scholarly journals DNA methylation in Arabidopsis has a genetic basis and shows evidence of local adaptation

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Manu J Dubin ◽  
Pei Zhang ◽  
Dazhe Meng ◽  
Marie-Stanislas Remigereau ◽  
Edward J Osborne ◽  
...  

Epigenome modulation potentially provides a mechanism for organisms to adapt, within and between generations. However, neither the extent to which this occurs, nor the mechanisms involved are known. Here we investigate DNA methylation variation in Swedish Arabidopsis thaliana accessions grown at two different temperatures. Environmental effects were limited to transposons, where CHH methylation was found to increase with temperature. Genome-wide association studies (GWAS) revealed that the extensive CHH methylation variation was strongly associated with genetic variants in both cis and trans, including a major trans-association close to the DNA methyltransferase CMT2. Unlike CHH methylation, CpG gene body methylation (GBM) was not affected by growth temperature, but was instead correlated with the latitude of origin. Accessions from colder regions had higher levels of GBM for a significant fraction of the genome, and this was associated with increased transcription for the genes affected. GWAS revealed that this effect was largely due to trans-acting loci, many of which showed evidence of local adaptation.

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Daniel L. McCartney ◽  
Josine L. Min ◽  
Rebecca C. Richmond ◽  
Ake T. Lu ◽  
Maria K. Sobczyk ◽  
...  

Abstract Background Biological aging estimators derived from DNA methylation data are heritable and correlate with morbidity and mortality. Consequently, identification of genetic and environmental contributors to the variation in these measures in populations has become a major goal in the field. Results Leveraging DNA methylation and SNP data from more than 40,000 individuals, we identify 137 genome-wide significant loci, of which 113 are novel, from genome-wide association study (GWAS) meta-analyses of four epigenetic clocks and epigenetic surrogate markers for granulocyte proportions and plasminogen activator inhibitor 1 levels, respectively. We find evidence for shared genetic loci associated with the Horvath clock and expression of transcripts encoding genes linked to lipid metabolism and immune function. Notably, these loci are independent of those reported to regulate DNA methylation levels at constituent clock CpGs. A polygenic score for GrimAge acceleration showed strong associations with adiposity-related traits, educational attainment, parental longevity, and C-reactive protein levels. Conclusion This study illuminates the genetic architecture underlying epigenetic aging and its shared genetic contributions with lifestyle factors and longevity.


2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Tianxiao Huan ◽  
Roby Joehanes ◽  
Ci Song ◽  
Fen Peng ◽  
Yichen Guo ◽  
...  

Abstract Identifying methylation quantitative trait loci (meQTLs) and integrating them with disease-associated variants from genome-wide association studies (GWAS) may illuminate functional mechanisms underlying genetic variant-disease associations. Here, we perform GWAS of >415 thousand CpG methylation sites in whole blood from 4170 individuals and map 4.7 million cis- and 630 thousand trans-meQTL variants targeting >120 thousand CpGs. Independent replication is performed in 1347 participants from two studies. By linking cis-meQTL variants with GWAS results for cardiovascular disease (CVD) traits, we identify 92 putatively causal CpGs for CVD traits by Mendelian randomization analysis. Further integrating gene expression data reveals evidence of cis CpG-transcript pairs causally linked to CVD. In addition, we identify 22 trans-meQTL hotspots each targeting more than 30 CpGs and find that trans-meQTL hotspots appear to act in cis on expression of nearby transcriptional regulatory genes. Our findings provide a powerful meQTL resource and shed light on DNA methylation involvement in human diseases.


2021 ◽  
pp. 135245852110044
Author(s):  
Yuan Zhou ◽  
Gabriel Cuellar-Partida ◽  
Steve Simpson Yap ◽  
Xin Lin ◽  
Suzi Claflin ◽  
...  

