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Arbeithuber B, Cremona MA, Hester J, Barrett A, Higgins B, Anthony K, Chiaromonte F, Diaz FJ, Makova KD. Advanced age increases frequencies of de novo mitochondrial mutations in macaque oocytes and somatic tissues. Proc Natl Acad Sci U S A 2022; 119:e2118740119. [PMID: 35394879 PMCID: PMC9169796 DOI: 10.1073/pnas.2118740119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/25/2022] [Indexed: 12/18/2022] Open
Abstract
Mutations in mitochondrial DNA (mtDNA) contribute to multiple diseases. However, how new mtDNA mutations arise and accumulate with age remains understudied because of the high error rates of current sequencing technologies. Duplex sequencing reduces error rates by several orders of magnitude via independently tagging and analyzing each of the two template DNA strands. Here, using duplex sequencing, we obtained high-quality mtDNA sequences for somatic tissues (liver and skeletal muscle) and single oocytes of 30 unrelated rhesus macaques, from 1 to 23 y of age. Sequencing single oocytes minimized effects of natural selection on germline mutations. In total, we identified 17,637 tissue-specific de novo mutations. Their frequency increased ∼3.5-fold in liver and ∼2.8-fold in muscle over the ∼20 y assessed. Mutation frequency in oocytes increased ∼2.5-fold until the age of 9 y, but did not increase after that, suggesting that oocytes of older animals maintain the quality of their mtDNA. We found the light-strand origin of replication (OriL) to be a hotspot for mutation accumulation with aging in liver. Indeed, the 33-nucleotide-long OriL harbored 12 variant hotspots, 10 of which likely disrupt its hairpin structure and affect replication efficiency. Moreover, in somatic tissues, protein-coding variants were subject to positive selection (potentially mitigating toxic effects of mitochondrial activity), the strength of which increased with the number of macaques harboring variants. Our work illuminates the origins and accumulation of somatic and germline mtDNA mutations with aging in primates and has implications for delayed reproduction in modern human societies.
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Affiliation(s)
- Barbara Arbeithuber
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
- Experimental Gynaecology, Obstetrics and Gynaecological Endocrinology, Kepler University Hospital Linz, Johannes Kepler University Linz, 4020 Linz, Austria
| | - Marzia A. Cremona
- Department of Operations and Decision Systems, Université Laval, Québec, QC G1V0A6, Canada
- Population Health and Optimal Health Practices, CHU de Québec - Université Laval Research Center, Québec, QC G1V4G2, Canada
- Center for Medical Genomics, The Pennsylvania State University, University Park, PA 16802
| | - James Hester
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
| | - Alison Barrett
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
| | - Bonnie Higgins
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
| | - Kate Anthony
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
| | - Francesca Chiaromonte
- Center for Medical Genomics, The Pennsylvania State University, University Park, PA 16802
- Department of Statistics, The Pennsylvania State University, University Park, PA 16802
- Institute of Economics and EMbeDS, Sant'Anna School of Advanced Studies, Pisa 56127, Italy
| | - Francisco J. Diaz
- Department of Animal Science, The Pennsylvania State University, University Park, PA 16802
| | - Kateryna D. Makova
- Department of Biology, The Pennsylvania State University, University Park, PA 16802
- Center for Medical Genomics, The Pennsylvania State University, University Park, PA 16802
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Mertens J, Regin M, De Munck N, Deckersberg EC, Belva F, Sermon K, Tournaye H, Blockeel C, Van de Velde H, Spits C. Mitochondrial DNA variants segregate during human preimplantation development into genetically different cell lineages that are maintained postnatally. Hum Mol Genet 2022; 31:3629-3642. [DOI: 10.1093/hmg/ddac059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
Humans present remarkable diversity in their mitochondrial DNA (mtDNA) in terms of variants across individuals as well as across tissues and even cells within one person. We have investigated the timing of the first appearance of this variant-driven mosaicism. For this, we deep-sequenced the mtDNA of 254 oocytes from 85 donors, 158 single blastomeres of 25 day-3 embryos, 17 inner cell mass and trophectoderm samples of 7 day-5 blastocysts, 142 bulk DNA and 68 single cells of different adult tissues. We found that day-3 embryos present blastomeres that carry variants only detected in that cell, showing that mtDNA mosaicism arises very early in human development. We classified the mtDNA variants based on their recurrence or uniqueness across different samples. Recurring variants had higher heteroplasmic loads and more frequently resulted in synonymous changes or were located in non-coding regions than variants unique to one oocyte or single embryonic cell. These differences were maintained through development, suggesting that the mtDNA mosaicism arising in the embryo is maintained into adulthood. We observed a decline in potentially pathogenic variants between day-3 and day-5 of development, suggesting early selection. We propose a model in which closely clustered mitochondria carrying specific mtDNA variants in the ooplasm are asymmetrically distributed throughout the cell divisions of the preimplantation embryo, resulting in the earliest form of mtDNA mosaicism in human development.
