Mechanism of functional modulation of glutamate receptors by their auxiliary subunits

谷氨酸受体辅助亚基的功能调节机制

• 批准号: 10536674
• 负责人: Terunaga Nakagawa
• 金额: $ 39.63万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-12-15 至 2025-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10536674
• 关键词: AMPA Receptors; Adopted; Agonist; Alanine; Alzheimer' s Disease; Architecture; Brain; Characteristics; Cognition; Complex; Cryoelectron Microscopy; Data; Detergents; Diameter; Drug Targeting; Electrophysiology (science); Environment; Ethane; Exposure to; Glutamate Agonist; Glutamate Receptor; Glutamates; Goals; Hippocampus; Human; Ion Channel; Ion Channel Gating; Kinetics; Knowledge; Learning; Ligands; Limbic Encephalitis; Lipid Bilayers; Lipids; Liquid substance; Measurement; Mediating; Memory; Mental disorders; Missense Mutation; Modeling; Molecular; Molecular Conformation; Mutate; Mutation; Neurotransmitters; Outcome; Outcome Study; Physiological; Play; Preparation; Regulation; Resolution; Role; Seizures; Shapes; Side; Signal Transduction; Specimen; Stroke; Structure; Synapses; Synaptic Transmission; Synaptic plasticity; Testing; Therapeutic; Time; autism spectrum disorder; conflict resolution; desensitization; experimental study; inhibitor; insight; mimetics; mutant; nanodisk; nervous system disorder; neurotransmission; neurotransmitter release; novel therapeutics; pharmacologic; rational design; receptor; receptor function; reduce symptoms; response; trafficking

PROJECT SUMMARY The AMPA type ionotropic glutamate receptors (AMPARs) are ligand gated ion channels activated by the neu- rotransmitter glutamate. They mediate the majority of excitatory neurotransmission in the brain and the signals transduced by these complexes are critical for synaptic plasticity, learning and memory. AMPAR auxiliary sub- units regulate trafficking and gating modulation of AMPARs. In this proposal we will investigate the mechanism of AMPAR regulation by their auxiliary subunits. The core AMPAR auxiliary subunits are TARPs, GSG1L, and cornichons (CNIHs). The TARPs are extensively studied and therapeutic compounds to alleviate seizure are already available to target hippocampus enriched TARP gamma-8. GSG1L is a negative modulator of AM- PARs, while TARPs and CNIHs serve as positive modulators. In humans, various residues located at the inter- action interface between AMPAR and auxiliary subunits are intolerant to missense mutations, indicating their critical roles in brain function. We hypothesize that different auxiliary subunits can co-assemble with the chan- nel and produce a rich variety of gating modulations, which are fundamental in regulating synaptic transmission and plasticity. To establish the structural and mechanistic basis, we will study complex AMPAR assemblies that have high physiological relevance. In Aim 1 we hypothesize that fine structural differences among AMPAR assemblies are fundamental for producing characteristic gating modulation and propose to reveal the architec- tures of heterotetrameric AMPARs containing up to two types of auxiliary subunits at different functional states in detergent using cryo-EM. By comparing the structures, new mechanistic models that could explain how aux- iliary subunits control the time course and magnitude of gating are likely to emerge, which will be validated us- ing electrophysiology. Next, currently available cryo-EM structures revealed the presence of lipids surrounding the complex. We hypothesize that these lipids play important function in AMPAR gating modulation, which will be tested in Aim2. Finally, we suggest that AMPAR/auxiliary subunit complex prepared in near physiological conditions void of detergent must be studied to build more precise mechanistic models of its allosteric gating modulation. In Aim 3, we propose to solve high resolution cryo-EM structures of AMPAR/auxiliary subunit complex embedded in a lipid bilayer mimetic environment to resolve the known discrepancies between struc- tures obtained in detergent and electrophysiology data. The role of auxiliary subunits in tuning ion channel gat- ing kinetics is predicted to have significant impact on circuit dynamics. In summary, the outcomes of this study are expected to advance our mechanistic understanding of AMPAR function and assist developing new thera- peutic compounds that can alleviate dysregulation of AMPARs seen in neurological and psychiatric disorders, such as Alzheimer’s disease, stroke, autism, Rasmussen’s and limbic encephalitis, and seizure.

项目概要 AMPA 型离子型谷氨酸受体 (AMPAR) 是由神经激活的配体门控离子通道 它们介导大脑中的大部分兴奋性神经传递和信号。 这些复合物的转导对于突触可塑性、学习和记忆至关重要。 在本提案中，我们将研究该机制。 AMPAR 的核心辅助亚基是 TARP、GSG1L 和 主要研究了 TARP 和缓解癫痫发作的治疗化合物。 GSG1L 已可用于靶向海马体富集的 TARP gamma-8，它是 AM- 的负调节剂。 PAR、​​TARP 和 CNIH 在人类中充当正调节剂，各种残基位于中间。 AMPAR 和辅助亚基之间的作用界面不能容忍错义突变，表明它们 我们发现不同的辅助亚基可以与通道共同组装。 nel 并产生丰富多样的门控调制，这是调节突触传递的基础 为了建立结构和机械基础，我们将研究复杂的 AMPAR 组件。 在目标 1 中，我们追求 AMPAR 之间的精细结构差异。 组件是产生特征选通调制的基础，并建议揭示架构- 含有多达两种不同功能状态的辅助亚基的异四聚体 AMPAR 的结构 通过比较结构，新的机械模型可以解释辅助-电镜的作用。 髂亚基控制可能出现的门控的时间过程和幅度，这将得到验证 接下来，目前可用的冷冻电镜结构揭示了周围脂质的存在。 我们认为这些脂质在 AMPAR 门控调节中发挥重要作用，这将 最后，我们建议在接近生理的情况下制备AMPAR/辅助亚基复合物。 必须研究没有清洁剂的条件，以建立其变构门控的更精确的机械模型 在目标 3 中，我们建议解决 AMPAR/辅助亚基的高分辨率冷冻电镜结构。 复合物嵌入脂质双层模拟环境中，以解决结构之间的已知差异 在洗涤剂和电生理学数据中获得的结果辅助亚基在调节通道门方面的作用。 总而言之，本研究的结果预计会对电路动力学产生重大影响。 预计将增进我们对 AMPAR 功能的机制理解并协助开发新的治疗方法 可以缓解神经和精神疾病中 AMPAR 失调的天然化合物， 例如阿尔茨海默氏病、中风、自闭症、拉斯穆森氏病和边缘脑炎以及癫痫发作。