1
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Tomar A, Gomez-Velazquez M, Gerlini R, Comas-Armangué G, Makharadze L, Kolbe T, Boersma A, Dahlhoff M, Burgstaller JP, Lassi M, Darr J, Toppari J, Virtanen H, Kühnapfel A, Scholz M, Landgraf K, Kiess W, Vogel M, Gailus-Durner V, Fuchs H, Marschall S, Hrabě de Angelis M, Kotaja N, Körner A, Teperino R. Epigenetic inheritance of diet-induced and sperm-borne mitochondrial RNAs. Nature 2024; 630:720-727. [PMID: 38839949 PMCID: PMC11186758 DOI: 10.1038/s41586-024-07472-3] [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: 06/30/2023] [Accepted: 04/26/2024] [Indexed: 06/07/2024]
Abstract
Spermatozoa harbour a complex and environment-sensitive pool of small non-coding RNAs (sncRNAs)1, which influences offspring development and adult phenotypes1-7. Whether spermatozoa in the epididymis are directly susceptible to environmental cues is not fully understood8. Here we used two distinct paradigms of preconception acute high-fat diet to dissect epididymal versus testicular contributions to the sperm sncRNA pool and offspring health. We show that epididymal spermatozoa, but not developing germ cells, are sensitive to the environment and identify mitochondrial tRNAs (mt-tRNAs) and their fragments (mt-tsRNAs) as sperm-borne factors. In humans, mt-tsRNAs in spermatozoa correlate with body mass index, and paternal overweight at conception doubles offspring obesity risk and compromises metabolic health. Sperm sncRNA sequencing of mice mutant for genes involved in mitochondrial function, and metabolic phenotyping of their wild-type offspring, suggest that the upregulation of mt-tsRNAs is downstream of mitochondrial dysfunction. Single-embryo transcriptomics of genetically hybrid two-cell embryos demonstrated sperm-to-oocyte transfer of mt-tRNAs at fertilization and suggested their involvement in the control of early-embryo transcription. Our study supports the importance of paternal health at conception for offspring metabolism, shows that mt-tRNAs are diet-induced and sperm-borne and demonstrates, in a physiological setting, father-to-offspring transfer of sperm mitochondrial RNAs at fertilization.
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MESH Headings
- Animals
- Female
- Humans
- Male
- Mice
- Body Mass Index
- Diet, High-Fat/adverse effects
- Embryo, Mammalian/cytology
- Embryo, Mammalian/embryology
- Embryo, Mammalian/metabolism
- Epididymis/cytology
- Epigenesis, Genetic/genetics
- Fertilization/genetics
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Mice, Inbred C57BL
- Mitochondria/genetics
- Mitochondria/metabolism
- Mitochondria/pathology
- Obesity/genetics
- Obesity/metabolism
- Obesity/etiology
- Oocytes/metabolism
- Overweight/genetics
- Overweight/metabolism
- Paternal Inheritance/genetics
- RNA, Mitochondrial/genetics
- RNA, Mitochondrial/metabolism
- RNA, Small Untranslated/genetics
- RNA, Small Untranslated/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- Spermatozoa/metabolism
- Testis/cytology
- Transcription, Genetic
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Affiliation(s)
- A Tomar
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - M Gomez-Velazquez
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - R Gerlini
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - G Comas-Armangué
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - L Makharadze
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - T Kolbe
- Unit of in vivo and in vitro Models, Center for Biological Sciences, Department of Biological Sciences and Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
- IFA-Tulln, University of Natural Resources and Life Sciences, Vienna, Austria
| | - A Boersma
- Unit of in vivo and in vitro Models, Center for Biological Sciences, Department of Biological Sciences and Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - M Dahlhoff
- Unit of in vivo and in vitro Models, Center for Biological Sciences, Department of Biological Sciences and Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - J P Burgstaller
- Institute of Animal Breeding and Genetics, Department of Biological Sciences and Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria
- Group Molecular Reproduction, IFA-Tulln, Tulln, Austria
| | - M Lassi
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - J Darr
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - J Toppari
- Institute of Biomedicine, Integrative Physiology and Pharmacology Unit, University of Turku, Turku, Finland
- Center for Population Health Research, University of Turku and Turku University Hospital, Turku, Finland
| | - H Virtanen
- Institute of Biomedicine, Integrative Physiology and Pharmacology Unit, University of Turku, Turku, Finland
- Center for Population Health Research, University of Turku and Turku University Hospital, Turku, Finland
| | - A Kühnapfel
- University of Leipzig, Medical Faculty, Institute for Medical Informatics, Statistics and Epidemiology, Leipzig, Germany
| | - M Scholz
- University of Leipzig, Medical Faculty, Institute for Medical Informatics, Statistics and Epidemiology, Leipzig, Germany
| | - K Landgraf
- Center for Pediatric Research Leipzig (CPL), Hospital for Children & Adolescents, University of Leipzig, Leipzig, Germany
| | - W Kiess
- Center for Pediatric Research Leipzig (CPL), Hospital for Children & Adolescents, University of Leipzig, Leipzig, Germany
- LIFE Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - M Vogel
- Center for Pediatric Research Leipzig (CPL), Hospital for Children & Adolescents, University of Leipzig, Leipzig, Germany
- LIFE Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
| | - V Gailus-Durner
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - H Fuchs
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - S Marschall
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - M Hrabě de Angelis
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- German Center for Diabetes Research (DZD), Neuherberg, Germany
- German Mouse Clinic, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany
- Chair of Experimental Genetics, TUM School of Life Sciences, Technische Universität München, Freising, Germany
| | - N Kotaja
- Institute of Biomedicine, Integrative Physiology and Pharmacology Unit, University of Turku, Turku, Finland
| | - A Körner
- Center for Pediatric Research Leipzig (CPL), Hospital for Children & Adolescents, University of Leipzig, Leipzig, Germany
- LIFE Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany
- Helmholtz Institute for Metabolic Obesity and Vascular Research (HI-MAG), Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany
| | - R Teperino
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Neuherberg, Germany.
- German Center for Diabetes Research (DZD), Neuherberg, Germany.
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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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Broz AK, Sloan DB, Johnston IG. Stochastic organelle genome segregation through Arabidopsis development and reproduction. THE NEW PHYTOLOGIST 2024; 241:896-910. [PMID: 37925790 PMCID: PMC10841260 DOI: 10.1111/nph.19288] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 09/07/2023] [Indexed: 11/07/2023]
Abstract
Organelle DNA (oDNA) in mitochondria and plastids is vital for plant (and eukaryotic) life. Selection against damaged oDNA is mediated in part by segregation - sorting different oDNA types into different cells in the germline. Plants segregate oDNA very rapidly, with oDNA recombination protein MSH1 a key driver of this segregation, but we have limited knowledge of the dynamics of this segregation within plants and between generations. Here, we reveal how oDNA evolves through Arabidopsis thaliana development and reproduction. We combine stochastic modelling, Bayesian inference, and model selection with new and existing tissue-specific oDNA measurements from heteroplasmic Arabidopsis plant lines through development and between generations. Segregation proceeds gradually but continually during plant development, with a more rapid increase between inflorescence formation and the next generation. When MSH1 is compromised, the majority of observed segregation can be achieved through partitioning at cell divisions. When MSH1 is functional, mtDNA segregation is far more rapid; we show that increased oDNA gene conversion is a plausible mechanism quantitatively explaining this acceleration. These findings reveal the quantitative, time-dependent details of oDNA segregation in Arabidopsis. We also discuss the support for different models of the plant germline provided by these observations.
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Affiliation(s)
- Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Iain G Johnston
- Department of Mathematics, University of Bergen, Bergen, 5007, Norway
- Computational Biology Unit, University of Bergen, Bergen, 5007, Norway
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4
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Giannakis K, Broz AK, Sloan DB, Johnston IG. Avoiding misleading estimates using mtDNA heteroplasmy statistics to study bottleneck size and selection. G3 (BETHESDA, MD.) 2023; 13:jkad068. [PMID: 36951404 PMCID: PMC10234379 DOI: 10.1093/g3journal/jkad068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 10/18/2022] [Accepted: 03/10/2023] [Indexed: 03/24/2023]
Abstract
Mitochondrial DNA heteroplasmy samples can shed light on vital developmental and genetic processes shaping mitochondrial DNA populations. The sample means and sample variance of a set of heteroplasmy observations are typically used both to estimate bottleneck sizes and to perform fits to the theoretical "Kimura" distribution in seeking evidence for mitochondrial DNA selection. However, each of these applications raises problems. Sample statistics do not generally provide optimal fits to the Kimura distribution and so can give misleading results in hypothesis testing, including false positive signals of selection. Using sample variance can give misleading results for bottleneck size estimates, particularly for small samples. These issues can and do lead to false positive results for mitochondrial DNA mechanisms-all published experimental datasets we re-analyzed, reported as displaying departures from the Kimura model, do not in fact give evidence for such departures. Here we outline a maximum likelihood approach that is simple to implement computationally and addresses all of these issues. We advocate the use of maximum likelihood fits and explicit hypothesis tests, not fits and Kolmogorov-Smirnov tests via summary statistics, for ongoing work with mitochondrial DNA heteroplasmy.
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Affiliation(s)
| | - Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Iain G Johnston
- Department of Mathematics, University of Bergen, 5007 Bergen, Norway
- Computational Biology Unit, University of Bergen, 5008 Bergen, Norway
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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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Glastad RC, Johnston IG. Mitochondrial network structure controls cell-to-cell mtDNA variability generated by cell divisions. PLoS Comput Biol 2023; 19:e1010953. [PMID: 36952562 PMCID: PMC10072490 DOI: 10.1371/journal.pcbi.1010953] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 04/04/2023] [Accepted: 02/15/2023] [Indexed: 03/25/2023] Open
Abstract
Mitochondria are highly dynamic organelles, containing vital populations of mitochondrial DNA (mtDNA) distributed throughout the cell. Mitochondria form diverse physical structures in different cells, from cell-wide reticulated networks to fragmented individual organelles. These physical structures are known to influence the genetic makeup of mtDNA populations between cell divisions, but their influence on the inheritance of mtDNA at divisions remains less understood. Here, we use statistical and computational models of mtDNA content inside and outside the reticulated network to quantify how mitochondrial network structure can control the variances of inherited mtDNA copy number and mutant load. We assess the use of moment-based approximations to describe heteroplasmy variance and identify several cases where such an approach has shortcomings. We show that biased inclusion of one mtDNA type in the network can substantially increase heteroplasmy variance (acting as a genetic bottleneck), and controlled distribution of network mass and mtDNA through the cell can conversely reduce heteroplasmy variance below a binomial inheritance picture. Network structure also allows the generation of heteroplasmy variance while controlling copy number inheritance to sub-binomial levels, reconciling several observations from the experimental literature. Overall, different network structures and mtDNA arrangements within them can control the variances of key variables to suit a palette of different inheritance priorities.
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Affiliation(s)
| | - Iain G. Johnston
- Department of Mathematics, University of Bergen, Bergen, Norway
- Computational Biology Unit, University of Bergen, Bergen, Norway
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7
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Dong LF, Rohlena J, Zobalova R, Nahacka Z, Rodriguez AM, Berridge MV, Neuzil J. Mitochondria on the move: Horizontal mitochondrial transfer in disease and health. J Cell Biol 2023; 222:213873. [PMID: 36795453 PMCID: PMC9960264 DOI: 10.1083/jcb.202211044] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 01/12/2023] [Accepted: 02/01/2023] [Indexed: 02/17/2023] Open
Abstract
Mammalian genes were long thought to be constrained within somatic cells in most cell types. This concept was challenged recently when cellular organelles including mitochondria were shown to move between mammalian cells in culture via cytoplasmic bridges. Recent research in animals indicates transfer of mitochondria in cancer and during lung injury in vivo, with considerable functional consequences. Since these pioneering discoveries, many studies have confirmed horizontal mitochondrial transfer (HMT) in vivo, and its functional characteristics and consequences have been described. Additional support for this phenomenon has come from phylogenetic studies. Apparently, mitochondrial trafficking between cells occurs more frequently than previously thought and contributes to diverse processes including bioenergetic crosstalk and homeostasis, disease treatment and recovery, and development of resistance to cancer therapy. Here we highlight current knowledge of HMT between cells, focusing primarily on in vivo systems, and contend that this process is not only (patho)physiologically relevant, but also can be exploited for the design of novel therapeutic approaches.
