Epigenetic and transcriptomic characterization of pure adipocyte fractions from obese pigs identifies candidate pathways controlling metabolism
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ABSTRACT: Reprogramming of adipocyte function in obesity is implicated in metabolic disorders like type 2 diabetes. Here, we used the pig, an animal model sharing many physiological and pathophysiological similarities with humans, to perform in depth epigenomic and transcriptomic characterization of pure adipocyte fractions. Using a combined DNA methylation capture sequencing and Reduced Representation bisulfite sequencing (RRBS) strategy, we identified 2479 differentially methylated regions (DMRs) located at close proximity to-, or within genes. By sequencing of the transcriptome from the same adipocyte cells, we identified 276 differentially expressed transcripts with at least one or more DMRs. These transcripts were over-represented in gene pathways related to MAPK, insulin and adipocytokine signaling. Using a candidate gene approach, we further characterized 13 genes potentially regulated by DNA methylation and identified putative transcription factor binding sites that could be affected by the differential methylation in obesity. Our data constitute a valuable resource for further investigations aiming to delineate the epigenetic etiology of metabolic disorders.
Project description:Folic acid (FA) supplementation may protect from obesity and insulin resistance, the effects and mechanism of FA on chronic high-fat-diet-induced obesity-related metabolic disorders are not well elucidated. We adopted a genome-wide approach to directly examine whether FA supplementation affects the DNA methylation profile of mouse adipose tissue and identify the functional consequences of these changes. Mice were fed a high-fat diet (HFD), normal diet (ND) or an HFD supplemented with folic acid (20 μg/ml in drinking water) for 10 weeks, epididymal fat was harvested, and genome-wide DNA methylation analyses were performed using methylated DNA immunoprecipitation sequencing (MeDIP-seq). Mice exposed to the HFD expanded their adipose mass, which was accompanied by a significant increase in circulating glucose and insulin levels. FA supplementation reduced the fat mass and serum glucose levels and improved insulin resistance in HFD-fed mice. MeDIP-seq revealed distribution of differentially methylated regions (DMRs) throughout the adipocyte genome, with more hypermethylated regions in HFD mice. Methylome profiling identified DMRs associated with 3787 annotated genes from HFD mice in response to FA supplementation. Pathway analyses showed novel DNA methylation changes in adipose genes associated with insulin secretion, pancreatic secretion and type 2 diabetes. The differential DNA methylation corresponded to changes in the adipose tissue gene expression of Adcy3 and Rapgef4 in mice exposed to a diet containing FA. FA supplementation improved insulin resistance, decreased the fat mass, and induced DNA methylation and gene expression changes in genes associated with obesity and insulin secretion in obese mice fed a HFD.
Project description:This study examines the transgenerational adipocyte (fat cell) epigenetic alterations in F3 generation obese and lean rats ancestrally exposed to DDT and atrazine. Adipocytes were isolated from the gonadal fat pad of F3 generation 1-year old rats ancestrally exposed to DDT, atrazine, or vehicle control in order to obtain adipocyte DNA for DNA methylation analysis. Observations indicate that there were differential DNA methylated regions (DMRs) in the adipocytes with the lean or obese phenotypes compared to control normal (non-obese or lean) populations. Interestingly, there were epigenetic changes that were distinct when comparing the lean and obese DMRs between the control and exposure lineage groups. DMR gene associations were identified which included common set of genes previously shown to associate with adipocyte pathology. The comparison of epigenetic alterations indicated that there were substantial overlaps between the different treatment lineage groups for both the lean and obese phenotypes. Novel correlated genes and gene pathways associated with DNA methylation were identified, and may aid in the discovery of potential therapeutic targets for metabolic diseases such as obesity.
