1
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Veeraragavan S, Johansen M, Johnston IG. Evolution and maintenance of mtDNA gene content across eukaryotes. Biochem J 2024; 481:1015-1042. [PMID: 39101615 PMCID: PMC11346449 DOI: 10.1042/bcj20230415] [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: 04/08/2024] [Revised: 06/26/2024] [Accepted: 07/18/2024] [Indexed: 08/06/2024]
Abstract
Across eukaryotes, most genes required for mitochondrial function have been transferred to, or otherwise acquired by, the nucleus. Encoding genes in the nucleus has many advantages. So why do mitochondria retain any genes at all? Why does the set of mtDNA genes vary so much across different species? And how do species maintain functionality in the mtDNA genes they do retain? In this review, we will discuss some possible answers to these questions, attempting a broad perspective across eukaryotes. We hope to cover some interesting features which may be less familiar from the perspective of particular species, including the ubiquity of recombination outside bilaterian animals, encrypted chainmail-like mtDNA, single genes split over multiple mtDNA chromosomes, triparental inheritance, gene transfer by grafting, gain of mtDNA recombination factors, social networks of mitochondria, and the role of mtDNA dysfunction in feeding the world. We will discuss a unifying picture where organismal ecology and gene-specific features together influence whether organism X retains mtDNA gene Y, and where ecology and development together determine which strategies, importantly including recombination, are used to maintain the mtDNA genes that are retained.
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Affiliation(s)
| | - Maria Johansen
- Department of Mathematics, University of Bergen, Bergen, Norway
| | - Iain G. Johnston
- Department of Mathematics, University of Bergen, Bergen, Norway
- Computational Biology Unit, University of Bergen, Bergen, Norway
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2
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Burr SP, Chinnery PF. Origins of tissue and cell-type specificity in mitochondrial DNA (mtDNA) disease. Hum Mol Genet 2024; 33:R3-R11. [PMID: 38779777 PMCID: PMC11112380 DOI: 10.1093/hmg/ddae059] [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: 12/21/2023] [Revised: 12/21/2023] [Accepted: 02/05/2024] [Indexed: 05/25/2024] Open
Abstract
Mutations of mitochondrial (mt)DNA are a major cause of morbidity and mortality in humans, accounting for approximately two thirds of diagnosed mitochondrial disease. However, despite significant advances in technology since the discovery of the first disease-causing mtDNA mutations in 1988, the comprehensive diagnosis and treatment of mtDNA disease remains challenging. This is partly due to the highly variable clinical presentation linked to tissue-specific vulnerability that determines which organs are affected. Organ involvement can vary between different mtDNA mutations, and also between patients carrying the same disease-causing variant. The clinical features frequently overlap with other non-mitochondrial diseases, both rare and common, adding to the diagnostic challenge. Building on previous findings, recent technological advances have cast further light on the mechanisms which underpin the organ vulnerability in mtDNA diseases, but our understanding is far from complete. In this review we explore the origins, current knowledge, and future directions of research in this area.
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Affiliation(s)
- Stephen P Burr
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0QQ, United Kingdom
| | - Patrick F Chinnery
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
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3
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Spinazzola A, Perez-Rodriguez D, Ježek J, Holt IJ. Mitochondrial DNA competition: starving out the mutant genome. Trends Pharmacol Sci 2024; 45:225-242. [PMID: 38402076 DOI: 10.1016/j.tips.2024.01.011] [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: 09/24/2023] [Revised: 01/11/2024] [Accepted: 01/22/2024] [Indexed: 02/26/2024]
Abstract
High levels of pathogenic mitochondrial DNA (mtDNA) variants lead to severe genetic diseases, and the accumulation of such mutants may also contribute to common disorders. Thus, selecting against these mutants is a major goal in mitochondrial medicine. Although mutant mtDNA can drift randomly, mounting evidence indicates that active forces play a role in the selection for and against mtDNA variants. The underlying mechanisms are beginning to be clarified, and recent studies suggest that metabolic cues, including fuel availability, contribute to shaping mtDNA heteroplasmy. In the context of pathological mtDNAs, remodeling of nutrient metabolism supports mitochondria with deleterious mtDNAs and enables them to outcompete functional variants owing to a replicative advantage. The elevated nutrient requirement represents a mutant Achilles' heel because small molecules that restrict nutrient consumption or interfere with nutrient sensing can purge cells of deleterious mtDNAs and restore mitochondrial respiration. These advances herald the dawn of a new era of small-molecule therapies to counteract pathological mtDNAs.
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Affiliation(s)
- Antonella Spinazzola
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK.
| | - Diego Perez-Rodriguez
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK
| | - Jan Ježek
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK
| | - Ian J Holt
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK; Biodonostia Health Research Institute, 20014 San Sebastián, Spain; IKERBASQUE (Basque Foundation for Science), 48013 Bilbao, Spain; CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), 28031 Madrid, Spain; Universidad de País Vasco, Barrio Sarriena s/n, 48940 Leioa, Bilbao, Spain.
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4
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Pei L, Overdahl KE, Shannon JP, Hornick KM, Jarmusch AK, Hickman HD. Profiling whole-tissue metabolic reprogramming during cutaneous poxvirus infection and clearance. J Virol 2023; 97:e0127223. [PMID: 38009914 PMCID: PMC10734417 DOI: 10.1128/jvi.01272-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/01/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Human poxvirus infections have caused significant public health burdens both historically and recently during the unprecedented global Mpox virus outbreak. Although vaccinia virus (VACV) infection of mice is a commonly used model to explore the anti-poxvirus immune response, little is known about the metabolic changes that occur in vivo during infection. We hypothesized that the metabolome of VACV-infected skin would reflect the increased energetic requirements of both virus-infected cells and immune cells recruited to sites of infection. Therefore, we profiled whole VACV-infected skin using untargeted mass spectrometry to define the metabolome during infection, complementing these experiments with flow cytometry and transcriptomics. We identified specific metabolites, including nucleotides, itaconic acid, and glutamine, that were differentially expressed during VACV infection. Together, this study offers insight into both virus-specific and immune-mediated metabolic pathways that could contribute to the clearance of cutaneous poxvirus infection.
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Affiliation(s)
- Luxin Pei
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Kirsten E. Overdahl
- Metabolomics Core Facility, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - John P. Shannon
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Katherine M. Hornick
- Collaborative Bioinformatics Resource, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Alan K. Jarmusch
- Metabolomics Core Facility, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Heather D. Hickman
- Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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5
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Tsyba N, Feng G, Grub LK, Held JP, Strozak AM, Burkewitz K, Patel MR. Tissue-specific heteroplasmy segregation is accompanied by a sharp mtDNA decline in Caenorhabditis elegans soma. iScience 2023; 26:106349. [PMID: 36968071 PMCID: PMC10031119 DOI: 10.1016/j.isci.2023.106349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/08/2022] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Mutations in the mitochondrial genome (mtDNA) can be pathogenic. Owing to the multi-copy nature of mtDNA, wild-type copies can compensate for the effects of mutant mtDNA. Wild-type copies available for compensation vary depending on the mutant load and the total copy number. Here, we examine both mutant load and copy number in the tissues of Caenorhabditis elegans. We found that neurons, but not muscles, have modestly higher mutant load than rest of the soma. We also uncovered different effect of aak-2 knockout on the mutant load in the two tissues. The most surprising result was a sharp decline in somatic mtDNA content over time. The scale of the copy number decline surpasses the modest shifts in mutant load, suggesting that it may exert a substantial effect on mitochondrial function. In summary, measuring both the copy number and the mutant load provides a more comprehensive view of the mutant mtDNA dynamics.
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Affiliation(s)
- Nikita Tsyba
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - Gaomin Feng
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN37232, USA
| | - Lantana K. Grub
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - James P. Held
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - Adrianna M. Strozak
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
| | - Kristopher Burkewitz
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN37232, USA
| | - Maulik R. Patel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN37232, USA
- Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN37232, USA
- Evolutionary Studies, Vanderbilt University, Nashville, TN37235, USA
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6
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Chiaratti MR, Chinnery PF. Modulating mitochondrial DNA mutations: factors shaping heteroplasmy in the germ line and somatic cells. Pharmacol Res 2022; 185:106466. [PMID: 36174964 DOI: 10.1016/j.phrs.2022.106466] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/21/2022] [Accepted: 09/23/2022] [Indexed: 11/30/2022]
Abstract
Until recently it was thought that most humans only harbor one type of mitochondrial DNA (mtDNA), however, deep sequencing and single-cell analysis has shown the converse - that mixed populations of mtDNA (heteroplasmy) are the norm. This is important because heteroplasmy levels can change dramatically during transmission in the female germ line, leading to high levels causing severe mitochondrial diseases. There is also emerging evidence that low level mtDNA mutations contribute to common late onset diseases such as neurodegenerative disorders and cardiometabolic diseases because the inherited mutation levels can change within developing organs and non-dividing cells over time. Initial predictions suggested that the segregation of mtDNA heteroplasmy was largely stochastic, with an equal tendency for levels to increase or decrease. However, transgenic animal work and single-cell analysis have shown this not to be the case during germ-line transmission and in somatic tissues during life. Mutation levels in specific mtDNA regions can increase or decrease in different contexts and the underlying molecular mechanisms are starting to be unraveled. In this review we provide a synthesis of recent literature on the mechanisms of selection for and against mtDNA variants. We identify the most pertinent gaps in our understanding and suggest ways these could be addressed using state of the art techniques.
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Affiliation(s)
- Marcos R Chiaratti
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil.
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK; Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.
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7
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Nicotinamide Riboside Supplementation to Suckling Male Mice Improves Lipid and Energy Metabolism in Skeletal Muscle and Liver in Adulthood. Nutrients 2022; 14:nu14112259. [PMID: 35684059 PMCID: PMC9182637 DOI: 10.3390/nu14112259] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/25/2022] [Accepted: 05/26/2022] [Indexed: 02/04/2023] Open
Abstract
Nicotinamide riboside, an NAD+ precursor, has been attracting a lot of attention in recent years due to its potential benefits against multiple metabolic complications and age-related disorders related to NAD+ decline in tissues. The metabolic programming activity of NR supplementation in early-life stages is much less known. Here, we studied the long-term programming effects of mild NR supplementation during the suckling period on lipid and oxidative metabolism in skeletal muscle and liver tissues using an animal model. Suckling male mice received a daily oral dose of NR or vehicle (water) from day 2 to 20 of age, were weaned at day 21 onto a chow diet, and at day 90 were distributed to either a high-fat diet (HFD) or a normal-fat diet for 10 weeks. Compared to controls, NR-treated mice were protected against HFD-induced triacylglycerol accumulation in skeletal muscle and displayed lower triacylglycerol levels and steatosis degree in the liver and distinct capacities for fat oxidation and decreased lipogenesis in both tissues, paralleling signs of enhanced sirtuin 1 and AMP-dependent protein kinase signaling. These pre-clinical findings suggest that mild NR supplementation in early postnatal life beneficially impacts lipid and energy metabolism in skeletal muscle and liver in adulthood, serving as a potential preventive strategy against obesity-related disorders characterized by ectopic lipid accumulation.
