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。这项建议的总体目标是了解激活NMDAR(NMDAR)导致海马区突触强度(LTP和LTD)双向改变的分子机制。我们的初步研究表明，含有NR2A和NR2B的NMDAR分别选择性地与海马CA1突触的LTP或LTD偶联。我们的总体假设得到了初步实验的支持，即NR2A和NR2B亚单位与介导可塑性变化的突触后信号分子存在差异。这些发现为理解NMDAR信号提供了令人兴奋的新途径，NMDAR信号是神经科学中的一个中心问题，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。这项拨款的具体目标将扩大这些观察结果，并以系统的方式研究NMDAR信号的潜在机制。目的1利用药理学和分子遗传学相结合的方法，研究NR2A型和NR2B型NMDARs在RAS-MAP信号转导、AMPAR转运和海马突触可塑性中的不同作用。目的2将验证PSD-95家族的不同成员(与NR2A/2B结合)在AMPAR运输、突触传递和LTP/LTD中具有不同功能的想法。AIM 3将使用脑中NMDAR复合体的免疫沉淀来识别并随后表征优先与NR2A-与NR2B-NMDAR相关的特定信号蛋白。最后，目标4将识别和表征小GTP酶Rap的效应蛋白，它正在成为突触抑制和可能的突触消除的重要参与者。总之，这些目标将使我们能够对NMDAR的分子组织及其在中枢兴奋性神经元中的突触后信号通路获得新的和基本的见解。

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.