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Shao Z, Han Y, Zhou D. Optimized bisulfite sequencing analysis reveals the lack of 5-methylcytosine in mammalian mitochondrial DNA. BMC Genomics 2023; 24:439. [PMID: 37542258 PMCID: PMC10403921 DOI: 10.1186/s12864-023-09541-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 07/27/2023] [Indexed: 08/06/2023] Open
Abstract
BACKGROUND DNA methylation is one of the best characterized epigenetic modifications in the mammalian nuclear genome and is known to play a significant role in various biological processes. Nonetheless, the presence of 5-methylcytosine (5mC) in mitochondrial DNA remains controversial, as data ranging from the lack of 5mC to very extensive 5mC have been reported. RESULTS By conducting comprehensive bioinformatic analyses of both published and our own data, we reveal that previous observations of extensive and strand-biased mtDNA-5mC are likely artifacts due to a combination of factors including inefficient bisulfite conversion, extremely low sequencing reads in the L strand, and interference from nuclear mitochondrial DNA sequences (NUMTs). To reduce false positive mtDNA-5mC signals, we establish an optimized procedure for library preparation and data analysis of bisulfite sequencing. Leveraging our modified workflow, we demonstrate an even distribution of 5mC signals across the mtDNA and an average methylation level ranging from 0.19% to 0.67% in both cell lines and primary cells, which is indistinguishable from the background noise. CONCLUSIONS We have developed a framework for analyzing mtDNA-5mC through bisulfite sequencing, which enables us to present multiple lines of evidence for the lack of extensive 5mC in mammalian mtDNA. We assert that the data available to date do not support the reported presence of mtDNA-5mC.
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Affiliation(s)
- Zhenyu Shao
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Yang Han
- Shanghai Key Laboratory of Medical Epigenetics, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University & Chinese Academy of Medical Sciences (RU069), Shanghai, 200032, China
| | - Dan Zhou
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Shanghai Key Laboratory of Medical Epigenetics, Institutes of Biomedical Sciences, Shanghai Medical College of Fudan University & Chinese Academy of Medical Sciences (RU069), Shanghai, 201399, China.
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2
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Borah S, Mishra R, Dey S, Suchanti S, Bhowmick NA, Giri B, Haldar S. Prognostic Value of Circulating Mitochondrial DNA in Prostate Cancer and Underlying Mechanism. Mitochondrion 2023; 71:40-49. [PMID: 37211294 DOI: 10.1016/j.mito.2023.05.005] [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: 01/09/2023] [Revised: 04/03/2023] [Accepted: 05/14/2023] [Indexed: 05/23/2023]
Abstract
Circulating DNAs are considered as degraded DNA fragments of approximately 50-200 bp, found in blood plasma, consisting of cell-free mitochondrial and nuclear DNA. Such cell-free DNAs in the blood are found to be altered in different pathological conditions including lupus, heart disease, and malignancies. While nuclear DNAs are being used and being developed as a powerful clinical biomarker in liquid biopsies, mitochondrial DNAs (mtDNAs) are associated with inflammatory conditions including cancer progression. Patients with cancer including prostate cancer are found to have measurable concentrations of mitochondrial DNA in circulation in comparison with healthy controls. The plasma content of mitochondrial DNA is dramatically elevated in both prostate cancer patients and mouse models treated with the chemotherapeutic drug. Cell-free mtDNA, in its oxidized form, induced a pro-inflammatory condition and activates NLRP3-mediated inflammasome formation which causes IL-1β-mediated activation of growth factors. On the other hand, interacting with TLR9, mtDNAs trigger NF-κB-mediated complement C3a positive feedback paracrine loop and activate pro-proliferating signaling through upregulating AKT, ERK, and Bcl2 in the prostate tumor microenvironment. In this review, we discuss the growing evidence supporting cell-free mitochondrial DNA copy number, size, and mutations in mtDNA genes as potential prognostic biomarkers in different cancers and targetable prostate cancer therapeutic candidates impacting stromal-epithelial interactions essential for chemotherapy response.
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Affiliation(s)
- Supriya Borah
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles 90048, CA, USA
| | - Rajeev Mishra
- Department of Life Sciences, CSJM University, Kanpur, Uttar Pradesh 208012, India
| | - Sananda Dey
- Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Surabhi Suchanti
- Department of Biosciences, Manipal University Jaipur, Rajasthan 303007, India
| | - Neil A Bhowmick
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles 90048, CA, USA; Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Biplab Giri
- Department of Physiology, University of Gour Banga, Malda 732103, India.
| | - Subhash Haldar
- Department of Biochemistry, Bose Institute, Kolkata 700091, India.
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3
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Wagner A, Kosnacova H, Chovanec M, Jurkovicova D. Mitochondrial Genetic and Epigenetic Regulations in Cancer: Therapeutic Potential. Int J Mol Sci 2022; 23:ijms23147897. [PMID: 35887244 PMCID: PMC9321253 DOI: 10.3390/ijms23147897] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/12/2022] [Accepted: 07/14/2022] [Indexed: 02/01/2023] Open
Abstract
Mitochondria are dynamic organelles managing crucial processes of cellular metabolism and bioenergetics. Enabling rapid cellular adaptation to altered endogenous and exogenous environments, mitochondria play an important role in many pathophysiological states, including cancer. Being under the control of mitochondrial and nuclear DNA (mtDNA and nDNA), mitochondria adjust their activity and biogenesis to cell demands. In cancer, numerous mutations in mtDNA have been detected, which do not inactivate mitochondrial functions but rather alter energy metabolism to support cancer cell growth. Increasing evidence suggests that mtDNA mutations, mtDNA epigenetics and miRNA regulations dynamically modify signalling pathways in an altered microenvironment, resulting in cancer initiation and progression and aberrant therapy response. In this review, we discuss mitochondria as organelles importantly involved in tumorigenesis and anti-cancer therapy response. Tumour treatment unresponsiveness still represents a serious drawback in current drug therapies. Therefore, studying aspects related to genetic and epigenetic control of mitochondria can open a new field for understanding cancer therapy response. The urgency of finding new therapeutic regimens with better treatment outcomes underlines the targeting of mitochondria as a suitable candidate with new therapeutic potential. Understanding the role of mitochondria and their regulation in cancer development, progression and treatment is essential for the development of new safe and effective mitochondria-based therapeutic regimens.
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Affiliation(s)
- Alexandra Wagner
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, 845 05 Bratislava, Slovakia; (A.W.); (H.K.); (M.C.)
- Department of Simulation and Virtual Medical Education, Faculty of Medicine, Comenius University, 811 08 Bratislava, Slovakia
| | - Helena Kosnacova
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, 845 05 Bratislava, Slovakia; (A.W.); (H.K.); (M.C.)
- Department of Simulation and Virtual Medical Education, Faculty of Medicine, Comenius University, 811 08 Bratislava, Slovakia
| | - Miroslav Chovanec
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, 845 05 Bratislava, Slovakia; (A.W.); (H.K.); (M.C.)
| | - Dana Jurkovicova
- Department of Genetics, Cancer Research Institute, Biomedical Research Center, Slovak Academy of Sciences, 845 05 Bratislava, Slovakia; (A.W.); (H.K.); (M.C.)
- Correspondence:
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4
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Rautenberg EK, Hamzaoui Y, Coletta DK. Mini-review: Mitochondrial DNA methylation in type 2 diabetes and obesity. Front Endocrinol (Lausanne) 2022; 13:968268. [PMID: 36093112 PMCID: PMC9453027 DOI: 10.3389/fendo.2022.968268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 08/11/2022] [Indexed: 11/13/2022] Open
Abstract
Type 2 diabetes (T2D) and obesity are two of the most challenging public health problems of our time. Therefore, understanding the molecular mechanisms that contribute to these complex metabolic disorders is essential. An underlying pathophysiological condition of T2D and obesity is insulin resistance (IR), a reduced biological response to insulin in peripheral tissues such as the liver, adipose tissue, and skeletal muscle. Many factors contribute to IR, including lifestyle variables such as a high-fat diet and physical inactivity, genetics, and impaired mitochondrial function. It is well established that impaired mitochondria structure and function occur in insulin-resistant skeletal muscle volunteers with T2D or obesity. Therefore, it could be hypothesized that the mitochondrial abnormalities are due to epigenetic regulation of mitochondrial and nuclear-encoded genes that code for mitochondrial structure and function. In this review, we describe the normal function and structure of mitochondria and highlight some of the key studies that demonstrate mitochondrial abnormalities in skeletal muscle of volunteers with T2D and obesity. Additionally, we describe epigenetic modifications in the context of IR and mitochondrial abnormalities, emphasizing mitochondria DNA (mtDNA) methylation, an emerging area of research.
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Affiliation(s)
- Emma K. Rautenberg
- Department of Physiology, The University of Arizona College of Medicine, Tucson, AZ, United States
| | - Yassin Hamzaoui
- Department of Physiology, The University of Arizona College of Medicine, Tucson, AZ, United States
| | - Dawn K. Coletta
- Department of Physiology, The University of Arizona College of Medicine, Tucson, AZ, United States
- Department of Medicine, Division of Endocrinology, The University of Arizona College of Medicine, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity and Metabolism, The University of Arizona, Tucson, AZ, United States
- *Correspondence: Dawn K. Coletta,
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5
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Czegle I, Gray AL, Wang M, Liu Y, Wang J, Wappler-Guzzetta EA. Mitochondria and Their Relationship with Common Genetic Abnormalities in Hematologic Malignancies. Life (Basel) 2021; 11:1351. [PMID: 34947882 PMCID: PMC8707674 DOI: 10.3390/life11121351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/29/2021] [Accepted: 11/29/2021] [Indexed: 11/16/2022] Open
Abstract
Hematologic malignancies are known to be associated with numerous cytogenetic and molecular genetic changes. In addition to morphology, immunophenotype, cytochemistry and clinical characteristics, these genetic alterations are typically required to diagnose myeloid, lymphoid, and plasma cell neoplasms. According to the current World Health Organization (WHO) Classification of Tumors of Hematopoietic and Lymphoid Tissues, numerous genetic changes are highlighted, often defining a distinct subtype of a disease, or providing prognostic information. This review highlights how these molecular changes can alter mitochondrial bioenergetics, cell death pathways, mitochondrial dynamics and potentially be related to mitochondrial genetic changes. A better understanding of these processes emphasizes potential novel therapies.
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Affiliation(s)
- Ibolya Czegle
- Department of Internal Medicine and Haematology, Semmelweis University, H-1085 Budapest, Hungary;
| | - Austin L. Gray
- Department of Pathology and Laboratory Medicine, Loma Linda University Health, Loma Linda, CA 92354, USA; (A.L.G.); (Y.L.); (J.W.)
| | - Minjing Wang
- Independent Researcher, Diamond Bar, CA 91765, USA;
| | - Yan Liu
- Department of Pathology and Laboratory Medicine, Loma Linda University Health, Loma Linda, CA 92354, USA; (A.L.G.); (Y.L.); (J.W.)
| | - Jun Wang
- Department of Pathology and Laboratory Medicine, Loma Linda University Health, Loma Linda, CA 92354, USA; (A.L.G.); (Y.L.); (J.W.)
| | - Edina A. Wappler-Guzzetta
- Department of Pathology and Laboratory Medicine, Loma Linda University Health, Loma Linda, CA 92354, USA; (A.L.G.); (Y.L.); (J.W.)