Background: Genome-wide association studies (GWAS) have succeeded in identifying over 200 susceptibility loci for multiple sclerosis (MS). However, the potential functional variants and the mechanisms by which these loci affect MS risk remain largely unexplained. Objectives: We used summary data-based Mendelian randomisation to prioritise risk genes and infer potential biological mechanisms for MS risk loci. Methods: The data used consisted of DNA methylation ( n = 1980) QTL (mQTL) and gene expression ( n = 31,684) QTL (eQTL) derived from whole blood as well as MS GWAS summary statistics (14,802 cases, 26,703 controls). The findings were further evaluated using data derived from independent brain mQTL ( n = 1160) and eQTL ( n = 1194). Results: In whole blood, we identified two independent genomic loci (lincRNA: RP11-326C3.13 and TNFSF14) with consistent genome-wide significant pleiotropic associations across different omics layers. In brain tissue, a similar effect for the RP11-326C3.13 locus was observed but not for TNFSF14, indicating a potential tissue-specific effect for the TNFSF14 locus. Conclusion: We provide in silico evidence for the putative biological mechanisms by which the identified DNA methylation sites and target genes are functionally relevant to MS development in different tissues. Future research targeting these genes and DNA methylation sites will determine their roles in the pathophysiology of MS.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Adrienne Tin ◽  
Pascal Schlosser ◽  
Pamela R. Matias-Garcia ◽  
Chris H. L. Thio ◽  
Roby Joehanes ◽  
...  

AbstractElevated serum urate levels, a complex trait and major risk factor for incident gout, are correlated with cardiometabolic traits via incompletely understood mechanisms. DNA methylation in whole blood captures genetic and environmental influences and is assessed in transethnic meta-analysis of epigenome-wide association studies (EWAS) of serum urate (discovery, n = 12,474, replication, n = 5522). The 100 replicated, epigenome-wide significant (p < 1.1E–7) CpGs explain 11.6% of the serum urate variance. At SLC2A9, the serum urate locus with the largest effect in genome-wide association studies (GWAS), five CpGs are associated with SLC2A9 gene expression. Four CpGs at SLC2A9 have significant causal effects on serum urate levels and/or gout, and two of these partly mediate the effects of urate-associated GWAS variants. In other genes, including SLC7A11 and PHGDH, 17 urate-associated CpGs are associated with conditions defining metabolic syndrome, suggesting that these CpGs may represent a blood DNA methylation signature of cardiometabolic risk factors. This study demonstrates that EWAS can provide new insights into GWAS loci and the correlation of serum urate with other complex traits.


Author(s):  
Abhijeet Roy

Type 2 Diabetes is one of the major public health issues and a complex metabolic disorder strongly associated with genetic predisposition influenced by environmental factors and epigenetic regulation. This review paper illustrated the role of epigenetics in the pathogenesis, progression, and detection of Type 2 Diabetes. A review study was performed for the articles published in English from 2000-2019 using Pub Med, and Google Scholar databases. Main underlining mechanisms of Type 2 Diabetes were identified; insulin resistance in the peripheral tissue, and disintegrate insulin secretion. Genome Wide Association Studies suggested that epigenetic regulation such as DNA methylation, Histone modification, Non-coding RNA, microRNA is strongly related with the development of Type 2 Diabetes. Altered DNA methylation patterns in pancreatic islets, skeletal muscle, adipose tissue, from diabetic subjects compare to normal subjects was also found. Other risk factors like; obesity, age, gender, impaired glucose tolerance, periconception and intrauterine environment may also have been linked with the possibilities of epigenetic changes. Epigenetics plays a crucial role by modifying the gene expression and establish a relationship between the environment and genetic factors. Understanding the epigenetic mechanisms contributing to the development of Type 2 Diabetes is still limited.


