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Epigenetic Mechanisms in Memory and Cognitive Decline Associated with Aging and Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms222212280. [PMID: 34830163 PMCID: PMC8618067 DOI: 10.3390/ijms222212280] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 12/21/2022] Open
Abstract
Epigenetic mechanisms, which include DNA methylation, a variety of post-translational modifications of histone proteins (acetylation, phosphorylation, methylation, ubiquitination, sumoylation, serotonylation, dopaminylation), chromatin remodeling enzymes, and long non-coding RNAs, are robust regulators of activity-dependent changes in gene transcription. In the brain, many of these epigenetic modifications have been widely implicated in synaptic plasticity and memory formation. Dysregulation of epigenetic mechanisms has been reported in the aged brain and is associated with or contributes to memory decline across the lifespan. Furthermore, alterations in the epigenome have been reported in neurodegenerative disorders, including Alzheimer’s disease. Here, we review the diverse types of epigenetic modifications and their role in activity- and learning-dependent synaptic plasticity. We then discuss how these mechanisms become dysregulated across the lifespan and contribute to memory loss with age and in Alzheimer’s disease. Collectively, the evidence reviewed here strongly supports a role for diverse epigenetic mechanisms in memory formation, aging, and neurodegeneration in the brain.
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High Methionine Diet-Induced Alzheimer's Disease like Symptoms Are Accompanied by 5-Methylcytosine Elevated Levels in the Brain. Behav Neurol 2021; 2021:6683318. [PMID: 33880134 PMCID: PMC8046555 DOI: 10.1155/2021/6683318] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 03/16/2021] [Accepted: 03/23/2021] [Indexed: 01/09/2023] Open
Abstract
Background Excessive or insufficient intake of methionine (Met) causes neuronal dysfunction, neurodegeneration, cerebrovascular dysfunction, vascular leakage, and short-term memory loss, which result in the occurrence of Alzheimer's disease- (AD-) like symptoms. Objective To determine the relationship between high methionine diets (HMD) induced AD-like symptoms and 5-methylcytosine (5-mC) level. Methods C57BL/6J mice were randomly divided into two groups: the control group (Maintain diets) and the model group (2% HMD). Mice were fed with 2% HMD for 9 weeks. Animals were weighed and food intake was recorded weekly. Open field test, nesting ability test, Y maze test, new object recognition test, and Morris water maze test were used to detect the motor, learning, and memory ability. Hematoxylin-eosin (HE) staining was used to observe the damage of cells in hippocampus and cortex. Immunofluorescence (IF) staining was used to detect the expression and distribution of amyloid-β 1-40 (Aβ1-40), amyloid-β 1-42 (Aβ1-42), and 5-methylcytosine (5-mC) in hippocampus and cortex. Western blotting (WB) was used to determine the expression of Aβ and DNA methyltransferases- (DNMTs-) related proteins in the cortex. Enzyme-linked immunosorbent assay (ELISA) was performed to detect homocysteine (Hcy) level (ELISA). Results Feeding of HMD decreased the body weight and food intake of mice. Behavioral testing revealed that HMD caused learning, memory, and motor ability impairment in the mice. HE staining results showed that HMD feeding caused damage of hippocampal and cortical neurons, along with disordered cell arrangement, and loss of neurons. Furthermore, HMD increased the contents of Aβ1-40, Aβ1-42, and 5-mC in the hippocampus and cortex. WB results showed that HMD increased the expression of Aβ production-related proteins, such as amyloid precursor protein (APP) and beta-secretase 1 (BACE1), and decreased the expression of Aβ metabolism-related protein in the cortex, including insulin-degrading enzyme (IDE) and neprilysin (NEP). Additionally, the decreased expression of DNA methyltransferase1 (DNMT1) was observed in HMD-treated mice, but there was no significant change of DNMT3a level. ELISA results showed that HMD increased the levels of Hcy in serum. Conclusion Our result suggested that the HMD can cause neurotoxicity, leading to AD-like symptoms in mice, which may be related to 5-mC elevated.
