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Epigenetic Clock: DNA Methylation in Aging. Stem Cells Int 2020; 2020:1047896. [PMID: 32724310 PMCID: PMC7366189 DOI: 10.1155/2020/1047896] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 06/11/2020] [Accepted: 06/20/2020] [Indexed: 02/07/2023] Open
Abstract
Aging, which is accompanied by decreased organ function and increased disease incidence, limits human lifespan and has attracted investigators for thousands of years. In recent decades, with the rapid development of biology, scientists have shown that epigenetic modifications, especially DNA methylation, are key regulators involved in this process. Regular fluctuations in global DNA methylation levels have been shown to accurately estimate biological age and disease prognosis. In this review, we discuss recent findings regarding the relationship between variations in DNA methylation level patterns and aging. In addition, we introduce the known mechanisms by which DNA methylation regulators affect aging and related diseases. As more studies uncover the mechanisms by which DNA methylation regulates aging, antiaging interventions and treatments for related diseases may be developed that enable human life extension.
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Martínez-Iglesias O, Carrera I, Carril JC, Fernández-Novoa L, Cacabelos N, Cacabelos R. DNA Methylation in Neurodegenerative and Cerebrovascular Disorders. Int J Mol Sci 2020; 21:ijms21062220. [PMID: 32210102 PMCID: PMC7139499 DOI: 10.3390/ijms21062220] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/18/2020] [Accepted: 03/18/2020] [Indexed: 02/08/2023] Open
Abstract
DNA methylation is an epigenetic mechanism by which methyl groups are added to DNA, playing a crucial role in gene expression regulation. The aim of the present study is to compare methylation status of healthy subjects with that of patients with Alzheimer’s, Parkinson’s or Cerebrovascular diseases. We also analyze methylation status of a transgenic Alzheimer’s disease mouse model (3xTg-AD). Our results show that both global methylation (n = 141) and hydroxymethylation (n = 131) levels are reduced in DNA samples from buffy coats of patients with neurodegenerative disorders and age-related cerebrovascular disease. The importance of methylation and hydroxymethylation reduction is stressed by the finding that DNMT3a mRNA levels are also downregulated in buffy coats of patients with Dementia (n = 25). Global methylation is also reduced in brain, liver and serum samples of 3xTg-AD vs. wild type mice, such as DNMT3a mRNA levels that are also decreased in the brain of 3xTg-AD (n = 10). These results suggest that the use of global methylation and hydroxymethylation levels, together with the study of DNMT3a expression, could be useful as a new diagnostic biomarker for these prevalent disorders.
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The role of DNA methylation and hydroxymethylation in immunosenescence. Ageing Res Rev 2019; 51:11-23. [PMID: 30769150 DOI: 10.1016/j.arr.2019.01.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 12/12/2022]
Abstract
A healthy functioning immune system is critical to stave off infectious diseases, but as humans and other organisms age, their immune systems decline. As a result, diseases that were readily thwarted in early life pose nontrivial harm and can even be deadly in late life. Immunosenescence is defined as the general deterioration of the immune system with age, and it is characterized by functional changes in hematopoietic stem cells (HSCs) and specific blood cell types as well as changes in levels of numerous factors, particularly those involved in inflammation. Potential mechanisms underlying immunosenescence include epigenetic changes such as changes in DNA methylation (DNAm) and DNA hydroxymethylation (DNAhm) that occur with age. The purpose of this review is to describe what is currently known about the relationship between immunosenescence and the age-related changes to DNAm and DNAhm, and to discuss experimental approaches best suited to fill gaps in our understanding.
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Transcriptional regulators of redox balance and other homeostatic processes with the potential to alter neurodegenerative disease trajectory. Biochem Soc Trans 2017; 45:1295-1303. [PMID: 29150527 PMCID: PMC5730942 DOI: 10.1042/bst20170013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 10/09/2017] [Accepted: 10/11/2017] [Indexed: 02/07/2023]
Abstract
Diverse neurodegenerative diseases share some common aspects to their pathology, with many showing evidence of disruption to the brain's numerous homeostatic processes. As such, imbalanced inflammatory status, glutamate dyshomeostasis, hypometabolism and oxidative stress are implicated in many disorders. That these pathological processes can influence each other both up- and downstream makes for a complicated picture, but means that successfully targeting one area may have an effect on others. This targeting requires an understanding of the mechanisms by which homeostasis is maintained during health, in order to uncover strategies to boost homeostasis in disease. A case in point is redox homeostasis, maintained by antioxidant defences co-ordinately regulated by the transcription factor Nrf2, and capable of preventing not only oxidative stress but also inflammation and neuronal loss in neurodegenerative disease models. The emergence of other master regulators of homeostatic processes in the brain controlling inflammation, mitochondrial biogenesis, glutamate uptake and energy metabolism raises the question as to whether they too can be targeted to alter disease trajectory.