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Affiliation(s)
- Joke Mertens
- Research Group Reproduction and Genetics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
| | - Marius Regin
- Research Group Reproduction and Genetics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
| | - Neelke De Munck
- (Brussels IVF) Center for Reproductive Medicine, Universitair Ziekenhuis Brussel, 1090 Brussels, Belgium
| | - Edouard Couvreu Deckersberg
- Research Group Reproduction and Genetics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
| | - Florence Belva
- Center for Medical Genetics, Universitair Ziekenhuis Brussel, 1090 Brussels, Belgium
| | - Karen Sermon
- Research Group Reproduction and Genetics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
| | - Herman Tournaye
- (Brussels IVF) Center for Reproductive Medicine, Universitair Ziekenhuis Brussel, 1090 Brussels, Belgium
- Research Group Biology of the testis, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
- Department of Obstetrics, Gynaecology, Perinatology and Reproduction, Institute of Professional Education, Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation, Trubetskaya str., 8, b. 2, 119992, Moscow
| | - Christophe Blockeel
- (Brussels IVF) Center for Reproductive Medicine, Universitair Ziekenhuis Brussel, 1090 Brussels, Belgium
| | - Hilde Van de Velde
- Research Group Reproduction and Genetics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
- (Brussels IVF) Center for Reproductive Medicine, Universitair Ziekenhuis Brussel, 1090 Brussels, Belgium
- Research Group Reproduction and Immunology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
| | - Claudia Spits
- Research Group Reproduction and Genetics, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel (VUB), 1090 Brussels, Belgium
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Arbeithuber B, Hester J, Cremona MA, Stoler N, Zaidi A, Higgins B, Anthony K, Chiaromonte F, Diaz FJ, Makova KD. Age-related accumulation of de novo mitochondrial mutations in mammalian oocytes and somatic tissues. PLoS Biol 2020; 18:e3000745. [PMID: 32667908 PMCID: PMC7363077 DOI: 10.1371/journal.pbio.3000745] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 05/27/2020] [Indexed: 12/21/2022] Open
Abstract
Mutations create genetic variation for other evolutionary forces to operate on and cause numerous genetic diseases. Nevertheless, how de novo mutations arise remains poorly understood. Progress in the area is hindered by the fact that error rates of conventional sequencing technologies (1 in 100 or 1,000 base pairs) are several orders of magnitude higher than de novo mutation rates (1 in 10,000,000 or 100,000,000 base pairs per generation). Moreover, previous analyses of germline de novo mutations examined pedigrees (and not germ cells) and thus were likely affected by selection. Here, we applied highly accurate duplex sequencing to detect low-frequency, de novo mutations in mitochondrial DNA (mtDNA) directly from oocytes and from somatic tissues (brain and muscle) of 36 mice from two independent pedigrees. We found mtDNA mutation frequencies 2- to 3-fold higher in 10-month-old than in 1-month-old mice, demonstrating mutation accumulation during the period of only 9 mo. Mutation frequencies and patterns differed between germline and somatic tissues and among mtDNA regions, suggestive of distinct mutagenesis mechanisms. Additionally, we discovered a more pronounced genetic drift of mitochondrial genetic variants in the germline of older versus younger mice, arguing for mtDNA turnover during oocyte meiotic arrest. Our study deciphered for the first time the intricacies of germline de novo mutagenesis using duplex sequencing directly in oocytes, which provided unprecedented resolution and minimized selection effects present in pedigree studies. Moreover, our work provides important information about the origins and accumulation of mutations with aging/maturation and has implications for delayed reproduction in modern human societies. Furthermore, the duplex sequencing method we optimized for single cells opens avenues for investigating low-frequency mutations in other studies.
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Affiliation(s)
- Barbara Arbeithuber
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - James Hester
- Department of Animal Science, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Marzia A. Cremona
- Department of Statistics, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Nicholas Stoler
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Arslan Zaidi
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Bonnie Higgins
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Kate Anthony
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Francesca Chiaromonte
- Department of Statistics, Pennsylvania State University, University Park, Pennsylvania, United States of America
- EMbeDS, Sant’Anna School of Advanced Studies, Pisa, Italy
| | - Francisco J. Diaz
- Department of Animal Science, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Kateryna D. Makova
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
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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: 39] [Impact Index Per Article: 6.5] [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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De Fanti S, Vicario S, Lang M, Simone D, Magli C, Luiselli D, Gianaroli L, Romeo G. Intra-individual purifying selection on mitochondrial DNA variants during human oogenesis. Hum Reprod 2017; 32:1100-1107. [PMID: 28333293 DOI: 10.1093/humrep/dex051] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 02/27/2017] [Indexed: 11/13/2022] Open
Abstract
STUDY QUESTION Does selection for mtDNA mutations occur in human oocytes? SUMMARY ANSWER We provide statistical evidence in favor of the existence of purifying selection for mtDNA mutations in human oocytes acting between the expulsion of the first and second polar bodies (PBs). WHAT IS KNOWN ALREADY Several lines of evidence in Metazoa, including humans, indicate that variation within the germline of mitochondrial genomes is under purifying selection. The presence of this internal selection filter in the germline has important consequences for the evolutionary trajectory of mtDNA. However, the nature and localization of this internal filter are still unclear while several hypotheses are proposed in the literature. STUDY DESIGN, SIZE, DURATION In this study, 60 mitochondrial genomes were sequenced from 17 sets of oocytes, first and second PBs, and peripheral blood taken from nine women between 38 and 43 years of age. PARTICIPANTS/MATERIALS, SETTING, METHODS Whole genome amplification was performed only on the single cell samples and Sanger sequencing was performed on amplicons. The comparison of variant profiles between first and second PB sequences showed no difference in substitution rates but displayed instead a sharp difference in pathogenicity scores of protein-coding sequences using three different metrics (MutPred, Polyphen and SNPs&GO). MAIN RESULTS AND THE ROLE OF CHANCE Unlike the first, second PBs showed no significant differences in pathogenic scores with blood and oocyte sequences. This suggests that a filtering mechanism for disadvantageous variants operates during oocyte development between the expulsion of the first and second PB. LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION The sample size is small and further studies are needed before this approach can be used in clinical practice. Studies on a model organism would allow the sample size to be increased. WIDER IMPLICATIONS OF THE FINDINGS This work opens the way to the study of the correlation between mtDNA mutations, mitochondrial capacity and viability of oocytes. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by a SISMER grant. Laboratory facilities and skills were freely provided by SISMER, and by the Alma Mater Studiorum, University of Bologna. The authors have no conflict of interest to disclose.
