Project description:At 2 months of age, liver-specific insulin receptor knockout (LIRKO) mice present hyperglycemia and hyperinsulinemia. Furthermore, LIRKO mice have increased levels of hepatic cholesterol. Indeed, many changes seen in cholesterol metabolism in LIRKO mice are also observed in humans with metabolic syndrome. For example, both show decreased levels of HDL and increased secretion of apoB and VLDL. These findings make the LIRKO mouse a unique non-dietary model of insulin resistant, hyperglycemia, dyslipidemia and atherosclerosis that resembles several clinical features of the human metabolic syndrome. By hepatic transcriptomic analysis of the wild-type (WT) offspring of LIRKO mice, we identify that members of the TGF-β family are differentially expressed in the offspring, including the NREP and GDF15.
Project description:Liver-specific insulin receptor knockout (LIRKO) mouse is a unique non-dietary model of insulin resistant, hyperglycemia, dyslipidemia and atherosclerosis that resembles several clinical features of the human metabolic syndrome. By enhanced reduced representation bisulfite sequencing (ERRBS) analysis of the livers of wild-type (WT) offspring of LIRKO mice, we identified that genes with differential DNA methylation were enriched for cholesterol synthesis, MAPK, AKT, insulin and TGF-β signaling, including the NREP and GDF15.
Project description:Gene expression was analyzed by gene array in liver RNA collected from 11-12 week old male IR floxed, LIRKO, IR/FoxO1 floxed and LIRFKO mice either a) following an overnight 24 hr fast, b) 60 min after dextrose (2 g/kg ip) was administered to overnight fasted mice, or c) 6 hr after fasted mice were allowed to refeed on standard chow.
Project description:The effect of liver specific deletion of the insulin receptor substrate-1 (Irs1) and/or Irs2 upon gene expression in the fasted and fed liver of mice; and the effect of liver specific Foxo1 deletion in the Irs1 and Irs2 knockout liver during fasting and feeding.
Project description:Decreased skeletal muscle strength and mitochondrial dysfunction are characteristic of diabetes. Action of insulin through insulin receptor (IR) and IGF-1 receptor (IGF1R) maintain muscle mass via suppression of FoxOs, but whether FoxO activation coordinates atrophy in concert with mitochondrial dysfunction is unknown. In the absence of systemic glucose or lipid abnormalities, muscle-specific IR knockout (MIRKO) or combined IR/IGF1R knockout (MIGIRKO) impaired mitochondrial respiration, decreased ATP production, and increased ROS. These mitochondrial abnormalities were not present in muscle-specific IR/IGF1R and FoxO1/3/4 quintuple knockout mice (QKO). Although autophagy was increased when IR/IGF1R were deleted in muscle, mitophagy was not increased. Mechanistically, RNA-seq revealed that complex-I core subunits were decreased in MIGIRKO muscle, and these were reversed with FoxO knockout. Thus, insulin-deficient diabetes or loss of insulin/IGF-1 action in muscle decreases complex-I driven mitochondrial respiration and supercomplex assembly, in part by FoxO-mediated repression of Complex-I subunit expression.
Project description:Control and Liver Insulin Receptor KO mice (LIRKO) were sacrificed in the non-fasted state. RNA was prepared from liver samples and subjected to expression microarray analysis Each array was hybridized with sample derived from 2-3 mice of the same genotype. Three arrays per group were used.
Project description:Control and Liver Insulin Receptor KO mice (LIRKO) were sacrificed in the non-fasted state. RNA was prepared from liver samples and subjected to expression microarray analysis Each array was hybridized with sample derived from 2-3 mice of the same genotype.