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8
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Venit T, El Said NH, Mahmood SR, Percipalle P. A dynamic actin-dependent nucleoskeleton and cell identity. J Biochem 2021; 169:243-257. [PMID: 33351909 DOI: 10.1093/jb/mvaa133] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 10/27/2020] [Indexed: 12/19/2022] Open
Abstract
Actin is an essential regulator of cellular functions. In the eukaryotic cell nucleus, actin regulates chromatin as a bona fide component of chromatin remodelling complexes, it associates with nuclear RNA polymerases to regulate transcription and is involved in co-transcriptional assembly of nascent RNAs into ribonucleoprotein complexes. Actin dynamics are, therefore, emerging as a major regulatory factor affecting diverse cellular processes. Importantly, the involvement of actin dynamics in nuclear functions is redefining the concept of nucleoskeleton from a rigid scaffold to a dynamic entity that is likely linked to the three-dimensional organization of the nuclear genome. In this review, we discuss how nuclear actin, by regulating chromatin structure through phase separation may contribute to the architecture of the nuclear genome during cell differentiation and facilitate the expression of specific gene programs. We focus specifically on mitochondrial genes and how their dysregulation in the absence of actin raises important questions about the role of cytoskeletal proteins in regulating chromatin structure. The discovery of a novel pool of mitochondrial actin that serves as 'mitoskeleton' to facilitate organization of mtDNA supports a general role for actin in genome architecture and a possible function of distinct actin pools in the communication between nucleus and mitochondria.
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Affiliation(s)
- Tomas Venit
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), PO Box 129188, Abu Dhabi United Arab Emirates
| | - Nadine Hosny El Said
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), PO Box 129188, Abu Dhabi United Arab Emirates
| | - Syed Raza Mahmood
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), PO Box 129188, Abu Dhabi United Arab Emirates.,Department of Biology, New York University, 100 Washington Square East, 1009 Silver Center, New York, NY 10003, USA
| | - Piergiorgio Percipalle
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), PO Box 129188, Abu Dhabi United Arab Emirates.,Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius väg 20C, 114 18 Stockholm, Sweden
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9
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Pereira CV, Gitschlag BL, Patel MR. Cellular mechanisms of mtDNA heteroplasmy dynamics. Crit Rev Biochem Mol Biol 2021; 56:510-525. [PMID: 34120542 DOI: 10.1080/10409238.2021.1934812] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Heteroplasmy refers to the coexistence of more than one variant of the mitochondrial genome (mtDNA). Mutated or partially deleted mtDNAs can induce chronic metabolic impairment and cause mitochondrial diseases when their heteroplasmy levels exceed a critical threshold. These mutant mtDNAs can be maternally inherited or can arise de novo. Compelling evidence has emerged showing that mutant mtDNA levels can vary and change in a nonrandom fashion across generations and amongst tissues of an individual. However, our lack of understanding of the basic cellular and molecular mechanisms of mtDNA heteroplasmy dynamics has made it difficult to predict who will inherit or develop mtDNA-associated diseases. More recently, with the advances in technology and the establishment of tractable model systems, insights into the mechanisms underlying the selection forces that modulate heteroplasmy dynamics are beginning to emerge. In this review, we summarize evidence from different organisms, showing that mutant mtDNA can experience both positive and negative selection. We also review the recently identified mechanisms that modulate heteroplasmy dynamics. Taken together, this is an opportune time to survey the literature and to identify key cellular pathways that can be targeted to develop therapies for diseases caused by heteroplasmic mtDNA mutations.
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Affiliation(s)
- Claudia V Pereira
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Bryan L Gitschlag
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Maulik R Patel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.,Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA.,Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN, USA
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10
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Limoges MA, Cloutier M, Nandi M, Ilangumaran S, Ramanathan S. The GIMAP Family Proteins: An Incomplete Puzzle. Front Immunol 2021; 12:679739. [PMID: 34135906 PMCID: PMC8201404 DOI: 10.3389/fimmu.2021.679739] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/12/2021] [Indexed: 12/19/2022] Open
Abstract
Overview: Long-term survival of T lymphocytes in quiescent state is essential to maintain their cell numbers in secondary lymphoid organs and in peripheral circulation. In the BioBreeding diabetes-prone strain of rats (BB-DP), loss of functional GIMAP5 (GTPase of the immune associated nucleotide binding protein 5) results in profound peripheral T lymphopenia. This discovery heralded the identification of a new family of proteins initially called Immune-associated nucleotide binding protein (IAN) family. In this review we will use ‘GIMAP’ to refer to this family of proteins. Recent studies suggest that GIMAP proteins may interact with each other and also be involved in the movement of the cellular cargo along the cytoskeletal network. Here we will summarize the current knowledge on the characteristics and functions of GIMAP family of proteins.
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Affiliation(s)
- Marc-André Limoges
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke and CRCHUS, Sherbrooke, QC, Canada
| | - Maryse Cloutier
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke and CRCHUS, Sherbrooke, QC, Canada
| | - Madhuparna Nandi
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke and CRCHUS, Sherbrooke, QC, Canada
| | - Subburaj Ilangumaran
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke and CRCHUS, Sherbrooke, QC, Canada
| | - Sheela Ramanathan
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke and CRCHUS, Sherbrooke, QC, Canada
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11
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Walker MA, Lareau CA, Ludwig LS, Karaa A, Sankaran VG, Regev A, Mootha VK. Purifying Selection against Pathogenic Mitochondrial DNA in Human T Cells. N Engl J Med 2020; 383:1556-1563. [PMID: 32786181 PMCID: PMC7593775 DOI: 10.1056/nejmoa2001265] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many mitochondrial diseases are caused by mutations in mitochondrial DNA (mtDNA). Patients' cells contain a mixture of mutant and nonmutant mtDNA (a phenomenon called heteroplasmy). The proportion of mutant mtDNA varies across patients and among tissues within a patient. We simultaneously assayed single-cell heteroplasmy and cell state in thousands of blood cells obtained from three unrelated patients who had A3243G-associated mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes. We observed a broad range of heteroplasmy across all cell types but also found markedly reduced heteroplasmy in T cells, a finding consistent with purifying selection within this lineage. We observed this pattern in six additional patients who had heteroplasmic A3243G without strokelike episodes. (Funded by the Marriott Foundation and others.).
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Affiliation(s)
- Melissa A Walker
- From the Departments of Molecular Biology (M.A.W., V.K.M.), Neurology (M.A.W.), and Medicine (V.K.M) and the Genetics Unit, Department of Pediatrics (A.K.), Massachusetts General Hospital, Howard Hughes Medical Institute (M.A.W., A.R., V.K.M.), the Division of Hematology-Oncology, Boston Children's Hospital (C.A.L., L.S.L., V.G.S.), the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School (C.A.L., L.S.L., V.G.S.), the Department of Systems Biology, Harvard Medical School (V.K.M.), and Harvard Medical School (M.A.W., A.K.), Boston, and the Klarman Cell Observatory (L.S.L., A.R.), Broad Institute of MIT (Massachusetts Institute of Technology) and Harvard (M.A.W., C.A.L., V.G.S., V.K.M.), the Harvard Stem Cell Institute (V.G.S.), and the Department of Biology and Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology (A.R.), Cambridge - both in Massachusetts
| | - Caleb A Lareau
- From the Departments of Molecular Biology (M.A.W., V.K.M.), Neurology (M.A.W.), and Medicine (V.K.M) and the Genetics Unit, Department of Pediatrics (A.K.), Massachusetts General Hospital, Howard Hughes Medical Institute (M.A.W., A.R., V.K.M.), the Division of Hematology-Oncology, Boston Children's Hospital (C.A.L., L.S.L., V.G.S.), the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School (C.A.L., L.S.L., V.G.S.), the Department of Systems Biology, Harvard Medical School (V.K.M.), and Harvard Medical School (M.A.W., A.K.), Boston, and the Klarman Cell Observatory (L.S.L., A.R.), Broad Institute of MIT (Massachusetts Institute of Technology) and Harvard (M.A.W., C.A.L., V.G.S., V.K.M.), the Harvard Stem Cell Institute (V.G.S.), and the Department of Biology and Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology (A.R.), Cambridge - both in Massachusetts
| | - Leif S Ludwig
- From the Departments of Molecular Biology (M.A.W., V.K.M.), Neurology (M.A.W.), and Medicine (V.K.M) and the Genetics Unit, Department of Pediatrics (A.K.), Massachusetts General Hospital, Howard Hughes Medical Institute (M.A.W., A.R., V.K.M.), the Division of Hematology-Oncology, Boston Children's Hospital (C.A.L., L.S.L., V.G.S.), the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School (C.A.L., L.S.L., V.G.S.), the Department of Systems Biology, Harvard Medical School (V.K.M.), and Harvard Medical School (M.A.W., A.K.), Boston, and the Klarman Cell Observatory (L.S.L., A.R.), Broad Institute of MIT (Massachusetts Institute of Technology) and Harvard (M.A.W., C.A.L., V.G.S., V.K.M.), the Harvard Stem Cell Institute (V.G.S.), and the Department of Biology and Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology (A.R.), Cambridge - both in Massachusetts
| | - Amel Karaa
- From the Departments of Molecular Biology (M.A.W., V.K.M.), Neurology (M.A.W.), and Medicine (V.K.M) and the Genetics Unit, Department of Pediatrics (A.K.), Massachusetts General Hospital, Howard Hughes Medical Institute (M.A.W., A.R., V.K.M.), the Division of Hematology-Oncology, Boston Children's Hospital (C.A.L., L.S.L., V.G.S.), the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School (C.A.L., L.S.L., V.G.S.), the Department of Systems Biology, Harvard Medical School (V.K.M.), and Harvard Medical School (M.A.W., A.K.), Boston, and the Klarman Cell Observatory (L.S.L., A.R.), Broad Institute of MIT (Massachusetts Institute of Technology) and Harvard (M.A.W., C.A.L., V.G.S., V.K.M.), the Harvard Stem Cell Institute (V.G.S.), and the Department of Biology and Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology (A.R.), Cambridge - both in Massachusetts
| | - Vijay G Sankaran
- From the Departments of Molecular Biology (M.A.W., V.K.M.), Neurology (M.A.W.), and Medicine (V.K.M) and the Genetics Unit, Department of Pediatrics (A.K.), Massachusetts General Hospital, Howard Hughes Medical Institute (M.A.W., A.R., V.K.M.), the Division of Hematology-Oncology, Boston Children's Hospital (C.A.L., L.S.L., V.G.S.), the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School (C.A.L., L.S.L., V.G.S.), the Department of Systems Biology, Harvard Medical School (V.K.M.), and Harvard Medical School (M.A.W., A.K.), Boston, and the Klarman Cell Observatory (L.S.L., A.R.), Broad Institute of MIT (Massachusetts Institute of Technology) and Harvard (M.A.W., C.A.L., V.G.S., V.K.M.), the Harvard Stem Cell Institute (V.G.S.), and the Department of Biology and Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology (A.R.), Cambridge - both in Massachusetts
| | - Aviv Regev
- From the Departments of Molecular Biology (M.A.W., V.K.M.), Neurology (M.A.W.), and Medicine (V.K.M) and the Genetics Unit, Department of Pediatrics (A.K.), Massachusetts General Hospital, Howard Hughes Medical Institute (M.A.W., A.R., V.K.M.), the Division of Hematology-Oncology, Boston Children's Hospital (C.A.L., L.S.L., V.G.S.), the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School (C.A.L., L.S.L., V.G.S.), the Department of Systems Biology, Harvard Medical School (V.K.M.), and Harvard Medical School (M.A.W., A.K.), Boston, and the Klarman Cell Observatory (L.S.L., A.R.), Broad Institute of MIT (Massachusetts Institute of Technology) and Harvard (M.A.W., C.A.L., V.G.S., V.K.M.), the Harvard Stem Cell Institute (V.G.S.), and the Department of Biology and Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology (A.R.), Cambridge - both in Massachusetts
| | - Vamsi K Mootha
- From the Departments of Molecular Biology (M.A.W., V.K.M.), Neurology (M.A.W.), and Medicine (V.K.M) and the Genetics Unit, Department of Pediatrics (A.K.), Massachusetts General Hospital, Howard Hughes Medical Institute (M.A.W., A.R., V.K.M.), the Division of Hematology-Oncology, Boston Children's Hospital (C.A.L., L.S.L., V.G.S.), the Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School (C.A.L., L.S.L., V.G.S.), the Department of Systems Biology, Harvard Medical School (V.K.M.), and Harvard Medical School (M.A.W., A.K.), Boston, and the Klarman Cell Observatory (L.S.L., A.R.), Broad Institute of MIT (Massachusetts Institute of Technology) and Harvard (M.A.W., C.A.L., V.G.S., V.K.M.), the Harvard Stem Cell Institute (V.G.S.), and the Department of Biology and Koch Institute of Integrative Cancer Research, Massachusetts Institute of Technology (A.R.), Cambridge - both in Massachusetts
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12
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Stewart JB, Chinnery PF. Extreme heterogeneity of human mitochondrial DNA from organelles to populations. Nat Rev Genet 2020; 22:106-118. [PMID: 32989265 DOI: 10.1038/s41576-020-00284-x] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2020] [Indexed: 02/06/2023]
Abstract
Contrary to the long-held view that most humans harbour only identical mitochondrial genomes, deep resequencing has uncovered unanticipated extreme genetic variation within mitochondrial DNA (mtDNA). Most, if not all, humans contain multiple mtDNA genotypes (heteroplasmy); specific patterns of variants accumulate in different tissues, including cancers, over time; and some variants are preferentially passed down or suppressed in the maternal germ line. These findings cast light on the origin and spread of mtDNA mutations at multiple scales, from the organelle to the human population, and challenge the conventional view that high percentages of a mutation are required before a new variant has functional consequences.
