Selective Targeting of G Protein beta gamma Subunits with Small Molecules

摘要 G蛋白偶联受体（GPCR）介导多种激素和神经递质的作用 来控制所有哺乳动物细胞的功能因此，GPCR是治疗剂的主要靶标。个人 GPCR直接偶联到异源三聚体G蛋白A和B亚基的不同互补物， 下游信号传导途径，以形成决定GPCR功效的细胞反应。G和 G亚基直接与效应器相互作用以产生细胞反应。我们的实验室主要关注 并鉴定了一系列与G β亚基结合的小分子，以“偏置”信号传导 GPCR下游的通路。这些抑制剂已被广泛应用于解剖G蛋白的功能， 生物学，并验证作为一个可行的治疗靶点的G蛋白。最近我们发现了一种小分子 激活G蛋白A亚基信号而不激活G蛋白A亚基。我们应用这个工具来研究 在免疫细胞中的信号传导，以揭示G蛋白在趋化因子中令人兴奋的和以前未被认识的作用， 化学引诱物受体信号传导在这个建议中，我们将详细研究G蛋白激活分子 在分子水平上发挥作用，并探讨G蛋白在趋化因子受体信号传导中的机制作用。 以下具体目标。目标1。确定12155和M119/gallein对G 蛋白质亚基相互作用和GPCR偶联。目标二。确定G β iGTP的机制- 细胞迁移和粘附的依赖性调节。目标3：G_（50）的时空调控分析 在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一个 新的分子靶点和细胞功能的G蛋白在调节整合素的功能，将有广泛的 化学引诱物/趋化因子受体和整合素调节的意义。

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.