Molecular organization of CNS synapses

描述（由申请人提供）：突触可塑性对大脑功能和发育至关重要。本提案的总体目标是了解NMDA受体（NMDARs）激活可导致海马突触强度（LTP和LTD）双向改变的分子机制。我们的初步研究表明，含有NR 2A和NR 2B的NMDAR分别选择性地与海马CA 1突触的LTP或LTD偶联。我们的总体假设，初步实验的支持，是NR 2A和NR 2B亚基的差异与突触后信号分子介导的可塑性变化。这些发现为理解NMDAR信号传导提供了令人兴奋的新进展，这是神经科学的核心问题，与大脑成熟，学习和记忆以及许多神经和神经精神疾病有关。该基金的具体目标将扩展这些观察，并以系统的方式研究NMDAR信号的潜在机制。目的1将使用药理学和分子遗传学方法的组合来表征NR 2A-与NR 2B-NMDARs在Ras-MAP激酶信号传导、AMPAR运输和海马突触可塑性中的不同作用。目标2将测试的想法，PSD-95家族的支架蛋白（结合到NR 2A/2B）的不同成员在AMPAR运输，突触传递和LTP/LTD中具有不同的功能。目标3将使用免疫沉淀的NMDAR复合物从大脑中识别和随后表征的特定信号蛋白，优先与NR 2A-相对于NR 2B-NMDAR。最后，目标4将确定和表征的小GTTRAP，这是新兴的突触抑制和可能的突触消除的重要球员的效应蛋白。总之，这些目标将使我们能够获得新的和基本的洞察NMDAR的分子组织和他们的突触后信号通路在中央兴奋性神经元。

DESCRIPTION (provided by applicant): Synaptic plasticity is essential for brain function and development. The overall objective of this proposal is to understand the molecular mechanisms by which activation of NMDA receptors (NMDARs) can lead to bidirectional modification of synaptic strength (LTP and LTD) in the hippocampus. Our Preliminary Studies suggest that NR2A- and NR2B-containing NMDARs are selectively coupled to LTP or LTD of hippocampal CA1 synapses, respectively. Our overall hypothesis, supported by preliminary experiments, is that NR2A and NR2B subunits are differentially associated with postsynaptic signaling molecules that mediate plasticity changes. These findings offer exciting new inroads into understanding NMDAR signaling, which is a central question in neuroscience and relevant to brain maturation, learning and memory, and many neurological and neuropsychiatric diseases. The Specific Aims of this grant will extend these observations and investigate the underlying mechanisms of NMDAR signaling in systematic fashion. Aim 1 will characterize the differential roles of NR2A- versus NR2B-NMDARs in Ras-MAP kinase signaling, AMPAR trafficking and hippocampal synaptic plasticity, using a combination of pharmacological and molecular genetic approaches. Aim 2 will test the idea that different members of the PSD-95 family of scaffold proteins (which bind to NR2A/2B) have different functions in AMPAR trafficking, synaptic transmission and LTP/LTD. Aim 3 will use immunoprecipitation of NMDAR complexes from brain to identify and subsequently characterize the specific signaling proteins that are preferentially associated with NR2A- versus NR2B-NMDARs. Finally, Aim 4 will identify and characterize the effector proteins of the small GTPase Rap, which is emerging as an important player in synaptic depression and possibly synapse elimination. Together these aims will allow us to gain novel and fundamental insight into the molecular organization of NMDARs and their postsynaptic signaling pathways in central excitatory neurons.