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Holuka C, Grova N, Charalambous EG, Le Cléac H J, Turner JD, Mposhi A. Transgenerational impacts of early life adversity: from health determinants, implications to epigenetic consequences. Neurosci Biobehav Rev 2024; 164:105785. [PMID: 38945418 DOI: 10.1016/j.neubiorev.2024.105785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/09/2024] [Accepted: 06/23/2024] [Indexed: 07/02/2024]
Abstract
Exposure to different environmental factors, social and socioeconomic factors promotes development of the early-life adversity (ELA) phenotype. The persistence of this phenotype across generations is an interesting phenomenon that remains unexplored. Of late many studies have focused on disease-associated outcomes of ELA following exposure during childhood but the persistence of epigenetic imprints transmitted by ELA exposed parents to their offspring remains poorly described. It is possible that both parents are able to transmit ELA-associated genetic imprints to their offspring via transgenerational inheritance mechanisms. Here, we highlight the role of the mother and father in the biological process of conception, from epigenetic reprogramming cycles to later environmental exposures. We explain some of the known determinants of ELA (pollution, socioeconomic challenges, infections, etc.) and their disease-associated outcomes. Finally, we highlight the role of epigenetics, mitochondria and ncRNAs as mechanisms mediating transgenerational inheritance. Whether these transgenerational inheritance mechanisms occur in the human context remains unclear but there is a large body of suggestive evidence in non-human models that points out to its existence.
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Affiliation(s)
- Cyrielle Holuka
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Luxembourg; Faculty of Science, University of Luxembourg, Belval L-4365, Luxembourg
| | - Nathalie Grova
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Luxembourg; UMR Inserm 1256 nGERE, Nutrition-Génétique et exposition aux risques environnementaux, Institute of Medical Research (Pôle BMS) - University of Lorraine, B.P. 184, Nancy 54511, France
| | - Eleftheria G Charalambous
- Department of Psychiatry and Psychotherapy, University Medecine Greifswald, Ellernholzstr. 1-2, Greifswald 17489, Germany; Department of Psychology, University of Cyprus, Nicosia 2109, Cyprus
| | - Jeanne Le Cléac H
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Luxembourg; Faculty of Science, University of Luxembourg, Belval L-4365, Luxembourg
| | - Jonathan D Turner
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Luxembourg.
| | - Archibold Mposhi
- Immune Endocrine Epigenetics Research Group, Department of Infection and Immunity, Luxembourg Institute of Health, Luxembourg
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2
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Ferreira T, Rodriguez S. Mitochondrial DNA: Inherent Complexities Relevant to Genetic Analyses. Genes (Basel) 2024; 15:617. [PMID: 38790246 PMCID: PMC11121663 DOI: 10.3390/genes15050617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Mitochondrial DNA (mtDNA) exhibits distinct characteristics distinguishing it from the nuclear genome, necessitating specific analytical methods in genetic studies. This comprehensive review explores the complex role of mtDNA in a variety of genetic studies, including genome-wide, epigenome-wide, and phenome-wide association studies, with a focus on its implications for human traits and diseases. Here, we discuss the structure and gene-encoding properties of mtDNA, along with the influence of environmental factors and epigenetic modifications on its function and variability. Particularly significant are the challenges posed by mtDNA's high mutation rate, heteroplasmy, and copy number variations, and their impact on disease susceptibility and population genetic analyses. The review also highlights recent advances in methodological approaches that enhance our understanding of mtDNA associations, advocating for refined genetic research techniques that accommodate its complexities. By providing a comprehensive overview of the intricacies of mtDNA, this paper underscores the need for an integrated approach to genetic studies that considers the unique properties of mitochondrial genetics. Our findings aim to inform future research and encourage the development of innovative methodologies to better interpret the broad implications of mtDNA in human health and disease.
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Affiliation(s)
- Tomas Ferreira
- Bristol Medical School, University of Bristol, Bristol BS8 1UD, UK
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge CB2 0SL, UK
| | - Santiago Rodriguez
- Bristol Medical School, University of Bristol, Bristol BS8 1UD, UK
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
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3
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de Lima CB, Martin H, Pecora Milazzotto M, Sirard MA. Genome-wide methylation profile of mitochondrial DNA across bovine preimplantation development. Epigenetics 2023; 18:2241010. [PMID: 37523633 PMCID: PMC10392754 DOI: 10.1080/15592294.2023.2241010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/29/2023] [Accepted: 07/11/2023] [Indexed: 08/02/2023] Open
Abstract
This study characterized variations in the methylation profile of mitochondrial DNA (mtDNA) during initial bovine embryo development and correlated the presence of methylation with mtDNA transcription. Bovine oocytes were obtained from abattoir ovaries and submitted to in vitro culture procedures. Oocytes and embryos were collected at various stages (immature oocyte, IM; mature oocyte, MII; zygote, ZY; 4-cells, 4C; 16-cells, 16C and blastocysts, BL). Total DNA (including mtDNA) was used for Whole Genome Enzymatic Methyl Sequencing and for quantification of mtDNA copy number. Extracted RNA was used for quantification of mitochondrial transcripts using Droplet Digital PCR. We selected ND6, CYTB, tRNA-Phe and tRNA-Gln based on their location in the mitochondrial genome, functionality and/or previous literature associating these regions with cytosine methylation. The number of mtDNA copies per oocyte/embryo was found to be similar, while methylation levels in mtDNA varied among stages. Higher total methylation levels were found mainly at 4C and 16C. In specific gene regions, higher methylation levels were also observed at 4C and 16C (ND6, CYTB and tRNA-Phe), as well as an inverse correlation with the quantity of transcripts for these regions. This is a first description of epigenetic changes occurring in mtDNA during early embryonic development. Our results indicate that methylation might regulate the mtDNA transcription at a local level, particularly around the time of embryonic genome activation.
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Affiliation(s)
- Camila Bruna de Lima
- Centre de Recherche En Reproduction, Développement Et Santé Intergénérationnelle (CRDSI), Département des Sciences Animales, Université Laval, Québec, QC, Canada
- Universidade Federal Do ABC, Centro de Ciências Naturais E Humanas, Santo André, SP, Brazil
| | - Hélène Martin
- Centre de Recherche En Reproduction, Développement Et Santé Intergénérationnelle (CRDSI), Département des Sciences Animales, Université Laval, Québec, QC, Canada
| | - Marcella Pecora Milazzotto
- Centre de Recherche En Reproduction, Développement Et Santé Intergénérationnelle (CRDSI), Département des Sciences Animales, Université Laval, Québec, QC, Canada
- Universidade Federal Do ABC, Centro de Ciências Naturais E Humanas, Santo André, SP, Brazil
| | - Marc-André Sirard
- Centre de Recherche En Reproduction, Développement Et Santé Intergénérationnelle (CRDSI), Département des Sciences Animales, Université Laval, Québec, QC, Canada
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4
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Sgueglia G, Longobardi S, Valerio D, Campitiello MR, Colacurci N, Di Pietro C, Battaglia R, D'Hooghe T, Altucci L, Dell'Aversana C. The impact of epigenetic landscape on ovarian cells in infertile older women undergoing IVF procedures. Clin Epigenetics 2023; 15:76. [PMID: 37143127 PMCID: PMC10161563 DOI: 10.1186/s13148-023-01490-0] [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: 02/28/2023] [Accepted: 04/24/2023] [Indexed: 05/06/2023] Open
Abstract
The constant decline in fertility and older reproductive age is the major cause of low clinical pregnancy rates in industrialised countries. Epigenetic mechanisms impact on proper embryonic development in women undergoing in vitro fertilisation (IVF) protocols. Here, we describe the main epigenetic modifications that may influence female reproduction and could affect IVF success.
