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Fremuth LE, Hu H, van de Vlekkert D, Annunziata I, Weesner JA, Gomero E, d'Azzo A. Neuraminidase 1 regulates the cellular state of microglia by modulating the sialylation of Trem2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.20.595036. [PMID: 38826426 PMCID: PMC11142087 DOI: 10.1101/2024.05.20.595036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Neuraminidase 1 (Neu1) cleaves terminal sialic acids from sialoglycoproteins in endolysosomes and at the plasma membrane. As such, Neu1 regulates immune cells, primarily those of the monocytic lineage. Here we examined how Neu1 influences microglia by modulating the sialylation of full-length Trem2 (Trem2-FL), a multifunctional receptor that regulates microglial survival, phagocytosis, and cytokine production. When Neu1 was deficient/downregulated, Trem2-FL remained sialylated, accumulated intracellularly, and was excessively cleaved into a C-terminal fragment (Trem2-CTF) and an extracellular soluble domain (sTrem2), enhancing their signaling capacities. Sialylated Trem2-FL (Sia-Trem2-FL) did not hinder Trem2-FL-DAP12-Syk complex assembly but impaired signal transduction through Syk, ultimately abolishing Trem2-dependent phagocytosis. Concurrently, Trem2-CTF-DAP12 complexes dampened NFκB signaling, while sTrem2 propagated Akt-dependent cell survival and NFAT1-mediated production of TNFα and CCL3. Because Neu1 and Trem2 are implicated in neurodegenerative/neuroinflammatory diseases, including Alzheimer disease (AD) and sialidosis, modulating Neu1 activity represents a therapeutic approach to broadly regulate microglia-mediated neuroinflammation.
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Abdolmaleky HM, Martin M, Zhou JR, Thiagalingam S. Epigenetic Alterations of Brain Non-Neuronal Cells in Major Mental Diseases. Genes (Basel) 2023; 14:896. [PMID: 37107654 PMCID: PMC10137903 DOI: 10.3390/genes14040896] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/22/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
The tissue-specific expression and epigenetic dysregulation of many genes in cells derived from the postmortem brains of patients have been reported to provide a fundamental biological framework for major mental diseases such as autism, schizophrenia, bipolar disorder, and major depression. However, until recently, the impact of non-neuronal brain cells, which arises due to cell-type-specific alterations, has not been adequately scrutinized; this is because of the absence of techniques that directly evaluate their functionality. With the emergence of single-cell technologies, such as RNA sequencing (RNA-seq) and other novel techniques, various studies have now started to uncover the cell-type-specific expression and DNA methylation regulation of many genes (e.g., TREM2, MECP2, SLC1A2, TGFB2, NTRK2, S100B, KCNJ10, and HMGB1, and several complement genes such as C1q, C3, C3R, and C4) in the non-neuronal brain cells involved in the pathogenesis of mental diseases. Additionally, several lines of experimental evidence indicate that inflammation and inflammation-induced oxidative stress, as well as many insidious/latent infectious elements including the gut microbiome, alter the expression status and the epigenetic landscapes of brain non-neuronal cells. Here, we present supporting evidence highlighting the importance of the contribution of the brain's non-neuronal cells (in particular, microglia and different types of astrocytes) in the pathogenesis of mental diseases. Furthermore, we also address the potential impacts of the gut microbiome in the dysfunction of enteric and brain glia, as well as astrocytes, which, in turn, may affect neuronal functions in mental disorders. Finally, we present evidence that supports that microbiota transplantations from the affected individuals or mice provoke the corresponding disease-like behavior in the recipient mice, while specific bacterial species may have beneficial effects.
