INSULIN RECEPTOR THIOL REACTIVITY AND INSULIN SIGNALING

胰岛素受体硫醇反应性和胰岛素信号传导

• 批准号: 6288766
• 负责人: MICHEL BERNIER
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6288766
• 关键词: CHO cells; biocytin; biotin; hydrogen peroxide; immunoprecipitation; insulin receptor; oxidative stress; oxidoreductase inhibitor; protein structure function; sulfhydryl reagents; thiols; vanadium

Summary of work: The insulin receptor is a homodimer consisting of two alpha- and two beta-subunits linked together by disulfide bonds. Insulin binding to the alpha-subunit triggers the intrinsic tyrosine kinase function of the cytoplasmic domain of the receptor beta-subunit. Activation of this receptor by insulin plays an important role in mediating diverse physiological processes, including modulation of glucose homeostasis and gene expression. Earlier findings have found that the functional activity of the insulin receptor can be modulated by redox regulation in the cellular environment. For example, addition of antioxidant such as N-acetyl-L-cysteine (NAC) to cells has been associated with a reduction in insulin receptor catalytic function, whereas cell treatment with hydrogen peroxide promotes insulinomimetic effects. We postulated that reduced glutathione (GSH), which constitutes the major source of plasma nonprotein thiols, and NAC may play a role in altering thiol reactivity of the insulin receptor and thus reduce insulin responsiveness. In a recent published study, we provided the first evidence that the insulin receptor alpha-subunit contains a select group of disulfides whose redox status can be rapidly and reversibly altered by the reducing agents GSH and NAC. While having little impact on insulin binding, GSH markedly attenuated insulin signal transduction. The oligomeric structure of the insulin receptor was not affected by neither of these compounds. We plan to identify the reactive receptor thiol group(s). Such knowledge will allow mutagenic structure/function analysis of this select group of insulin receptor disulfides.

工作总结：胰岛素受体是一种同源二聚体，由两个α-亚基和两个β-亚基通过二硫键连接在一起。胰岛素与α-亚基结合，触发受体β-亚基胞质区域的固有酪氨酸激酶功能。胰岛素激活该受体在调节葡萄糖稳态和基因表达等多种生理过程中起着重要作用。早期的发现发现，胰岛素受体的功能活性可以通过细胞环境中的氧化还原调节来调节。例如，在细胞中加入抗氧化剂如N-乙酰-L-半胱氨酸(NAC)会降低胰岛素受体的催化功能，而用过氧化氢处理细胞则会促进胰岛素样作用。我们推测，还原型谷胱甘肽(GSH)是血浆非蛋白硫醇的主要来源，NAC可能在改变胰岛素受体的硫醇反应性从而降低胰岛素反应性方面发挥作用。在最近发表的一项研究中，我们提供了第一个证据，证明胰岛素受体α亚单位包含一组精选的二硫化物，其氧化还原状态可以被还原剂GSH和NAC迅速和可逆地改变。GSH在对胰岛素结合影响不大的同时，显著减弱胰岛素信号转导。胰岛素受体的寡聚体结构不受这两种化合物的影响。我们计划鉴定反应性受体硫醇基团(S)。这些知识将使这组精选的胰岛素受体二硫化物的突变结构/功能分析成为可能。