Role of RGS Proteins in Opioid Addiction

 描述（由申请人提供）：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中的G蛋白偶联受体产生成瘾作用，这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，因为它对管理药物成瘾很重要。最近的研究表明，G蛋白信号在细胞内被称为G蛋白信号调节因子（Regulators of G protein Signaling，RGS）的蛋白质家族灭活。这为细胞提供了一种内在机制，在滥用药物的受体刺激期间调节信号传导，然而对RGS在成瘾中的作用知之甚少。该建议的重点是在阿片耐受性和依赖性的发展过程中，通过必要的纹状体RGS蛋白的信号反应的分子调控。最近的研究表明，RGS 7和RGS 9 -2结合相同的衔接蛋白，在纹状体中形成大分子复合物。这些RGS亚基的丰度对吗啡暴露敏感，并且小鼠模型已经揭示了RGS复合物亚基在形成对阿片类药物的行为反应中的差异参与。综合我们的初步数据，我们假设RGS复合物在调节莫尔信号传导中起重要作用，MOR信号传导控制对中枢下游效应物腺苷酸环化酶的敏感性和第二信使cAMP的产生。这一假设将在两个互补的目的进行测试：1）了解腺苷酸环化酶-cAMP轴响应阿片受体激活的适应性以及RGS复合物在此过程中的作用，2）表征RGS复合物中单个亚基在控制阿片信号传导中的机制作用。我们的方法将利用光学评估的活脑切片制剂从众多的遗传小鼠模型，除了先进的细胞为基础的测定。这些研究的结论将大大扩展我们对阿片信号可塑性，RGS蛋白在成瘾中的作用以及新型小鼠模型评估的认识。

 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.