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6
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Cao K, Feng Z, Gao F, Zang W, Liu J. Mitoepigenetics: An intriguing regulatory layer in aging and metabolic-related diseases. Free Radic Biol Med 2021; 177:337-346. [PMID: 34715295 DOI: 10.1016/j.freeradbiomed.2021.10.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/06/2021] [Accepted: 10/22/2021] [Indexed: 12/20/2022]
Abstract
As a key organelle in eukaryotic cells, mitochondria play a central role in maintaining normal cellular functions. Mitochondrial dysfunction is reported to be closely related with aging and various diseases. Epigenetic modifications in nuclear genome provide a substantial layer for the modulation of nuclear-encoded gene expression. However, whether mitochondria could also be subjected to such similar epigenetic alterations and the involved mechanisms remain largely obscure and controversial. Recently, accumulating evidence has suggested that mitochondrial epigenetics, also known as mitoepigenetics may serve as an intriguing regulatory layer in mitochondrial DNA (mtDNA)-encoded gene expression. Given the potential regulatory role of mitoepigenetics, mitochondrial dysfunction derived from mitoepigenetics-induced abnormal gene expression could also be closely associated with aging and disease development. In this review, we summarized the recent advances in mitoepigenetics, with a special focus on mtDNA methylation in aging and metabolic-related diseases as well as the new methods and technologies for the study of mitoepigenetics. Uncovering the regulatory role of mitoepigenetics will help to understand the underlying mechanisms of mitochondrial dysfunction and provide novel strategies for delaying aging and preventing metabolic-related diseases.
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Affiliation(s)
- Ke Cao
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Zhihui Feng
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, China; Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Feng Gao
- School of Aerospace Medicine, Fourth Military Medical University, Xi'an, 710032, China
| | - Weijin Zang
- Department of Pharmacology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, China
| | - Jiankang Liu
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, China; University of Health and Rehabilitation Sciences, Qingdao, 266071, China.
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7
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Cao K, Lv W, Wang X, Dong S, Liu X, Yang T, Xu J, Zeng M, Zou X, Zhao D, Ma Q, Lin M, Long J, Zang W, Gao F, Feng Z, Liu J. Hypermethylation of Hepatic Mitochondrial ND6 Provokes Systemic Insulin Resistance. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2004507. [PMID: 34141522 PMCID: PMC8188198 DOI: 10.1002/advs.202004507] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/18/2021] [Indexed: 05/10/2023]
Abstract
Mitochondrial epigenetics is rising as intriguing notion for its potential involvement in aging and diseases, while the details remain largely unexplored. Here it is shown that among the 13 mitochondrial DNA (mtDNA) encoded genes, NADH-dehydrogenase 6 (ND6) transcript is primarily decreased in obese and type 2 diabetes populations, which negatively correlates with its distinctive hypermethylation. Hepatic mtDNA sequencing in mice unveils that ND6 presents the highest methylation level, which dramatically increases under diabetic condition due to enhanced mitochondrial translocation of DNA methyltransferase 1 (DNMT1) promoted by free fatty acid through adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) activation. Hepatic knockdown of ND6 or overexpression of Dnmt1 similarly impairs mitochondrial function and induces systemic insulin resistance both in vivo and in vitro. Genetic or chemical targeting hepatic DNMT1 shows significant benefits against insulin resistance associated metabolic disorders. These findings highlight the pivotal role of ND6 epigenetic network in regulating mitochondrial function and onset of insulin resistance, shedding light on potential preventive and therapeutic strategies of insulin resistance and related metabolic disorders from a perspective of mitochondrial epigenetics.
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Affiliation(s)
- Ke Cao
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Weiqiang Lv
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Xueqiang Wang
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Shanshan Dong
- Biomedical Informatics & Genomics CenterThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShannxi710049China
| | - Xuyun Liu
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Tielin Yang
- Biomedical Informatics & Genomics CenterThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShannxi710049China
| | - Jie Xu
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Mengqi Zeng
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Xuan Zou
- National & Local Joint Engineering Research Center of Biodiagnosis and BiotherapyThe Second Affiliated Hospital of Xi'an Jiaotong UniversityXi'anShannxi710004China
| | - Daina Zhao
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Qingqing Ma
- Guizhou Aerospace HospitalZunyiGuizhou563099China
| | - Mu Lin
- Guizhou Aerospace HospitalZunyiGuizhou563099China
| | - Jiangang Long
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Weijin Zang
- Department of PharmacologySchool of Basic Medical SciencesXi'an Jiaotong University Health Science CenterXi'anShaanxi710061China
| | - Feng Gao
- School of Aerospace MedicineFourth Military Medical UniversityXi'an710032China
| | - Zhihui Feng
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
- Frontier Institute of Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
| | - Jiankang Liu
- Center for Mitochondrial Biology and MedicineThe Key Laboratory of Biomedical Information Engineering of Ministry of EducationSchool of Life Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
- Frontier Institute of Science and TechnologyXi'an Jiaotong UniversityXi'anShaanxi710049China
- National & Local Joint Engineering Research Center of Biodiagnosis and BiotherapyThe Second Affiliated Hospital of Xi'an Jiaotong UniversityXi'anShannxi710004China
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8
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Mitochondrial DNA Methylation and Human Diseases. Int J Mol Sci 2021; 22:ijms22094594. [PMID: 33925624 PMCID: PMC8123858 DOI: 10.3390/ijms22094594] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/23/2021] [Accepted: 04/25/2021] [Indexed: 12/12/2022] Open
Abstract
Epigenetic modifications of the nuclear genome, including DNA methylation, histone modifications and non-coding RNA post-transcriptional regulation, are increasingly being involved in the pathogenesis of several human diseases. Recent evidence suggests that also epigenetic modifications of the mitochondrial genome could contribute to the etiology of human diseases. In particular, altered methylation and hydroxymethylation levels of mitochondrial DNA (mtDNA) have been found in animal models and in human tissues from patients affected by cancer, obesity, diabetes and cardiovascular and neurodegenerative diseases. Moreover, environmental factors, as well as nuclear DNA genetic variants, have been found to impair mtDNA methylation patterns. Some authors failed to find DNA methylation marks in the mitochondrial genome, suggesting that it is unlikely that this epigenetic modification plays any role in the control of the mitochondrial function. On the other hand, several other studies successfully identified the presence of mtDNA methylation, particularly in the mitochondrial displacement loop (D-loop) region, relating it to changes in both mtDNA gene transcription and mitochondrial replication. Overall, investigations performed until now suggest that methylation and hydroxymethylation marks are present in the mtDNA genome, albeit at lower levels compared to those detectable in nuclear DNA, potentially contributing to the mitochondria impairment underlying several human diseases.
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9
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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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10
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Nikolac Perkovic M, Videtic Paska A, Konjevod M, Kouter K, Svob Strac D, Nedic Erjavec G, Pivac N. Epigenetics of Alzheimer's Disease. Biomolecules 2021; 11:biom11020195. [PMID: 33573255 PMCID: PMC7911414 DOI: 10.3390/biom11020195] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/19/2021] [Accepted: 01/26/2021] [Indexed: 02/07/2023] Open
Abstract
There are currently no validated biomarkers which can be used to accurately diagnose Alzheimer’s disease (AD) or to distinguish it from other dementia-causing neuropathologies. Moreover, to date, only symptomatic treatments exist for this progressive neurodegenerative disorder. In the search for new, more reliable biomarkers and potential therapeutic options, epigenetic modifications have emerged as important players in the pathogenesis of AD. The aim of the article was to provide a brief overview of the current knowledge regarding the role of epigenetics (including mitoepigenetics) in AD, and the possibility of applying these advances for future AD therapy. Extensive research has suggested an important role of DNA methylation and hydroxymethylation, histone posttranslational modifications, and non-coding RNA regulation (with the emphasis on microRNAs) in the course and development of AD. Recent studies also indicated mitochondrial DNA (mtDNA) as an interesting biomarker of AD, since dysfunctions in the mitochondria and lower mtDNA copy number have been associated with AD pathophysiology. The current evidence suggests that epigenetic changes can be successfully detected, not only in the central nervous system, but also in the cerebrospinal fluid and on the periphery, contributing further to their potential as both biomarkers and therapeutic targets in AD.
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Affiliation(s)
- Matea Nikolac Perkovic
- Laboratory for Molecular Neuropsychiatry, Division of Molecular Medicine, Ruder Boskovic Institute, HR-10000 Zagreb, Croatia; (M.N.P.); (M.K.); (D.S.S.); (G.N.E.)
| | - Alja Videtic Paska
- Medical Center for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (A.V.P.); (K.K.)
| | - Marcela Konjevod
- Laboratory for Molecular Neuropsychiatry, Division of Molecular Medicine, Ruder Boskovic Institute, HR-10000 Zagreb, Croatia; (M.N.P.); (M.K.); (D.S.S.); (G.N.E.)
| | - Katarina Kouter
- Medical Center for Molecular Biology, Institute of Biochemistry and Molecular Genetics, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; (A.V.P.); (K.K.)
| | - Dubravka Svob Strac
- Laboratory for Molecular Neuropsychiatry, Division of Molecular Medicine, Ruder Boskovic Institute, HR-10000 Zagreb, Croatia; (M.N.P.); (M.K.); (D.S.S.); (G.N.E.)
| | - Gordana Nedic Erjavec
- Laboratory for Molecular Neuropsychiatry, Division of Molecular Medicine, Ruder Boskovic Institute, HR-10000 Zagreb, Croatia; (M.N.P.); (M.K.); (D.S.S.); (G.N.E.)
| | - Nela Pivac
- Laboratory for Molecular Neuropsychiatry, Division of Molecular Medicine, Ruder Boskovic Institute, HR-10000 Zagreb, Croatia; (M.N.P.); (M.K.); (D.S.S.); (G.N.E.)
- Correspondence: ; Tel.: +38-514-571-207
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11
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F C Lopes A. Mitochondrial metabolism and DNA methylation: a review of the interaction between two genomes. Clin Epigenetics 2020; 12:182. [PMID: 33228792 PMCID: PMC7684747 DOI: 10.1186/s13148-020-00976-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/10/2020] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are controlled by the coordination of two genomes: the mitochondrial and the nuclear DNA. As such, variations in nuclear gene expression as a consequence of mutations and epigenetic modifications can affect mitochondrial functionality. Conversely, the opposite could also be true. However, the relationship between mitochondrial dysfunction and epigenetics, such as nuclear DNA methylation, remains largely unexplored.
Mitochondria function as central metabolic hubs controlling some of the main substrates involved in nuclear DNA methylation, via the one carbon metabolism, the tricarboxylic acid cycle and the methionine pathway. Here, we review key findings and highlight new areas of focus, with the ultimate goal of getting one step closer to understanding the genomic effects of mitochondrial dysfunction on nuclear epigenetic landscapes.
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Affiliation(s)
- Amanda F C Lopes
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK. .,Medical Research Council - Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK.
