department of Genetics, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
- Department of Pathology, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
| | - Joon Park
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, 301 University Blvd, Galveston, TX 77555, United States
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, 301 University Blvd, Galveston, TX 77555, United States
| | - Nimit Jain
- Department of Pathology, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
- Department of Bioengineering, Stanford University, 443 Via Ortega, Stanford, CA 94305, United States
| | - Stephen B Montgomery
- Department of Genetics, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
- Department of Pathology, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
- Department of Biomedical Data Science, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
| | - Bijoyita Roy
- New England Biolabs, 240 County Road, Ipswich, MA 01938, United States
| | - Y Whitney Yin
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, 301 University Blvd, Galveston, TX 77555, United States
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch at Galveston, 301 University Blvd, Galveston, TX 77555, United States
| | - Andrew Z Fire
- Department of Genetics, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
- Department of Pathology, Stanford University, 1291 Welch Road, Stanford, CA 94305, United States
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4
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Lin YR, Li JK, Yang X, Dong BR, Liu RA, Wang XM, Yu M, Xiong W. Mitochondrial single-stranded DNA binding protein 1 (SSBP1) high expression as a potential biomarker and association with poor prognosis in hepatocellular carcinoma (HCC). Transl Cancer Res 2025; 14:112-128. [PMID: 39974423 PMCID: PMC11833372 DOI: 10.21037/tcr-24-1196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2024] [Accepted: 12/04/2024] [Indexed: 02/21/2025]
Abstract
Background Single-stranded DNA binding protein 1 (SSBP1) is a DNA binding protein found in mitochondria, encoded by nuclear genes. SSBP1 plays a crucial role in responding to mitochondrial DNA (mtDNA) damage and maintaining genome stability, and it is linked to cancer occurrence and progression, but its role in hepatocellular carcinoma (HCC) is still unclear. Therefore, the aim of this research was to investigate the expression of SSBP1 and its potential clinical significance in HCC. Methods RNA-seq data and clinical information of HCC samples and normal liver samples were downloaded from The Cancer Genome Atlas (TCGA). The expression of SSBP1 in HCC and its correlation with clinical pathological indicators, prognosis, immune cells, and infiltration were analyzed using R software, while the diagnostic value of SSBP1 in HCC was evaluated. Using the R software, we conducted Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and gene set enrichment analysis (GSEA) on the SSBP1 expression in HCC. Immunohistochemistry (IHC) detected SSBP1 expression in 31 HCC tissue pairs. Western blotting and quantitative reverse transcription polymerase chain reaction (qRT-PCR) quantified protein and mRNA levels in 6 fresh HCC tissue. Protein expression and distribution of SSBP1 in HCC cell lines were analyzed using qRT-PCR, Western blotting, and Immunofluorescence techniques. Results SSBP1 mRNA expression was significantly higher in HCC tissues compared to normal tissues (P<0.001) in both matched and unmatched samples. SSBP1 expression was correlated with gender and M stage (P<0.05), but not with other factors. High SSBP1 expression was identified as an independent risk factor for overall survival (OS) in HCC patients [hazard ratio =1.713, P=0.01]. Immunocell infiltration analysis showed a negative correlation between SSBP1 expression and level of naive B cells, but a positive correlation with memory B cells and macrophages (|Spearman's r| >0.2, P<0.05). The diagnostic value of SSBP1 mRNA expression for early diagnosis prognosis of HCC (area under the curve >0.50). The GO enrichment analysis of SSBP1 revealed that it was enriched for mitochondrial biological functions. KEGG analysis showed that SSBP1 was associated with multiple DNA replication, mismatch repair and homologous recombination pathways. GSEA analysis showed that the first three pathways strongly related to the high expression of SSBP1 were DNA repair, myc-targets-v1 and reactive oxygen species signaling pathways. Validation through IHC and Western blotting high SSBP1 protein expression in HCC tissue, as well as qRT-PCR and Western blotting results showed high expression in HCC cell lines. Immunofluorescence experiments indicated the localization of SSBP1 in the mitochondria of HCC cells. Conclusions High expression of SSBP1 is an independent risk factor for poor prognosis in HCC patients and has good diagnostic value.
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Affiliation(s)
- Ya-Ru Lin
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dali University, Dali, China
- Yunnan Provincial Key Laboratory of Clinical Biochemical Testing, College of Basic Medical Sciences, Dali University, Dali, China
- Yunnan Provincial Key Laboratory of Entomological Biopharmaceutical R&D, College of Pharmacy, Dali University, Dali, China
| | - Jian-Kang Li
- Laboratory of Biochemistry and Molecular Biology, College of Life Sciences, Yunnan University, Kunming, China
| | - Xi Yang
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dali University, Dali, China
- Yunnan Provincial Key Laboratory of Clinical Biochemical Testing, College of Basic Medical Sciences, Dali University, Dali, China
| | - Bao-Ru Dong
- Department of General Surgery, The Second People’s Hospital of Baoshan, Baoshan, China
| | - Ru-Ai Liu
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dali University, Dali, China
- Yunnan Provincial Key Laboratory of Clinical Biochemical Testing, College of Basic Medical Sciences, Dali University, Dali, China
| | - Xin-Meng Wang
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dali University, Dali, China
- Yunnan Provincial Key Laboratory of Clinical Biochemical Testing, College of Basic Medical Sciences, Dali University, Dali, China
| | - Min Yu
- Laboratory of Biochemistry and Molecular Biology, College of Life Sciences, Yunnan University, Kunming, China
| | - Wei Xiong
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dali University, Dali, China
- Yunnan Provincial Key Laboratory of Clinical Biochemical Testing, College of Basic Medical Sciences, Dali University, Dali, China
- Yunnan Provincial Key Laboratory of Entomological Biopharmaceutical R&D, College of Pharmacy, Dali University, Dali, China
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5
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Tapanainen R, Aasumets K, Fekete Z, Goffart S, Dufour E, L O Pohjoismäki J. Species-specific variation in mitochondrial genome tandem repeat polymorphisms in hares (Lepus spp., Lagomorpha, Leporidae) provides insight into their evolution. Gene 2024; 926:148644. [PMID: 38851366 DOI: 10.1016/j.gene.2024.148644] [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: 03/09/2024] [Revised: 04/23/2024] [Accepted: 06/03/2024] [Indexed: 06/10/2024]
Abstract
The non-coding regions of the mitochondrial DNAs (mtDNAs) of hares, rabbits, and pikas (Lagomorpha) contain short (∼20 bp) and long (130-160 bp) tandem repeats, absent in related mammalian orders. In the presented study, we provide in-depth analysis for mountain hare (Lepus timidus) and brown hare (L. europaeus) mtDNA non-coding regions, together with a species- and population-level analysis of tandem repeat variation. Mountain hare short tandem repeats (SRs) as well as other analyzed hare species consist of two conserved 10 bp motifs, with only brown hares exhibiting a single, more variable motif. Long tandem repeats (LRs) also differ in sequence and copy number between species. Mountain hares have four to seven LRs, median value five, while brown hares exhibit five to nine LRs, median value six. Interestingly, introgressed mountain hare mtDNA in brown hares obtained an intermediate LR length distribution, with median copy number being the same as with conspecific brown hare mtDNA. In contrast, transfer of brown hare mtDNA into cultured mtDNA-less mountain hare cells maintained the original LR number, whereas the reciprocal transfer caused copy number instability, suggesting that cellular environment rather than the nuclear genomic background plays a role in the LR maintenance. Due to their dynamic nature and separation from other known conserved sequence elements on the non-coding region of hare mitochondrial genomes, the tandem repeat elements likely to represent signatures of ancient genetic rearrangements. clarifying the nature and dynamics of these rearrangements may shed light on the possible role of NCR repeated elements in mitochondria and in species evolution.