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Affiliation(s)
- Lan-Feng Dong
- https://ror.org/02sc3r913School of Pharmacy and Medical Sciences, Griffith University, Southport, Australia,Lan-Feng Dong:
| | - Jakub Rohlena
- https://ror.org/00wzqmx94Institute of Biotechnology, Academy of Sciences of the Czech Republic, Prague-West, Czech Republic
| | - Renata Zobalova
- https://ror.org/00wzqmx94Institute of Biotechnology, Academy of Sciences of the Czech Republic, Prague-West, Czech Republic
| | - Zuzana Nahacka
- https://ror.org/00wzqmx94Institute of Biotechnology, Academy of Sciences of the Czech Republic, Prague-West, Czech Republic
| | | | | | - Jiri Neuzil
- https://ror.org/02sc3r913School of Pharmacy and Medical Sciences, Griffith University, Southport, Australia,https://ror.org/00wzqmx94Institute of Biotechnology, Academy of Sciences of the Czech Republic, Prague-West, Czech Republic,Faculty of Science, Charles University, Prague, Czech Republic,First Faculty of Medicine, Charles University, Prague, Czech Republic,Correspondence to Jiri Neuzil: ,
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8
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Burgstaller JP, Chiaratti MR. Mitochondrial Inheritance Following Nuclear Transfer: From Cloned Animals to Patients with Mitochondrial Disease. Methods Mol Biol 2023; 2647:83-104. [PMID: 37041330 DOI: 10.1007/978-1-0716-3064-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Mitochondria are indispensable power plants of eukaryotic cells that also act as a major biochemical hub. As such, mitochondrial dysfunction, which can originate from mutations in the mitochondrial genome (mtDNA), may impair organism fitness and lead to severe diseases in humans. MtDNA is a multi-copy, highly polymorphic genome that is uniparentally transmitted through the maternal line. Several mechanisms act in the germline to counteract heteroplasmy (i.e., coexistence of two or more mtDNA variants) and prevent expansion of mtDNA mutations. However, reproductive biotechnologies such as cloning by nuclear transfer can disrupt mtDNA inheritance, resulting in new genetic combinations that may be unstable and have physiological consequences. Here, we review the current understanding of mitochondrial inheritance, with emphasis on its pattern in animals and human embryos generated by nuclear transfer.
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Affiliation(s)
- Jörg P Burgstaller
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria
| | - Marcos R Chiaratti
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.
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9
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Kremer LS, Bozhilova LV, Rubalcava-Gracia D, Filograna R, Upadhyay M, Koolmeister C, Chinnery PF, Larsson NG. A role for BCL2L13 and autophagy in germline purifying selection of mtDNA. PLoS Genet 2023; 19:e1010573. [PMID: 36608143 PMCID: PMC9851501 DOI: 10.1371/journal.pgen.1010573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 01/19/2023] [Accepted: 12/14/2022] [Indexed: 01/09/2023] Open
Abstract
Mammalian mitochondrial DNA (mtDNA) is inherited uniparentally through the female germline without undergoing recombination. This poses a major problem as deleterious mtDNA mutations must be eliminated to avoid a mutational meltdown over generations. At least two mechanisms that can decrease the mutation load during maternal transmission are operational: a stochastic bottleneck for mtDNA transmission from mother to child, and a directed purifying selection against transmission of deleterious mtDNA mutations. However, the molecular mechanisms controlling these processes remain unknown. In this study, we systematically tested whether decreased autophagy contributes to purifying selection by crossing the C5024T mouse model harbouring a single pathogenic heteroplasmic mutation in the tRNAAla gene of the mtDNA with different autophagy-deficient mouse models, including knockouts of Parkin, Bcl2l13, Ulk1, and Ulk2. Our study reveals a statistically robust effect of knockout of Bcl2l13 on the selection process, and weaker evidence for the effect of Ulk1 and potentially Ulk2, while no statistically significant impact is seen for knockout of Parkin. This points at distinctive roles of these players in germline purifying selection. Overall, our approach provides a framework for investigating the roles of other important factors involved in the enigmatic process of purifying selection and guides further investigations for the role of BCL2L13 in the elimination of non-synonymous mutations in protein-coding genes.
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Affiliation(s)
- Laura S. Kremer
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Lyuba V. Bozhilova
- MRC Mitochondrial Biology Unit, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Diana Rubalcava-Gracia
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Roberta Filograna
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Mamta Upadhyay
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Camilla Koolmeister
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Patrick F. Chinnery
- MRC Mitochondrial Biology Unit, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- Department of Clinical Neuroscience, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (PFC); (N-GL)
| | - Nils-Göran Larsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
- * E-mail: (PFC); (N-GL)
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10
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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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11
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Tostes K, dos Santos AC, Alves LO, Bechara LRG, Marascalchi R, Macabelli CH, Grejo MP, Festuccia WT, Gottlieb RA, Ferreira JCB, Chiaratti MR. Autophagy deficiency abolishes liver mitochondrial DNA segregation. Autophagy 2022; 18:2397-2408. [PMID: 35220898 PMCID: PMC9542960 DOI: 10.1080/15548627.2022.2038501] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mutations in the mitochondrial genome (mtDNA) are ubiquitous in humans and can lead to a broad spectrum of disorders. However, due to the presence of multiple mtDNA molecules in the cell, co-existence of mutant and wild-type mtDNAs (termed heteroplasmy) can mask disease phenotype unless a threshold of mutant molecules is reached. Importantly, the mutant mtDNA level can change across lifespan as mtDNA segregates in an allele- and cell-specific fashion, potentially leading to disease. Segregation of mtDNA is mainly evident in hepatic cells, resulting in an age-dependent increase of mtDNA variants, including non-synonymous potentially deleterious mutations. Here we modeled mtDNA segregation using a well-established heteroplasmic mouse line with mtDNA of NZB/BINJ and C57BL/6N origin on a C57BL/6N nuclear background. This mouse line showed a pronounced age-dependent NZB mtDNA accumulation in the liver, thus leading to enhanced respiration capacity per mtDNA molecule. Remarkably, liver-specific atg7 (autophagy related 7) knockout abolished NZB mtDNA accumulat ion, resulting in close-to-neutral mtDNA segregation through development into adulthood. prkn (parkin RBR E3 ubiquitin protein ligase) knockout also partially prevented NZB mtDNA accumulation in the liver, but to a lesser extent. Hence, we propose that age-related liver mtDNA segregation is a consequence of macroautophagic clearance of the less-fit mtDNA. Considering that NZB/BINJ and C57BL/6N mtDNAs have a level of divergence comparable to that between human Eurasian and African mtDNAs, these findings have potential implications for humans, including the safe use of mitochondrial replacement therapy.Abbreviations: Apob: apolipoprotein B; Atg1: autophagy-related 1; Atg7: autophagy related 7; Atp5a1: ATP synthase, H+ transporting, mitochondrial F1 complex, alpha subunit 1; BL6: C57BL/6N mouse strain; BNIP3: BCL2/adenovirus E1B interacting protein 3; FCCP: carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; MAP1LC3A: microtubule-associated protein 1 light chain 3 alpha; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; mt-Atp8: mitochondrially encoded ATP synthase 8; MT-CO1: mitochondrially encoded cytochrome c oxidase I; MT-CO2: mitochondrially encoded cytochrome c oxidase II; mt-Co3: mitochondrially encoded cytochrome c oxidase III; mt-Cytb: mitochondrially encoded cytochrome b; mtDNA: mitochondrial DNA; MUL1: mitochondrial ubiquitin ligase activator of NFKB 1; nDNA: nuclear DNA; Ndufa9: NADH:ubiquinone oxireductase subunit A9; NDUFB8: NADH:ubiquinone oxireductase subunit B8; Nnt: nicotinamide nucleotide transhydrogenase; NZB: NZB/BINJ mouse strain; OXPHOS: oxidative phosphorylation; PINK1: PTEN induced putative kinase 1; Polg2: polymerase (DNA directed), gamma 2, accessory subunit; Ppara: peroxisome proliferator activated receptor alpha; Ppia: peptidylprolyl isomerase A; Prkn: parkin RBR E3 ubiquitin protein ligase; P10: post-natal day 10; P21: post-natal day 21; P100: post-natal day 100; qPCR: quantitative polymerase chain reaction; Rpl19: ribosomal protein L19; Rps18: ribosomal protein S18; SD: standard deviation; SEM: standard error of the mean; SDHB: succinate dehydrogenase complex, subunit B, iron sulfur (Ip); SQSTM1: sequestosome 1; Ssbp1: single-stranded DNA binding protein 1; TFAM: transcription factor A, mitochondrial; Tfb1m: transcription factor B1, mitochondrial; Tfb2m: transcription factor B2, mitochondrial; TOMM20: translocase of outer mitochondrial membrane 20; UQCRC2: ubiquinol cytochrome c reductase core protein 2; WT: wild-type.
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Affiliation(s)
- Katiane Tostes
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Angélica C. dos Santos
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Lindomar O. Alves
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Luiz R. G. Bechara
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Rachel Marascalchi
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Carolina H. Macabelli
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Mateus P. Grejo
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil
| | - William T. Festuccia
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Roberta A. Gottlieb
- Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Julio C. B. Ferreira
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil,Department of Chemical and Systems Biology, Stanford University School of Medicine, CA, USA
| | - Marcos R. Chiaratti
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil,CONTACT Marcos R. Chiaratti Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos13565-905, Brazil
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12
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Lechuga-Vieco AV, Latorre-Pellicer A, Calvo E, Torroja C, Pellico J, Acín-Pérez R, García-Gil ML, Santos A, Bagwan N, Bonzon-Kulichenko E, Magni R, Benito M, Justo-Méndez R, Simon AK, Sánchez-Cabo F, Vázquez J, Ruíz-Cabello J, Enríquez JA. Heteroplasmy of Wild Type Mitochondrial DNA Variants in Mice Causes Metabolic Heart Disease With Pulmonary Hypertension and Frailty. Circulation 2022; 145:1084-1101. [PMID: 35236094 PMCID: PMC8969846 DOI: 10.1161/circulationaha.121.056286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: In most eukaryotic cells, the mitochondrial DNA (mtDNA) is uniparentally transmitted and present in multiple copies derived from the clonal expansion of maternally inherited mtDNA. All copies are therefore near-identical, or homoplasmic. The presence of more than one mtDNA variant in the same cytoplasm can arise naturally or result from new medical technologies aimed at preventing mitochondrial genetic diseases and improving fertility. The latter is called divergent non-pathological mtDNAs heteroplasmy (DNPH). We hypothesized that DNPH is maladaptive and usually prevented by the cell. Methods: We engineered and characterized DNPH mice throughout their lifespan using transcriptomic, metabolomic, biochemical, physiological and phenotyping techniques. We focused on in vivo imaging techniques for non-invasive assessment of cardiac and pulmonary energy metabolism. Results: We show that DNPH impairs mitochondrial function, with profound consequences in critical tissues that cannot resolve heteroplasmy, particularly cardiac and skeletal muscle. Progressive metabolic stress in these tissues leads to severe pathology in adulthood, including pulmonary hypertension and heart failure, skeletal muscle wasting, frailty, and premature death. Symptom severity is strongly modulated by the nuclear context. Conclusions: Medical interventions that may generate DNPH should address potential incompatibilities between donor and recipient mtDNA.
