Orphan Receptors in Regulation of Neuronal G Protein Signaling

 描述（由申请人提供）：G蛋白偶联受体（GPCR）信号通路介导激素和神经递质的作用。它们对于神经系统的正常功能是必不可少的，并且在许多神经精神和神经病症中经常被破坏和/或用于治疗目的。虽然我们了解了大量有关参与塑造GPCR信号传递的分子参与者的信息，但我们对信号调节机制的理解存在许多关键空白。GPCR领域最大的未知领域之一是“孤儿”受体，具有未知信号传导机制的GPCR样分子。人们普遍认为，孤儿受体在揭示神经系统的新生物学和利用它获得潜在的治疗益处方面具有巨大的潜力。我们的长期目标是了解GPCR途径的组织和功能调节原理，以努力开发更好的脑疾病治疗方法。 我们关注的焦点是G蛋白信号传导调节因子（Regulators of G protein Signaling，RGS）蛋白，它终止G蛋白信号传导，并且越来越多地被视为GPCR途径中信号传递的调节中心。我们发现RGS 7是RGS家族的一员，在情绪调节中起着重要的作用。对其作用机制的研究表明，它控制抑制性G蛋白抑制性整流K+（GIRK）通道的活性，并且在大脑中，它与先前未表征的孤儿受体GPR 158形成紧密复合物。我们的初步数据表明，GPR 158参与决定RGS 7的活性，定位和表达，因此可能代表一个重要的新GPCR信号组分。有趣的是，在小鼠中敲除GPR 158或RGS 7导致焦虑/抑郁相关行为的显著减少。 基于积累的初步数据，我们假设GPR 158是G蛋白信号传导的关键调节剂，其通过调节 RGS 7蛋白在神经系统中的作用该假设将通过追求三个互补的特定目的进行测试，这些目的旨在：（1）确定GPR 158调节RGS 7催化活性的机制，（2）分析GPR 158在控制RGS 7在脑中的表达和定位中的作用，以及（3）确定GPR 158对GIRK通道和神经元兴奋性调节的贡献。为解决这些目标而提出的策略将需要生物化学、电生理学和细胞生物学方法的协同组合，利用存在的一系列强大的试剂和动物模型。我们希望这些目标的实现将为哺乳动物的情绪调节提供重要的新见解，并为开发治疗干预措施提供新的靶点。

 DESCRIPTION (provided by applicant): G protein coupled receptor (GPCR) signaling pathways mediate actions of hormones and neurotransmitters. They are essential for normal function of the nervous system and are frequently disrupted, and/or exploited for therapeutic purposes, in many neuropsychiatric and neurological conditions. While we learned considerable information about molecular players involved in shaping GPCR signal transmission there are many critical gaps in our understanding of mechanisms pertaining to signaling regulation. Among biggest uncharted territories in GPCR field is an issue of "orphan" receptors, GPCR-like molecules with unknown signaling mechanisms. It is generally recognized that orphan receptors have tremendous potential for uncovering novel biology of the nervous system and harnessing it for potential therapeutic benefits. Our long- term goal is to understand principles for organizatio and functional regulation of GPCR pathways in the effort to develop better treatments for brain disorders. The focus of our attention is on the Regulators of G protein Signaling (RGS) proteins that terminate G protein signaling and are increasingly viewed as regulatory hubs for signal transmission in the GPCR pathways. We have found that a member of RGS family, RGS7 plays essential role in mood regulation. Investigating the mechanisms of its action revealed that it controls the activity of the inhibitory G protein Inwardly rectifying K+ (GIRK) channels and that i the brain it forms tight complexes with previously uncharacterized orphan receptor, GPR158. Our preliminary data suggest that GPR158 is involved in determining activity, localization and expression of RGS7 and thus may represent an essential new GPCR signaling component. Intriguingly, knockout of either GPR158 or RGS7 in mice results in a prominent reduction in anxiety/depression-related behaviors. Based on accumulated preliminary data we hypothesize that GPR158 is the critical regulator of G protein signaling that act by modulating the function of RGS7 proteins in the nervous system. This hypothesis will be tested by pursuing three complementary Specific Aims that seek to: (1) determine mechanisms, by which GPR158 regulates catalytic activity of RGS7, (2) analyze the role of GPR158 in controlling expression and localization of RGS7 in the brain and (3) determine contribution of GPR158 to regulation of GIRK channels and neuronal excitability. The strategy proposed to address these Aims will entail a synergistic combination of biochemical, electrophysiological and cell-biological approaches, exploiting the existence of a powerful array of reagents and animal models. We hope that accomplishment of these goals will provide critical new insights into the mood regulation in mammals and suggest novel targets for the development of therapeutic interventions.