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Affiliation(s)
- Riikka Tapanainen
- University of Eastern Finland, Department of Environmental and Biological Sciences, Joensuu, Finland
| | - Koit Aasumets
- University of Eastern Finland, Department of Environmental and Biological Sciences, Joensuu, Finland
| | - Zsófia Fekete
- University of Eastern Finland, Department of Environmental and Biological Sciences, Joensuu, Finland; Hungarian University of Agriculture and Life Sciences, Institute of Genetics and Biotechnology, Gödöllő, Hungary
| | - Steffi Goffart
- University of Eastern Finland, Department of Environmental and Biological Sciences, Joensuu, Finland
| | - Eric Dufour
- Mitochondrial Bioenergetics and Metabolism, Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland
| | - Jaakko L O Pohjoismäki
- University of Eastern Finland, Department of Environmental and Biological Sciences, Joensuu, Finland.
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6
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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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7
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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] [Download PDF] [Figures] [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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8
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Humayun A, Lin LYT, Li HH, Fornace AJ. FAILLA MEMORIAL LECTURE How We Got Here: One Laboratory's Odyssey in the Field of Radiation-Inducible Genes. Radiat Res 2024; 201:617-627. [PMID: 38573158 DOI: 10.1667/rade-23-00205.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 03/11/2024] [Indexed: 04/05/2024]
Abstract
This review focuses on early discoveries that contributed to our understanding and the scope of transcriptional responses after radiation damage. Before the development of modern approaches to assess overall global transcriptomic responses, the idea that mammalian cells could respond to DNA-damaging agents in a manner analogous to bacteria was not generally accepted. To investigate this possibility, the development of technology to identify differentially expressed low-abundance transcripts substantially facilitated our appreciation that DNA damaging agents like UV radiation and subsequently ionizing radiation did in fact produce robust transcriptional responses. Here we focus on our identification and characterization of radiation-inducible genes, and how even early studies on stress gene signaling highlighted the broad scope of transcriptional responses to radiation damage. Since then, the central role of transcriptional responses to radiation injury in maintaining genome integrity has been highlighted in many processes, including cell cycle checkpoint control, resistance to cancer by p53 and other key factors, cell senescence, and metabolism.
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Affiliation(s)
- Arslon Humayun
- Department of Oncology, Lombardi Comprehensive Cancer Center, Washington, DC
| | | | - Heng-Hong Li
- Department of Oncology, Lombardi Comprehensive Cancer Center, Washington, DC
| | - Albert J Fornace
- Department of Oncology, Lombardi Comprehensive Cancer Center, Washington, DC
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, Washington, DC
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9
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Jiang S, Yuan T, Rosenberger FA, Mourier A, Dragano NRV, Kremer LS, Rubalcava-Gracia D, Hansen FM, Borg M, Mennuni M, Filograna R, Alsina D, Misic J, Koolmeister C, Papadea P, de Angelis MH, Ren L, Andersson O, Unger A, Bergbrede T, Di Lucrezia R, Wibom R, Zierath JR, Krook A, Giavalisco P, Mann M, Larsson NG. Inhibition of mammalian mtDNA transcription acts paradoxically to reverse diet-induced hepatosteatosis and obesity. Nat Metab 2024; 6:1024-1035. [PMID: 38689023 PMCID: PMC11199148 DOI: 10.1038/s42255-024-01038-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 03/28/2024] [Indexed: 05/02/2024]
Abstract
The oxidative phosphorylation system1 in mammalian mitochondria plays a key role in transducing energy from ingested nutrients2. Mitochondrial metabolism is dynamic and can be reprogrammed to support both catabolic and anabolic reactions, depending on physiological demands or disease states. Rewiring of mitochondrial metabolism is intricately linked to metabolic diseases and promotes tumour growth3-5. Here, we demonstrate that oral treatment with an inhibitor of mitochondrial transcription (IMT)6 shifts whole-animal metabolism towards fatty acid oxidation, which, in turn, leads to rapid normalization of body weight, reversal of hepatosteatosis and restoration of normal glucose tolerance in male mice on a high-fat diet. Paradoxically, the IMT treatment causes a severe reduction of oxidative phosphorylation capacity concomitant with marked upregulation of fatty acid oxidation in the liver, as determined by proteomics and metabolomics analyses. The IMT treatment leads to a marked reduction of complex I, the main dehydrogenase feeding electrons into the ubiquinone (Q) pool, whereas the levels of electron transfer flavoprotein dehydrogenase and other dehydrogenases connected to the Q pool are increased. This rewiring of metabolism caused by reduced mtDNA expression in the liver provides a principle for drug treatment of obesity and obesity-related pathology.
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Affiliation(s)
- Shan Jiang
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Taolin Yuan
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Florian A Rosenberger
- Department of Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Arnaud Mourier
- University of Bordeaux, CNRS, Institut de Biochimie et Génétique Cellulaires (IGBC) UMR, Bordeaux, France
| | - Nathalia R V Dragano
- Institute of Experimental Genetics - German Mouse Clinic, Helmholtz Zentrum, Munich, Germany
- German Center for Diabetes Research (DZD), Oberschleißheim-Neuherberg, Neuherberg, Germany
| | - Laura S Kremer
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Diana Rubalcava-Gracia
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Fynn M Hansen
- Department of Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Melissa Borg
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Mara Mennuni
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Roberta Filograna
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - David Alsina
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Jelena Misic
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Camilla Koolmeister
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Polyxeni Papadea
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Martin Hrabe de Angelis
- Institute of Experimental Genetics - German Mouse Clinic, Helmholtz Zentrum, Munich, Germany
- German Center for Diabetes Research (DZD), Oberschleißheim-Neuherberg, Neuherberg, Germany
- Chair of Experimental Genetics, TUM School of Life Sciences, Technische Universität München, Freising, Germany
| | - Lipeng Ren
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Olov Andersson
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Anke Unger
- Lead Discovery Center, Dortmund, Germany
| | | | | | - Rolf Wibom
- Centre for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Juleen R Zierath
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Anna Krook
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Patrick Giavalisco
- Metabolomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Nils-Göran Larsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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10
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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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11
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Zhang W, Yang Z, Wang W, Sun Q. Primase promotes the competition between transcription and replication on the same template strand resulting in DNA damage. Nat Commun 2024; 15:73. [PMID: 38168108 PMCID: PMC10761990 DOI: 10.1038/s41467-023-44443-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024] Open
Abstract
Transcription-replication conflicts (TRCs), especially Head-On TRCs (HO-TRCs) can introduce R-loops and DNA damage, however, the underlying mechanisms are still largely unclear. We previously identified a chloroplast-localized RNase H1 protein AtRNH1C that can remove R-loops and relax HO-TRCs for genome integrity. Through the mutagenesis screen, we identify a mutation in chloroplast-localized primase ATH that weakens the binding affinity of DNA template and reduces the activities of RNA primer synthesis and delivery. This slows down DNA replication, and reduces competition of transcription-replication, thus rescuing the developmental defects of atrnh1c. Strand-specific DNA damage sequencing reveals that HO-TRCs cause DNA damage at the end of the transcription unit in the lagging strand and overexpression of ATH can boost HO-TRCs and exacerbates DNA damage. Furthermore, mutation of plastid DNA polymerase Pol1A can similarly rescue the defects in atrnh1c mutants. Taken together these results illustrate a potentially conserved mechanism among organisms, of which the primase activity can promote the occurrence of transcription-replication conflicts leading to HO-TRCs and genome instability.
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Affiliation(s)
- Weifeng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, 100084, Beijing, China
- Tsinghua-Peking Center for Life Sciences, 100084, Beijing, China
| | - Zhuo Yang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, 100084, Beijing, China
- Tsinghua-Peking Center for Life Sciences, 100084, Beijing, China
| | - Wenjie Wang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, 100084, Beijing, China
- Tsinghua-Peking Center for Life Sciences, 100084, Beijing, China
| | - Qianwen Sun
- Center for Plant Biology, School of Life Sciences, Tsinghua University, 100084, Beijing, China.