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Affiliation(s)
- Ana Victoria Lechuga-Vieco
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain; The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom; Ciber de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Ana Latorre-Pellicer
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain; Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, ISS-Aragon, Zaragoza, Spain
| | - Enrique Calvo
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain
| | - Carlos Torroja
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain
| | - Juan Pellico
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain; Ciber de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Rebeca Acín-Pérez
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain
| | - María Luisa García-Gil
- Centro Nacional de Microscopia Electrónica (ICTS-CNME), Universidad Complutense de Madrid, Madrid, Spain
| | - Arnoldo Santos
- Ciber de Enfermedades Respiratorias (CIBERES), Madrid, Spain; ITC, Ingeniería y Técnicas Clínicas, Madrid, Spain
| | - Navratan Bagwan
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain
| | - Elena Bonzon-Kulichenko
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain; Ciber de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Ricardo Magni
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | | | - Raquel Justo-Méndez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Anna Katharina Simon
- The Kennedy Institute of Rheumatology, NDORMS, University of Oxford, Oxford, United Kingdom
| | | | - Jesús Vázquez
- Ciber de Fragilidad y Envejecimiento Saludable (CIBERFES) Madrid, Spain; Ciber de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain
| | - Jesús Ruíz-Cabello
- CIC biomaGUNE, 2014, Donostia-San Sebastián, Spain; IKERBASQUE, Basque Foundation for Science, Spain; Universidad Complutense de Madrid, Madrid, Spain
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13
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Meshnik L, Bar-Yaacov D, Kasztan D, Neiger T, Cohen T, Kishner M, Valenci I, Dadon S, Klein CJ, Vance JM, Nevo Y, Züchner S, Ovadia O, Mishmar D, Ben-Zvi A. Mutant C. elegans mitofusin leads to selective removal of mtDNA heteroplasmic deletions across generations to maintain fitness. BMC Biol 2022; 20:40. [PMID: 35139855 PMCID: PMC8829988 DOI: 10.1186/s12915-022-01241-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 01/28/2022] [Indexed: 11/20/2022] Open
Abstract
Background Mitochondrial DNA (mtDNA) is present at high copy numbers in animal cells, and though characterized by a single haplotype in each individual due to maternal germline inheritance, deleterious mutations and intact mtDNA molecules frequently co-exist (heteroplasmy). A number of factors, such as replicative segregation, mitochondrial bottlenecks, and selection, may modulate the exitance of heteroplasmic mutations. Since such mutations may have pathological consequences, they likely survive and are inherited due to functional complementation via the intracellular mitochondrial network. Here, we hypothesized that compromised mitochondrial fusion would hamper such complementation, thereby affecting heteroplasmy inheritance. Results We assessed heteroplasmy levels in three Caenorhabditis elegans strains carrying different heteroplasmic mtDNA deletions (ΔmtDNA) in the background of mutant mitofusin (fzo-1). Animals displayed severe embryonic lethality and developmental delay. Strikingly, observed phenotypes were relieved during subsequent generations in association with complete loss of ΔmtDNA molecules. Moreover, deletion loss rates were negatively correlated with the size of mtDNA deletions, suggesting that mitochondrial fusion is essential and sensitive to the nature of the heteroplasmic mtDNA mutations. Introducing the ΔmtDNA into a fzo-1;pdr-1;+/ΔmtDNA (PARKIN ortholog) double mutant resulted in a skewed Mendelian progeny distribution, in contrast to the normal distribution in the fzo-1;+/ΔmtDNA mutant, and severely reduced brood size. Notably, the ΔmtDNA was lost across generations in association with improved phenotypes. Conclusions Taken together, our findings show that when mitochondrial fusion is compromised, deleterious heteroplasmic mutations cannot evade natural selection while inherited through generations. Moreover, our findings underline the importance of cross-talk between mitochondrial fusion and mitophagy in modulating the inheritance of mtDNA heteroplasmy. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01241-2.
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Affiliation(s)
- Lana Meshnik
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dan Bar-Yaacov
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Department of Microbiology, Immunology and Genetics, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dana Kasztan
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Tali Neiger
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Tal Cohen
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Mor Kishner
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Itay Valenci
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Sara Dadon
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Christopher J Klein
- Department of Neurology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Jeffery M Vance
- Dr. John T. Macdonald Foundation Department of Human Genetics and Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Yoram Nevo
- Institute of Neurology, Schneider Children's Medical Center of Israel, Tel-Aviv University, Petach Tikva, Israel
| | - Stephan Züchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Ofer Ovadia
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dan Mishmar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Anat Ben-Zvi
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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14
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Emser SV, Schaschl H, Millesi E, Steinborn R. Extension of Mitogenome Enrichment Based on Single Long-Range PCR: mtDNAs and Putative Mitochondrial-Derived Peptides of Five Rodent Hibernators. Front Genet 2021; 12:685806. [PMID: 35027919 PMCID: PMC8749263 DOI: 10.3389/fgene.2021.685806] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 11/10/2021] [Indexed: 12/14/2022] Open
Abstract
Enriching mitochondrial DNA (mtDNA) for sequencing entire mitochondrial genomes (mitogenomes) can be achieved by single long-range PCR. This avoids interference from the omnipresent nuclear mtDNA sequences (NUMTs). The approach is currently restricted to the use of samples collected from humans and ray-finned fishes. Here, we extended the use of single long-range PCR by introducing back-to-back oligonucleotides that target a sequence of extraordinary homology across vertebrates. The assay was applied to five hibernating rodents, namely alpine marmot, Arctic and European ground squirrels, and common and garden dormice, four of which have not been fully sequenced before. Analysis of the novel mitogenomes focussed on the prediction of mitochondrial-derived peptides (MDPs) providing another level of information encoded by mtDNA. The comparison of MOTS-c, SHLP4 and SHLP6 sequences across vertebrate species identified segments of high homology that argue for future experimentation. In addition, we evaluated four candidate polymorphisms replacing an amino acid in mitochondrially encoded subunits of the oxidative phosphorylation (OXPHOS) system that were reported in relation to cold-adaptation. No obvious pattern was found for the diverse sets of mammalian species that either apply daily or multiday torpor or otherwise cope with cold. In summary, our single long-range PCR assay applying a pair of back-to-back primers that target a consensus sequence motif of Vertebrata has potential to amplify (intact) mitochondrial rings present in templates from a taxonomically diverse range of vertebrates. It could be promising for studying novel mitogenomes, mitotypes of a population and mitochondrial heteroplasmy in a sensitive, straightforward and flexible manner.
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Affiliation(s)
- Sarah V. Emser
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Helmut Schaschl
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
| | - Eva Millesi
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Ralf Steinborn
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
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15
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Zhang H, Esposito M, Pezet MG, Aryaman J, Wei W, Klimm F, Calabrese C, Burr SP, Macabelli CH, Viscomi C, Saitou M, Chiaratti MR, Stewart JB, Jones N, Chinnery PF. Mitochondrial DNA heteroplasmy is modulated during oocyte development propagating mutation transmission. SCIENCE ADVANCES 2021; 7:eabi5657. [PMID: 34878831 PMCID: PMC8654302 DOI: 10.1126/sciadv.abi5657] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 10/15/2021] [Indexed: 05/02/2023]
Abstract
Heteroplasmic mitochondrial DNA (mtDNA) mutations are a common cause of inherited disease, but a few recurrent mutations account for the vast majority of new families. The reasons for this are not known. We studied heteroplasmic mice transmitting m.5024C>T corresponding to a human pathogenic mutation. Analyzing 1167 mother-pup pairs, we show that m.5024C>T is preferentially transmitted from low to higher levels but does not reach homoplasmy. Single-cell analysis of the developing mouse oocytes showed the preferential increase in mutant over wild-type mtDNA in the absence of cell division. A similar inheritance pattern is seen in human pedigrees transmitting several pathogenic mtDNA mutations. In m.5024C>T mice, this can be explained by the preferential propagation of mtDNA during oocyte maturation, counterbalanced by purifying selection against high heteroplasmy levels. This could explain how a disadvantageous mutation in a carrier increases to levels that cause disease but fails to fixate, causing multigenerational heteroplasmic mtDNA disorders.
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Affiliation(s)
- Haixin Zhang
- 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
| | - Marco Esposito
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
- Leverhulme Centre for Cellular Bionics, Imperial College, London, UK
| | - Mikael G. Pezet
- 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
| | - Juvid Aryaman
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
| | - Wei Wei
- 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
| | - Florian Klimm
- 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
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
| | - Claudia Calabrese
- 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
| | - Stephen P. Burr
- 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
| | - Carolina H. Macabelli
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos 13565-905, Brazil
| | - Carlo Viscomi
- 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
| | - Mitinori Saitou
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
- JST, ERATO, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Marcos R. Chiaratti
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos 13565-905, Brazil
| | - James B. Stewart
- Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
- Biosciences Institute, Faculty of Medical Sciences, Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, UK
| | - Nick Jones
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College, London, UK
- Leverhulme Centre for Cellular Bionics, Imperial College, London, UK
| | - 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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16
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Lima A, Lubatti G, Burgstaller J, Hu D, Green AP, Di Gregorio A, Zawadzki T, Pernaute B, Mahammadov E, Perez-Montero S, Dore M, Sanchez JM, Bowling S, Sancho M, Kolbe T, Karimi MM, Carling D, Jones N, Srinivas S, Scialdone A, Rodriguez TA. Cell competition acts as a purifying selection to eliminate cells with mitochondrial defects during early mouse development. Nat Metab 2021; 3:1091-1108. [PMID: 34253906 PMCID: PMC7611553 DOI: 10.1038/s42255-021-00422-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 06/02/2021] [Indexed: 12/13/2022]
Abstract
Cell competition is emerging as a quality-control mechanism that eliminates unfit cells in a wide range of settings from development to the adult. However, the nature of the cells normally eliminated by cell competition and what triggers their elimination remains poorly understood. In mice, 35% of epiblast cells are eliminated before gastrulation. Here we show that cells with mitochondrial defects are eliminated by cell competition during early mouse development. Using single-cell transcriptional profiling of eliminated mouse epiblast cells, we identify hallmarks of cell competition and mitochondrial defects. We demonstrate that mitochondrial defects are common to a range of different loser cell types and that manipulating mitochondrial function triggers cell competition. Moreover, we show that in the mouse embryo, cell competition eliminates cells with sequence changes in mt-Rnr1 and mt-Rnr2, and that even non-pathological changes in mitochondrial DNA sequences can induce cell competition. Our results suggest that cell competition is a purifying selection that optimizes mitochondrial performance before gastrulation.
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Affiliation(s)
- Ana Lima
- National Heart and Lung Institute, Imperial College London, London, UK
- MRC London Institute of Medical Sciences (LMS), Institute of Clinical Sciences, Imperial College London, London, UK
| | - Gabriele Lubatti
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Jörg Burgstaller
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria
| | - Di Hu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Alistair P Green
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College London, London, UK
| | - Aida Di Gregorio
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Tamzin Zawadzki
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Barbara Pernaute
- National Heart and Lung Institute, Imperial College London, London, UK
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Elmir Mahammadov
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany
| | | | - Marian Dore
- MRC London Institute of Medical Sciences (LMS), Institute of Clinical Sciences, Imperial College London, London, UK
| | - Juan Miguel Sanchez
- National Heart and Lung Institute, Imperial College London, London, UK
- Orchard Therapeutics, London, UK
| | - Sarah Bowling
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Margarida Sancho
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Thomas Kolbe
- Biomodels Austria (Biat), University of Veterinary Medicine Vienna, Vienna, Austria
- Department IFA-Tulln, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Mohammad M Karimi
- MRC London Institute of Medical Sciences (LMS), Institute of Clinical Sciences, Imperial College London, London, UK
- Comprehensive Cancer Centre, School of Cancer & Pharmaceutical Sciences, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | - David Carling
- MRC London Institute of Medical Sciences (LMS), Institute of Clinical Sciences, Imperial College London, London, UK
| | - Nick Jones
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College London, London, UK
| | - Shankar Srinivas
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Antonio Scialdone
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany.
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany.
- Institute of Computational Biology, Helmholtz Zentrum München, Neuherberg, Germany.