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12
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Zhu X, Xuan Z, Chen J, Li Z, Zheng S, Song P. How DNA methylation affects the Warburg effect. Int J Biol Sci 2020; 16:2029-2041. [PMID: 32549751 PMCID: PMC7294934 DOI: 10.7150/ijbs.45420] [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: 02/28/2020] [Accepted: 04/05/2020] [Indexed: 12/13/2022] Open
Abstract
Significant enhancement of the glycolysis pathway is a major feature of tumor cells, even in the presence of abundant oxygen; this enhancement is known as the Warburg effect, and also called aerobic glycolysis. The Warburg effect was discovered nearly a hundred years ago, but its specific mechanism remains difficult to explain. DNA methylation is considered to be a potential trigger for the Warburg effect, as the two processes have many overlapping links during tumorigenesis. Based on a widely recognized potential mechanism of the Warburg effect, we here summarized the relationship between DNA methylation and the Warburg effect with regard to cellular energy metabolism factors, such as glycolysis related enzymes, mitochondrial function, glycolysis bypass pathways, the tumor oxygen sensing pathway and abnormal methylation conditions. We believe that clarifying the relationship between these different mechanisms may further help us understand how DNA methylation works on tumorigenesis and provide new opportunities for cancer therapy.
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Affiliation(s)
- Xingxin Zhu
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University.,NHC Key Laboratory of Combined Multi-organ Transplantation.,Key Laboratory of the diagnosis and treatment of organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019).,Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou 310003, China
| | - Zefeng Xuan
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University.,NHC Key Laboratory of Combined Multi-organ Transplantation.,Key Laboratory of the diagnosis and treatment of organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019).,Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou 310003, China
| | - Jun Chen
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University.,NHC Key Laboratory of Combined Multi-organ Transplantation.,Key Laboratory of the diagnosis and treatment of organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019).,Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou 310003, China
| | - Zequn Li
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University.,NHC Key Laboratory of Combined Multi-organ Transplantation.,Key Laboratory of the diagnosis and treatment of organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019).,Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou 310003, China
| | - Shusen Zheng
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University.,NHC Key Laboratory of Combined Multi-organ Transplantation.,Key Laboratory of the diagnosis and treatment of organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019).,Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou 310003, China
| | - Penghong Song
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University.,NHC Key Laboratory of Combined Multi-organ Transplantation.,Key Laboratory of the diagnosis and treatment of organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment For Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019).,Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou 310003, China
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13
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Han W, Xue Q, Li G, Yin J, Zhang H, Zhu Y, Xing W, Cao Y, Su Y, Wang K, Zou J. Genome-wide analysis of the role of DNA methylation in inbreeding depression of reproduction in Langshan chicken. Genomics 2020; 112:2677-2687. [PMID: 32057912 DOI: 10.1016/j.ygeno.2020.02.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 02/01/2020] [Accepted: 02/07/2020] [Indexed: 12/18/2022]
Abstract
Inbreeding depression of chicken reproduction is a major concern in the conservation of chicken genetic resources. To investigate the potential DNA methylation sites involved in the inbreeding depression of chicken reproduction, we carried out whole-genome bisulfite sequencing (WGBS) of hypothalamus and ovary tissues from the strongly and weakly inbred Langshan chickens, respectively. 5948 and 4593 differentially methylated regions (DMRs) were identified in the hypothalamus and ovary between the strongly and weakly inbred Langshan chickens, respectively. Large numbers of DMR-related genes (DMGs) were enriched in reproduction-related pathways. By combining the WGBS and transcriptome data, two DMRs in SRD5A1 and CDC27 genes were inferred as the most likely biomarkers of inbreeding depression of reproduction in Langshan chicken. Our study provides the first systematic investigation of the DNA methylation changes in strongly inbred chickens, and extends our understanding of the regulatory mechanisms underlying inbreeding depression in chicken reproduction.
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Affiliation(s)
- Wei Han
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Qian Xue
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Guohui Li
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Jianmei Yin
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Huiyong Zhang
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Yunfen Zhu
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Weijie Xing
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Yuxia Cao
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Yijun Su
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China
| | - Kehua Wang
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China.
| | - Jianmin Zou
- National Chickens Genetic Resources, Poultry Institute, Chinese Academy of Agricultural Science, Yangzhou 225000, China.
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14
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Guo B, Yin J, Hao W, Jiao M. Polyurethane foam induces epigenetic modification of mitochondrial DNA during different metamorphic stages of Tenebrio molitor. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 183:109461. [PMID: 31377519 DOI: 10.1016/j.ecoenv.2019.109461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 07/13/2019] [Accepted: 07/19/2019] [Indexed: 06/10/2023]
Abstract
The present work investigated the changes in DNA methylation pattern of Tenebrio molitor mitochondria genome at different development stages, which was fed with polyurethane foam as a sole diet. Polyurethane foam could influence the global methylation levels in mitochondria DNA of Tenebrio molitor. Different leves of 5-methylcytosine appeared at CpG and non-CpG sites of Tenebrio molitor mtDNA while they were fed with polyurethane foam: 10 CpG and 49 non-CpG sites at larval stage, 4 CpG and 31 non-CpG sites at pupa stage, 7 CpG and 56 non-CpG sites at adult stage in general. Moreover, we observed the decreased levels of ATP generation with the mitochondria DNA methylation variation. The results demonstrated that mitochondria DNA gene could be methylated in response to environmental pollutants to modulate stage-specific functions. Moreover, mtDNA methylation of polyurethane-foam-feeding Tenebrio molitor existed discrepancy in the developmental stage. The tentative methylation mechanism of mtDNA might be that polyurethane foam induced oxidative stress and increased the permeability of mitochondrial membranes, which resulted in transmethylase entry into mitochondria.
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Affiliation(s)
- Baoyuan Guo
- Academy of National Food and Strategic Reserves Administration, China.
| | - Jing Yin
- Ying Da Chang An Insurance Brokers Group CO.,LTD, Beijing, 100052, China
| | - Weiyu Hao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Meng Jiao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
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15
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Dou X, Boyd-Kirkup JD, McDermott J, Zhang X, Li F, Rong B, Zhang R, Miao B, Chen P, Cheng H, Xue J, Bennett D, Wong J, Lan F, Han JDJ. The strand-biased mitochondrial DNA methylome and its regulation by DNMT3A. Genome Res 2019; 29:1622-1634. [PMID: 31537639 PMCID: PMC6771398 DOI: 10.1101/gr.234021.117] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 08/23/2019] [Indexed: 01/19/2023]
Abstract
How individual genes are regulated from a mitochondrial polycistronic transcript to have variable expression remains an enigma. Here, through bisulfite sequencing and strand-specific mapping, we show mitochondrial genomes in humans and other animals are strongly biased to light (L)-strand non-CpG methylation with conserved peak loci preferentially located at gene-gene boundaries, which was also independently validated by MeDIP and FspEI digestion. Such mtDNA methylation patterns are conserved across different species and developmental stages but display dynamic local or global changes during development and aging. Knockout of DNMT3A alone perturbed mtDNA regional methylation patterns, but not global levels, and altered mitochondrial gene expression, copy number, and oxygen respiration. Overexpression of DNMT3A strongly increased mtDNA methylation and strand bias. Overall, methylation at gene bodies and boundaries was negatively associated with mitochondrial transcript abundance and also polycistronic transcript processing. Furthermore, HPLC-MS confirmed the methylation signals on mitochondria DNA. Together, these data provide high-resolution mtDNA methylation maps that revealed a strand-specific non-CpG methylation, its dynamic regulation, and its impact on the polycistronic mitochondrial transcript processing.
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Affiliation(s)
- Xiaoyang Dou
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jerome D Boyd-Kirkup
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Joseph McDermott
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiaoli Zhang
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Center for Quantitative Biology (CQB), Peking University, Beijing 100871, China
| | - Fang Li
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Bowen Rong
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Key Laboratory of Epigenetics, Shanghai Ministry of Education, and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Rui Zhang
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Bisi Miao
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Key Laboratory of Epigenetics, Shanghai Ministry of Education, and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Peilin Chen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Hao Cheng
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jianhuang Xue
- The State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - David Bennett
- Rush Alzheimer's Disease Center, Rush University Medical Center, Chicago, Illinois 60612, USA
| | - Jiemin Wong
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Fei Lan
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Key Laboratory of Epigenetics, Shanghai Ministry of Education, and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Jing-Dong J Han
- Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Collaborative Innovation Center for Genetics and Developmental Biology, Chinese Academy of Sciences-Max Planck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Center for Quantitative Biology (CQB), Peking University, Beijing 100871, China
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16
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Fan LH, Wang ZB, Li QN, Meng TG, Dong MZ, Hou Y, Ouyang YC, Schatten H, Sun QY. Absence of mitochondrial DNA methylation in mouse oocyte maturation, aging and early embryo development. Biochem Biophys Res Commun 2019; 513:912-918. [PMID: 31005257 DOI: 10.1016/j.bbrc.2019.04.100] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 04/14/2019] [Indexed: 01/24/2023]
Abstract
Mitochondrial DNA (mtDNA) is important for oxidative phosphorylation; dysfunctions can play a role in many mitochondrial diseases and can also affect the aging of cells and individuals. DNA methylation is an important epigenetic modification that plays a critical role in regulating gene expression. While recent studies have revealed the existence of mtDNA methylation there are still controversies about mtDNA methylation due to the special structure of mtDNA. Mitochondria and DNA methylation are both essential for regulating oocyte maturation and early embryo development, but whether mtDNA methylation changes during this process is unknown. By employing bisulfite sequencing, we found that in the process of mouse oocyte maturation, postovulatory oocyte aging, and early embryo development, all analyzed mitochondrial genes, including 16S-CpGI, DCR, ND6, 12S, and ATP8, lacked 5'mC. Thus, mtDNA methylation does not occur in the oocyte and early embryo.
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Affiliation(s)
- Li-Hua Fan
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China; University of Chinese Academy of Sciences, Beijing, 100101, PR China
| | - Zhen-Bo Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China; University of Chinese Academy of Sciences, Beijing, 100101, PR China
| | - Qian-Nan Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China
| | - Tie-Gang Meng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China
| | - Ming-Zhe Dong
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China; University of Chinese Academy of Sciences, Beijing, 100101, PR China
| | - Yi Hou
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China
| | - Ying-Chun Ouyang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China
| | - Heide Schatten
- Department of Veterinary Pathobiology, University of Missouri, Columbia, MO, 65211, USA
| | - Qing-Yuan Sun
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, PR China; University of Chinese Academy of Sciences, Beijing, 100101, PR China.
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17
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Abstract
Epigenetics can be explored at different levels and can be divided into two major areas: epigenetics of nuclear-encoded DNA and epigenetics of mitochondrial-encoded DNA. In epigenetics of nuclear-encoded DNA, the main roles are played by DNA methylation, changes in histone structure and several types of non-coding RNAs. Mitochondrial epigenetics seems to be similar in the aspect of DNA methylation and to some extent in the role of non-coding RNAs but differs significantly in changes in components coiling DNA. Nuclear DNA is coiled around histones, but mitochondrial DNA, together with associated proteins, is located in mitochondrial pseudocompartments called nucleoids. It has been shown that mitochondrial epigenetic mechanisms influence cell fate, transcription regulation, cell division, cell cycle, physiological homeostasis, bioenergetics and even pathologies, but not all of these mechanisms have been explored in stem cells. The main issue is that most of these mechanisms have only recently been discovered in mitochondria, while improvements in methodology, especially next-generation sequencing, have enabled in-depth studies. Because studies exploring mitochondria from other aspects show that mitochondria are crucial for the normal behavior of stem cells, it is suggested that precise mitochondrial epigenetics in stem cells should be studied more intensively.
