Role of RGS Proteins in Opioid Addiction

 说明(申请人提供)：阿片类药物耐受性和依赖性的发展仍然是一个广泛的公共卫生问题。阿片类药物通过激活纹状体G蛋白偶联受体产生成瘾效应，从而导致信号通路的适应性变化。我们的长期目标是了解纹状体G蛋白活性的分子调节，因为它对控制药物成瘾很重要。最近的研究表明，G蛋白信号在细胞内被一系列被称为G蛋白信号调节因子(RGS)的蛋白失活。这为细胞提供了一种内在的机制，在滥用药物刺激受体的过程中调节信号，然而，人们对RGS在成瘾中的作用知之甚少。这项建议侧重于在阿片类药物耐受和依赖的形成过程中，纹状体必需的RGS蛋白对信号反应的分子调控。最近的研究表明，RGS7和RGS9-2在纹状体中结合相同的接头蛋白形成大分子复合体。这些RGS亚基的丰度对吗啡暴露很敏感，小鼠模型已经揭示了RGS复合亚单位在塑造对阿片类药物的行为反应方面的不同参与。综合我们的初步数据，我们假设RGS复合体在调节MOR信号中发挥重要作用，该信号门控对中央下游效应器腺苷环化酶的敏感性和第二信使cAMP的产生。这一假说将在两个相辅相成的目标中得到验证：1)了解阿片受体激活对腺苷环化酶-cAMP轴的适应以及RGS复合体在这一过程中的作用；2)表征RGS复合体中单个亚基在控制阿片信号转导中的机制作用。除了先进的基于细胞的分析外，我们的方法还将利用对来自多种遗传小鼠模型的活脑切片准备的光学评估。这些研究的结论将极大地扩展我们对阿片信号可塑性、RGS蛋白在成瘾中的作用以及对一种新的小鼠模型的评估的知识。

 DESCRIPTION (provided by applicant): The development of opioid tolerance and dependence continues to be a widespread public health concern. Opioids generate addictive effects by activating G protein coupled receptors in the striatum, which leads to adaptive changes in signaling pathways. Our long-term goal is to understand the molecular regulation of striatal G protein activity due to its importance for managing drug addiction. Recent work has revealed that G protein signaling is deactivated within the cell by a family of proteins termed Regulators of G protein Signaling (RGS). This provides the cell an intrinsic mechanism to modulate signaling during receptor stimulation by drugs of abuse, however little is known about the roles of RGS in addiction. This proposal is focused on the molecular regulation of signaling reactions by essential striatal RGS proteins during the development of opioid tolerance and dependence. Recent work has shown that RGS7 and RGS9-2 bind the same adapter proteins to form macromolecular complexes in the striatum. The abundance of these RGS subunits is sensitive to morphine exposure and mouse models have revealed the differential involvement of the RGS complex subunits in shaping behavioral responses to opioids. Collectively with our preliminary data, we hypothesize the RGS complex plays an essential role in regulating MOR signaling that gates sensitivity to the central downstream effector adenylate cyclase and the generation of the second messenger cAMP. This hypothesis will be tested in two complementary aims: 1) To understand adaptations in adenylate cyclase-cAMP axis in response to opioid receptor activation and the role of RGS complex in this process, 2) To characterize the mechanistic role of individual subunits in the RGS complex in controlling opioid signaling. Our approach will utilize optical assessment of live brain slice preparations from a multitude of genetic mouse models in addition to advanced cell-based assays. The conclusion of these studies will greatly expand our knowledge of opioid signaling plasticity, roles of RGS proteins in addiction, and evaluation of a novel mouse model.