蛋白质乙酰化修饰在创伤性脑损伤（TBI）神经修复中可能具有重要作用。课题组前期发现，SIRT2基因敲除明显增加TBI后损伤半暗区神经元凋亡，降低与神经元存活相关的磷酸化ERK1/2水平，加重神经功能障碍。但是SIRT2介导的神经保护作用机制尚未阐明。我们推测，SIRT2通过去乙酰化修饰MEK激活ERK信号通路从而保护TBI后神经损伤。为验证此假说，本项目首先过表达野生型或模拟乙酰化突变MEK蛋白后检测其乙酰化水平和催化活性；然后构建siRNA文库筛选MEK的乙酰化酶，免疫共沉淀检测SIRT2与MEK的相互关系。进一步通过神经元牵张损伤模型和小鼠控制性皮层损伤模型，分别从细胞和器官水平观察SIRT2基因敲除后MEK/ERK信号通路的乙酰化和磷酸化及下游基因表达变化，并评估TBI后神经损伤和神经功能改变。期望揭示SIRT2介导的MEK乙酰化修饰调控机制，为TBI神经保护提供新的治疗靶点和策略。

Lysine acetylation，an important post-translational modification (PTM) to modulate protein structure and function, plays a crucial role in the neural repair after traumatic brain injury (TBI). We previously found that SIRT2 knock out (KO) increased TBI-induced neuron apoptosis and decreased phosphorylation of ERK1/2, resulting in a significant deterioration in neurologic deficits, compared with the wild type (WT) group. The mechanism of SIRT2 mediated neuroprotection, however, remains elusive. We postulated that SIRT2 activates mitogen-activated protein kinase kinase (MEK) by deacetylation prevents TBI induced neural injury. To verify this hypothesis, we test the level of MEK acetylation and assay its activity after treatment with deacetylase inhibitor. To further determine which lysine residuse plays a major role in the regulation of MEK, we mutate each of putative acetylation sites, acquired from sequence alignments from diverse species, to arginine (R) or glutamine (Q) and assay their activity individually. A siRNA library is also generated to search for potential lysine acetyltransgerase (KATs) for MEK. Co-immunoprecipitations is undertaken to elucidate whether endogenous MEK interacted with SIRT2. The project will not only observe TBI induced acetylation and phosphorylation of MEK/ERK in SIRT2 KO mouse and primary neuron, using stretch induced cell injury or controlled cortical injury model, but also evaluate the effects of SIRT2 KO on neuronal cell injury and behavioral changes following TBI. Our study aim to uncover a previously unknown mechanism by which SIRT2 mediated deacetylation and activation of MEK stimulate ERK signal pathway to protect neuronal cells, and provide new treatment strategies for neurological function restoration after TBI.