- Tsinghua-Peking Center for Life Sciences, 100084, Beijing, China.
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12
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Alexeyev M. TFAM in mtDNA Homeostasis: Open Questions. DNA 2023; 3:134-136. [PMID: 37771599 PMCID: PMC10538575 DOI: 10.3390/dna3030011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Transcription factor A, mitochondrial (TFAM) is a key player in mitochondrial DNA (mtDNA) transcription and replication [...]
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Affiliation(s)
- Mikhail Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, AL 36688, USA
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13
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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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14
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Kozhukhar N, Alexeyev MF. 35 Years of TFAM Research: Old Protein, New Puzzles. BIOLOGY 2023; 12:823. [PMID: 37372108 DOI: 10.3390/biology12060823] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 05/29/2023] [Accepted: 06/03/2023] [Indexed: 06/29/2023]
Abstract
Transcription Factor A Mitochondrial (TFAM), through its contributions to mtDNA maintenance and expression, is essential for cellular bioenergetics and, therefore, for the very survival of cells. Thirty-five years of research on TFAM structure and function generated a considerable body of experimental evidence, some of which remains to be fully reconciled. Recent advancements allowed an unprecedented glimpse into the structure of TFAM complexed with promoter DNA and TFAM within the open promoter complexes. These novel insights, however, raise new questions about the function of this remarkable protein. In our review, we compile the available literature on TFAM structure and function and provide some critical analysis of the available data.
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Affiliation(s)
- Natalya Kozhukhar
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, AL 36688, USA
| | - Mikhail F Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, Mobile, AL 36688, USA
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15
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Chang YH, Kang EYC, Liu L, Jenny LA, Khang R, Seo GH, Lee H, Chen KJ, Wu WC, Hsiao MC, Wang NK. Maternal mosaicism in SSBP1 causing optic atrophy with retinal degeneration: implications for genetic counseling. Orphanet J Rare Dis 2023; 18:131. [PMID: 37259171 PMCID: PMC10233871 DOI: 10.1186/s13023-023-02748-9] [Citation(s) in RCA: 2] [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: 02/07/2023] [Accepted: 05/18/2023] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND Optic atrophy-13 with retinal and foveal abnormalities (OPA13) (MIM #165510) is a mitochondrial disease in which apparent bilateral optic atrophy is present and sometimes followed by retinal pigmentary changes or photoreceptors degeneration. OPA13 is caused by heterozygous mutation in the SSBP1 gene, associated with variable mitochondrial dysfunctions. RESULTS We have previously reported a 16-year-old Taiwanese male diagnosed with OPA13 and SSBP1 variant c.320G>A (p.Arg107Gln) was identified by whole exon sequence (WES). This variant was assumed to be de novo since his parents were clinically unaffected. However, WES and Sanger sequencing further revealed the proband's unaffected mother carrying the same SSBP1 variant with a 13% variant allele frequency (VAF) in her peripheral blood. That finding strongly indicates the maternal gonosomal mosaicism contributing to OPA13, which has not been reported before. CONCLUSIONS In summary, we described the first case of OPA13 caused by maternal gonosomal mosaicism in SSBP1. Parental mosaicism could be a serious issue in OPA13 diagnosis, and appropriate genetic counseling should be considered.
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Affiliation(s)
- Yin-Hsi Chang
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Eugene Yu-Chuan Kang
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Laura Liu
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Laura A Jenny
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, 635 West 165th Street, New York, NY, 10032, USA
| | - Rin Khang
- Division of Medical Genetics, 3Billion Inc., Seoul, South Korea
| | - Go Hun Seo
- Division of Medical Genetics, 3Billion Inc., Seoul, South Korea
| | - Hane Lee
- Division of Medical Genetics, 3Billion Inc., Seoul, South Korea
| | - Kuan-Jen Chen
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Wei-Chi Wu
- Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
- College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Meng-Chang Hsiao
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY, USA
| | - Nan-Kai Wang
- Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University Irving Medical Center, Columbia University, 635 West 165th Street, New York, NY, 10032, USA.
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16
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Chang YH, Kang EYC, Liu L, Jenny LA, Khang R, Seo GH, Lee H, Chen KJ, Wu WC, Hsiao MC, Wang NK. Maternal Mosaicism in SSBP1 Causing Optic Atrophy with Retinal Degeneration: Implications for Genetic Counseling. RESEARCH SQUARE 2023:rs.3.rs-2554402. [PMID: 36993412 PMCID: PMC10055506 DOI: 10.21203/rs.3.rs-2554402/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
Background: Optic atrophy-13 with retinal and foveal abnormalities (OPA13) (MIM #165510) is a mitochondrial disease in which apparent bilateral optic atrophy is present and sometimes followed by retinal pigmentary changes or photoreceptors degeneration. OPA13 is caused by heterozygous mutation in the SSBP1 gene, associated with variable mitochondrial dysfunctions. Results: We have previously reported a 16-year-old Taiwanese male diagnosed with OPA13 and SSBP1 variant c.320G>A (p.Arg107Gln) was identified by whole exon sequence (WES). This variant was assumed to be de novo since his parents were clinically unaffected. However, WES and Sanger sequencing further revealed the proband’s unaffected mother carrying the same SSBP1 variant with a 13% variant allele frequency (VAF) in her peripheral blood. That finding strongly indicates the maternal gonosomal mosaicism contributing to OPA13, which has not been reported before. Conclusions: In summary, we described the first case of OPA13 caused by maternal gonosomal mosaicism in SSBP1 . Parental mosaicism could be a serious issue in OPA13 diagnosis, and appropriate genetic counseling should be considered.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Meng-Chang Hsiao
- Columbia University Medical Center: Columbia University Irving Medical Center
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17
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Forslund JME, Stojkovič G, Wanrooij S. Rolling Circle Replication and Bypass of Damaged Nucleotides. Methods Mol Biol 2023; 2615:203-217. [PMID: 36807794 DOI: 10.1007/978-1-0716-2922-2_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Faithful mitochondrial DNA (mtDNA) replication is critical for the proper function of the oxidative phosphorylation system. Problems with mtDNA maintenance, such as replication stalling upon encountering DNA damage, impair this vital function and can potentially lead to disease. An in vitro reconstituted mtDNA replication system can be used to investigate how the mtDNA replisome deals with, for example, oxidatively or UV-damaged DNA. In this chapter, we provide a detailed protocol on how to study the bypass of different types of DNA damage using a rolling circle replication assay. The assay takes advantage of purified recombinant proteins and can be adapted to the examination of various aspects of mtDNA maintenance.
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Affiliation(s)
- Josefin M E Forslund
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Gorazd Stojkovič
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Sjoerd Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden.
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18
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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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19
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Structural insight and characterization of human Twinkle helicase in mitochondrial disease. Proc Natl Acad Sci U S A 2022; 119:e2207459119. [PMID: 35914129 PMCID: PMC9371709 DOI: 10.1073/pnas.2207459119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Twinkle is the mammalian helicase vital for replication and integrity of mitochondrial DNA. Over 90 Twinkle helicase disease variants have been linked to progressive external ophthalmoplegia and ataxia neuropathies among other mitochondrial diseases. Despite the biological and clinical importance, Twinkle represents the only remaining component of the human minimal mitochondrial replisome that has yet to be structurally characterized. Here, we present 3-dimensional structures of human Twinkle W315L. Employing cryo-electron microscopy (cryo-EM), we characterize the oligomeric assemblies of human full-length Twinkle W315L, define its multimeric interface, and map clinical variants associated with Twinkle in inherited mitochondrial disease. Cryo-EM, crosslinking-mass spectrometry, and molecular dynamics simulations provide insight into the dynamic movement and molecular consequences of the W315L clinical variant. Collectively, this ensemble of structures outlines a framework for studying Twinkle function in mitochondrial DNA replication and associated disease states.