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Affiliation(s)
- James B Stewart
- Max Planck Institute for Biology of Ageing, Cologne, Germany.,Wellcome Centre for Mitochondrial Research, Newcastle University Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK. .,Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK.
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13
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Røyrvik EC, Johnston IG. MtDNA sequence features associated with 'selfish genomes' predict tissue-specific segregation and reversion. Nucleic Acids Res 2020; 48:8290-8301. [PMID: 32716035 PMCID: PMC7470939 DOI: 10.1093/nar/gkaa622] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/25/2020] [Accepted: 07/15/2020] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial DNA (mtDNA) encodes cellular machinery vital for cell and organism survival. Mutations, genetic manipulation, and gene therapies may produce cells where different types of mtDNA coexist in admixed populations. In these admixtures, one mtDNA type is often observed to proliferate over another, with different types dominating in different tissues. This ‘segregation bias’ is a long-standing biological mystery that may pose challenges to modern mtDNA disease therapies, leading to substantial recent attention in biological and medical circles. Here, we show how an mtDNA sequence’s balance between replication and transcription, corresponding to molecular ‘selfishness’, in conjunction with cellular selection, can potentially modulate segregation bias. We combine a new replication-transcription-selection (RTS) model with a meta-analysis of existing data to show that this simple theory predicts complex tissue-specific patterns of segregation in mouse experiments, and reversion in human stem cells. We propose the stability of G-quadruplexes in the mtDNA control region, influencing the balance between transcription and replication primer formation, as a potential molecular mechanism governing this balance. Linking mtDNA sequence features, through this molecular mechanism, to cellular population dynamics, we use sequence data to obtain and verify the sequence-specific predictions from this hypothesis on segregation behaviour in mouse and human mtDNA.
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Affiliation(s)
- Ellen C Røyrvik
- Department of Clinical Science, University of Bergen, Norway.,K.G. Jebsen Center for Autoimmune Diseases, University of Bergen, Norway
| | - Iain G Johnston
- Department of Mathematics, University of Bergen, Norway.,Alan Turing Institute, London, UK
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14
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Evolving mtDNA populations within cells. Biochem Soc Trans 2020; 47:1367-1382. [PMID: 31484687 PMCID: PMC6824680 DOI: 10.1042/bst20190238] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/06/2019] [Accepted: 08/08/2019] [Indexed: 12/14/2022]
Abstract
Mitochondrial DNA (mtDNA) encodes vital respiratory machinery. Populations of mtDNA molecules exist in most eukaryotic cells, subject to replication, degradation, mutation, and other population processes. These processes affect the genetic makeup of cellular mtDNA populations, changing cell-to-cell distributions, means, and variances of mutant mtDNA load over time. As mtDNA mutant load has nonlinear effects on cell functionality, and cell functionality has nonlinear effects on tissue performance, these statistics of cellular mtDNA populations play vital roles in health, disease, and inheritance. This mini review will describe some of the better-known ways in which these populations change over time in different organisms, highlighting the importance of quantitatively understanding both mutant load mean and variance. Due to length constraints, we cannot attempt to be comprehensive but hope to provide useful links to some of the many excellent studies on these topics.
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15
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A Genome-wide Screen Reveals that Reducing Mitochondrial DNA Polymerase Can Promote Elimination of Deleterious Mitochondrial Mutations. Curr Biol 2019; 29:4330-4336.e3. [PMID: 31786061 PMCID: PMC6926476 DOI: 10.1016/j.cub.2019.10.060] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 10/09/2019] [Accepted: 10/29/2019] [Indexed: 02/05/2023]
Abstract
A mutant mitochondrial genome arising amid the pool of mitochondrial genomes within a cell must compete with existing genomes to survive to the next generation. Even weak selective forces can bias transmission of one genome over another to affect the inheritance of mitochondrial diseases and guide the evolution of mitochondrial DNA (mtDNA). Studies in several systems suggested that purifying selection in the female germline reduces transmission of detrimental mitochondrial mutations [1, 2, 3, 4, 5, 6, 7]. In contrast, some selfish genomes can take over despite a cost to host fitness [8, 9, 10, 11, 12, 13]. Within individuals, the outcome of competition is therefore influenced by multiple selective forces. The nuclear genome, which encodes most proteins within mitochondria, and all external regulators of mitochondrial biogenesis and dynamics can influence the competition between mitochondrial genomes [14, 15, 16, 17, 18], yet little is known about how this works. Previously, we established a Drosophila line transmitting two mitochondrial genomes in a stable ratio enforced by purifying selection benefiting one genome and a selfish advantage favoring the other [8]. Here, to find nuclear genes that impact mtDNA competition, we screened heterozygous deletions tiling ∼70% of the euchromatic regions and examined their influence on this ratio. This genome-wide screen detected many nuclear modifiers of this ratio and identified one as the catalytic subunit of mtDNA polymerase gene (POLG), tam. A reduced dose of tam drove elimination of defective mitochondrial genomes. This study suggests that our approach will uncover targets for interventions that would block propagation of pathogenic mitochondrial mutations. Multiple nuclear factors affect selective transmission of mitochondrial genomes Reducing mtDNA polymerase restricts the transmission of detrimental mtDNA mutants
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16
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Ali AT, Boehme L, Carbajosa G, Seitan VC, Small KS, Hodgkinson A. Nuclear genetic regulation of the human mitochondrial transcriptome. eLife 2019; 8:e41927. [PMID: 30775970 PMCID: PMC6420317 DOI: 10.7554/elife.41927] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 02/14/2019] [Indexed: 12/21/2022] Open
Abstract
Mitochondria play important roles in cellular processes and disease, yet little is known about how the transcriptional regime of the mitochondrial genome varies across individuals and tissues. By analyzing >11,000 RNA-sequencing libraries across 36 tissue/cell types, we find considerable variation in mitochondrial-encoded gene expression along the mitochondrial transcriptome, across tissues and between individuals, highlighting the importance of cell-type specific and post-transcriptional processes in shaping mitochondrial-encoded RNA levels. Using whole-genome genetic data we identify 64 nuclear loci associated with expression levels of 14 genes encoded in the mitochondrial genome, including missense variants within genes involved in mitochondrial function (TBRG4, MTPAP and LONP1), implicating genetic mechanisms that act in trans across the two genomes. We replicate ~21% of associations with independent tissue-matched datasets and find genetic variants linked to these nuclear loci that are associated with cardio-metabolic phenotypes and Vitiligo, supporting a potential role for variable mitochondrial-encoded gene expression in complex disease.
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Affiliation(s)
- Aminah T Ali
- Department of Medical and Molecular Genetics, School of Basic and Medical BiosciencesKing’s College LondonLondonUnited Kingdom
| | - Lena Boehme
- Department of Medical and Molecular Genetics, School of Basic and Medical BiosciencesKing’s College LondonLondonUnited Kingdom
| | - Guillermo Carbajosa
- Department of Medical and Molecular Genetics, School of Basic and Medical BiosciencesKing’s College LondonLondonUnited Kingdom
| | - Vlad C Seitan
- Department of Medical and Molecular Genetics, School of Basic and Medical BiosciencesKing’s College LondonLondonUnited Kingdom
| | - Kerrin S Small
- Department of Twin Research and Genetic Epidemiology, School of Life Course SciencesKing’s College LondonLondonUnited Kingdom
| | - Alan Hodgkinson
- Department of Medical and Molecular Genetics, School of Basic and Medical BiosciencesKing’s College LondonLondonUnited Kingdom
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17
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Serrano A, Asnani-Kishnani M, Rodríguez AM, Palou A, Ribot J, Bonet ML. Programming of the Beige Phenotype in White Adipose Tissue of Adult Mice by Mild Resveratrol and Nicotinamide Riboside Supplementations in Early Postnatal Life. Mol Nutr Food Res 2018; 62:e1800463. [PMID: 30095217 DOI: 10.1002/mnfr.201800463] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/31/2018] [Indexed: 12/31/2022]
Abstract
SCOPE Resveratrol (RSV) and nicotinamide riboside (NR) are food compounds with anti-obesity actions in adult rodents. Here, the long-term effects of RSV and NR mild supplementation throughout lactation on adiposity-related parameters and the appearance of the beige phenotype in white adipose tissue (WAT) in adulthood are assessed. METHODS AND RESULTS Newborn mice received orally RSV or NR from day 2 to 20 of life. Control littermates received the vehicle. All animals are weaned onto a chow diet on day 21. On day 90, half the animals of each group are assigned to a high-fat diet (HFD) for 10 weeks, while the other remained on a normal-fat diet. Energy-balance-related parameters, blood parameters, and gene expression and immunohistochemical analysis of WAT are assessed. Treated male mice show an improved response to the HFD, such as delayed body weight gain, a blunted increase in the plasma leptin/adiponectin ratio, and a decreased lipolytic response, together with signs of white-to-brown fat remodeling in inguinal WAT. These effects are absent in female mice. CONCLUSION RSV and NR supplementations in early postnatal life affect WAT's thermogenic/oxidative transcriptional phenotype and metabolic responses in adulthood, with upregulatory and beneficial effects evidenced in male animals.
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Affiliation(s)
- Alba Serrano
- Grup de Recerca Nutrigenòmica i Obesitat, Laboratori de Biologia Molecular, Nutrició i Biotecnologia (LBNB), Universitat de les Illes Balears, CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Madhu Asnani-Kishnani
- Grup de Recerca Nutrigenòmica i Obesitat, Laboratori de Biologia Molecular, Nutrició i Biotecnologia (LBNB), Universitat de les Illes Balears, CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Ana María Rodríguez
- Grup de Recerca Nutrigenòmica i Obesitat, Laboratori de Biologia Molecular, Nutrició i Biotecnologia (LBNB), Universitat de les Illes Balears, CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Andreu Palou
- Grup de Recerca Nutrigenòmica i Obesitat, Laboratori de Biologia Molecular, Nutrició i Biotecnologia (LBNB), Universitat de les Illes Balears, CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Joan Ribot
- Grup de Recerca Nutrigenòmica i Obesitat, Laboratori de Biologia Molecular, Nutrició i Biotecnologia (LBNB), Universitat de les Illes Balears, CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - María Luisa Bonet
- Grup de Recerca Nutrigenòmica i Obesitat, Laboratori de Biologia Molecular, Nutrició i Biotecnologia (LBNB), Universitat de les Illes Balears, CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma de Mallorca, Spain
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18
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Abstract
INTRODUCTION Pearson syndrome (PS) is a sporadic and very rare syndrome classically associated with single large-scale deletions of mitochondrial DNA and characterized by refractory sideroblastic anemia during infancy. Areas covered: This review presents an analysis and interpretation of the published data that forms the basis for our understanding of PS. PubMed, Google Scholarand Thompson ISI Web of Knowledge were searched for relevant data. Expert commentary: PS is a very rare mitochodrial disease that involves different organs and systems. Clinical phenotype is extremely variable and may change over the course of disease itself with the possibility both of worsenings and improvements. Outcome is invariably lethal and at the moment no cure is available. Accurate supportive treatment and follow up program in centres with experience in mitochondrial diseases and marrow failure may positively influence quality and duration of life.
