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

描述（由申请人提供）：与其他蛋白家族相比，更多的治疗药物靶向g蛋白偶联受体（gpcr）。G蛋白通过与质膜上的gpcr相互作用转导细胞表面启动的信号。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γ亚基组成。当G蛋白在PM处激活时，α亚基和β二聚体都激活下游信号级联反应。传统上，两人都被认为在这一过程中会继续担任总理。最近，人们发现β - γ二聚体可以从PM转移到高尔基体和内质网（ER），其靶向和速率取决于特定的γ亚基类型。这些发现要求更好地理解活细胞中G蛋白亚基快速可逆运动的机制及其在指定细胞对GPCR刺激的反应中的功能。β - γ易位的γ依赖动力学提供了一种独特的工具，用于识别控制易位的特定G蛋白-受体相互作用及其生理作用。我们将利用这些微分动力学来达到两个特定的目的。目的1：验证γ亚基和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转运到内质网（ER）靶向肌醇三磷酸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，即伽马亚基通过在GPCR激活后调节β - γ二聚体在细胞中的运动来促进G蛋白信号传导的特异性。实验结果有可能确定γ亚基和受体之间的特定相互作用，可以靶向改变G蛋白信号级联中的初始事件。控制这些早期事件对于治疗大量细胞信号相关疾病非常重要。

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.