Orphan Receptors in Regulation of Neuronal G Protein Signaling

项目摘要 G蛋白偶联受体（GPCR）信号传导途径介导激素的作用， 神经传递素它们对神经系统的正常功能至关重要，在许多情况下经常受到干扰。 神经精神和神经系统疾病和/或用于治疗目的。当我们了解到 关于参与传统GPCR信号传导的分子参与者的大量信息， 保持。该领域最大的未知领域之一是“孤儿”GPCR问题，即具有 未知的信号机制普遍认为孤儿受体具有巨大的潜力， 揭示神经系统的新生物学，并利用它来获得潜在的治疗益处。我们长久以来- 长期目标是了解组织和功能调节的原则，探索不足的GPCR 在努力开发更好的治疗大脑疾病的途径。 我们关注的焦点是对孤儿受体-GPR 158的了解很少，但它是最重要的受体之一。 大脑中有丰富的GPCR。我们发现GPR 158在应激诱导的抑郁症中起着关键作用。其 表达由糖皮质激素诱导并在重度抑郁症患者中上调。 相反，小鼠中的GPR 158消除产生显著的抗抑郁表型和应激恢复力。在 在分子水平上，GPR 158将G蛋白信号负调节因子RGS 7募集到质膜上 影响第二信使cAMP的产生以控制突触传递和神经元兴奋性。 该提案的重点是填补我们对GPR 158生物学理解中的两个最大空白： 机制和身份的效应介导其影响的神经元回路的情感状态。 有趣的是，我们的初步数据揭示了GPR 158与细胞的细胞外相互作用网络， 粘附样蛋白，并指出cAMP调节的K+通道复合物作为可能的信号介质。 基于积累的初步数据，我们假设GPR 158转导由以下触发的信号： 细胞外结合伴侣通过接合抑制性离子通道复合物而改变神经元兴奋性。 这一假设将通过追求三个互补的具体目标来检验，这些目标旨在：（1）确定 GPR 158转导其信号的分子机制，（2）剖析依赖GPR 158的电路 作用，发挥行为效应和（3）探测K+通道复合体介导的参与， GPR 158对神经元兴奋性的影响。为实现这些目标而提出的战略将需要一个协同的 生物化学、电生理学和细胞生物学方法的组合，利用 一系列强大的技术和动物模型。我们希望，这些目标的实现将提供 对哺乳动物情绪调节的重要新见解，并为开发 治疗干预。

PROJECT SUMMARY G protein coupled receptor (GPCR) signaling pathways mediate actions of hormones and neurotransmitters. They are essential for normal function of the nervous system, frequently disrupted in many neuropsychiatric and neurological conditions and/or exploited for therapeutic purposes. While we learned considerable information about molecular players involved in traditional GPCR signaling, many critical gaps remain. Among biggest uncharted territories in the field is an issue of “orphan” GPCRs, receptors 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 in organization and functional regulation of poorly explored GPCR pathways in the effort to develop better treatments for brain disorders. The focus of our attention is on poorly understood orphan receptor- GPR158, yet one of the most abundant GPCRs in the brain. We found that GPR158 plays a pivotal role in stress-induced depression. Its expression is induced by glucocorticoids and is upregulated in patients with major depressive disorder. Conversely, GPR158 elimination in mice produces marked anti-depressant phenotype and stress resilience. At the molecular level, GPR158 recruits negative regulator of G protein signaling, RGS7 to the plasma membrane impacting production of the second messenger cAMP to control synaptic transmission and neuronal excitability. The proposal is focused on filling two biggest gaps in our understanding of GPR158 biology: its activation mechanisms and identity of effectors mediating its effects on neuronal circuitry underlying affective states. Intriguingly, our Preliminary Data revealed network of GPR158 extracellular interactions with the cell- adhesion like proteins and pointed to a cAMP-modulated K+ channel complex as a possible signaling mediator. Based on accumulated preliminary data we hypothesize that GPR158 transduces signals triggered by extracellular binding partners into changes of neuronal excitability by engaging inhibitory ion channel complex. This hypothesis will be tested by pursuing three complementary Specific Aims that seek to: (1) determine molecular mechanisms by which GPR158 transduces its signals, (2) dissect circuits that rely on GPR158 action to exert behavioral effects and (3) probe the involvement of the K+ channel complex in mediating the effect of GPR158 on 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 technologies 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.