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18
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Mechta M, Ingerslev LR, Barrès R. Methodology for Accurate Detection of Mitochondrial DNA Methylation. J Vis Exp 2018:57772. [PMID: 29863674 PMCID: PMC6101301 DOI: 10.3791/57772] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Quantification of DNA methylation can be achieved using bisulfite sequencing, which takes advantage of the property of sodium bisulfite to convert unmethylated cytosine into uracil, in a single-stranded DNA context. Bisulfite sequencing can be targeted (using PCR) or performed on the whole genome and provides absolute quantification of cytosine methylation at the single base-resolution. Given the distinct nature of nuclear- and mitochondrial DNA, notably in the secondary structure, adaptions of bisulfite sequencing methods for investigating cytosine methylation in mtDNA should be made. Secondary and tertiary structure of mtDNA can indeed lead to bisulfite sequencing artifacts leading to false-positives due to incomplete denaturation poor access of bisulfite to single-stranded DNA. Here, we describe a protocol using an enzymatic digestion of DNA with BamHI coupled with bioinformatic analysis pipeline to allow accurate quantification of cytosine methylation levels in mtDNA. In addition, we provide guidelines for designing the bisulfite sequencing primers specific to mtDNA, in order to avoid targeting undesirable NUclear MiTochondrial segments (NUMTs) inserted into the nuclear genome.
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Affiliation(s)
- Mie Mechta
- The Novo Nordisk Foundation for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen
| | - Lars Roed Ingerslev
- The Novo Nordisk Foundation for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen
| | - Romain Barrès
- The Novo Nordisk Foundation for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen;
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19
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Accurate estimation of 5-methylcytosine in mammalian mitochondrial DNA. Sci Rep 2018; 8:5801. [PMID: 29643477 PMCID: PMC5895755 DOI: 10.1038/s41598-018-24251-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/28/2018] [Indexed: 02/06/2023] Open
Abstract
Whilst 5-methylcytosine (5mC) is a major epigenetic mark in the nuclear DNA in mammals, whether or not mitochondrial DNA (mtDNA) receives 5mC modification remains controversial. Herein, we exhaustively analysed mouse mtDNA using three methods that are based upon different principles for detecting 5mC. Next-generation bisulfite sequencing did not give any significant signatures of methylation in mtDNAs of liver, brain and embryonic stem cells (ESCs). Also, treatment with methylated cytosine-sensitive endonuclease McrBC resulted in no substantial decrease of mtDNA band intensities in Southern hybridisation. Furthermore, mass spectrometric nucleoside analyses of highly purified liver mtDNA preparations did not detect 5-methyldeoxycytidine at the levels found in the nuclear DNA but at a range of only 0.3-0.5% of deoxycytidine. Taken together, we propose that 5mC is not present at any specific region(s) of mtDNA and that levels of the methylated cytosine are fairly low, provided the modification occurs. It is thus unlikely that 5mC plays a universal role in mtDNA gene expression or mitochondrial metabolism.
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20
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Abstract
The rising toll of chronic and debilitating diseases brought about by the exposure to an ever expanding number of environmental pollutants and socio-economic factors is calling for action. The understanding of the molecular mechanisms behind the effects of environmental exposures can lead to the development of biomarkers that can support the public health fields of both early diagnosis and intervention to limit the burden of environmental diseases. The study of mitochondrial epigenetics carries high hopes to provide important biomarkers of exposure and disease. Mitochondria are in fact on the frontline of the cellular response to the environment. Modifications of the epigenetic factors regulating the mitochondrial activity are emerging as informative tools that can effectively report on the effects of the environment on the phenotype. Here, we will discuss the emerging field of mitochondrial epigenetics. This review describes the main epigenetic phenomena that modify the activity of the mitochondrial DNA including DNA methylation, long and short non-coding RNAs. We will discuss the unique pattern of mitochondrial DNA methylation, describe the challenges of correctly measuring it, and report on the existing studies that have analysed the correlation between environmental exposures and mitochondrial DNA methylation. Finally, we provide a brief account of the therapeutic approaches targeting mitochondria currently under consideration.
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Affiliation(s)
- Luca Lambertini
- Department of Preventive Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L. Levi Place, Box 1057, New York, NY, 10029, USA. .,Department of Obstetrics, Gynecology and Reproductive Science, Icahn School of Medicine at Mount Sinai, One Gustave L. Levi Place, Box 1057, New York, NY, 10029, USA.
| | - Hyang-Min Byun
- Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, Biomedical Research Building, Campus for Ageing and Vitality, Newcastle upon Tyne, UK.,Ageing Research Laboratory, Newcastle University, Campus for Ageing and Vitality, Edwardson Building, Newcastle upon Tyne, NE4 5PL, UK
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21
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More than a powerplant: the influence of mitochondrial transfer on the epigenome. CURRENT OPINION IN PHYSIOLOGY 2017; 3:16-24. [PMID: 29750205 DOI: 10.1016/j.cophys.2017.11.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Each cell in the human body, with the exception of red blood cells, contains multiple copies of mitochondria that house their own genetic material, the maternally inherited mitochondrial DNA. Mitochondria are the cell's powerplant due to their massive ATP generation. However, the mitochondrion is also a hub for metabolite production from the TCA cycle, fatty acid beta-oxidation, and ketogenesis. In addition to producing macromolecules for biosynthetic reactions and cell replication, several mitochondrial intermediate metabolites serve as cofactors or substrates for epigenome modifying enzymes that regulate chromatin structure and impact gene expression. Here, we discuss connections between mitochondrial metabolites and enzymatic writers and erasers of chromatin modifications. We do this from the unique perspective of cell-to-cell mitochondrial transfer and its potential impact on mitochondrial replacement therapies.
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22
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Messerlian C, Martinez RM, Hauser R, Baccarelli AA. 'Omics' and endocrine-disrupting chemicals - new paths forward. Nat Rev Endocrinol 2017; 13:740-748. [PMID: 28707677 PMCID: PMC7141602 DOI: 10.1038/nrendo.2017.81] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The emerging field of omics - large-scale data-rich biological measurements of the genome - provides new opportunities to advance and strengthen research into endocrine-disrupting chemicals (EDCs). Although some EDCs have been associated with adverse health effects in humans, our understanding of their impact remains incomplete. Progress in the field has been primarily limited by our inability to adequately estimate and characterize exposure and identify sensitive and measurable outcomes during windows of vulnerability. Evolving omics technologies in genomics, epigenomics and mitochondriomics have the potential to generate data that enhance exposure assessment to include the exposome - the totality of the lifetime exposure burden - and provide biology-based estimates of individual risks. Applying omics technologies to expand our knowledge of individual risk and susceptibility will augment biological data in the prediction of variability and response to disease, thereby further advancing EDC research. Together, refined exposure characterization and enhanced disease-risk prediction will help to bridge crucial gaps in EDC research and create opportunities to move the field towards a new vision - precision public health.
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Affiliation(s)
- Carmen Messerlian
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA
| | - Rosie M Martinez
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA; and at the Laboratory of Precision Environmental Biosciences, Department of Environmental Health Sciences, Columbia Mailman School of Public Health, New York, New York 10032, USA
| | - Russ Hauser
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115, USA
| | - Andrea A Baccarelli
- Laboratory of Precision Environmental Biosciences, Department of Environmental Health Sciences, Columbia Mailman School of Public Health, New York, New York 10032, USA
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23
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Mechta M, Ingerslev LR, Fabre O, Picard M, Barrès R. Evidence Suggesting Absence of Mitochondrial DNA Methylation. Front Genet 2017; 8:166. [PMID: 29163634 PMCID: PMC5671948 DOI: 10.3389/fgene.2017.00166] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 10/16/2017] [Indexed: 11/28/2022] Open
Abstract
Methylation of nuclear genes encoding mitochondrial proteins participates in the regulation of mitochondria function. The existence of cytosine methylation in the mitochondrial genome is debated. To investigate whether mitochondrial DNA (mtDNA) is methylated, we used both targeted- and whole mitochondrial genome bisulfite sequencing in cell lines and muscle tissue from mouse and human origin. While unconverted cytosines were detected in some portion of the mitochondrial genome, their abundance was inversely associated to the sequencing depth, indicating that sequencing analysis can bias the estimation of mtDNA methylation levels. In intact mtDNA, few cytosines remained 100% unconverted. However, removal of supercoiled structures of mtDNA with the restriction enzyme BamHI prior to bisulfite sequencing decreased cytosine unconversion rate to <1.5% at all the investigated regions: D-loop, tRNA-F+12S, 16S, ND5 and CYTB, suggesting that mtDNA supercoiled structure blocks the access to bisulfite conversion. Here, we identified an artifact of mtDNA bisulfite sequencing that can lead to an overestimation of mtDNA methylation levels. Our study supports that cytosine methylation is virtually absent in mtDNA.
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Affiliation(s)
- Mie Mechta
- Section of Integrative Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lars R Ingerslev
- Section of Integrative Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Odile Fabre
- Section of Integrative Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Martin Picard
- Department of Psychiatry and Neurology, Division of Behavioral Medicine, Merritt Center, Columbia Translational Neuroscience Initiative, Columbia University Medical Center, New York, NY, United States
| | - Romain Barrès
- Section of Integrative Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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24
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Kang X, Hu L, Shen P, Li R, Liu D. SMRT Sequencing Revealed Mitogenome Characteristics and Mitogenome-Wide DNA Modification Pattern in Ophiocordyceps sinensis. Front Microbiol 2017; 8:1422. [PMID: 28798740 PMCID: PMC5529405 DOI: 10.3389/fmicb.2017.01422] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/13/2017] [Indexed: 11/24/2022] Open
Abstract
Single molecule, real-time (SMRT) sequencing was used to characterize mitochondrial (mt) genome of Ophiocordyceps sinensis and to analyze the mt genome-wide pattern of epigenetic DNA modification. The complete mt genome of O. sinensis, with a size of 157,539 bp, is the fourth largest Ascomycota mt genome sequenced to date. It contained 14 conserved protein-coding genes (PCGs), 1 intronic protein rps3, 27 tRNAs and 2 rRNA subunits, which are common characteristics of the known mt genomes in Hypocreales. A phylogenetic tree inferred from 14 PCGs in Pezizomycotina fungi supports O. sinensis as most closely related to Hirsutella rhossiliensis in Ophiocordycipitaceae. A total of 36 sequence sites in rps3 were under positive selection, with dN/dS >1 in the 20 compared fungi. Among them, 16 sites were statistically significant. In addition, the mt genome-wide base modification pattern of O. sinensis was determined in this study, especially DNA methylation. The methylations were located in coding and uncoding regions of mt PCGs in O. sinensis, and might be closely related to the expression of PCGs or the binding affinity of transcription factor A to mtDNA. Consequently, these methylations may affect the enzymatic activity of oxidative phosphorylation and then the mt respiratory rate; or they may influence mt biogenesis. Therefore, methylations in the mitogenome of O. sinensis might be a genetic feature to adapt to the cold and low PO2 environment at high altitude, where O. sinensis is endemic. This is the first report on epigenetic modifications in a fungal mt genome.