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Affiliation(s)
- Hamid Mostafavi Abdolmaleky
- Department of Medicine (Biomedical Genetics), Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA;
- Department of Surgery, Nutrition/Metabolism Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Marian Martin
- Department of Neurology, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Jin-Rong Zhou
- Department of Surgery, Nutrition/Metabolism Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Sam Thiagalingam
- Department of Medicine (Biomedical Genetics), Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA;
- Department of Pathology & Laboratory Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
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Dnmt1/Tet2-mediated changes in Cmip methylation regulate the development of nonalcoholic fatty liver disease by controlling the Gbp2-Pparγ-CD36 axis. Exp Mol Med 2023; 55:143-157. [PMID: 36609599 PMCID: PMC9898513 DOI: 10.1038/s12276-022-00919-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/17/2022] [Accepted: 11/13/2022] [Indexed: 01/07/2023] Open
Abstract
Dynamic alteration of DNA methylation leads to various human diseases, including nonalcoholic fatty liver disease (NAFLD). Although C-Maf-inducing protein (Cmip) has been reported to be associated with NAFLD, its exact underlying mechanism remains unclear. Here, we aimed to elucidate this mechanism in NAFLD in vitro and in vivo. We first identified alterations in the methylation status of the Cmip intron 1 region in mouse liver tissues with high-fat high-sucrose diet-induced NAFLD. Knockdown of DNA methyltransferase (Dnmt) 1 significantly increased Cmip expression. Chromatin immunoprecipitation assays of AML12 cells treated with oleic and palmitic acid (OPA) revealed that Dnmt1 was dissociated and that methylation of H3K27me3 was significantly decreased in the Cmip intron 1 region. Conversely, the knockdown of Tet methylcytosine dioxygenase 2 (Tet2) decreased Cmip expression. Following OPA treatment, the CCCTC-binding factor (Ctcf) was recruited, and H3K4me3 was significantly hypermethylated. Intravenous Cmip siRNA injection ameliorated NAFLD pathogenic features in ob/ob mice. Additionally, Pparγ and Cd36 expression levels were dramatically decreased in the livers of ob/ob mice administered siCmip, and RNA sequencing revealed that Gbp2 was involved. Gbp2 knockdown also induced a decrease in Pparγ and Cd36 expression, resulting in the abrogation of fatty acid uptake into cells. Our data demonstrate that Cmip and Gbp2 expression levels are enhanced in human liver tissues bearing NAFLD features. We also show that Dnmt1-Trt2/Ctcf-mediated reversible modulation of Cmip methylation regulates the Gbp2-Pparγ-Cd36 signaling pathway, indicating the potential of Cmip as a novel therapeutic target for NAFLD.
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Zhang P, Li Y, Wang K, Huang J, Su BB, Xu C, Wang Z, Tan S, Yang F, Tan Y. Altered DNA methylation of CYP2E1 gene in schizophrenia patients with tardive dyskinesia. BMC Med Genomics 2022; 15:253. [PMID: 36494682 PMCID: PMC9733323 DOI: 10.1186/s12920-022-01404-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND About 20-30% of patients with schizophrenia develop tardive dyskinesia (TD). Oxidative stress is one potential causes of TD. CYP2E1 is considered as an oxidative stress-related gene, however, no study has been reported on the DNA methylation levels of the CYP2E1 in schizophrenia or TD. METHODS A total of 35 schizophrenia patients with TD, 35 schizophrenia patients without TD (NTD), and 35 health controls (HCs) were collected in Beijing, China. DNA was extracted from peripheral blood samples. The promoter methylation levels of CYP2E1 were detected using pyrosequencing. The generalized linear model (GLM) was used to examine the methylation levels of three CpG sites among three diagnostic groups (TD vs. NTD vs. HC). RESULTS The average methylation levels were 8.8 ± 10.0, 14.5 ± 11.9 and 15.1 ± 11.3 in TD, NTD and HC groups, respectively. The F-test in GLM revealed overall differences in the average of methylation levels of three CpG sites among three diagnostic groups (p = 0.0227) and in the third CpG site (p = 0.0026). Furthermore, the TD group had lower average methylation levels than HC and NTD groups (p = 0.0115 and 0.0268, respectively). Specifically, TD group showed lower methylation levels in the third CpG site than HC and NTD groups (p = 0.0012 and 0.0072, respectively). Additionally, associations of the methylation levels with clinical features in the TD group were observed using Spearman correlation analysis. CONCLUSION This study provides the first evidence of DNA methylation levels in the promoter of CYP2E1 gene associated with schizophrenia and TD. The abnormal DNA methylation might serve as a potential mechanism for TD.
