褪黑素对花萼海绵诱癌素诱导的tau蛋白过度磷酸化的影响

目的探讨褪黑素(Mel)对花萼海绵诱癌素(CA)在成神经瘤细胞诱导的tau蛋白过度磷酸化的影响及其机制。方法采用鼠野生型成神经瘤细胞(N2awt),给予CA处理,或同时给予50μmol/L Mel处理,用免疫荧光检测tau蛋白磷酸化水平,32P-特异底物标记技术检测GSK-3活性,免疫印迹技术检测P-Ser9-GSK-3β和GSK-3β的表达水平,计算P-Ser9-GSK-3β/GSK-3β的比率。结果①CA可在N2awt细胞使tau蛋白在Ser396/404位点和Ser198/202位点过度磷酸化,同时伴有GSK-3活性升高和P-Ser9-GSK-3β表达水平降低。②Mel对CA引起的tau蛋白过度磷酸化有保护作用;Mel同时对抗CA诱导的GSK-3活性升高和P-Ser9-GSK-3β表达水平降低。结论Mel可减轻CA引起的tau蛋白过度磷酸化,其机制可能与调节细胞内P-Ser9-GSK-3β的表达水平和改变GSK-3活性有关。

Effect of melatonin on calyculin A-induced tau hyperphosphorylation

Objective To investigate the in vivo effect of melatonin(Mel) on calyculin A(CA)-induced tau hyperphosphorylation in neuroblastoma cells(N2awt).Methods We treated N2awt cells with CA or CA and 50 μmol/L Mel,detected the level of tau phosphorylation with immunofluorescence,and assayed the activities of GSK3 and the ratio of GSK-3β phosphorylated at Ser9 site to total GSK-3β.Results CA treatment led to tau hyperphosphorylation accompanied with the increased activity of GSK-3 and the decreased ratio of GSK-3β phosphorylated at Ser9 site to total GSK-3β.When the cells were incubated simultaneously with CA and 50 μmol/L Mel,the CA-induced tau hyperphosphorylation,GSK-3 activation and the ratio of GSK-3β phosphorylated at Ser9 site to total GSK-3β decrease were attenuated.Conclusion Melatonin protects neuroblastoma cells from CA-induced tau hyperphosphorylation.Its protection may be related to the regulation of GSK-3 activity and the ratio of GSK-3β phosphorylated at Ser9 site to total GSK-3β increase.