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Miao Z, Xin N, Wei B, Hua X, Zhang G, Leng C, Zhao C, Wu D, Li J, Ge W, Sun M, Xu X. 5-hydroxymethylcytosine is detected in RNA from mouse brain tissues. Brain Res 2016; 1642:546-552. [PMID: 27117867 DOI: 10.1016/j.brainres.2016.04.055] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 04/10/2016] [Accepted: 04/22/2016] [Indexed: 01/05/2023]
Abstract
5-hydroxymethylcytosine (5hmC) is considered as a novel DNA modification and plays an important role in cancer, stem cells, and developmental diseases. In this study, we demonstrated the existence of RNA 5hmC modification in mouse brain RNA by using a dot blot analysis method. Our data indicated that 5hmC modification in RNA samples was less than that in DNA samples. Further, we optimized the conditions for 5hmC detection in RNA samples such as DNase treatment, denature reagents, denature time, sample air-dry time, and the cross-linking time between RNA and membrane. Our results demonstrated that DNase treatment and denature reagents were two important factors that affected the 5hmC detection in RNA samples. By using the optimal conditions for RNA 5hmC detection, we found that the brainstem, the hippocampus, and the cerebellum had high levels of 5hmC modification and 5mC modification in RNA. Finally, we found that RNA 5hmC modification decreased in MPTP-induced Parkinson's disease model in mice. These suggest that 5hmC modification in RNA might play an important regulative role on protein or microRNA expression in these brain tissues. Because DNA 5hmC modification plays an important role in neural differentiation and development as well as neurological diseases, the significance of 5hmC modification in RNA in different neurological diseases needs further investigation. In summary, our study demonstrated for the first time the abundance of 5hmC modification in brain RNA by using a dot blot analysis method and proved that dot blot analysis is a useful method for 5hmC detection in RNA samples.
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Affiliation(s)
- Zhigang Miao
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China; Institute of Neuroscience, Soochow University, Suzhou City, Jiangsu, China
| | - Ning Xin
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China
| | - Bin Wei
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China
| | - Xiaodong Hua
- Department of Emergency, Emory University Hospital, Atlanta, GA, USA; Department of Biochemistry, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, USA
| | - Gaocai Zhang
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China; Institute of Neuroscience, Soochow University, Suzhou City, Jiangsu, China
| | - Cuihua Leng
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China; Institute of Neuroscience, Soochow University, Suzhou City, Jiangsu, China
| | - Chenyu Zhao
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China; Institute of Neuroscience, Soochow University, Suzhou City, Jiangsu, China
| | - Di Wu
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China; Institute of Neuroscience, Soochow University, Suzhou City, Jiangsu, China
| | - Jizhen Li
- Department of Neurology, Suzhou Kowloon Hospital, Suzhou City, China
| | - Wei Ge
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China; Department of Neurology, the Affiliated Hospital of Xuzhou Medical College, Xuzhou City, Jiangsu, China
| | - Miao Sun
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China.
| | - Xingshun Xu
- Department of Neurology, the Second Affiliated Hospital of Soochow University, Suzhou City, Jiangsu, China; Institute of Neuroscience, Soochow University, Suzhou City, Jiangsu, China.
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Mi Y, Gao X, Dai J, Ma Y, Xu L, Jin W. A Novel Function of TET2 in CNS: Sustaining Neuronal Survival. Int J Mol Sci 2015; 16:21846-57. [PMID: 26378518 PMCID: PMC4613284 DOI: 10.3390/ijms160921846] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 08/19/2015] [Accepted: 09/01/2015] [Indexed: 11/16/2022] Open
Abstract
DNA dioxygenases Ten-Eleven Translocation (TET) proteins can catalyze the conversion of 5-methylcytosine (5mC) of DNA to 5-hydroxymethylcytosine (5hmC), and thereby alter the epigenetic state of DNA. The TET family includes TET1, TET2 and TET3 members in mammals. Recently, accumulative research uncovered that TET1-3 occur abundantly in the central nervous system (CNS), and their biological functions have just begun to be investigated. In the present study, we demonstrated that mRNA and protein of TET2 were highly expressed in the cerebral cortex and hippocampus along the whole brain-development process. Further studies showed that TET2 was expressed in various types of cells, especially in most neurons. Subcellular distribution pattern implicated that TET2 is localized in both nucleus and cytoplasm of neurons. Down-regulation of TET2 in cultured cortical neurons with RNA interference implied that TET2 was required for cell survival. In all, our results indicate that neuronal TET2 is positively involved in the regulation of cell survival.
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Affiliation(s)
- Yajing Mi
- State Key Laboratory of Military Stomatology, Department of Anesthesiology, School of Stomatology, the Fourth Military Medical University, Xi'an 710032, China.
- Institute of Basic Medicine Science, Xi'an Medical University, Xi'an 710021, China.
| | - Xingchun Gao
- Institute of Basic Medicine Science, Xi'an Medical University, Xi'an 710021, China.
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Jinxiang Dai
- Department of Cell and Developmental Biology, University of Colorado Denver, Denver, CO 80045, USA.
| | - Yue Ma
- Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Engineering, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
| | - Lixian Xu
- State Key Laboratory of Military Stomatology, Department of Anesthesiology, School of Stomatology, the Fourth Military Medical University, Xi'an 710032, China.
| | - Weilin Jin
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
- Institute of Nano Biomedicine and Engineering, Department of Instrument Science and Engineering, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, School of Electronic Information and Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
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