Structure and Function of native kainate-type ionotropic glutamate receptor complexes

天然红藻氨酸型离子型谷氨酸受体复合物的结构和功能

• 批准号: 10696091
• 负责人: NAMI TAJIMA
• 金额: $ 40.25万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-05 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10696091
• 关键词: Alzheimer' s Disease; Brain; Brain Diseases; Cholesterol; Complex; Cryoelectron Microscopy; Development; Distant; Drug Targeting; Electrophysiology (science); Environment; Epilepsy; Exhibits; Functional disorder; Future; Glutamate Receptor; Homo; Huntington Disease; Kainic Acid Receptors; Learning; Ligands; Lipids; Major Depressive Disorder; Mediating; Memory; Modification; Molecular; Molecular Conformation; Mood Disorders; Neurons; Neuropilins; Physiological; Play; Post-Translational Protein Processing; Property; Proteins; Rattus; Regulation; Research; Resolution; Role; Schizophrenia; Signal Transduction; Structure; Synapses; Synaptic Transmission; Synaptic plasticity; autism spectrum disorder; cofactor; glutamatergic signaling; insight; interest; kainate; neural; neuronal excitability; neuropathology; neurotransmitter release; novel; novel therapeutic intervention; pharmacologic; postsynaptic; programs; receptor; receptor function; small molecule; therapy development; treatment strategy

PROJECT SUMMARY/ABSTRACT Neuronal ionotropic glutamate receptors (iGluRs) play key roles in mediating excitatory synaptic transmission in the brain and in a wide range of brain diseases, including Alzheimer’s and Huntington’s disease, schizophrenia, epilepsy, autism spectrum, major depression, and mood disorders. Glutamatergic signaling is pivotal for synaptic plasticity, learning, and memory formation. Kainate-type ionotropic glutamate receptors (KARs) are distributed throughout the brain and regulate the release of neurotransmitters and mediate excitatory synaptic transmission. KARs form homo- or hetero-tetramers composed of five homologous subunits of GluK1–5. Each subunit exhibits unique structural, functional, and pharmacological properties and subcellular localization. Moreover, misguided localization and dysfunction of KARs result in neuropathologies, therefore, KARs are a promising drug target. However, KARs are the least well understood group of iGluRs, and their molecular mechanisms remain elusive. The activities of neuronal KARs are regulated by pH, posttranslational modifications, lipid/cholesterol, and small molecules. Additionally, KAR function and localization are further modified by their auxiliary and accessory proteins. Thus, such brain lipids, modifications, and protein co-factors increase the diversity of KAR functional properties. The neuropilin and tolloid-like (NETO) auxiliary proteins, NETO1 and NETO2, are auxiliary proteins of KARs that are distantly homologous compared with auxiliary proteins associated with other iGluRs. How do such ligands and protein co-factors determine the gating of KARs and regulate synaptic signaling? How are the physiological brain lipid environment and posttranslational modifications contributing to receptor activities? To answer these questions, this proposed research will employ structural and electrophysiological approaches to develop our mechanistic understanding of the regulation of native postsynaptic GluK2/GluK5 KARs isolated from rat brains. The program will move forward in two major directions: In one project, I will determine high-resolution cryo-electron microscopy (cryo-EM) structures of native GluK2/GluK5 KARs in an activated state, but also in complex with ligands to capture multiple functional states. This will elucidate the conformational alternations of GluK2/GluK5 KARs by their ligands, which have not been well-observed in previously determined structures. Comparing our structures with other iGluRs will uncover how physiologically relevant heteromeric KARs are structurally and functionally distinct from other iGluR subfamilies. In a second concurrent project, we will elucidate the regulatory mechanisms of native KARs by NETO1 and NETO2 auxiliary proteins. Overall, our studies will provide fundamental insights into how neuronal KAR complexes are controlled by their ligands and auxiliary proteins, and how they mediate synaptic signaling, and thus neural activities. This information will facilitate the development of new therapeutic strategies for treating brain diseases.

项目总结/摘要 神经元离子型谷氨酸受体（iGluRs）在介导兴奋性突触传递中起关键作用， 脑和广泛的脑疾病，包括阿尔茨海默病和亨廷顿病，精神分裂症， 癫痫、自闭症谱系、严重抑郁症和情绪障碍。谷氨酸能信号传导是突触 可塑性、学习和记忆形成。红藻氨酸盐型离子型谷氨酸受体（KAR）分布于 在整个大脑和调节释放的神经递质和介导兴奋性突触传递。 KAR形成由GluK 1 -5的五个同源亚基组成的同源或异源四聚体。每个亚单位都表现出 独特的结构、功能和药理学特性以及亚细胞定位。此外，误导 KARs的定位和功能障碍导致神经病理学，因此，KARs是一个有前途的药物靶点。 然而，KAR是iGluRs中最不了解的一组，其分子机制仍然难以捉摸。 神经元KAR的活性受pH、翻译后修饰、脂质/胆固醇和小分子的调节。 分子。此外，KAR的功能和定位还通过其辅助和附件进行了进一步修改 proteins.因此，这种脑脂质、修饰和蛋白质辅因子增加了KAR功能性调节的多样性。 特性.神经纤毛蛋白和tolloid样（NETO）辅助蛋白NETO 1和NETO 2是辅助蛋白 与其他iGluR相关的辅助蛋白相比，KAR具有较远的同源性。怎么 这种配体和蛋白质辅因子决定KAR的门控和调节突触信号？们怎么样 生理脑脂质环境和翻译后修饰有助于受体活动？到 为了回答这些问题，这项拟议的研究将采用结构和电生理方法， 发展我们对分离的天然突触后GluK 2/GluK 5 KARs的调节机制的理解， 老鼠的大脑该计划将在两个主要方向前进：在一个项目中，我将确定高分辨率 低温电子显微镜（cryo-EM）结构的天然GluK 2/GluK 5 KAR在活化状态下，但也在 与配体络合以捕获多个功能状态。这将阐明的构象变化， GluK 2/GluK 5 KAR通过它们的配体，这在以前确定的结构中没有很好地观察到。 将我们的结构与其他iGluRs进行比较将揭示异聚KAR的生理相关性 在结构和功能上不同于其它iGluR亚家族。在第二个并行项目中，我们将 阐明NETO 1和NETO 2辅助蛋白对天然KAR的调控机制。总的来说，我们的 这些研究将为神经元KAR复合物如何受其配体控制提供基本的见解， 辅助蛋白，以及它们如何介导突触信号，从而神经活动。这些信息将 促进开发治疗脑部疾病的新治疗策略。