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20
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Mehmedović M, Martucci M, Spåhr H, Ishak L, Mishra A, Sanchez-Sandoval ME, Pardo-Hernández C, Peter B, van den Wildenberg SM, Falkenberg M, Farge G. Disease causing mutation (P178L) in mitochondrial transcription factor A results in impaired mitochondrial transcription initiation. Biochim Biophys Acta Mol Basis Dis 2022; 1868:166467. [PMID: 35716868 DOI: 10.1016/j.bbadis.2022.166467] [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: 03/13/2022] [Revised: 05/31/2022] [Accepted: 06/09/2022] [Indexed: 10/18/2022]
Abstract
Mitochondrial transcription factor A (TFAM) is essential for the maintenance, expression, and packaging of mitochondrial DNA (mtDNA). Recently, a pathogenic homozygous variant in TFAM (P178L) has been associated with a severe mtDNA depletion syndrome leading to neonatal liver failure and early death. We have performed a biochemical characterization of the TFAM variant P178L in order to understand the molecular basis for the pathogenicity of this mutation. We observe no effects on DNA binding, and compaction of DNA is only mildly affected by the P178L amino acid change. Instead, the mutation severely impairs mtDNA transcription initiation at the mitochondrial heavy and light strand promoters. Molecular modeling suggests that the P178L mutation affects promoter sequence recognition and the interaction between TFAM and the tether helix of POLRMT, thus explaining transcription initiation deficiency.
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Affiliation(s)
- Majda Mehmedović
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Martial Martucci
- Université Clermont Auvergne, CNRS, Laboratoire de Physique de Clermont, F-63000 Clermont-Ferrand, France
| | - Henrik Spåhr
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden
| | - Layal Ishak
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Anup Mishra
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Maria Eugenia Sanchez-Sandoval
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Carlos Pardo-Hernández
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Siet M 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
| | - 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.
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21
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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: 18] [Impact Index Per Article: 6.0] [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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22
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Liu Y, Chen Z, Wang ZH, Delaney KM, Tang J, Pirooznia M, Lee DY, Tunc I, Li Y, Xu H. The PPR domain of mitochondrial RNA polymerase is an exoribonuclease required for mtDNA replication in Drosophila melanogaster. Nat Cell Biol 2022; 24:757-765. [PMID: 35449456 DOI: 10.1038/s41556-022-00887-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 03/08/2022] [Indexed: 11/09/2022]
Abstract
Mitochondrial DNA (mtDNA) replication and transcription are of paramount importance to cellular energy metabolism. Mitochondrial RNA polymerase is thought to be the primase for mtDNA replication. However, it is unclear how this enzyme, which normally transcribes long polycistronic RNAs, can produce short RNA oligonucleotides to initiate mtDNA replication. We show that the PPR domain of Drosophila mitochondrial RNA polymerase (PolrMT) has 3'-to-5' exoribonuclease activity, which is indispensable for PolrMT to synthesize short RNA oligonucleotides and prime DNA replication in vitro. An exoribonuclease-deficient mutant, PolrMTE423P, partially restores mitochondrial transcription but fails to support mtDNA replication when expressed in PolrMT-mutant flies, indicating that the exoribonuclease activity is necessary for mtDNA replication. In addition, overexpression of PolrMTE423P in adult flies leads to severe neuromuscular defects and a marked increase in mtDNA transcript errors, suggesting that exoribonuclease activity may contribute to the proofreading of mtDNA transcription.
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Affiliation(s)
- Yi Liu
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Zhe Chen
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Zong-Heng Wang
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Katherine M Delaney
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Juanjie Tang
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Mehdi Pirooznia
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Duck-Yeon Lee
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ilker Tunc
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yuesheng Li
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Hong Xu
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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23
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Arbeithuber B, Cremona MA, Hester J, Barrett A, Higgins B, Anthony K, Chiaromonte F, Diaz FJ, Makova KD. Advanced age increases frequencies of de novo mitochondrial mutations in macaque oocytes and somatic tissues. Proc Natl Acad Sci U S A 2022; 119:e2118740119. [PMID: 35394879 PMCID: PMC9169796 DOI: 10.1073/pnas.2118740119] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/25/2022] [Indexed: 12/18/2022] Open
Abstract
Mutations in mitochondrial DNA (mtDNA) contribute to multiple diseases. However, how new mtDNA mutations arise and accumulate with age remains understudied because of the high error rates of current sequencing technologies. Duplex sequencing reduces error rates by several orders of magnitude via independently tagging and analyzing each of the two template DNA strands. Here, using duplex sequencing, we obtained high-quality mtDNA sequences for somatic tissues (liver and skeletal muscle) and single oocytes of 30 unrelated rhesus macaques, from 1 to 23 y of age. Sequencing single oocytes minimized effects of natural selection on germline mutations. In total, we identified 17,637 tissue-specific de novo mutations. Their frequency increased ∼3.5-fold in liver and ∼2.8-fold in muscle over the ∼20 y assessed. Mutation frequency in oocytes increased ∼2.5-fold until the age of 9 y, but did not increase after that, suggesting that oocytes of older animals maintain the quality of their mtDNA. We found the light-strand origin of replication (OriL) to be a hotspot for mutation accumulation with aging in liver. Indeed, the 33-nucleotide-long OriL harbored 12 variant hotspots, 10 of which likely disrupt its hairpin structure and affect replication efficiency. Moreover, in somatic tissues, protein-coding variants were subject to positive selection (potentially mitigating toxic effects of mitochondrial activity), the strength of which increased with the number of macaques harboring variants. Our work illuminates the origins and accumulation of somatic and germline mtDNA mutations with aging in primates and has implications for delayed reproduction in modern human societies.
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Affiliation(s)
- Barbara Arbeithuber
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
- Experimental Gynaecology, Obstetrics and Gynaecological Endocrinology, Kepler University Hospital Linz, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Marzia A. Cremona
- Department of Operations and Decision Systems, Université Laval, Québec, QC G1V0A6, Canada
- Population Health and Optimal Health Practices, CHU de Québec - Université Laval Research Center, Québec, QC G1V4G2, Canada
- Center for Medical Genomics, The Pennsylvania State University, University Park, PA 16802
| | - James Hester
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
| | - Alison Barrett
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
| | - Bonnie Higgins
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
| | - Kate Anthony
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
| | - Francesca Chiaromonte
- Center for Medical Genomics, The Pennsylvania State University, University Park, PA 16802
- Department of Statistics, The Pennsylvania State University, University Park, PA 16802
- Institute of Economics and EMbeDS, Sant'Anna School of Advanced Studies, Pisa 56127, Italy
| | - Francisco J. Diaz
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
| | - Kateryna D. Makova
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
- Center for Medical Genomics, The Pennsylvania State University, University Park, PA 16802
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24
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Miranda M, Bonekamp NA, Kühl I. Starting the engine of the powerhouse: mitochondrial transcription and beyond. Biol Chem 2022; 403:779-805. [PMID: 35355496 DOI: 10.1515/hsz-2021-0416] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/09/2022] [Indexed: 12/25/2022]
Abstract
Mitochondria are central hubs for cellular metabolism, coordinating a variety of metabolic reactions crucial for human health. Mitochondria provide most of the cellular energy via their oxidative phosphorylation (OXPHOS) system, which requires the coordinated expression of genes encoded by both the nuclear (nDNA) and mitochondrial genomes (mtDNA). Transcription of mtDNA is not only essential for the biogenesis of the OXPHOS system, but also generates RNA primers necessary to initiate mtDNA replication. Like the prokaryotic system, mitochondria have no membrane-based compartmentalization to separate the different steps of mtDNA maintenance and expression and depend entirely on nDNA-encoded factors imported into the organelle. Our understanding of mitochondrial transcription in mammalian cells has largely progressed, but the mechanisms regulating mtDNA gene expression are still poorly understood despite their profound importance for human disease. Here, we review mechanisms of mitochondrial gene expression with a focus on the recent findings in the field of mammalian mtDNA transcription and disease phenotypes caused by defects in proteins involved in this process.
