MODULATION OF INSULIN RECEPTOR FUNCTION

工作总结：胰岛素诱导多效性和 高度整合的一系列代谢和有丝分裂反应通过其 细胞内信号系统。在胰岛素结合时，固有的 胰岛素受体的酪氨酸激酶活性被激活，从而 导致受体及其底物的磷酸化 酪氨酸残留物。这些细胞内底物的磷酸化 导致它们与含有SH2结构域的分子结合 产生下行信号。这一缺陷导致了 组织对胰岛素反应的特征性减弱(也称为 肥胖相关2型糖尿病患者的胰岛素抵抗)被认为是 在胰岛素受体的下游。然而，有证据表明 它支持维护 胰岛素受体的稳态磷酸化可能代表着 攻击病理性胰岛素的有效治疗途径 抵抗。使用从独特序列中提取的合成肽 在胰岛素受体胞浆区域，我们发现了一种 能够选择性增强的多肽(称为多肽HC) 胰岛素受体在体外和完整细胞中都有功能，而 对胰岛素样生长因子-1受体无影响 功能。我们还报道了这种多肽与胰岛素的结合。 细胞中的受体β亚基，从而提供了为数不多的证据之一 用于受体结构域之间的协同作用。我们的 实验室最近开发了一种微型发电机方法，可以 稳定表达受体片段，该受体片段可以特异性地 调节细胞中的胰岛素受体功能。另外，一名突变体 缺乏这种受体片段的胰岛素受体已经 构建并在中国仓鼠卵巢细胞中稳定表达。 我们计划研究这种突变对胰岛素的影响。 受体介导的信号，并确定是否引入 通过微基因方法丢失的片段将恢复胰岛素 对控制级别的响应能力。

Summary of work: Insulin elicits pleiotropic and highly integrated series of metabolic and mitogenic responses via its intracellular signaling systems. Upon insulin binding, the intrinsic tyrosine kinase activity of the insulin receptor is activated, thereby leading to phosphorylation of the receptor and its substrates on tyrosine residues. Phosphorylation of these intracellular substrates leads to their association with SH2 domain-containing molecules to generate downstream signals. The defect that causes the characteristic diminution of tissue responses to insulin (also termed insulin resistance) in obesity-related type 2 diabetics is thought to be downstream of the insulin receptor. However, evidence has been presented which supports the notion that maintaining the steady-state phosphorylation of the insulin receptor may represent a valid therapeutic approach for attacking pathologic insulin resistance. Using synthetic peptides derived from unique sequences in the insulin receptor cytoplasmic domain, we have identified a peptide (termed peptide HC) capable of enhancing selectively insulin receptor function both in vitro and in intact cells, while having no effect on insulin-like growth factor 1 (IGF-1) receptor function. We also reported the binding of this peptide to the insulin receptor beta-subunit in cells, thus providing one of few evidences for synergistic interaction between receptor domains. Our laboratory has recently developed a minigene approach that allows stable expression of a receptor fragment that can specifically modulate insulin receptor functions in cells. In addition, a mutant insulin receptor that lacks this receptor fragment has been constructed and expressed stably in Chinese hamster ovary cells. We plan to examine the effect such mutation will have on insulin receptor-mediated signals, and determine whether introduction of the missing fragment by the minigene approach will restore insulin responsiveness to control levels.