Orphan Receptors in Regulation of Neuronal G Protein Signaling

 描述(申请人提供)：G蛋白偶联受体(GPCR)信号通路调节激素和神经递质的作用。它们对神经系统的正常功能是必不可少的，在许多神经精神和神经疾病中，它们经常被破坏和/或用于治疗目的。虽然我们了解了大量关于参与形成GPCR信号传递的分子成员的信息，但我们对信号调节机制的理解存在许多关键差距。GPCR域中最大的未知领域是“孤儿”受体的问题，即信号机制未知的GPCR样分子。人们普遍认为，孤儿受体具有巨大的潜力，可以发现神经系统的新生物学，并利用它来实现潜在的治疗效果。我们的长期目标是了解GPCR通路的组织和功能调节原理，以努力开发更好的脑部疾病治疗方法。我们关注的焦点是终止G蛋白信号转导的G蛋白信号转导蛋白(RGS)的调节蛋白，并越来越多地被视为GPCR通路中信号传递的调节中心。我们发现作为RGS家族的一员，RGS7在情绪调节中起着至关重要的作用。对其作用机制的研究发现，它控制着抑制G蛋白内向整流K+(GIRK)通道的活动，在大脑中，它与以前未描述的孤儿受体GPR158形成紧密的复合体。我们的初步数据表明，GPR158参与决定RGS7的活性、定位和表达，因此可能是一个重要的新的GPCR信号成分。有趣的是，在小鼠中，GPR158或RGS7基因敲除后，焦虑/抑郁相关行为显著减少。根据积累的初步数据，我们假设GPR158是G蛋白信号的关键调节因子，通过调节G蛋白的功能发挥作用 神经系统中的RGS7蛋白。这一假说将通过追求三个互补的特定目标来检验，这三个目标寻求：(1)确定GPR158调节RGS7催化活性的机制，(2)分析GPR158在控制RGS7在脑中的表达和定位中的作用，以及(3)确定GPR158对GIRK通道和神经元兴奋性的调节作用。为解决这些目标而提出的战略将需要生化、电生理和细胞生物学方法的协同组合，利用一系列强大的试剂和动物模型的存在。我们希望这些目标的实现将为哺乳动物的情绪调节提供关键的新见解，并为治疗干预的发展提供新的靶点。

 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.