Project description:The aim of this study was to identify new genes controlling insulin sensitivity in adipocytes from obese women with either insulin-resistant (OIR) or -sensitive (OIS) adipocytes. 432 genes were differentially expressed between the OIR and OIS group (FDR <5%). These genes are enriched in pathways related to glucose and amino acid metabolism, cellular respiration, and insulin signaling. Two IR-associated genes, KLF15 and SLC25A10, were selected for functional evaluation.
Project description:The aim of this study was to identify new genes controlling insulin sensitivity in adipocytes from obese women with either insulin-resistant (OIR) or -sensitive (OIS) adipocytes. 432 genes were differentially expressed between the OIR and OIS group (FDR <5%). These genes are enriched in pathways related to glucose and amino acid metabolism, cellular respiration, and insulin signaling, and include SLC2A4, AKT2, as well as enzymes in the mitochondria respiratory chain. Two IR-associated genes, KLF15 and SLC25A10, were selected for functional evaluation.
Project description:The association between central obesity and insulin resistance reflects the properties of visceral adipose tissue. Our aim was to gain further insight into this association by analysing the lipid composition of subcutaneous and omental adipose tissue in obese women with and without insulin resistance. Subcutaneous and omental adipose tissue and serum were obtained from 29 obese nondiabetic women, 13 of whom were hyperinsulinemic. Histology, and lipid and gene profiling were performed. In omental adipose tissue of obese, insulin-resistant women, adipocyte hypertrophy and macrophage infiltration were accompanied by an increase in GM3 ganglioside and its synthesis enzyme ST3GAL5; in addition, phosphatidylethanolamine (PE) lipids were increased and their degradation enzyme, PEMT, decreased. ST3GAL5 was expressed predominantly in adipose stromovascular cells and PEMT in adipocytes. Insulin resistance was also associated with an increase in PE lipids in serum. Total RNA was isolated and up to 400 ng of total RNA per sample was labelled and hybridized to Illumina HumanHT-12_V4 expression BeadChip platform. Paired subcutaneous and omental samples from 6 women were analysed.
Project description:The association between central obesity and insulin resistance reflects the properties of visceral adipose tissue. Our aim was to gain further insight into this association by analysing the lipid composition of subcutaneous and omental adipose tissue in obese women with and without insulin resistance. Subcutaneous and omental adipose tissue and serum were obtained from 29 obese nondiabetic women, 13 of whom were hyperinsulinemic. Histology, and lipid and gene profiling were performed. In omental adipose tissue of obese, insulin-resistant women, adipocyte hypertrophy and macrophage infiltration were accompanied by an increase in GM3 ganglioside and its synthesis enzyme ST3GAL5; in addition, phosphatidylethanolamine (PE) lipids were increased and their degradation enzyme, PEMT, decreased. ST3GAL5 was expressed predominantly in adipose stromovascular cells and PEMT in adipocytes. Insulin resistance was also associated with an increase in PE lipids in serum.
Project description:Purpose: To determine how STAT1 activity in white adipocytes affects insulin sensitivity. Methods: Adipocyte specific (ADIPOQ-Cre) STAT1 fl/fl mice (STAT1 fKO) and littermate controls (STAT1 fl/fl) were placed on 60% HFD for 18 weeks, followed by metabolic phenoptying and tissue harvest for RNA-seq Results: STAT1 expression in WAT inversely correlated with fasting plasma glucose in both obese mice and humans. Metabolomic and gene expression profiling established STAT1 deletion in adipocytes (STAT1 fKO) enhanced mitochondrial function and accelerated TCA cycle flux coupled with subcutaneous WAT hyperplasia. STAT1 fKO reduced WAT inflammation, but insulin resistance persisted in obese mice. Rather, elimination of type I cytokine interferon gamma (IFNg) activity enhanced insulin sensitivity in diet-induced obesity. Conclusions: Our findings reveal a permissive mechanism that bridges WAT inflammation to whole-body insulin sensitivity.
