CELLULAR MECHANISM FOR INSULIN RESISTANCE

这项研究提案的最终目的是确定 胰岛素中胰岛素受体底物(IRS-1)的反馈抑制 抵抗。分化的3T3-L1脂肪细胞，用 磷酸酶抑制剂冈田酸(OKA)已被证明 胰岛素抵抗，伴有胰岛素刺激的酪氨酸减少 IRS-1的磷酸化和丝氨酸/苏氨酸激酶活性的增加 能够使IRS-1磷酸化。我们正试图确定 丝氨酸苏氨酸激酶活性，首先通过检测两种作用 可能的候选蛋白，MAP激酶和蛋白激酶C，并通过 试图提纯一种新的激酶。我们将尝试建立 通过检测这一激酶活性的影响来研究其生物学相关性 表达IRS-1突变体，缺少一个或多个潜在的Serv/Thr OKA上的磷酸化位点，诱导胰岛素抵抗。我们希望 建立丝氨酸/苏氨酸转运蛋白磷酸化之间的直接相关性 胰岛素受体IRS-1及其酪氨酸磷酸化水平的降低 刺激IR，降低PI-3蛋白结合，降低血糖 领悟。

The ultimate purpose of this research proposal is to determine the role of feedback inhibition of Insulin Receptor Substrate (IRS-1) in insulin resistance. Differentiated 3T3-L1 adipocytes, treated with the phosphatase inhibitor okadate acid (OKA), have been shown to exhibit insulin resistance, accompanied by decreased insulin stimulated tyrosine phosphorylation of IRS-1 and an increase serine/threonine kinase activity capable of phosphorylating IRS-1. We are attempting to identify the serine threonine kinase activity, first by examining the role of two likely candidate proteins, MAP kinase and Protein Kinase C, and by attempting to purify a novel kinase. We will attempt to establish the biological relevance of this kinase activity by examining the effect of expressing IRS-1 mutants, lacking one or more of the potential ser/thr phosphorylation sites, on the OKA induced insulin resistance. We hope to establish a direct correlation between ser/thr phosphorylation of IRS-1 and a decrease in its tyrosine phosphorylation by insulin stimulated IR, decreased PI-3 kinase binding and decreased glucose uptake.