Project description:Maternal obesity during pregnancy is associated with neurodevelopmental disorder (NDD) risk. We utilized integrative multi-omics to examine maternal obesity effects on offspring neurodevelopment in rhesus macaques by comparison to lean controls and two interventions. Differentially methylated regions (DMRs) from longitudinal maternal blood-derived cell-free fetal DNA (cffDNA) significantly overlapped with DMRs from infant brain. The DMRs were enriched for neurodevelopmental functions, methylation-sensitive developmental transcription factor motifs, and human NDD DMRs identified from brain and placenta. Brain and cffDNA methylation levels from a large region overlapping mir-663 correlated with maternal obesity, metabolic and immune markers, and infant behavior. A DUX4 hippocampal co-methylation network correlated with maternal obesity, infant behavior, infant hippocampal lipidomic and metabolomic profiles, and maternal blood measurements of DUX4 cffDNA methylation, cytokines, and metabolites. We conclude that in this model, maternal obesity was associated with changes in the infant brain and behavior, and these differences were detectable in pregnancy through integrative analyses of cffDNA methylation with immune and metabolic factors.
Project description:DNA methylation variations are prevalent in human obesity but evidence of a causative role in disease pathogenesis is limited. Here, we combine epigenome-wide association and integrative genomics to investigate the impact of adipocyte DNA methylation variations in human obesity. We discover extensive DNA methylation changes that are robustly associated with obesity (N=190 samples, 691 loci in subcutaneous and 173 loci in visceral adipocytes, P<1x10-7). We connect obesity-associated methylation variations to transcriptomic changes at >500 target genes, and identify putative methylation-transcription factor interactions. Through Mendelian Randomisation, we infer causal effects of methylation on obesity and obesity-induced metabolic disturbances at 59 independent loci. Targeted methylation sequencing, CRISPR-activation and gene silencing in adipocytes, further identifies regional methylation variations, underlying regulatory elements and novel cellular metabolic effects. Our results indicate DNA methylation is an important determinant of human obesity and its metabolic complications, and reveal mechanisms through which altered methylation may impact adipocyte functions.
Project description:DNA methylation variations are prevalent in human obesity but evidence of a causative role in disease pathogenesis is limited. Here, we combine epigenome-wide association and integrative genomics to investigate the impact of adipocyte DNA methylation variations in human obesity. We discover extensive DNA methylation changes that are robustly associated with obesity (N=190 samples, 691 loci in subcutaneous and 173 loci in visceral adipocytes, P<1x10-7). We connect obesity-associated methylation variations to transcriptomic changes at >500 target genes, and identify putative methylation-transcription factor interactions. Through Mendelian Randomisation, we infer causal effects of methylation on obesity and obesity-induced metabolic disturbances at 59 independent loci. Targeted methylation sequencing, CRISPR-activation and gene silencing in adipocytes, further identifies regional methylation variations, underlying regulatory elements and novel cellular metabolic effects. Our results indicate DNA methylation is an important determinant of human obesity and its metabolic complications, and reveal mechanisms through which altered methylation may impact adipocyte functions.
Project description:Obesity is linked to the development of metabolic disorders. Expansion of white adipose tissue (WAT) from hypertrophy of pre-existing adipocytes and/or differentiation of precursors into new mature adipocytes contributes to obesity. We found that Nck2 expression is largely restricted to WAT, raising the hypothesis that it may play a unique function in that tissue. Using mice lacking Nck2, we found that Nck2 regulates adipocyte hypertrophy thus contributing to increased adiposity and progressive glucose intolerance, insulin resistance and hepatic steatosis. These findings were recapitulated in humans such that Nck2 expression in omental WAT was inversely correlated with the degree of obesity. Mechanistically, Nck2 deficiency promoted the induction of an adipocyte differentiation program and signaling by the PERK-eIF2α-ATF4 pathway in agreement with a role for the unfolded protein response in adipogenesis. These findings uncover Nck2 as a novel regulator of adipogenesis and that perturbation in its functionality contributes to adiposity-related metabolic disorders. Differential gene expression profile between epididymal white adipose tissue of Nck2-/- and Nck2+/+ mice by RNA sequencing (Illumina HiSEq 2000)
Project description:It is evident that epigenetic factors, especially DNA methylation, play essential roles in obesity development. To learn systematic association of DNA methylation to obesity, we used pig as a model, and sampled eight diverse adipose tissues and two distinct skeletal muscle tissues from three pig breeds with distinguished fat levels: the lean Landrace, the fatty Rongchang, and the feral Tibetan pig. We sequenced 180 methylated DNA immunoprecipitation (MeDIP) libraries, generated 1,381 Gbp sequence data, and provided a genome-wide DNA methylation map for pig adipose and muscle studies. The analysis showed global similarities and differences between breeds, genders and tissues, and identified the differentially methylated regions (DMRs) that are preferentially located in intermediate CpG promoters and CpG island shores. The DMRs in promoters are highly associated to obesity development. We also analyzed methylation and regulation of the known obesity-related genes and predicted novel candidate genes. The comprehensive map here provides a solid base for exploring epigenetic mechanisms of adipose deposition and muscle growth. We collected eight diverse adipose tissues and two phenotypically distinct skeletal muscle tissues from three well-defined pig models with distinct fat rates, and studied genome-wide DNA methylation differences among breeds, males and females, and tissues.