Project description:Insulin resistance is a common metabolic abnormality in women with PCOS and leads to an elevated risk of type 2 diabetes. Studies have shown that thiazolidinediones (TZD) improve metabolic disturbances in PCOS patients. We hypothesized that the effect of TZD in PCOS is in part mediated by changes in the transcriptional profile of muscle favoring insulin sensitivity. Using Affymetrix microarrays, we examined the effect of pioglitazone (30 mg/day for 16 weeks) on gene expression in skeletal muscle of 10 obese women with PCOS metabolically characterized by a euglycemic-hyperinsulinemic clamp. Moreover, we explored gene expression changes between these PCOS patients before treatment and 13 healthy control women. Treatment with pioglitazone improved insulin-stimulated total, oxidative and non-oxidative glucose metabolism, and reduced fasting serum insulin (all p < 0.05). Global pathway analysis using Gene Map Annotator and Pathway Profiler (GenMAPP 2.1) and Gene Set Enrichment Analysis (GSEA 2.0.1) revealed a significant upregulation of genes involved in mitochondrial oxidative phosphorylation (OXPHOS), ribosomal proteins, mRNA processing reactome, translation factors, and proteasome complexes in PCOS patients after pioglitazone therapy. Quantitative real-time PCR suggested that upregulation of OXPHOS genes was mediated by an increase in PGC-1M-NM-1 expression (p < 0.05). Expression of genes involved in ribosomal proteins and OXPHOS was down-regulated in PCOS patients before treatment compared to matched healthy women using GenMAPP 2.1 and GSEA 2.1. These data indicate that pioglitazone therapy restores insulin sensitivity in part by a coordinated upregulation of genes involved in mitochondrial oxidative metabolism and protein biosynthesis in skeletal muscle of PCOS. These transcriptional effects of pioglitazone therapy may contribute to prevent the onset of type 2 diabetes in these women. Experiment Overall Design: Ten obese women of reproductive age with PCOS participated in the study to test the effect of pioglitazone therapy (data set 1). To test if pioglitazone ameliorate existing defects in PCOS patients, the expression profile of the 10 PCOS patients before treatment were compared to the same cohort of 13 control subjects (data set 2).
Project description:Maternal obesity in pregnancy is associated with increased birth-weight, obesity and premature mortality in adult offspring. The Effect of Metformin on Maternal and Fetal Outcomes in Pregnant Obese Women (EMPOWaR) trial was a randomised, double-blind, placebo-controlled trial carried out to determine whether exposure to Metformin would affect the offspring birth-weight centile. Obese women exposed to Metformin had increased insulin sensitivity at 36 weeks of pregnancy, but there were no differences in offspring birthweight. We obtained the placentas from these women to determine whether there were differences in expression of genes regulating fetal growth and metabolism. In a complementary study we investigated DNA methylation in the same samples.
Project description:Background Obesity is associated with changes in fat cell gene expression and metabolism. What drives these changes is not well understood. We aimed to explore fat cell epigenetics, i.e., DNA methylation, as one mediator of gene regulation, in obese women. The global DNA methylome for abdominal subcutaneous fat cells was compared between 15 obese case (BMI 41.4 ± 4.4 kg/m 2 , mean ± SD) and 14 never-obese control women (BMI 25.2 ± 2.5 kg/m 2 ). Global array-based transcriptome analysis was analyzed for subcutaneous white adipose tissue (WAT) from 11 obese and 9 never-obese women. Limma was used for statistical analysis. Results We identified 5529 differentially methylated DNA sites (DMS) for 2223 differentially expressed genes between obese cases and never-obese controls (false discovery rate <5 %). The 5529 DMS displayed a median difference in beta value of 0.09 (range 0.01 to 0.40) between groups. DMS were under-represented in CpG islands and in promoter regions, and over-represented in open sea-regions and gene bodies. The 2223 differentially expressed genes with DMS were over-represented in key fat cell pathways: 31 of 130 (25 %) genes linked to “adipogenesis” (adjusted P = 1.66 × 10 −11 ), 31 of 163 (19 %) genes linked to “insulin signaling” (adjusted P = 1.91 × 10 −9 ), and 18 of 67 (27 %) of genes linked to “lipolysis” (P = 6.1 × 10 −5 ). In most cases, gene expression and DMS displayed reciprocal changes in obese women. Furthermore, among 99 candidate genes in genetic loci associated with body fat distribution in genome-wide association studies (GWAS); 22 genes displayed differential expression accompanied by DMS in obese versus never-obese women (P = 0.0002), supporting the notion that a significant proportion of gene loci linked to fat distribution are epigenetically regulated. Conclusions Subcutaneous WAT from obese women is characterized by congruent changes in DNA methylation and expression of genes linked to generation, distribution, and metabolic function of fat cells. These alterations may contribute to obesity-associated metabolic disturbances such as insulin resistance in women. The global DNA methylome in abdominal subcutaneous fat cells was compared between 15 obese cases (BMI 41.4±4.4 kg/m2, mean ± SD) and 14 never-obese control women (BMI 25.2±2.5 kg/m2).