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17
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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: 20] [Impact Index Per Article: 6.7] [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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18
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Ma H, Van Dyken C, Darby H, Mikhalchenko A, Marti-Gutierrez N, Koski A, Liang D, Li Y, Tippner-Hedges R, Kang E, Lee Y, Sidener H, Ramsey C, Hodge T, Amato P, Mitalipov S. Germline transmission of donor, maternal and paternal mtDNA in primates. Hum Reprod 2021; 36:493-505. [PMID: 33289786 DOI: 10.1093/humrep/deaa308] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/12/2020] [Indexed: 12/11/2022] Open
Abstract
STUDY QUESTION What are the long-term developmental, reproductive and genetic consequences of mitochondrial replacement therapy (MRT) in primates? SUMMARY ANSWER Longitudinal investigation of MRT rhesus macaques (Macaca mulatta) generated with donor mtDNA that is exceedingly distant from the original maternal counterpart suggest that their growth, general health and fertility is unremarkable and similar to controls. WHAT IS KNOWN ALREADY Mitochondrial gene mutations contribute to a diverse range of incurable human disorders. MRT via spindle transfer in oocytes was developed and proposed to prevent transmission of pathogenic mtDNA mutations from mothers to children. STUDY DESIGN, SIZE, DURATION The study provides longitudinal studies on general health, fertility as well as transmission and segregation of parental mtDNA haplotypes to various tissues and organs in five adult MRT rhesus macaques and their offspring. PARTICIPANTS/MATERIALS, SETTING, METHODS MRT was achieved by spindle transfer between metaphase II oocytes from genetically divergent rhesus macaque populations. After fertilization of oocytes with sperm, heteroplasmic zygotes contained an unequal mixture of three parental genomes, i.e. donor (≥97%), maternal (≤3%), and paternal (≤0.1%) mitochondrial (mt)DNA. MRT monkeys were grown to adulthood and their development and general health was regularly monitored. Reproductive fitness of male and female MRT macaques was evaluated by time-mated breeding and production of live offspring. The relative contribution of donor, maternal, and paternal mtDNA was measured by whole mitochondrial genome sequencing in all organs and tissues of MRT animals and their offspring. MAIN RESULTS AND THE ROLE OF CHANCE Both male and female MRT rhesus macaques containing unequal mixture of three parental genomes, i.e. donor (≥97%), maternal (≤3%), and paternal (≤0.1%) mtDNA reached healthy adulthood, were fertile and most animals stably maintained the initial ratio of parental mtDNA heteroplasmy and donor mtDNA was transmitted from females to offspring. However, in one monkey out of four analyzed, initially negligible maternal mtDNA heteroplasmy levels increased substantially up to 17% in selected internal tissues and organs. In addition, two monkeys showed paternal mtDNA contribution up to 33% in selected internal tissues and organs. LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION Conclusions in this study were made on a relatively low number of MRT monkeys, and on only one F1 (first generation) female. In addition, monkey MRT involved two wildtype mtDNA haplotypes, but not disease-relevant variants. Clinical trials on children born after MRT will be required to fully determine safety and efficacy of MRT for humans. WIDER IMPLICATIONS OF THE FINDINGS Our data show that MRT is compatible with normal postnatal development including overall health and reproductive fitness in nonhuman primates without any detected adverse effects. 'Mismatched' donor mtDNA in MRT animals even from the genetically distant mtDNA haplotypes did not cause secondary mitochondrial dysfunction. However, carry-over maternal or paternal mtDNA contributions increased substantially in selected internal tissues / organs of some MRT animals implying the possibility of mtDNA mutation recurrence. STUDY FUNDING/COMPETING INTEREST(S) This work has been funded by the grants from the Burroughs Wellcome Fund, the National Institutes of Health (RO1AG062459 and P51 OD011092), National Research Foundation of Korea (2018R1D1A1B07043216) and Oregon Health & Science University institutional funds. The authors declare no competing interests.
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Affiliation(s)
- Hong Ma
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA.,Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - Crystal Van Dyken
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA.,Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - Hayley Darby
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA.,Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - Aleksei Mikhalchenko
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Nuria Marti-Gutierrez
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Amy Koski
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Dan Liang
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Ying Li
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Rebecca Tippner-Hedges
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA
| | - Eunju Kang
- Stem Cell Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Yeonmi Lee
- Stem Cell Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Heather Sidener
- Division of Comparative Medicine, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - Cathy Ramsey
- Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - Travis Hodge
- Division of Comparative Medicine, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - Paula Amato
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA.,Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR, USA
| | - Shoukhrat Mitalipov
- Center for Embryonic Cell and Gene Therapy, Oregon Health & Science University, Portland, OR, USA.,Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
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19
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Meschaninova MI, Entelis NS, Chernolovskaya EL, Venyaminova AG. A Versatile Solid-Phase Approach to the Synthesis of Oligonucleotide Conjugates with Biodegradable Hydrazone Linker. Molecules 2021; 26:molecules26082119. [PMID: 33917095 PMCID: PMC8067880 DOI: 10.3390/molecules26082119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/03/2021] [Accepted: 04/04/2021] [Indexed: 12/02/2022] Open
Abstract
One of the ways to efficiently deliver various drugs, including therapeutic nucleic acids, into the cells is conjugating them with different transport ligands via labile or stable bonds. A convenient solid-phase approach for the synthesis of 5′-conjugates of oligonucleotides with biodegradable pH-sensitive hydrazone covalent bonds is proposed in this article. The approach relies on introducing a hydrazide of the ligand under aqueous/organic media to a fully protected support-bound oligonucleotide containing aldehyde function at the 5′-end. We demonstrated the proof-of-principle of this approach by synthesizing 5′-lipophilic (e.g., cholesterol and α-tocopherol) conjugates of modified siRNA and non-coding RNAs imported into mitochondria (antireplicative RNAs and guide RNAs for Mito-CRISPR/system). The developed method has the potential to be extended for the synthesis of pH-sensitive conjugates of oligonucleotides of different types (ribo-, deoxyribo-, 2′-O-methylribo-, and others) with ligands of different nature.
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Affiliation(s)
- Mariya I. Meschaninova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.L.C.); (A.G.V.)
- Correspondence: ; Tel.: +7-383-363-5129
| | - Nina S. Entelis
- UMR Genetique Moleculaire, Genomique, Microbiologie (GMGM), Strasbourg University—CNRS, 67084 Strasbourg, France;
| | - Elena L. Chernolovskaya
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.L.C.); (A.G.V.)
| | - Alya G. Venyaminova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk, Russia; (E.L.C.); (A.G.V.)
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20
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Sercel AJ, Carlson NM, Patananan AN, Teitell MA. Mitochondrial DNA Dynamics in Reprogramming to Pluripotency. Trends Cell Biol 2021; 31:311-323. [PMID: 33422359 PMCID: PMC7954944 DOI: 10.1016/j.tcb.2020.12.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 12/20/2022]
Abstract
Mammalian cells, with the exception of erythrocytes, harbor mitochondria, which are organelles that provide energy, intermediate metabolites, and additional activities to sustain cell viability, replication, and function. Mitochondria contain multiple copies of a circular genome called mitochondrial DNA (mtDNA), whose individual sequences are rarely identical (homoplasmy) because of inherited or sporadic mutations that result in multiple mtDNA genotypes (heteroplasmy). Here, we examine potential mechanisms for maintenance or shifts in heteroplasmy that occur in induced pluripotent stem cells (iPSCs) generated by cellular reprogramming, and further discuss manipulations that can alter heteroplasmy to impact stem and differentiated cell performance. This additional insight will assist in developing more robust iPSC-based models of disease and differentiated cell therapies.
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Affiliation(s)
- Alexander J Sercel
- Molecular Biology Interdepartmental Program, University of California, Los Angeles, Los Angeles, CA, USA 90095
| | - Natasha M Carlson
- Department of Biology, California State University Northridge, CA, USA 91330; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA 90095
| | - Alexander N Patananan
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA 90095
| | - Michael A Teitell
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA 90095; Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, USA 90095; California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, USA 90095; Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, USA 90095; Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research University of California, Los Angeles, Los Angeles, CA, USA 90095; Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA 90095; Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA 90095.
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21
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Iannello M, Bettinazzi S, Breton S, Ghiselli F, Milani L. A Naturally Heteroplasmic Clam Provides Clues about the Effects of Genetic Bottleneck on Paternal mtDNA. Genome Biol Evol 2021; 13:6130822. [PMID: 33555290 PMCID: PMC7936021 DOI: 10.1093/gbe/evab022] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2021] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial DNA (mtDNA) is present in multiple copies within an organism. Since these copies are not identical, a single individual carries a heterogeneous population of mtDNAs, a condition known as heteroplasmy. Several factors play a role in the dynamics of the within-organism mtDNA population: among them, genetic bottlenecks, selection, and strictly maternal inheritance are known to shape the levels of heteroplasmy across mtDNAs. In Metazoa, the only evolutionarily stable exception to the strictly maternal inheritance of mitochondria is the doubly uniparental inheritance (DUI), reported in 100+ bivalve species. In DUI species, there are two highly divergent mtDNA lineages, one inherited through oocyte mitochondria (F-type) and the other through sperm mitochondria (M-type). Having both parents contributing to the mtDNA pool of the progeny makes DUI a unique system to study the dynamics of mtDNA populations. Since, in bivalves, the spermatozoon has few mitochondria (4–5), M-type mtDNA faces a tight bottleneck during embryo segregation, one of the narrowest mitochondrial bottlenecks investigated so far. Here, we analyzed the F- and M-type mtDNA variability within individuals of the DUI species Ruditapes philippinarum and investigated for the first time the effects of such a narrow bottleneck affecting mtDNA populations. As a potential consequence of this narrow bottleneck, the M-type mtDNA shows a large variability in different tissues, a condition so pronounced that it leads to genotypes from different tissues of the same individual not to cluster together. We believe that such results may help understanding the effect of low population size on mtDNA bottleneck.
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Affiliation(s)
- Mariangela Iannello
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Italy
| | - Stefano Bettinazzi
- Department of Biological Sciences, University of Montreal, Quebec, Canada
| | - Sophie Breton
- Department of Biological Sciences, University of Montreal, Quebec, Canada
| | - Fabrizio Ghiselli
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Italy
| | - Liliana Milani
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Italy
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22
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Lechuga-Vieco AV, Justo-Méndez R, Enríquez JA. Not all mitochondrial DNAs are made equal and the nucleus knows it. IUBMB Life 2020; 73:511-529. [PMID: 33369015 PMCID: PMC7985871 DOI: 10.1002/iub.2434] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/06/2020] [Accepted: 12/09/2020] [Indexed: 12/13/2022]
Abstract
The oxidative phosphorylation (OXPHOS) system is the only structure in animal cells with components encoded by two genomes, maternally transmitted mitochondrial DNA (mtDNA), and biparentally transmitted nuclear DNA (nDNA). MtDNA‐encoded genes have to physically assemble with their counterparts encoded in the nucleus to build together the functional respiratory complexes. Therefore, structural and functional matching requirements between the protein subunits of these molecular complexes are rigorous. The crosstalk between nDNA and mtDNA needs to overcome some challenges, as the nuclear‐encoded factors have to be imported into the mitochondria in a correct quantity and match the high number of organelles and genomes per mitochondria that encode and synthesize their own components locally. The cell is able to sense the mito‐nuclear match through changes in the activity of the OXPHOS system, modulation of the mitochondrial biogenesis, or reactive oxygen species production. This implies that a complex signaling cascade should optimize OXPHOS performance to the cellular‐specific requirements, which will depend on cell type, environmental conditions, and life stage. Therefore, the mitochondria would function as a cellular metabolic information hub integrating critical information that would feedback the nucleus for it to respond accordingly. Here, we review the current understanding of the complex interaction between mtDNA and nDNA.
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Affiliation(s)
- Ana Victoria Lechuga-Vieco
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain.,MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Raquel Justo-Méndez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
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23
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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: 97] [Impact Index Per Article: 24.3] [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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24
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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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25
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Lechuga-Vieco AV, Latorre-Pellicer A, Johnston IG, Prota G, Gileadi U, Justo-Méndez R, Acín-Pérez R, Martínez-de-Mena R, Fernández-Toro JM, Jimenez-Blasco D, Mora A, Nicolás-Ávila JA, Santiago DJ, Priori SG, Bolaños JP, Sabio G, Criado LM, Ruíz-Cabello J, Cerundolo V, Jones NS, Enríquez JA. Cell identity and nucleo-mitochondrial genetic context modulate OXPHOS performance and determine somatic heteroplasmy dynamics. SCIENCE ADVANCES 2020; 6:eaba5345. [PMID: 32832682 PMCID: PMC7439646 DOI: 10.1126/sciadv.aba5345] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 06/17/2020] [Indexed: 05/02/2023]
Abstract
Heteroplasmy, multiple variants of mitochondrial DNA (mtDNA) in the same cytoplasm, may be naturally generated by mutations but is counteracted by a genetic mtDNA bottleneck during oocyte development. Engineered heteroplasmic mice with nonpathological mtDNA variants reveal a nonrandom tissue-specific mtDNA segregation pattern, with few tissues that do not show segregation. The driving force for this dynamic complex pattern has remained unexplained for decades, challenging our understanding of this fundamental biological problem and hindering clinical planning for inherited diseases. Here, we demonstrate that the nonrandom mtDNA segregation is an intracellular process based on organelle selection. This cell type-specific decision arises jointly from the impact of mtDNA haplotypes on the oxidative phosphorylation (OXPHOS) system and the cell metabolic requirements and is strongly sensitive to the nuclear context and to environmental cues.