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Affiliation(s)
- Piero Farruggia
- a Pediatric Hematology and Oncology Unit, Oncology Department , A.R.N.A.S. Ospedali Civico, Di Cristina e Benfratelli , Palermo , Italy
| | - Floriana Di Marco
- a Pediatric Hematology and Oncology Unit, Oncology Department , A.R.N.A.S. Ospedali Civico, Di Cristina e Benfratelli , Palermo , Italy
| | - Carlo Dufour
- b Clinical and Experimental Hematology Unit, G. Gaslini Children's Hospital , Genova , Italy
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19
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Hung KM, Chen PC, Hsieh HC, Calkins MJ. Mitochondrial defects arise from nucleoside/nucleotide reverse transcriptase inhibitors in neurons: Potential contribution to HIV-associated neurocognitive disorders. Biochim Biophys Acta Mol Basis Dis 2016; 1863:406-413. [PMID: 27840304 DOI: 10.1016/j.bbadis.2016.11.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/04/2016] [Accepted: 11/10/2016] [Indexed: 02/07/2023]
Abstract
The cornerstone of current HIV treatment is a class of drugs called nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs). However, patients who receive long term treatment with NRTIs often develop severe side effects, which are related to mitochondrial toxicity. The potential contribution of NRTI-mediated toxicity to HIV-associated neurocognitive disorders (HAND) has not been fully explored. NRTI toxicity is thought to be mediated through mitochondrial DNA polymerase γ (pol γ) inhibition, which impairs mitochondrial DNA (mtDNA) synthesis and leads to various mitochondrial dysfunctions. To evaluate the relationship between NRTI-mediated pol γ inhibition and mitochondrial toxicity in neurons, we systematically investigated mitochondrial regulation in NRTI-treated primary cortical neurons by measuring parameters related to mtDNA content, retrograde signaling responses and mitochondrial homeostasis. The effects of four different NRTIs with variable pol γ inhibitory activity and mitochondrial toxicity were assessed. The strong pol γ inhibitor, ddI, abolished mtDNA synthesis and greatly reduced mtDNA content. However, mtDNA transcription was not as severely affected, and no defects in oxidative phosphorylation were observed. Detrimental effects on mitochondrial respiration and motility were observed after AZT treatment in the absence of mtDNA depletion or inhibition of mtDNA synthesis. The results suggest that individual NRTIs, such as ddI and AZT, have the potential to cause mitochondrial toxicity in neurons. This mitochondrial toxicity would be expected to contribute to neurotoxicity in the central nervous system, and therefore, HAND etiology may be affected by NRTI treatment.
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Affiliation(s)
- Kui-Ming Hung
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan; Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan
| | - Pei-Chun Chen
- Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan
| | - Han-Chieh Hsieh
- Department of Neurology, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan
| | - Marcus J Calkins
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 704, Taiwan.
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20
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Reynés B, Serrano A, Petrov PD, Ribot J, Chetrit C, Martínez-Puig D, Bonet ML, Palou A. Anti-obesity and insulin-sensitising effects of a glycosaminoglycan mix. J Funct Foods 2016. [DOI: 10.1016/j.jff.2016.07.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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21
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Hung KM, Calkins MJ. Mitochondrial homeostatic disruptions are sensitive indicators of stress in neurons with defective mitochondrial DNA transactions. Mitochondrion 2016; 31:9-19. [PMID: 27581214 DOI: 10.1016/j.mito.2016.08.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/17/2016] [Accepted: 08/25/2016] [Indexed: 02/07/2023]
Abstract
Neurodegeneration and mitochondrial dysfunction are closely linked across many clinical conditions. In genetic diseases that result from defects in mitochondrial DNA (mtDNA) synthesis or maintenance, neurodegeneration is a frequent and major component of the disease pathology. In sporadic neurodegenerative diseases such as Alzheimer's and Parkinson's disease, mtDNA defects have been observed clinically. Mitochondrial stress related to mtDNA dysregulation can produce neuronal dysfunction and death via impaired electron transport chain activity, which results in deficient ATP production and related increases in mitochondrial reactive oxygen species (ROS) production. However, mtDNA dysregulation in post-mitotic neurons may also produce disturbances in mitochondrial homeostasis that are known to impair neuronal function as well. In this study, we used sub-toxic doses of ethidium bromide (EtBr) to induce mtDNA-associated mitochondrial stress in primary cortical neurons and measured several aspects of mitochondrial homeostasis, mitochondrial function and cell death. We found that low-dose EtBr severely depletes mtDNA synthesis and mitochondrial mRNA levels. Furthermore, homeostatic processes are especially disrupted in toxin treated neurons while mitochondrial function is relatively preserved. Mitochondria become fragmented and motility is abolished, while respiration and mitochondrial polarization are partially maintained. Moreover at these doses, cells do not exhibit increased ROS production, clear neurite retraction or loss of viability. These results indicate that mitochondrial homeostasis is a sensitive marker of mtDNA associated stress compared to mitochondria-functional outputs or endpoints related to cellular toxicity. These homeostatic disruptions are expected to contribute to neuronal dysfunction and potentially drive neurodegenerative disease pathology.
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Affiliation(s)
- Kui-Ming Hung
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Marcus J Calkins
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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22
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Souren NYP, Gerdes LA, Kümpfel T, Lutsik P, Klopstock T, Hohlfeld R, Walter J. Mitochondrial DNA Variation and Heteroplasmy in Monozygotic Twins Clinically Discordant for Multiple Sclerosis. Hum Mutat 2016; 37:765-75. [PMID: 27119776 DOI: 10.1002/humu.23003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 04/10/2016] [Indexed: 12/22/2022]
Abstract
We examined the debated link between mitochondrial DNA (mtDNA) variation and multiple sclerosis (MS) using 49 monozygotic (MZ) twin pairs clinically discordant for MS, which enables to associate de novo mtDNA variants, skewed heteroplasmy, and mtDNA copy number with MS manifestation. Ultra-deep sequencing of blood-derived mtDNA revealed 25 heteroplasmic variants with potentially pathogenic features in 18 pairs. All variants were pair-specific and had low and/or similar heteroplasmy levels in both cotwins. In one pair, a confirmed pathogenic variant (m.11778G>A, heteroplasmy ∼50%) associated with Leber hereditary optic neuropathy was detected. Detailed diagnostic investigation revealed subclinical MS signs in the prior nondiseased cotwin. Moreover, neither mtDNA deletions nor copy-number variations were involved. Furthermore, the majority of heteroplasmic variants were shared among MZ twins and exhibited more similar heteroplasmy levels in the same tissue of MZ twins as compared with different tissues of the same individual. Heteroplasmy levels were also more similar within MZ twins compared with nonidentical siblings. Our analysis excludes mtDNA variation as a major driver of the discordant clinical manifestation of MS in MZ twins, and provides valuable insights into the occurrence and distribution of heteroplasmic variants within MZ twins and nonidentical siblings, and across different tissues.
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Affiliation(s)
- Nicole Y P Souren
- Department of Genetics/Epigenetics, Saarland University, Saarbrücken, Germany
| | - Lisa A Gerdes
- Institute of Clinical Neuroimmunology, Medical Campus Großhadern, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Tania Kümpfel
- Institute of Clinical Neuroimmunology, Medical Campus Großhadern, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Pavlo Lutsik
- Department of Genetics/Epigenetics, Saarland University, Saarbrücken, Germany
| | - Thomas Klopstock
- Department of Neurology, Friedrich-Baur-Institute, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.,DZNE - German Center for Neurodegenerative Diseases, Munich, Germany
| | - Reinhard Hohlfeld
- Institute of Clinical Neuroimmunology, Medical Campus Großhadern, Ludwig-Maximilians-Universität München, Munich, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Jörn Walter
- Department of Genetics/Epigenetics, Saarland University, Saarbrücken, Germany
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23
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Petrov PD, Palou A, Bonet ML, Ribot J. Cell-Autonomous Brown-Like Adipogenesis of Preadipocytes From Retinoblastoma Haploinsufficient Mice. J Cell Physiol 2016; 231:1941-52. [PMID: 26727985 DOI: 10.1002/jcp.25299] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 01/04/2016] [Indexed: 12/20/2022]
Abstract
Mechanisms behind the emergence of brown adipocyte-like (brite or beige) adipocytes within white adipose tissue (WAT) are of interest. Retinoblastoma protein gene (Rb) haploinsufficiency associates in mice with improved metabolic regulation linked to a greater capacity for fatty acid oxidation and thermogenesis in WAT. We aimed to explain a feasible mechanism of WAT-to-BAT remodeling in this model. Differentiated primary adipocytes and Sca1-positive preadipocytes derived from adipose depots of Rb(+/-) mice and wild-type siblings were compared. Primary white Rb(+/-) adipocytes displayed under basal conditions increased glucose uptake and an enhanced expression of brown adipocyte-related genes (Pparg, Ppargc1a, Ppargc1b, Prdm16, Cpt1b) but not of purported beige/brite transcriptional markers (Cd137, Tmem26, Tbx1, Slc27a1, Hoxc9, Shox2). Lack of induction of beige markers phenocopied results in WAT of adult Rb(+/-) mice. Flow cytometry analysis evidenced an increased number of preadipocytes in WAT depots of Rb(+/-) mice. Sca1(+) preadipocytes from WAT of Rb(+/-) mice displayed increased gene expression of several transcription factors common to the brown and beige adipogenic programs (Prdm16, Pparg, Ppargc1a) and of receptors of bone morphogenetic proteins (BMPs); however, among the recently proposed beige markers, only Tbx1 was upregulated. Adult Rb(+/-) mice had increased circulating levels of BMP7. These results indicate that preadipose cells resident in WAT depots of Rb(+/-) mice retain an increased capacity for brown-like adipogenesis that appears to be different from beige adipogenesis, and suggest that the contribution of these precursors to the Rb(+/-) adipose phenotype is driven, at least in part, by interaction with BMP7 pathways. J. Cell. Physiol. 231: 1941-1952, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Petar D Petrov
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca, CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain
| | - Andreu Palou
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca, CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain
| | - M Luisa Bonet
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca, CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain
| | - Joan Ribot
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca, CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Spain
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24
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Jokinen R, Marttinen P, Stewart JB, Neil Dear T, Battersby BJ. Tissue-specific modulation of mitochondrial DNA segregation by a defect in mitochondrial division. Hum Mol Genet 2015; 25:706-14. [PMID: 26681804 DOI: 10.1093/hmg/ddv508] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 12/08/2015] [Indexed: 01/19/2023] Open
Abstract
Mitochondria are dynamic organelles that divide and fuse by remodeling an outer and inner membrane in response to developmental, physiological and stress stimuli. These events are coordinated by conserved dynamin-related GTPases. The dynamics of mitochondrial morphology require coordination with mitochondrial DNA (mtDNA) to ensure faithful genome transmission, however, this process remains poorly understood. Mitochondrial division is linked to the segregation of mtDNA but how it affects cases of mtDNA heteroplasmy, where two or more mtDNA variants/mutations co-exist in a cell, is unknown. Segregation of heteroplasmic human pathogenic mtDNA mutations is a critical factor in the onset and severity of human mitochondrial diseases. Here, we investigated the coupling of mitochondrial morphology to the transmission and segregation of mtDNA in mammals by taking advantage of two genetically modified mouse models: one with a dominant-negative mutation in the dynamin-related protein 1 (Drp1 or Dnm1l) that impairs mitochondrial fission and the other, heteroplasmic mice segregating two neutral mtDNA haplotypes (BALB and NZB). We show a tissue-specific response to mtDNA segregation from a defect in mitochondrial fission. Only mtDNA segregation in the hematopoietic compartment is modulated from impaired Dnm1l function. In contrast, no effect was observed in other tissues arising from the three germ layers during development and in mtDNA transmission through the female germline. Our data suggest a robust organization of a heteroplasmic mtDNA segregating unit across mammalian cell types that can overcome impaired mitochondrial division to ensure faithful transmission of the mitochondrial genome.
