Synaptic Plasticity after Brain Ischemia

本项目的目的是研究谷氨酸受体复合体在经过短暂的 缺血再灌注期(I/R)。具体地说，我们将研究蛋白质组成， NMDA和AMPA受体复合体的运输、聚集和信号转导 缺血症。NMDA和AMPA受体与PSD-95等多种蛋白质形成簇或复合体 和突触后密度(PSD)中的SynGAP。这些受体簇的成分是动态的 在长期增强过程中受到调节。然而，I/R后这些受体的过度激活会导致 兴奋性毒性。对导致兴奋性毒性的谷氨酸受体复合体结构异常的认识 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 研究突触形态和分子修饰的最先进技术，并发现戏剧性的 I/R后突触超微结构、分子组成和信号转导的变化。 我们的研究清楚地表明，信号蛋白激酶的招募和积累 PSD中的酪氨酸磷酸化蛋白是PSD中最主要的两个分子事件 因为I/R的影响在谷氨酸能通路上最为明显，所以我们将 进一步研究NMDA和AMPA受体复合体这两个关键的突触调节因子在 体内I/R和神经细胞培养的氧糖剥夺(OGD)。 目的1将验证脑缺血导致NMDA异常重组和 通过关键突触蛋白的酪氨酸磷酸化形成AMPA受体复合体，这对 导致脑缺血后的兴奋性中毒。目的2将研究NR2B、PSD95的酪氨酸磷酸化 OGD发作后的SynGAP改变了它们的突触运输和聚集，导致了修改 神经细胞培养中突触形态和信号转导的研究。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， 从而可能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.