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Diabetologia Jul 2023Several studies have identified associations between type 2 diabetes and DNA methylation (DNAm). However, the causal role of these associations remains unclear. This... (Meta-Analysis)
Meta-Analysis
AIMS/HYPOTHESIS
Several studies have identified associations between type 2 diabetes and DNA methylation (DNAm). However, the causal role of these associations remains unclear. This study aimed to provide evidence for a causal relationship between DNAm and type 2 diabetes.
METHODS
We used bidirectional two-sample Mendelian randomisation (2SMR) to evaluate causality at 58 CpG sites previously detected in a meta-analysis of epigenome-wide association studies (meta-EWAS) of prevalent type 2 diabetes in European populations. We retrieved genetic proxies for type 2 diabetes and DNAm from the largest genome-wide association study (GWAS) available. We also used data from the Avon Longitudinal Study of Parents and Children (ALSPAC, UK) when associations of interest were not available in the larger datasets. We identified 62 independent SNPs as proxies for type 2 diabetes, and 39 methylation quantitative trait loci as proxies for 30 of the 58 type 2 diabetes-related CpGs. We applied the Bonferroni correction for multiple testing and inferred causality based on p<0.001 for the type 2 diabetes to DNAm direction and p<0.002 for the opposing DNAm to type 2 diabetes direction in the 2SMR analysis.
RESULTS
We found strong evidence of a causal effect of DNAm at cg25536676 (DHCR24) on type 2 diabetes. An increase in transformed residuals of DNAm at this site was associated with a 43% (OR 1.43, 95% CI 1.15, 1.78, p=0.001) higher risk of type 2 diabetes. We inferred a likely causal direction for the remaining CpG sites assessed. In silico analyses showed that the CpGs analysed were enriched for expression quantitative trait methylation sites (eQTMs) and for specific traits, dependent on the direction of causality predicted by the 2SMR analysis.
CONCLUSIONS/INTERPRETATION
We identified one CpG mapping to a gene related to the metabolism of lipids (DHCR24) as a novel causal biomarker for risk of type 2 diabetes. CpGs within the same gene region have previously been associated with type 2 diabetes-related traits in observational studies (BMI, waist circumference, HDL-cholesterol, insulin) and in Mendelian randomisation analyses (LDL-cholesterol). Thus, we hypothesise that our candidate CpG in DHCR24 may be a causal mediator of the association between known modifiable risk factors and type 2 diabetes. Formal causal mediation analysis should be implemented to further validate this assumption.
Topics: Child; Humans; DNA Methylation; Diabetes Mellitus, Type 2; Longitudinal Studies; Genome-Wide Association Study; Cholesterol
PubMed: 37202507
DOI: 10.1007/s00125-023-05914-7 -
Advanced Science (Weinheim,... Jul 2023While extensive investigations have been devoted to the study of genetic pathways related to fatty liver diseases, much less is known about epigenetic mechanisms...
While extensive investigations have been devoted to the study of genetic pathways related to fatty liver diseases, much less is known about epigenetic mechanisms underlying these disorders. DNA methylation is an epigenetic link between environmental factors (e.g., diets) and complex diseases (e.g., non-alcoholic fatty liver disease). Here, it is aimed to study the role of DNA methylation in the regulation of hepatic lipid metabolism. A dynamic change in the DNA methylome in the liver of high-fat diet (HFD)-fed mice is discovered, including a marked increase in DNA methylation at the promoter of Beta-klotho (Klb), a co-receptor for the biological functions of fibroblast growth factor (FGF)15/19 and FGF21. DNA methyltransferases (DNMT) 1 and 3A mediate HFD-induced methylation at the Klb promoter. Notably, HFD enhances DNMT1 protein stability via a ubiquitination-mediated mechanism. Liver-specific deletion of Dnmt1 or 3a increases Klb expression and ameliorates HFD-induced hepatic steatosis. Single-nucleus RNA sequencing analysis reveals pathways involved in fatty acid oxidation in Dnmt1-deficient hepatocytes. Targeted demethylation at the Klb promoter increases Klb expression and fatty acid oxidation, resulting in decreased hepatic lipid accumulation. Up-regulation of methyltransferases by HFD may induce hypermethylation of the Klb promoter and subsequent down-regulation of Klb expression, resulting in the development of hepatic steatosis.