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Affiliation(s)
- Riikka Jokinen
- Research Programs Unit - Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - Paula Marttinen
- Research Programs Unit - Molecular Neurology, University of Helsinki, Helsinki, Finland
| | - James B Stewart
- Max Planck Institute for Biology of Ageing, Cologne, Germany and
| | - T Neil Dear
- South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Brendan J Battersby
- Research Programs Unit - Molecular Neurology, University of Helsinki, Helsinki, Finland,
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25
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Petrov PD, Ribot J, López-Mejía IC, Fajas L, Palou A, Bonet ML. Retinoblastoma Protein Knockdown Favors Oxidative Metabolism and Glucose and Fatty Acid Disposal in Muscle Cells. J Cell Physiol 2015; 231:708-18. [DOI: 10.1002/jcp.25121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 07/31/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Petar D. Petrov
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
| | - Joan Ribot
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
| | | | - Lluís Fajas
- Department of Physiology; Université de Lausanne; Switzerland
| | - Andreu Palou
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
| | - M. Luisa Bonet
- Laboratory of Molecular Biology, Nutrition and Biotechnology-Nutrigenomics, Universitat de les Illes Balears, Palma de Mallorca; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); Spain
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26
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Stewart JB, Chinnery PF. The dynamics of mitochondrial DNA heteroplasmy: implications for human health and disease. Nat Rev Genet 2015; 16:530-42. [PMID: 26281784 DOI: 10.1038/nrg3966] [Citation(s) in RCA: 564] [Impact Index Per Article: 62.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Common genetic variants of mitochondrial DNA (mtDNA) increase the risk of developing several of the major health issues facing the western world, including neurodegenerative diseases. In this Review, we consider how these mtDNA variants arose and how they spread from their origin on one single molecule in a single cell to be present at high levels throughout a specific organ and, ultimately, to contribute to the population risk of common age-related disorders. mtDNA persists in all aerobic eukaryotes, despite a high substitution rate, clonal propagation and little evidence of recombination. Recent studies have found that de novo mtDNA mutations are suppressed in the female germ line; despite this, mtDNA heteroplasmy is remarkably common. The demonstration of a mammalian mtDNA genetic bottleneck explains how new germline variants can increase to high levels within a generation, and the ultimate fixation of less-severe mutations that escape germline selection explains how they can contribute to the risk of late-onset disorders.
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Affiliation(s)
- James B Stewart
- Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
| | - Patrick F Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 1BZ, UK
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27
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Lombès A, Auré K, Jardel C. [Pathophysiology of human mitochondrial diseases]. Biol Aujourdhui 2015; 209:125-132. [PMID: 26514381 DOI: 10.1051/jbio/2015014] [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: 12/18/2014] [Indexed: 06/05/2023]
Abstract
Mitochondrial diseases, defined as the diseases due to oxidative phosphorylation defects, are the most frequent inborn errors of metabolism. Their clinical presentation is highly diverse. Their diagnosis is difficult. It relies on metabolic parameters, histological anomalies and enzymatic assays showing defective activity, all of which are both inconstant and relatively unspecific. Most mitochondrial diseases have a genetic origin. Candidate genes are very numerous, located either in the mitochondrial genome or the nuclear DNA. Pathophysiological mechanisms of mitochondrial diseases are still the matter of much debate. Those underlying the tissue-specificity of diseases due to the alterations of a ubiquitously expressed gene are discussed including (i) quantitative aspect of the expression of the causal gene or its partners when appropriate, (ii) quantitative aspects of the bioenergetic function in each tissue, and (iii) tissue distribution of heteroplasmic mitochondrial DNA alterations.
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Affiliation(s)
- Anne Lombès
- Inserm U1016,CNRS UMR 8104, Institut Cochin, 24 rue du Faubourg Saint Jacques, 75014 Paris, France - Université Paris-Descartes-Paris 5, 75014 Paris, France
| | - Karine Auré
- Inserm U1016,CNRS UMR 8104, Institut Cochin, 24 rue du Faubourg Saint Jacques, 75014 Paris, France - AP-HP, Hôpital Ambroise Paré, Service d'Explorations Fonctionnelles, 92100 Boulogne-Billancourt, France - Université Versailles-Saint-Quentin en Yvelines, 78180 Montigny-Le-Bretonneux, France
| | - Claude Jardel
- Inserm U1016,CNRS UMR 8104, Institut Cochin, 24 rue du Faubourg Saint Jacques, 75014 Paris, France - AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, CHU Pitié-Salpêtrière, 75651 Paris, France
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28
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Machado TS, Macabelli CH, Sangalli JR, Rodrigues TB, Smith LC, Meirelles FV, Chiaratti MR. Real-Time PCR Quantification of Heteroplasmy in a Mouse Model with Mitochondrial DNA of C57BL/6 and NZB/BINJ Strains. PLoS One 2015; 10:e0133650. [PMID: 26274500 PMCID: PMC4537288 DOI: 10.1371/journal.pone.0133650] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/30/2015] [Indexed: 11/18/2022] Open
Abstract
Mouse models are widely employed to study mitochondrial inheritance, which have implications to several human diseases caused by mutations in the mitochondrial genome (mtDNA). These mouse models take advantage of polymorphisms between the mtDNA of the NZB/BINJ and the mtDNA of common inbred laboratory (i.e., C57BL/6) strains to generate mice with two mtDNA haplotypes (heteroplasmy). Based on PCR followed by restriction fragment length polymorphism (PCR-RFLP), these studies determine the level of heteroplasmy across generations and in different cell types aiming to understand the mechanisms underlying mitochondrial inheritance. However, PCR-RFLP is a time-consuming method of low sensitivity and accuracy that dependents on the use of restriction enzyme digestions. A more robust method to measure heteroplasmy has been provided by the use of real-time quantitative PCR (qPCR) based on allelic refractory mutation detection system (ARMS-qPCR). Herein, we report an ARMS-qPCR assay for quantification of heteroplasmy using heteroplasmic mice with mtDNA of NZB/BINJ and C57BL/6 origin. Heteroplasmy and mtDNA copy number were estimated in germline and somatic tissues, providing evidence of the reliability of the approach. Furthermore, it enabled single-step quantification of heteroplasmy, with sensitivity to detect as low as 0.1% of either NZB/BINJ or C57BL/6 mtDNA. These findings are relevant as the ARMS-qPCR assay reported here is fully compatible with similar heteroplasmic mouse models used to study mitochondrial inheritance in mammals.
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Affiliation(s)
- Thiago Simões Machado
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, SP, 13565–905, Brazil
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508–270, Brazil
- Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, SP, 13635–900, Brazil
| | - Carolina Habermann Macabelli
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, SP, 13565–905, Brazil
- Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, SP, 13635–900, Brazil
| | - Juliano Rodrigues Sangalli
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508–270, Brazil
- Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, SP, 13635–900, Brazil
| | - Thiago Bittencourt Rodrigues
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, SP, 13565–905, Brazil
| | - Lawrence Charles Smith
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508–270, Brazil
- Centre de recherche en reproduction animale, Faculté de Medecine Vétérinaire, Université de Montréal, Saint Hyacinthe, QC, J2S 7C6, Canada
| | - Flávio Vieira Meirelles
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508–270, Brazil
- Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, SP, 13635–900, Brazil
| | - Marcos Roberto Chiaratti
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, SP, 13565–905, Brazil
- Departamento de Cirurgia, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, 05508–270, Brazil
- Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga, SP, 13635–900, Brazil
- * E-mail:
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29
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Pyle A, Hudson G, Wilson IJ, Coxhead J, Smertenko T, Herbert M, Santibanez-Koref M, Chinnery PF. Extreme-Depth Re-sequencing of Mitochondrial DNA Finds No Evidence of Paternal Transmission in Humans. PLoS Genet 2015; 11:e1005040. [PMID: 25973765 PMCID: PMC4431825 DOI: 10.1371/journal.pgen.1005040] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 01/28/2015] [Indexed: 11/18/2022] Open
Abstract
Recent reports have questioned the accepted dogma that mammalian mitochondrial DNA (mtDNA) is strictly maternally inherited. In humans, the argument hinges on detecting a signature of inter-molecular recombination in mtDNA sequences sampled at the population level, inferring a paternal source for the mixed haplotypes. However, interpreting these data is fraught with difficulty, and direct experimental evidence is lacking. Using extreme-high depth mtDNA re-sequencing up to ~1.2 million-fold coverage, we find no evidence that paternal mtDNA haplotypes are transmitted to offspring in humans, thus excluding a simple dilution mechanism for uniparental transmission of mtDNA present in all healthy individuals. Our findings indicate that an active mechanism eliminates paternal mtDNA which likely acts at the molecular level. Emerging evidence raises the possibility that human mitochondrial DNA (mtDNA) is not strictly maternally inherited, but it has not been technically possible to test this hypothesis directly. We identified trios with discordant mtDNA haplotypes, parent-offspring trios were validated using polymorphic microsatellites, and then used extreme-high depth mtDNA re-sequencing to look for paternally transmitted mtDNA. Despite having up to ~1.2 million-fold coverage of mtDNA, we find no evidence that paternal mtDNA haplotypes are transmitted to offspring in humans. Our findings exclude a simple dilution mechanism for uniparental transmission of mtDNA present in all healthy individuals.
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Affiliation(s)
- Angela Pyle
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Gavin Hudson
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Ian J. Wilson
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Jonathan Coxhead
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Tania Smertenko
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Mary Herbert
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Mauro Santibanez-Koref
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Patrick F. Chinnery
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
- * E-mail:
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30
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Quantitative changes in Gimap3 and Gimap5 expression modify mitochondrial DNA segregation in mice. Genetics 2015; 200:221-35. [PMID: 25808953 DOI: 10.1534/genetics.115.175596] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 03/20/2015] [Indexed: 01/22/2023] Open
Abstract
Mammalian mitochondrial DNA (mtDNA) is a high-copy maternally inherited genome essential for aerobic energy metabolism. Mutations in mtDNA can lead to heteroplasmy, the co-occurence of two different mtDNA variants in the same cell, which can segregate in a tissue-specific manner affecting the onset and severity of mitochondrial dysfunction. To investigate mechanisms regulating mtDNA segregation we use a heteroplasmic mouse model with two polymorphic neutral mtDNA haplotypes (NZB and BALB) that displays tissue-specific and age-dependent selection for mtDNA haplotypes. In the hematopoietic compartment there is selection for the BALB mtDNA haplotype, a phenotype that can be modified by allelic variants of Gimap3. Gimap3 is a tail-anchored member of the GTPase of the immunity-associated protein (Gimap) family of protein scaffolds important for leukocyte development and survival. Here we show how the expression of two murine Gimap3 alleles from Mus musculus domesticus and M. m. castaneus differentially affect mtDNA segregation. The castaneus allele has incorporated a uORF (upstream open reading frame) in-frame with the Gimap3 mRNA that impairs translation and imparts a negative effect on the steady-state protein abundance. We found that quantitative changes in the expression of Gimap3 and the paralogue Gimap5, which encodes a lysosomal protein, affect mtDNA segregation in the mouse hematopoietic tissues. We also show that Gimap3 localizes to the endoplasmic reticulum and not mitochondria as previously reported. Collectively these data show that the abundance of protein scaffolds on the endoplasmic reticulum and lysosomes are important to the segregation of the mitochondrial genome in the mouse hematopoietic compartment.