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Affiliation(s)
- Maria Miranda
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, D-50931, Germany
| | - Nina A Bonekamp
- Department of Neuroanatomy, Mannheim Center for Translational Neurosciences (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, D-68167, Germany
| | - Inge Kühl
- Department of Cell Biology, Institute of Integrative Biology of the Cell (I2BC), UMR9198, CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, F-91190, France
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25
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Singh M, Posse V, Peter B, Falkenberg M, Gustafsson C. Ribonucleotides embedded in template DNA impair mitochondrial RNA polymerase progression. Nucleic Acids Res 2022; 50:989-999. [PMID: 35018464 PMCID: PMC8789056 DOI: 10.1093/nar/gkab1251] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 11/30/2021] [Accepted: 12/07/2021] [Indexed: 11/12/2022] Open
Abstract
Human mitochondria lack ribonucleotide excision repair pathways, causing misincorporated ribonucleotides (rNMPs) to remain embedded in the mitochondrial genome. Previous studies have demonstrated that human mitochondrial DNA polymerase γ can bypass a single rNMP, but that longer stretches of rNMPs present an obstacle to mitochondrial DNA replication. Whether embedded rNMPs also affect mitochondrial transcription has not been addressed. Here we demonstrate that mitochondrial RNA polymerase elongation activity is affected by a single, embedded rNMP in the template strand. The effect is aggravated at stretches with two or more consecutive rNMPs in a row and cannot be overcome by addition of the mitochondrial transcription elongation factor TEFM. Our findings lead us to suggest that impaired transcription may be of functional relevance in genetic disorders associated with imbalanced nucleotide pools and higher levels of embedded rNMPs.
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Affiliation(s)
- Meenakshi Singh
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Viktor Posse
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
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26
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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: 2.3] [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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27
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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: 12] [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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28
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Bonekamp NA, Jiang M, Motori E, Garcia Villegas R, Koolmeister C, Atanassov I, Mesaros A, Park CB, Larsson NG. High levels of TFAM repress mammalian mitochondrial DNA transcription in vivo. Life Sci Alliance 2021; 4:4/11/e202101034. [PMID: 34462320 PMCID: PMC8408345 DOI: 10.26508/lsa.202101034] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 08/10/2021] [Accepted: 08/20/2021] [Indexed: 01/04/2023] Open
Abstract
Mitochondrial transcription factor A (TFAM) is compacting mitochondrial DNA (dmtDNA) into nucleoids and directly controls mtDNA copy number. Here, we show that the TFAM-to-mtDNA ratio is critical for maintaining normal mtDNA expression in different mouse tissues. Moderately increased TFAM protein levels increase mtDNA copy number but a normal TFAM-to-mtDNA ratio is maintained resulting in unaltered mtDNA expression and normal whole animal metabolism. Mice ubiquitously expressing very high TFAM levels develop pathology leading to deficient oxidative phosphorylation (OXPHOS) and early postnatal lethality. The TFAM-to-mtDNA ratio varies widely between tissues in these mice and is very high in skeletal muscle leading to strong repression of mtDNA expression and OXPHOS deficiency. In the heart, increased mtDNA copy number results in a near normal TFAM-to-mtDNA ratio and maintained OXPHOS capacity. In liver, induction of LONP1 protease and mitochondrial RNA polymerase expression counteracts the silencing effect of high TFAM levels. TFAM thus acts as a general repressor of mtDNA expression and this effect can be counterbalanced by tissue-specific expression of regulatory factors.
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Affiliation(s)
- Nina A Bonekamp
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Min Jiang
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany.,Zhejiang Provincial Laboratory of Life Sciences and Biomedicine, Key Laboratory of Growth Regulation and Transformation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Elisa Motori
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | | | - Camilla Koolmeister
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ilian Atanassov
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Andrea Mesaros
- Phenotyping Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany .,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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29
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Menger KE, Rodríguez-Luis A, Chapman J, Nicholls TJ. Controlling the topology of mammalian mitochondrial DNA. Open Biol 2021; 11:210168. [PMID: 34547213 PMCID: PMC8455175 DOI: 10.1098/rsob.210168] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The genome of mitochondria, called mtDNA, is a small circular DNA molecule present at thousands of copies per human cell. MtDNA is packaged into nucleoprotein complexes called nucleoids, and the density of mtDNA packaging affects mitochondrial gene expression. Genetic processes such as transcription, DNA replication and DNA packaging alter DNA topology, and these topological problems are solved by a family of enzymes called topoisomerases. Within mitochondria, topoisomerases are involved firstly in the regulation of mtDNA supercoiling and secondly in disentangling interlinked mtDNA molecules following mtDNA replication. The loss of mitochondrial topoisomerase activity leads to defects in mitochondrial function, and variants in the dual-localized type IA topoisomerase TOP3A have also been reported to cause human mitochondrial disease. We review the current knowledge on processes that alter mtDNA topology, how mtDNA topology is modulated by the action of topoisomerases, and the consequences of altered mtDNA topology for mitochondrial function and human health.
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Affiliation(s)
- Katja E. Menger
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Alejandro Rodríguez-Luis
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - James Chapman
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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30
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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: 48] [Impact Index Per Article: 12.0] [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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31
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Wang LJ, Hsu T, Lin HL, Fu CY. Modulation of mitochondrial nucleoid structure during aging and by mtDNA content in Drosophila. Biol Open 2021; 10:269285. [PMID: 34180963 PMCID: PMC8380045 DOI: 10.1242/bio.058553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 04/07/2021] [Indexed: 12/02/2022] Open
Abstract
Mitochondrial DNA (mtDNA) encodes gene products that are essential for oxidative phosphorylation. They organize as higher order nucleoid structures (mtNucleoids) that were shown to be critical for the maintenance of mtDNA stability and integrity. While mtNucleoid structures are associated with cellular health, how they change in situ under physiological maturation and aging requires further investigation. In this study, we investigated the mtNucleoid assembly at an ultrastructural level in situ using the TFAM-Apex2 Drosophila model. We found that smaller and more compact TFAM-nucleoids are populated in the mitochondria of indirect flight muscle of aged flies. Furthermore, mtDNA transcription and replication were cross-regulated in the mtTFB2-knockdown flies as in the mtRNAPol-knockdown flies that resulted in reductions in mtDNA copy numbers and nucleoid-associated TFAM. Overall, our study reveals that the modulation of TFAM-nucleoid structure under physiological aging, which is critically regulated by mtDNA content. Summary: The TFAM-nucleoid structure is critically regulated by mtDNA content and changes during aging. Mitochondrial transcription factor B2 plays a role in mtDNA replication.
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Affiliation(s)
- Li-Jie Wang
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Tian Hsu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Hsiang-Ling Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chi-Yu Fu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
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32
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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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33
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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: 13] [Impact Index Per Article: 3.3] [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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34
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Mitochondrial genome stability in human: understanding the role of DNA repair pathways. Biochem J 2021; 478:1179-1197. [DOI: 10.1042/bcj20200920] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/15/2021] [Accepted: 02/17/2021] [Indexed: 11/17/2022]
Abstract
Mitochondria are semiautonomous organelles in eukaryotic cells and possess their own genome that replicates independently. Mitochondria play a major role in oxidative phosphorylation due to which its genome is frequently exposed to oxidative stress. Factors including ionizing radiation, radiomimetic drugs and replication fork stalling can also result in different types of mutations in mitochondrial DNA (mtDNA) leading to genome fragility. Mitochondria from myopathies, dystonia, cancer patient samples show frequent mtDNA mutations such as point mutations, insertions and large-scale deletions that could account for mitochondria-associated disease pathogenesis. The mechanism by which such mutations arise following exposure to various DNA-damaging agents is not well understood. One of the well-studied repair pathways in mitochondria is base excision repair. Other repair pathways such as mismatch repair, homologous recombination and microhomology-mediated end joining have also been reported. Interestingly, nucleotide excision repair and classical nonhomologous DNA end joining are not detected in mitochondria. In this review, we summarize the potential causes of mitochondrial genome fragility, their implications as well as various DNA repair pathways that operate in mitochondria.
