Prolonged Alzheimer-like Tau Hyperphosphorylation Induced by Simultaneous Inhibition of Phosphoinositol-3 Kinase and Protein Kinase C in N2a cells

【摘要】 <正> Co-injection of wortmannin（inhibitor of phosphatidylinositol-3 kinase,PI3K）and GF109203X（inhibitor of protein kinase C,PKC）into the rat brain was found to induce spatial memory deficiency andenhance tau hyperphosphorylation in the hippocampus of rat brain.To establish a cell model with durativeAlzheimer-like tau hyperphosphorylation in this study,we treated N2a neuroblastoma cells with wortmanninand GF109203X separately and simultaneously,and measured the glycogen synthase kinase 3（GSK-3）activity by γ-（32）^P-labeling and the level of tau phosphorylation by Western blotting.It was found that theapplication of wortmannin alone only transitorily increased the activity of GSK-3（about 1 h）and the level oftau hyperphosphorylation at Ser³⁹⁶/Ser⁴⁰⁴ and Ser¹⁹⁹/Ser²⁰² sites（no longer than 3 h）;however,a prolongedand intense activation of GSK-3（over 12 h）and enhanced tan hyperphosphorylation（about 24 h）wereobserved when these two selective kinase inhibitors were applied together.We conclude that the simultaneousinhibition of PI3K and PKC can induce GSK-3 overactivation,and further strengthen and prolong the Alzheimer-like tau hyperphosphorylation in N2a cells,suggesting the establishment of a cell model with early pathologicalevents of Alzheimer’s disease.更多还原

【Abstract】 Co-injection of wortmannin（inhibitor of phosphatidylinositol-3 kinase,PI3K）and GF109203X （inhibitor of protein kinase C,PKC）into the rat brain was found to induce spatial memory deficiency and enhance tau hyperphosphorylation in the hippocampus of rat brain.To establish a cell model with durative Alzheimer-like tau hyperphosphorylation in this study,we treated N2a neuroblastoma cells with wortmannin and GF109203X separately and simultaneously,and measured the glycogen synthase kinase 3（GSK-3） activity by γ-（32）^P-labeling and the level of tau phosphorylation by Western blotting.It was found that the application of wortmannin alone only transitorily increased the activity of GSK-3（about 1 h）and the level of tau hyperphosphorylation at Ser³⁹⁶/Ser⁴⁰⁴ and Ser¹⁹⁹/Ser²⁰² sites（no longer than 3 h）;however,a prolonged and intense activation of GSK-3（over 12 h）and enhanced tan hyperphosphorylation（about 24 h）were observed when these two selective kinase inhibitors were applied together.We conclude that the simultaneous inhibition of PI3K and PKC can induce GSK-3 overactivation,and further strengthen and prolong the Alzheimer- like tau hyperphosphorylation in N2a cells,suggesting the establishment of a cell model with early pathological events of Alzheimer’s disease.更多还原