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31
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Burgstaller JP, Johnston IG, Poulton J. Mitochondrial DNA disease and developmental implications for reproductive strategies. Mol Hum Reprod 2014; 21:11-22. [PMID: 25425607 PMCID: PMC4275042 DOI: 10.1093/molehr/gau090] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial diseases are potentially severe, incurable diseases resulting from dysfunctional mitochondria. Several important mitochondrial diseases are caused by mutations in mitochondrial DNA (mtDNA), the genetic material contained within mitochondria, which is maternally inherited. Classical and modern therapeutic approaches exist to address the inheritance of mtDNA disease, but are potentially complicated by the fact that cellular mtDNA populations evolve according to poorly-understood dynamics during development and organismal lifetimes. We review these therapeutic approaches and models of mtDNA dynamics during development, and discuss the implications of recent results from these models for modern mtDNA therapies. We particularly highlight mtDNA segregation—differences in proliferative rates between different mtDNA haplotypes—as a potential and underexplored issue in such therapies. However, straightforward strategies exist to combat this and other potential therapeutic problems. In particular, we describe haplotype matching as an approach with the power to potentially ameliorate any expected issues from mtDNA incompatibility.
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Affiliation(s)
- Joerg Patrick Burgstaller
- Biotechnology in Animal Production, Department for Agrobiotechnology, IFA Tulln, 3430 Tulln, Austria Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Iain G Johnston
- Department of Mathematics, Imperial College London, London SW7 2AZ, UK
| | - Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford OX3 9DU, UK
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32
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Jokinen R, Junnila H, Battersby BJ. Gimap3: A foot-in-the-door to tissue-specific regulation of mitochondrial DNA genetics. Small GTPases 2014; 2:31-35. [PMID: 21686279 DOI: 10.4161/sgtp.2.1.14937] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/18/2011] [Accepted: 01/23/2011] [Indexed: 01/31/2023] Open
Abstract
Mitochondrial DNA (mtDNA) is a multi-copy genome encoding for proteins essential for aerobic energy metabolism. Mutations in mtDNA can lead to a variety of human diseases, from mild metabolic syndromes to severe fatal encephalomyopathies. Most mtDNA mutations co-exist with wild type genomes in a state known as heteroplasmy. The segregation of these pathogenic mutants is tissue and mutation specific, and a key determinant in the onset and severity of human mitochondrial disorders. We used a forward genetic approach in mice to identify and demonstrate that Gimap3 (GTP ase of immunity associated protein) is a key regulator of mtDNA segregation in leukocytes. The Gimap gene cluster is found only in vertebrates and appear to be a class of nucleotide-dependent dimerization GTP ases. Gimap3 is a membrane-anchored GTP ase with a critical role in T cell development. Here, we summarize our genetic findings and postulate how Gimap3 might regulate mtDNA genetics.
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Affiliation(s)
- Riikka Jokinen
- Research Program of Molecular Neurology and Institute of Biomedicine; Biomedicum Helsinki; University of Helsinki; Helsinki, Finland
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33
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Webb LMC, Pascall JC, Hepburn L, Carter C, Turner M, Butcher GW. Generation and characterisation of mice deficient in the multi-GTPase domain containing protein, GIMAP8. PLoS One 2014; 9:e110294. [PMID: 25329815 PMCID: PMC4201521 DOI: 10.1371/journal.pone.0110294] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/17/2014] [Indexed: 02/06/2023] Open
Abstract
Background GTPases of the immunity-associated protein family (GIMAPs) are predominantly expressed in mature lymphocytes. Studies of rodents deficient in GIMAP1, GIMAP4, or GIMAP5 have demonstrated that these GTPases regulate lymphocyte survival. In contrast to the other family members, GIMAP8 contains three potential GTP-binding domains (G-domains), a highly unusual feature suggesting a novel function for this protein. To examine a role for GIMAP8 in lymphocyte biology we examined GIMAP8 expression during lymphocyte development. We also generated a mouse deficient in GIMAP8 and examined lymphocyte development and function. Principal Findings We show that GIMAP8 is expressed in the very early and late stages of T cell development in the thymus, at late stages during B cell development, and peripheral T and B cells. We find no defects in T or B lymphocyte development in the absence of GIMAP8. A marginal decrease in the number of recirculating bone marrow B cells suggests that GIMAP8 is important for the survival of mature B cells within the bone marrow niche. We also show that deletion of GIMAP8 results in a delay in apoptotic death of mature T cell in vitro in response to dexamethasone or γ-irradiation. However, despite these findings we find that GIMAP8-deficient mice mount normal primary and secondary responses to a T cell dependent antigen. Conclusions Despite its unique structure, GIMAP8 is not required for lymphocyte development but appears to have a minor role in maintaining recirculating B cells in the bone marrow niche and a role in regulating apoptosis of mature T cells.
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Affiliation(s)
- Louise M. C. Webb
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
- * E-mail:
| | - John C. Pascall
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Lucy Hepburn
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Christine Carter
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Martin Turner
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Geoffrey W. Butcher
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
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34
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Tubulin- and actin-associating GIMAP4 is required for IFN-γ secretion during Th cell differentiation. Immunol Cell Biol 2014; 93:158-66. [PMID: 25287446 PMCID: PMC4355353 DOI: 10.1038/icb.2014.86] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 09/05/2014] [Accepted: 09/06/2014] [Indexed: 12/20/2022]
Abstract
Although GTPase of the immunity-associated protein (GIMAP) family are known to be most highly expressed in the cells of the immune system, their function and role remain still poorly characterized. Small GTPases in general are known to be involved in many cellular processes in a cell type-specific manner and to contribute to specific differentiation processes. Among GIMAP family, GIMAP4 is the only member reported to have true GTPase activity, and its transcription is found to be differentially regulated during early human CD4(+) T helper (Th) lymphocyte differentiation. GIMAP4 has been previously connected mainly with T- and B-cell development and survival and T-cell apoptosis. Here we show GIMAP4 to be localized into cytoskeletal elements and with the component of the trans golgi network, which suggests it to have a function in cellular transport processes. We demonstrate that depletion of GIMAP4 with RNAi results in downregulation of endoplasmic reticulum localizing chaperone VMA21. Most importantly, we discovered that GIMAP4 regulates secretion of cytokines in early differentiating human CD4(+) Th lymphocytes and in particular the secretion of interferon-γ also affecting its downstream targets.
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35
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Burgstaller JP, Johnston IG, Jones NS, Albrechtová J, Kolbe T, Vogl C, Futschik A, Mayrhofer C, Klein D, Sabitzer S, Blattner M, Gülly C, Poulton J, Rülicke T, Piálek J, Steinborn R, Brem G. MtDNA segregation in heteroplasmic tissues is common in vivo and modulated by haplotype differences and developmental stage. Cell Rep 2014; 7:2031-2041. [PMID: 24910436 DOI: 10.1016/j.celrep.2014.05.020] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 03/11/2014] [Accepted: 05/12/2014] [Indexed: 12/21/2022] Open
Abstract
The dynamics by which mitochondrial DNA (mtDNA) evolves within organisms are still poorly understood, despite the fact that inheritance and proliferation of mutated mtDNA cause fatal and incurable diseases. When two mtDNA haplotypes are present in a cell, it is usually assumed that segregation (the proliferation of one haplotype over another) is negligible. We challenge this assumption by showing that segregation depends on the genetic distance between haplotypes. We provide evidence by creating four mouse models containing mtDNA haplotype pairs of varying diversity. We find tissue-specific segregation in all models over a wide range of tissues. Key findings are segregation in postmitotic tissues (important for disease models) and segregation covering all developmental stages from prenatal to old age. We identify four dynamic regimes of mtDNA segregation. Our findings suggest potential complications for therapies in human populations: we propose "haplotype matching" as an approach to avoid these issues.
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Affiliation(s)
- Joerg Patrick Burgstaller
- Biotechnology in Animal Production, Department for Agrobiotechnology, IFA Tulln, 3430 Tulln, Austria.,Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Iain G Johnston
- Department of Mathematics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Nick S Jones
- Department of Mathematics, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jana Albrechtová
- Research Facility Studenec, Academy of Sciences of the Czech Republic, Květná 8, 60365 Brno, Czech Republic
| | - Thomas Kolbe
- Biomodels Austria, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.,Department for Agrobiotechnology, IFA Tulln, University of Natural Resources and Applied Life Sciences, Tulln 3430, Austria
| | - Claus Vogl
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Andreas Futschik
- Department of Statistics, University of Vienna, 1010 Vienna, Austria
| | - Corina Mayrhofer
- Biotechnology in Animal Production, Department for Agrobiotechnology, IFA Tulln, 3430 Tulln, Austria.,Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Dieter Klein
- VetCore Facility for Research, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Sonja Sabitzer
- VetCore Facility for Research, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Mirjam Blattner
- VetCore Facility for Research, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Christian Gülly
- Center for Medical Research, Medical University of Graz, 8010 Graz, Austria
| | - Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford OX3 9DU, United Kingdom
| | - Thomas Rülicke
- Institute of Laboratory Animal Science, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Jaroslav Piálek
- Research Facility Studenec, Academy of Sciences of the Czech Republic, Květná 8, 60365 Brno, Czech Republic
| | - Ralf Steinborn
- VetCore Facility for Research, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Gottfried Brem
- Biotechnology in Animal Production, Department for Agrobiotechnology, IFA Tulln, 3430 Tulln, Austria.,Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
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36
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Folmes CDL, Martinez-Fernandez A, Perales-Clemente E, Li X, McDonald A, Oglesbee D, Hrstka SC, Perez-Terzic C, Terzic A, Nelson TJ. Disease-causing mitochondrial heteroplasmy segregated within induced pluripotent stem cell clones derived from a patient with MELAS. Stem Cells 2014; 31:1298-308. [PMID: 23553816 DOI: 10.1002/stem.1389] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 03/06/2013] [Indexed: 01/19/2023]
Abstract
Mitochondrial diseases display pathological phenotypes according to the mixture of mutant versus wild-type mitochondrial DNA (mtDNA), known as heteroplasmy. We herein examined the impact of nuclear reprogramming and clonal isolation of induced pluripotent stem cells (iPSC) on mitochondrial heteroplasmy. Patient-derived dermal fibroblasts with a prototypical mitochondrial deficiency diagnosed as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) demonstrated mitochondrial dysfunction with reduced oxidative reserve due to heteroplasmy at position G13513A in the ND5 subunit of complex I. Bioengineered iPSC clones acquired pluripotency with multilineage differentiation capacity and demonstrated reduction in mitochondrial density and oxygen consumption distinguishing them from the somatic source. Consistent with the cellular mosaicism of the original patient-derived fibroblasts, the MELAS-iPSC clones contained a similar range of mtDNA heteroplasmy of the disease-causing mutation with identical profiles in the remaining mtDNA. High-heteroplasmy iPSC clones were used to demonstrate that extended stem cell passaging was sufficient to purge mutant mtDNA, resulting in isogenic iPSC subclones with various degrees of disease-causing genotypes. On comparative differentiation of iPSC clones, improved cardiogenic yield was associated with iPSC clones containing lower heteroplasmy compared with isogenic clones with high heteroplasmy. Thus, mtDNA heteroplasmic segregation within patient-derived stem cell lines enables direct comparison of genotype/phenotype relationships in progenitor cells and lineage-restricted progeny, and indicates that cell fate decisions are regulated as a function of mtDNA mutation load. The novel nuclear reprogramming-based model system introduces a disease-in-a-dish tool to examine the impact of mutant genotypes for MELAS patients in bioengineered tissues and a cellular probe for molecular features of individual mitochondrial diseases.
