Synaptic Plasticity after Brain Ischemia

本项目的目的是研究谷氨酸受体复合物的调节后，简短的 缺血再灌注期（I/R）。具体来说，我们将研究蛋白质组成， NMDA和AMPA受体复合物的运输、聚集和信号转导 缺血NMDA和AMPA受体与许多蛋白质如PSD-95形成簇或复合物 和突触后致密物（PSD）中的SynGAP。这些受体簇的成分是动态的， 在长时程增强过程中受到调节。然而，I/R后这些受体的过度激活导致 兴奋性毒性导致兴奋性毒性的异常谷氨酸受体复合物组织的知识 可能为中风患者提供新的治疗途径。我们最近建立了一系列 国家的最先进的技术来研究突触形态和分子修饰，并发现戏剧性 I/R后突触超微结构、分子组成和信号转导的改变。具体地说， 我们的研究已经清楚地表明，信号蛋白激酶的募集和细胞的积累， PSD中的酪氨酸磷酸化蛋白，是PSD中改变的两个最主要的分子事件。 I/R后的突触由于I/R的影响在多巴胺能通路上最明显，我们将 进一步研究两个关键的突触调节因子，NMDA和AMPA受体复合物的调节， 体内I/R和神经元培养中的氧葡萄糖剥夺（OGD）。 目的1将检验脑缺血导致NMDA异常重组的假设， AMPA受体复合物通过关键突触蛋白的酪氨酸磷酸化， 缺血后兴奋性增强。目的2：研究NR 2B、PSD 95的酪氨酸磷酸化 和SynGAP在OGD发作后改变了它们的突触运输和聚集，导致修饰 突触形态学和神经元培养中的信号转导。这些研究将产生 了解异常谷氨酸受体组织介导的兴奋性毒性的全面数据， 从而可以为中风患者提供新的治疗途径。

The objective of this project is to study the regulation of glutamate receptor complexes after a brief period of ischemia followed by reperfusion (I/R). Specifically, we will investigate the protein composition, trafficking, clustering, and signal transduction of NMDA and AMPA receptor complexes associated with ischemia. NMDA and AMPA receptors form clusters or complexes with numerous proteins such as PSD-95 and SynGAP in postsynaptic densities (PSDs). Constituents of these receptor clusters are dynamically regulated during long-term potentiation. However, overactivation of these receptors after I/R leads to excitotoxicity. Knowledge of aberrant glutamate receptor complex organization that leads to excitotoxicity may provide new therapeutic avenues for stroke patients. We have recently established a series of state-of-the-art techniques to study synaptic morphological and molecular modifications, and found dramatic alterations in synaptic ultrastructure, molecular composition, and signal transduction after I/R. Specifically, our studies have clearly demonstrated that recruitment of signaling protein kinases, and accumulation of tyrosine phosphorylated proteins in PSDs, are two of the most dominant molecular events altered in synapses after I/R. Because the effects of I/R are most pronounced on glutamatergic pathways, we will study further the regulation of two key synaptic regulators, the NMDA and AMPA receptor complexes, after I/R in vivo and oxygen glucose deprivation (OGD) in neuronal culture. Aim 1 will test the hypothesis that brain ischemia leads to aberrant reorganization of NMDA and AMPA receptor complexes by means of tyrosine phosphorylation of key synaptic proteins, which contributes to excitotocixity after ischemia. Aim 2 will investigate whether tyrosine phosphorylation of NR2B, PSD95 and SynGAP after an episode of OGD alters their synaptic trafficking and clustering, leading to modification of synaptic morphology and signal transduction in neuronal cultures. These studies will produce comprehensive data for understanding aberrant glutamate receptor organization-mediated excitotoxicity, and thus may provide new therapeutic avenues for stroke patients.