Xiao Jian Sun, Ph.D.

Molecular Mechanism of Insulin Signaling and Insulin Resistance

Research Summary

Major interests of Dr. Sun’s laboratory are the molecular mechanism of insulin action and the molecular basis of insulin resistance. IRS-1 and IRS-2 (IRS-proteins) are indispensable in normal insulin actions in animals. Serine phosphorylation and ubiquitin-proteasome degradation of IRS-proteins have been shown to attenuate insulin action and hypothesized to be two potential mechanisms for insulin resistance. The investigations in Dr. Sun’s laboratory are currently focused on the efforts to identify specific serine kinases that phosphorylate IRS-proteins, and ubiquitin enzymes and regulatory components that are required for the proteasome degradation of IRS-proteins.

Selected Papers

Lehmann R, Beck A, Möschel K, Schmidt EK, Deeg M, Rapp E, Sun XJ, Kellerer M, Voelter W, Schleicher ED, Häring HU. (2002). Protein kinase C-* phosphorylates serine/threonine residues at the C-terminal binding motif of the tyrosine phosphatase SHP-2 of insulin receptor substrate 1. Signal Transduction. 1-2, 40-45.

Horike N, Takemori H, Katoh Y, Doi J, Min L, Asano T, Sun XJ, Yamamoto H, Kasayama S, Muraoka M, Nonaka Y, Okamoto M. (2003). Adipose-specific Expression, Phosphorylation of Ser794 in Insulin Receptor Substrate-1, and Activation in Diabetic Animals of Salt-inducible Kinase-2. J. Biol. Chem. 278(20):18440-18447

Li Y, Eitan S, Wu J, Wu J, Evans CJ, Kieffer B, Sun XJ, Polakiewicz RD. (2003). Morphine-induces desensitization of insulin receptor signaling. Molec. Cell Biol. 23(17), 6255-6266.