Topics: Mice; Animals; Lipid Metabolism; DNA Methylation; Epigenesis, Genetic; Fatty Liver; Fatty Acids
PubMed: 37282749
DOI: 10.1002/advs.202206068 -
Epigenetics Dec 2023DNA methylation, one of the best characterized epigenetic marks in the human genome, plays a pivotal role in gene transcription regulation and other biological processes...
DNA methylation, one of the best characterized epigenetic marks in the human genome, plays a pivotal role in gene transcription regulation and other biological processes in humans. On top of that, the DNA methylome undergoes profound changes in cancer and other disorders. However, large-scale and population-based studies are limited by high costs and the need for considerable expertise in data analysis for whole-genome bisulphite-sequencing methodologies. Following the success of the EPIC DNA methylation microarray, the newly developed Infinium HumanMethylationEPIC version 2.0 (900K EPIC v2) is now available. This new array contains more than 900,000 CpG probes covering the human genome and excluding masked probes from the previous version. The 900K EPIC v2 microarray adds more than 200,000 probes covering extra DNA cis-regulatory regions such as enhancers, super-enhancers and CTCF binding regions. Herein, we have technically and biologically validated the new methylation array to show its high reproducibility and consistency among technical replicates and with DNA extracted from FFPE tissue. In addition, we have hybridized primary normal and tumoural tissues and cancer cell lines from different sources and tested the robustness of the 900K EPIC v2 microarray when analysing the different DNA methylation profiles. The validation highlights the improvements offered by the new array and demonstrates the versatility of this updated tool for characterizing the DNA methylome in human health and disease.
Topics: Humans; DNA Methylation; Epigenome; Reproducibility of Results; Microarray Analysis; Cell Line
PubMed: 36871255
DOI: 10.1080/15592294.2023.2185742 -
Gut Microbes Dec 2023Individuals with nonalcoholic fatty liver disease (NAFLD) have an altered gut microbiota composition. Moreover, hepatic DNA methylation may be altered in the state of...
Individuals with nonalcoholic fatty liver disease (NAFLD) have an altered gut microbiota composition. Moreover, hepatic DNA methylation may be altered in the state of NAFLD. Using a fecal microbiota transplantation (FMT) intervention, we aimed to investigate whether a change in gut microbiota composition relates to altered liver DNA methylation in NAFLD. Moreover, we assessed whether plasma metabolite profiles altered by FMT relate to changes in liver DNA methylation. Twenty-one individuals with NAFLD underwent three 8-weekly vegan allogenic donor ( = 10) or autologous ( = 11) FMTs. We obtained hepatic DNA methylation profiles from paired liver biopsies of study participants before and after FMTs. We applied a multi-omics machine learning approach to identify changes in the gut microbiome, peripheral blood metabolome and liver DNA methylome, and analyzed cross-omics correlations. Vegan allogenic donor FMT compared to autologous FMT induced distinct differential changes in I) gut microbiota profiles, including increased abundance of and potential probiotic ; II) plasma metabolites, including altered levels of phenylacetylcarnitine (PAC) and phenylacetylglutamine (PAG) both from gut-derived phenylacetic acid, and of several choline-derived long-chain acylcholines; and III) hepatic DNA methylation profiles, most importantly in Threonyl-TRNA Synthetase 1 ( and Zinc finger protein 57 (. Multi-omics analysis showed that and __170 positively correlated with both PAC and PAG. negatively correlated with DNA methylation of cg16885113 in . Alterations in gut microbiota composition by FMT caused widespread changes in plasma metabolites (e.g. PAC, PAG, and choline-derived metabolites) and liver DNA methylation profiles in individuals with NAFLD. These results indicate that FMTs might induce metaorganismal pathway changes, from the gut bacteria to the liver.