2019 ◽  
Author(s):  
Eriko Sasaki ◽  
Taiji Kawakatsu ◽  
Joseph Ecker ◽  
Magnus Nordborg

AbstractDNA cytosine methylation is an epigenetic mark associated with silencing of transposable elements (TEs) and heterochromatin formation. In plants, it occurs in three sequence contexts: CG, CHG, and CHH (where H is A, T, or C). The latter does not allow direct inheritance of methylation during DNA replication due to lack of symmetry, and methylation must therefore be re-established every cell generation. Genome-wide association studies (GWAS) have previously shown that CMT2 and NRPE1 are major determinants of genome-wide patterns of TE CHH-methylation. Here we instead focus on CHH-methylation of individual TEs and TE-families, allowing us to identify the pathways involved in CHH-methylation simply from natural variation and confirm the associations by comparing them with mutant phenotypes. Methylation at TEs targeted by the RNA-directed DNA methylation (RdDM) pathway is unaffected by CMT2 variation, but is strongly affected by variation at NRPE1, which is largely responsible for the longitudinal cline in this phenotype. In contrast, CMT2-targeted TEs are affected by both loci, which jointly explain 7.3% of the phenotypic variation (13.2% of total genetic effects). There is no longitudinal pattern for this phenotype, however, because the geographic patterns appear to compensate for each other in a pattern suggestive of stabilizing selection.Author SummaryDNA methylation is a major component of transposon silencing, and essential for genomic integrity. Recent studies revealed large-scale geographic variation as well as the existence of major trans-acting polymorphisms that partly explained this variation. In this study, we re-analyze previously published data (The 1001 Epigenomes), focusing on de novo DNA methylation patterns of individual TEs and TE families rather than on genome-wide averages (as was done in previous studies). GWAS of the patterns reveals the underlying regulatory networks, and allowed us to comprehensively characterize trans-regulation of de novo DNA methylation and its role in the striking geographic pattern for this phenotype.


2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Yuan-Xiang Shi ◽  
De-Qiao Sheng ◽  
Lin Cheng ◽  
Xin-Yu Song

Lung cancer is the leading cause of cancer-related mortality worldwide. Tumorigenesis involves a multistep process resulting from the interactions of genetic, epigenetic, and environmental factors. Genome-wide association studies and sequencing studies have identified many epigenetic alterations associated with the development of lung cancer. Epigenetic mechanisms, mainly including DNA methylation, histone modification, and noncoding RNAs (ncRNAs), are heritable and reversible modifications that are involved in some important biological processes and affect cancer hallmarks. We summarize the major epigenetic modifications in lung cancer, focusing on DNA methylation and ncRNAs, their roles in tumorigenesis, and their effects on key signaling pathways. In addition, we describe the clinical application of epigenetic biomarkers in the early diagnosis, prognosis prediction, and oncotherapy of lung cancer. Understanding the epigenetic regulation mechanism of lung cancer can provide a new explanation for tumorigenesis and a new target for the precise treatment of lung cancer.


2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Mark Ziemann ◽  
KN Harikrishnan ◽  
Ishant Khurana ◽  
Antony Kaspi ◽  
Samuel T Keating ◽  
...  

Abstract Despite recent progress in screening for genetic causes of cardiovascular disease using genome-wide association studies, identifying causative polymorphisms has not met initial expectations. This has led to interest in exploring the contribution of non-genetic factors in disease etiology. Elevated plasma homocysteine is an independent risk factor for cardiovascular disease but the mechanism for increased risk remains poorly understood. This study evaluates the clinical applicability of screening for genome-wide CpG methylation differences using methyl-CpG binding domain (MBD) protein-enriched genome sequencing (MBD-seq). Peripheral blood genomic DNA methylation in 8 Singaporean-Chinese ischemic stroke patients (4 male, 4 female) was profiled. Differential methylation of genes implicated in hyperhomocysteinemia was observed in males correlating with homocysteine; namely CBS (cystathionine-beta-synthase) and MTHFR (methylenetetrahydrofolate reductase). In females, hypomethylation of the LDLR (low density lipoprotein receptor) and CELSR1 (cadherin, EGF LAG seven-pass G-type receptor 1) genes were observed in the hypertensive group (2 normal and 2 hypertensive individuals). While the number of clinical samples analysed is small, the findings of this evaluation suggest that MBD-seq is a suitable and sufficiently sensitive technology to determine methylation variability. The results presented warrant an expanded case-control study to determine the pathophysiological implications of DNA methylation for hyper-homocysteinemia.


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