脑缺血协同诱导Drp1磷酸化和乙酰化的分子机制及其在线粒体损伤中的作用

Dynamin相关蛋白-1（Drp1）在线粒体损伤和神经元凋亡中发挥关键作用。已知脑缺血诱导的Drp1磷酸化促进线粒体分裂，最近发现，Drp1过度乙酰化也是脑缺血导致线粒体分裂的重要原因，但目前尚不清楚①Drp1如何被乙酰化，②Drp1磷酸化与乙酰化之间的内在联系，③调节Drp1乙酰化的上游信号。我们前期研究发现，脑缺血促进GCN5L1与Drp1结合及其在线粒体中的共定位，神经元细胞中敲除GCN5L1抑制OGD诱导的线粒体分裂，提示GCN5L1介导的Drp1乙酰化是线粒体分裂所必需的。据此提出“脑缺血通过诱导GCN5L1与Drp1结合而使Drp1乙酰化，其乙酰化依赖于Drp1磷酸化，Drp1被双重修饰激活是导致线粒体分裂的重要原因”的假说。本项目对上述3个未知问题进行探究，验证所提假说，通过比较阻断不同信号和抑制Drp1对线粒体损伤的保护效果，寻求防治缺血性脑损伤的有效途径。

Dynamin-related protein 1 (Drp1) plays a key role in ischemic mitochondrial damage and neuronal death. It is well known that cerebral ischemia-induced Drp1 phosphorylation promotes mitochondrial fission. Recently, it is found that hyperacetylation of Drp1 also is an important reason why cerebral ischemia causes mitochondrial fission. However, several fundamental questions remained: (1) how does Drp1 be acetylated? (2) what is the relationship between Drp1 phosphorylation and Drp1 acetylation? and (3) what is the upstream signaling whereby Drp1 acetylation is regulated? Our preliminary findings show that cerebral ischemia induces the association of GCN5L1 with Drp1 and enhances their co-localization in the mitochondria, and that CRISPR/Cas9-mediated knockout of GCN5L1 in the neuronal cells inhibits OGD-induced mitochondrial fission, indicating that GCN5L1-mediated Drp1 acetylation is required for mitochondrial fission. On the basis of these observations, we hypothesized that cerebral ischemia promotes Drp1 acetylation through facilitating GCN5L1 interaction with Drp1 in a Drp1 phosphorylation-dependent manner, and Drp1 activation by both acetylation at lysine 642 and phosphorylation at serine 616 is an important cause of mitochondrial fission. In this study, we shall investigate the above-mentioned 3 unresolved issues and test and verify our hypothesis. This study will provide a novel therapeutic strategy for treatment of post-ischemic neuronal death.