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Affiliation(s)
- Ping Zhang
- grid.11135.370000 0001 2256 9319Beijing HuiLongGuan Hospital, Peking University HuiLongGuan Clinical Medical School, Beijing, 100096 China
| | - Yanli Li
- grid.11135.370000 0001 2256 9319Beijing HuiLongGuan Hospital, Peking University HuiLongGuan Clinical Medical School, Beijing, 100096 China
| | - Kesheng Wang
- grid.268154.c0000 0001 2156 6140Department of Family and Community Health, Robert C. Byrd Health Sciences Center, School of Nursing, West Virginia University, Morgantown, WV 26506 USA
| | - Junchao Huang
- grid.11135.370000 0001 2256 9319Beijing HuiLongGuan Hospital, Peking University HuiLongGuan Clinical Medical School, Beijing, 100096 China
| | - Brenda Bin Su
- grid.449717.80000 0004 5374 269XDepartment of Health and Biomedical Sciences, College of Health Affairs, University of Texas Rio Grande Valle, Brownsville, TX USA
| | - Chun Xu
- grid.449717.80000 0004 5374 269XDepartment of Health and Biomedical Sciences, College of Health Affairs, University of Texas Rio Grande Valle, Brownsville, TX USA
| | - Zhiren Wang
- grid.11135.370000 0001 2256 9319Beijing HuiLongGuan Hospital, Peking University HuiLongGuan Clinical Medical School, Beijing, 100096 China
| | - Shuping Tan
- grid.11135.370000 0001 2256 9319Beijing HuiLongGuan Hospital, Peking University HuiLongGuan Clinical Medical School, Beijing, 100096 China
| | - Fude Yang
- grid.11135.370000 0001 2256 9319Beijing HuiLongGuan Hospital, Peking University HuiLongGuan Clinical Medical School, Beijing, 100096 China
| | - Yunlong Tan
- grid.11135.370000 0001 2256 9319Beijing HuiLongGuan Hospital, Peking University HuiLongGuan Clinical Medical School, Beijing, 100096 China
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Profile of TREM2-Derived circRNA and mRNA Variants in the Entorhinal Cortex of Alzheimer’s Disease Patients. Int J Mol Sci 2022; 23:ijms23147682. [PMID: 35887031 PMCID: PMC9320643 DOI: 10.3390/ijms23147682] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/04/2022] [Accepted: 07/04/2022] [Indexed: 02/04/2023] Open
Abstract
Genetic variants in TREM2, a microglia-related gene, are well-known risk factors for Alzheimer’s disease (AD). Here, we report that TREM2 originates from circular RNAs (circRNAs), a novel class of non-coding RNAs characterized by a covalent and stable closed-loop structure. First, divergent primers were designed to amplify circRNAs by RT-PCR, which were further assessed by Sanger sequencing. Then, additional primer sets were used to confirm back-splicing junctions. In addition, HMC3 cells were used to assess the microglial expression of circTREM2s. Three candidate circTREM2s were identified in control and AD human entorhinal samples. One of the circRNAs, circTREM2_1, was consistently amplified by all divergent primer sets in control and AD entorhinal cortex samples as well as in HMC3 cells. In AD cases, a moderate negative correlation (r = −0.434) was found between the global average area of Aβ deposits in the entorhinal cortex and circTREM2_1 expression level. In addition, by bioinformatics tools, a total of 16 miRNAs were predicted to join with circTREM2s. Finally, TREM2 mRNA corresponding to four isoforms was profiled by RT-qPCR. TREM2 mRNA levels were found elevated in entorhinal samples of AD patients with low or intermediate ABC scores compared to controls. To sum up, a novel circRNA derived from the TREM2 gene, circTREM2_1, has been identified in the human entorhinal cortex and TREM2 mRNA expression has been detected to increase in AD compared to controls. Unraveling the molecular genetics of the TREM2 gene may help to better know the innate immune response in AD.
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Lv Y, Zhang C, Jian H, Lou Y, Kang Y, Deng W, Wang C, Wang W, Shang S, Hou M, Shen W, Xie J, Li X, Zhou H, Feng S. Regulating DNA methylation could reduce neuronal ischemia response and apoptosis after ischemia-reperfusion injury. Gene 2022; 837:146689. [PMID: 35750086 DOI: 10.1016/j.gene.2022.146689] [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: 12/20/2021] [Revised: 06/05/2022] [Accepted: 06/17/2022] [Indexed: 11/04/2022]
Abstract
BACKGROUND Ischemia-reperfusion injury (IRI) is an important pathophysiological condition that can cause cell injury and large-scale tissue injury in the nervous system. Previous studies have shown that epigenetic regulation may play a role in the pathogenesis of IRI. METHODS In this study, we isolated mouse cortical neurons and constructed an oxygen-glucose deprivation/reoxygenation (OGD) model to explore the change in DNA methylation and its effect on the expression of corresponding genes. RESULTS We found that DNA methylation in neurons increased with hypoxia duration and that hypermethylation of numerous promoters and 3'-untranslated regions increased. We performed Gene Ontology enrichment analysis to study gene function and Kyoto Encyclopedia of Genes and Genomes pathway analysis to identify the pathways associated with gene regulation. The results showed that hypermethylation-related genes expressed after OGD were related to physiological pathways such as neuronal projection, ion transport, growth and development, while hypomethylation-related genes were related to pathological pathways such as the external apoptosis signaling pathway, neuronal death regulation, and regulation of oxidative stress. However, the changes in DNA methylation were specific for certain genes and may have been related to OGD-induced neuronal damage. Importantly, we integrated transcription and DNA methylation data to identify several candidate target genes, including hypomethylated Apoe, Pax6, Bmp4, and Ptch1 and hypermethylated Adora2a, Crhr1, Stxbp1, and Tac1. This study further indicated the effect of DNA methylation on gene function in brain IRI from the perspective of epigenetics, and the identified genes may become new targets for achieving neuroprotection in the brain after IRI.
