TRIMERIC G PROTEINS AND CONTROL OF HOMEOSTASIS

描述：(摘自申请者的摘要)：我们的长期目标是研究异源三聚体G蛋白的跨膜信号。跨膜信号G蛋白的结构和大部分分子方面已经得到解决，但它们各自参与复杂的动态平衡过程，如炎症反应、痛觉、行为和维持正常血糖仍很不清楚。在前一次和最后一次授予期间，我们通过创造缺乏特定G蛋白的小鼠(基因敲除小鼠)，开始研究G蛋白在动态平衡中的作用。我们现在已经分别敲除了15个G蛋白α亚单位基因中的4个：Gi1、GI2、Gi3和Go，还有一个Double和Gi1/Gi3基因敲除。这些G蛋白形成了一组非感觉性百日咳毒素(PTX)敏感的G蛋白，它将一组不同的受体与一组共同的效应器偶联。其中两个淘汰赛(Gi1和Gi3及其组合)到目前为止还没有症状。GI2-/-小鼠发生溃疡性结肠炎(UC)和腺癌，但以一种上下文敏感的方式，即取决于菌株(基因组背景)。GO-/-小鼠有多种神经系统改变，并将这种表型称为“旋转体”。GO-/-小鼠还表现出钙离子通道功能的意外变化，当受到葡萄糖负荷时，与对照组相比，小鼠对血糖的控制要严格得多。在接下来的几年里，我们建议：a.为了完成对Gz G蛋白的破坏，Gz G蛋白与失活的G蛋白α亚基具有高度的结构和功能相似性，将同一组受体偶联到同一组效应器上，但对PTX不敏感。作为补充，将通过培育复合G蛋白缺陷症来创造。寻找和鉴定一个或多个抑制(或促进)GI2-/-小鼠UC和腺癌发展的基因。C.寻找围棋缺乏对中枢神经系统影响的神经递质系统(S)，并在可能的情况下，根据现有的中枢神经系统运动回路理论解释旋转表型。以及D.表征体内和体外GO-/-胰岛的胰岛素分泌特性。鉴定UC和/或腺癌形成的一个或多个修饰基因可能有助于阐明人类UC及其并发症(腺癌)的病因学。对Gz作用的研究有望为血栓形成的分子机制提供新的线索。阐明GO缺乏改变的机制(S)可能有助于理解人类运动障碍，并可能为II型糖尿病的发展和/或治疗提供新的线索。

DESCRIPTION: (Adapted from applicant's abstract): Our long term goals are to study transmembrane signalling by heterotrimeric G proteins. The structure and most molecular aspects of transmembrane signalling G proteins have been solved, but their respective participation in complex homeostatic processes such as inflammatory reactions, pain perception, behavior and maintenance of normal glycemia remains largely unknown. During the previous and this last granting period we began addressing the roles of G proteins in homeostasis by creating mice lacking specific G proteins (knockout mice). We have now individually knocked out four of the 15 G protein alpha subunit genes: Gi1, Gi2, Gi3 and Go, and we also have a double and Gi1/Gi3 knockout. These G proteins form the group of non-sensory pertussis toxin (PTX)-sensitive G proteins which couples a distinct set of receptors to a common set of effectors. Two of the knockouts (Gi1 and Gi3, and their combination) are so far asymptomatic. Gi2-/- mice develop ulcerative colitis (UC) and adeno-carcinomas, but in a context sensitive manner, i.e., depending on the strain (genomic background). Go-/-mice have multiple neurological alterations and term this phenotype 'rotator'. Go-/- mice also show unexpected alterations in Ca2+ channel function and, when subjected to a glucose load, respond with a much tighter control of glycemia than controls. For the coming years we propose: a. To complete the disruption of the Gz G protein, which shares with the inactivated G protein alpha subunits a high degree of structural and functional similarity, coupling the same set of receptors to the same set of effectors, but is PTX- insensitive. This will be complemented by the creation by breeding of the compound G protein deficiencies. b. To search for and characterize one or more genes responsible for suppression (or promotion) of the development of UC and adenocarcinomas in Gi2-/- mice. c. To search for the neurotransmitter system(s) in the CNS affected by lack of Go and, if possible, interpret the rotator phenotype in terms of existing theories of central nervous system motor circuits. And d. to characterize insulin secreting properties of Go-/- islets in vivo and in vitro. The identification of one or more modifier genes of UC and/or adenocarcinoma formation may aid in the elucidation of the etiology of human UC and its complications (adenocarcinomas). Investigation of the role of Gz is expected to shed new light on molecular mechanisms involved in thrombus formation. The elucidation of the mechanism(s) altered by lack of Go may aid in the understanding of human motor disorders and may shed new light on development and/or treatment of type II diabetes.