ANTIAPOPTOTIC FUNCTION OF THE INSULIN RECEPTOR

胰岛素受体的抗凋亡功能

• 批准号: 6288768
• 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/6288768
• 关键词: CHO cells; apoptosis; biological signal transduction; glucose metabolism; guanine nucleotide binding protein; insulin receptor; phosphorylation; protein kinase; receptor expression; site directed mutagenesis; transfection

Summary of work: Apoptosis, or programmed cell death, is a natural phenomenon that plays a major role in normal turnover of cells and pathological processes, including autoimmune diabetes and diabetic neuropathy. Numerous evidences indicate that activation of the insulin receptor confers cell survival, in part, by activating transcription factors that are known to be involved in the control of the apoptotic process. In a recent published study, we reported that farnesylation of Ras-related small GTP-binding proteins may be involved in the antiapoptotic protection conferred by the insulin receptor. There are only three members of the Ras family that are known to be farnesylated and targeted at the plasma membrane. Transfection of cells with wild- type and dominant-negative mutant of these small GTP-binding proteins is underway. Meanwhile, we established that expression of a transdominant inhibitory mSOS1 mutant blocked insulin-mediated activation of p21Ras but not the antiapoptotic effects of insulin, as assessed by levels of peroxynitrite, activity of caspase-3, DNA fragmentation, cytochrome c release from mitochondria, and fluorescence-activated cell sorting. The pretreatment with pertussis toxin (PTX) markedly attenuated protection offered by insulin. We concluded that insulin inhibits apoptosis via a Ras-independent, but PTX-sensitive, pathway. There are several signaling molecules that are implicated in the control of cell death. Interestingly, the interaction between the insulin receptor and PTX-sensitive inhibitory G-proteins represents a regulated integrative point for cross-talk between tyrosine kinase receptor- and cyclic AMP-dependent signaling cascades. Consequently, we plan to use antisense strategies to investigate the role of selective inhibitory G-proteins (e.g., i1, i2 or i3) in the antiapoptotic function of insulin. Lastly, the devastating complications of diabetes are the results of prolonged periods of hyperglycemia. Byproducts of cellular respiration as well as high glucose concentrations found in diabetic conditions can result in cell death. We plan also to characterize the mechanisms by which glucose and its metabolites function as apoptotic inducers. - Insulin receptors; Signal transduction; Apoptosis; CHO cells; Farnesylation

工作总结：细胞凋亡或程序性细胞死亡是一种自然现象，在细胞的正常更新和病理过程中起主要作用，包括自身免疫性糖尿病和糖尿病神经病变。大量证据表明，胰岛素受体的激活部分地通过激活已知参与细胞凋亡过程控制的转录因子来赋予细胞存活。在最近发表的一项研究中，我们报道了Ras相关的小GTP结合蛋白的法尼基化可能参与胰岛素受体赋予的抗凋亡保护。已知Ras家族中只有三个成员被法尼基化并靶向质膜。用这些小GTP结合蛋白的野生型和显性阴性突变体转染细胞正在进行中。与此同时，我们建立了一个反式显性抑制mSOS 1突变体的表达阻断胰岛素介导的激活p21 Ras，但不胰岛素的抗凋亡作用，评估过氧亚硝酸盐的水平，caspase-3的活性，DNA片段化，细胞色素c从线粒体的释放，和荧光激活的细胞分选。百日咳毒素（PTX）预处理明显减弱胰岛素的保护作用。我们的结论是，胰岛素抑制细胞凋亡通过Ras的独立，但PTX敏感，途径。有几种信号分子参与细胞死亡的控制。有趣的是，胰岛素受体和PTX敏感的抑制性G蛋白之间的相互作用代表了酪氨酸激酶受体和环AMP依赖性信号级联之间的串扰的调节整合点。因此，我们计划使用反义策略来研究选择性抑制性G蛋白（例如，i1、i2或i3）在胰岛素的抗凋亡功能中的作用。最后，糖尿病的毁灭性并发症是长时间高血糖的结果。细胞呼吸的副产物以及在糖尿病条件下发现的高葡萄糖浓度可导致细胞死亡。我们还计划表征葡萄糖及其代谢产物作为凋亡诱导剂的机制。- 胰岛素受体;信号转导;细胞凋亡; CHO细胞;法尼基化