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Affiliation(s)
- Yigang Lv
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Chi Zhang
- Department of Orthopaedics, Shandong University Centre for Orthopaedics, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China
| | - Huan Jian
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Yongfu Lou
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Yi Kang
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Weimin Deng
- Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Department of Immunology, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Chaoyu Wang
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Wei Wang
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Shenghui Shang
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Mengfan Hou
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Wenyuan Shen
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Jing Xie
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China
| | - Xueying Li
- Key Laboratory of Immuno Microenvironment and Disease of the Educational Ministry of China, Department of Immunology, Tianjin Medical University, Tianjin 300070, P.R. China; Shandong University Centre for Orthopaedics, Advanced Medical Research Institute, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China.
| | - Hengxing Zhou
- Department of Orthopaedics, Shandong University Centre for Orthopaedics, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China.
| | - Shiqing Feng
- Department of Orthopaedics, Tianjin Medical University General Hospital, International Science and Technology Cooperation Base of Spinal Cord Injury, Tianjin Key Laboratory of Spine and Spinal Cord, Tianjin 300052, P.R. China; Department of Orthopaedics, Shandong University Centre for Orthopaedics, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250012, P.R. China.
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Chen Q, Li D, Jin W, Shi Y, Li Z, Ma P, Sun J, Chen S, Li P, Lin P. Research Progress on the Correlation Between Epigenetics and Schizophrenia. Front Neurosci 2021; 15:688727. [PMID: 34366776 PMCID: PMC8334178 DOI: 10.3389/fnins.2021.688727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 06/03/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose of the Review Nowadays, the incidence of schizophrenia is noticeably increased. If left undiagnosed and untreated, it will lead to impaired social functions, repeated hospital admissions, decline in quality of life and life expectancy. However, the diagnosis of schizophrenia is complicated and challenging. Both genetic and environmental factors are considered as important contributors to the development and progression of this disorder. The environmental factors have been linked to changes in gene expression through epigenetic modulations, which have raised more and more research interests in recent years. This review article is to summarize the current findings and understanding of epigenetic modulation associated with pathogenesis of schizophrenia, aiming to provide useful information for further research in developing biomarkers for schizophrenia. Recent Findings Three major types of epigenetic modulations have been described in this article. Firstly, both DNA hypermethylation and hypomethylated have been associated with schizophrenia via analyzing post-mortem brain tissues and peripheral blood of patients. Specific changes of non-coding RNAs, particularly microRNAs and long-chain non-coding RNAs, have been observed in central and peripheral samples of schizophrenia patients, indicating their significant diagnostic value for the disease, and may also potentially predict treatment response. The correlation between histone modification and schizophrenia, however, is largely unclear. Summary Epigenetic modulations, including DNA methylation, ncRNA transcriptional regulation and histone modification, play an important role in the pathogenesis of schizophrenia. Therefore, tests of these epigenetic alterations may be utilized to assist in the diagnosis and determination of strategies of individualized treatment in clinical practice.
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Affiliation(s)
- Qing Chen
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dan Li
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Weifeng Jin
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yun Shi
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhenhua Li
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Peijun Ma
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jiaqi Sun
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuzi Chen
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ping Li
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ping Lin
- Clinical Laboratory, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Izuo N, Nitta A. New Insights Regarding Diagnosis and Medication for Schizophrenia Based on Neuronal Synapse-Microglia Interaction. J Pers Med 2021; 11:jpm11050371. [PMID: 34063598 PMCID: PMC8147599 DOI: 10.3390/jpm11050371] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 01/01/2023] Open
Abstract
Schizophrenia is a common psychiatric disorder that usually develops during adolescence and young adulthood. Since genetic and environmental factors are involved in the disease, the molecular status of the pathology of schizophrenia differs across patients. Recent genetic studies have focused on the association between schizophrenia and the immune system, especially microglia–synapse interactions. Microglia physiologically eliminate unnecessary synapses during the developmental period. The overactivation of synaptic pruning by microglia is involved in the pathology of brain disease. This paper focuses on the synaptic pruning function and its molecular machinery and introduces the hypothesis that excessive synaptic pruning plays a role in the development of schizophrenia. Finally, we suggest a strategy for diagnosis and medication based on modulation of the interaction between microglia and synapses. This review provides updated information on the involvement of the immune system in schizophrenia and proposes novel insights regarding diagnostic and therapeutic strategies for this disease.
