人参皂苷Rg1通过CDK5途径减轻Aβ_(25-35)诱导的神经元tau蛋白磷酸化

Ginsenoside Rg1 Atteouates Tau Hyperphosporylation Induced by Fibrillar Aβ_(25-35) in Primary Cortical Neurons through Cyclin-Dependent Kinase 5 Signaling

目的探讨在Aβ25-35诱导的皮层神经元tau蛋白过度磷酸化中,人参皂苷Rg1对tau蛋白过度磷酸化及周期依赖性蛋白激酶5(CDK5)的激动亚基p35的影响。方法通过蛋白免疫印迹法检测胎鼠皮层神经元CDK5的两个亚基cdk5和p35/p25的蛋白水平,以及CDK5的磷酸化底物tau蛋白在Thr205和Ser404位点的磷酸化水平。结果凝聚态Aβ25-35(20μmol/L)作用于皮层神经元12h,皮层神经元中p35裂解成p25的数量增多,tau蛋白在Thr205和Ser404位点的磷酸化水平增高,对cdk5亚基表达水平的影响不明显。人参皂苷Rg1和calpain特异性抑制剂calpeptin可稳定皮层神经元的p35蛋白,减少p25生成,人参皂苷Rg1和CDK5特异性抑制剂roscovitine可减轻凝聚态Aβ25-35诱导的皮层神经元tau蛋白过度磷酸化。结论CDK5可能参与人参皂苷Rg1减轻寡聚态Aβ25-35诱导的皮层神经元tau蛋白过度磷酸化。

Objective To explore the effect of ginsenoside Rgl on cyclin-dependent kinase 5 activator p35 in the process of β-amyloid peptide 25-35-induced tau hyperphosporylation. Methods The lev- els of cyclin-dependent kinase 5 activator-p35/p25, cdk5 and tau phosphorylation in the site of Thr205, Ser404 were detected by Western blot. Results After exposure to Aβ25-35（20 gmol/L） for 12 h, the levels of p25 and p25/p35 were increased, but the expression of cdk5 has not markedly changed. Meanwhile, the levels of tau protein phosphorylation in the sites of Thr205 and Ser404 were also enhanced. After pretreatment with ginsenoside Rg1 or calpeptin, a specific inhibitor of calpain, the levels of p25 and p25/p35 were decreased. After pretreatment with ginsenoside Rgl or roscovitine, a specific inhibitor of CDK5, tau hyperphosphorylation induced by Aβ25-35reduced. Conclusion Cyclindependent kinase 5 may be involved in ginsenoside Rgl attenuating fibrillar Aβ25-35-induced tau hyperphosporylation in cortical neurons.