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37
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Ciucci T, Bosselut R. Gimap and T cells: a matter of life or death. Eur J Immunol 2014; 44:348-51. [PMID: 24510500 DOI: 10.1002/eji.201344375] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Revised: 12/29/2013] [Accepted: 01/13/2014] [Indexed: 11/08/2022]
Abstract
GTPase immune-associated proteins (Gimap) genes encode evolutionarily conserved GTP-binding proteins that are preferentially expressed in immune cells. Specific members have been shown to be involved in lymphocyte development, or are associated with inflammatory and autoimmune diseases. However, the function of these proteins remains poorly understood, both at the cellular and molecular levels. A new study in this issue of the European Journal of Immunology [Eur. J. Immunol. 2014. 44: 561-572] points to the distinct but partly overlapping functions of two members of this family, Gimap3 and Gimap5, and offers new insight into their potential functions in T cells.
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Affiliation(s)
- Thomas Ciucci
- Laboratory of Immune Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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38
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Spyropoulos A, Manford M, Horvath R, Alston CL, Yu-Wai-Man P, He L, Taylor RW, Chinnery PF. Near-identical segregation of mtDNA heteroplasmy in blood, muscle, urinary epithelium, and hair follicles in twins with optic atrophy, ptosis, and intractable epilepsy. JAMA Neurol 2014; 70:1552-5. [PMID: 24126373 DOI: 10.1001/jamaneurol.2013.4111] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Mitochondrial DNA (mtDNA) disorders have emerged as major causes of inherited neurologic disease. Despite being well recognized for more than 2 decades, the clinical presentation continues to broaden. The phenotypic heterogeneity is partly owing to different percentage levels of mutant mtDNA heteroplasmy in different tissues, but the factors influencing this are poorly understood. OBSERVATIONS This case report describes monozygotic male twins with ptosis, optic atrophy, and recent-onset intractable myoclonic epilepsy. The assessment of respiratory chain enzyme activities in the muscle from 1 twin revealed a severe and isolated defect involving mitochondrial complex I. Mitochondrial DNA sequencing revealed a pathogenic m.14487T>C MTND6 mutation, which was present at very high levels of heteroplasmy in muscle (84%) and lower levels in blood (15%), urinary epithelium (75%), and buccal mucosa (58%). Of particular interest, his identical twin was found to harbor very similar levels of the m.14487T>C mutation in his blood, urine, buccal mucosa, and hair follicle DNA samples, while the presence of low levels in the mother's tissues confirmed maternal transmission. CONCLUSIONS AND RELEVANCE It was shown that m14487T>C can also cause the unusual combination of optic atrophy, ptosis, and encephalomyopathy leading to intractable seizures. Near-identical heteroplasmy levels in different tissues in both siblings support a nuclear genetic mechanism controlling the tissue segregation of mtDNA mutations.
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Affiliation(s)
- Achilles Spyropoulos
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, England
| | - Mark Manford
- Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, England
| | - Rita Horvath
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, England
| | - Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Institute of Ageing and Health, Newcastle University, Newcastle Upon Tyne, England
| | - Patrick Yu-Wai-Man
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, England
| | - Langping He
- Wellcome Centre for Mitochondrial Research, Institute of Ageing and Health, Newcastle University, Newcastle Upon Tyne, England
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Institute of Ageing and Health, Newcastle University, Newcastle Upon Tyne, England
| | - Patrick F Chinnery
- Wellcome Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, England
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Wallace DC, Chalkia D. Mitochondrial DNA genetics and the heteroplasmy conundrum in evolution and disease. Cold Spring Harb Perspect Biol 2013; 5:a021220. [PMID: 24186072 PMCID: PMC3809581 DOI: 10.1101/cshperspect.a021220] [Citation(s) in RCA: 441] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The unorthodox genetics of the mtDNA is providing new perspectives on the etiology of the common "complex" diseases. The maternally inherited mtDNA codes for essential energy genes, is present in thousands of copies per cell, and has a very high mutation rate. New mtDNA mutations arise among thousands of other mtDNAs. The mechanisms by which these "heteroplasmic" mtDNA mutations come to predominate in the female germline and somatic tissues is poorly understood, but essential for understanding the clinical variability of a range of diseases. Maternal inheritance and heteroplasmy also pose major challengers for the diagnosis and prevention of mtDNA disease.
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Affiliation(s)
- Douglas C Wallace
- Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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40
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St John J. The control of mtDNA replication during differentiation and development. Biochim Biophys Acta Gen Subj 2013; 1840:1345-54. [PMID: 24183916 DOI: 10.1016/j.bbagen.2013.10.036] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 12/01/2022]
Abstract
BACKGROUND Mitochondrial DNA (mtDNA) is important for energy production as it encodes some of the key genes of electron transfer chain, where the majority of cellular energy is generated through oxidative phosphorylation (OXPHOS). MtDNA replication is mediated by nuclear DNA-encoded proteins or enzymes, which translocate to the mitochondria, and is strictly regulated throughout development. It starts with approximately 200 copies in each primordial germ cell and these copies undergo expansion and restriction events at various stages of development. SCOPE OF REVIEW I describe the patterns of mtDNA replication at key stages of development. I explain that it is essential to regulate mtDNA copy number and to establish the mtDNA set point in order that the mature, specialised cell acquires the appropriate numbers of mtDNA copy to generate sufficient adenosine triphosphate (ATP) through OXPHOS to undertake its specialised function. I discuss how these processes are dependent on the controlled expression of the nuclear-encoded mtDNA-specific replication factors and that this can be modulated by mtDNA haplotypes. I discuss how these events are altered by certain assisted reproductive technologies, some of which have been proposed to prevent the transmission of mutant mtDNA and others to overcome infertility. Furthermore, some of these technologies are predisposed to transmitting two or more populations of mtDNA, which can be extremely harmful. MAJOR CONCLUSIONS The failure to regulate mtDNA replication and mtDNA transmission during development is disadvantageous. GENERAL SIGNIFICANCE Manipulation of oocytes and embryos can lead to significant implications for the maternal-only transmission of mtDNA. This article is part of a Special Issue entitled Frontiers of mitochondrial research.
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Affiliation(s)
- Justin St John
- Mitochondrial Genetics Group, Centre for Genetic Diseases, Monash Institute of Medical Research, Monash University, 27-31 Wright Street, Clayton, Victoria 3168, Australia.
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41
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Yano K, Carter C, Yoshida N, Abe T, Yamada A, Nitta T, Ishimaru N, Takada K, Butcher GW, Takahama Y. Gimap3 and Gimap5 cooperate to maintain T-cell numbers in the mouse. Eur J Immunol 2013; 44:561-72. [PMID: 24510501 DOI: 10.1002/eji.201343750] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/29/2013] [Accepted: 09/26/2013] [Indexed: 12/29/2022]
Abstract
Gimap3 (IAN4) and Gimap5 (IAN5) are highly homologous GTP-binding proteins of the Gimap family. Gimap3 and Gimap5, whose transcripts are abundant in mature lymphocytes, can associate with antiapoptotic Bcl-2 family proteins. While it is established that Gimap5 regulates T-cell survival, the in vivo role of Gimap3 is unclear. Here we report the preparation and characteristics of mouse strains lacking Gimap3 and/or Gimap5. We found that the number of T cells was markedly reduced in mice deficient in both Gimap3 and Gimap5. The defects in T-cell cellularity were more severe in mice lacking both Gimap3 and Gimap5 than in mice lacking only Gimap5. No defects in the cellularity of T cells were detected in mice lacking only Gimap3, whereas bone marrow cells from Gimap3-deficient mice showed reduced T-cell production in a competitive hematopoietic environment. Moreover, retroviral overexpression and short hairpin RNAs-mediated silencing of Gimap3 in bone marrow cells elevated and reduced, respectively, the number of T cells produced in irradiated mice. These results suggest that Gimap3 is a regulator of T-cell numbers in the mouse and that multiple Gimap family proteins cooperate to maintain T-cell survival.
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Affiliation(s)
- Kouta Yano
- Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima, Japan
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42
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Pascall JC, Rotondo S, Mukadam AS, Oxley D, Webster J, Walker SA, Piron J, Carter C, Ktistakis NT, Butcher GW. The immune system GTPase GIMAP6 interacts with the Atg8 homologue GABARAPL2 and is recruited to autophagosomes. PLoS One 2013; 8:e77782. [PMID: 24204963 PMCID: PMC3804274 DOI: 10.1371/journal.pone.0077782] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 09/12/2013] [Indexed: 12/22/2022] Open
Abstract
The GIMAPs (GTPases of the immunity-associated proteins) are a family of small GTPases expressed prominently in the immune systems of mammals and other vertebrates. In mammals, studies of mutant or genetically-modified rodents have indicated important roles for the GIMAP GTPases in the development and survival of lymphocytes. No clear picture has yet emerged, however, of the molecular mechanisms by which they perform their function(s). Using biotin tag-affinity purification we identified a major, and highly specific, interaction between the human cytosolic family member GIMAP6 and GABARAPL2, one of the mammalian homologues of the yeast autophagy protein Atg8. Chemical cross-linking studies performed on Jurkat T cells, which express both GIMAP6 and GABARAPL2 endogenously, indicated that the two proteins in these cells readily associate with one another in the cytosol under normal conditions. The GIMAP6-GABARAPL2 interaction was disrupted by deletion of the last 10 amino acids of GIMAP6. The N-terminal region of GIMAP6, however, which includes a putative Atg8-family interacting motif, was not required. Over-expression of GIMAP6 resulted in increased levels of endogenous GABARAPL2 in cells. After culture of cells in starvation medium, GIMAP6 was found to localise in punctate structures with both GABARAPL2 and the autophagosomal marker MAP1LC3B, indicating that GIMAP6 re-locates to autophagosomes on starvation. Consistent with this finding, we have demonstrated that starvation of Jurkat T cells results in the degradation of GIMAP6. Whilst these findings raise the possibility that the GIMAPs play roles in the regulation of autophagy, we have been unable to demonstrate an effect of GIMAP6 over-expression on autophagic flux.