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Affiliation(s)
- Xincong Kang
- Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural UniversityChangsha, China
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
| | - Liqin Hu
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
| | - Pengyuan Shen
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
| | - Rui Li
- Nextomics BiosciencesWuhan, China
| | - Dongbo Liu
- Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural UniversityChangsha, China
- Horticulture and Landscape College, Hunan Agricultural UniversityChangsha, China
- State Key Laboratory of Subhealth Intervention TechnologyChangsha, China
- Hunan Co-Innovation Center for Utilization of Botanical Functional IngredientsChangsha, China
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25
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Saini SK, Mangalhara KC, Prakasam G, Bamezai RNK. DNA Methyltransferase1 (DNMT1) Isoform3 methylates mitochondrial genome and modulates its biology. Sci Rep 2017; 7:1525. [PMID: 28484249 PMCID: PMC5431478 DOI: 10.1038/s41598-017-01743-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 04/12/2017] [Indexed: 12/21/2022] Open
Abstract
Here we demonstrate localization of the isoform3 of DNA Methyltransferase1 (DNMT1) enzyme to mitochondria, instead of isoform1 as reported earlier. The fused DNMT1-isoform1, reported earlier to localize in mitochondria, surprisingly showed its exclusive presence inside the nucleus after its ectopic expression; and failed to localize in mitochondria. On the other hand, ectopically expressed DNMT1-isoform3 targeted itself to mitochondria and subsequently methylated CpG regions in the mitochondrial genome. In addition, overexpression of DNMT1-isoform3 affected mitochondrial biology and regulated its function. Under different conditions of oxidative and nutritional stress, this isoform was down-regulated, resulting in hypomethylation of mitochondrial genome. Our study reveals how DNMT1-isoform3, instead of isoform1, is responsible for mtDNA methylation, influencing its biology.
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Affiliation(s)
- Sunil Kumar Saini
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Kailash Chandra Mangalhara
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Gopinath Prakasam
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - R N K Bamezai
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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Mitochondrial DNA in innate immune responses and inflammatory pathology. Nat Rev Immunol 2017; 17:363-375. [PMID: 28393922 DOI: 10.1038/nri.2017.21] [Citation(s) in RCA: 626] [Impact Index Per Article: 89.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mitochondrial DNA (mtDNA) - which is well known for its role in oxidative phosphorylation and maternally inherited mitochondrial diseases - is increasingly recognized as an agonist of the innate immune system that influences antimicrobial responses and inflammatory pathology. On entering the cytoplasm, extracellular space or circulation, mtDNA can engage multiple pattern-recognition receptors in cell-type- and context-dependent manners to trigger pro-inflammatory and type I interferon responses. Here, we review the expanding research field of mtDNA in innate immune responses to highlight new mechanistic insights and discuss the physiological and pathological relevance of this exciting area of mitochondrial biology.
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Experimental mitochondria-targeted DNA methylation identifies GpC methylation, not CpG methylation, as potential regulator of mitochondrial gene expression. Sci Rep 2017; 7:177. [PMID: 28282966 PMCID: PMC5428053 DOI: 10.1038/s41598-017-00263-z] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 02/14/2017] [Indexed: 11/09/2022] Open
Abstract
Like the nucleus, mitochondria contain their own DNA and recent reports provide accumulating evidence that also the mitochondrial DNA (mtDNA) is subjective to DNA methylation. This evidence includes the demonstration of mitochondria-localised DNA methyltransferases and demethylases, and the detection of mtDNA methylation as well as hydroxymethylation. Importantly, differential mtDNA methylation has been linked to aging and diseases, including cancer and diabetes. However, functionality of mtDNA methylation has not been demonstrated. Therefore, we targeted DNA methylating enzymes (modifying cytosine in the CpG or GpC context) to the mtDNA. Unexpectedly, mtDNA gene expression remained unchanged upon induction of CpG mtDNA methylation, whereas induction of C-methylation in the GpC context decreased mtDNA gene expression. Intriguingly, in the latter case, the three mtDNA promoters were differentially affected in each cell line, while cellular function seemed undisturbed. In conclusion, this is the first study which directly addresses the potential functionality of mtDNA methylation. Giving the important role of mitochondria in health and disease, unravelling the impact of mtDNA methylation adds to our understanding of the role of mitochondria in physiological and pathophysiological processes.
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Matilainen O, Quirós PM, Auwerx J. Mitochondria and Epigenetics - Crosstalk in Homeostasis and Stress. Trends Cell Biol 2017; 27:453-463. [PMID: 28274652 DOI: 10.1016/j.tcb.2017.02.004] [Citation(s) in RCA: 214] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/07/2017] [Accepted: 02/12/2017] [Indexed: 12/22/2022]
Abstract
Through epigenetic mechanisms cells integrate environmental stimuli to fine-tune gene expression levels. Mitochondrial function is essential to provide the intermediate metabolites necessary to generate and modify epigenetic marks in the nucleus, which in turn can regulate the expression of mitochondrial proteins. In this review we summarize the function of mitochondria in the regulation of epigenetic mechanisms as a new aspect of mitonuclear communication. We focus in particular on the most common epigenetic modifications - histone acetylation and histone and DNA methylation. We also discuss the emerging field of mitochondrial DNA (mtDNA) methylation, whose physiological role remains unknown. Finally, we describe the essential role of some histone modifications in regulating the mitochondrial unfolded protein response (UPRmt) and the mitochondrial stress-dependent lifespan extension.
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Affiliation(s)
- Olli Matilainen
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Pedro M Quirós
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Johan Auwerx
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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Massie CE, Mills IG, Lynch AG. The importance of DNA methylation in prostate cancer development. J Steroid Biochem Mol Biol 2017; 166:1-15. [PMID: 27117390 DOI: 10.1016/j.jsbmb.2016.04.009] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 04/09/2016] [Accepted: 04/17/2016] [Indexed: 02/08/2023]
Abstract
After briefly reviewing the nature of DNA methylation, its general role in cancer and the tools available to interrogate it, we consider the literature surrounding DNA methylation as relating to prostate cancer. Specific consideration is given to recurrent alterations. A list of frequently reported genes is synthesized from 17 studies that have reported on methylation changes in malignant prostate tissue, and we chart the timing of those changes in the diseases history through amalgamation of several previously published data sets. We also review associations with genetic alterations and hormone signalling, before the practicalities of investigating prostate cancer methylation using cell lines are assessed. We conclude by outlining the interplay between DNA methylation and prostate cancer metabolism and their regulation by androgen receptor, with a specific discussion of the mitochondria and their associations with DNA methylation.
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Affiliation(s)
- Charles E Massie
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, UK
| | - Ian G Mills
- Prostate Cancer Research Group, Centre for Molecular Medicine (Norway), University of Oslo and Oslo University Hospitals, Gaustadalleen, Oslo, Norway; Department of Molecular Oncology, Oslo University Hospitals, Oslo, Norway; PCUK/Movember Centre of Excellence for Prostate Cancer Research, Centre for Cancer Research and Cell Biology (CCRCB), Queen's University Belfast, Belfast, UK
| | - Andy G Lynch
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, UK.
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Bacalini MG, D'Aquila P, Marasco E, Nardini C, Montesanto A, Franceschi C, Passarino G, Garagnani P, Bellizzi D. The methylation of nuclear and mitochondrial DNA in ageing phenotypes and longevity. Mech Ageing Dev 2017; 165:156-161. [PMID: 28115210 DOI: 10.1016/j.mad.2017.01.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 11/29/2016] [Accepted: 01/16/2017] [Indexed: 12/28/2022]
Abstract
An increasing body of data is progressively indicating that the comprehension of the epigenetic landscape, actively integrated with the genetic elements, is crucial to delineate the molecular basis of the inter-individual complexity of ageing process. Indeed, it has emerged that DNA methylation changes occur during ageing, consisting mainly in a progressive process of genome demethylation, in a hypermethylation of gene-specific CpG dinucleotides, as well as in an inter-individual divergence of the epigenome due to stochastic events and environmental exposures throughout life, namely as epigenetic drift. Additionally, it has also come to light an implication of the mitochondrial genome in the regulation of the intracellular epigenetic landscape, as demonstrated by the being itself object of epigenetic modifications. An overview of DNA methylation changes occurring during ageing process at both nuclear and mitochondrial level will be described in this review, also taking into account the recent and promising data available on the 5-hydroxymethylcytosine.
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Affiliation(s)
- Maria Giulia Bacalini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Via Altura 1/8, 40139 Bologna, Italy
| | - Patrizia D'Aquila
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy
| | - Elena Marasco
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy
| | | | - Alberto Montesanto
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy
| | - Claudio Franceschi
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Via Altura 1/8, 40139 Bologna, Italy
| | - Giuseppe Passarino
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy
| | - Paolo Garagnani
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy; Applied Biomedical Research Center, S.Orsola-Malpighi Polyclinic, 40138 Bologna, Italy; Interdepartmental Center "L. Galvani", Alma Mater Studiorum, University of Bologna, 40126 Bologna, Italy.
| | - Dina Bellizzi
- Department of Biology, Ecology and Earth Sciences, University of Calabria, 87036 Rende, Italy.
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Mitochondrial DNA Methylation and Related Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1038:117-132. [DOI: 10.1007/978-981-10-6674-0_9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Blanch M, Mosquera JL, Ansoleaga B, Ferrer I, Barrachina M. Altered Mitochondrial DNA Methylation Pattern in Alzheimer Disease-Related Pathology and in Parkinson Disease. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:385-97. [PMID: 26776077 DOI: 10.1016/j.ajpath.2015.10.004] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 09/30/2015] [Accepted: 10/13/2015] [Indexed: 12/28/2022]
Abstract
Mitochondrial dysfunction is linked with the etiopathogenesis of Alzheimer disease and Parkinson disease. Mitochondria are intracellular organelles essential for cell viability and are characterized by the presence of the mitochondrial (mt)DNA. DNA methylation is a well-known epigenetic mechanism that regulates nuclear gene transcription. However, mtDNA methylation is not the subject of the same research attention. The present study shows the presence of mitochondrial 5-methylcytosine in CpG and non-CpG sites in the entorhinal cortex and substantia nigra of control human postmortem brains, using the 454 GS FLX Titanium pyrosequencer. Moreover, increased mitochondrial 5-methylcytosine levels are found in the D-loop region of mtDNA in the entorhinal cortex in brain samples with Alzheimer disease-related pathology (stages I to II and stages III to IV of Braak and Braak; n = 8) with respect to control cases. Interestingly, this region shows a dynamic pattern in the content of mitochondrial 5-methylcytosine in amyloid precursor protein/presenilin 1 mice along with Alzheimer disease pathology progression (3, 6, and 12 months of age). Finally, a loss of mitochondrial 5-methylcytosine levels in the D-loop region is found in the substantia nigra in Parkinson disease (n = 10) with respect to control cases. In summary, the present findings suggest mtDNA epigenetic modulation in human brain is vulnerable to neurodegenerative disease states.
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Affiliation(s)
- Marta Blanch
- Institute of Neuropathology, Bellvitge University Hospital (Bellvitge Biomedical Research Institute) IDIBELL, L'Hospitalet de Llobregat, Spain
| | | | - Belén Ansoleaga
- Institute of Neuropathology, Bellvitge University Hospital (Bellvitge Biomedical Research Institute) IDIBELL, L'Hospitalet de Llobregat, Spain
| | - Isidre Ferrer
- Institute of Neuropathology, Bellvitge University Hospital (Bellvitge Biomedical Research Institute) IDIBELL, L'Hospitalet de Llobregat, Spain; Networked Biomedical Research Centre for NeuroDegenerative Disorders (CIBERNED), Madrid, Spain; Departament of Pathology and Experimental Therapeutics, University of Barcelona, L'Hospitalet de Llobregat, Spain
| | - Marta Barrachina
- Institute of Neuropathology, Bellvitge University Hospital (Bellvitge Biomedical Research Institute) IDIBELL, L'Hospitalet de Llobregat, Spain; Networked Biomedical Research Centre for NeuroDegenerative Disorders (CIBERNED), Madrid, Spain.