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Affiliation(s)
- Giulia Sgueglia
- Department of Precision Medicine, University of Campania 'Luigi Vanvitelli', Programma di Epigenetica Medica, Azienda Ospedaliera Universitaria, Naples, Italy
| | | | - Domenico Valerio
- Outpatient Fertility Unit, University of Campania 'Luigi Vanvitelli', 80138, Naples, Italy
| | - Maria Rosaria Campitiello
- Department of Obstetrics and Gynecology and Physiopathology of Human Reproduction, ASL Salerno, Salerno, Italy
| | - Nicola Colacurci
- Outpatient Fertility Unit, University of Campania 'Luigi Vanvitelli', 80138, Naples, Italy
- Department of Woman, Child and General and Special Surgery, University of Campania 'Luigi Vanvitelli', 80138, Naples, Italy
| | - Cinzia Di Pietro
- Department of Biomedical and Biotechnological Sciences, Section of Biology and Genetics "Giovanni Sichel", University of Catania, 95123, Catania, CT, Italy
| | - Rosalia Battaglia
- Department of Biomedical and Biotechnological Sciences, Section of Biology and Genetics "Giovanni Sichel", University of Catania, 95123, Catania, CT, Italy
| | | | - Lucia Altucci
- Department of Precision Medicine, University of Campania 'Luigi Vanvitelli', Programma di Epigenetica Medica, Azienda Ospedaliera Universitaria, Naples, Italy.
- BIOGEM, Ariano Irpino, Italy.
- Institute of Experimental Endocrinology and Oncology 'Gaetano Salvatore' (IEOS)-National Research Council (CNR), Naples, Italy.
| | - Carmela Dell'Aversana
- Department of Precision Medicine, University of Campania 'Luigi Vanvitelli', Programma di Epigenetica Medica, Azienda Ospedaliera Universitaria, Naples, Italy.
- Institute of Experimental Endocrinology and Oncology 'Gaetano Salvatore' (IEOS)-National Research Council (CNR), Naples, Italy.
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Iqbal W, Zhou W. Computational Methods for Single-cell DNA Methylome Analysis. GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:48-66. [PMID: 35718270 PMCID: PMC10372927 DOI: 10.1016/j.gpb.2022.05.007] [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: 12/31/2021] [Revised: 04/28/2022] [Accepted: 05/10/2022] [Indexed: 11/19/2022]
Abstract
Dissecting intercellular epigenetic differences is key to understanding tissue heterogeneity. Recent advances in single-cell DNA methylome profiling have presented opportunities to resolve this heterogeneity at the maximum resolution. While these advances enable us to explore frontiers of chromatin biology and better understand cell lineage relationships, they pose new challenges in data processing and interpretation. This review surveys the current state of computational tools developed for single-cell DNA methylome data analysis. We discuss critical components of single-cell DNA methylome data analysis, including data preprocessing, quality control, imputation, dimensionality reduction, cell clustering, supervised cell annotation, cell lineage reconstruction, gene activity scoring, and integration with transcriptome data. We also highlight unique aspects of single-cell DNA methylome data analysis and discuss how techniques common to other single-cell omics data analyses can be adapted to analyze DNA methylomes. Finally, we discuss existing challenges and opportunities for future development.
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Affiliation(s)
- Waleed Iqbal
- Center for Computational and Genomic Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Wanding Zhou
- Center for Computational and Genomic Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Milazzotto MP, Ispada J, de Lima CB. Metabolism-epigenetic interactions on in vitro produced embryos. Reprod Fertil Dev 2022; 35:84-97. [PMID: 36592974 DOI: 10.1071/rd22203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Metabolism and epigenetics, which reciprocally regulate each other in different cell types, are fundamental aspects of cellular adaptation to the environment. Evidence in cancer and stem cells has shown that the metabolic status modifies the epigenome while epigenetic mechanisms regulate the expression of genes involved in metabolic processes, thereby altering the metabolome. This crosstalk occurs as many metabolites serve as substrates or cofactors of chromatin-modifying enzymes. If we consider the intense metabolic dynamic and the epigenetic remodelling of the embryo, the comprehension of these regulatory networks will be important not only for understanding early embryonic development, but also to determine in vitro culture conditions that support embryo development and may insert positive regulatory marks that may persist until adult life. In this review, we focus on how metabolism may affect epigenetic reprogramming of the early stages of development, in particular acetylation and methylation of histone and DNA. We also present other metabolic modifications in bovine embryos, such as lactylation, highlighting the promising epigenetic and metabolic targets to improve conditions for in vitro embryo development.
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Affiliation(s)
- Marcella Pecora Milazzotto
- Laboratory of Embryo Metabolism and Epigenomic, Center of Natural and Human Science, Federal University of ABC, Santo Andre, SP, Brazil
| | - Jessica Ispada
- Laboratory of Embryo Metabolism and Epigenomic, Center of Natural and Human Science, Federal University of ABC, Santo Andre, SP, Brazil
| | - Camila Bruna de Lima
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle (CRDSI), Département des Sciences Animales, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Quebec City, QC, Canada
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7
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Mitochondrial genome undergoes de novo DNA methylation that protects mtDNA against oxidative damage during the peri-implantation window. Proc Natl Acad Sci U S A 2022; 119:e2201168119. [PMID: 35858425 PMCID: PMC9335330 DOI: 10.1073/pnas.2201168119] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mitochondrial remodeling during the peri-implantation stage is the hallmark event essential for normal embryogenesis. Among the changes, enhanced oxidative phosphorylation is critical for supporting high energy demands of postimplantation embryos, but increases mitochondrial oxidative stress, which in turn threatens mitochondrial DNA (mtDNA) stability. However, how mitochondria protect their own histone-lacking mtDNA, during this stage remains unclear. Concurrently, the mitochondrial genome gain DNA methylation by this stage. Its spatiotemporal coincidence with enhanced mitochondrial stress led us to ask if mtDNA methylation has a role in maintaining mitochondrial genome stability. Herein, we report that mitochondrial genome undergoes de novo mtDNA methylation that can protect mtDNA against enhanced oxidative damage during the peri-implantation window. Mitochondrial genome gains extensive mtDNA methylation during transition from blastocysts to postimplantation embryos, thus establishing relatively hypermethylated mtDNA from hypomethylated state in blastocysts. Mechanistic study revealed that DNA methyltransferase 3A (DNMT3A) and DNMT3B enter mitochondria during this process and bind to mtDNA, via their unique mitochondrial targeting sequences. Importantly, loss- and gain-of-function analyses indicated that DNMT3A and DNMT3B are responsible for catalyzing de novo mtDNA methylation, in a synergistic manner. Finally, we proved, in vivo and in vitro, that increased mtDNA methylation functions to protect mitochondrial genome against mtDNA damage induced by increased mitochondrial oxidative stress. Together, we reveal mtDNA methylation dynamics and its underlying mechanism during the critical developmental window. We also provide the functional link between mitochondrial epigenetic remodeling and metabolic changes, which reveals a role for nuclear-mitochondrial crosstalk in establishing mitoepigenetics and maintaining mitochondrial homeostasis.