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Affiliation(s)
- Sara De Fanti
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna 40126, Italy
| | - Saverio Vicario
- Institute of Atmospheric Pollution Research, National Research Council, C/O Physics Department, University of Bari 'Aldo Moro', Bari 70132, Italy
| | - Martin Lang
- Medical Genetics Unit, S. Orsola Hospital, University of Bologna, Bologna 40126, Italy.,Current address: Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA
| | - Domenico Simone
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari 'Aldo Moro',Bari70132, Italy
| | - Cristina Magli
- Reproductive Medicine Unit, S.I.S.Me.R., Bologna 40138, Italy
| | - Donata Luiselli
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna 40126, Italy
| | - Luca Gianaroli
- Reproductive Medicine Unit, S.I.S.Me.R., Bologna 40138, Italy
| | - Giovanni Romeo
- Medical Genetics Unit, S. Orsola Hospital, University of Bologna, Bologna 40126, Italy
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Magli MC, De Fanti S, Vicario S, Lang M, Simone D, Luiselli D, Romeo G, Gianaroli L. Reply: Purifying selection on mitochondrial DNA: a strategy for the oocyte to preserve competence. Hum Reprod 2017; 32:1949-1950. [PMID: 28854730 DOI: 10.1093/humrep/dex255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- M Cristina Magli
- Reproductive Medicine Unit, S.I.S.Me.R., Via Mazzini, 12, Bologna 40138, Italy
| | - Sara De Fanti
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via S. Donato, 1, Bologna 40126, Italy
| | - Saverio Vicario
- Institute of Atmospheric Pollution Research, National Research Council, C/O Physics Department, University of Bari 'Aldo Moro', Via G. Amendola, 173, Bari 70132, Italy
| | - Martin Lang
- Medical Genetics Unit, S. Orsola Hospital, University of Bologna, Via Albertoni, 15, Bologna 40126, Italy
| | - Domenico Simone
- Department of Bioscience, Biotechnology and Biopharmaceutics, University of Bari 'Aldo Moro', Via E. Orabona, 4, Bari 70132, Italy
| | - Donata Luiselli
- Department of Biological, Geological and Environmental Sciences, University of Bologna, Via S. Donato, 1, Bologna 40126, Italy
| | - Giovanni Romeo
- Medical Genetics Unit, S. Orsola Hospital, University of Bologna, Via Albertoni, 15, Bologna 40126, Italy
| | - Luca Gianaroli
- Reproductive Medicine Unit, S.I.S.Me.R., Via Mazzini, 12, Bologna 40138, Italy
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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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Abstract
Mitochondrial DNA transfer has recently received attention from physicians. The transfer techniques place genetic material from the egg nucleus of a woman with a mitochondrial DNA mutation into a healthy donated egg from which the nuclear DNA was removed. This technology intends to reconstruct a mitochondria-competent egg to produce a baby. Three approaches: (1) pronuclear transfer; (2) metaphase II spindle transfer (ST); and (3) polar body (PB) transfer, have been proposed and applied in animal models with very low levels of heteroplasmy. Because there is no curative treatment for patients with mitochondrial dysfunction, the UK government has allowed the use of this pioneering technique to prevent the transmission of rare and devastating mitochondrial diseases. Despite general safety in the observation period, this technology involves germline modification, raising scientific and ethical questions in the public. In this review, we focus on this unprecedented technology and discuss its clinical application in the future.