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Affiliation(s)
- Ana Victoria Lechuga-Vieco
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- CIBERES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Ana Latorre-Pellicer
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, IIS Aragon, E-50009 Zaragoza, Spain
| | - Iain G. Johnston
- Department of Mathematics, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen, Norway
| | - Gennaro Prota
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Uzi Gileadi
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Raquel Justo-Méndez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Rebeca Acín-Pérez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | | | | | - Daniel Jimenez-Blasco
- IBFG, Universidad de Salamanca, Salamanca, Spain
- IBSAL, Hospital Universitario de Salamanca, Universidad de Salamanca, CSIC, Salamanca, Spain
- CIBERFES, C/Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Alfonso Mora
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | | | - Demetrio J. Santiago
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Molecular Cardiology, IRCCS ICS Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Silvia G. Priori
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- Molecular Cardiology, IRCCS ICS Maugeri, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Juan Pedro Bolaños
- IBFG, Universidad de Salamanca, Salamanca, Spain
- IBSAL, Hospital Universitario de Salamanca, Universidad de Salamanca, CSIC, Salamanca, Spain
- CIBERFES, C/Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Guadalupe Sabio
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Luis Miguel Criado
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Jesús Ruíz-Cabello
- CIBERES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain
- CIC biomaGUNE 20014 Donostia/San Sebastián, Gipuzkoa, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- Universidad Complutense Madrid, Madrid, Spain
| | - Vincenzo Cerundolo
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Nick S. Jones
- EPSRC Centre for the Mathematics of Precision Healthcare, Department of Mathematics, Imperial College London, London SW7 2BB, UK
| | - José Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- CIBERFES, C/Melchor Fernández-Almagro 3, 28029 Madrid, Spain
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26
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Vianello C, Cocetta V, Caicci F, Boldrin F, Montopoli M, Martinuzzi A, Carelli V, Giacomello M. Interaction Between Mitochondrial DNA Variants and Mitochondria/Endoplasmic Reticulum Contact Sites: A Perspective Review. DNA Cell Biol 2020; 39:1431-1443. [PMID: 32598172 DOI: 10.1089/dna.2020.5614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mitochondria contain their own genome, mitochondrial DNA (mtDNA), essential to support their fundamental intracellular role in ATP production and other key metabolic and homeostatic pathways. Mitochondria are highly dynamic organelles that communicate with all the other cellular compartments, through sites of high physical proximity. Among all, their crosstalk with the endoplasmic reticulum (ER) appears particularly important as its derangement is tightly implicated with several human disorders. Population-specific mtDNA variants clustered in defining the haplogroups have been shown to exacerbate or mitigate these pathological conditions. The exact mechanisms of the mtDNA background-modifying effect are not completely clear and a possible explanation is the outcome of mitochondrial efficiency on retrograde signaling to the nucleus. However, the possibility that different haplogroups shape the proximity and crosstalk between mitochondria and the ER has never been proposed neither investigated. In this study, we pose and discuss this question and provide preliminary data to answer it. Besides, we also address the possibility that single, disease-causing mtDNA point mutations may act also by reshaping organelle communication. Overall, this perspective review provides a theoretical platform for future studies on the interaction between mtDNA variants and organelle contact sites.
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Affiliation(s)
| | - Veronica Cocetta
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | | | | | - Monica Montopoli
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy.,VIMM-Veneto Institute of Molecular Medicine, Padova, Italy
| | - Andrea Martinuzzi
- Department of Neurorehabilitation, IRCCS "E. Medea" Scientific Institute, Conegliano Research Center, Treviso, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy.,IRCCS Istituto delle Scienze Neurologiche di Bologna, UOC Clinica Neurologica, Bologna, Italy
| | - Marta Giacomello
- Department of Biology, University of Padova, Padova, Italy.,Department of Biomedical Sciences, University of Padova, Padova, Italy
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27
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Klucnika A, Ma H. A battle for transmission: the cooperative and selfish animal mitochondrial genomes. Open Biol 2020; 9:180267. [PMID: 30890027 PMCID: PMC6451365 DOI: 10.1098/rsob.180267] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial genome is an evolutionarily persistent and cooperative component of metazoan cells that contributes to energy production and many other cellular processes. Despite sharing the same host as the nuclear genome, the multi-copy mitochondrial DNA (mtDNA) follows very different rules of replication and transmission, which translate into differences in the patterns of selection. On one hand, mtDNA is dependent on the host for its transmission, so selections would favour genomes that boost organismal fitness. On the other hand, genetic heterogeneity within an individual allows different mitochondrial genomes to compete for transmission. This intra-organismal competition could select for the best replicator, which does not necessarily give the fittest organisms, resulting in mito-nuclear conflict. In this review, we discuss the recent advances in our understanding of the mechanisms and opposing forces governing mtDNA transmission and selection in bilaterians, and what the implications of these are for mtDNA evolution and mitochondrial replacement therapy.
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Affiliation(s)
- Anna Klucnika
- 1 Wellcome Trust/Cancer Research UK Gurdon Institute , Tennis Court Road, Cambridge CB2 1QN , UK.,2 Department of Genetics, University of Cambridge , Downing Street, Cambridge CB2 3EH , UK
| | - Hansong Ma
- 1 Wellcome Trust/Cancer Research UK Gurdon Institute , Tennis Court Road, Cambridge CB2 1QN , UK.,2 Department of Genetics, University of Cambridge , Downing Street, Cambridge CB2 3EH , UK
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28
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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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Bettinazzi S, Rodríguez E, Milani L, Blier PU, Breton S. Metabolic remodelling associated with mtDNA: insights into the adaptive value of doubly uniparental inheritance of mitochondria. Proc Biol Sci 2020; 286:20182708. [PMID: 30963924 DOI: 10.1098/rspb.2018.2708] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mitochondria produce energy through oxidative phosphorylation (OXPHOS), which depends on the expression of both nuclear and mitochondrial DNA (mtDNA). In metazoans, a striking exception from strictly maternal inheritance of mitochondria is doubly uniparental inheritance (DUI). This unique system involves the maintenance of two highly divergent mtDNAs (F- and M-type, 8-40% of nucleotide divergence) associated with gametes, and occasionally coexisting in somatic tissues. To address whether metabolic differences underlie this condition, we characterized the OXPHOS activity of oocytes, spermatozoa, and gills of different species through respirometry. DUI species express different gender-linked mitochondrial phenotypes in gametes and partly in somatic tissues. The M-phenotype is specific to sperm and entails (i) low coupled/uncoupled respiration rates, (ii) a limitation by the phosphorylation system, and (iii) a null excess capacity of the final oxidases, supporting a strong control over the upstream complexes. To our knowledge, this is the first example of a phenotype resulting from direct selection on sperm mitochondria. This metabolic remodelling suggests an adaptive value of mtDNA variations and we propose that bearing sex-linked mitochondria could assure the energetic requirements of different gametes, potentially linking male-energetic adaptation, mitotype preservation and inheritance, as well as resistance to both heteroplasmy and ageing.
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Affiliation(s)
- Stefano Bettinazzi
- 1 Département de Sciences Biologiques, Université de Montréal , Montréal, QC, Canada H2V 2S9
| | - Enrique Rodríguez
- 2 Département de Biologie, Université du Québec , Rimouski, QC, Canada G5L 3A1
| | - Liliana Milani
- 3 Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna , Bologna 40126 , Italia
| | - Pierre U Blier
- 2 Département de Biologie, Université du Québec , Rimouski, QC, Canada G5L 3A1
| | - Sophie Breton
- 1 Département de Sciences Biologiques, Université de Montréal , Montréal, QC, Canada H2V 2S9
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van den Ameele J, Li AY, Ma H, Chinnery PF. Mitochondrial heteroplasmy beyond the oocyte bottleneck. Semin Cell Dev Biol 2020; 97:156-166. [DOI: 10.1016/j.semcdb.2019.10.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/17/2019] [Accepted: 10/01/2019] [Indexed: 12/31/2022]
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Latorre-Pellicer A, Lechuga-Vieco AV, Johnston IG, Hämäläinen RH, Pellico J, Justo-Méndez R, Fernández-Toro JM, Clavería C, Guaras A, Sierra R, Llop J, Torres M, Criado LM, Suomalainen A, Jones NS, Ruíz-Cabello J, Enríquez JA. Regulation of Mother-to-Offspring Transmission of mtDNA Heteroplasmy. Cell Metab 2019; 30:1120-1130.e5. [PMID: 31588014 PMCID: PMC6899444 DOI: 10.1016/j.cmet.2019.09.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 06/12/2019] [Accepted: 09/10/2019] [Indexed: 01/05/2023]
Abstract
mtDNA is present in multiple copies in each cell derived from the expansions of those in the oocyte. Heteroplasmy, more than one mtDNA variant, may be generated by mutagenesis, paternal mtDNA leakage, and novel medical technologies aiming to prevent inheritance of mtDNA-linked diseases. Heteroplasmy phenotypic impact remains poorly understood. Mouse studies led to contradictory models of random drift or haplotype selection for mother-to-offspring transmission of mtDNA heteroplasmy. Here, we show that mtDNA heteroplasmy affects embryo metabolism, cell fitness, and induced pluripotent stem cell (iPSC) generation. Thus, genetic and pharmacological interventions affecting oxidative phosphorylation (OXPHOS) modify competition among mtDNA haplotypes during oocyte development and/or at early embryonic stages. We show that heteroplasmy behavior can fall on a spectrum from random drift to strong selection, depending on mito-nuclear interactions and metabolic factors. Understanding heteroplasmy dynamics and its mechanisms provide novel knowledge of a fundamental biological process and enhance our ability to mitigate risks in clinical applications affecting mtDNA transmission.
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Affiliation(s)
- Ana Latorre-Pellicer
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain; Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, ISS-Aragon, 50009 Zaragoza, Spain
| | - Ana Victoria Lechuga-Vieco
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain; CIBERES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Iain G Johnston
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - Riikka H Hämäläinen
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; Research Program of Molecular Neurology, Biomedicum, University of Helsinki, Helsinki, Finland
| | - Juan Pellico
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain; CIBERES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain
| | - Raquel Justo-Méndez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | | | - Cristina Clavería
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Adela Guaras
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Rocío Sierra
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Jordi Llop
- CIC biomaGUNE, Paseo Miramón No 182, San Sebastián, 20014 Guipúzcoa, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Miguel Torres
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Luis Miguel Criado
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
| | - Anu Suomalainen
- Research Program of Molecular Neurology, Biomedicum, University of Helsinki, Helsinki, Finland
| | - Nick S Jones
- Department of Mathematics, Imperial College London, London SW7 2BB, UK
| | - Jesús Ruíz-Cabello
- CIBERES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain; CIC biomaGUNE, Paseo Miramón No 182, San Sebastián, 20014 Guipúzcoa, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain; Universidad Complutense de Madrid, Madrid 28606, Spain
| | - José Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain; CIBERFES: C/ Melchor Fernández-Almagro 3, 28029 Madrid, Spain.