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Bordoni L, Malinowska AM, Petracci I, Szwengiel A, Gabbianelli R, Chmurzynska A. Diet, Trimethylamine Metabolism, and Mitochondrial DNA: An Observational Study. Mol Nutr Food Res 2022; 66:e2200003. [PMID: 35490412 DOI: 10.1002/mnfr.202200003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 04/14/2022] [Indexed: 12/11/2022]
Abstract
SCOPE Mitochondrial DNA copy number (mtDNAcn) and its methylation level in the D-loop area have been correlated with metabolic health and are suggested to vary in response to environmental stimuli, including diet. Circulating levels of trimethylamine-n-oxide (TMAO), which is an oxidative derivative of the trimethylamine (TMA) produced by the gut microbiome from dietary precursors, have been associated with chronic diseases and are suggested to have an impact on mitochondrial dynamics. This study is aimed to investigate the relationship between diet, TMA, TMAO, and mtDNAcn, as well as DNA methylation. METHODS AND RESULTS Two hundred subjects with extreme (healthy and unhealthy) dietary patterns are recruited. Dietary records are collected to assess their nutrient intake and diets' quality (Healthy Eating Index). Blood levels of TMA and TMAO, circulating levels of TMA precursors and their dietary intakes are measured. MtDNAcn, nuclear DNA methylation long interspersed nuclear element 1 (LINE-1), and strand-specific D-loop methylation levels are assessed. There is no association between dietary patterns and mtDNAcn. The TMAO/TMA ratio is negatively correlated with d-loop methylation levels but positively with mtDNAcn. CONCLUSIONS These findings suggest a potential association between TMA metabolism and mitochondrial dynamics (and mtDNA), indicating a new avenue for further research.
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Affiliation(s)
- Laura Bordoni
- Unit of Molecular Biology and Nutrigenomics, School of Pharmacy, University of Camerino, Camerino, 62032, MC, Italy
| | - Anna M Malinowska
- Department of Human Nutrition and Dietetics, Poznań University of Life Sciences, Poznań, 60-624, Poland
| | - Irene Petracci
- School of Advanced Studies, University of Camerino, Camerino, 62032, MC, Italy
| | - Artur Szwengiel
- Department of Food Technology of Plant Origin, Poznań University of Life Sciences, Poznań, 60-624, Poland
| | - Rosita Gabbianelli
- Unit of Molecular Biology and Nutrigenomics, School of Pharmacy, University of Camerino, Camerino, 62032, MC, Italy
| | - Agata Chmurzynska
- Department of Human Nutrition and Dietetics, Poznań University of Life Sciences, Poznań, 60-624, Poland
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9
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Wang C, Zhang Y. Endoplasmic Reticulum Stress: A New Research Direction for Polycystic Ovary Syndrome? DNA Cell Biol 2022; 41:356-367. [PMID: 35353637 DOI: 10.1089/dna.2021.1050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Polycystic ovary syndrome (PCOS) is one of the most common gynecological endocrine disorders, with sporadic ovulation, excessive androgens, and polycystic ovarian changes as the main clinical manifestations. Due to the high heterogeneity of its clinical manifestations, the discussion on its pathogenesis has not been unified. Current research has found that genetic factors, hyperandrogenism, chronic inflammation and oxidative stress, insulin resistance, and obesity are strongly associated with PCOS. Recently, when studying the specific mechanisms of the abovementioned factors in PCOS, the biological response process of endoplasmic reticulum stress (ERS) has gradually come to researchers' attention, and several studies have confirmed the involvement of ERS in the pathogenesis of PCOS and the improvement of a series of pathological manifestations of PCOS after the application of ERS inhibitors, which may be a new entry point for the treatment of PCOS. In this article, we review the relationship between ERS and various pathogenic factors of PCOS.
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Affiliation(s)
- Chengzhe Wang
- Department of Gynecology of traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan City, China
| | - Yingjie Zhang
- Department of Gynecology of traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan City, China
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10
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Okada T, Sun X, McIlfatrick S, St. John JC. Low guanine content and biased nucleotide distribution in vertebrate mtDNA can cause overestimation of non-CpG methylation. NAR Genom Bioinform 2022; 4:lqab119. [PMID: 35047811 PMCID: PMC8759572 DOI: 10.1093/nargab/lqab119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/24/2021] [Accepted: 01/09/2022] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial DNA (mtDNA) methylation in vertebrates has been hotly debated for over 40 years. Most contrasting results have been reported following bisulfite sequencing (BS-seq) analyses. We addressed whether BS-seq experimental and analysis conditions influenced the estimation of the levels of methylation in specific mtDNA sequences. We found false positive non-CpG methylation in the CHH context (fpCHH) using unmethylated Sus scrofa mtDNA BS-seq data. fpCHH methylation was detected on the top/plus strand of mtDNA within low guanine content regions. These top/plus strand sequences of fpCHH regions would become extremely AT-rich sequences after BS-conversion, whilst bottom/minus strand sequences remained almost unchanged. These unique sequences caused BS-seq aligners to falsely assign the origin of each strand in fpCHH regions, resulting in false methylation calls. fpCHH methylation detection was enhanced by short sequence reads, short library inserts, skewed top/bottom read ratios and non-directional read mapping modes. We confirmed no detectable CHH methylation in fpCHH regions by BS-amplicon sequencing. The fpCHH peaks were located in the D-loop, ATP6, ND2, ND4L, ND5 and ND6 regions and identified in our S. scrofa ovary and oocyte data and human BS-seq data sets. We conclude that non-CpG methylation could potentially be overestimated in specific sequence regions by BS-seq analysis.
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11
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Affiliation(s)
- Ying Zhang
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Faculté des Sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Pavillon INAF, Université Laval, Québec, Québec, Canada
| | - Marc-André Sirard
- Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Faculté des Sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Pavillon INAF, Université Laval, Québec, Québec, Canada
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12
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Bicci I, Calabrese C, Golder ZJ, Gomez-Duran A, Chinnery PF. Single-molecule mitochondrial DNA sequencing shows no evidence of CpG methylation in human cells and tissues. Nucleic Acids Res 2021; 49:12757-12768. [PMID: 34850165 PMCID: PMC8682748 DOI: 10.1093/nar/gkab1179] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/29/2021] [Accepted: 11/18/2021] [Indexed: 01/11/2023] Open
Abstract
Methylation on CpG residues is one of the most important epigenetic modifications of nuclear DNA, regulating gene expression. Methylation of mitochondrial DNA (mtDNA) has been studied using whole genome bisulfite sequencing (WGBS), but recent evidence has uncovered technical issues which introduce a potential bias during methylation quantification. Here, we validate the technical concerns of WGBS, and develop and assess the accuracy of a new protocol for mtDNA nucleotide variant-specific methylation using single-molecule Oxford Nanopore Sequencing (ONS). Our approach circumvents confounders by enriching for full-length molecules over nuclear DNA. Variant calling analysis against showed that 99.5% of homoplasmic mtDNA variants can be reliably identified providing there is adequate sequencing depth. We show that some of the mtDNA methylation signal detected by ONS is due to sequence-specific false positives introduced by the technique. The residual signal was observed across several human primary and cancer cell lines and multiple human tissues, but was always below the error threshold modelled using negative controls. We conclude that there is no evidence for CpG methylation in human mtDNA, thus resolving previous controversies. Additionally, we developed a reliable protocol to study epigenetic modifications of mtDNA at single-molecule and single-base resolution, with potential applications beyond CpG methylation.