Project description:Background: Late gestational sleep fragmentation (LG-SF) is one of the major perturbations associated with sleep apnea and other sleep disorders during pregnancy. Objectives: To investigate the effects of late LG-SF on the epigenome of visceral white adipose tissue (VWAT) in the offspring. Methods: Time-pregnant mice were exposed to LG-SF or control sleep (LG-SC) conditions during the last 6 days of gestation. We performed large-scale DNA methylation analyses using MeDIP coupled to microarrays (MeDIP-chip) in VWAT of 24-week-old LG-SF and LG-SC offspring (n=8 mice/group). Univariate multiple-testing adjusted statistical analyses were applied to identify differentially methylated regions (DMRs) between the groups. DMRs were mapped to their corresponding genes, and tested for potential overlaps with biological pathways and gene networks. Results: We detected 2148 DMRs between LG-SF and LG-SC groups (p< 0.0001, MAT algorithm). A large proportion of the DMR-associated genes have reported functions that are altered in obesity and metabolic syndrome. Overrepresented pathways and gene networks were related to metabolic regulation and inflammatory response. Conclusions: Our findings show a major role for epigenomic regulation of pathways associated to metabolic processes and inflammatory response in VWAT. Furthermore, LG-SF-induced epigenetic alterations appear to increase the susceptibility to obesity and metabolic syndrome in the offspring. 16 mouse VWAT samples were analyzed by MeDIP coupled to microarray analysis: Offspring of mothers exposed to late-gestational sleep fragmentation (n=8, LG-SF group) and offspring of mothers mouse exposed to normal sleep conditions (n=8, LG-SC group)
Project description:Different human adipose tissue depots may have functional differences. Subcutaneous human adipose tissue has been extensively studied, but less is known about other depots. Perithyroid (PT) adipose tissue contains not only white adipocytes but also brown adipocytes. The aim of this study was to compare the expression of brown adipocyte containing perithyroid adipose tissue with s.c. adipose tissue.role in the development of obesity. Expression profiling of adipose tissue may give insights into mechanisms contributing to obesity and obesity-related disorders. Expression analysis of paired biopsies from s.c and perithyriod (PT) adipose tissue from nine subjects undergoing surgery in the thyroid region.
Project description:Parental imprinting is an epigenetic phenomenon by which genes are expressed in a monoallelic fashion, according to their parent-of-origin. DNA methylation is considered the hallmark mechanism regulating parental imprinting. To identify imprinted differentially methylated regions (DMRs), we compared the DNA methylation status between multiple normal and parthenogenetic human pluripotent stem cells (PSCs) by performing reduced representation bisulfite sequencing. Our analysis identified over twenty previously unknown imprinted DMRs in addition to the known DMRs. These include DMRs in loci associated with human disorders, and a class of intergenic DMRs that do not seem to be related to gene expression. Furthermore, the study showed some DMRs to be unstable, liable to differentiation or reprogramming. A comprehensive comparison between mouse and human DMRs identified almost half of the imprinted DMRs to be species-specific. Taken together our data map novel DMRs in the human genome, their evolutionary conservation, and relation to gene expression. RRBS profiles were generated from 6 parthenogenetic iPSC lines (hiPS A11, hiPS A20, hIPS A26, hiPS B34, hiPS B36, hiPS B41) and fibroblasts from the 2 parents whose ovarian teratomas were used to derive the iPSC lines, for a total of 8 samples.