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CpG methylation patterns of human mitochondrial DNA. Sci Rep 2016; 6:23421. [PMID: 26996456 PMCID: PMC4800444 DOI: 10.1038/srep23421] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 03/07/2016] [Indexed: 12/19/2022] Open
Abstract
The epigenetic modification of mitochondrial DNA (mtDNA) is still in controversy. To clarify this point, we applied the gold standard method for DNA methylation, bisulfite pyrosequencing, to examine human mtDNA methylation status. Before bisulfite conversion, BamHI was used to digest DNA to open the loop of mtDNA. The results demonstrated that the linear mtDNA had significantly higher bisulfite conversion efficiency compared with circular mtDNA. Furthermore, the methylation values obtained from linear mtDNA were significantly lower than that of circular mtDNA, which was verified by SEQUENOM MassARRAY. The above impacts of circular structure were also observed in lung DNA samples but not in saliva DNA samples. Mitochondrial genome methylation of blood samples and saliva samples from 14 unrelated individuals was detected. The detected regions covered 83 CpG sites across mtDNA including D-loop, 12 S rRNA, 16 S rRNA, ND1, COXI, ND3, ND4, ND5, CYTB. We found that the average methylation levels of nine regions were all less than 2% for both sample types. In conclusion, our findings firstly show that the circular structure of mtDNA affects bisulfite conversion efficiency, which leads to overestimation of mtDNA methylation values. CpG methylation in human mtDNA is a very rare event at most DNA regions.
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34
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Devall M, Roubroeks J, Mill J, Weedon M, Lunnon K. Epigenetic regulation of mitochondrial function in neurodegenerative disease: New insights from advances in genomic technologies. Neurosci Lett 2016; 625:47-55. [PMID: 26876477 DOI: 10.1016/j.neulet.2016.02.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 10/22/2022]
Abstract
The field of mitochondrial epigenetics has received increased attention in recent years and changes in mitochondrial DNA (mtDNA) methylation has been implicated in a number of diseases, including neurodegenerative diseases such as amyotrophic lateral sclerosis. However, current publications have been limited by the use of global or targeted methods of measuring DNA methylation. In this review, we discuss current findings in mitochondrial epigenetics as well as its potential role as a regulator of mitochondria within the brain. Finally, we summarize the current technologies best suited to capturing mtDNA methylation, and how a move towards whole epigenome sequencing of mtDNA may help to advance our current understanding of the field.
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Affiliation(s)
- Matthew Devall
- Institute of Clinical and Biomedical Science, University of Exeter Medical School, University of Exeter, Devon, UK
| | - Janou Roubroeks
- Institute of Clinical and Biomedical Science, University of Exeter Medical School, University of Exeter, Devon, UK; Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHENS), Maastricht University, Maastricht, The Netherlands
| | - Jonathan Mill
- Institute of Clinical and Biomedical Science, University of Exeter Medical School, University of Exeter, Devon, UK; Institute of Psychiatry, Psychology & Neuroscience (IoPPN), King's College London, De Crespigny Park, London, UK
| | - Michael Weedon
- Institute of Clinical and Biomedical Science, University of Exeter Medical School, University of Exeter, Devon, UK
| | - Katie Lunnon
- Institute of Clinical and Biomedical Science, University of Exeter Medical School, University of Exeter, Devon, UK.
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35
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Nakahira K, Hisata S, Choi AMK. The Roles of Mitochondrial Damage-Associated Molecular Patterns in Diseases. Antioxid Redox Signal 2015; 23:1329-50. [PMID: 26067258 PMCID: PMC4685486 DOI: 10.1089/ars.2015.6407] [Citation(s) in RCA: 199] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
SIGNIFICANCE Mitochondria, vital cellular power plants to generate energy, are involved in immune responses. Mitochondrial damage-associated molecular patterns (DAMPs) are molecules that are released from mitochondria to extracellular space during cell death and include not only proteins but also DNA or lipids. Mitochondrial DAMPs induce inflammatory responses and are critically involved in the pathogenesis of various diseases. RECENT ADVANCES Recent studies elucidate the molecular mechanisms by which mitochondrial DAMPs are released and initiate immune responses by use of genetically modulated cells or animals. Importantly, the levels of mitochondrial DAMPs in patients are often associated with severity and prognosis of human diseases, such as infection, asthma, ischemic heart disease, and cancer. CRITICAL ISSUES Although mitochondrial DAMPs can represent proinflammatory molecules in various experimental models, their roles in human diseases may be multifunctional and complex. It remains unclear where and how mitochondrial DAMPs are liberated into extracellular spaces and exert their biological functions particularly in vivo. In addition, while mitochondria can secrete several types of DAMPs during cell death, the interaction of each mitochondrial DAMP (e.g., synergistic effects) remains unclear. FUTURE DIRECTIONS Regulation of mitochondrial DAMP-mediated immune responses may be important to alter the progression of human diseases. In addition, measuring mitochondrial DAMPs in patients may be clinically useful as biomarkers to predict prognosis or response to therapies. Further studies of the mechanisms by which mitochondrial DAMPs impact the initiation and progression of diseases may lead to the development of therapeutics specifically targeting this pathway. Antioxid.
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Affiliation(s)
- Kiichi Nakahira
- 1 Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College and New York-Presbyterian Hospital , New York, New York.,2 Division of Pulmonary and Critical Care Medicine, Weill Cornell Medical College , New York, New York
| | - Shu Hisata
- 1 Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College and New York-Presbyterian Hospital , New York, New York.,2 Division of Pulmonary and Critical Care Medicine, Weill Cornell Medical College , New York, New York
| | - Augustine M K Choi
- 1 Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College and New York-Presbyterian Hospital , New York, New York.,2 Division of Pulmonary and Critical Care Medicine, Weill Cornell Medical College , New York, New York
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36
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Li J, Li R, Wang Y, Hu X, Zhao Y, Li L, Feng C, Gu X, Liang F, Lamont SJ, Hu S, Zhou H, Li N. Genome-wide DNA methylome variation in two genetically distinct chicken lines using MethylC-seq. BMC Genomics 2015; 16:851. [PMID: 26497311 PMCID: PMC4619007 DOI: 10.1186/s12864-015-2098-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 10/15/2015] [Indexed: 12/30/2022] Open
Abstract
Background DNA cytosine methylation is an important epigenetic modification that has significant effects on a variety of biological processes in animals. Avian species hold a crucial position in evolutionary history. In this study, we used whole-genome bisulfite sequencing (MethylC-seq) to generate single base methylation profiles of lungs in two genetically distinct and highly inbred chicken lines (Fayoumi and Leghorn) that differ in genetic resistance to multiple pathogens, and we explored the potential regulatory role of DNA methylation associated with immune response differences between the two chicken lines. Methods The MethylC-seq was used to generate single base DNA methylation profiles of Fayoumi and Leghorn birds. In addition, transcriptome profiling using RNA–seq from the same chickens and tissues were obtained to interrogate how DNA methylation regulates gene transcription on a genome-wide scale. Results The general DNA methylation pattern across different regions of genes was conserved compared to other species except for hyper-methylation of repeat elements, which was not observed in chicken. The methylation level of miRNA and pseudogene promoters was high, which indicates that silencing of these genes may be partially due to promoter hyper-methylation. Interestingly, the promoter regions of more recently evolved genes tended to be more highly methylated, whereas the gene body regions of evolutionarily conserved genes were more highly methylated than those of more recently evolved genes. Immune-related GO (Gene Ontology) terms were significantly enriched from genes within the differentially methylated regions (DMR) between Fayoumi and Leghorn, which implicates DNA methylation as one of the regulatory mechanisms modulating immune response differences between these lines. Conclusions This study establishes a single-base resolution DNA methylation profile of chicken lung and suggests a regulatory role of DNA methylation in controlling gene expression and maintaining genome transcription stability. Furthermore, profiling the DNA methylomes of two genetic lines that differ in disease resistance provides a unique opportunity to investigate the potential role of DNA methylation in host disease resistance. Our study provides a foundation for future studies on epigenetic modulation of host immune response to pathogens in chickens. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2098-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jinxiu Li
- The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing, 100193, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Rujiao Li
- Core Genomic Facility, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Ying Wang
- Department of Animal Science, University of California, Davis, CA, 95616, USA
| | - Xiaoxiang Hu
- The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing, 100193, China
| | - Yiqiang Zhao
- The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing, 100193, China
| | - Li Li
- The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing, 100193, China
| | - Chungang Feng
- The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing, 100193, China
| | - Xiaorong Gu
- The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing, 100193, China
| | - Fang Liang
- Core Genomic Facility, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Susan J Lamont
- Department of Animal Science, Iowa State University, Ames, IA, 50011, USA
| | - Songnian Hu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Huaijun Zhou
- Department of Animal Science, University of California, Davis, CA, 95616, USA. .,Department of Poultry Science, Texas A&M University, College Station, TX, 77845, USA.
| | - Ning Li
- The State Key Laboratory for Agro-biotechnology, China Agricultural University, Beijing, 100193, China. .,National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, 100193, China. .,College of Animal Science and Technology, Yunnan Agricultural University, Kunming, Yunnan, China.
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Ghosh S, Singh KK, Sengupta S, Scaria V. Mitoepigenetics: The different shades of grey. Mitochondrion 2015; 25:60-6. [PMID: 26437363 DOI: 10.1016/j.mito.2015.09.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 09/28/2015] [Indexed: 11/24/2022]
Abstract
Epigenetic modifications of the nuclear genome have been well studied and it is established that these modifications play a key role in nuclear gene expression. However, the status of mitochondrial epigenetic modifications has not been delved in detail. The recent technological advancements in the genome analyzing tools and techniques, have helped in investigating mitochondrial epigenetic modifications with greater resolution and studies have indicated a regulatory role of the mitochondrial epigenome. Association of mitochondrial DNA methylation with various disease conditions, drug treatment, aging, exposure to environmental pollutants etc. has lent credence to this belief. Herein, we have reviewed studies on mitochondrial epigenetic modifications with a focus to comprehend its regulatory role in gene expression and disease association.
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Affiliation(s)
- Sourav Ghosh
- Genomics and Molecular Medicine, CSIR Institute of Genomics and Integrative Biology (CSIR IGIB), Mathura Road, Delhi, 110 020 Delhi, India; Academy of Scientific and Innovative Research (AcSIR), CSIR IGIB South Campus, Mathura Road, Delhi, 110020 Delhi, India
| | - Keshav K Singh
- Departments of Genetics, Pathology, Environmental Health, University of Alabama at Birmingham, Birmingham, Alabama; Center for Free Radical Biology, Center for Aging and UAB Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama; Birmingham Veterans Affairs Medical Center, Birmingham, AL, USA 35294
| | - Shantanu Sengupta
- Genomics and Molecular Medicine, CSIR Institute of Genomics and Integrative Biology (CSIR IGIB), Mathura Road, Delhi, 110 020 Delhi, India; Academy of Scientific and Innovative Research (AcSIR), CSIR IGIB South Campus, Mathura Road, Delhi, 110020 Delhi, India
| | - Vinod Scaria
- GN Ramachandran Knowledge Center for Genome Informatics, CSIR Institute of Genomics and Integrative Biology (CSIR IGIB), Mathura Road, Delhi, 110 020 Delhi, India; Academy of Scientific and Innovative Research (AcSIR), CSIR IGIB South Campus, Mathura Road, Delhi, 110020 Delhi, India.