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Affiliation(s)
- Liang Xu
- a Research Center for Translational Medicine , Shanghai East Hospital, Tongji University School of Medicine , Shanghai, China
| | - Rui Shi
- b Department of Obstetrics and Gynecology , Shanghai East Hospital, Tongji University School of Medicine , Shanghai, China
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Richardson J, Irving L, Hyslop LA, Choudhary M, Murdoch A, Turnbull DM, Herbert M. Concise reviews: Assisted reproductive technologies to prevent transmission of mitochondrial DNA disease. Stem Cells 2015; 33:639-45. [PMID: 25377180 PMCID: PMC4359624 DOI: 10.1002/stem.1887] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 09/26/2014] [Accepted: 10/11/2014] [Indexed: 12/31/2022]
Abstract
While the fertilized egg inherits its nuclear DNA from both parents, the mitochondrial DNA is strictly maternally inherited. Cells contain multiple copies of mtDNA, each of which encodes 37 genes, which are essential for energy production by oxidative phosphorylation. Mutations can be present in all, or only in some copies of mtDNA. If present above a certain threshold, pathogenic mtDNA mutations can cause a range of debilitating and fatal diseases. Here, we provide an update of currently available options and new techniques under development to reduce the risk of transmitting mtDNA disease from mother to child. Preimplantation genetic diagnosis (PGD), a commonly used technique to detect mutations in nuclear DNA, is currently being offered to determine the mutation load of embryos produced by women who carry mtDNA mutations. The available evidence indicates that cells removed from an eight-cell embryo are predictive of the mutation load in the entire embryo, indicating that PGD provides an effective risk reduction strategy for women who produce embryos with low mutation loads. For those who do not, research is now focused on meiotic nuclear transplantation techniques to uncouple the inheritance of nuclear and mtDNA. These approaches include transplantation of any one of the products or female meiosis (meiosis II spindle, or either of the polar bodies) between oocytes, or the transplantation of pronuclei between fertilized eggs. In all cases, the transferred genetic material arises from a normal meiosis and should therefore, not be confused with cloning. The scientific progress and associated regulatory issues are discussed. Stem Cells2015;33:639–645
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Affiliation(s)
- Jessica Richardson
- Wellcome Trust Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, United Kingdom; Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
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10
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Cellular Heterogeneity in the Level of mtDNA Heteroplasmy in Mouse Embryonic Stem Cells. Cell Rep 2015; 13:1304-1309. [DOI: 10.1016/j.celrep.2015.10.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 08/19/2015] [Accepted: 10/07/2015] [Indexed: 01/19/2023] Open
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11
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Smeets HJ, Sallevelt SC, Dreesen JC, de Die-Smulders CE, de Coo IF. Preventing the transmission of mitochondrial DNA disorders using prenatal or preimplantation genetic diagnosis. Ann N Y Acad Sci 2015; 1350:29-36. [DOI: 10.1111/nyas.12866] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Hubert J.M. Smeets
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
- CARIM School for Cardiovascular Diseases; Maastricht University; Maastricht the Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht the Netherlands
| | - Suzanne C.E.H. Sallevelt
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
- CARIM School for Cardiovascular Diseases; Maastricht University; Maastricht the Netherlands
| | - Jos C.F.M. Dreesen
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
| | - Christine E.M. de Die-Smulders
- Department of Clinical Genetics; Maastricht University Medical Centre; Maastricht the Netherlands
- GROW School for Oncology and Developmental Biology; Maastricht University; Maastricht the Netherlands
| | - Irenaeus F.M. de Coo
- Department of Neurology; Erasmus MC-Sophia Children's Hospital; Rotterdam the Netherlands
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12
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Xu T, Pagadala V, Mueller DM. Understanding structure, function, and mutations in the mitochondrial ATP synthase. MICROBIAL CELL 2015; 2:105-125. [PMID: 25938092 PMCID: PMC4415626 DOI: 10.15698/mic2015.04.197] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mitochondrial ATP synthase is a multimeric enzyme complex with an overall molecular weight of about 600,000 Da. The ATP synthase is a molecular motor composed of two separable parts: F1 and Fo. The F1 portion contains the catalytic sites for ATP synthesis and protrudes into the mitochondrial matrix. Fo forms a proton turbine that is embedded in the inner membrane and connected to the rotor of F1. The flux of protons flowing down a potential gradient powers the rotation of the rotor driving the synthesis of ATP. Thus, the flow of protons though Fo is coupled to the synthesis of ATP. This review will discuss the structure/function relationship in the ATP synthase as determined by biochemical, crystallographic, and genetic studies. An emphasis will be placed on linking the structure/function relationship with understanding how disease causing mutations or putative single nucleotide polymorphisms (SNPs) in genes encoding the subunits of the ATP synthase, will affect the function of the enzyme and the health of the individual. The review will start by summarizing the current understanding of the subunit composition of the enzyme and the role of the subunits followed by a discussion on known mutations and their effect on the activity of the ATP synthase. The review will conclude with a summary of mutations in genes encoding subunits of the ATP synthase that are known to be responsible for human disease, and a brief discussion on SNPs.