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Poulton J, Steffann J, Burgstaller J, McFarland R. 243rd ENMC international workshop: Developing guidelines for management of reproductive options for families with maternally inherited mtDNA disease, Amsterdam, the Netherlands, 22–24 March 2019. Neuromuscul Disord 2019; 29:725-733. [DOI: 10.1016/j.nmd.2019.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/13/2019] [Indexed: 01/13/2023]
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Aryaman J, Bowles C, Jones NS, Johnston IG. Mitochondrial Network State Scales mtDNA Genetic Dynamics. Genetics 2019; 212:1429-1443. [PMID: 31253641 PMCID: PMC6707450 DOI: 10.1534/genetics.119.302423] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 06/28/2019] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial DNA (mtDNA) mutations cause severe congenital diseases but may also be associated with healthy aging. mtDNA is stochastically replicated and degraded, and exists within organelles which undergo dynamic fusion and fission. The role of the resulting mitochondrial networks in the time evolution of the cellular proportion of mutated mtDNA molecules (heteroplasmy), and cell-to-cell variability in heteroplasmy (heteroplasmy variance), remains incompletely understood. Heteroplasmy variance is particularly important since it modulates the number of pathological cells in a tissue. Here, we provide the first wide-reaching theoretical framework which bridges mitochondrial network and genetic states. We show that, under a range of conditions, the (genetic) rate of increase in heteroplasmy variance and de novo mutation are proportionally modulated by the (physical) fraction of unfused mitochondria, independently of the absolute fission-fusion rate. In the context of selective fusion, we show that intermediate fusion:fission ratios are optimal for the clearance of mtDNA mutants. Our findings imply that modulating network state, mitophagy rate, and copy number to slow down heteroplasmy dynamics when mean heteroplasmy is low could have therapeutic advantages for mitochondrial disease and healthy aging.
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Affiliation(s)
- Juvid Aryaman
- Department of Mathematics, Imperial College London, SW7 2AZ, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, CB2 0XY, United Kingdom
| | - Charlotte Bowles
- School of Biosciences, University of Birmingham, B15 2TT, United Kingdom
| | - Nick S Jones
- Department of Mathematics, Imperial College London, SW7 2AZ, United Kingdom
- Engineering and Physical Sciences Research Council Centre for the Mathematics of Precision Healthcare, Imperial College London, SW7 2AZ, United Kingdom
| | - Iain G Johnston
- Faculty of Mathematics and Natural Sciences, University of Bergen, 5007, Norway
- Alan Turing Institute, London NW1 2DB, United Kingdom
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Johnston IG. Tension and Resolution: Dynamic, Evolving Populations of Organelle Genomes within Plant Cells. MOLECULAR PLANT 2019; 12:764-783. [PMID: 30445187 DOI: 10.1016/j.molp.2018.11.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/25/2018] [Accepted: 11/07/2018] [Indexed: 06/09/2023]
Abstract
Mitochondria and plastids form dynamic, evolving populations physically embedded in the fluctuating environment of the plant cell. Their evolutionary heritage has shaped how the cell controls the genetic structure and the physical behavior of its organelle populations. While the specific genes involved in these processes are gradually being revealed, the governing principles underlying this controlled behavior remain poorly understood. As the genetic and physical dynamics of these organelles are central to bioenergetic performance and plant physiology, this challenges both fundamental biology and strategies to engineer better-performing plants. This article reviews current knowledge of the physical and genetic behavior of mitochondria and chloroplasts in plant cells. An overarching hypothesis is proposed whereby organelles face a tension between genetic robustness and individual control and responsiveness, and different species resolve this tension in different ways. As plants are immobile and thus subject to fluctuating environments, their organelles are proposed to favor individual responsiveness, sacrificing genetic robustness. Several notable features of plant organelles, including large genomes, mtDNA recombination, fragmented organelles, and plastid/mitochondrial differences may potentially be explained by this hypothesis. Finally, the ways that quantitative and systems biology can help shed light on the plethora of open questions in this field are highlighted.
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Affiliation(s)
- Iain G Johnston
- School of Biosciences, University of Birmingham, Birmingham, UK; Birmingham Institute for Forest Research, University of Birmingham, Birmingham, UK.
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Shaari N'AL, Jaoi-Edward M, Loo SS, Salisi MS, Yusoff R, Ab Ghani NI, Saad MZ, Ahmad H. Karyotypic and mtDNA based characterization of Malaysian water buffalo. BMC Genet 2019; 20:37. [PMID: 30909863 PMCID: PMC6434848 DOI: 10.1186/s12863-019-0741-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 03/19/2019] [Indexed: 11/26/2022] Open
Abstract
Background In Malaysia, the domestic water buffaloes (Bubalus bubalis) are classified into the swamp and the murrah buffaloes. Identification of these buffaloes is usually made via their phenotypic appearances. This study characterizes the subspecies of water buffaloes using karyotype, molecular and phylogenetic analyses. Blood of 105 buffaloes, phenotypically identified as swamp, murrah and crossbred buffaloes were cultured, terminated and harvested using conventional karyotype protocol to determine the number of chromosomes. Then, the D-loop of mitochondrial DNA of 10 swamp, 6 crossbred and 4 murrah buffaloes which were identified earlier by karyotyping were used to construct a phylogenetic tree was constructed. Results Karyotypic analysis confirmed that all 93 animals phenotypically identified as swamp buffaloes with 48 chromosomes, all 7 as crossbreds with 49 chromosomes, and all 5 as murrah buffaloes with 50 chromosomes. The D-loop of mitochondrial DNA analysis showed that 10 haplotypes were observed with haplotype diversity of 0.8000 ± 0.089. Sequence characterization revealed 72 variables sites in which 67 were parsimony informative sites with sequence diversity of 0.01906. The swamp and murrah buffaloes clearly formed 2 different clades in the phylogenetic tree, indicating clear maternal divergence from each other. The crossbreds were grouped within the swamp buffalo clade, indicating the dominant maternal swamp buffalo gene in the crossbreds. Conclusion Thus, the karyotyping could be used to differentiate the water buffaloes while genotypic analysis could be used to characterize the water buffaloes and their crossbreds.
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Affiliation(s)
- Nor ' Ammar Liyana Shaari
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Malaysia
| | - Marilyn Jaoi-Edward
- Agro-Biotechnology Institute (ABI), National Institutes of Biotechnology Malaysia (NIBM), c/o MARDI Headquarters, 43400, Serdang, Malaysia
| | - Shu San Loo
- Agro-Biotechnology Institute (ABI), National Institutes of Biotechnology Malaysia (NIBM), c/o MARDI Headquarters, 43400, Serdang, Malaysia
| | - Mohd Shahrom Salisi
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Malaysia
| | - Rosnina Yusoff
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Malaysia
| | - Nurul Izza Ab Ghani
- Department of Biology, Faculty of Science, Universiti Putra Malaysia, 43400, Serdang, Malaysia
| | - Mohd Zamri Saad
- Research Centre for Ruminant Diseases, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Malaysia
| | - Hafandi Ahmad
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Malaysia.
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Pan J, Wang L, Lu C, Zhu Y, Min Z, Dong X, Sha H. Matching Mitochondrial DNA Haplotypes for Circumventing Tissue-Specific Segregation Bias. iScience 2019; 13:371-379. [PMID: 30897510 PMCID: PMC6426714 DOI: 10.1016/j.isci.2019.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/13/2019] [Accepted: 03/01/2019] [Indexed: 02/01/2023] Open
Abstract
Mitochondrial DNA (mtDNA) segregation associated with donor-recipient mtDNA mismatch in mitochondria replacement therapy leads to unknown risks. Here, to explore whether matching mtDNA haplotypes contributes to ameliorating segregation, we reproduced various degrees of heteroplasmic mice with three single nucleotide polymorphisms to monitor segregation severity. “Segregation” presented in tissues of heteroplasmic mice containing low-level donor mtDNA heteroplasmy, and disappeared as donor mtDNA heteroplasmy levels ascended. Meanwhile, we found that distribution of donor mtDNA among the blastomeres of preimplantation embryos from the heteroplasmic mice shared the same tendency as that in adult tissues. Statistical analysis showed that no selective replication of donor mtDNA occurred during lifespan. Tracking donor mtDNA distribution showed that uneven distribution of donor mtDNA among embryonic blastomeres gradually became even as donor mtDNA heteroplasmy increased, indicating that the “segregation” in tissues was inherited from the uneven distribution. Our finding suggested that donor-recipient mtDNA matching could circumvent segregation in mitochondria replacement therapy. Matching mitochondrial DNA haplotypes make the nucleus treat different mtDNA the same Similar mtDNA haplotypes prevents tissue-specific segregation bias Low level of mtDNA heteroplasmy results in uneven inheritance rather than segregation
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Affiliation(s)
- Jianxin Pan
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Li Wang
- Key Lab of Synthetic Biology of CAS, Shanghai Institute for Biological Sciences, Shanghai Research Center of Biotech., Chinese Academy of Sciences, 500 Caobao Road, Shanghai 200233, China
| | - Charles Lu
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China; Washington University in St. Louis, Saint Louis 63110, USA
| | - Yanming Zhu
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Zhunyuan Min
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Xi Dong
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China.
| | - Hongying Sha
- Reproductive Medicine Center, Zhongshan Hospital, State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai 200032, China.
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Dobler R, Dowling DK, Morrow EH, Reinhardt K. A systematic review and meta-analysis reveals pervasive effects of germline mitochondrial replacement on components of health. Hum Reprod Update 2019; 24:519-534. [PMID: 29757366 DOI: 10.1093/humupd/dmy018] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 05/03/2018] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Mitochondrial replacement, a form of nuclear transfer, has been proposed as a germline therapy to prevent the transmission of mitochondrial diseases. Mitochondrial replacement therapy has been licensed for clinical application in the UK, and already carried out in other countries, but little is known about negative or unintended effects on the health of offspring born using this technique. OBJECTIVE AND RATIONALE Studies in invertebrate models have used techniques that achieve mitochondrial replacement to create offspring with novel combinations of mitochondrial and nuclear genotype. These have demonstrated that the creation of novel mitochondrial-nuclear interactions can lead to alterations in offspring characteristics, such as development rates, fertility and longevity. However, it is currently unclear whether such interactions could similarly affect the outcomes of vertebrate biomedical studies, which have sought to assess the efficacy of the replacement therapy. SEARCH METHODS This systematic review addresses whether the effects of mitochondrial replacement on offspring characteristics differ in magnitude between biological (conducted on invertebrate models, with an ecological or evolutionary focus) and biomedical studies (conducted on vertebrate models, with a clinical focus). Studies were selected based on a key-word search in 'Web of Science', complemented by backward searches of reviews on the topic of mitochondrial-nuclear (mito-nuclear) interactions. In total, 43 of the resulting 116 publications identified in the search contained reliable data to estimate effect sizes of mitochondrial replacement. We found no evidence of publication bias when examining effect-size estimates across sample sizes. OUTCOMES Mitochondrial replacement consistently altered the phenotype, with significant effects at several levels of organismal performance and health, including gene expression, anatomy, metabolism and life-history. Biomedical and biological studies, while differing in the methods used to achieve mitochondrial replacement, showed only marginally significant differences in effect-size estimates (-0.233 [CI: -0.495 to -0.011]), with larger effect-size estimates in biomedical studies (0.697 [CI: 0.450-0.956]) than biological studies (0.462 [CI: 0.287-0.688]). Humans showed stronger effects than other species. Effects of mitochondrial replacement were also stronger in species with a higher basal metabolic rate. Based on our results, we conducted the first formal risk analysis of mitochondrial replacement, and conservatively estimate negative effects in at least one in every 130 resulting offspring born to the therapy. WIDER IMPLICATIONS Our findings suggest that mitochondrial replacement may routinely affect offspring characteristics across a wide array of animal species, and that such effects are likely to extend to humans. Studies in invertebrate models have confirmed mito-nuclear interactions as the underpinning cause of organismal effects following mitochondrial replacement. This therefore suggests that mito-nuclear interactions are also likely to be contributing to effects seen in biomedical studies, on vertebrate models, whose effect sizes exceeded those of biological studies. Our results advocate the use of safeguards that could offset any negative effects (defining any unintended effect as being negative) mediated by mito-nuclear interactions following mitochondrial replacement in humans, such as mitochondrial genetic matching between donor and recipient. Our results also suggest that further research into the molecular nature of mito-nuclear interactions would be beneficial in refining the clinical application of mitochondrial replacement, and in establishing what degree of variation between donor and patient mitochondrial DNA haplotypes is acceptable to ensure 'haplotype matching'.
