Mechanisms of Adhesion GPCR Action

摘要/摘要： G蛋白偶联受体(GPCRs)通过细胞传递化学或激素刺激的信息。 膜激活异三聚体G蛋白，从而引起生理/细胞反应。附着力G 蛋白偶联受体(AGPCRs)是由33个成员组成的GPCRs亚家族，现已成为 由于对这些受体在其中的作用的了解不断扩大，因此成为密集研究的对象 发育障碍和成人癌症。尽管进行了密集的研究，但杂三聚体的直接测量 直到我们最近的工作之前，任何aGPCR家族成员都从未激活过G蛋白。我们 利用我们开发的一项新技术来纯化大量的所有类别的杂三聚体G 两个粘附性GPCRs介导的蛋白α亚基及其成功重组的G蛋白激活 (GPR56和GPR110)。我们确定了GPR56和GPR110激活并发现的G蛋白亚型 两种受体的胞外片段都抑制了受体部分的G蛋白激活活性 它嵌入在膜(TM或跨膜结构域)中。当受体激活时， 抑制性胞外片段从TM结构域解离，可能是由于蛋白质配体的作用 与之结合的细胞外空间。这一行为揭开了作用于其自身的TM域的一小部分 以积极的调控方式(受束缚的激动剂)。这些初步数据使我们提出，整个 黏附GPCR类在受拴系激动剂的调节方面具有共同的作用机制。我们 寻求验证GPR56、GPR114和第六类附着力GPCR的机制，并执行详细的 研究确定拴系激动剂的确切组成以及它与TM结构域结合的方式。 我们将进行研究，以调查受体的天然配体如何作用于揭示束缚 激动剂，同时我们从分子上识别真正的受体配体。小分子化学文库的筛选 将进行合成粘附性GPCR调节剂的鉴定。这些化合物将极大地帮助我们 作为研究工具的机械学研究，可能会被用来阻止脑血管疾病的病理生理作用 疾病背景下的粘附性GPCR。了解粘附性GPCRs的作用机制是一项重要的工作 这是开发治疗归因于这一GPCR类疾病的越来越多的疾病所必需的。 我们的工作致力于阐明黏附GPCR的作用机制。

Summary/Abstract: G protein Coupled Receptors (GPCRs) transduce information from chemical or hormonal stimuli across the cell membrane to activate heterotrimeric G proteins and thereby elicit physiological/cellular responses. Adhesion G Protein Coupled Receptors (aGPCRs) comprise a 33-member sub-family of GPCRs that have become subjects of intense investigation due to an expanding understanding of the roles these receptors have in developmental disorders and adult cancers. Despite the intense study, direct measurements of heterotrimeric G protein activation by any aGPCR family member had never been made until our very recent work. We leveraged a new technology that we developed to purify large quantities of all classes of heterotrimeric G protein α subunits and successfully reconstituted G protein activation mediated by two adhesion GPCRs (GPR56 and GPR110). We determined the G protein subtypes that GPR56 and GPR110 activate and found that the extracellular fragments of both receptors inhibit the G protein activating activity of the receptor portion that is intercalated in the membrane (TM or Trans-membrane domain). Receptor activation occurs when the inhibitory extracellular fragment is dissociated from the TM domain, perhaps by the action of protein ligands in the extracellular space that bind to it. This act unmasks a short portion of the TM domain that acts upon itself in positive regulatory fashion (a tethered agonist). These preliminary data lead us to propose that the entire adhesion GPCR class shares a common mechanism of action in being regulated by tethered agonists. We seek to verify the mechanism for GPR56, GPR114, and the Group VI adhesion GPCRs and perform detailed studies to define the exact composition of the tethered agonist and the way that it engages the TM domain. We will conduct studies to investigate the way that natural ligands of the receptors act to reveal the tethered agonist while we molecularly identify authentic receptor ligands. Screens of small molecule chemical libraries will be conducted to identify synthetic adhesion GPCR modulators. These compounds will greatly aid our mechanistic studies as research tools and may find use as leads to block the pathophysiologic actions of adhesion GPCRs in disease contexts. Understanding the mechanism of action of adhesion GPCRs is a pre- requisite to the development of therapies for the increasing number of diseases ascribed to this GPCR-class. Our work strives to elucidate the mechanism of adhesion GPCR action.