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Affiliation(s)
| | - Atsumi Nitta
- Correspondence: ; Tel.: +81-76-415-8822 (ext. 8823); Fax: +81-76-415-8826
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Yoshida Y, Hayakawa K, Fujishiro M, Ikeda K, Tsushima H, Hirai T, Kawasaki M, Tominaga M, Suga Y, Takamori K, Watanabe Y, Sekigawa I, Morimoto S. Social defeat stress exacerbates atopic dermatitis through downregulation of DNA methyltransferase 1 and upregulation of C-C motif chemokine receptor 7 in skin dendritic cells. Biochem Biophys Res Commun 2020; 529:1073-1079. [PMID: 32819567 DOI: 10.1016/j.bbrc.2020.06.157] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 06/29/2020] [Indexed: 11/16/2022]
Abstract
DNA methylation is an epigenetic modification that regulates gene transcription. DNA methyltransferase 1 (DNMT1) plays an important role in DNA methylation. However, the involvement of DNMT1 and DNA methylation in the pathogenesis of atopic dermatitis (AD) remains unclear. In this study, microarray analysis revealed that peripheral blood mononuclear cells of AD patients with low DNMT1 expression (DNMT1-low) highly expressed dendritic cell (DC) activation-related genes. Also, DNMT1-low AD patients exhibited a higher itch score compared to AD patients with high DNMT1 expression (DNMT1-high). By using an AD-like mouse model induced by the application of Dermatophagoides farinae body ointment, we found that Dnmt1 expression was decreased, while the expression of C-C chemokine receptor type 7 (Ccr7) was upregulated in mouse skin DCs. Furthermore, mice exposed to social defeat stress exhibited Dnmt1 downregulation and Ccr7 upregulation in skin DCs. Additionally, dermatitis and itch-related scratching behavior were exacerbated in AD mice exposed to stress. The relationship between low DNMT1 and itch induction was found in both human AD patients and AD mice. In mouse bone marrow-derived DCs, Ccr7 expression was inhibited by 5-aza-2-deoxycytidine, a methylation inhibitor. Furthermore, in mouse skin DCs, methylation of CpG sites in Ccr7 was modified by either AD induction or social defeat stress. Collectively, these findings suggest that social defeat stress exacerbates AD pathology through Dnmt1 downregulation and Ccr7 upregulation in mouse skin DCs. The data also suggest a role of DNMT1 downregulation in the exacerbation of AD pathology.
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Affiliation(s)
- Yuko Yoshida
- Department of Pharmaceutical Sciences, Musashino University, Tokyo, 202-8585, Japan; Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan.
| | - Kunihiro Hayakawa
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan
| | - Maki Fujishiro
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan
| | - Keigo Ikeda
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Department of Internal Medicine and Rheumatology, Juntendo University, Urayasu Hospital, Chiba, 279-0021, Japan
| | - Hiroshi Tsushima
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Department of Internal Medicine and Rheumatology, Juntendo University, Urayasu Hospital, Chiba, 279-0021, Japan
| | - Takuya Hirai
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Department of Internal Medicine and Rheumatology, Juntendo University, Urayasu Hospital, Chiba, 279-0021, Japan
| | - Mikiko Kawasaki
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan
| | - Mitsutoshi Tominaga
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Juntendo Itch Research Center, Institute for Environment and Gender Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan
| | - Yasushi Suga
- Department of Dermatology, Juntendo University, Urayasu Hospital, Chiba, 279-0021, Japan
| | - Kenji Takamori
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Juntendo Itch Research Center, Institute for Environment and Gender Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Department of Dermatology, Juntendo University, Urayasu Hospital, Chiba, 279-0021, Japan
| | - Yoshifumi Watanabe
- Department of Pharmaceutical Sciences, Musashino University, Tokyo, 202-8585, Japan
| | - Iwao Sekigawa
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Department of Internal Medicine and Rheumatology, Juntendo University, Urayasu Hospital, Chiba, 279-0021, Japan
| | - Shinji Morimoto
- Institute for Environment and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan; Department of Internal Medicine and Rheumatology, Juntendo University, Urayasu Hospital, Chiba, 279-0021, Japan
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Smigielski L, Jagannath V, Rössler W, Walitza S, Grünblatt E. Epigenetic mechanisms in schizophrenia and other psychotic disorders: a systematic review of empirical human findings. Mol Psychiatry 2020; 25:1718-1748. [PMID: 31907379 DOI: 10.1038/s41380-019-0601-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 11/05/2019] [Accepted: 11/07/2019] [Indexed: 12/26/2022]
Abstract
Schizophrenia and other psychotic disorders are highly debilitating psychiatric conditions that lack a clear etiology and exhibit polygenic inheritance underlain by pleiotropic genes. The prevailing explanation points to the interplay between predisposing genes and environmental exposure. Accumulated evidence suggests that epigenetic regulation of the genome may mediate dynamic gene-environment interactions at the molecular level by modulating the expression of psychiatric phenotypes through transcription factors. This systematic review summarizes the current knowledge linking schizophrenia and other psychotic disorders to epigenetics, based on PubMed and Web of Science database searches conducted according to the PRISMA guidelines. Three groups of mechanisms in case-control studies of human tissue (i.e., postmortem brain and bio-fluids) were considered: DNA methylation, histone modifications, and non-coding miRNAs. From the initial pool of 3,204 records, 152 studies met our inclusion criteria (11,815/11,528, 233/219, and 2,091/1,827 cases/controls for each group, respectively). Many of the findings revealed associations with epigenetic modulations of genes regulating neurotransmission, neurodevelopment, and immune function, as well as differential miRNA expression (e.g., upregulated miR-34a, miR-7, and miR-181b). Overall, actual evidence moderately supports an association between epigenetics and schizophrenia and other psychotic disorders. However, heterogeneous results and cross-tissue extrapolations call for future work. Integrating epigenetics into systems biology may critically enhance research on psychosis and thus our understanding of the disorder. This may have implications for psychiatry in risk stratification, early recognition, diagnostics, precision medicine, and other interventional approaches targeting epigenetic fingerprints.