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Oláhová M, Peter B, Szilagyi Z, Diaz-Maldonado H, Singh M, Sommerville EW, Blakely EL, Collier JJ, Hoberg E, Stránecký V, Hartmannová H, Bleyer AJ, McBride KL, Bowden SA, Korandová Z, Pecinová A, Ropers HH, Kahrizi K, Najmabadi H, Tarnopolsky MA, Brady LI, Weaver KN, Prada CE, Õunap K, Wojcik MH, Pajusalu S, Syeda SB, Pais L, Estrella EA, Bruels CC, Kunkel LM, Kang PB, Bonnen PE, Mráček T, Kmoch S, Gorman GS, Falkenberg M, Gustafsson CM, Taylor RW. POLRMT mutations impair mitochondrial transcription causing neurological disease. Nat Commun 2021; 12:1135. [PMID: 33602924 PMCID: PMC7893070 DOI: 10.1038/s41467-021-21279-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 12/18/2020] [Indexed: 02/06/2023] Open
Abstract
While >300 disease-causing variants have been identified in the mitochondrial DNA (mtDNA) polymerase γ, no mitochondrial phenotypes have been associated with POLRMT, the RNA polymerase responsible for transcription of the mitochondrial genome. Here, we characterise the clinical and molecular nature of POLRMT variants in eight individuals from seven unrelated families. Patients present with global developmental delay, hypotonia, short stature, and speech/intellectual disability in childhood; one subject displayed an indolent progressive external ophthalmoplegia phenotype. Massive parallel sequencing of all subjects identifies recessive and dominant variants in the POLRMT gene. Patient fibroblasts have a defect in mitochondrial mRNA synthesis, but no mtDNA deletions or copy number abnormalities. The in vitro characterisation of the recombinant POLRMT mutants reveals variable, but deleterious effects on mitochondrial transcription. Together, our in vivo and in vitro functional studies of POLRMT variants establish defective mitochondrial transcription as an important disease mechanism.
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Affiliation(s)
- Monika Oláhová
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Zsolt Szilagyi
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Hector Diaz-Maldonado
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Meenakshi Singh
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Ewen W Sommerville
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Jack J Collier
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Emily Hoberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Viktor Stránecký
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
| | - Hana Hartmannová
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
| | - Anthony J Bleyer
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
- Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, USA
| | - Kim L McBride
- Center for Cardiovascular and Pulmonary Research, Department of Pediatrics, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, USA
| | - Sasigarn A Bowden
- Division of Endocrinology, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, USA
| | - Zuzana Korandová
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
- Department of Bioenergetics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Alena Pecinová
- Department of Bioenergetics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Hans-Hilger Ropers
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
- Institute of Human Genetics, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Kimia Kahrizi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mark A Tarnopolsky
- Department of Pediatric and Medicines, Division of Neuromuscular and Neurometabolic Diseases, McMaster University Children's Hospital, Hamilton, Canada
| | - Lauren I Brady
- Department of Pediatric and Medicines, Division of Neuromuscular and Neurometabolic Diseases, McMaster University Children's Hospital, Hamilton, Canada
| | - K Nicole Weaver
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Carlos E Prada
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Department of Pediatrics, Cardiovascular Foundation of Colombia, Floridablanca, Colombia
| | - Katrin Õunap
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Monica H Wojcik
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Divisions of Newborn Medicine and Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Sander Pajusalu
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Safoora B Syeda
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
| | - Lynn Pais
- Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Elicia A Estrella
- Division of Genetics & Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Christine C Bruels
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
| | - Louis M Kunkel
- Division of Genetics & Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Peter B Kang
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
- Department of Molecular Genetics & Microbiology, and Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA
- Genetics Institute and Myology Institute, University of Florida, Gainesville, FL, USA
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Tomáš Mráček
- Department of Bioenergetics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Stanislav Kmoch
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - 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.
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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Fontana GA, Gahlon HL. Mechanisms of replication and repair in mitochondrial DNA deletion formation. Nucleic Acids Res 2020; 48:11244-11258. [PMID: 33021629 PMCID: PMC7672454 DOI: 10.1093/nar/gkaa804] [Citation(s) in RCA: 135] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/07/2020] [Accepted: 09/25/2020] [Indexed: 02/06/2023] Open
Abstract
Deletions in mitochondrial DNA (mtDNA) are associated with diverse human pathologies including cancer, aging and mitochondrial disorders. Large-scale deletions span kilobases in length and the loss of these associated genes contributes to crippled oxidative phosphorylation and overall decline in mitochondrial fitness. There is not a united view for how mtDNA deletions are generated and the molecular mechanisms underlying this process are poorly understood. This review discusses the role of replication and repair in mtDNA deletion formation as well as nucleic acid motifs such as repeats, secondary structures, and DNA damage associated with deletion formation in the mitochondrial genome. We propose that while erroneous replication and repair can separately contribute to deletion formation, crosstalk between these pathways is also involved in generating deletions.
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Affiliation(s)
- Gabriele A Fontana
- Department of Health Sciences and Technology, ETH Zürich, Schmelzbergstrasse 9, 8092 Zürich, Switzerland
| | - Hailey L Gahlon
- To whom correspondence should be addressed. Tel: +41 44 632 3731;
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Basu U, Bostwick AM, Das K, Dittenhafer-Reed KE, Patel SS. Structure, mechanism, and regulation of mitochondrial DNA transcription initiation. J Biol Chem 2020; 295:18406-18425. [PMID: 33127643 PMCID: PMC7939475 DOI: 10.1074/jbc.rev120.011202] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 10/29/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are specialized compartments that produce requisite ATP to fuel cellular functions and serve as centers of metabolite processing, cellular signaling, and apoptosis. To accomplish these roles, mitochondria rely on the genetic information in their small genome (mitochondrial DNA) and the nucleus. A growing appreciation for mitochondria's role in a myriad of human diseases, including inherited genetic disorders, degenerative diseases, inflammation, and cancer, has fueled the study of biochemical mechanisms that control mitochondrial function. The mitochondrial transcriptional machinery is different from nuclear machinery. The in vitro re-constituted transcriptional complexes of Saccharomyces cerevisiae (yeast) and humans, aided with high-resolution structures and biochemical characterizations, have provided a deeper understanding of the mechanism and regulation of mitochondrial DNA transcription. In this review, we will discuss recent advances in the structure and mechanism of mitochondrial transcription initiation. We will follow up with recent discoveries and formative findings regarding the regulatory events that control mitochondrial DNA transcription, focusing on those involved in cross-talk between the mitochondria and nucleus.
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Affiliation(s)
- Urmimala Basu
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA; Graduate School of Biomedical Sciences, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | | | - Kalyan Das
- Department of Microbiology, Immunology, and Transplantation, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
| | | | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA.
