Src介导GluK2酪氨酸磷酸化调节钙离子信号的机制

Excitotoxicity is the major mechanism in ischemic brain damage. Overactivation of kainate receptors, which is one of the ionic glutamate receptors, is closely related to excitotoxic neuron lesions. Our previous reports showed that Src promoted GluK2 tyrosine phosphorylation and upregulated the GluK2-containing kainate receptor responses and downstream JNK3 signal pathway after ischemia/reperfusion. .To elucidate the mechanisms underlying the regulation of GluK2 function by Src-mediated tyrosine phosphorylation, the current project is designed to study the mechanisms underlying the intracellular calcium increase，the regulation of endocytosis by calcium, and the downstream calcium signal pathway in cell apoptosis using calcium image, confocal microscopy, live cell fluorescence imaging, etc. All the data from this study will provide theoretical and experimental evidence for the development of drugs for clinical therapy of ischemia.

兴奋毒性是缺血性脑损伤的主要机制。海人藻酸受体（Kainate Receptor, KAR）的过度激活与兴奋毒性神经元损伤存在密切联系。申请者本人的前期研究结果表明：在缺血性脑损伤中，Src促进KA受体GluK2亚基的酪氨酸磷酸化，上调KA受体GluK2亚基的功能及脑缺血诱导的神经元凋亡信号通路。.为了进一步阐明Src介导的酪氨酸磷酸化修饰方式对GluK2受体功能调节的具体机制，本项目拟采用钙成像分析、激光共聚焦、活细胞荧光成像等方法研究Src介导GluK2酪氨酸磷酸化引起细胞内钙离子浓度升高，钙离子对受体内吞以及胞内不同钙离子信号通路的调节机制。通过以上研究，为筛选脑缺血潜在的药物治疗靶点提供理论基础。

本项目主要围绕胞内钙离子在GluK2受体介导的兴奋毒中的作用展开研究。研究表明：Src主要通过SH2结构域与GluK2受体的胞内区域结合，促进GluK2酪氨酸磷酸化，从而改变受体钙离子通透性。GluK2受体介导的钙离子内流诱导胞内钙库释放共同组成胞内钙离子升高的机制。胞内钙离子进一步激活钙调磷酸(Cancineurin,CaN )，调节Dynamin去磷酸化和PICK1参与的GluK2受体内吞，促进KA刺激诱导的兴奋毒；另外，钙离子激活胞内凋亡信号JNK3-c-Jun和FasL表达，促进兴奋毒引起的细胞损伤。以上结果进一步揭示了GluK2受体在缺血性脑中风促进神经元损伤的详细机制，为研究缺血性脑中风的分子机制提供更多的理论基础。