TRIMERIC G PROTEINS AND CONTROL OF HOMEOSTASIS

描述：（改编自申请人的摘要）：我们的长期目标是研究异源三聚体G蛋白的跨膜信号传导。跨膜信号G蛋白的结构和大多数分子方面已经得到解决，但它们各自参与复杂的稳态过程，如炎症反应，疼痛感知，行为和正常神经元的维持仍然是未知的。在前一个和最后一个授予期间，我们开始通过创建缺乏特定G蛋白的小鼠（敲除小鼠）来解决G蛋白在体内平衡中的作用。我们现在已经单独敲除了15个G蛋白α亚基基因中的4个：Gi 1，Gi 2，Gi 3和Go，我们还进行了双重和Gi 1/Gi 3敲除。这些G蛋白形成非感觉性百日咳毒素（PTX）敏感性G蛋白组，其将一组不同的受体与一组共同的效应物偶联。其中两个基因敲除（Gi 1和Gi 3，以及它们的组合）到目前为止没有症状。Gi 2-/-小鼠发生溃疡性结肠炎（UC）和腺癌，但以环境敏感的方式，即，这取决于菌株（基因组背景）。Go-/-小鼠具有多种神经学改变，并将这种表型称为“神经元”。Go-/-小鼠还显示出Ca 2+通道功能的意外改变，并且当经受葡萄糖负荷时，响应于比对照更严格的对Ca 2+的控制。在未来几年，我们建议：A。为了完成Gz G蛋白的破坏，其与失活的G蛋白α亚基共享高度的结构和功能相似性，将同一组受体偶联至同一组效应物，但对PTX不敏感。这将通过繁殖产生复合G蛋白缺陷来补充。B.寻找和表征一个或多个负责抑制（或促进）Gi 2-/-小鼠中UC和腺癌发展的基因。C.寻找中枢神经系统中受Go缺乏影响的神经递质系统，如果可能，根据中枢神经系统运动回路的现有理论解释旋转体表型。和d.在体内和体外表征Go-/-胰岛的胰岛素分泌特性。UC和/或腺癌形成的一个或多个修饰基因的鉴定可能有助于阐明人类UC及其并发症（腺癌）的病因。研究Gz的作用有望为血栓形成的分子机制提供新的线索。由于缺乏Go而改变的机制的阐明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.