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Affiliation(s)
- Ralph Dobler
- Applied Zoology, Technische Universität Dresden, Zellescher Weg 20b, Dresden, Germany
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Vic., Australia
| | - Edward H Morrow
- Evolution, Behaviour and Environment Group, School of Life Sciences, University of Sussex, Brighton, UK
| | - Klaus Reinhardt
- Applied Zoology, Technische Universität Dresden, Zellescher Weg 20b, Dresden, Germany
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Gohel D, Sripada L, Prajapati P, Singh K, Roy M, Kotadia D, Tassone F, Charlet-Berguerand N, Singh R. FMRpolyG alters mitochondrial transcripts level and respiratory chain complex assembly in Fragile X associated tremor/ataxia syndrome [FXTAS]. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1379-1388. [PMID: 30771487 DOI: 10.1016/j.bbadis.2019.02.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 02/06/2019] [Accepted: 02/11/2019] [Indexed: 12/20/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an inherited neurodegenerative disorder caused by an expansion of 55 to 200 CGG repeats (premutation) in FMR1. These CGG repeats are Repeat Associated non-ATG (RAN) translated into a small and pathogenic protein, FMRpolyG. The cellular and molecular mechanisms of FMRpolyG toxicity are unclear. Various mitochondrial dysfunctions have been observed in FXTAS patients and animal models. However, the causes of these mitochondrial alterations are not well understood. In the current study, we investigated interaction of FMRpolyG with mitochondria and its role in modulating mitochondrial functions. Beside nuclear inclusions, FMRpolyG also formed small cytosolic aggregates that interact with mitochondria both in cell and mouse model of FXTAS. Importantly, expression of FMRpolyG reduces ATP levels, mitochondrial transmembrane potential, mitochondrial supercomplexes assemblies and activities and expression of mitochondrial DNA encoded transcripts in cell and animal model of FXTAS, as well as in FXTAS patient brain tissues. Overall, these results suggest that FMRpolyG alters mitochondrial functions, bioenergetics and initiates cell death. The further study in this direction will help to establish the role of mitochondria in FXTAS conditions.
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Affiliation(s)
- Dhruv Gohel
- Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390002, Gujarat, India
| | - Lakshmi Sripada
- Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390002, Gujarat, India
| | - Paresh Prajapati
- SCoBIRC Department of Neuroscience, University of Kentucky, 741S. Limestone, BBSRB, Lexington, KY 40536, USA
| | - Kritarth Singh
- Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390002, Gujarat, India
| | - Milton Roy
- Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390002, Gujarat, India
| | - Darshan Kotadia
- Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390002, Gujarat, India
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Davis, CA 95817, USA
| | - Nicolas Charlet-Berguerand
- Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, Université of Strasbourg, 67400 Illkirch, France
| | - Rajesh Singh
- Department of Biochemistry, Faculty of Science, The M.S. University of Baroda, Vadodara 390002, Gujarat, India.
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Abstract
Cell-to-cell heterogeneity drives a range of (patho)physiologically important phenomena, such as cell fate and chemotherapeutic resistance. The role of metabolism, and particularly of mitochondria, is increasingly being recognized as an important explanatory factor in cell-to-cell heterogeneity. Most eukaryotic cells possess a population of mitochondria, in the sense that mitochondrial DNA (mtDNA) is held in multiple copies per cell, where the sequence of each molecule can vary. Hence, intra-cellular mitochondrial heterogeneity is possible, which can induce inter-cellular mitochondrial heterogeneity, and may drive aspects of cellular noise. In this review, we discuss sources of mitochondrial heterogeneity (variations between mitochondria in the same cell, and mitochondrial variations between supposedly identical cells) from both genetic and non-genetic perspectives, and mitochondrial genotype-phenotype links. We discuss the apparent homeostasis of mtDNA copy number, the observation of pervasive intra-cellular mtDNA mutation (which is termed "microheteroplasmy"), and developments in the understanding of inter-cellular mtDNA mutation ("macroheteroplasmy"). We point to the relationship between mitochondrial supercomplexes, cristal structure, pH, and cardiolipin as a potential amplifier of the mitochondrial genotype-phenotype link. We also discuss mitochondrial membrane potential and networks as sources of mitochondrial heterogeneity, and their influence upon the mitochondrial genome. Finally, we revisit the idea of mitochondrial complementation as a means of dampening mitochondrial genotype-phenotype links in light of recent experimental developments. The diverse sources of mitochondrial heterogeneity, as well as their increasingly recognized role in contributing to cellular heterogeneity, highlights the need for future single-cell mitochondrial measurements in the context of cellular noise studies.
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Affiliation(s)
- Juvid Aryaman
- Department of Mathematics, Imperial College London, London, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Iain G. Johnston
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
- EPSRC Centre for the Mathematics of Precision Healthcare, Imperial College London, London, United Kingdom
| | - Nick S. Jones
- Department of Mathematics, Imperial College London, London, United Kingdom
- EPSRC Centre for the Mathematics of Precision Healthcare, Imperial College London, London, United Kingdom
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Hahn A, Zuryn S. The Cellular Mitochondrial Genome Landscape in Disease. Trends Cell Biol 2018; 29:227-240. [PMID: 30509558 DOI: 10.1016/j.tcb.2018.11.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 11/06/2018] [Accepted: 11/09/2018] [Indexed: 12/18/2022]
Abstract
Mitochondrial genome (mitochondrial DNA, mtDNA) lesions that unbalance bioenergetic and oxidative outputs are an important cause of human disease. A major impediment in our understanding of the pathophysiology of mitochondrial disorders is the complexity with which mtDNA mutations are spatiotemporally distributed and managed within individual cells, tissues, and organs. Unlike the comparatively static nuclear genome, accumulating evidence highlights the variability, dynamism, and modifiability of the mtDNA nucleotide sequence between individual cells over time. In this review, we summarize and discuss the impact of mtDNA defects on disease within the context of a mosaic and shifting mutational landscape.
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Affiliation(s)
- Anne Hahn
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Australia
| | - Steven Zuryn
- The University of Queensland, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, Brisbane, Australia.
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Nicholls TJ, Gustafsson CM. Separating and Segregating the Human Mitochondrial Genome. Trends Biochem Sci 2018; 43:869-881. [PMID: 30224181 DOI: 10.1016/j.tibs.2018.08.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/21/2018] [Accepted: 08/22/2018] [Indexed: 12/17/2022]
Abstract
Cells contain thousands of copies of the mitochondrial genome. These genomes are distributed within the tubular mitochondrial network, which is itself spread across the cytosol of the cell. Mitochondrial DNA (mtDNA) replication occurs throughout the cell cycle and ensures that cells maintain a sufficient number of mtDNA copies. At replication termination the genomes must be resolved and segregated within the mitochondrial network. Defects in mtDNA replication and segregation are a cause of human mitochondrial disease associated with failure of cellular energy production. This review focuses upon recent developments on how mitochondrial genomes are physically separated at the end of DNA replication, and how these genomes are subsequently segregated and distributed around the mitochondrial network.
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Affiliation(s)
- Thomas J Nicholls
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, SE-405 30 Gothenburg, Sweden.
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, SE-405 30 Gothenburg, Sweden
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Burgstaller JP, Kolbe T, Havlicek V, Hembach S, Poulton J, Piálek J, Steinborn R, Rülicke T, Brem G, Jones NS, Johnston IG. Large-scale genetic analysis reveals mammalian mtDNA heteroplasmy dynamics and variance increase through lifetimes and generations. Nat Commun 2018; 9:2488. [PMID: 29950599 PMCID: PMC6021422 DOI: 10.1038/s41467-018-04797-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 05/22/2018] [Indexed: 11/30/2022] Open
Abstract
Vital mitochondrial DNA (mtDNA) populations exist in cells and may consist of heteroplasmic mixtures of mtDNA types. The evolution of these heteroplasmic populations through development, ageing, and generations is central to genetic diseases, but is poorly understood in mammals. Here we dissect these population dynamics using a dataset of unprecedented size and temporal span, comprising 1947 single-cell oocyte and 899 somatic measurements of heteroplasmy change throughout lifetimes and generations in two genetically distinct mouse models. We provide a novel and detailed quantitative characterisation of the linear increase in heteroplasmy variance throughout mammalian life courses in oocytes and pups. We find that differences in mean heteroplasmy are induced between generations, and the heteroplasmy of germline and somatic precursors diverge early in development, with a haplotype-specific direction of segregation. We develop stochastic theory predicting the implications of these dynamics for ageing and disease manifestation and discuss its application to human mtDNA dynamics.
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Affiliation(s)
- Joerg P Burgstaller
- Department for Agrobiotechnology, Biotechnology in Animal Production, IFA Tulln, 3430, Tulln, Austria.
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria.
- Department of Mathematics, Imperial College London, London, SW7 2AZ, UK.
| | - Thomas Kolbe
- Biomodels Austria, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210, Vienna, Austria
- University of Natural Resources and Life Sciences, Konrad Lorenz Strasse 20, 3430, Tulln, Austria
| | - Vitezslav Havlicek
- Department for Biomedical Sciences, Reproduction Centre Wieselburg, University of Veterinary Medicine, Vienna, Austria
| | - Stephanie Hembach
- Department for Agrobiotechnology, Biotechnology in Animal Production, IFA Tulln, 3430, Tulln, Austria
| | - Joanna Poulton
- Nuffield Department of Women's and Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Jaroslav Piálek
- Research Facility Studenec, Institute of Vertebrate Biology of the Czech Academy of Sciences, Květná 8, 603 65, Brno, Czech Republic
| | - Ralf Steinborn
- Genomics Core Facility, VetCore, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria
| | - Thomas Rülicke
- Institute of Laboratory Animal Science, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria
| | - Gottfried Brem
- Department for Agrobiotechnology, Biotechnology in Animal Production, IFA Tulln, 3430, Tulln, Austria
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210, Vienna, Austria
| | - Nick S Jones
- Department of Mathematics, Imperial College London, London, SW7 2AZ, UK.
- EPSRC Centre for the Mathematics of Precision Healthcare, Imperial College London, London, SW7 2AZ, UK.
| | - Iain G Johnston
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
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43
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Poulton J, Finsterer J, Yu-Wai-Man P. Genetic Counselling for Maternally Inherited Mitochondrial Disorders. Mol Diagn Ther 2018; 21:419-429. [PMID: 28536827 DOI: 10.1007/s40291-017-0279-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The aim of this review was to provide an evidence-based approach to frequently asked questions relating to the risk of transmitting a maternally inherited mitochondrial disorder (MID). We do not address disorders linked with disturbed mitochondrial DNA (mtDNA) maintenance, causing mtDNA depletion or multiple mtDNA deletions, as these are autosomally inherited. The review addresses questions regarding prognosis, recurrence risks and the strategies available to prevent disease transmission. The clinical and genetic complexity of maternally inherited MIDs represent a major challenge for patients, their relatives and health professionals. Since many of the genetic and pathophysiological aspects of MIDs remain unknown, counselling of affected patients and at-risk family members remains difficult. MtDNA mutations are maternally transmitted or, more rarely, they are sporadic, occurring de novo (~25%). Females carrying homoplasmic mtDNA mutations will transmit the mutant species to all of their offspring, who may or may not exhibit a similar phenotype depending on modifying, secondary factors. Females carrying heteroplasmic mtDNA mutations will transmit a variable amount of mutant mtDNA to their offspring, which can result in considerable phenotypic heterogeneity among siblings. The majority of mtDNA rearrangements, such as single large-scale deletions, are sporadic, but there is a small risk of recurrence (~4%) among the offspring of affected women. The range and suitability of reproductive choices for prospective mothers is a complex area of mitochondrial medicine that needs to be managed by experienced healthcare professionals as part of a multidisciplinary team. Genetic counselling is facilitated by the identification of the underlying causative genetic defect. To provide more precise genetic counselling, further research is needed to clarify the secondary factors that account for the variable penetrance and the often marked differential expressivity of pathogenic mtDNA mutations both within and between families.