Topics: Humans; Non-alcoholic Fatty Liver Disease; Fecal Microbiota Transplantation; DNA Methylation; Multiomics; Gastrointestinal Microbiome; Choline
PubMed: 37317027
DOI: 10.1080/19490976.2023.2223330 -
Signal Transduction and Targeted Therapy Aug 2023Major depressive disorder (MDD) is a chronic, generally episodic and debilitating disease that affects an estimated 300 million people worldwide, but its pathogenesis is... (Review)
Review
Major depressive disorder (MDD) is a chronic, generally episodic and debilitating disease that affects an estimated 300 million people worldwide, but its pathogenesis is poorly understood. The heritability estimate of MDD is 30-40%, suggesting that genetics alone do not account for most of the risk of major depression. Another factor known to associate with MDD involves environmental stressors such as childhood adversity and recent life stress. Recent studies have emerged to show that the biological impact of environmental factors in MDD and other stress-related disorders is mediated by a variety of epigenetic modifications. These epigenetic modification alterations contribute to abnormal neuroendocrine responses, neuroplasticity impairment, neurotransmission and neuroglia dysfunction, which are involved in the pathophysiology of MDD. Furthermore, epigenetic marks have been associated with the diagnosis and treatment of MDD. The evaluation of epigenetic modifications holds promise for further understanding of the heterogeneous etiology and complex phenotypes of MDD, and may identify new therapeutic targets. Here, we review preclinical and clinical epigenetic findings, including DNA methylation, histone modification, noncoding RNA, RNA modification, and chromatin remodeling factor in MDD. In addition, we elaborate on the contribution of these epigenetic mechanisms to the pathological trait variability in depression and discuss how such mechanisms can be exploited for therapeutic purposes.
Topics: Humans; Depressive Disorder, Major; Clinical Relevance; Depression; Epigenesis, Genetic; DNA Methylation
PubMed: 37644009
DOI: 10.1038/s41392-023-01519-z -
Genetics in Medicine : Official Journal... Aug 2023HNRNPU haploinsufficiency is associated with developmental and epileptic encephalopathy 54. This neurodevelopmental disorder is characterized by developmental delay,...
PURPOSE
HNRNPU haploinsufficiency is associated with developmental and epileptic encephalopathy 54. This neurodevelopmental disorder is characterized by developmental delay, intellectual disability, speech impairment, and early-onset epilepsy. We performed genome-wide DNA methylation (DNAm) analysis in a cohort of individuals to develop a diagnostic biomarker and gain functional insights into the molecular pathophysiology of HNRNPU-related disorder.
METHODS
DNAm profiles of individuals carrying pathogenic HNRNPU variants, identified through an international multicenter collaboration, were assessed using Infinium Methylation EPIC arrays. Statistical and functional correlation analyses were performed comparing the HNRNPU cohort with 56 previously reported DNAm episignatures.
RESULTS
A robust and reproducible DNAm episignature and global DNAm profile were identified. Correlation analysis identified partial overlap and similarity of the global HNRNPU DNAm profile to several other rare disorders.
CONCLUSION
This study demonstrates new evidence of a specific and sensitive DNAm episignature associated with pathogenic heterozygous HNRNPU variants, establishing its utility as a clinical biomarker for the expansion of the EpiSign diagnostic test.
Topics: Humans; DNA Methylation; Epigenomics; Phenotype; Neurodevelopmental Disorders; Biomarkers
PubMed: 37120726
DOI: 10.1016/j.gim.2023.100871 -
JAMA Network Open Nov 2023The biological processes that underlie the association of neighborhood environment with chronic diseases, such as cancer, remain poorly understood.
IMPORTANCE
The biological processes that underlie the association of neighborhood environment with chronic diseases, such as cancer, remain poorly understood.
OBJECTIVE
To determine whether differences in breast tissue DNA methylation are associated with neighborhood deprivation among Black and White women with breast cancer.
DESIGN, SETTING, AND PARTICIPANTS
This cross-sectional study collected breast tissue from women undergoing surgery for breast cancer between January 1, 1993, and December 31, 2003. Participants were recruited through the University of Maryland Medical Center, with additional collection sites at Baltimore-area hospitals. Data analysis was performed from March 1 through December 1, 2022.
EXPOSURE
Year 2000 census tract-level socioeconomic deprivation measured via neighborhood deprivation index (NDI) as a standardized score, with Black and White race being ascertained through self-report.
