Supramolecular Organization of the Postsynaptic Density

描述（由申请人提供）：突触是神经元通信的基础。最清楚地表明，在啮齿动物海马CA 1区，突触的效力可以随时间而变化。这种突触调制是高级大脑功能的许多方面的基础。它的功能障碍与发育障碍和某些类型的癫痫有关，并且可能对各种神经精神疾病很重要。现在普遍认为，位于突触后密度（PSD）内的蛋白质在调节突触效能中起着关键作用，但这些蛋白质在PSD内的组织仍然很大程度上未知。阐明PSD的超分子结构是本项目的长期目标。目前的证据表明，每个NMDA受体与许多信号，适配器和细胞骨架蛋白结合，形成单独的半自主信号“模块”，但这些现在只被理解为生化抽象。该研究将免疫金EM与高分辨率电子断层扫描相结合，将NMDAR模块作为一个有组织的物理结构进行研究，确定其大小和形状，并检查其内部组织。它还探讨了组织这些模块到更大的领域内的PSD，并调查PSD的细胞骨架的关系。特异性目标1确定NMDAR信号模块的形态;特异性目标2阐明NMDAR模块的内部组织，使用免疫金定位来表征模块内四种主要蛋白质的层状组织;特异性目标3检查NMDAR模块沿突触并置沿着的分布;和具体目标4研究PSD和肌动蛋白细胞骨架之间的联系，以及脊柱内肌动蛋白丝的组织。这项研究计划解决了海马突触分子信号通路的物理组织，重点是与一种特别重要的神经递质受体NMDA受体相关的蛋白质。这项工作的成功完成将提高我们对大脑突触机制的理解，将为学习和记忆的基本过程提供新的线索，并可能有助于理解各种神经，发育和精神疾病的原因。

DESCRIPTION (provided by applicant): Synapses are fundamental to neuronal communication. As most clearly demonstrated in the CA1 field of rodent hippocampus, synaptic efficacy can vary over time. This synaptic modulation underlies many aspects of higher brain function. Its dysfunction is implicated in developmental disorders and certain types of epilepsy, and may be important for a variety of neuropsychiatric diseases. It is now generally agreed that proteins lying within the postsynaptic density (PSD) play a key role in regulating synaptic efficacy, but the organization of these proteins within the PSD remains largely unknown. Elucidating the supramolecular architecture of the PSD is the long-term goal of this project. Current evidence suggests that each NMDA receptor combines with numerous signaling, adaptor, and cytoskeletal proteins to form individual semi-autonomous signaling "modules," but these are now understood only as biochemical abstractions. The proposed research combines immunogold EM with high-resolution electron tomography to study the NMDAR module as an organized physical structure, determining its size and shape, and examining its internal organization. It also explores the organization of these modules into larger domains within the PSD, and investigates the relationship of the PSD to the cytoskeleton. Specific Aim 1 determines the morphology of NMDAR signaling modules; Specific Aim 2 elucidates the internal organization of NMDAR modules, using immunogold mapping to characterize the laminar organization of four major proteins within a module; Specific Aim 3 examines the distribution of NMDAR modules along the synaptic apposition; and Specific Aim 4 investigates contacts between the PSD and the actin cytoskeleton, and the organization of actin filaments within the spine. This research proposal addresses the physical organization of molecular signaling pathways at synapses in the hippocampus, focusing on proteins associated with an especially important type of neurotransmitter receptor, the NMDA receptor. Successful completion of this work will improve our understanding of synaptic mechanisms in the brain, will provide new clues regarding fundamental processes that underlie learning and memory, and may help understand the causes of a variety of neurological, developmental, and psychiatric disorders.