Project description:Domestic broiler chickens rapidly accumulate adipose tissue due to intensive genetic selection for rapid growth and are naturally hyperglycemic and insulin resistant, making them an attractive addition to the suite of rodent models used for studies of obesity and type 2 diabetes in humans. Furthermore, chicken adipose tissue is considered as poorly sensitive to insulin and lipolysis is under glucagon control. Excessive fat accumulation is also an economic and environmental concern for the broiler industry due to the loss of feed efficiency and excessive nitrogen wasting, as well as a negative trait for consumers who are increasingly conscious of dietary fat intake. Understanding the control of avian adipose tissue metabolism would both enhance the utility of chicken as a model organism for human obesity and insulin resistance and highlight new approaches to reduce fat deposition in commercial chickens. In the present study we simultaneously characterized the effects of a short term (5 hours) fast or neutralization of insulin action (5 hours) on adipose tissue of young (16-17 day-old), fed commercial broiler chickens.
Project description:5 arrays from obese insulin-resistant and lean insulin-sensitive females adipose tissue at fasting and after 3h hyperinsulinemia 5 arrays from obese insulin-resistant and lean insulin-sensitive females adipose tissue at fasting and after 3h hyperinsulinemia FIR x 5, FIS x 5, HIR x 5, HIS x 5 F=fasting, H=hyperinsulinemia, IR=Insulin-resistant, IS=Insulin-sensitive (FIR, FIS, HIR, HIS)
Project description:Little is known about the impact of fasting on gene regulation in human adipose tissue. Accordingly, the objective of this study was to investigate the effects of fasting on adipose tissue gene expression in humans. To that end, subcutaneous adipose tissue biopsies were collected from volunteers 2h and 26h after consumption of a standardized meal. For comparison, epididymal adipose tissue was collected from C57Bl/6J mice after a 16h fast and in the ab-libitum fed state. Transcriptome analysis was carried out using Affymetrix microarrays. We found that, 1) fasting downregulated numerous metabolic pathways in human adipose tissue, including triglyceride and fatty acid synthesis, glycolysis and glycogen synthesis, TCA cycle, oxidative phosphorylation, mitochondrial translation, and insulin signaling; 2) fasting downregulated genes involved in proteasomal degradation in human adipose tissue; 3) fasting had much less pronounced effects on the adipose tissue transcriptome in humans than mi ce; 4) although major overlap in fasting-induced gene regulation was observed between human and mouse adipose tissue, many genes were differentially regulated in the two species, including genes involved in insulin signaling (PRKAG2, PFKFB3), PPAR signaling (PPARG, ACSL1, HMGCS2, SLC22A5, ACOT1), glycogen metabolism (PCK1, PYGB), and lipid droplets (PLIN1, PNPLA2, CIDEA, CIDEC). In conclusion, although numerous genes and pathways are regulated similarly by fasting in human and mouse adipose tissue, many genes show very distinct responses to fasting in humans and mice. Our data provide a useful resource to study adipose tissue function during fasting.
Project description:Little is known about the impact of fasting on gene regulation in human adipose tissue. Accordingly, the objective of this study was to investigate the effects of fasting on adipose tissue gene expression in humans. To that end, subcutaneous adipose tissue biopsies were collected from volunteers 2h and 26h after consumption of a standardized meal. For comparison, epididymal adipose tissue was collected from C57Bl/6J mice after a 16h fast and in the ab-libitum fed state. Transcriptome analysis was carried out using Affymetrix microarrays. We found that, 1) fasting downregulated numerous metabolic pathways in human adipose tissue, including triglyceride and fatty acid synthesis, glycolysis and glycogen synthesis, TCA cycle, oxidative phosphorylation, mitochondrial translation, and insulin signaling; 2) fasting downregulated genes involved in proteasomal degradation in human adipose tissue; 3) fasting had much less pronounced effects on the adipose tissue transcriptome in humans than mi ce; 4) although major overlap in fasting-induced gene regulation was observed between human and mouse adipose tissue, many genes were differentially regulated in the two species, including genes involved in insulin signaling (PRKAG2, PFKFB3), PPAR signaling (PPARG, ACSL1, HMGCS2, SLC22A5, ACOT1), glycogen metabolism (PCK1, PYGB), and lipid droplets (PLIN1, PNPLA2, CIDEA, CIDEC). In conclusion, although numerous genes and pathways are regulated similarly by fasting in human and mouse adipose tissue, many genes show very distinct responses to fasting in humans and mice. Our data provide a useful resource to study adipose tissue function during fasting.
Project description:Prolonged fasting-induced changes in rat white adipose tissue (epidydimal) transcriptome White adipose tissue is a central place to energy storage and a major endocrine organ. However, adipose molecular mechanisms have been poorly studied during prolonged fasting. To fill this gap, the aim of this study was to decipher transcriptomic regulations in rat adipose tissue during phase 2 (lipid mobilization) and phase 3 (protein catabolism) of prolonged fasting compared to the fed state. We describe a regulatory transcriptional program in epididymal adipose tissue in line with lipogenesis repression during both phases, and that would favor lipolysis during phase 2 and repress it during phase 3. Such regulations notably involve selective (i.e. phase-dependent) changes in gene expression levels of lipases, lipid droplet-associated factors, and the proteins involved in cAMP-dependent and cAMP-independent regulation of lipolysis. The mRNA levels of adipose-secreted factors were globally consistent with the repression of insulin signalling during prolonged fasting. Regulations of leptin and adiponectin levels could be related to their respective role in triggering refeeding during late fasting and controlling lipid metabolism. Specific responses reflecting adipose tissue inflammation, increased fibrinolysis and a possible protein catabolism-related energy saving mechanism were also recorded during phase 3. These data thus provide a comprehensive molecular basis of adipose tissue responses according to the fasting stage.