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Affiliation(s)
- John C. Pascall
- The Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Sergio Rotondo
- The Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Aamir S. Mukadam
- The Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - David Oxley
- Laboratory of Lymphocyte Signalling and Development, the Mass Spectrometry Facility, the Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Judith Webster
- Laboratory of Lymphocyte Signalling and Development, the Mass Spectrometry Facility, the Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Simon A. Walker
- The Imaging Facility, the Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Jerry Piron
- The Monoclonal Antibody Unit, the Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Christine Carter
- The Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Nicholas T. Ktistakis
- The Inositide Laboratory, the Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
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43
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Affiliation(s)
- Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, New York
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44
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Lombès A, Auré K, Bellanné-Chantelot C, Gilleron M, Jardel C. Unsolved issues related to human mitochondrial diseases. Biochimie 2013; 100:171-6. [PMID: 23973280 DOI: 10.1016/j.biochi.2013.08.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 08/10/2013] [Indexed: 12/21/2022]
Abstract
Human mitochondrial diseases, defined as the diseases due to a mitochondrial oxidative phosphorylation defect, represent a large group of very diverse diseases with respect to phenotype and genetic causes. They present with many unsolved issues, the comprehensive analysis of which is beyond the scope of this review. We here essentially focus on the mechanisms underlying the diversity of targeted tissues, which is an important component of the large panel of these diseases phenotypic expression. The reproducibility of genotype/phenotype expression, the presence of modifying factors, and the potential causes for the restricted pattern of tissular expression are reviewed. Special emphasis is made on heteroplasmy, a specific feature of mitochondrial diseases, defined as the coexistence within the cell of mutant and wild type mitochondrial DNA molecules. Its existence permits unequal segregation during mitoses of the mitochondrial DNA populations and consequently heterogeneous tissue distribution of the mutation load. The observed tissue distributions of recurrent human mitochondrial DNA deleterious mutations are diverse but reproducible for a given mutation demonstrating that the segregation is not a random process. Its extent and mechanisms remain essentially unknown despite recent advances obtained in animal models.
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Affiliation(s)
- Anne Lombès
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; Université Paris-Descartes-Paris5, Paris F-75014, France; AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
| | - Karine Auré
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; AP-HP, Hôpital Ambroise Paré, Service d'explorations fonctionnelles, Boulogne-Billancourt F-92100, France; Université Versailles-Saint-Quentin en Yvelines, Faculté de Médecine, F-78180, France.
| | - Christine Bellanné-Chantelot
- AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
| | - Mylène Gilleron
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
| | - Claude Jardel
- Inserm Institut Cochin U1016, CNRS UMR 8104, 24 rue du Fb St Jacques, Paris F-75014, France; AP-HP, Service de Biochimie Métabolique et Centre de Génétique moléculaire et chromosomique, GHU Pitié-Salpêtrière, Paris F-75651, France.
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45
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Abstract
Mitochondrial DNA (mtDNA) is essential for aerobic energy production in eukaryotic cells, and mutations in this genome can lead to mitochondrial dysfunction. Human mtDNA mutations are typically heteroplasmic, a mix of mutant and wild-type genomes, which can present as a heterogeneous group of disorders ranging in severity from mild to fatal, and commonly affecting highly aerobic tissues such as heart, skeletal muscle, and neurons. During the 1990s, many research groups started to notice that mtDNA mutations could segregate depending upon the mutation and tissue. This segregation pattern can have a direct effect on the onset and severity of these mutations. However, these segregation patterns could not be easily explained by respiratory chain function, implying that there is regulation of mtDNA independent of its bioenergetic role. A lot of research on this topic has been largely descriptive, but over the last several years advances in mitochondrial biology have provided some mechanistic insight into the regulation of the organelle and its genome. This review addresses these advances with respect to somatic segregation of mtDNA in mammals.
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Affiliation(s)
- Riikka Jokinen
- Research Programs Unit-Molecular Neurology, and Institute of Biomedicine, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
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46
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Sharpley MS, Marciniak C, Eckel-Mahan K, McManus M, Crimi M, Waymire K, Lin CS, Masubuchi S, Friend N, Koike M, Chalkia D, MacGregor G, Sassone-Corsi P, Wallace DC. Heteroplasmy of mouse mtDNA is genetically unstable and results in altered behavior and cognition. Cell 2012; 151:333-343. [PMID: 23063123 DOI: 10.1016/j.cell.2012.09.004] [Citation(s) in RCA: 256] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2012] [Revised: 06/08/2012] [Accepted: 08/20/2012] [Indexed: 12/24/2022]
Abstract
Maternal inheritance of mtDNA is the rule in most animals, but the reasons for this pattern remain unclear. To investigate the consequence of overriding uniparental inheritance, we generated mice containing an admixture (heteroplasmy) of NZB and 129S6 mtDNAs in the presence of a congenic C57BL/6J nuclear background. Analysis of the segregation of the two mtDNAs across subsequent maternal generations revealed that proportion of NZB mtDNA was preferentially reduced. Ultimately, this segregation process produced NZB-129 heteroplasmic mice and their NZB or 129 mtDNA homoplasmic counterparts. Phenotypic comparison of these three mtDNA lines demonstrated that the NZB-129 heteroplasmic mice, but neither homoplasmic counterpart, had reduced activity, food intake, respiratory exchange ratio; accentuated stress response; and cognitive impairment. Therefore, admixture of two normal but different mouse mtDNAs can be genetically unstable and can produce adverse physiological effects, factors that may explain the advantage of uniparental inheritance of mtDNA.
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Affiliation(s)
- Mark S Sharpley
- Center for Mitochondrial and Epigenomic Medicine, the Children's Hospital of Philadelphia and the Department of Pathology and Laboratory Medicine, University of Pennsylvania, Colket Translational Research Building, Philadelphia, PA 19104-4302, USA.,Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Christine Marciniak
- Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Kristin Eckel-Mahan
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA.,Center for Epigenetics and Metabolism, University of California, Irvine, Irvine, CA 92697, USA
| | - Meagan McManus
- Center for Mitochondrial and Epigenomic Medicine, the Children's Hospital of Philadelphia and the Department of Pathology and Laboratory Medicine, University of Pennsylvania, Colket Translational Research Building, Philadelphia, PA 19104-4302, USA
| | - Marco Crimi
- Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Katrina Waymire
- Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA.,Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Chun Shi Lin
- Center for Mitochondrial and Epigenomic Medicine, the Children's Hospital of Philadelphia and the Department of Pathology and Laboratory Medicine, University of Pennsylvania, Colket Translational Research Building, Philadelphia, PA 19104-4302, USA.,Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Satoru Masubuchi
- Center for Epigenetics and Metabolism, University of California, Irvine, Irvine, CA 92697, USA
| | - Nicole Friend
- Center for Mitochondrial and Epigenomic Medicine, the Children's Hospital of Philadelphia and the Department of Pathology and Laboratory Medicine, University of Pennsylvania, Colket Translational Research Building, Philadelphia, PA 19104-4302, USA.,Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Maya Koike
- Center for Mitochondrial and Epigenomic Medicine, the Children's Hospital of Philadelphia and the Department of Pathology and Laboratory Medicine, University of Pennsylvania, Colket Translational Research Building, Philadelphia, PA 19104-4302, USA
| | - Dimitra Chalkia
- Center for Mitochondrial and Epigenomic Medicine, the Children's Hospital of Philadelphia and the Department of Pathology and Laboratory Medicine, University of Pennsylvania, Colket Translational Research Building, Philadelphia, PA 19104-4302, USA.,Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
| | - Grant MacGregor
- Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Paolo Sassone-Corsi
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA.,Center for Epigenetics and Metabolism, University of California, Irvine, Irvine, CA 92697, USA
| | - Douglas C Wallace
- Center for Mitochondrial and Epigenomic Medicine, the Children's Hospital of Philadelphia and the Department of Pathology and Laboratory Medicine, University of Pennsylvania, Colket Translational Research Building, Philadelphia, PA 19104-4302, USA.,Center for Molecular and Mitochondrial Medicine and Genetics, University of California, Irvine, Irvine, CA 92697, USA.,Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
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47
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Maintenance of mitochondrial genome distribution by mitochondrial AAA+ protein ClpX. Exp Cell Res 2012; 318:2335-43. [PMID: 22841477 DOI: 10.1016/j.yexcr.2012.07.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 06/22/2012] [Accepted: 07/10/2012] [Indexed: 11/20/2022]
Abstract
The segregation of mitochondrial DNA (mtDNA) is important for the maintenance and transmission of the genome between generations. Recently, we clarified that human mitochondrial transcription factor A (TFAM) is required for equal distribution and symmetric segregation of mtDNA in cultured cells; however, the molecular mechanism involved is largely unknown. ClpX is an ATPase associated with various cellular activities (AAA+) proteins that localize to the mitochondrial matrix and is suggested to associate with mtDNA. In this study, we found that RNAi-mediated knockdown of ClpX in HeLa cells resulted in enlarged mtDNA nucleoids, which is very similar to that observed in TFAM-knockdown cells in several properties. The expression of TFAM protein was not significantly reduced in ClpX-knockdown cells. However, the enlarged mtDNA nucleoids caused by ClpX-knockdown were suppressed by overexpression of recombinant TFAM and the phenotype was not observed in knockdown with ClpP, a protease subunit of ClpXP. Endogenous ClpX and TFAM exist in close vicinity, and ClpX enhanced DNA-binding activity of TFAM in vitro. These results suggest that human ClpX, a novel mtDNA regulator, maintains mtDNA nucleoid distribution through TFAM function as a chaperone rather than as a protease and its involvement in mtDNA segregation.
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48
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Shutt TE, McBride HM. Staying cool in difficult times: mitochondrial dynamics, quality control and the stress response. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:417-24. [PMID: 22683990 DOI: 10.1016/j.bbamcr.2012.05.024] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 05/21/2012] [Accepted: 05/22/2012] [Indexed: 12/30/2022]
Abstract
One of the critical problems with the combustion of sugar and fat is the generation of cellular oxidation. The ongoing consumption of oxygen results in damage to lipids, protein and mtDNA, which must be repaired through essential pathways in mitochondrial quality control. It has long been established that intrinsic protease pathways within the matrix and intermembrane space actively degrade unfolded and oxidized mitochondrial proteins. However, more recent work into the field of quality control has established distinct roles for both mitochondrial fragmentation and hyperfusion in different aspects of quality control and survival. In addition, mitochondrial derived vesicles have recently been shown to carry cargo directly to the lysosome, adding further insight into the integration of mitochondrial dynamics in cellular homeostasis. This review will focus on the mechanisms and emerging questions concerning the links between mitochondrial dynamics and quality control. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Affiliation(s)
- Timothy E Shutt
- University of Ottawa Heart Institute, 40 Ruskin St., Ottawa, ON, Canada K1Y 4W7
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49
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Abstract
Mitochondria perform diverse yet interconnected functions, producing ATP and many biosynthetic intermediates while also contributing to cellular stress responses such as autophagy and apoptosis. Mitochondria form a dynamic, interconnected network that is intimately integrated with other cellular compartments. In addition, mitochondrial functions extend beyond the boundaries of the cell and influence an organism's physiology by regulating communication between cells and tissues. It is therefore not surprising that mitochondrial dysfunction has emerged as a key factor in a myriad of diseases, including neurodegenerative and metabolic disorders. We provide a current view of how mitochondrial functions impinge on health and disease.
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Affiliation(s)
- Jodi Nunnari
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
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50
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Abstract
Mutations that arise in mitochondrial DNA (mtDNA) may be sporadic, maternally inherited, or Mendelian in character and include mtDNA rearrangements such as deletions, inversions or duplications, point mutations, or copy number depletion. Primary mtDNA mutations occur sporadically or exhibit maternal inheritance and arise due in large part to the high mutation rate of mtDNA. mtDNA mutations may also occur because of defects in the biogenesis or maintenance of mtDNA, reflecting the contribution of nuclear-encoded genes to these processes, and in this case exhibit Mendelian inheritance. Whether maternally inherited, sporadic, or Mendelian, mtDNA mutations can exhibit a complex and broad spectrum of disease manifestations due to the central role mitochondria play in a variety of cellular functions. In addition, because there exist hundreds to thousands of copies of mtDNA in each cell, the proportion of mutant mtDNA molecules can have a profound effect on the cellular and clinical phenotype. This chapter reviews the classification of mtDNA mutations and the clinical features that determine the diagnosis of a primary mtDNA disorder.
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Affiliation(s)
- William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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