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Yu CC, He C, Du YJ, Gao S, Lin YF, Wang SQ, Wang L, Wang J, Wang XS, Jiang T, Kong LH. Preventive electroacupuncture reduces cognitive deficits in a rat model of D-galactose-induced aging. Neural Regen Res 2021; 16:916-923. [PMID: 33229729 PMCID: PMC8178792 DOI: 10.4103/1673-5374.297090] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Acupuncture can reduce cognitive deficits in Alzheimer’s disease. However, whether electroacupuncture can prevent or alleviate the cognitive deficits in animal models of aging remains poorly understood. Studies have shown that disordered epigenetic modifications play a critical role in age-related cognitive decline. Therefore, we hypothesized that preventive electroacupuncture might improve cognitive functions during aging by regulating epigenetic modifications. A rat model of aging was produced by intraperitoneal injection of 120 mg/kg D-galactose for 8 weeks. Baihui and Shenshu acupoints were stimulated by electroacupuncture for 8 weeks from the first day of D-galactose administration. Preventive electroacupuncture alleviated memory impairment, decreased tau hyperphosphorylation, and reduced glycogen synthase kinase-3β protein and mRNA expression levels in the brainstem dorsal raphe nucleus, where intracellular neurofibrillary tangle lesions first occur. In addition, the DNA methylation level in the promoter region of the glycogen synthase kinase-3β gene was increased. The effects of preventive electroacupuncture were stronger than those of preventive acupuncture. Intraperitoneal injection of 0.4 mg/kg 5-aza-2′-deoxycytidine, an inhibitor of DNA methyltransferase that blocks epigenetic modifications, antagonized the effects of preventive electroacupuncture. Our results suggest that preventive electroacupuncture treatment alleviates cognitive impairment in aging rats probably by affecting the epigenetic modification of the glycogen synthase kinase-3β gene in the dorsal raphe nucleus. This study was approved by the Animal Ethics Committee of Hubei University of Chinese Medicine, China (approval No. HUCMS201712001) on November 28, 2017.
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Affiliation(s)
- Chao-Chao Yu
- Department of Tuina, Shenzhen Traditional Chinese Medicine Hospital; The 4th Clinical College, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong Province, China
| | - Chuan He
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Yan-Jun Du
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Shan Gao
- Department of Acupuncture & Moxibustion, Wuhan Hospital of Integrated Chinese & Western Medicine, Tongji Medical College of Huazhong University of Science & Technology, Wuhan, Hubei Province, China
| | - Yuan-Fang Lin
- Department of Tuina, Shenzhen Traditional Chinese Medicine Hospital; The 4th Clinical College, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong Province, China
| | - Shu-Qin Wang
- Department of Tuina, Shenzhen Traditional Chinese Medicine Hospital; The 4th Clinical College, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong Province, China
| | - Li Wang
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Jia Wang
- Department of Acupuncture & Moxibustion, Wuhan Hospital of Integrated Chinese & Western Medicine, Tongji Medical College of Huazhong University of Science & Technology, Wuhan, Hubei Province, China
| | - Xue-Song Wang
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Tao Jiang
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
| | - Li-Hong Kong
- College of Acupuncture and Orthopedics, Hubei University of Chinese Medicine, Wuhan, Hubei Province, China
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Tiane A, Schepers M, Rombaut B, Hupperts R, Prickaerts J, Hellings N, van den Hove D, Vanmierlo T. From OPC to Oligodendrocyte: An Epigenetic Journey. Cells 2019; 8:E1236. [PMID: 31614602 PMCID: PMC6830107 DOI: 10.3390/cells8101236] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/08/2019] [Accepted: 10/10/2019] [Indexed: 12/15/2022] Open
Abstract
Oligodendrocytes provide metabolic and functional support to neuronal cells, rendering them key players in the functioning of the central nervous system. Oligodendrocytes need to be newly formed from a pool of oligodendrocyte precursor cells (OPCs). The differentiation of OPCs into mature and myelinating cells is a multistep process, tightly controlled by spatiotemporal activation and repression of specific growth and transcription factors. While oligodendrocyte turnover is rather slow under physiological conditions, a disruption in this balanced differentiation process, for example in case of a differentiation block, could have devastating consequences during ageing and in pathological conditions, such as multiple sclerosis. Over the recent years, increasing evidence has shown that epigenetic mechanisms, such as DNA methylation, histone modifications, and microRNAs, are major contributors to OPC differentiation. In this review, we discuss how these epigenetic mechanisms orchestrate and influence oligodendrocyte maturation. These insights are a crucial starting point for studies that aim to identify the contribution of epigenetics in demyelinating diseases and may thus provide new therapeutic targets to induce myelin repair in the long run.