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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: 271] [Impact Index Per Article: 54.2] [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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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: 43] [Impact Index Per Article: 8.6] [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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40
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Chapman J, Ng YS, Nicholls TJ. The Maintenance of Mitochondrial DNA Integrity and Dynamics by Mitochondrial Membranes. Life (Basel) 2020; 10:life10090164. [PMID: 32858900 PMCID: PMC7555930 DOI: 10.3390/life10090164] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/20/2020] [Accepted: 08/23/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are complex organelles that harbour their own genome. Mitochondrial DNA (mtDNA) exists in the form of a circular double-stranded DNA molecule that must be replicated, segregated and distributed around the mitochondrial network. Human cells typically possess between a few hundred and several thousand copies of the mitochondrial genome, located within the mitochondrial matrix in close association with the cristae ultrastructure. The organisation of mtDNA around the mitochondrial network requires mitochondria to be dynamic and undergo both fission and fusion events in coordination with the modulation of cristae architecture. The dysregulation of these processes has profound effects upon mtDNA replication, manifesting as a loss of mtDNA integrity and copy number, and upon the subsequent distribution of mtDNA around the mitochondrial network. Mutations within genes involved in mitochondrial dynamics or cristae modulation cause a wide range of neurological disorders frequently associated with defects in mtDNA maintenance. This review aims to provide an understanding of the biological mechanisms that link mitochondrial dynamics and mtDNA integrity, as well as examine the interplay that occurs between mtDNA, mitochondrial dynamics and cristae structure.
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Affiliation(s)
- James Chapman
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
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41
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Peter B, Falkenberg M. TWINKLE and Other Human Mitochondrial DNA Helicases: Structure, Function and Disease. Genes (Basel) 2020; 11:genes11040408. [PMID: 32283748 PMCID: PMC7231222 DOI: 10.3390/genes11040408] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/30/2022] Open
Abstract
Mammalian mitochondria contain a circular genome (mtDNA) which encodes subunits of the oxidative phosphorylation machinery. The replication and maintenance of mtDNA is carried out by a set of nuclear-encoded factors—of which, helicases form an important group. The TWINKLE helicase is the main helicase in mitochondria and is the only helicase required for mtDNA replication. Mutations in TWINKLE cause a number of human disorders associated with mitochondrial dysfunction, neurodegeneration and premature ageing. In addition, a number of other helicases with a putative role in mitochondria have been identified. In this review, we discuss our current knowledge of TWINKLE structure and function and its role in diseases of mtDNA maintenance. We also briefly discuss other potential mitochondrial helicases and postulate on their role(s) in mitochondria.
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Hoyos-Gonzalez N, Trasviña-Arenas CH, Degiorgi A, Castro-Lara AY, Peralta-Castro A, Jimenez-Sandoval P, Diaz-Quezada C, Lodi T, Baruffini E, Brieba LG. Modeling of pathogenic variants of mitochondrial DNA polymerase: insight into the replication defects and implication for human disease. Biochim Biophys Acta Gen Subj 2020; 1864:129608. [PMID: 32234506 DOI: 10.1016/j.bbagen.2020.129608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 03/07/2020] [Accepted: 03/25/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Mutations in human gene encoding the mitochondrial DNA polymerase γ (HsPolγ) are associated with a broad range of mitochondrial diseases. Here we studied the impact on DNA replication by disease variants clustered around residue HsPolγ-K1191, a residue that in several family-A DNA polymerases interacts with the 3' end of the primer. METHODS Specifically, we examined the effect of HsPolγ carrying pathogenic variants in residues D1184, I1185, C1188, K1191, D1196, and a stop codon at residue T1199, using as a model the yeast mitochondrial DNA polymerase protein, Mip1p. RESULTS The introduction of pathogenic variants C1188R (yV945R), and of a stop codon at residue T1199 (yT956X) abolished both polymerization and exonucleolysis in vitro. HsPolγ substitutions in residues D1184 (yD941), I1185 (yI942), K1191 (yK948) and D1196 (yD953) shifted the balance between polymerization and exonucleolysis in favor of exonucleolysis. HsPolγ pathogenic variants at residue K1191 (yK948) and D1184 (yD941) were capable of nucleotide incorporation albeit with reduced processivity. Structural analysis of mitochondrial DNAPs showed that residue HsPolγ-N864 is placed in an optimal distance to interact with the 3' end of the primer and the phosphate backbone previous to the 3' end. Amino acid changes in residue HsPolγ-N864 to Ala, Ser or Asp result in enzymes that did not decrease their polymerization activity on short templates but exhibited a substantial decrease for processive DNA synthesis. CONCLUSION Our data suggest that in mitochondrial DNA polymerases multiple amino acids are involved in the primer-stand stabilization.
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Affiliation(s)
- Nallely Hoyos-Gonzalez
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Carlos H Trasviña-Arenas
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Andrea Degiorgi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Atzimaba Y Castro-Lara
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Antolín Peralta-Castro
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Pedro Jimenez-Sandoval
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Corina Diaz-Quezada
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico
| | - Tiziana Lodi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
| | - Luis G Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, CP 36821 Irapuato, Guanajuato, Mexico.
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Nava GM, Grasso L, Sertic S, Pellicioli A, Muzi Falconi M, Lazzaro F. One, No One, and One Hundred Thousand: The Many Forms of Ribonucleotides in DNA. Int J Mol Sci 2020; 21:E1706. [PMID: 32131532 PMCID: PMC7084774 DOI: 10.3390/ijms21051706] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/26/2020] [Accepted: 02/28/2020] [Indexed: 12/14/2022] Open
Abstract
In the last decade, it has become evident that RNA is frequently found in DNA. It is now well established that single embedded ribonucleoside monophosphates (rNMPs) are primarily introduced by DNA polymerases and that longer stretches of RNA can anneal to DNA, generating RNA:DNA hybrids. Among them, the most studied are R-loops, peculiar three-stranded nucleic acid structures formed upon the re-hybridization of a transcript to its template DNA. In addition, polyribonucleotide chains are synthesized to allow DNA replication priming, double-strand breaks repair, and may as well result from the direct incorporation of consecutive rNMPs by DNA polymerases. The bright side of RNA into DNA is that it contributes to regulating different physiological functions. The dark side, however, is that persistent RNA compromises genome integrity and genome stability. For these reasons, the characterization of all these structures has been under growing investigation. In this review, we discussed the origin of single and multiple ribonucleotides in the genome and in the DNA of organelles, focusing on situations where the aberrant processing of RNA:DNA hybrids may result in multiple rNMPs embedded in DNA. We concluded by providing an overview of the currently available strategies to study the presence of single and multiple ribonucleotides in DNA in vivo.
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Affiliation(s)
| | | | | | | | - Marco Muzi Falconi
- Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy; (G.M.N.); (L.G.); (S.S.); (A.P.)
| | - Federico Lazzaro
- Dipartimento di Bioscienze, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy; (G.M.N.); (L.G.); (S.S.); (A.P.)
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Abstract
Mitochondrial dysfunction or loss is evident in neurodegenerative diseases. Furthermore, mitochondrial DNA (mtDNA) mutations associated with NADH dehydrogenase subunits and nuclear gene mutations that affect mitochondrial function result in optic neuropathies. In this issue of the JCI, Del Dotto et al. and Piro-Mégy et al. identify heterozygous mutations in nuclear-encoded mitochondrial single-strand binding protein 1 (SSBP1) in patients with apparently dominant optic neuropathy with or without extraocular phenotypes. Both research groups reported similar mitochondrial findings in response to SSBP1 mutations. However, the specific SSBP1 mitochondria-associated function in retinal ganglion cells (RGCs) and the resulting optic nerve remains unclear. We suggest that high expression of SSBP1 during RGC differentiation is critical for mtDNA maintenance to produce appropriate optic nerve connectivity and that SSBP1 mutations in dominant optic atrophy patients do not permit stable binding to N6-methyldeoxyadenosine on the heavy strand involved with replication, leading to disruptions of mtDNA and, eventually, optic nerve dysfunction.