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Affiliation(s)
- Ting Xu
- Department of Biochemistry and Molecular Biology, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064
| | - Vijayakanth Pagadala
- Department of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC
| | - David M Mueller
- Department of Biochemistry and Molecular Biology, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064
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Wells D, Kaur K, Grifo J, Glassner M, Taylor JC, Fragouli E, Munne S. Clinical utilisation of a rapid low-pass whole genome sequencing technique for the diagnosis of aneuploidy in human embryos prior to implantation. J Med Genet 2015; 51:553-62. [PMID: 25031024 PMCID: PMC4112454 DOI: 10.1136/jmedgenet-2014-102497] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND The majority of human embryos created using in vitro fertilisation (IVF) techniques are aneuploid. Comprehensive chromosome screening methods, applicable to single cells biopsied from preimplantation embryos, allow reliable identification and transfer of euploid embryos. Recently, randomised trials using such methods have indicated that aneuploidy screening improves IVF success rates. However, the high cost of testing has restricted the availability of this potentially beneficial strategy. This study aimed to harness next-generation sequencing (NGS) technology, with the intention of lowering the costs of preimplantation aneuploidy screening. METHODS Embryo biopsy, whole genome amplification and semiconductor sequencing. RESULTS A rapid (<15 h) NGS protocol was developed, with consumable cost only two-thirds that of the most widely used method for embryo aneuploidy detection. Validation involved blinded analysis of 54 cells from cell lines or biopsies from human embryos. Sensitivity and specificity were 100%. The method was applied clinically, assisting in the selection of euploid embryos in two IVF cycles, producing healthy children in both cases. The NGS approach was also able to reveal specified mutations in the nuclear or mitochondrial genomes in parallel with chromosome assessment. Interestingly, elevated mitochondrial DNA content was associated with aneuploidy (p<0.05), a finding suggestive of a link between mitochondria and chromosomal malsegregation. CONCLUSIONS This study demonstrates that NGS provides highly accurate, low-cost diagnosis of aneuploidy in cells from human preimplantation embryos and is rapid enough to allow testing without embryo cryopreservation. The method described also has the potential to shed light on other aspects of embryo genetics of relevance to health and viability.
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Affiliation(s)
- Dagan Wells
- Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Kulvinder Kaur
- NIHR Oxford Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, Oxford, UK
| | - Jamie Grifo
- New York University Fertility Center, New York, New York, USA
| | | | - Jenny C Taylor
- NIHR Oxford Biomedical Research Centre, Wellcome Trust Centre for Human Genetics, Oxford, UK
| | - Elpida Fragouli
- Reprogenetics UK, Institute of Reproductive Sciences, Oxford, UK
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14
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Steffann J, Monnot S, Bonnefont JP. mtDNA mutations variously impact mtDNA maintenance throughout the human embryofetal development. Clin Genet 2015; 88:416-24. [PMID: 25523230 DOI: 10.1111/cge.12557] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 12/08/2014] [Accepted: 12/16/2014] [Indexed: 12/31/2022]
Abstract
Mitochondria are the largest generator of ATP in the cell. It is therefore expected that energy-requiring processes such as oocyte maturation, early embryonic or fetal development, would be adversely impacted in case of mitochondrial deficiency. Human mitochondrial DNA (mtDNA) mutations constitute a spontaneous model of mitochondrial failure and offer the opportunity to study the consequences of energetic defects over fertility and embryofetal development. This review provides an update on the mtDNA metabolism in the early preimplantation embryo, and compiles data showing the impact of mtDNA mutations over mtDNA segregation. Despite convincing evidences about the essential role of mitochondria in oogenesis and preimplantation development, no correlation between the presence of a mtDNA mutation and fertilization failure, impaired oocyte quality, or embryofetal development arrest was found. In some cases, mutant cells might upregulate their mitochondrial content to overcome the bioenergetic defects induced by mtDNA mutations, and might escape negative selection. Finally we discuss some of the clinical consequences of these observations.
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Affiliation(s)
- J Steffann
- Université Paris-Descartes, Sorbonne Paris Cité, Institut Imagine and INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
| | - S Monnot
- Université Paris-Descartes, Sorbonne Paris Cité, Institut Imagine and INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
| | - J-P Bonnefont
- Université Paris-Descartes, Sorbonne Paris Cité, Institut Imagine and INSERM U1163, Hôpital Necker-Enfants Malades, Paris, France
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15
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De Praeter C, Vanlander A, Vanhaesebrouck P, Smet J, Seneca S, De Sutter P, Van Coster R. Extremely high mutation load of the mitochondrial 8993 T>G mutation in a newborn: implications for prognosis and family planning decisions. Eur J Pediatr 2015; 174:267-70. [PMID: 25009317 DOI: 10.1007/s00431-014-2370-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 06/19/2014] [Accepted: 06/23/2014] [Indexed: 11/29/2022]
Abstract
UNLABELLED The propositus presented with hypotonia, respiratory failure, and seizures in the newborn period and was found to have severe hyperlactacidemia and a hypertrophic heart. He carried a de novo pathogenic mutation (m.8993 T>G) in the gene encoding subunit 6 of the mitochondrial ATP synthase (MTATP6). Although the lactate concentration in serum normalized and the proband recovered after a short period at the neonatal intensive care unit, his ultimate motor and cognitive development was poor. Brain MRI at the age of 6 months showed bilaterally signal abnormalities in the caudate nucleus, putamen, thalamus, and mesencephalon. He died at the age of 9 months. The difficulty in genetic counseling in families with a maternal mitochondrial mutation disorder is emphasized. CONCLUSION Here, we report on a neonate with the m.8993 T>G mutation and emphasize implications of mtDNA disorders on family planning decisions.