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Affiliation(s)
- Iacopo Bicci
- MRC-Mitochondrial Biology Unit, The Keith Peters Building, Cambridge CB2 0XY, UK.,Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Claudia Calabrese
- MRC-Mitochondrial Biology Unit, The Keith Peters Building, Cambridge CB2 0XY, UK.,Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Zoe J Golder
- MRC-Mitochondrial Biology Unit, The Keith Peters Building, Cambridge CB2 0XY, UK.,Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Aurora Gomez-Duran
- MRC-Mitochondrial Biology Unit, The Keith Peters Building, Cambridge CB2 0XY, UK.,Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK.,Centro de Investigaciones Biológicas Margarita Salas. Spanish National Research Council, Madrid, Spain
| | - Patrick F Chinnery
- MRC-Mitochondrial Biology Unit, The Keith Peters Building, Cambridge CB2 0XY, UK.,Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
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13
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Sirard MA. How the environment affects early embryonic development. Reprod Fertil Dev 2021; 34:203-213. [PMID: 35231267 DOI: 10.1071/rd21266] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In the field of animal reproduction, the environment associated with gametes and embryos refers to the parents' condition as well as conditions surrounding gametes and embryos in vivo or in vitro . This environment is now known to influence not only the functionality of the early embryo but potentially the future phenotype of the offspring. Using transcriptomic and epigenetic molecular analysis, and the bovine model, recent research has shown that both the female and the male metabolic status, for example age, can affect gene expression and gene programming in the embryo. Evidence demonstrates that milking cows, which are losing weight at the time of conception, generates compromised embryos and offspring with a unique metabolic signature. A similar phenomenon has been associated with different culture conditions and the IVF procedure. The general common consequence of these situations is an embryo behaving on 'economy' mode where translation, cell division and ATP production is reduced, potentially to adapt to the perceived future environment. Few epidemiological studies have been done in bovines to assess if these changes result in a different phenotype and more studies are required to associate specific molecular changes in embryos with visible consequences later in life.
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Affiliation(s)
- Marc-André Sirard
- Faculté des Sciences de l'Agriculture et de l'Alimentation, Département des Sciences Animales, Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle (CRDSI), Université Laval, Québec, QC G1V 0A6, Canada
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14
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Chiaratti MR. Uncovering the important role of mitochondrial dynamics in oogenesis: impact on fertility and metabolic disorder transmission. Biophys Rev 2021; 13:967-981. [PMID: 35059021 PMCID: PMC8724343 DOI: 10.1007/s12551-021-00891-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 11/01/2021] [Indexed: 12/12/2022] Open
Abstract
Oocyte health is tightly tied to mitochondria given their role in energy production, metabolite supply, calcium (Ca2+) buffering, and cell death regulation, among others. In turn, mitochondrial function strongly relies on these organelle dynamics once cyclic events of fusion and fission (division) are required for mitochondrial turnover, positioning, content homogenization, metabolic flexibility, interaction with subcellular compartments, etc. Importantly, during oogenesis, mitochondria change their architecture from an "orthodox" elongated shape characterized by the presence of numerous transversely oriented cristae to a round-to-oval morphology containing arched and concentrically arranged cristae. This, along with evidence showing that mitochondrial function is kept quiescent during most part of oocyte development, suggests an important role of mitochondrial dynamics in oogenesis. To investigate this, recent works have downregulated/upregulated in oocytes the expression of key effectors of mitochondrial dynamics, including mitofusins 1 (MFN1) and 2 (MFN2) and the dynamin-related protein 1 (DRP1). As a result, both MFN1 and DRP1 were found to be essential to oogenesis and fertility, while MFN2 deletion led to offspring with increased weight gain and glucose intolerance. Curiously, neither MFN1/MFN2 deficiency nor DRP1 overexpression enhanced mitochondrial fragmentation, indicating that mitochondrial size is strictly regulated in oocytes. Therefore, the present work seeks to discuss the role of mitochondria in supporting oogenesis as well as recent findings connecting defective mitochondrial dynamics in oocytes with infertility and transmission of metabolic disorders.
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Affiliation(s)
- Marcos Roberto Chiaratti
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, 13565-905 Brazil
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15
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Zhao H, Ma D, Xie J, Sanchez O, Huang F, Yuan C. Live-Cell Probe for In Situ Single-Cell Monitoring of Mitochondrial DNA Methylation. ACS Sens 2021; 6:3575-3586. [PMID: 34586782 DOI: 10.1021/acssensors.1c00731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Mitochondria, as the center of energy production, play an important role in cell homeostasis by regulating the cellular metabolism and mediating the cellular response to stress. Epigenetic changes such as DNA and histone methylation have been increasingly recognized to play a significant role in homeostasis and stress response. The cross-talking between the metabolome and the epigenome has attracted significant attention in recent years but with a major focus on how metabolism contributes to epigenomic changes. Few studies have focused on how epigenetic modifications may alter the mitochondrial composition and activity. In this work, we designed a novel probe targeting methylated CpGs of mitochondrial DNA (mtDNA). We demonstrated the capability of our probe to reveal the spatial distribution of methylated mtDNA and capture the mtDNA methylation changes at a single-cell level. We were also able to track single-cell mtDNA and nDNA methylation simultaneously and discovered the unsynchronized dynamics of the nucleus and mitochondria. Our tool offers a unique opportunity to understand the epigenetic regulation of mtDNA and its dynamic response to the microenvironment and cellular changes.
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Affiliation(s)
- Han Zhao
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Donghan Ma
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Junkai Xie
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Oscar Sanchez
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Fang Huang
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue University Center for Cancer Research, West Lafayette, Indiana 47907, United States
| | - Chongli Yuan
- Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Purdue University Center for Cancer Research, West Lafayette, Indiana 47907, United States
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16
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Zhou Q, Guan P, Zhu Z, Cheng S, Zhou C, Wang H, Xu Q, Sung WK, Li G. ASMdb: a comprehensive database for allele-specific DNA methylation in diverse organisms. Nucleic Acids Res 2021; 50:D60-D71. [PMID: 34664666 PMCID: PMC8728259 DOI: 10.1093/nar/gkab937] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 09/27/2021] [Accepted: 09/30/2021] [Indexed: 11/18/2022] Open
Abstract
DNA methylation is known to be the most stable epigenetic modification and has been extensively studied in relation to cell differentiation, development, X chromosome inactivation and disease. Allele-specific DNA methylation (ASM) is a well-established mechanism for genomic imprinting and regulates imprinted gene expression. Previous studies have confirmed that certain special regions with ASM are susceptible and closely related to human carcinogenesis and plant development. In addition, recent studies have proven ASM to be an effective tumour marker. However, research on the functions of ASM in diseases and development is still extremely scarce. Here, we collected 4400 BS-Seq datasets and 1598 corresponding RNA-Seq datasets from 47 species, including human and mouse, to establish a comprehensive ASM database. We obtained the data on DNA methylation level, ASM and allele-specific expressed genes (ASEGs) and further analysed the ASM/ASEG distribution patterns of these species. In-depth ASM distribution analysis and differential methylation analysis conducted in nine cancer types showed results consistent with the reported changes in ASM in key tumour genes and revealed several potential ASM tumour-related genes. Finally, integrating these results, we constructed the first well-resourced and comprehensive ASM database for 47 species (ASMdb, www.dna-asmdb.com).