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Matkarimov BT, Saparbaev MK. DNA Repair and Mutagenesis in Vertebrate Mitochondria: Evidence for Asymmetric DNA Strand Inheritance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1241:77-100. [DOI: 10.1007/978-3-030-41283-8_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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46
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Brieba LG. Structure-Function Analysis Reveals the Singularity of Plant Mitochondrial DNA Replication Components: A Mosaic and Redundant System. PLANTS 2019; 8:plants8120533. [PMID: 31766564 PMCID: PMC6963530 DOI: 10.3390/plants8120533] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023]
Abstract
Plants are sessile organisms, and their DNA is particularly exposed to damaging agents. The integrity of plant mitochondrial and plastid genomes is necessary for cell survival. During evolution, plants have evolved mechanisms to replicate their mitochondrial genomes while minimizing the effects of DNA damaging agents. The recombinogenic character of plant mitochondrial DNA, absence of defined origins of replication, and its linear structure suggest that mitochondrial DNA replication is achieved by a recombination-dependent replication mechanism. Here, I review the mitochondrial proteins possibly involved in mitochondrial DNA replication from a structural point of view. A revision of these proteins supports the idea that mitochondrial DNA replication could be replicated by several processes. The analysis indicates that DNA replication in plant mitochondria could be achieved by a recombination-dependent replication mechanism, but also by a replisome in which primers are synthesized by three different enzymes: Mitochondrial RNA polymerase, Primase-Helicase, and Primase-Polymerase. The recombination-dependent replication model and primers synthesized by the Primase-Polymerase may be responsible for the presence of genomic rearrangements in plant mitochondria.
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Affiliation(s)
- Luis Gabriel Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato C.P. 36821, Mexico
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Estep KN, Butler TJ, Ding J, Brosh RM. G4-Interacting DNA Helicases and Polymerases: Potential Therapeutic Targets. Curr Med Chem 2019; 26:2881-2897. [PMID: 29149833 DOI: 10.2174/0929867324666171116123345] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 10/16/2017] [Accepted: 10/16/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND Guanine-rich DNA can fold into highly stable four-stranded DNA structures called G-quadruplexes (G4). In recent years, the G-quadruplex field has blossomed as new evidence strongly suggests that such alternately folded DNA structures are likely to exist in vivo. G4 DNA presents obstacles for the replication machinery, and both eukaryotic DNA helicases and polymerases have evolved to resolve and copy G4 DNA in vivo. In addition, G4-forming sequences are prevalent in gene promoters, suggesting that G4-resolving helicases act to modulate transcription. METHODS We have searched the PubMed database to compile an up-to-date and comprehensive assessment of the field's current knowledge to provide an overview of the molecular interactions of Gquadruplexes with DNA helicases and polymerases implicated in their resolution. RESULTS Novel computational tools and alternative strategies have emerged to detect G4-forming sequences and assess their biological consequences. Specialized DNA helicases and polymerases catalytically act upon G4-forming sequences to maintain normal replication and genomic stability as well as appropriate gene regulation and cellular homeostasis. G4 helicases also resolve telomeric repeats to maintain chromosomal DNA ends. Bypass of many G4-forming sequences is achieved by the action of translesion DNS polymerases or the PrimPol DNA polymerase. While the collective work has supported a role of G4 in nuclear DNA metabolism, an emerging field centers on G4 abundance in the mitochondrial genome. CONCLUSION Discovery of small molecules that specifically bind and modulate DNA helicases and polymerases or interact with the G4 DNA structure itself may be useful for the development of anticancer regimes.
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Affiliation(s)
- Katrina N Estep
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
| | - Thomas J Butler
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
| | - Jun Ding
- Laboratory of Genetics and Genomics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
| | - Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Blvd Baltimore, MD 21224, United States
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Bouda E, Stapon A, Garcia-Diaz M. Mechanisms of mammalian mitochondrial transcription. Protein Sci 2019; 28:1594-1605. [PMID: 31309618 DOI: 10.1002/pro.3688] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 07/10/2019] [Accepted: 07/11/2019] [Indexed: 01/06/2023]
Abstract
Numerous age-related human diseases have been associated with deficiencies in cellular energy production. Moreover, genetic alterations resulting in mitochondrial dysfunction are the cause of inheritable disorders commonly known as mitochondrial diseases. Many of these deficiencies have been directly or indirectly linked to deficits in mitochondrial gene expression. Transcription is an essential step in gene expression and elucidating the molecular mechanisms involved in this process is critical for understanding defects in energy production. For the past five decades, substantial efforts have been invested in the field of mitochondrial transcription. These efforts have led to the discovery of the main protein factors responsible for transcription as well as to a basic mechanistic understanding of the transcription process. They have also revealed various mechanisms of transcriptional regulation as well as the links that exist between the transcription process and downstream processes of RNA maturation. Here, we review the knowledge gathered in early mitochondrial transcription studies and focus on recent findings that shape our current understanding of mitochondrial transcription, posttranscriptional processing, as well as transcriptional regulation in mammalian systems.
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Affiliation(s)
- Emilie Bouda
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
| | - Anthony Stapon
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
| | - Miguel Garcia-Diaz
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
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Blanco L, Calvo PA, Diaz-Talavera A, Carvalho G, Calero N, Martínez-Carrón A, Velázquez-Ruiz C, Villadangos S, Guerra S, Martínez-Jiménez MI. Mechanism of DNA primer synthesis by human PrimPol. Enzymes 2019; 45:289-310. [PMID: 31627881 DOI: 10.1016/bs.enz.2019.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PrimPol is the second primase discovered in eukaryotic cells, whose function is to restart the stalled replication forks during both mitochondrial and nuclear DNA replication. This chapter revises our current knowledge about the mechanism of synthesis of DNA primers by human PrimPol, and the importance of its distinctive Zn-finger domain (ZnFD). After PrimPol forms a binary complex with ssDNA, the formation of the pre-ternary complex strictly requires the presence of Mn2+ ions to stabilize the interaction of the incoming deoxynucleotide at the 3'-site. The capacity to bind both ssDNA template and 3'-deoxynucleotide was shown to reside in the AEP core of PrimPol, with ZnFD being dispensable at these two early steps of the primase reaction. Sugar selection favoring dNTPs versus NTPs at the 3' site is mediated by a specific tyrosine (Tyr100) acting as a steric gate. Besides, a specific glutamate residue (Glu116) conforming a singular A motif (DxE) promotes the use of Mn2+ to stabilize the pre-ternary complex. Mirroring the function of the PriL subunit of dimeric AEP primases, the ZnFD of PrimPol is crucial to stabilize the initiating 5'-nucleotide, specifically interacting with the gamma-phosphate. Such an interaction is crucial to optimize dimer formation and the subsequent translocation events leading to the processive synthesis of a mature DNA primer. Finally, the capacity of PrimPol to tolerate lesions is discussed in the context of its DNA primase function, and its potential as a TLS primase.
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Affiliation(s)
- Luis Blanco
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain.
| | - Patricia A Calvo
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | | | - Gustavo Carvalho
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Nieves Calero
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | | | | | | | - Susana Guerra
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
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Wanrooij PH, Chabes A. Ribonucleotides in mitochondrial DNA. FEBS Lett 2019; 593:1554-1565. [PMID: 31093968 DOI: 10.1002/1873-3468.13440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/09/2019] [Accepted: 05/09/2019] [Indexed: 01/05/2023]
Abstract
The incorporation of ribonucleotides (rNMPs) into DNA during genome replication has gained substantial attention in recent years and has been shown to be a significant source of genomic instability. Studies in yeast and mammals have shown that the two genomes, the nuclear DNA (nDNA) and the mitochondrial DNA (mtDNA), differ with regard to their rNMP content. This is largely due to differences in rNMP repair - whereas rNMPs are efficiently removed from the nuclear genome, mitochondria lack robust mechanisms for removal of single rNMPs incorporated during DNA replication. In this minireview, we describe the processes that determine the frequency of rNMPs in the mitochondrial genome and summarise recent findings regarding the effect of incorporated rNMPs on mtDNA stability and function.
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Affiliation(s)
- Paulina H Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Sweden.,Laboratory for Molecular Infection Medicine Sweden, Umeå University, Sweden
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