1517-P: Rev-Erba as an Intermediate between Regulation of Circadian Rhythm and Skeletal Muscle Insulin Sensitivity

Rev-Erbα is a nuclear receptor involved in the control of circadian rhythm and regulates the transcription of many metabolic genes. Skeletal muscle is responsible for >75% of postprandial glucose uptake, and this is significantly reduced in insulin-resistant and type 2 diabetic (T2D) individuals. To determine the potential role of Rev-Erbα in muscle in T2D, we have used human induced pluripotent stem cells (iPSCs) from control and T2D patients differentiated into myoblasts (iMyos) to study its role in insulin action and metabolism in the absence of confounding circulating factors. We find that iMyos from T2D donors have a 25% decrease (p=0.005) in the Rev-Erbα mRNA expression, and this is paralleled by a 35% decrease (p=0.03) in Rev-Erbα protein. This is also accompanied by significant 22-45% reductions in insulin-stimulated phosphorylation of pIRβ^Y1146, pIRS1^Y895, pAkt^S473, pGSK3β^S9, and an ~30% decrease in insulin-stimulated glucose uptake. Treatment of T2D iMyos with a Rev-Erbα agonist rescues the impaired glucose uptake in the T2D cells to control levels. CRISPR/Cas9 knockout of Rev-Erbα in murine C2C12 muscle cells results in reduced insulin-stimulated insulin signaling and glucose uptake, paralleling the defects observed in the human T2D iMyos. RNAseq analysis of these knockout cells revealed changes in expression of genes associated with insulin action, including downregulation of Irs2, Gab1, and Shc2. Combining these data with Rev-Erbα ChipSeq data identified 150 genes in the Rev-Erbα^-/- cells that are directly targeted and repressed by Rev-Erbα via its binding in the promoter region. These genes are enriched in pathways related to mitochondria physiology and insulin resistance. Taken together, these data demonstrate that Rev-Erbα provides cross-talk between circadian regulation and metabolism by acting as a positive regulator of insulin sensitivity, glucose uptake and mitochondrial function, and this process is attenuated in skeletal muscle in human T2D.