Depletion of TBC1D4 improves the metabolic exercise response by overcoming genetically induced peripheral insulin resistance

Abstract

<p dir="ltr">The RabGTPase-activating protein (RabGAP) TBC1D4 (=AS160) represents a key component in the regulation of glucose transport into skeletal muscle and white adipose tissue (WAT) and is therefore crucial during the development of insulin resistance and type-2 diabetes. Increased daily activity has been shown to be associated with improved postprandial hyperglycemia in allele carriers of a loss-of-function variant in the human <i>TBC1D4</i> gene. Using conventional <i>Tbc1d4</i>-deficient mice (D4KO) fed a high-fat diet (HFD), we show that already a moderate endurance exercise training leads to substantially improved glucose and insulin tolerance and enhanced expression levels of markers for mitochondrial activity and browning in WAT from D4KO animals. Importantly, <i>in vivo</i> and <i>ex vivo</i> analyses of glucose uptake revealed increased glucose clearance in interscapular brown adipose tissue (iBAT) and WAT from trained D4KO mice. Thus, chronic exercise is able to overcome the genetically induced insulin resistance caused by the <i>Tbc1d4</i>-depletion. Gene variants in <i>TBC1D4</i> may be relevant in future precision medicine as determinants of exercise response.</p>