中文摘要：

阿尔茨海默病（Alzheimer＇s disease,AD）的病理特征之一是神经元内存在神经原纤维缠结（neurofibrillary tangles,NFTs）,后者是由过度磷酸化的微管相关蛋白tau形成的双股螺旋细丝（pairedhelical filaments,PHFs）构成。为了探讨丝裂原活化蛋白激酶（mitogen-activated protein kinase,MAPK）在微管相关蛋白tau磷酸化中的作用及机制,本实验用0.1μg/mL、0.2μg/mL和0.4μg/mL三种不同浓度的MAPK激动剂anisomycin处理小鼠成神经瘤细胞株（mouse neuroblastoma cells,N2a）,检测MAPK活性的变化及其与tau蛋白多个AD相关位点过度磷酸化的关系,并检测糖原合酶激酶-3（glycogen synthase kinase-3,GSK-3）和蛋白激酶A（protein kinase A,PKA）的活性变化。结果显示,anisomycin以剂量依赖的方式激活MAPK活性,但免疫印迹结果显示tau蛋白的Ser-198/199/202位点和Ser-396/404位点的过度磷酸化只在anisomycin浓度为0.4μg/mL时出现,三种浓度的anisomycin均未引起tau蛋白Ser-214位点磷酸化的改变;同时,GSK-3活性在anisomycin为0.1μg/mL时没有明显变化,当anisomycin浓度升高到0.2μg/mL和0.4μg/mL时出现明显增高,而PKA的活性没有明显的改变。使用GSK-3的特异性抑制剂氯化锂（LiCl）则完全阻断MAPK被过度激活导致的tau蛋白磷酸化水平的增高,而同时MAPK活性不受影响。以上结果提示：过度激活MAPK可以导致tau蛋白Ser-198/199/202和Ser-396/404位点过度磷酸化,其机制可能涉及MAPK激活GSK-3的间接作用。

英文摘要：

One of the pathological feathers of Alzheimer’s disease （AD） is neurofibrillary tangles （NFTs）, which consist of paired helical filaments （PHFs） formed by hyperphosphorylated microtubule-associated protein tau. To study the role of mitogen-activated protein kinase （MAPK） in tau hyperphosphorylation and the underlying mechanism, wild type mouse neuroblastoma cells （N2a） were dealt with different concentrations （0.1 μg/mL, 0.2 μg/mL and 0.4 μg/mL） of anisomycin （an activator of MAPK） for 6 h. The relationship between MAPK activity and tau phosphorylation at some Alzheimer-sites was analyzed, and the activities of protein kinase A （PKA） and glycogen synthase kinase-3 （GSK-3） were detected. The results showed that anisomycin activated MAPK in a dose-dependent manner, but tau hyperphosphorylation at Ser-198/199/202 and Ser-396/404 sites was only observed when the concentration of anisomycin was at the level of 0.4 μg/mL, and the alteration of tau phosphorylation at Ser-214 showed no significant difference in different groups. 0.2 μg/mL and 0.4 μg/mL of anisomycin led to an increase in the activity of GSK-3, respectively, but had no effect on the activity of PKA. Lithium chloride, a specific inhibitor of GSK-3, completely abolished the anisomycin-induced elevation of tau phosphorylation without any effect on the activity of MAPK. In conclusion, overactivation of MAPK up to a certain degree induces tau hyperphosphorylation at Ser-198/199/202 and Ser-396/404 sites, and this is probably related to the effect of activated GSK-3 by MAPK.