Selective Targeting of G Protein beta gamma Subunits with Small Molecules

摘要 G蛋白偶联受体(GPCRs)介导多种激素和神经递质的作用 控制所有哺乳动物细胞的功能。因此，GPCR是治疗学的主要靶点。个体 GPCR直接与异源三聚体G蛋白和亚基的不同互补作用 下游信号通路塑造细胞反应，从而决定gpr的疗效。G和 G亚基直接与效应器相互作用，产生细胞反应。我们的实验室主要集中在 关于G亚单位信号转导的研究，并发现了一系列与G结合的小分子来“偏向”信号转导 GPCRs下游的道路。这些抑制剂已被广泛应用于剖析G-功能 生物学，并验证G作为一个可行的治疗靶点。最近，我们发现了一种小分子 这激活了G蛋白亚单位信号而不激活G蛋白亚单位。我们已经将这一工具应用于研究 在免疫细胞中发出信号以揭示GI在趋化因子中令人兴奋和以前未被认识的作用- 趋化受体信号。在这项提案中，我们将详细研究G如何激活分子 在分子水平上发挥作用，并探讨GI在趋化受体信号转导中的机制作用 以下是具体目标。目的1.确定12155和M119/Gallein对G的作用机制 蛋白质亚单位相互作用和GPCR偶联。目的2.确定G--IGTP的作用机制(S) 依赖于细胞迁移和黏附的调节。目的3.G-I的时空调控分析 趋化因子依赖的定向细胞迁移中的激活。我们相信，这些研究将揭示出 GI在调节整合素功能中的新分子靶点和细胞功能将具有广泛的 趋化因子/趋化因子受体和整合素调控的意义。

Abstract G protein-coupled receptors (GPCRs) mediate the actions of a wide variety of hormones and neurotransmitters to control functions in all mammalian cells. As such, GPCRs are major targets of therapeutics. Individual GPCRs directly couple to distinct complements of heterotrimeric G protein  and  subunits that drive downstream signaling pathways to shape the cellular responses that determine GPCR efficacy. Both G and G subunits interact directly with effectors to produce cellular responses. Our laboratory has focused largely on G subunit signaling and has identified a series of small molecules that bind to G to “bias” signaling pathways downstream of GPCRs. These inhibitors have been applied extensively to dissect G functions in biology, and to validate G as a viable therapeutic target. Most recently we have identified a small molecule that activates G subunit signaling without activating G protein  subunits. We have applied this tool to study signaling in immune cells to reveal exciting and previously unappreciated roles for Gi in chemokine- chemoattractant receptor signaling. In this proposal we will examine in detail how G activating molecules function at a molecular level, and explore the mechanistic role for Gi in chemoattractant receptor signaling in the following specific aims. Aim 1. Determination of the mechanisms of action of 12155 and M119/gallein on G protein subunit interactions and GPCR coupling. Aim 2. Determining the mechanism(s) for GiGTP- dependent regulation of cell migration and adhesion. Aim 3. Analysis of spatiotemporal regulation of Gi activation in chemoattractant-dependent directional cell migration. We believe that these studies will reveal a new molecular target and cellular function for Gi in regulation of integrin function that will have wide implications for chemoattractant/chemokine receptor and integrin regulation.