Illuminating the structure and function of CACNG5 and 7

阐明 CACNG5 和 7 的结构和功能

• 批准号: 10452080
• 负责人: Terunaga Nakagawa
• 金额: $ 15.85万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-15 至 2024-05-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10452080
• 关键词: AMPA Receptors; Affect; Attenuated; Binding; Binding Proteins; Biological Models; Biology; Brain; Brain Neoplasms; Calcium; Calcium ion; Cell membrane; Cell physiology; Cells; Cerebellum; Cognition; Complex; Cryoelectron Microscopy; Cytoplasmic Granules; Development; Disease; Distant; Drug Targeting; Electrophysiology (science); Family; Functional disorder; Future; G-substrate; Genes; Glaucoma; Glioblastoma; Glutamate Receptor; Glutamates; Goals; Golgi Apparatus; Hippocampus (Brain); Homo; Impaired cognition; Intellectual functioning disability; Ion Channel; Ion Channel Gating; Ischemic Brain Injury; Kinetics; Learning; Ligands; Long-Term Depression; Mediating; Membrane; Membrane Proteins; Memory; Mental disorders; Molecular; Motor; Movement Disorders; Neuroglia; Neurons; Neurotransmitters; Nomenclature; Outcome; Outcomes Research; Pain; Pathologic; Permeability; Pharmacology; Physiological; Polyamines; Probability; Protein Family; Proteins; Reagent; Regulation; Relapse; Research; Resolution; Resources; Role; Second Messenger Systems; Seizures; Sequence Homology; Signal Transduction; Specificity; Structure; Synapses; Synaptic Transmission; Synaptic plasticity; addiction; base; cell type; conditioned fear; drug development; genetic regulatory protein; improved; insight; molecular modeling; nervous system disorder; neuronal survival; novel therapeutics; positive allosteric modulator; protein function; rational design; reduce symptoms; side effect; trafficking; tumor addiction

Project Summary The majority of excitatory synaptic transmission in the CNS synapses are mediated by the AMPA-type ionotropic glutamate receptor (AMPAR), a ligand gated ion channel activated by the neurotransmitter glutamate. The pore forming subunits of AMPARs (GluA1-4 subunits) assemble as homo- or hetero-tetramers. The native AMPARs co-assemble with a rich repertoire of transmembrane auxiliary subunits which belong to different protein families, such as TARP, GSG1L, CNIH, CKAMP, and synDIG. Incorporation of different auxiliary subunit confers AMPAR with unique ion channel gating kinetics, pharmacology, and in many cases trafficking regulation. The varying expression patters of auxiliary subunits in brain provides opportunities to produce drugs that target specific AMPAR auxiliary subunit combinations, which would have improved target specificity and less side effects over existing ones such as Perampanel (NAM) and ampakines (PAM) that bind to the common pore forming subunits of AMPARs (GluA1-4). Indeed, several NAMs that are selective to TARP gamma-8 containing AMPARs are already available and effective in seizures and pain. All the TARPs except for the TARP gamma-2 (encoded by CACNG2) are understudied and present in Phanos and IDG resource. Among these the biology is least understood for the type-II TARPs (CACNG5 and 7, which encodes TARP gamma-5 and 7), whose sequences are distant from the type-I TARPs (CACNG2, 3, 4, and 8, which encodes TARP gamma-2, 3, 4, and 8). Currently, it is established that type-II TARPs bind to calcium permeable AMPA-Rs (CP-AMPAR) that lacks the GluA2 subunit and regulate their functions. TARP gamma-5 is expressed in the CA2 of hippocampus and Bergmann glia of cerebellum, whereas TARP gamma-7 is enriched in cerebellar neurons (Purkinje, basket, stellate, granule, Bergmann glia, and Golgi cells). Consistently, CP-AMPARs were functionally detectable in these cell types. The function of CP-AMPARs is highly relevant to ischemic brain damages, brain tumors, addiction, fear-conditioning, and motor function. Compounds that selectively target type-II TARP containing CP-AMPARs are promising reagents for pharmacological manipulation to study the cellular function of these complexes and may facilitate the future development of drugs for treating the pathological conditions described above. We hypothesize that the type-II TARPs operate under different molecular mechanism from type-I TARPs, which do not specialize in CP-AMPAR modulation. To illuminate the structural basis for the mechanism of type-II TARP function, we propose to solve the high-resolution structures of a type-II TARP in complex with CP-AMPAR, which is currently missing. Based on the insights obtained from the structures of other AMPAR/auxiliary subunit complexes we predict that the differences in sidechain interaction network at the protein interaction interface determine the types of functional readout of modulation. The outcome of this research is expected to produce high resolution molecular model of the interaction interfaces between AMPAR and type-II TARP, which in turn would facilitate further functional research at the molecular level of currently understudied type-II TARPs (i.e. CACNG5 and 7).

项目摘要 中枢神经系统突触中的大部分兴奋性突触传递是由AMPA型亲离子作用介导的 谷氨酸受体(AMPAR)，一种由神经递质谷氨酸激活的配体门控离子通道。毛孔 形成AMPAR的亚基(GluA1-4亚基)以同源或异源四聚体的形式组装。原生AMPAR 与属于不同蛋白质家族的丰富的跨膜辅助亚基共同组装， 如TARP、GSG1L、CNIH、CKAMP和SynDIG。不同辅助亚单位的结合赋予AMPAR 具有独特的离子通道门控动力学、药理学和在许多情况下的转运调节。变化无常 大脑辅助亚单位的表达模式为生产针对特定亚基的药物提供了机会 Ampar辅助亚单位组合，这将提高靶标特异性并减少副作用 现有的与共同的孔道形成亚基结合的分子，如Perampanel(NAM)和Ampakines(PAM) AMPAR(GluA1-4)。事实上，对含有AMPAR的TARP Gamma-8具有选择性的几个NAM是 对癫痫发作和疼痛已经有效。除TARP Gamma-2(编码方式： CACNG2)，并存在于Phanos和IDG资源中。其中，生物学是最小的 对于II型tarp(CACNG5和7，编码TARP Gamma-5和7)，其序列 距离第一类tarp(CACNG2、3、4和8，编码TARP Gamma-2、3、4和8)很远。目前， 已经证实，II型Tarps与缺乏GluA2的钙通透性AMPA-Rs(CP-AMPAR)结合 亚单位和调节它们的功能。TARP-5在海马CA2区和Bergmann区均有表达 而TARP-7主要分布于小脑神经元(蒲肯野、篮状、星状、颗粒、 Bergmann胶质细胞和高尔基细胞)。在这些细胞类型中，CP-AMPAR在功能上是可检测到的。这个 CP-AMPAR的功能与缺血性脑损伤、脑肿瘤、成瘾、恐惧条件反射、 和运动功能。选择性靶向含有CP-AMPAR的II型TARP的化合物很有前景 用于药理操作的试剂，以研究这些复合体的细胞功能，并可能促进 治疗上述病理情况的药物的未来发展。我们假设 II型Tarp与I型tarp在不同的分子机制下工作，后者不专门 CP-AMPAR调制。为了阐明II型TARP功能的结构基础，我们 建议解决与CP-AMPAR形成的复合体中的II型TARP的高分辨率结构，目前 失踪。基于从其他AMPAR/辅助亚基复合体的结构中获得的见解，我们 预测蛋白质相互作用界面侧链相互作用网络的差异决定了 调制的功能读出类型。这项研究的结果有望产生高分辨率 AMPAR和II型TARP之间相互作用界面的分子模型，这反过来将有助于 在分子水平上进一步研究目前未被研究的II型Tarp(即CACNG5和7)的功能。