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Affiliation(s)
- Claudine De Praeter
- Department of Neonatology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium,
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16
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Assessment of nuclear transfer techniques to prevent the transmission of heritable mitochondrial disorders without compromising embryonic development competence in mice. Mitochondrion 2014; 18:27-33. [PMID: 25229667 DOI: 10.1016/j.mito.2014.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 08/19/2014] [Accepted: 09/08/2014] [Indexed: 12/16/2022]
Abstract
To evaluate and compare mitochondrial DNA (mtDNA) carry-over and embryonic development potential between different nuclear transfer techniques we performed germinal vesicle nuclear transfer (GV NT), metaphase-II spindle-chromosome-complex (MII-SCC) transfer and pronuclear transfer (PNT) in mice. No detectable mtDNA carry-over was seen in most of the reconstructed oocytes and embryos. No significant differences were seen in mtDNA carry-over rate between GV NT (n=20), MII-SCC transfer (0.29 ± 0.63; n=21) and PNT (0.29 ± 0.75; n=25). Blastocyst formation was not compromised after either PNT (88%; n=18) or MII-SCC transfer (86%; n=27). Further analysis of blastomeres from cleaving embryos (n=8) demonstrated undetectable mtDNA carry-over in all but one blastomere. We show that NT in the germ line is potent to prevent transmission of heritable mtDNA disorders with the applicability for patients attempting reproduction.
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17
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Wang T, Sha H, Ji D, Zhang HL, Chen D, Cao Y, Zhu J. Polar body genome transfer for preventing the transmission of inherited mitochondrial diseases. Cell 2014; 157:1591-604. [PMID: 24949971 DOI: 10.1016/j.cell.2014.04.042] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Revised: 03/11/2014] [Accepted: 04/17/2014] [Indexed: 10/25/2022]
Abstract
Inherited mtDNA diseases transmit maternally and cause severe phenotypes. Currently, there is no effective therapy or genetic screens for these diseases; however, nuclear genome transfer between patients' and healthy eggs to replace mutant mtDNAs holds promises. Considering that a polar body contains few mitochondria and shares the same genomic material as an oocyte, we perform polar body transfer to prevent the transmission of mtDNA variants. We compare the effects of different types of germline genome transfer, including spindle-chromosome transfer, pronuclear transfer, and first and second polar body transfer, in mice. Reconstructed embryos support normal fertilization and produce live offspring. Importantly, genetic analysis confirms that the F1 generation from polar body transfer possesses minimal donor mtDNA carryover compared to the F1 generation from other procedures. Moreover, the mtDNA genotype remains stable in F2 progeny after polar body transfer. Our preclinical model demonstrates polar body transfer has great potential to prevent inherited mtDNA diseases.
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Affiliation(s)
- Tian Wang
- State Key Laboratory of Medical Neurobiology, Department of Neurobiology, Institutes of Brain Science, School of Basic Medical Sciences and Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Hongying Sha
- State Key Laboratory of Medical Neurobiology, Department of Neurobiology, Institutes of Brain Science, School of Basic Medical Sciences and Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai 200032, China.
| | - Dongmei Ji
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, the First Hospital Affiliated for Anhui Medical University, Hefei 230022, China
| | - Helen L Zhang
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Dawei Chen
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, the First Hospital Affiliated for Anhui Medical University, Hefei 230022, China
| | - Yunxia Cao
- Center for Reproductive Medicine, Department of Obstetrics and Gynecology, the First Hospital Affiliated for Anhui Medical University, Hefei 230022, China
| | - Jianhong Zhu
- State Key Laboratory of Medical Neurobiology, Department of Neurobiology, Institutes of Brain Science, School of Basic Medical Sciences and Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai 200032, China.
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18
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Heindryckx B, Neupane J, Vandewoestyne M, Christodoulou C, Jackers Y, Gerris J, Van den Abbeel E, Van Coster R, Deforce D, De Sutter P. Mutation-free baby born from a mitochondrial encephalopathy, lactic acidosis and stroke-like syndrome carrier after blastocyst trophectoderm preimplantation genetic diagnosis. Mitochondrion 2014; 18:12-7. [DOI: 10.1016/j.mito.2014.08.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 08/18/2014] [Accepted: 08/18/2014] [Indexed: 01/01/2023]
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19
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Abstract
The objective of the present study was to develop an approach that could assess the chromosomal status and the mitochondrial DNA (mtDNA) content of oocytes and their corresponding polar bodies (PBs) with the goal of obtaining a comparative picture of the segregation process both for nuclear and mtDNA. After Whole Genome Amplification (WGA), sequencing of the whole mitochondrial genome was attempted to analyze the segregation of mutant and wild-type mtDNA during human meiosis. Three triads, composed of oocyte and corresponding PBs, were analyzed and their chromosome status was successfully assessed. The complete mitochondrial genome (mitogenome) was almost entirely sequenced in the oocytes (95.99% compared to 98.43% in blood), while the percentage of sequences obtained in the corresponding PB1 and PB2 was lower (69.70% and 69.04% respectively). The comparison with the mtDNA sequence in blood revealed no changes in the D-loop region for any of the cells of each triad. In the coding region of blood mtDNA and oocyte mtDNA sequences showed full correspondence, whereas all PBs had at least one change with respect to the blood-oocyte pairs. In all, 9 changes were found, either in PB1 or PB2: 4 in MT-ND5, 2 in MT-RNR2, and 1 each in MT-ATP8, MT-ND4, MT-CYTB. The full concordance between oocyte and blood in the 3 triads, and the relegation of changes to PBs, revealed the unexpected coexistence of different variants, giving a refined estimation of mitochondrial heteroplasmy. Should these findings be confirmed by additional data, an active mechanism could be postulated in the oocyte to preserve a condition of ‘normality’.
