Effect of Acute Physiologic Hyperinsulinemia on Gene Expression in Human Skeletal Muscle in vivo

This study was undertaken to test the hypothesis that short term exposure (4 hours) to physiologic hyperinsulinemia in normal, healthy subjects without a family history of diabetes would induce a low grade inflammatory response, independently of glycemic status. We performed euglycemic hyperinsulinemic (80 mU/m2/min) clamps in 12 healthy, insulin sensitive subjects with no family history of diabetes followed by biopsies of the vastus lateralis muscle taken basally and after 30 and 240 minutes of insulin infusion. Gene expression profiles were generated using Affymetrix HG-U133A arrays. No probe sets had significantly altered expression at 30 minutes of the insulin clamp, but 121 probe sets (117 upregulated and 4 downregulated) were significantly altered after 240 minutes. Hyperinsulinemia in normal, healthy human subjects increased the mRNAs for a number of inflammatory genes and transcription factors. Microarray and quantitative RT-PCR revealed the upregulation of chemokine, cc motif, ligand 2 (CCL2), CCL8, thrombomodulin (THBD), ras-related associated with diabetes (RRAD), metallothionein (MT), and serum/glucocorticoid regulated kinase (SGK), and downregulation of CITED2 (a CREB-binding protein-interacting transactivator), a known coactivator of PPAR-alpha. Interestingly, SGK and CITED2 are located at chromosome 6q23, where we previously detected strong linkage to hyperinsulinemia. A control saline infusion performed on 3 normal, healthy subjects without a family history of diabetes demonstrated that the genes altered following the euglycemic-hyperinsulinemic clamp were due to insulin and independent of biopsy removal. This study demonstrates that insulin acutely regulates the expression of genes involved in inflammation and transcription, and identifies several candidate genes/pathways for further investigation.

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Coletta DK, Balas B, Chavez AO, Baig M, Abdul-Ghani M, Kashyap SR, Folli F, Tripathy D, Mandarino LJ, Cornell JE, Defronzo RA, Jenkinson CP