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Affiliation(s)
- Qiangwei Zhou
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Pengpeng Guan
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhixian Zhu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Sheng Cheng
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Cong Zhou
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Huanhuan Wang
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Qian Xu
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
| | - Wing-Kin Sung
- Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China.,Department of Computer Science, National University of Singapore, Singapore 117417, Singapore.,Department of Computational and Systems Biology, Genome Institute of Singapore, Singapore 138672, Singapore
| | - Guoliang Li
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China.,Agricultural Bioinformatics Key Laboratory of Hubei Province, Hubei Engineering Technology Research Center of Agricultural Big Data, 3D Genomics Research Center, College of Informatics, Huazhong Agricultural University, Wuhan 430070, China
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17
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Lüth T, Wasner K, Klein C, Schaake S, Tse R, Pereira SL, Laß J, Sinkkonen L, Grünewald A, Trinh J. Nanopore Single-Molecule Sequencing for Mitochondrial DNA Methylation Analysis: Investigating Parkin-Associated Parkinsonism as a Proof of Concept. Front Aging Neurosci 2021; 13:713084. [PMID: 34650424 PMCID: PMC8506010 DOI: 10.3389/fnagi.2021.713084] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 09/01/2021] [Indexed: 01/08/2023] Open
Abstract
Objective: To establish a workflow for mitochondrial DNA (mtDNA) CpG methylation using Nanopore whole-genome sequencing and perform first pilot experiments on affected Parkin biallelic mutation carriers (Parkin-PD) and healthy controls. Background: Mitochondria, including mtDNA, are established key players in Parkinson's disease (PD) pathogenesis. Mutations in Parkin, essential for degradation of damaged mitochondria, cause early-onset PD. However, mtDNA methylation and its implication in PD is understudied. Herein, we establish a workflow using Nanopore sequencing to directly detect mtDNA CpG methylation and compare mtDNA methylation between Parkin-related PD and healthy individuals. Methods: To obtain mtDNA, whole-genome Nanopore sequencing was performed on blood-derived from five Parkin-PD and three control subjects. In addition, induced pluripotent stem cell (iPSC)-derived midbrain neurons from four of these patients with PD and the three control subjects were investigated. The workflow was validated, using methylated and unmethylated 897 bp synthetic DNA samples at different dilution ratios (0, 50, 100% methylation) and mtDNA without methylation. MtDNA CpG methylation frequency (MF) was detected using Nanopolish and Megalodon. Results: Across all blood-derived samples, we obtained a mean coverage of 250.3X (SD ± 80.5X) and across all neuron-derived samples 830X (SD ± 465X) of the mitochondrial genome. We detected overall low-level CpG methylation from the blood-derived DNA (mean MF ± SD = 0.029 ± 0.041) and neuron-derived DNA (mean MF ± SD = 0.019 ± 0.035). Validation of the workflow, using synthetic DNA samples showed that highly methylated DNA molecules were prone to lower Guppy Phred quality scores and thereby more likely to fail Guppy base-calling. CpG methylation in blood- and neuron-derived DNA was significantly lower in Parkin-PD compared to controls (Mann-Whitney U-test p < 0.05). Conclusion: Nanopore sequencing is a useful method to investigate mtDNA methylation architecture, including Guppy-failed reads is of importance when investigating highly methylated sites. We present a mtDNA methylation workflow and suggest methylation variability across different tissues and between Parkin-PD patients and controls as an initial model to investigate.
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Affiliation(s)
- Theresa Lüth
- Institute of Neurogenetics BMF, University of Lübeck and University Hospital Schleswig-Holstein Campus Lübeck, Lübeck, Germany
| | - Kobi Wasner
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Belvaux, Luxembourg
| | - Christine Klein
- Institute of Neurogenetics BMF, University of Lübeck and University Hospital Schleswig-Holstein Campus Lübeck, Lübeck, Germany
| | - Susen Schaake
- Institute of Neurogenetics BMF, University of Lübeck and University Hospital Schleswig-Holstein Campus Lübeck, Lübeck, Germany
| | - Ronnie Tse
- Institute of Neurogenetics BMF, University of Lübeck and University Hospital Schleswig-Holstein Campus Lübeck, Lübeck, Germany
| | - Sandro L. Pereira
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Belvaux, Luxembourg
| | - Joshua Laß
- Institute of Neurogenetics BMF, University of Lübeck and University Hospital Schleswig-Holstein Campus Lübeck, Lübeck, Germany
| | - Lasse Sinkkonen
- Department of Life Sciences and Medicine, University of Luxembourg, Belvaux, Luxembourg
| | - Anne Grünewald
- Institute of Neurogenetics BMF, University of Lübeck and University Hospital Schleswig-Holstein Campus Lübeck, Lübeck, Germany
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Belvaux, Luxembourg
| | - Joanne Trinh
- Institute of Neurogenetics BMF, University of Lübeck and University Hospital Schleswig-Holstein Campus Lübeck, Lübeck, Germany
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18
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St John JC. Epigenetic Regulation of the Nuclear and Mitochondrial Genomes: Involvement in Metabolism, Development, and Disease. Annu Rev Anim Biosci 2021; 9:203-224. [PMID: 33592161 DOI: 10.1146/annurev-animal-080520-083353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Our understanding of the interactions between the nuclear and mitochondrial genomes is becoming increasingly important as they are extensively involved in establishing early development and developmental progression. Evidence from various biological systems indicates the interdependency between the genomes, which requires a high degree of compatibility and synchrony to ensure effective cellular function throughout development and in the resultant offspring. During development, waves of DNA demethylation, de novo methylation, and maintenance methylation act on the nuclear genome and typify oogenesis and pre- and postimplantation development. At the same time, significant changes in mitochondrial DNA copy number influence the metabolic status of the developing organism in a typically cell-type-specific manner. Collectively, at any given stage in development, these actions establish genomic balance that ensures each developmental milestone is met and that the organism's program for life is established.
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Affiliation(s)
- Justin C St John
- Mitochondrial Genetics Group, Robinson Research Institute and School of Medicine, University of Adelaide, Adelaide, South Australia 5005, Australia;
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19
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Chew K, Zhao L. Interactions of Mitochondrial Transcription Factor A with DNA Damage: Mechanistic Insights and Functional Implications. Genes (Basel) 2021; 12:genes12081246. [PMID: 34440420 PMCID: PMC8393399 DOI: 10.3390/genes12081246] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/11/2021] [Accepted: 08/13/2021] [Indexed: 12/17/2022] Open
Abstract
Mitochondria have a plethora of functions in eukaryotic cells, including cell signaling, programmed cell death, protein cofactor synthesis, and various aspects of metabolism. The organelles carry their own genomic DNA, which encodes transfer and ribosomal RNAs and crucial protein subunits in the oxidative phosphorylation system. Mitochondria are vital for cellular and organismal functions, and alterations of mitochondrial DNA (mtDNA) have been linked to mitochondrial disorders and common human diseases. As such, how the cell maintains the integrity of the mitochondrial genome is an important area of study. Interactions of mitochondrial proteins with mtDNA damage are critically important for repairing, regulating, and signaling mtDNA damage. Mitochondrial transcription factor A (TFAM) is a key player in mtDNA transcription, packaging, and maintenance. Due to the extensive contact of TFAM with mtDNA, it is likely to encounter many types of mtDNA damage and secondary structures. This review summarizes recent research on the interaction of human TFAM with different forms of non-canonical DNA structures and discusses the implications on mtDNA repair and packaging.
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20
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Nedoluzhko A, Mjelle R, Renström M, Skjærven KH, Piferrer F, Fernandes JMO. The first mitochondrial 5-methylcytosine map in a non-model teleost (Oreochromis niloticus) reveals extensive strand-specific and non-CpG methylation. Genomics 2021; 113:3050-3057. [PMID: 34245830 DOI: 10.1016/j.ygeno.2021.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 06/16/2021] [Accepted: 07/05/2021] [Indexed: 12/26/2022]
Abstract
DNA methylation is one of the main epigenetic mechanisms that regulate gene expression in a manner that depends on the genomic context and varies considerably across taxa. This DNA modification was first found in nuclear genomes of eukaryote several decades ago and it has also been described in mitochondrial DNA. It has recently been shown that mitochondrial DNA is extensively methylated in mammals and other vertebrates. Our current knowledge of mitochondrial DNA methylation in fish is very limited, especially in non-model teleosts. In this study, using whole-genome bisulfite sequencing, we determined methylation patterns within non-CpG (CH) and CpG (CG) contexts in the mitochondrial genome of Nile tilapia, a non-model teleost of high economic importance. Our results demonstrate the presence of mitochondrial DNA methylation in this species predominantly within a non-CpG context, similarly to mammals. We found a strand-specific distribution of methylation, in which highly methylated cytosines were located on the minus strand. The D-loop region had the highest mean methylation level among all mitochondrial loci. Our data provide new insights into the potential role of epigenetic mechanisms in regulating metabolic flexibility of mitochondria in fish, with implications in various biological processes, such as growth and development.