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20
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Neupane J, Vandewoestyne M, Heindryckx B, Ghimire S, Lu Y, Qian C, Lierman S, Van Coster R, Gerris J, Deroo T, Deforce D, De Sutter P. A systematic analysis of the suitability of preimplantation genetic diagnosis for mitochondrial diseases in a heteroplasmic mitochondrial mouse model. Hum Reprod 2014; 29:852-9. [DOI: 10.1093/humrep/deu016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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21
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Transmitochondrial mice as models for primary prevention of diseases caused by mutation in the tRNA(Lys) gene. Proc Natl Acad Sci U S A 2014; 111:3104-9. [PMID: 24510903 DOI: 10.1073/pnas.1318109111] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We generated transmitochondrial mice (mito-mice) that carry a mutation in the tRNA(Lys) gene encoded by mtDNA for use in studies of its pathogenesis and transmission profiles. Because patients with mitochondrial diseases frequently carry mutations in the mitochondrial tRNA(Lys) and tRNA(Leu(UUR)) genes, we focused our efforts on identifying somatic mutations of these genes in mouse lung carcinoma P29 cells. Of the 43 clones of PCR products including the tRNA(Lys) or tRNA(Leu(UUR)) genes in mtDNA of P29 cells, one had a potentially pathogenic mutation (G7731A) in the tRNA(Lys) gene. P29 subclones with predominant amounts of G7731A mtDNA expressed respiration defects, thus suggesting the pathogenicity of this mutation. We then transferred G7731A mtDNA into mouse ES cells and obtained F0 chimeric mice. Mating these F0 mice with C57BL/6J (B6) male mice resulted in the generation of F1 mice with G7731A mtDNA, named "mito-mice-tRNA(Lys7731)." Maternal inheritance and random segregation of G7731A mtDNA occurred in subsequent generations. Mito-mice-tRNA(Lys7731) with high proportions of G7731A mtDNA exclusively expressed respiration defects and disease-related phenotypes and therefore are potential models for mitochondrial diseases due to mutations in the mitochondrial tRNA(Lys) gene. Moreover, the proportion of mutated mtDNA varied markedly among the pups born to each dam, suggesting that selecting oocytes with high proportions of normal mtDNA from affected mothers with tRNA(Lys)-based mitochondrial diseases may be effective as a primary prevention for obtaining unaffected children.
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22
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Wallace DC, Chalkia D. Mitochondrial DNA genetics and the heteroplasmy conundrum in evolution and disease. Cold Spring Harb Perspect Biol 2013; 5:a021220. [PMID: 24186072 PMCID: PMC3809581 DOI: 10.1101/cshperspect.a021220] [Citation(s) in RCA: 415] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The unorthodox genetics of the mtDNA is providing new perspectives on the etiology of the common "complex" diseases. The maternally inherited mtDNA codes for essential energy genes, is present in thousands of copies per cell, and has a very high mutation rate. New mtDNA mutations arise among thousands of other mtDNAs. The mechanisms by which these "heteroplasmic" mtDNA mutations come to predominate in the female germline and somatic tissues is poorly understood, but essential for understanding the clinical variability of a range of diseases. Maternal inheritance and heteroplasmy also pose major challengers for the diagnosis and prevention of mtDNA disease.