MAIN OUTCOME AND MEASURES
The primary outcome was tissue DNA methylation using genome-wide measurements. The secondary outcome was tissue gene expression.
RESULTS
Participants included 185 women with breast cancer (110 Black [59.5%], 75 White [40.5%]). Mean (SD) age at surgery was 56.0 (14.1) years. Neighborhood deprivation was higher for Black women than for White women (Mean [SD] NDI, 2.96 [3.03] for Black women and -0.54 [1.91] for White women; difference, -3.50; 95% CI, -4.22 to -2.79; P < .001). In unstratified analysis, 8 hypomethylated CpG sites were identified as associated with the NDI, including sites in 2 tumor suppressor genes, LRIG1 and WWOX. Moreover, expression of the 2 genes inversely correlated with neighborhood deprivation. In the race-stratified analysis, the negative correlation between the LRIG1 gene body CpG site cg26131019 and the NDI remained significant in Black women. A neighborhood deprivation-associated decrease in gene expression was also observed for LRIG1 and WWOX in tumors from Black women.
CONCLUSIONS AND RELEVANCE
In this study, high neighborhood deprivation was associated with differences in tissue DNA methylation and gene expression among Black women. These findings suggest that continued investment in public health interventions and policy changes at the neighborhood level may help to remedy biological alterations that could make minoritized populations more susceptible to chronic diseases.
Topics: Humans; Female; Middle Aged; Cross-Sectional Studies; DNA Methylation; Breast Neoplasms; Chronic Disease; Genes, Neoplasm
PubMed: 37930698
DOI: 10.1001/jamanetworkopen.2023.41651 -
Genes Nov 2023Infertility affects a significant number of couples worldwide and its incidence is increasing. While assisted reproductive technologies (ART) have revolutionized the... (Review)
Review
Infertility affects a significant number of couples worldwide and its incidence is increasing. While assisted reproductive technologies (ART) have revolutionized the treatment landscape of infertility, a significant number of couples present with an idiopathic cause for their infertility, hindering effective management. Profiling the genome and transcriptome of infertile men and women has revealed abnormal gene expression. Epigenetic modifications, which comprise dynamic processes that can transduce environmental signals into gene expression changes, may explain these findings. Indeed, aberrant DNA methylation has been widely characterized as a cause of abnormal sperm and oocyte gene expression with potentially deleterious consequences on fertilization and pregnancy outcomes. This review aims to provide a concise overview of male and female infertility through the lens of DNA methylation alterations.
Topics: Pregnancy; Male; Humans; Female; DNA Methylation; Semen; Infertility; Epigenesis, Genetic; Reproductive Techniques, Assisted
PubMed: 38136954
DOI: 10.3390/genes14122132 -
Environment International Nov 2023Lead is a common environmental heavy metal contaminant. Humans are highly susceptible to lead accumulation in the body, which causes nervous system damage and leads to a... (Review)
Review
Lead is a common environmental heavy metal contaminant. Humans are highly susceptible to lead accumulation in the body, which causes nervous system damage and leads to a variety of nervous system diseases, such as Alzheimer's disease, Parkinson's disease, and autism spectrum disorder. Recent research has focused on the mechanisms of lead-induced neurotoxicity at multiple levels, including DNA methylation, histone modifications, and non-coding RNAs, which are involved in various lead-induced nervous system diseases. We reviewed the latest articles and summarised the emerging roles of DNA methylation, histone modification, and non-coding RNAs in lead-induced neurotoxicity. Our summary provides a theoretical basis and directions for future research on the prevention, diagnosis, and treatment of lead-induced neurological diseases.
Topics: Humans; Autism Spectrum Disorder; Lead; Epigenesis, Genetic; DNA Methylation; Nervous System Diseases
PubMed: 37864902
DOI: 10.1016/j.envint.2023.108253 -
Hypertension (Dallas, Tex. : 1979) Aug 2023
Topics: DNA Methylation; Epigenesis, Genetic; Epigenomics; Humans
PubMed: 37470774
DOI: 10.1161/HYPERTENSIONAHA.123.21197