Orphan Receptors in Regulation of Neuronal G Protein Signaling

项目总结 G蛋白偶联受体(GPCR)信号通路介导激素和 神经递质。它们对神经系统的正常功能是必不可少的，在许多情况下经常被破坏 神经精神和神经疾病和/或被用于治疗目的。当我们了解到 关于传统GPCR信号转导中涉及的分子成员的大量信息，许多关键差距 留下来。在该领域最大的未知领域中，有一个“孤儿”GPCRs的问题，即具有 未知的信号机制。人们普遍认为，孤儿受体具有巨大的潜在作用 发现神经系统的新生物学，并利用它获得潜在的治疗益处。我们的长- 学期目标是理解探索不足的GPCR的组织和功能调节的原则 努力开发更好的脑部疾病治疗方法的途径。 我们关注的焦点是鲜为人知的孤儿受体-GPR158，但它是目前研究最多的 大脑中有丰富的GPCRs。我们发现GPR158在应激诱导的抑郁中起着关键作用。它的 糖皮质激素诱导其表达，在严重抑郁障碍患者中表达上调。 相反，在小鼠中消除GPR158会产生显著的抗抑郁表型和压力弹性。在… 在分子水平上，GPR158将G蛋白信号负调控因子RGS7招募到质膜上 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GPR158生物学理解中的两个最大空白：它的激活 影响情绪状态下神经回路的效应器的机制和特性。 有趣的是，我们的初步数据揭示了GPR158细胞外与细胞相互作用的网络- 粘附性类似于蛋白质，表明cAMP调节的K+通道复合体可能是一种信号媒介。 根据积累的初步数据，我们假设GPR158传递由 细胞外结合伙伴通过参与抑制性离子通道复合体来改变神经元的兴奋性。 这一假设将通过追求三个相辅相成的具体目标来检验，这三个目标寻求：(1)确定 GPR158传递其信号的分子机制，(2)剖析依赖GPR158的电路 (3)探讨K+通道复合体在中枢神经系统中的作用。 GPR158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协同增效 生化、电生理和细胞生物学方法的结合，利用 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批判性新见解，并为发展新的靶点提出了建议 治疗性干预。

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.