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Affiliation(s)
- Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Josef Finsterer
- Krankenanstalt Rudolfstiftung, Postfach 20, 1180, Vienna, Austria.
| | - Patrick Yu-Wai-Man
- Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.,Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle upon Tyne, UK.,NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
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44
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Craven L, Tang MX, Gorman GS, De Sutter P, Heindryckx B. Novel reproductive technologies to prevent mitochondrial disease. Hum Reprod Update 2018. [PMID: 28651360 DOI: 10.1093/humupd/dmx018] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The use of nuclear transfer (NT) has been proposed as a novel reproductive treatment to overcome the transmission of maternally-inherited mitochondrial DNA (mtDNA) mutations. Pathogenic mutations in mtDNA can cause a wide-spectrum of life-limiting disorders, collectively known as mtDNA disease, for which there are currently few effective treatments and no known cures. The many unique features of mtDNA make genetic counselling challenging for women harbouring pathogenic mtDNA mutations but reproductive options that involve medical intervention are available that will minimize the risk of mtDNA disease in their offspring. This includes PGD, which is currently offered as a clinical treatment but will not be suitable for all. The potential for NT to reduce transmission of mtDNA mutations has been demonstrated in both animal and human models, and has recently been clinically applied not only to prevent mtDNA disease but also for some infertility cases. In this review, we will interrogate the different NT techniques, including a discussion on the available safety and efficacy data of these technologies for mtDNA disease prevention. In addition, we appraise the evidence for the translational use of NT technologies in infertility. OBJECTIVE AND RATIONALE We propose to review the current scientific evidence regarding the clinical use of NT to prevent mitochondrial disease. SEARCH METHODS The scientific literature was investigated by searching PubMed database until Jan 2017. Relevant documents from Human Fertilisation and Embryology Authority as well as reports from both the scientific and popular media were also implemented. The above searches were based on the following key words: 'mitochondria', 'mitochondrial DNA'; 'mitochondrial DNA disease', 'fertility'; 'preimplantation genetic diagnosis', 'nuclear transfer', 'mitochondrial replacement' and 'mitochondrial donation'. OUTCOMES While NT techniques have been shown to effectively reduce the transmission of heteroplasmic mtDNA variants in animal models, and increasing evidence supports their use to prevent the transmission of human mtDNA disease, the need for robust, long-term evaluation is still warranted. Moreover, prenatal screening would still be strongly advocated in combination with the use of these IVF-based technologies. Scientific evidence to support the use of NT and other novel reproductive techniques for infertility is currently lacking. WIDER IMPLICATIONS It is mandatory that any new ART treatments are first adequately assessed in both animal and human models before the cautious implementation of these new therapeutic approaches is clinically undertaken. There is growing evidence to suggest that the translation of these innovative technologies into clinical practice should be cautiously adopted only in highly selected patients. Indeed, given the limited safety and efficacy data, close monitoring of any offspring remains paramount.
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Affiliation(s)
- Lyndsey Craven
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Mao-Xing Tang
- Ghent-Fertility and Stem Cell Team (G-FaST), Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Petra De Sutter
- Ghent-Fertility and Stem Cell Team (G-FaST), Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Björn Heindryckx
- Ghent-Fertility and Stem Cell Team (G-FaST), Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
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Burr SP, Pezet M, Chinnery PF. Mitochondrial DNA Heteroplasmy and Purifying Selection in the Mammalian Female Germ Line. Dev Growth Differ 2018; 60:21-32. [PMID: 29363102 DOI: 10.1111/dgd.12420] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 12/08/2017] [Indexed: 01/19/2023]
Abstract
Inherited mutations in the mitochondrial (mt)DNA are a major cause of human disease, with approximately 1 in 5000 people affected by one of the hundreds of identified pathogenic mtDNA point mutations or deletions. Due to the severe, and often untreatable, symptoms of many mitochondrial diseases, identifying how these mutations are inherited from one generation to the next has been an area of intense research in recent years. Despite large advances in our understanding of this complex process, many questions remain unanswered, with one of the most hotly debated being whether or not purifying selection acts against pathogenic mutations during germline development.
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Affiliation(s)
- Stephen P Burr
- MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Mikael Pezet
- MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Patrick F Chinnery
- MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
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46
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A Population Phylogenetic View of Mitochondrial Heteroplasmy. Genetics 2018; 208:1261-1274. [PMID: 29343499 DOI: 10.1534/genetics.118.300711] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/12/2018] [Indexed: 11/18/2022] Open
Abstract
The mitochondrion has recently emerged as an active player in myriad cellular processes. Additionally, it was recently shown that >200 diseases are known to be linked to variants in mitochondrial DNA or in nuclear genes interacting with mitochondria. This has reinvigorated interest in its biology and population genetics. Mitochondrial heteroplasmy, or genotypic variation of mitochondria within an individual, is now understood to be common in humans and important in human health. However, it is still not possible to make quantitative predictions about the inheritance of heteroplasmy and its proliferation within the body, partly due to the lack of an appropriate model. Here, we present a population-genetic framework for modeling mitochondrial heteroplasmy as a process that occurs on an ontogenetic phylogeny, with genetic drift and mutation changing heteroplasmy frequencies during the various developmental processes represented in the phylogeny. Using this framework, we develop a Bayesian inference method for inferring rates of mitochondrial genetic drift and mutation at different stages of human life. Applying the method to previously published heteroplasmy frequency data, we demonstrate a severe effective germline bottleneck comprised of the cumulative genetic drift occurring between the divergence of germline and somatic cells in the mother, and the separation of germ layers in the offspring. Additionally, we find that the two somatic tissues we analyze here undergo tissue-specific bottlenecks during embryogenesis, less severe than the effective germline bottleneck, and that these somatic tissues experience little additional genetic drift during adulthood. We conclude with a discussion of possible extensions of the ontogenetic phylogeny framework and its possible applications to other ontogenetic processes in addition to mitochondrial heteroplasmy.
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47
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Lima A, Burgstaller J, Sanchez-Nieto JM, Rodríguez TA. The Mitochondria and the Regulation of Cell Fitness During Early Mammalian Development. Curr Top Dev Biol 2017; 128:339-363. [PMID: 29477168 DOI: 10.1016/bs.ctdb.2017.10.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
From fertilization until the onset of gastrulation the early mammalian embryo undergoes a dramatic series of changes that converts a single fertilized cell into a remarkably complex organism. Much attention has been given to the molecular changes occurring during this process, but here we will review what is known about the changes affecting the mitochondria and how they impact on the energy metabolism and apoptotic response of the embryo. We will also focus on understanding what quality control mechanisms ensure optimal mitochondrial activity in the embryo, and in this way provide an overview of the importance of the mitochondria in determining cell fitness during early mammalian development.
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Affiliation(s)
- Ana Lima
- British Heart Foundation Centre for Research Excellence, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London, United Kingdom; Cell Stress Group, MRC London Institute of Medical Sciences (LMS), London, United Kingdom
| | - Jörg Burgstaller
- British Heart Foundation Centre for Research Excellence, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London, United Kingdom; Biotechnology in Animal Production, Department for Agrobiotechnology, IFA Tulln, Tulln, Austria
| | - Juan M Sanchez-Nieto
- British Heart Foundation Centre for Research Excellence, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London, United Kingdom
| | - Tristan A Rodríguez
- British Heart Foundation Centre for Research Excellence, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London, United Kingdom.
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48
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Radzvilavicius AL, Lane N, Pomiankowski A. Sexual conflict explains the extraordinary diversity of mechanisms regulating mitochondrial inheritance. BMC Biol 2017; 15:94. [PMID: 29073898 PMCID: PMC5658935 DOI: 10.1186/s12915-017-0437-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/10/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Mitochondria are predominantly inherited from the maternal gamete, even in unicellular organisms. Yet an extraordinary array of mechanisms enforce uniparental inheritance, which implies shifting selection pressures and multiple origins. RESULTS We consider how this high turnover in mechanisms controlling uniparental inheritance arises using a novel evolutionary model in which control of mitochondrial transmission occurs either during spermatogenesis (by paternal nuclear genes) or at/after fertilization (by maternal nuclear genes). The model treats paternal leakage as an evolvable trait. Our evolutionary analysis shows that maternal control consistently favours strict uniparental inheritance with complete exclusion of sperm mitochondria, whereas some degree of paternal leakage of mitochondria is an expected outcome under paternal control. This difference arises because mito-nuclear linkage builds up with maternal control, allowing the greater variance created by asymmetric inheritance to boost the efficiency of purifying selection and bring benefits in the long term. In contrast, under paternal control, mito-nuclear linkage tends to be much weaker, giving greater advantage to the mixing of cytotypes, which improves mean fitness in the short term, even though it imposes a fitness cost to both mating types in the long term. CONCLUSIONS Sexual conflict is an inevitable outcome when there is competition between maternal and paternal control of mitochondrial inheritance. If evolution has led to complete uniparental inheritance through maternal control, it creates selective pressure on the paternal nucleus in favour of subversion through paternal leakage, and vice versa. This selective divergence provides a reason for the repeated evolution of novel mechanisms that regulate the transmission of paternal mitochondria, both in the fertilized egg and spermatogenesis. Our analysis suggests that the widespread occurrence of paternal leakage and prevalence of heteroplasmy are natural outcomes of this sexual conflict.
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Affiliation(s)
- Arunas L Radzvilavicius
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology, University College London, Gower Street, London, WC1E 6BT, UK
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Nick Lane
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology, University College London, Gower Street, London, WC1E 6BT, UK
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | - Andrew Pomiankowski
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology, University College London, Gower Street, London, WC1E 6BT, UK.
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK.
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Melvin RG, Ballard JWO. Cellular and population level processes influence the rate, accumulation and observed frequency of inherited and somatic mtDNA mutations. Mutagenesis 2017; 32:323-334. [PMID: 28521046 DOI: 10.1093/mutage/gex004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mitochondria are found in all animals and have the unique feature of containing multiple copies of their own small, circular DNA genome (mtDNA). The rate and pattern of mutation accumulation in the mtDNA are influenced by molecular, cellular and population level processes. We distinguish between inherited and somatic mtDNA mutations and review evidence for the often-made assumption that mutations accumulate at a higher rate in mtDNA than in nuclear DNA (nDNA). We conclude that the whole genome mutation accumulation rate is higher for mtDNA than for nDNA but include the caveat that rates overlap considerably between the individual mtDNA- and nDNA-encoded genes. Next, we discuss the postulated causal mechanisms for the high rate of mtDNA mutation accumulation in both inheritance and in somatic cells. Perhaps unexpectedly, mtDNA is resilient to many mutagens of nDNA but is prone to errors of replication. We then consider the influence of maternal inheritance, recombination and selection on the observed accumulation pattern of inherited mtDNA mutations. Finally, we discuss environmental influences of temperature and diet on the observed frequency of inherited and somatic mtDNA mutations. We conclude that it is necessary to understand the cellular processes to fully interpret the pattern of mutations and how they influence our interpretations of evolution and disease.
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Affiliation(s)
- Richard G Melvin
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - John William O Ballard
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
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50
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Modulating mitochondrial quality in disease transmission: towards enabling mitochondrial DNA disease carriers to have healthy children. Biochem Soc Trans 2017; 44:1091-100. [PMID: 27528757 PMCID: PMC4984448 DOI: 10.1042/bst20160095] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Indexed: 12/19/2022]
Abstract
One in 400 people has a maternally inherited mutation in mtDNA potentially causing incurable disease. In so-called heteroplasmic disease, mutant and normal mtDNA co-exist in the cells of carrier women. Disease severity depends on the proportion of inherited abnormal mtDNA molecules. Families who have had a child die of severe, maternally inherited mtDNA disease need reliable information on the risk of recurrence in future pregnancies. However, prenatal diagnosis and even estimates of risk are fraught with uncertainty because of the complex and stochastic dynamics of heteroplasmy. These complications include an mtDNA bottleneck, whereby hard-to-predict fluctuations in the proportions of mutant and normal mtDNA may arise between generations. In ‘mitochondrial replacement therapy’ (MRT), damaged mitochondria are replaced with healthy ones in early human development, using nuclear transfer. We are developing non-invasive alternatives, notably activating autophagy, a cellular quality control mechanism, in which damaged cellular components are engulfed by autophagosomes. This approach could be used in combination with MRT or with the regular management, pre-implantation genetic diagnosis (PGD). Mathematical theory, supported by recent experiments, suggests that this strategy may be fruitful in controlling heteroplasmy. Using mice that are transgenic for fluorescent LC3 (the hallmark of autophagy) we quantified autophagosomes in cleavage stage embryos. We confirmed that the autophagosome count peaks in four-cell embryos and this correlates with a drop in the mtDNA content of the whole embryo. This suggests removal by mitophagy (mitochondria-specific autophagy). We suggest that modulating heteroplasmy by activating mitophagy may be a useful complement to mitochondrial replacement therapy.
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