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Affiliation(s)
- Lukasz Smigielski
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of Psychiatry Zurich, University of Zurich, Zurich, Switzerland. .,The Zurich Program for Sustainable Development of Mental Health Services (ZInEP), University Hospital of Psychiatry Zurich, Zurich, Switzerland.
| | - Vinita Jagannath
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of Psychiatry Zurich, University of Zurich, Zurich, Switzerland.,Merck Sharp & Dohme (MSD) R&D Innovation Centre, London, UK
| | - Wulf Rössler
- The Zurich Program for Sustainable Development of Mental Health Services (ZInEP), University Hospital of Psychiatry Zurich, Zurich, Switzerland.,Department of Psychiatry, Psychotherapy and Psychosomatics, University Hospital of Psychiatry, University of Zurich, Zurich, Switzerland.,Department of Psychiatry and Psychotherapy, Charité Universitätsmedizin, Berlin, Germany.,Laboratory of Neuroscience, Institute of Psychiatry, Universidade de São Paulo, São Paulo, Brazil
| | - Susanne Walitza
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of Psychiatry Zurich, University of Zurich, Zurich, Switzerland.,The Zurich Program for Sustainable Development of Mental Health Services (ZInEP), University Hospital of Psychiatry Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Edna Grünblatt
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital of Psychiatry Zurich, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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11
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Lovšin E, Kovač J, Tesovnik T, Toplak N, Perko D, Rozmarič T, Debeljak M, Avčin T. PIK3AP1 and SPON2 Genes Are Differentially Methylated in Patients With Periodic Fever, Aphthous Stomatitis, Pharyngitis, and Adenitis (PFAPA) Syndrome. Front Immunol 2020; 11:1322. [PMID: 32793186 PMCID: PMC7390842 DOI: 10.3389/fimmu.2020.01322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/26/2020] [Indexed: 12/22/2022] Open
Abstract
Periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome is the most common autoinflammatory disease in children and is often grouped together with hereditary periodic fever syndromes, although its cause and hereditary nature remain unexplained. We investigated whether differential DNA methylation was present in DNA from peripheral blood mononuclear cells (PBMC) in patients with PFAPA vs. healthy controls. A whole-epigenome analysis (MeDIP and MBD) was performed using pooled DNA libraries enriched for methylated genomic regions and identified candidate genes, two of which were further evaluated with methylation-specific restriction enzymes coupled with qPCR (MSRE-qPCR). The analysis showed that the PIK3AP1 and SPON2 gene regions are differentially methylated in patients with PFAPA. MSRE-qPCR proved to be a quick, reliable, and cost-effective method of confirming results from MeDIP and MBD. Our findings indicate that a B-cell adapter protein (PIK3AP1), as the PI3K binding inhibitor of inflammation, and spondin-2 (SPON2), as a pattern recognition molecule and integrin ligand, could play a role in the etiology of PFAPA. Their role and the impact of changed DNA methylation in PFAPA etiology and autoinflammation need further investigation.
