Mechanism and role of G-protein subunit translocation in cell signaling

描述(申请人提供)：比任何其他蛋白质家族更多针对G蛋白偶联受体(GPCRs)的治疗性药物。G蛋白通过与质膜上的GPCRs相互作用，传递起始于细胞表面的信号。这项研究的长期目标是确定新的G蛋白相互作用，可以作为新的治疗药物的靶点。G蛋白异源三聚体由α、β和伽马亚基组成。当G蛋白在PM激活时，阿尔法亚单位和β-伽马二聚体都激活下游的信号级联。传统上，两人都被认为在这一过程中仍将留任首相。最近，人们发现β-伽马二聚体可以离开质膜，转移到高尔基体和内质网(ER)，靶向性和速率取决于特定的伽马亚单位类型。这些发现需要更好地理解活细胞中G蛋白亚基快速和可逆移动背后的机制，以及它在指定细胞对GPCR刺激的反应中的功能。β-伽马易位的依赖于伽马的动力学为识别控制易位的特定G蛋白-受体相互作用及其生理作用提供了独特的工具。我们将利用这些差异动力学来实现两个特定的目标。目的1：验证γ亚基与受体之间的相互作用是受体刺激的G-β-γ易位的主要调节因子的假设。目的2：验证G-β-γ转位到内质网(ER)靶向三磷酸肌醇受体并调节钙释放的假设。这些实验将验证基于证据的假设，即伽马亚基通过调节GPCR激活后β-伽马二聚体在细胞内的运动来促进G蛋白信号的特异性。这些实验的发现有可能识别伽马亚基和受体之间的特定相互作用，这些相互作用可以被靶向改变G蛋白信号级联的初始事件。控制这些早期事件在治疗大量细胞信号相关疾病方面将是重要的。 与公共卫生相关：G蛋白调节大多数用于治疗人类疾病的细胞信号通路。这项研究将确定G蛋白信号中的新相互作用，这将成为新疗法的重要靶点。

DESCRIPTION (provided by applicant): More therapeutic drugs target G-protein-coupled receptors (GPCRs) than any other family of proteins. G proteins transduce signals initiated at the cell surface through interactions with GPCRs at the plasma membrane (PM). The long term objective of this research is to identify new G protein interactions that can serve as targets for novel therapeutic agents. G protein heterotrimers consist of alpha, beta, and gamma subunits. Upon G protein activation at the PM, the alpha subunit and beta-gamma dimer both activate downstream signaling cascades. Traditionally, both were thought to remain on the PM during this process. Recently, it was discovered that beta-gamma dimers can move off the PM and translocate to the Golgi and endoplasmic reticulum (ER), with targeting and rates that depend on the specific gamma subunit type. These findings call for a better understanding of the mechanisms behind the rapid and reversible movement of G protein subunits in live cells and its function in specifying a cell's response to stimulation of a GPCR. The gamma-dependent kinetics of beta-gamma translocation presents a unique tool for identifying specific G protein-receptor interactions that control translocation, as well as its physiological role. We will exploit these differential kinetics towards two specific aims. Aim 1: Test the hypothesis that interaction between the gamma subunit and the receptor is the primary regulator of receptor-stimulated G-beta-gamma translocation. Aim 2: Test the hypothesis that G-beta-gamma translocation to the endoplasmic reticulum (ER) targets inositol trisphosphate receptors and regulates calcium release. These experiments will test the evidence-based hypothesis that gamma subunits contribute to the specificity of G protein signaling by regulating movement of beta-gamma dimers throughout cell following activation of a GPCR. The findings from the experiments have the potential to identify specific interactions between gamma subunits and receptors that can be targeted to alter the initial events in G protein signaling cascades. Controlling these early events will be important in the treatment of a large number of cell signaling related diseases. PUBLIC HEALTH RELEVANCE: G proteins regulate most of the cell signaling pathways targeted in the treatment of human disease. This research will identify new interactions in G protein signaling that will be important targets for novel therapeutics.