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Affiliation(s)
- Artem Nedoluzhko
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | - Robin Mjelle
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway; Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Maria Renström
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | | | - Francesc Piferrer
- Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
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21
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Coppedè F. One-carbon epigenetics and redox biology of neurodegeneration. Free Radic Biol Med 2021; 170:19-33. [PMID: 33307166 DOI: 10.1016/j.freeradbiomed.2020.12.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/01/2020] [Accepted: 12/02/2020] [Indexed: 12/12/2022]
Abstract
One-carbon metabolism provides the methyl groups for both DNA and histone tail methylation reactions, two of the main epigenetic processes that tightly regulate the chromatin structure and gene expression levels. Several enzymes involved in one-carbon metabolism, as well as several epigenetic enzymes, are regulated by intracellular metabolites and redox cofactors, but their expression levels are in turn regulated by epigenetic modifications, in such a way that metabolism and gene expression reciprocally regulate each other to maintain homeostasis and regulate cell growth, survival, differentiation and response to environmental stimuli. Increasing evidence highlights the contribution of impaired one-carbon metabolism and epigenetic modifications in neurodegeneration. This article provides an overview of DNA and histone tail methylation changes in major neurodegenerative disorders, namely Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, discussing the contribution of oxidative stress and impaired one-carbon and redox metabolism to their onset and progression.
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Affiliation(s)
- Fabio Coppedè
- Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Via Roma 55, 56126, Pisa, Italy.
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22
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Breton S, Ghiselli F, Milani L. Mitochondrial Short-Term Plastic Responses and Long-Term Evolutionary Dynamics in Animal Species. Genome Biol Evol 2021; 13:6248094. [PMID: 33892508 PMCID: PMC8290114 DOI: 10.1093/gbe/evab084] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 04/13/2021] [Accepted: 04/20/2021] [Indexed: 12/15/2022] Open
Abstract
How do species respond or adapt to environmental changes? The answer to this depends partly on mitochondrial epigenetics and genetics, new players in promoting adaptation to both short- and long-term environmental changes. In this review, we explore how mitochondrial epigenetics and genetics mechanisms, such as mtDNA methylation, mtDNA-derived noncoding RNAs, micropeptides, mtDNA mutations, and adaptations, can contribute to animal plasticity and adaptation. We also briefly discuss the challenges in assessing mtDNA adaptive evolution. In sum, this review covers new advances in the field of mitochondrial genomics, many of which are still controversial, and discusses processes still somewhat obscure, and some of which are still quite speculative and require further robust experimentation.
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Affiliation(s)
- 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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23
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Leroux É, Brosseau C, Angers B, Angers A, Breton S. [Mitochondrial DNA methylation: Controversies, issues and perspectives]. Med Sci (Paris) 2021; 37:258-264. [PMID: 33739273 DOI: 10.1051/medsci/2021011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
DNA methylation is an epigenetic mechanism that has been largely probed regarding eukaryotic nuclear genome and bacteria, and its role is especially crucial in the regulation of gene expression. In mammals, it is almost exclusively acting on a cytosine preceding a guanine (CpG), whereas it presents itself mainly in a non-CpG context in bacteria's DNA. Conversely to nuclear and bacterial genomes, the existence of methylation in the mitochondrial genome is still widely debated. This controversy has been attributed to structural differences between the nuclear and mitochondrial genomes, and to the techniques used to study methylation of cytosines, which were rather optimized for the study of nuclear DNA. However, novel studies suggest that cytosine methylation is truly existing in mitochondria, and that it is mostly found in a non-CpG context, just like in their evolutionary relative, the bacteria.
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Affiliation(s)
- Émélie Leroux
- Département de sciences biologiques, Université de Montréal, Campus MIL, Faculté des Arts et des Sciences, CP 6128, Succursale Centre-Ville, Montréal QC, H3C 3J7, Canada
| | - Cindy Brosseau
- Département de sciences biologiques, Université de Montréal, Campus MIL, Faculté des Arts et des Sciences, CP 6128, Succursale Centre-Ville, Montréal QC, H3C 3J7, Canada
| | - Bernard Angers
- Département de sciences biologiques, Université de Montréal, Campus MIL, Faculté des Arts et des Sciences, CP 6128, Succursale Centre-Ville, Montréal QC, H3C 3J7, Canada
| | - Annie Angers
- Département de sciences biologiques, Université de Montréal, Campus MIL, Faculté des Arts et des Sciences, CP 6128, Succursale Centre-Ville, Montréal QC, H3C 3J7, Canada
| | - Sophie Breton
- Département de sciences biologiques, Université de Montréal, Campus MIL, Faculté des Arts et des Sciences, CP 6128, Succursale Centre-Ville, Montréal QC, H3C 3J7, Canada
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24
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Andreu-Sánchez S, Chen W, Stiller J, Zhang G. Multiple origins of a frameshift insertion in a mitochondrial gene in birds and turtles. Gigascience 2021; 10:giaa161. [PMID: 33463679 PMCID: PMC7814300 DOI: 10.1093/gigascience/giaa161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 10/05/2020] [Accepted: 12/18/2020] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND During evolutionary history, molecular mechanisms have emerged to cope with deleterious mutations. Frameshift insertions in protein-coding sequences are extremely rare because they disrupt the reading frame. There are a few known examples of their correction through translational frameshifting, a process that enables ribosomes to skip nucleotides during translation to regain proper reading frame. Corrective frameshifting has been proposed to act on the single base pair insertion at position 174 of the mitochondrial NADH dehydrogenase subunit 3 gene (ND3) that has been observed in several turtles and birds. However, the relatively sparse taxonomic representation has hampered our understanding of the evolution of this insertion in vertebrates. RESULTS Here, we analyzed 87,707 ND3 sequences from 10,309 vertebrate taxa to reveal the evolutionary history of this insertion and its common genomic characteristics. We confirmed that the insertion only appears in turtles and birds and reconstructed that it evolved independently in both groups with complex patterns of gains and losses. The insertion was observed in almost all bird orders but was absent in all members of the diverse Passeriformes. We found strong conservation in the nucleotides surrounding the insertion in both turtles and birds, which implies that the insertion enforces structural constraints that could be involved in its correction. CONCLUSIONS Our study demonstrates that frameshifts can be widespread and can be retained for millions of years if they are embedded in a conserved sequence theme.