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Devall M, Mill J, Lunnon K. The mitochondrial epigenome: a role in Alzheimer's disease? Epigenomics 2015; 6:665-75. [PMID: 25531259 DOI: 10.2217/epi.14.50] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Considerable evidence suggests that mitochondrial dysfunction occurs early in Alzheimer's disease, both in affected brain regions and in leukocytes, potentially precipitating neurodegeneration through increased oxidative stress. Epigenetic processes are emerging as a dynamic mechanism through which environmental signals may contribute to cellular changes, leading to neuropathology and disease. Until recently, little attention was given to the mitochondrial epigenome itself, as preliminary studies indicated an absence of DNA modifications. However, recent research has demonstrated that epigenetic changes to the mitochondrial genome do occur, potentially playing an important role in several disorders characterized by mitochondrial dysfunction. This review explores the potential role of mitochondrial epigenetic dysfunction in Alzheimer's disease etiology and discusses some technical issues pertinent to the study of these processes.
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Affiliation(s)
- Matthew Devall
- University of Exeter Medical School, RILD Level 4, Barrack Road, Exeter, Devon, UK
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Castegna A, Iacobazzi V, Infantino V. The mitochondrial side of epigenetics. Physiol Genomics 2015; 47:299-307. [PMID: 26038395 DOI: 10.1152/physiolgenomics.00096.2014] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 05/26/2015] [Indexed: 12/31/2022] Open
Abstract
The bidirectional cross talk between nuclear and mitochondrial DNA is essential for cellular homeostasis and proper functioning. Mitochondria depend on nuclear contribution for much of their functionality, but their activities have been recently recognized to control nuclear gene expression as well as cell function in many different ways. Epigenetic mechanisms, which tune gene expression in response to environmental stimuli, are key regulatory events at the interplay between mitochondrial and nuclear interactions. Emerging findings indicate that epigenetic factors can be targets or instruments of mitochondrial-nuclear cross talk. Additionally, the growing interest into mtDNA epigenetic modifications opens new avenues into the interaction mechanisms between mitochondria and nucleus. In this review we summarize the points of mitochondrial and nuclear reciprocal control involving epigenetic factors, focusing on the role of mitochondrial genome and metabolism in shaping epigenetic modulation of gene expression. The relevance of the new findings on the methylation of mtDNA is also highlighted as a new frontier in the complex scenario of mitochondrial-nuclear communication.
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Affiliation(s)
- Alessandra Castegna
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro," Bari, Italy; Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro," Bari, Italy;
| | - Vito Iacobazzi
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari "Aldo Moro," Bari, Italy; Center of Excellence in Comparative Genomics, University of Bari "Aldo Moro," Bari, Italy; CNR Institute of Biomembranes and Bioenergetics, Bari, Italy; and
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Maresca A, Zaffagnini M, Caporali L, Carelli V, Zanna C. DNA methyltransferase 1 mutations and mitochondrial pathology: is mtDNA methylated? Front Genet 2015; 6:90. [PMID: 25815005 PMCID: PMC4357308 DOI: 10.3389/fgene.2015.00090] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 02/19/2015] [Indexed: 01/31/2023] Open
Abstract
Autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN) and Hereditary sensory neuropathy with dementia and hearing loss (HSN1E) are two rare, overlapping neurodegenerative syndromes that have been recently linked to allelic dominant pathogenic mutations in the DNMT1 gene, coding for DNA (cytosine-5)-methyltransferase 1 (DNMT1). DNMT1 is the enzyme responsible for maintaining the nuclear genome methylation patterns during the DNA replication and repair, thus regulating gene expression. The mutations responsible for ADCA-DN and HSN1E affect the replication foci targeting sequence domain, which regulates DNMT1 binding to chromatin. DNMT1 dysfunction is anticipated to lead to a global alteration of the DNA methylation pattern with predictable downstream consequences on gene expression. Interestingly, ADCA-DN and HSN1E phenotypes share some clinical features typical of mitochondrial diseases, such as optic atrophy, peripheral neuropathy, and deafness, and some biochemical evidence of mitochondrial dysfunction. The recent discovery of a mitochondrial isoform of DNMT1 and its proposed role in methylating mitochondrial DNA (mtDNA) suggests that DNMT1 mutations may directly affect mtDNA and mitochondrial physiology. On the basis of this latter finding the link between DNMT1 abnormal activity and mitochondrial dysfunction in ADCA-DN and HSN1E appears intuitive, however, mtDNA methylation remains highly debated. In the last years several groups demonstrated the presence of 5-methylcytosine in mtDNA by different approaches, but, on the other end, the opposite evidence that mtDNA is not methylated has also been published. Since over 1500 mitochondrial proteins are encoded by the nuclear genome, the altered methylation of these genes may well have a critical role in leading to the mitochondrial impairment observed in ADCA-DN and HSN1E. Thus, many open questions still remain unanswered, such as why mtDNA should be methylated, and how this process is regulated and executed?
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Affiliation(s)
- Alessandra Maresca
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences, University of Bologna Bologna, Italy
| | - Mirko Zaffagnini
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences, University of Bologna Bologna, Italy
| | - Leonardo Caporali
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences, University of Bologna Bologna, Italy
| | - Valerio Carelli
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences, University of Bologna Bologna, Italy
| | - Claudia Zanna
- Unit of Neurology, Department of Biomedical and NeuroMotor Sciences, University of Bologna Bologna, Italy
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41
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Mitochondria in health, aging and diseases: the epigenetic perspective. Biogerontology 2015; 16:569-85. [DOI: 10.1007/s10522-015-9562-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 02/19/2015] [Indexed: 01/15/2023]
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Chen GG, Diallo AB, Poujol R, Nagy C, Staffa A, Vaillancourt K, Lutz PE, Ota VK, Mash DC, Turecki G, Ernst C. BisQC: an operational pipeline for multiplexed bisulfite sequencing. BMC Genomics 2014; 15:290. [PMID: 24734894 PMCID: PMC4234473 DOI: 10.1186/1471-2164-15-290] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 04/08/2014] [Indexed: 11/24/2022] Open
Abstract
Background Bisulfite sequencing is the most efficient single nucleotide resolution method for analysis of methylation status at whole genome scale, but improved quality control metrics are needed to better standardize experiments. Results We describe BisQC, a step-by-step method for multiplexed bisulfite-converted DNA library construction, pooling, spike-in content, and bioinformatics. We demonstrate technical improvements for library preparation and bioinformatic analyses that can be done in standard laboratories. We find that decoupling amplification of bisulfite converted (bis) DNA from the indexing reaction is an advantage, specifically in reducing total PCR cycle number and pre-selecting high quality bis-libraries. We also introduce a progressive PCR method for optimal library amplification and size-selection. At the sequencing stage, we thoroughly test the benefits of pooling non-bis DNA library with bis-libraries and find that BisSeq libraries can be pooled with a high proportion of non-bis DNA libraries with minimal impact on BisSeq output. For informatics analysis, we propose a series of optimization steps including the utilization of the mitochondrial genome as a QC standard, and we assess the validity of using duplicate reads for coverage statistics. Conclusion We demonstrate several quality control checkpoints at the library preparation, pre-sequencing, post-sequencing, and post-alignment stages, which should prove useful in determining sample and processing quality. We also determine that including a significant portion of non-bisulfite converted DNA with bisulfite converted DNA has a minimal impact on usable bisulfite read output.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Carl Ernst
- Department of Psychiatry, McGill University, Douglas Hospital Research Institute, Montreal, Quebec, Canada.
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Bellizzi D, D'Aquila P, Scafone T, Giordano M, Riso V, Riccio A, Passarino G. The control region of mitochondrial DNA shows an unusual CpG and non-CpG methylation pattern. DNA Res 2013; 20:537-47. [PMID: 23804556 PMCID: PMC3859322 DOI: 10.1093/dnares/dst029] [Citation(s) in RCA: 195] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 05/30/2013] [Indexed: 11/23/2022] Open
Abstract
DNA methylation is a common epigenetic modification of the mammalian genome. Conflicting data regarding the possible presence of methylated cytosines within mitochondrial DNA (mtDNA) have been reported. To clarify this point, we analysed the methylation status of mtDNA control region (D-loop) on human and murine DNA samples from blood and cultured cells by bisulphite sequencing and methylated/hydroxymethylated DNA immunoprecipitation assays. We found methylated and hydroxymethylated cytosines in the L-strand of all samples analysed. MtDNA methylation particularly occurs within non-C-phosphate-G (non-CpG) nucleotides, mainly in the promoter region of the heavy strand and in conserved sequence blocks, suggesting its involvement in regulating mtDNA replication and/or transcription. We observed DNA methyltransferases within the mitochondria, but the inactivation of Dnmt1, Dnmt3a, and Dnmt3b in mouse embryonic stem (ES) cells results in a reduction of the CpG methylation, while the non-CpG methylation shows to be not affected. This suggests that D-loop epigenetic modification is only partially established by these enzymes. Our data show that DNA methylation occurs in the mtDNA control region of mammals, not only at symmetrical CpG dinucleotides, typical of nuclear genome, but in a peculiar non-CpG pattern previously reported for plants and fungi. The molecular mechanisms responsible for this pattern remain an open question.
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Affiliation(s)
- Dina Bellizzi
- Department of Cell Biology, University of Calabria, Rende 87036, Italy
| | - Patrizia D'Aquila
- Department of Cell Biology, University of Calabria, Rende 87036, Italy
| | - Teresa Scafone
- Department of Cell Biology, University of Calabria, Rende 87036, Italy
| | - Marco Giordano
- Department of Cell Biology, University of Calabria, Rende 87036, Italy
| | - Vincenzo Riso
- Institute of Genetics and Biophysics—Adriano Buzzati Traverso, Napoli 80131, Italy
| | - Andrea Riccio
- Institute of Genetics and Biophysics—Adriano Buzzati Traverso, Napoli 80131, Italy
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Feehery GR, Yigit E, Oyola SO, Langhorst BW, Schmidt VT, Stewart FJ, Dimalanta ET, Amaral-Zettler LA, Davis T, Quail MA, Pradhan S. A method for selectively enriching microbial DNA from contaminating vertebrate host DNA. PLoS One 2013; 8:e76096. [PMID: 24204593 PMCID: PMC3810253 DOI: 10.1371/journal.pone.0076096] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 08/20/2013] [Indexed: 12/05/2022] Open
Abstract
DNA samples derived from vertebrate skin, bodily cavities and body fluids contain both host and microbial DNA; the latter often present as a minor component. Consequently, DNA sequencing of a microbiome sample frequently yields reads originating from the microbe(s) of interest, but with a vast excess of host genome-derived reads. In this study, we used a methyl-CpG binding domain (MBD) to separate methylated host DNA from microbial DNA based on differences in CpG methylation density. MBD fused to the Fc region of a human antibody (MBD-Fc) binds strongly to protein A paramagnetic beads, forming an effective one-step enrichment complex that was used to remove human or fish host DNA from bacterial and protistan DNA for subsequent sequencing and analysis. We report enrichment of DNA samples from human saliva, human blood, a mock malaria-infected blood sample and a black molly fish. When reads were mapped to reference genomes, sequence reads aligning to host genomes decreased 50-fold, while bacterial and Plasmodium DNA sequences reads increased 8-11.5-fold. The Shannon-Wiener diversity index was calculated for 149 bacterial species in saliva before and after enrichment. Unenriched saliva had an index of 4.72, while the enriched sample had an index of 4.80. The similarity of these indices demonstrates that bacterial species diversity and relative phylotype abundance remain conserved in enriched samples. Enrichment using the MBD-Fc method holds promise for targeted microbiome sequence analysis across a broad range of sample types.
