Structural Basis of Signal Instigation Through Family C GPCRs

通过 C 族 GPCR 激发信号的结构基础

• 批准号: 10456480
• 负责人: Georgios Skiniotis
• 金额: $ 5.84万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-15 至 2026-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10456480
• 关键词: Address; Agonist; Binding; Binding Proteins; Binding Sites; Biochemical; Biological Assay; Cell membrane; Central Nervous System Diseases; Clams; Communication; Complement; Complex; Coupled; Couples; Coupling; Cryoelectron Microscopy; Cysteine-Rich Domain; Defect; Detergents; Disease; Drug Addiction; Environment; Extracellular Domain; Family; Functional disorder; G Protein-Coupled Receptor Signaling; G-Protein-Coupled Receptors; GRM5 gene; GTP-Binding Proteins; Glutamates; Heterotrimeric GTP-Binding Proteins; Knowledge; Length; Ligand Binding; Link; Lipids; Maps; Membrane; Mental Depression; Metabotropic Glutamate Receptors; Micelles; Molecular; Molecular Conformation; Mutagenesis; Mutation; Nerve Degeneration; Neuraxis; Neurologic; Pain; Parkinson Disease; Pharmacology; Phospholipids; Physiological; Preparation; Property; Proteins; Protomer; Receptor Activation; Resolution; Role; Schizophrenia; Side; Signal Transduction; Site; Specificity; Structure; Synaptic Transmission; Synaptic plasticity; System; Testing; Transmembrane Domain; Venus; Work; combat; computer studies; conformational conversion; design; dimer; drug discovery; extracellular; fly; gamma-Aminobutyric Acid; in vitro Assay; insight; metabotropic glutamate receptor 2; molecular dynamics; nanodisk; neuronal excitability; neuropsychiatry; neurotransmission; novel therapeutic intervention; protein activation; protein complex; receptor; receptor coupling; receptor function; release of sequestered calcium ion into cytoplasm; therapeutic target

Abstract The γ-aminobutyric acid B receptor (GABABR) and the metabotropic glutamate receptors (mGluRs) belong to the Family C of G protein coupled receptors (GPCRs) and critically regulate neuronal excitability, synaptic transmission and plasticity. Many disorders of the CNS have been linked to alterations in neuronal excitability via the glutamatergic and GABAergic system. Accordingly, mGluRs and GABABR have been the subject of an enormous drug discovery effort as they represent major therapeutic targets for treating numerous physiological dysfunctions and for neurodegenerative and neuropsychiatric conditions. Apart from the prototypical seven transmembrane helix (7TM) domain, Family C GPCRs also include a large extracellular ‘venus fly trap’ (VFT) domain that constitutes the orthosteric ligand binding site. Binding of ligand to the extracellular VFT domain triggers a large conformational change in the VFT domains from an open to a closed conformation. This clam- shell like closure of the extracellular domain results in receptor engagement and activation of G proteins on the intracellular side of the transmembrane domain with a mechanism that remains unclear. Receptor activated G proteins then act to either enhance or repress secondary messenger signaling cascades. We recently showed cryoEM structures of near-full length mGluR5 and GABABR in inactive and active conformations, revealing extensive transitions in the organization of the 7TM dimer upon ligand binding to the VFT. Notwithstanding this progress, several key questions remain regarding the allosteric communication across the cell membrane by Family C GPCRs, and particularly the mechanism of G protein coupling and activation. To address these questions, we propose to obtain the structures of mGluR2, mGluR5 and GABABR in complex with their cognate G proteins and probe the structural insights using molecular dynamics simulations and mutagenesis coupled to functional assays. The similarities and differences amongst these receptor-G protein complexes will allow us to contrast and compare our findings and examine aspects of G protein coupling and selectivity. Collectively, these studies will enable us to create a detailed mechanistic framework to understand Family C GPCR signaling and will form the basis for the design of novel therapeutic strategies targeting these receptors.

抽象的 γ-氨基丁酸 B 受体 (GABABR) 和代谢型谷氨酸受体 (mGluRs) 属于 G 蛋白偶联受体 (GPCR) 家族 C 并严格调节神经元兴奋性、突触 传输性和可塑性。许多中枢神经系统疾病与神经元兴奋性的改变有关 通过谷氨酸能和 GABA 能系统。因此，mGluR 和 GABABR 已成为研究的主题 巨大的药物发现工作，因为它们代表了治疗许多生理疾病的主要治疗靶点 功能障碍以及神经退行性和神经精神疾病。除了典型的七 跨膜螺旋 (7TM) 结构域，C 家族 GPCR 还包括一个大型细胞外“捕蝇器”(VFT) 构成正位配体结合位点的结构域。配体与细胞外 VFT 结构域的结合 触发 VFT 结构域从开放构象到闭合构象的巨大构象变化。这蛤蜊—— 细胞外结构域的壳状闭合导致受体结合并激活 G 蛋白 跨膜结构域的细胞内侧，其机制仍不清楚。受体激活G 然后蛋白质起到增强或抑制第二信使信号级联反应的作用。我们最近展示了 近全长 mGluR5 和 GABABR 处于非活性和活性构象的冷冻电镜结构，揭示了 配体与 VFT 结合后，7TM 二聚体的组织发生了广泛的转变。尽管如此 尽管取得了进展，但关于跨细胞膜变构通讯的几个关键问题仍然存在 C 族 GPCR，特别是 G 蛋白偶联和激活的机制。为了解决这些 问题，我们建议获得 mGluR2、mGluR5 和 GABABR 及其同源复合物的结构 G 蛋白并使用分子动力学模拟和诱变来探索结构见解 功能测定。这些受体-G 蛋白复合物之间的相似性和差异将使我们能够 对比和比较我们的发现并检查 G 蛋白偶联和选择性的各个方面。总的来说， 这些研究将使我们能够创建一个详细的机制框架来理解 C 族 GPCR 信号传导并将成为设计针对这些受体的新型治疗策略的基础。