Disruption of Hypoxia-Inducible Factor 1 in Adipocytes Improves Insulin Sensitivity and Decreases Adiposity in High-Fat Diet-Fed Mice

OBJECTIVE-Obesity, insulin resistance, and type 2 diabetes form a tightly correlated cluster of metabolic disorders in which adipose is one of the first affected tissues. The role of hypoxia and hypoxia-inducible factor 1 (HIF1) in the development of high-fat diet (HFD)-induced obesity and insulin resistance was investigated using animal models. RESEARCH DESIGN AND METHODS-Mice with adipocyte-specific targeted disruption of the genes encoding the HIFI obligatory subunits Hif1 alpha or Arnt (Hif1 beta) were generated using an aP2-Cre transgene with the Cre/LoxP system. The mice were fed an HFD for 12 weeks and their metabolic phenotypes were determined. Gene expression patterns in adipose tissues were also determined by microarray and quantitative PCR. RESULTS-On an HFD, adipocyte-specific ARNT knockout mice and adipocyte-specific HIF1 alpha knockout mice exhibit similar metabolic phenotypes, including reduced fat formation, protection from HFD-induced obesity, and insulin resistance compared with similarly fed wild-type controls. The cumulative food intake remained similar; however, the metabolic efficiency was lower in adipocyte-specific HIF1 alpha knockout mice. Moreover, indirect calorimetry revealed respiratory exchange ratios were reduced in adipocyte-specific HIF1 alpha knockout mice. Hyperinsulinemic-euglycemic clamp studies demonstrated that targeted disruption of HIF1 alpha in adipocytes enhanced whole-body insulin sensitivity. The improvement of insulin resistance is associated with decreased expression of Socs3 and induction of adiponectin. CONCLUSIONS-Inhibition of HIF1 in adipose tissue ameliorates obesity and insulin resistance. This study reveals that HIF1 could provide a novel potential therapeutic target for obesity and type 2 diabetes. Diabetes 60:2484-2495, 2011