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Affiliation(s)
- Douglas C Wallace
- Center for Mitochondrial and Epigenomic Medicine, The Children's Hospital of Philadelphia, Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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23
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St John J. The control of mtDNA replication during differentiation and development. Biochim Biophys Acta Gen Subj 2013; 1840:1345-54. [PMID: 24183916 DOI: 10.1016/j.bbagen.2013.10.036] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 10/22/2013] [Accepted: 10/23/2013] [Indexed: 12/01/2022]
Abstract
BACKGROUND Mitochondrial DNA (mtDNA) is important for energy production as it encodes some of the key genes of electron transfer chain, where the majority of cellular energy is generated through oxidative phosphorylation (OXPHOS). MtDNA replication is mediated by nuclear DNA-encoded proteins or enzymes, which translocate to the mitochondria, and is strictly regulated throughout development. It starts with approximately 200 copies in each primordial germ cell and these copies undergo expansion and restriction events at various stages of development. SCOPE OF REVIEW I describe the patterns of mtDNA replication at key stages of development. I explain that it is essential to regulate mtDNA copy number and to establish the mtDNA set point in order that the mature, specialised cell acquires the appropriate numbers of mtDNA copy to generate sufficient adenosine triphosphate (ATP) through OXPHOS to undertake its specialised function. I discuss how these processes are dependent on the controlled expression of the nuclear-encoded mtDNA-specific replication factors and that this can be modulated by mtDNA haplotypes. I discuss how these events are altered by certain assisted reproductive technologies, some of which have been proposed to prevent the transmission of mutant mtDNA and others to overcome infertility. Furthermore, some of these technologies are predisposed to transmitting two or more populations of mtDNA, which can be extremely harmful. MAJOR CONCLUSIONS The failure to regulate mtDNA replication and mtDNA transmission during development is disadvantageous. GENERAL SIGNIFICANCE Manipulation of oocytes and embryos can lead to significant implications for the maternal-only transmission of mtDNA. This article is part of a Special Issue entitled Frontiers of mitochondrial research.
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Affiliation(s)
- Justin St John
- Mitochondrial Genetics Group, Centre for Genetic Diseases, Monash Institute of Medical Research, Monash University, 27-31 Wright Street, Clayton, Victoria 3168, Australia.
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24
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Smeets HJM. Preventing the transmission of mitochondrial DNA disorders: selecting the good guys or kicking out the bad guys. Reprod Biomed Online 2013; 27:599-610. [PMID: 24135157 DOI: 10.1016/j.rbmo.2013.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 07/26/2013] [Accepted: 08/01/2013] [Indexed: 01/30/2023]
Abstract
Mitochondrial disorders represent the most common group of inborn errors of metabolism. Clinical manifestations can be extremely variable, ranging from single affected tissues to multisystemic syndromes. Maternally inherited mitochondrial DNA (mtDNA) mutations are a frequent cause, affecting about one in 5000 individuals. The expression of mtDNA mutations differs from nuclear gene defects. Mutations are either homoplasmic or heteroplasmic, and in the latter case disease becomes manifest when the mutation load exceeds a tissue-specific threshold. Mutation load can vary between tissues and in time, and often an exact correlation between mutation load and clinical manifestations is lacking. Because of the possible clinical severity, the lack of treatment and the high recurrence risk of affected offspring for female carriers, couples request prevention of transmission of mtDNA mutations. Previously, choices have been limited due to a segregational bottleneck, which makes the mtDNA mutation load in embryos highly variable and the consequences largely unpredictable. However, recently it was shown that preimplantation genetic diagnosis offers a fair chance of unaffected offspring to carriers of heteroplasmic mtDNA mutations. Technically and ethically challenging possibilities, such maternal spindle transfer and pronuclear transfer, are emerging and providing carriers additional prospects of giving birth to a healthy child.
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Affiliation(s)
- Hubert J M Smeets
- Unit Clinical Genomics, Department of Genetics and Cell Biology, School for Growth and Development and for Cardiovascular Research, Maastricht University Medical Centre, Maastricht, The Netherlands.
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25
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Monnot S, Samuels DC, Hesters L, Frydman N, Gigarel N, Burlet P, Kerbrat V, Lamazou F, Frydman R, Benachi A, Feingold J, Rotig A, Munnich A, Bonnefont JP, Steffann J. Mutation dependance of the mitochondrial DNA copy number in the first stages of human embryogenesis. Hum Mol Genet 2013; 22:1867-72. [DOI: 10.1093/hmg/ddt040] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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26
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Mitochondrial DNA variations in ova and blastocyst: implications in assisted reproduction. Mitochondrion 2013; 13:96-105. [PMID: 23333796 DOI: 10.1016/j.mito.2013.01.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 12/30/2012] [Accepted: 01/07/2013] [Indexed: 11/20/2022]
Abstract
Mitochondrial DNA (mtDNA) of oocyte is critical for its function, embryo quality and development. Analysis of complete mtDNA of 49 oocytes and 18 blastocysts from 67 females opting for IVF revealed 437 nucleotide variations. 40.29% samples had either disease associated or non-synonymous novel or pathogenic mutation in evolutionarily conserved regions. Samples with disease associated mtDNA mutations had low fertilization rate and poor embryo quality, however no difference in implantation or clinical pregnancy rate was observed. Screening mtDNA from oocyte/blastocyst is a simple, clinically reliable method for diagnostic evaluation of female infertility and may reduce risk of mtDNA disease transmission.
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Poor correlation between polar bodies and blastomere mutation load in a patient with m.3243A>G tRNALeu(UUR) point mutation. Mitochondrion 2012; 12:477-9. [DOI: 10.1016/j.mito.2012.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 04/03/2012] [Accepted: 04/26/2012] [Indexed: 01/28/2023]
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28
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Transmission, inheritance and replication of mitochondrial DNA in mammals: implications for reproductive processes and infertility. Cell Tissue Res 2012; 349:795-808. [DOI: 10.1007/s00441-012-1444-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 04/26/2012] [Indexed: 01/03/2023]
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