Molecular organization of CNS synapses

描述（申请人提供）：突触可塑性对大脑功能和发育至关重要。本研究的总体目标是了解NMDA受体（NMDARs）激活导致海马突触强度（LTP和LTD）双向修饰的分子机制。我们的初步研究表明，含有NR2A-和nr2b的NMDARs分别选择性地偶联到海马CA1突触的LTP或LTD。我们的总体假设得到了初步实验的支持，即NR2A和NR2B亚基与介导可塑性变化的突触后信号分子有不同的关联。这些发现为理解NMDAR信号提供了令人兴奋的新进展，这是神经科学的一个核心问题，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。该资助的具体目标将扩展这些观察结果，并以系统的方式研究NMDAR信号传导的潜在机制。目的1将利用药理学和分子遗传学方法的结合，表征NR2A-与NR2B-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。Aim 2将测试PSD-95支架蛋白家族（与NR2A/2B结合）的不同成员在AMPAR运输、突触传递和LTP/LTD中具有不同功能的观点。目的3将使用来自大脑的NMDAR复合物的免疫沉淀来鉴定并随后表征优先与NR2A-与NR2B-NMDARs相关的特定信号蛋白。最后，Aim 4将鉴定和表征小GTPase Rap的效应蛋白，该蛋白在突触抑制和突触消除中发挥重要作用。这些目标将使我们对中枢兴奋性神经元中NMDARs的分子组织及其突触后信号通路有新的和基本的了解。

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.