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Affiliation(s)
- Ema Lovšin
- Department of Allergology, Rheumatology and Clinical Immunology, University Medical Centre Ljubljana, University Children's Hospital, Ljubljana, Slovenia.,Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jernej Kovač
- Department for Special Laboratory Diagnostics, University Medical Centre Ljubljana, University Children's Hospital, Ljubljana, Slovenia
| | - Tine Tesovnik
- Department for Special Laboratory Diagnostics, University Medical Centre Ljubljana, University Children's Hospital, Ljubljana, Slovenia
| | - Nataša Toplak
- Department of Allergology, Rheumatology and Clinical Immunology, University Medical Centre Ljubljana, University Children's Hospital, Ljubljana, Slovenia.,Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Daša Perko
- Department for Special Laboratory Diagnostics, University Medical Centre Ljubljana, University Children's Hospital, Ljubljana, Slovenia
| | - Tomaž Rozmarič
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria
| | - Maruša Debeljak
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Department for Special Laboratory Diagnostics, University Medical Centre Ljubljana, University Children's Hospital, Ljubljana, Slovenia
| | - Tadej Avčin
- Department of Allergology, Rheumatology and Clinical Immunology, University Medical Centre Ljubljana, University Children's Hospital, Ljubljana, Slovenia.,Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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12
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Yang X, Xu S, Qian Y, He X, Chen S, Xiao Q. Hypermethylation of the Gene Coding for PGC-1α in Peripheral Blood Leukocytes of Patients With Parkinson's Disease. Front Neurosci 2020; 14:97. [PMID: 32174806 PMCID: PMC7054441 DOI: 10.3389/fnins.2020.00097] [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: 10/06/2019] [Accepted: 01/23/2020] [Indexed: 12/13/2022] Open
Abstract
Decreased expression of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) is implicated in the pathophysiology of Parkinson’s disease (PD). However, our understanding of the mechanism regulating the PGC-1α expression is still limited. We sought to determine whether the epigenetic modification of PPARGC1A (the gene encoding PGC-1α) could account for its diminished expression. We performed a study of PPARGC1A risk-SNP genotypes, methylation level, and the expression in blood from 171 subjects. The mean DNA methylation level of PPARGC1A intron 1 in patients with PD was higher than that in the controls (7.18 ± 1.74 vs. 6.36 ± 1.28, P = 0.007). A detailed comparison of the DNA methylation level at each CpG site showed that CpG_1, CpG_13.14, CpG_17.18, and CpG_20 were significantly hypermethylated in patients with PD. There was a significant negative correlation between PPARGC1A methylation and expression level (R = −0.404, P < 0.001). We found no correlations between the PPARGC1A methylation level and the clinical features, while the CpG_13.14 site methylation level was positively correlated with H&Y stage (R = 0.246, P = 0.020) and was increased in people carrying the rs2970848 AA genotype compared with that in carriers of the AG/GG genotype (7.27 ± 1.86 vs. 6.65 ± 1.92, P = 0.032). Our results support a link between PPARGC1A methylation, gene expression, and variability, which indicated that a novel epigenetic regulatory mechanism controlling PPARGC1A expression influences PD pathogenesis.
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Affiliation(s)
- Xiaodong Yang
- Department of Neurology, Ruijin Hospital Affiliated with the School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shaoqing Xu
- Department of Neurology, Ruijin Hospital Affiliated with the School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yiwei Qian
- Department of Neurology, Ruijin Hospital Affiliated with the School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoqin He
- Department of Neurology, Ruijin Hospital Affiliated with the School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shengdi Chen
- Department of Neurology, Ruijin Hospital Affiliated with the School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Qin Xiao
- Department of Neurology, Ruijin Hospital Affiliated with the School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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13
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Prefrontal cortex alterations in glia gene expression in schizophrenia with and without suicide. J Psychiatr Res 2020; 121:31-38. [PMID: 31739114 DOI: 10.1016/j.jpsychires.2019.11.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/01/2019] [Accepted: 11/08/2019] [Indexed: 01/15/2023]
Abstract
BACKGROUND Patients with schizophrenia (SCZ) run a lifelong risk of suicide. Alterations in glia activities in the prefrontal cortex (PFC) have been reported in relation to suicide in patients with SCZ. While immune processes in the CNS have been related to the susceptibility and course of SCZ, there are hardly any direct comparisons between individuals with SCZ, both those who died of natural causes and those that committed suicide, and healthy controls. MATERIALS AND METHODS We compared mRNA expression using real time qPCR of 16 glia-related genes in the dorsal lateral prefrontal cortex (DLPFC) and the anterior cingulate cortex (ACC) between 35 patients with SCZ (7 suicide completers and 28 patients who died of natural causes) and 34 well-matched controls without psychiatric or neurological diseases. RESULTS We found an increased expression of the astrocytic gene aldehyde dehydrogenase-1 family member L1 (ALDH1L1) mRNA, a marker involved in dopaminergic activity, in SCZ versus controls. Excluding individuals with SCZ that committed suicide resulted in an elevated expression in the DLPFC of both ALDH1L1 and glutamine synthetase (GS) genes in patients with SCZ, compared to suicide completers and non-psychiatric controls. Regarding microglia genes: in the ACC, homeostatic markers such as chemokine (C-X3-C motif) ligand 1 (CX3CR1) mRNA expression was increased in SCZ without suicide as compared to suicide completers, while no change was found when compared to controls. Another, purinergic receptor 12 (P2RY12) mRNA was exclusively elevated in the ACC of suicide completers, compared to either other group. Triggering receptor expressed on myeloid cells 2 (TREM2) expression, which maintains microglial metabolism, was reduced in non-suicide patients with SCZ, compared to suicide victims and control subjects. CONCLUSIONS Differential changes are found in astrocyte and microglia genes in the PFC subregions in relation to SCZ and suicide, indicating possible disturbances of glia homeostasis in these conditions.