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Affiliation(s)
- Assia Tiane
- Department of Immunology, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium.
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6200 MD, The Netherlands.
| | - Melissa Schepers
- Department of Immunology, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium.
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6200 MD, The Netherlands.
| | - Ben Rombaut
- Department of Immunology, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium.
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6200 MD, The Netherlands.
| | - Raymond Hupperts
- Department of Neurology, Zuyderland Medical Center, Sittard-Geleen 6130 MB, The Netherlands.
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6200 MD, The Netherlands.
| | - Jos Prickaerts
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6200 MD, The Netherlands.
| | - Niels Hellings
- Department of Immunology, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium.
| | - Daniel van den Hove
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6200 MD, The Netherlands.
- Department of Psychiatry, Psychosomatics and Psychotherapy, University of Wuerzburg, Wuerzburg 97080, Germany.
| | - Tim Vanmierlo
- Department of Immunology, Biomedical Research Institute, Hasselt University, Hasselt 3500, Belgium.
- Department Psychiatry and Neuropsychology, European Graduate School of Neuroscience, School for Mental Health and Neuroscience, Maastricht University, Maastricht 6200 MD, The Netherlands.
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Consistent decrease in global DNA methylation and hydroxymethylation in the hippocampus of Alzheimer's disease patients. Neurobiol Aging 2013; 34:2091-9. [PMID: 23582657 DOI: 10.1016/j.neurobiolaging.2013.02.021] [Citation(s) in RCA: 289] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 02/17/2013] [Accepted: 02/21/2013] [Indexed: 11/21/2022]
Abstract
Epigenetic dysregulation of gene expression is thought to be critically involved in the pathophysiology of Alzheimer's disease (AD). Recent studies indicate that DNA methylation and DNA hydroxymethylation are 2 important epigenetic mechanisms that regulate gene expression in the aging brain. However, very little is known about the levels of markers of DNA methylation and hydroxymethylation in the brains of patients with AD, the cell-type specificity of putative AD-related alterations in these markers, as well as the link between epigenetic alterations and the gross pathology of AD. The present quantitative immunohistochemical study investigated the levels of the 2 most important markers of DNA methylation and hydroxymethylation, that is, 5-methylcytidine (5-mC) and 5-hydroxymethylcytidine (5-hmC), in the hippocampus of AD patients (n = 10) and compared these to non-demented, age-matched controls (n = 10). In addition, the levels of 5-hmC in the hippocampus of a pair of monozygotic twins discordant for AD were assessed. The levels of 5-mC and 5-hmC were furthermore analyzed in a cell-type and hippocampal subregion-specific manner, and were correlated with amyloid plaque load and neurofibrillary tangle load. The results showed robust decreases in the hippocampal levels of 5-mC and 5-hmC in AD patients (19.6% and 20.2%, respectively). Similar results were obtained for the twin with AD when compared to the non-demented co-twin. Moreover, levels of 5-mC as well as the levels of 5-hmC showed a significant negative correlation with amyloid plaque load in the hippocampus (r(p) = -0.539, p = 0.021 for 5-mC and r(p) = -0.558, p = 0.016 for 5-hmC). These human postmortem results thus strengthen the notion that AD is associated with alterations in DNA methylation and hydroxymethylation, and provide a basis for further epigenetic studies identifying the exact genetic loci with aberrant epigenetic signatures.
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