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Affiliation(s)
- Sergio Andreu-Sánchez
- Villum Centre for Biodiversity Genomics, Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
- Present Address: University of Groningen, University Medical Center Groningen, Department of Pediatrics, 9700 RB Groningen, Netherlands
| | - Wanjun Chen
- China National Genebank, BGI-Shenzhen, Beishan Industrial Zone, 518083 Shenzhen, China
| | - Josefin Stiller
- Villum Centre for Biodiversity Genomics, Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Guojie Zhang
- Villum Centre for Biodiversity Genomics, Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
- China National Genebank, BGI-Shenzhen, Beishan Industrial Zone, 518083 Shenzhen, China
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, 650223 Kunming, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, 32 Jiaochang Donglu, 650223 Kunming, China
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25
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Colella M, Cuomo D, Peluso T, Falanga I, Mallardo M, De Felice M, Ambrosino C. Ovarian Aging: Role of Pituitary-Ovarian Axis Hormones and ncRNAs in Regulating Ovarian Mitochondrial Activity. Front Endocrinol (Lausanne) 2021; 12:791071. [PMID: 34975760 PMCID: PMC8716494 DOI: 10.3389/fendo.2021.791071] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/29/2021] [Indexed: 12/17/2022] Open
Abstract
The number of mitochondria in the oocyte along with their functions (e.g., energy production, scavenger activity) decline with age progression. Such multifaceted functions support several processes during oocyte maturation, ranging from energy supply to synthesis of the steroid hormones. Hence, it is hardly surprising that their impairment has been reported in both physiological and premature ovarian aging, wherein they are crucial players in the apoptotic processes that arise in aged ovaries. In any form, ovarian aging implies the progressive damage of the mitochondrial structure and activities as regards to ovarian germ and somatic cells. The imbalance in the circulating hormones and peptides (e.g., gonadotropins, estrogens, AMH, activins, and inhibins), active along the pituitary-ovarian axis, represents the biochemical sign of ovarian aging. Despite the progress accomplished in determining the key role of the mitochondria in preserving ovarian follicular number and health, their modulation by the hormonal signalling pathways involved in ovarian aging has been poorly and randomly explored. Yet characterizing this mechanism is pivotal to molecularly define the implication of mitochondrial dysfunction in physiological and premature ovarian aging, respectively. However, it is fairly difficult considering that the pathways associated with ovarian aging might affect mitochondria directly or by altering the activity, stability and localization of proteins controlling mitochondrial dynamics and functions, either unbalancing other cellular mediators, released by the mitochondria, such as non-coding RNAs (ncRNAs). We will focus on the mitochondrial ncRNAs (i.e., mitomiRs and mtlncRNAs), that retranslocate from the mitochondria to the nucleus, as active players in aging and describe their role in the nuclear-mitochondrial crosstalk and its modulation by the pituitary-ovarian hormone dependent pathways. In this review, we will illustrate mitochondria as targets of the signaling pathways dependent on hormones and peptides active along the pituitary/ovarian axis and as transducers, with a particular focus on the molecules retrieved in the mitochondria, mainly ncRNAs. Given their regulatory function in cellular activities we propose them as potential diagnostic markers and/or therapeutic targets.
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Affiliation(s)
- Marco Colella
- Biogem, Istituto di Biologia e Genetica Molecolare, Ariano Irpino, Italy
- Department of Science and Technology, University of Sannio, Benevento, Italy
- Laboratory of Pre-Clinical and Translational Research, IRCCS, Referral Cancer Center of Basilicata, Rionero in Vulture, Italy
| | - Danila Cuomo
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX, United States
| | - Teresa Peluso
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Ilaria Falanga
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Massimo Mallardo
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples “Federico II”, Naples, Italy
| | - Mario De Felice
- Department of Molecular Medicine and Medical Biotechnologies, University of Naples “Federico II”, Naples, Italy
- Istituto per l’ endocrinologia e l’oncologia “Gaetano Salvatore” (IEOS)-Centro Nazionale delle Ricerche (CNR), Naples, Italy
| | - Concetta Ambrosino
- Biogem, Istituto di Biologia e Genetica Molecolare, Ariano Irpino, Italy
- Department of Science and Technology, University of Sannio, Benevento, Italy
- Istituto per l’ endocrinologia e l’oncologia “Gaetano Salvatore” (IEOS)-Centro Nazionale delle Ricerche (CNR), Naples, Italy
- *Correspondence: Concetta Ambrosino,
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26
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Sánchez-Calabuig MJ, Fernández-González R, Hamdi M, Smits K, López-Cardona AP, Serres C, Macías-García B, Gutiérrez-Adán A. A high glucose concentration during early stages of in vitro equine embryo development alters expression of genes involved in glucose metabolism. Equine Vet J 2020; 53:787-795. [PMID: 32881040 DOI: 10.1111/evj.13342] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 07/17/2020] [Accepted: 08/27/2020] [Indexed: 01/30/2023]
Abstract
BACKGROUND Equine embryos exhibit an unusual pattern of glucose tolerance in vitro and are currently cultured in hyperglycaemic conditions. OBJECTIVE Our main objective was to analyse the effect of different glucose concentrations on in vitro-produced equine embryo development and quality. STUDY DESIGN Experiments comparing in vitro and in vivo produced embryos. METHODS Oocytes (n = 641) were collected from post-mortem ovaries, matured in vitro and fertilised by intracytoplasmic sperm injection (ICSI). Embryo culture was divided from Day 0 to Day 4 and from Day 4 to Day 9 in three groups: 5-10 (5 and 10 mmol/L glucose respectively; n = 87); 5-17 (5 and 17.5 mmol/L; n = 66); and 10-17 (10 and 17.5 mmol/L; n = 117). A control group of 20 in vivo produced blastocysts was included. Cleavage and blastocyst rates were evaluated and embryos were snap-frozen for analysis of the relative mRNA expression of genes related to mitochondrial function, DNA methylation, apoptosis, glucose transport and metabolism. RESULTS No differences were observed in the cleavage or blastocyst rates among in vitro groups. Under high glucose conditions in vitro (10-17 group), BAX/BCL2 was higher, and PFKP, LDHA and COX2 were overexpressed compared to all other groups. The two groups with 5 mmol/L glucose concentration during the first culture stage (5-10 and 5-17) displayed similar patterns which differed to the 10-17 group. MAIN LIMITATIONS Conclusions related to embryo quality are based on gene expression patterns. Transfer of in vitro-produced embryos would reveal whether the observed differences improve embryo developmental competence. CONCLUSIONS Five mM glucose during the first days of culture seems to be preferable to avoid over-activation of embryonic glycolytic pathways. Further studies are necessary to determine whether this improves embryo developmental competence.
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Affiliation(s)
- María J Sánchez-Calabuig
- Department of Animal Medicine and Surgery, Faculty of Veterinary Science, University Complutense of Madrid, Madrid, Spain.,Department of Animal Reproduction, INIA, Madrid, Spain
| | | | - Meriem Hamdi
- Department of Animal Reproduction, INIA, Madrid, Spain
| | - Katrien Smits
- Department of Obstetrics, Reproduction and Herd Health, Ghent University, Ghent, Belgium
| | - Angela P López-Cardona
- Department of Animal Reproduction, INIA, Madrid, Spain.,Grupo de Investigación (GI) - Biogénesis, Universidad de Antioquia, Medellín, Colombia
| | - Consuelo Serres
- Department of Animal Medicine and Surgery, Faculty of Veterinary Science, University Complutense of Madrid, Madrid, Spain
| | - Beatriz Macías-García
- Animal Medicine Department, Faculty of Veterinary Sciences, University of Extremadura, Cáceres, Spain.,Research Group of Intracellular Signalling and Technology of Reproduction (SINTREP), Research Institute of Biotechnology in Livestock and Cynegetic (INBIO G+C), University of Extremadura, Cáceres, Spain
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27
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de Lima CB, Sirard MA. Mitoepigenetics: Methylation of mitochondrial DNA is strand-biased in bovine oocytes and embryos. Reprod Domest Anim 2020; 55:1455-1458. [PMID: 32738169 DOI: 10.1111/rda.13786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/22/2020] [Indexed: 12/18/2022]
Abstract
Global mitochondrial DNA (mtDNA) methylation has been recently described in bovine and showed particular signatures in both gametes and embryos. Here, we investigated the distribution of mtDNA methylation through strand-specific mapping of methylation sites to gain perspective on how epigenetic mechanisms can be involved in mitochondrial function. We demonstrate that in both oocytes and embryos, the frequency of methylation is biased towards the light strand (L-strand), particularly in the gene bodies and in the region containing the L-strand promoter (LSP). Methylation is not restricted to CpG nucleotides and is not symmetrical on both strands. This configuration reinforces the hypothesis of a specific epigenetic regulation of mtDNA, which is an important observation for the understanding of how mitochondrial function is regulated.