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14
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Yoshino Y, Funahashi Y, Nakata S, Ozaki Y, Yamazaki K, Yoshida T, Mori T, Mori Y, Ochi S, Iga JI, Ueno SI. Ghrelin cascade changes in the peripheral blood of Japanese patients with Alzheimer's disease. J Psychiatr Res 2018; 107:79-85. [PMID: 30366284 DOI: 10.1016/j.jpsychires.2018.10.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/17/2018] [Accepted: 10/18/2018] [Indexed: 11/26/2022]
Abstract
The neuroprotective effect of ghrelin has recently been reported in Alzheimer's disease (AD). Ghrelin is converted from des-acyl ghrelin to the activated form, acyl ghrelin, by membrane bound o-acyltransferase 4 (MBOAT4), and then binds to growth hormone secretagogue receptor (GHS-R). We examined the levels of plasma acyl/des-acyl ghrelin in 75 AD subjects and age- and sex-matched controls, as well as the DNA methylation and mRNA expression of MBOAT4 and GHS-R in peripheral leukocytes. The acyl ghrelin concentration was significantly higher in AD subjects than in controls (2.18 ± 1.25 vs. 1.49 ± 2.3, p = 0.001). The methylation rate of MBOAT4 CpG 2 was significantly lower in AD subjects than in controls (4.0 ± 0.9 vs. 4.7 ± 1.2, p < 0.001). The mRNA expression levels of MBOAT4 and GHS-R1b were significantly higher in AD subjects than in controls (MBOAT4: 1.10 ± 0.48 vs. 1.0 ± 0.55, p = 0.049; GHS-R1b: 1.76 ± 3.18 vs. 1.0 ± 1.56, p = 0.030). These changes in the ghrelin cascade in peripheral blood may reflect those in the brain, and may be a neuroprotective biomarker in AD.
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Affiliation(s)
- Yuta Yoshino
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Yu Funahashi
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Shunsuke Nakata
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Yuki Ozaki
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Kiyohiro Yamazaki
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Taku Yoshida
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Takaaki Mori
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Yoko Mori
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Shinichiro Ochi
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Jun-Ichi Iga
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan.
| | - Shu-Ichi Ueno
- Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan
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15
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Anastasiadi D, Esteve-Codina A, Piferrer F. Consistent inverse correlation between DNA methylation of the first intron and gene expression across tissues and species. Epigenetics Chromatin 2018; 11:37. [PMID: 29958539 PMCID: PMC6025724 DOI: 10.1186/s13072-018-0205-1] [Citation(s) in RCA: 228] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/19/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND DNA methylation is one of the main epigenetic mechanisms for the regulation of gene expression in eukaryotes. In the standard model, methylation in gene promoters has received the most attention since it is generally associated with transcriptional silencing. Nevertheless, recent studies in human tissues reveal that methylation of the region downstream of the transcription start site is highly informative of gene expression. Also, in some cell types and specific genes it has been found that methylation of the first intron, a gene feature typically rich in enhancers, is linked with gene expression. However, a genome-wide, tissue-independent, systematic comparative analysis of the relationship between DNA methylation in the first intron and gene expression across vertebrates has not been explored yet. RESULTS The most important findings of this study are: (1) using different tissues from a modern fish, we show a clear genome-wide, tissue-independent quasi-linear inverse relationship between DNA methylation of the first intron and gene expression. (2) This relationship is conserved across vertebrates, since it is also present in the genomes of a model pufferfish, a model frog and different human tissues. Among the gene features, tissues and species interrogated, the first intron's negative correlation with the gene expression was most consistent. (3) We identified more tissue-specific differentially methylated regions (tDMRs) in the first intron than in any other gene feature. These tDMRs have positive or negative correlation with gene expression, indicative of distinct mechanisms of tissue-specific regulation. (4) Lastly, we identified CpGs in transcription factor binding motifs, enriched in the first intron, the methylation of which tended to increase with the distance from the first exon-first intron boundary, with a concomitant decrease in gene expression. CONCLUSIONS Our integrative analysis clearly reveals the important and conserved role of the methylation level of the first intron and its inverse association with gene expression regardless of tissue and species. These findings not only contribute to our basic understanding of the epigenetic regulation of gene expression but also identify the first intron as an informative gene feature regarding the relationship between DNA methylation and gene expression where future studies should be focused.
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Affiliation(s)
- Dafni Anastasiadi
- Institute of Marine Sciences (ICM-CSIC), Passeig Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain
| | - Anna Esteve-Codina
- CNAG-CRG, Center for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Baldiri i Reixac 4, 08028, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Francesc Piferrer
- Institute of Marine Sciences (ICM-CSIC), Passeig Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain.
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