Molecular Determinants of NMDA-R Trafficking

描述（由申请人提供）：必须仔细控制存在于特定突触处的NMDA型谷氨酸受体（NMDA-R）的数量、性质和亚基组成，以调节钙内流和与受体及其活化相关的不同信号级联。许多脑区域中的突触经历NMDA-R的亚基组成从主要含有NR 2B到主要含有NR 2A的转换。这种开关需要突触活动或感觉经验，改变受体功能，并被认为影响突触可塑性。最近的研究表明，NR 2亚基以亚基特异性的规则控制NMDA-R向突触的运输。NR 2B是纳入一个组成性或活动独立的方式，而NR 2A的掺入需要突触活动，并保留在细胞内的情况下it. We建议调查的分子决定因素，控制差分贩运的NMDA-Rs，参与开关的NR 2亚基的机制，和改变突触NMDA-Rs的组成的后果。主要假设是NR 2亚基控制突触插入和NMDA-Rs的稳定以及突触发生和棘形态。这些研究将使用大鼠大脑的器官型海马切片和几种补充方法，包括分子生物学，生物化学，荧光成像和电生理学。一种创新的功能测定将用于检测NMDA-R掺入突触。NR 2亚基的嵌合体将用于检查不同结构基序所起的作用。具体目标是：1）检验NR 2亚单位携带控制突触掺入和NMDA-R稳定的信号的假设; 2）检验NR 2A突触掺入需要活性依赖性去除含NR 2B的受体并且不依赖于钙内流的假设; 3）检验NR 2亚单位控制突触发生速率并且塑造树突棘的动力学和形态的假设。 公共卫生相关性：NMDA型谷氨酸受体是突触的重要组成部分，参与突触可塑性、脑发育和病理学过程。必须很好地控制存在于特定突触处的NMDA-R的数量、性质和亚基组成，以调节与受体及其活化相关的过程。我们的目标是阐明控制突触上NMDA-R的数量和亚基组成的分子机制。这一领域的研究是准备为理解和治疗与认知缺陷相关的多种神经精神综合征具有重要意义。

DESCRIPTION (provided by applicant): The number, properties, and subunit composition of NMDA-type glutamate receptors (NMDA-Rs) present at a particular synapse must be under careful control in order to regulate calcium influx and different signaling cascades associated with the receptor and its activation. Synapses in many brain regions undergo a switch in the subunit composition of NMDA-Rs from predominantly containing NR2B to predominantly containing NR2A. This switch requires synaptic activity or sensory experience, alters receptor function, and it is thought to affect synaptic plasticity. Recent studies showed that NR2 subunits control the trafficking of NMDA-Rs into synapses with subunit-specific rules. NR2B is incorporated in a constitutive or activity- independent manner, whereas NR2A incorporation requires synaptic activity and is retained intracellularly in the absence of it. We propose to investigate the molecular determinants that control the differential trafficking of NMDA-Rs, the mechanisms involved in the switch of NR2 subunits, and the consequences of altering the composition of synaptic NMDA-Rs. The principal hypothesis is that NR2 subunits control synaptic insertion and stabilization of NMDA-Rs as well as synaptogenesis and spine morphology. These studies will use organotypic hippocampal slices from rat brain and several complementing methodologies, including molecular biology, biochemistry, fluorescence imaging, and electrophysiology. An innovative functional assay will be used to detect incorporation of NMDA-Rs into synapses. Chimeras of NR2 subunits will be used to examine the role played by different structural motifs. The specific aims are: 1) To test the hypothesis that NR2 subunits carry a signal that controls synaptic incorporation and stabilization of NMDA- Rs; 2) To test the hypothesis that NR2A synaptic incorporation requires activity-dependent removal of NR2B-containing receptors and is independent of calcium influx; 3) To test the hypothesis that NR2 subunits control the rate of synaptogenesis and shape the dynamics and morphology of dendritic spines. PUBLIC HEALTH RELEVANCE: Relevance NMDA-type glutamate receptors are a key component of synapses and they are involved in synaptic plasticity, brain development and pathology. The number, properties and subunit composition of the NMDA-Rs present at a particular synapse must be well controlled to regulate processes associated with the receptor and its activation. Our goal is to elucidate the molecular mechanisms that control the number and subunit composition of NMDA-Rs present at synapses. This field of research is poised to be of great significance for the understanding and treatment of multiple neuropsychiatric syndromes associated with cognitive deficits.