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.

项目摘要 AMPA型离子型谷氨酸受体（AMPARS）是配体门控离子通道，由neu-激活 旋转石谷氨酸。他们介导大脑中的大多数兴奋神经传递和信号 这些复合物转导的转导对于突触可塑性，学习和记忆至关重要。 AMPAR辅助子 单位调节AMPAR的贩运和门控调制。在此提案中，我们将调查机制 通过其辅助亚基的AMPAR调节。核心AMPAR辅助亚基是防水布，GSG1L和 Cornichons（CNIHS）。篷布是广泛研究的，可以减轻癫痫发作的治疗化合物 已经可用于靶向海马富含防水布伽玛-8。 GSG1L是AM-的负调节剂 PARS，而TARPS和CNIHS充当正调节剂。在人类中，各种残差位于 AMPAR和辅助亚基之间的动作接口对错义突变不宽，表明它们 在大脑功能中的关键作用。我们假设不同的辅助亚基可以与木 NEL并产生各种各样的门控调制，这对于调节突触传播至关重要 和可塑性。为了建立结构和机械基础，我们将研究复杂的AMPAR组件 具有很高的身体相关性。在AIM 1中，我们假设AMPAR之间的良好结构差异 组件对于产生特征性门控调制和提议以揭示建筑物至关重要。 在不同功能状态下最多包含多达两种类型的辅助亚基的异端AMPAR的调节 在确定使用Cryo-EM时。通过比较结构，可以解释如何辅助的新机械模型 ilariare子单位控制时间过程和门控的幅度可能会出现，这将得到验证 电生理学。接下来，当前可用的冷冻EM结构揭示了周围存在脂质 综合体。我们假设这些脂质在AMPAR门控调制中起重要功能，这将 在AIM2中进行测试。最后，我们建议AMPAR/辅助亚基复合物在生理附近制备 确定的条件必须研究，以构建其变构门的更精确的机械模型 调制。在AIM 3中，我们建议解决AMPAR/辅助亚基的高分辨率冷冻EM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 在确定和电生理数据中获得的调查。辅助亚基在调整离子通道GAT-的作用 预计ING动力学对电路动力学有重大影响。总之，这项研究的结果 期望提高我们对AMPAR功能的机械理解，并有助于开发新的Thera- 可以减轻神经和精神疾病中AMPAR失调的精细化合物， 例如阿尔茨海默氏病，中风，自闭症，拉斯穆森和边缘脑炎和癫痫发作。