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Affiliation(s)
- George R. Feehery
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
| | - Erbay Yigit
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
| | | | | | - Victor T. Schmidt
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America
| | - Fiona J. Stewart
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
| | | | - Linda A. Amaral-Zettler
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America
- Department of Geological Sciences, Brown University, Providence, Rhode Island, United States of America
| | - Theodore Davis
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
| | | | - Sriharsa Pradhan
- New England Biolabs Inc., Ipswich, Massachusetts, United States of America
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Iacobazzi V, Castegna A, Infantino V, Andria G. Mitochondrial DNA methylation as a next-generation biomarker and diagnostic tool. Mol Genet Metab 2013; 110:25-34. [PMID: 23920043 DOI: 10.1016/j.ymgme.2013.07.012] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/12/2013] [Accepted: 07/12/2013] [Indexed: 10/26/2022]
Abstract
Recent expansion of our knowledge on epigenetic changes strongly suggests that not only nuclear DNA (nDNA), but also mitochondrial DNA (mtDNA) may be subjected to epigenetic modifications related to disease development, environmental exposure, drug treatment and aging. Thus, mtDNA methylation is attracting increasing attention as a potential biomarker for the detection and diagnosis of diseases and the understanding of cellular behavior in particular conditions. In this paper we review the current advances in mtDNA methylation studies with particular attention to the evidences of mtDNA methylation changes in diseases and physiological conditions so far investigated. Technological advances for the analysis of epigenetic variations are promising tools to provide insights into methylation of mtDNA with similar resolution levels as those reached for nDNA. However, many aspects related to mtDNA methylation are still unclear. More studies are needed to understand whether and how changes in mtDNA methylation patterns, global and gene specific, are associated to diseases or risk factors.
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Affiliation(s)
- Vito Iacobazzi
- Department of Biosciences, Biotechnology and Pharmacological Sciences, University of Bari, via Orabona 4, 70125 Bari, Italy.
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Kelly RDW, Sumer H, McKenzie M, Facucho-Oliveira J, Trounce IA, Verma PJ, St John JC. The effects of nuclear reprogramming on mitochondrial DNA replication. Stem Cell Rev Rep 2013; 9:1-15. [PMID: 21994000 DOI: 10.1007/s12015-011-9318-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Undifferentiated mouse embryonic stem cells (ESCs) possess low numbers of mitochondrial DNA (mtDNA), which encodes key subunits associated with the generation of ATP through oxidative phosphorylation (OXPHOS). As ESCs differentiate, mtDNA copy number is regulated by the nuclear-encoded mtDNA replication factors, which initiate a major replication event on Day 6 of differentiation. Here, we examined mtDNA replication events in somatic cells reprogrammed to pluripotency, namely somatic cell-ES (SC-ES), somatic cell nuclear transfer ES (NT-ES) and induced pluripotent stem (iPS) cells, all at low-passage. MtDNA copy number in undifferentiated iPS cells was similar to ESCs whilst SC-ES and NT-ES cells had significantly increased levels, which correlated positively and negatively with Nanog and Sox2 expression, respectively. During pluripotency and differentiation, the expression of the mtDNA-specific replication factors, PolgA and Peo1, were differentially expressed in iPS and SC-ES cells when compared to ESCs. Throughout differentiation, reprogrammed somatic cells were unable to accumulate mtDNA copy number, characteristic of ESCs, especially on Day 6. In addition, iPS and SC-ES cells were also unable to regulate ATP content in a manner similar to differentiating ESCs prior to Day 14. The treatment of reprogrammed somatic cells with an inhibitor of de novo DNA methylation, 5-Azacytidine, prior to differentiation enabled iPS cells, but not SC-ES and NT-ES cells, to accumulate mtDNA copies per cell in a manner similar to ESCs. These data demonstrate that the reprogramming process disrupts the regulation of mtDNA replication during pluripotency but this can be re-established through the use of epigenetic modifiers.
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Affiliation(s)
- Richard D W Kelly
- Centre for Reproduction and Development, Monash Institute of Medical Research, Monash University, 27-31 Wright Street, Clayton, Victoria, 3168, Australia
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Byun HM, Panni T, Motta V, Hou L, Nordio F, Apostoli P, Bertazzi PA, Baccarelli AA. Effects of airborne pollutants on mitochondrial DNA methylation. Part Fibre Toxicol 2013; 10:18. [PMID: 23656717 PMCID: PMC3660297 DOI: 10.1186/1743-8977-10-18] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 05/01/2013] [Indexed: 11/23/2022] Open
Abstract
Background Mitochondria have small mitochondrial DNA (mtDNA) molecules independent from the nuclear DNA, a separate epigenetic machinery that generates mtDNA methylation, and are primary sources of oxidative-stress generation in response to exogenous environments. However, no study has yet investigated whether mitochondrial DNA methylation is sensitive to pro-oxidant environmental exposures. Methods We sampled 40 male participants (20 high-, 20 low-exposure) from each of three studies on airborne pollutants, including investigations of steel workers exposed to metal-rich particulate matter (measured as PM1) in Brescia, Italy (Study 1); gas-station attendants exposed to air benzene in Milan, Italy (Study 2); and truck drivers exposed to traffic-derived Elemental Carbon (EC) in Beijing, China (Study 3). We have measured DNA methylation from buffy coats of the participants. We measured methylation by bisulfite-Pyrosequencing in three mtDNA regions, i.e., the transfer RNA phenylalanine (MT-TF), 12S ribosomal RNA (MT-RNR1) gene and “D-loop” control region. All analyses were adjusted for age and smoking. Results In Study 1, participants with high metal-rich PM1 exposure showed higher MT-TF and MT-RNR1 methylation than low-exposed controls (difference = 1.41, P = 0.002); MT-TF and MT-RNR1 methylation was significantly associated with PM1 exposure (beta = 1.35, P = 0.025); and MT-RNR1 methylation was positively correlated with mtDNA copy number (r = 0.36; P = 0.02). D-loop methylation was not associated with PM1 exposure. We found no effects on mtDNA methylation from air benzene (Study 2) and traffic-derived EC exposure (Study 3). Conclusions Mitochondrial MT-TF and MT-RNR1 DNA methylation was associated with metal-rich PM1 exposure and mtDNA copy number. Our results suggest that locus-specific mtDNA methylation is correlated to selected exposures and mtDNA damage. Larger studies are needed to validate our observations.
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Affiliation(s)
- Hyang-Min Byun
- Laboratory of Environmental Epigenetics, Exposure Epidemiology and Risk Program, Harvard School of Public Health, Boston, MA 02115, USA.
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Abstract
Neuroepigenetics, which includes nuclear DNA modifications such as 5-methylcytosine and 5-hydoxymethylcytosine and modifications of nuclear proteins such as histones, is emerging as the leading field in molecular neuroscience. Historically, a functional role for epigenetic mechanisms, including in neuroepigenetics, has been sought in the area of the regulation of nuclear transcription. However, one important compartment of mammalian cell DNA, different from nuclear but equally important for physiological and pathological processes (including in the brain), mitochondrial DNA has for the most part not had a systematic epigenetic characterization. The importance of mitochondria and mitochondrial DNA (particularly its mutations) in central nervous system physiology and pathology has long been recognized. Only recently have mechanisms of mitochondrial DNA methylation and hydroxymethylation, including the discovery of mitochondrial DNA-methyltransferases and the presence and the functionality of 5-methylcytosine and 5-hydroxymethylcytosine in mitochondrial DNA (e.g., in modifying the transcription of mitochondrial genome), been unequivocally recognized as a part of mammalian mitochondrial physiology. Here we summarize for the first time evidence supporting the existence of these mechanisms and we propose the term "mitochondrial epigenetics" to be used when referring to them. Currently, neuroepigenetics does not include mitochondrial epigenetics - a gap that we expect to close in the near future.
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Affiliation(s)
- Hari Manev
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL 60612, USA
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Chinnery PF, Elliott HR, Hudson G, Samuels DC, Relton CL. Epigenetics, epidemiology and mitochondrial DNA diseases. Int J Epidemiol 2012; 41:177-87. [PMID: 22287136 DOI: 10.1093/ije/dyr232] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Over the last two decades, the mutation of mitochondrial DNA (mtDNA) has emerged as a major cause of inherited human disease. The disorders present clinically in at least 1 in 10,000 adults, but pathogenic mutations are found in approximately 1 in 200 of the background population. Mitochondrial DNA is maternally inherited and there can be marked phenotypic variability within the same family. Heteroplasmy is a significant factor and environmental toxins also appear to modulate the phenotype. Although genetic and biochemical studies have provided part of the explanation, a comprehensive understanding of the incomplete penetrance of these diseases is lacking--both at the population and family levels. Here, we review the potential role of epigenetic factors in the pathogenesis of mtDNA diseases and the contribution that epidemiological approaches can make to improve our understanding in this area. Despite being previously dismissed, there is an emerging evidence that mitochondria contain the machinery required to epigenetically modify mtDNA expression. In addition, the increased production of reactive oxygen species seen in several mtDNA diseases could lead to the epigenetic modification of the nuclear genome, including chromatin remodelling and alterations to DNA methylation and microRNA expression, thus contributing to the diverse pathophysiology observed in this group of diseases. These observations open the door to future studies investigating the role of mtDNA methylation in human disease.
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Affiliation(s)
- Patrick F Chinnery
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK.
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DNA methyltransferase 1, cytosine methylation, and cytosine hydroxymethylation in mammalian mitochondria. Proc Natl Acad Sci U S A 2011; 108:3630-5. [PMID: 21321201 DOI: 10.1073/pnas.1012311108] [Citation(s) in RCA: 393] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Mitochondrial DNA (mtDNA) has been reported to contain 5-methylcytosine (5mC) at CpG dinucleotides, as in the nuclear genome, but neither the mechanism generating mtDNA methylation nor its functional significance is known. We now report the presence of 5-hydroxymethylcytosine (5hmC) as well as 5mC in mammalian mtDNA, suggesting that previous studies underestimated the level of cytosine modification in this genome. DNA methyltransferase 1 (DNMT1) translocates to the mitochondria, driven by a mitochondrial targeting sequence located immediately upstream of the commonly accepted translational start site. This targeting sequence is conserved across mammals, and the encoded peptide directs a heterologous protein to the mitochondria. DNMT1 is the only member of the three known catalytically active DNA methyltransferases targeted to the mitochondrion. Mitochondrial DNMT1 (mtDNMT1) binds to mtDNA, proving the presence of mtDNMT1 in the mitochondrial matrix. mtDNMT1 expression is up-regulated by NRF1 and PGC1α, transcription factors that activate expression of nuclear-encoded mitochondrial genes in response to hypoxia, and by loss of p53, a tumor suppressor known to regulate mitochondrial metabolism. Altered mtDNMT1 expression asymmetrically affects expression of transcripts from the heavy and light strands of mtDNA. Hence, mtDNMT1 appears to be responsible for mtDNA cytosine methylation, from which 5hmC is presumed to be derived, and its expression is controlled by factors that regulate mitochondrial function.
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