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Affiliation(s)
- Camila Bruna de Lima
- Département des Sciences Animales, Centre de Recherche en Reproduction Développement et Santé Intergénérationnelle (CRDSI), Université Laval, Québec, QC, Canada
| | - Marc-André Sirard
- Département des Sciences Animales, Centre de Recherche en Reproduction Développement et Santé Intergénérationnelle (CRDSI), Université Laval, Québec, QC, Canada
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28
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Milazzotto MP, de Lima CB, da Fonseca AM, dos Santos EC, Ispada J. Erasing gametes to write blastocysts: metabolism as the new player in epigenetic reprogramming. Anim Reprod 2020; 17:e20200015. [PMID: 33029209 PMCID: PMC7534565 DOI: 10.1590/1984-3143-ar2020-0015] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/23/2020] [Indexed: 12/13/2022] Open
Abstract
Understanding preimplantation embryonic development is crucial for the improvement of assisted reproductive technologies and animal production. To achieve this goal, it is important to consider that gametes and embryos are highly susceptible to environmental changes. Beyond the metabolic adaptation, the dynamic status imposed during follicular growth and early embryogenesis may create marks that will guide the molecular regulation during prenatal development, and consequently impact the offspring phenotype. In this context, metaboloepigenetics has gained attention, as it investigates the crosstalk between metabolism and molecular control, i.e., how substrates generated by metabolic pathways may also act as players of epigenetic modifications. In this review, we present the main metabolic and epigenetic events of pre-implantation development, and how these systems connect to open possibilities for targeted manipulation of reproductive technologies and animal production systems.
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Affiliation(s)
- Marcella Pecora Milazzotto
- Laboratório de Epigenética e Metabolismo Embrionário, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brasil
- Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Camila Bruna de Lima
- Laboratório de Epigenética e Metabolismo Embrionário, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brasil
- Département des Sciences Animales, Centre de Recherche en Reproduction, Développement et Santé Intergénérationnelle, Faculté des Sciences de l’Agriculture et de l’Alimentation, Université Laval, Quebec, Canada
| | - Aldcejam Martins da Fonseca
- Laboratório de Epigenética e Metabolismo Embrionário, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brasil
| | - Erika Cristina dos Santos
- Laboratório de Epigenética e Metabolismo Embrionário, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brasil
| | - Jessica Ispada
- Laboratório de Epigenética e Metabolismo Embrionário, Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brasil
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29
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Chiaratti MR, Macabelli CH, Augusto Neto JD, Grejo MP, Pandey AK, Perecin F, Collado MD. Maternal transmission of mitochondrial diseases. Genet Mol Biol 2020; 43:e20190095. [PMID: 32141474 PMCID: PMC7197987 DOI: 10.1590/1678-4685-gmb-2019-0095] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 11/01/2019] [Indexed: 12/19/2022] Open
Abstract
Given the major role of the mitochondrion in cellular homeostasis, dysfunctions of this organelle may lead to several common diseases in humans. Among these, maternal diseases linked to mitochondrial DNA (mtDNA) mutations are of special interest due to the unclear pattern of mitochondrial inheritance. Multiple copies of mtDNA are present in a cell, each encoding for 37 genes essential for mitochondrial function. In cases of mtDNA mutations, mitochondrial malfunctioning relies on mutation load, as mutant and wild-type molecules may co-exist within the cell. Since the mutation load associated with disease manifestation varies for different mutations and tissues, it is hard to predict the progeny phenotype based on mutation load in the progenitor. In addition, poorly understood mechanisms act in the female germline to prevent the accumulation of deleterious mtDNA in the following generations. In this review, we outline basic aspects of mitochondrial inheritance in mammals and how they may lead to maternally-inherited diseases. Furthermore, we discuss potential therapeutic strategies for these diseases, which may be used in the future to prevent their transmission.
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Affiliation(s)
- Marcos R Chiaratti
- Universidade Federal de São Carlos, Departamento de Genética e Evolução, Laboratório de Genética e Biotecnologia, São Carlos, SP, Brazil
| | - Carolina H Macabelli
- Universidade Federal de São Carlos, Departamento de Genética e Evolução, Laboratório de Genética e Biotecnologia, São Carlos, SP, Brazil
| | - José Djaci Augusto Neto
- Universidade Federal de São Carlos, Departamento de Genética e Evolução, Laboratório de Genética e Biotecnologia, São Carlos, SP, Brazil
| | - Mateus Priolo Grejo
- Universidade Federal de São Carlos, Departamento de Genética e Evolução, Laboratório de Genética e Biotecnologia, São Carlos, SP, Brazil
| | - Anand Kumar Pandey
- Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana, India
| | - Felipe Perecin
- Universidade de São Paulo, Faculdade de Zootecnia e Engenharia de Alimentos, Departamento de Medicina Veterinária, Laboratório de Morfofisiologia Molecular e Desenvolvimento, Pirassununga, SP, Brazil
| | - Maite Del Collado
- Universidade de São Paulo, Faculdade de Zootecnia e Engenharia de Alimentos, Departamento de Medicina Veterinária, Laboratório de Morfofisiologia Molecular e Desenvolvimento, Pirassununga, SP, Brazil
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30
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Morris MJ, Hesson LB, Youngson NA. Non-CpG methylation biases bisulphite PCR towards low or unmethylated mitochondrial DNA: recommendations for the field. ENVIRONMENTAL EPIGENETICS 2020; 6:dvaa001. [PMID: 32154030 PMCID: PMC7055202 DOI: 10.1093/eep/dvaa001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 05/04/2023]
Abstract
Mitochondrial DNA (mtDNA) is a circular genome of 16 kb that is present in multiple copies in mitochondria. mtDNA codes for genes that contribute to mitochondrial structure and function. A long-standing question has asked whether mtDNA is epigenetically regulated similarly to the nuclear genome. Recently published data suggest that unlike the nuclear genome where CpG methylation is the norm, mtDNA is methylated predominantly at non-CpG cytosines. This raises important methodological considerations for future investigations. In particular, existing bisulphite PCR techniques may be unsuitable due to primers being biased towards amplification from unmethylated mtDNA. Here, we describe how this may have led to previous studies underestimating the level of mtDNA methylation and reiterate methodological strategies for its accurate assessment.
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Affiliation(s)
| | - Luke B Hesson
- Prince of Wales Clinical School and Lowy Cancer Research Centre, UNSW Sydney, NSW 2052, Australia
| | - Neil A Youngson
- School of Medical Sciences, UNSW Sydney, NSW 2052, Australia
- The Institute of Hepatology, Foundation for Liver Research, London, SE5 9NT, UK
- Faculty of Life Sciences and Medicine, King’s College London, London, UK
- Correspondence address. The Institute of Hepatology, Foundation for Liver Research, London, UK. Tel : +44 (0)20 7255 9835; E-mail:
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31
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Genomic Balance: Two Genomes Establishing Synchrony to Modulate Cellular Fate and Function. Cells 2019; 8:cells8111306. [PMID: 31652817 PMCID: PMC6912345 DOI: 10.3390/cells8111306] [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: 10/02/2019] [Revised: 10/17/2019] [Accepted: 10/22/2019] [Indexed: 01/21/2023] Open
Abstract
It is becoming increasingly apparent that cells require cooperation between the nuclear and mitochondrial genomes to promote effective function. However, it was long thought that the mitochondrial genome was under the strict control of the nuclear genome and the mitochondrial genome had little influence on cell fate unless it was extensively mutated, as in the case of the mitochondrial DNA diseases. However, as our understanding of the roles that epigenetic regulators, including DNA methylation, and metabolism play in cell fate and function, the role of the mitochondrial genome appears to have a greater influence than previously thought. In this review, I draw on examples from tumorigenesis, stem cells, and oocyte pre- and post-fertilisation events to discuss how modulating one genome affects the other and that this results in a compromise to produce functional mature cells. I propose that, during development, both of the genomes interact with each other through intermediaries to establish genomic balance and that establishing genomic balance is a key facet in determining cell fate and viability.
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