RGS9-2 Protein: Novel Partners and Functional Roles

描述（由申请人提供）：RGS （G蛋白信号调节因子）蛋白通过G蛋白信号通路调节转导到细胞中的信息。已经确定了大约30个rgs。所有这些蛋白质都含有一个高度保守的RGS结构域，但不同之处在于存在额外的蛋白质-蛋白质相互作用基序，这些基序被认为是与信号伙伴指定相互作用的基序。这些基序的存在和排列定义了几个不同的RGS蛋白家族。RGS9-2是一组RGS蛋白的脑特异性成员，通过4个蛋白-蛋白相互作用结构域的串联排列可识别，即disheveled egllO， pjeckstrin （DEP）结构域，G-gamma-样（GGL）结构域，G蛋白信号传导调节（RGS）结构域和c端富含脯氨酸的结构域。该蛋白在中枢神经系统中具有显著的分布，仅在纹状体中有非常高的表达水平，在发育过程中，也在大脑皮层中表达。这种分布表明RGS9-2在这些区域调节G蛋白信号传导的特定方面发挥作用，因此在神经精神疾病的病理生理学中具有潜在作用。事实上，RGS9-2已被证明在帕金森病中增加，并促进对阿片类药物的耐受性。不幸的是，目前对RGS9-2在大脑中的具体功能知之甚少。为了了解RGS9-2在细胞/分子水平上的作用，我们的实验室专注于鉴定该蛋白的特定信号伙伴。利用酵母双杂交筛选和共免疫沉淀技术，我们发现RGS9-2与a-actin -2之间存在强相互作用。A -actin -2最广为人知的作用之一是调节NMD - A受体脱敏。与RGS9-2和a- actiin -2相互作用的生理作用一致，在初步研究中，我们发现RGS9-2对NMD -a电流有很强的调节作用。综上所述，这些结果表明RGS9-2在中央前脑神经元中具有一种新颖的、潜在的非常令人兴奋的作用。在目前的应用中，我们建议通过解决以下三个问题来扩展这些初步观察结果：1)RGS9-2和a-actin -2内哪些特定区域对它们的相互作用至关重要；2)RGS9-2和a-actin -2在大脑中是否共定位；3)RGS9-2和a-actin -2之间的相互作用对NMDA受体功能是否具有功能意义。为了回答这些问题，我们提出以下目标：确定介导rgs9 -2和a-actin -2相互作用的最关键区域，并确定这种相互作用的功能相关性。具体目标2。目的探讨RGS9-2与a-actin -2在中枢神经元中的物理和功能相互作用。

DESCRIPTION (provided by applicant): RGS (Regulators of G protein Signaling) proteins modulate the information transduced into cells through G protein signaling pathways. Approximately thirty RGSs have been identified. All of these proteins contain a highly conserved RGS domain, but differ in the presence of additional protein-protein interaction motifs that are thought to specify interactions with signaling partners. The presence and arrangement of these motifs defines several distinct families of RGS proteins. RGS9-2 is a brain-specific member of a group of RGS proteins identifiable by the tandem arrangement of 4 protein- protein interaction domains, namely a Dishevelled egllO, pjeckstrin (DEP) domain, a G-gamma-like (GGL) domain, a Regulator of G protein signaling (RGS) domain, and a C-terminal proline-rich domain. This protein exhibits a remarkable distribution in the central nervous system, with very high levels of expression only in the striatum, and during development, also in the cerebral cortex. This distribution suggests a role for RGS9-2 in regulating specific aspects of G protein signaling in these regions, and hence a potential role in the pathophysiology of neuropsychiatric disorders. In fact, RGS9-2 has been shown to be increased in Parkinson's disease and to facilitate tolerance to opioids. Unfortunately, little is known at the present time about the specific function(s) of the RGS9-2 in the brain. In an effort to understand the role of RGS9-2 at a cellular/molecular level, our laboratory has focused on the identification of specific signaling partners for this protein. Using yeast two hybrid screen and co- immunoprecipitation techniques, we have identified a strong interaction between RGS9-2 and a-actinin-2. One of the best understood roles for a-actinin-2 is in the regulation of NMD A receptor desensitization. Consistent with a physiological role for the interaction between RGS9-2 and a-actinin-2, in preliminary studies we have uncovered a strong regulation of NMD A currents by RGS9-2. Combined, these results suggest a novel and potentially very exciting role for RGS9-2 in central forebrain neurons. In the present application, we propose to extend these preliminary observations by addressing these three questions: 1) what specific regions within RGS9-2 and a-actinin-2 are critical for their mutual interaction, 2) do RGS9-2 and a-actinin-2 colocalize in the brain, 3) does the interaction between RGS9-2 and a-actinin-2 have functional significance for NMDA receptor function. To answer these questions, we propose the following aims: Specific Aim 1. To identify the regions most critical in mediating the interaction ofRGS9-2 and a-actinin-2, and to determine the functional relevance of this interaction. Specific Aim 2. To assess the physical and functional interaction between RGS9-2 and a-actinin-2 in central neurons.