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OBJECTIVE The aim of the present study was to investigate the effect of cornel iridoid glycoside(CIG)on tau hyperphosphorylation induced by wortmannin(WT)and GF-109203X(GFX)and the underlying mechanisms.METHODS Human neuroblastoma SK-N-SH cells were pre-incubated with CIG(50,100,and 200μg·mL-1,respectively)for 24 h,and then exposed to WT 10μmol·L-1 and GFX 10μmol·L-1for 3hafter washing out CIG.Immuno-fluorescence was used to observe the microtubular cytoskeleton of the cultured cells.Western blotting was used to measure the phosphorylation level of tau protein,glycogen synthase kinase 3β(GSK-3β)and protein phosphatase 2A(PP2A).The activity of PP2 Awas detected by a biochemical assay.RESULTS Pre-incubation of CIG significantly attenuated the WT/GFX-induced tau hyperphosphorylation at the sites of Thr205,Thr212,Ser214,Thr217Ser396 and PHF-1,and improved the damage of morphology and microtubular cytoskeleton of the cells.CIG did not prevent the decrease in p-AKT-ser473 and pGSK3β-ser9 induced by WT/GFX.However,CIG significantly elevated the activity of PP2 Aby reducing the demethylation of PP2AC at Leu309 and the ratio of PME-1/LCMT in the WT/GFX-treated cells.CONCLUSION CIG obviously attenuated WT/GFX-induced tau hyper-phosphorylation at multiple AD-related sites by increasing the activity of PP2A.The mechanism may be involved in the reduced demethylation of PP2 Avia down regulating the ratio of PME/LCMT.
OBJECTIVE The aim of the present study was to investigate the effect of cornel iridoid glycoside (CIG) on tau hyperphosphorylation induced by wortmannin (WT) and GF-109203X (GFX) and the underlying mechanisms. METHODS Human neuroblastoma SK-N-SH cells were pre-incubated with CIG (50,100, and 200μg · mL-1, respectively) for 24 h, and then exposed to WT 10μmol·L-1 and GFX 10μmol·L-1for 3hafter washing out CIG.Immuno-fluorescence was used to observe the microtubular cytoskeleton of the cultured cells. Western blotting was used to measure the phosphorylation level of tau protein, glycogen synthase kinase 3β (GSK-3β) and protein phosphatase 2A (PP2A). The activity of PP2 Awas detected by a biochemical assay .RESULTS Pre-incubation of CIG significantly attenuated the WT / GFX-induced tau hyperphosphorylation at the sites of Thr205, Thr212, Ser214, Thr217Ser396 and PHF-1, and improved the damage of morphology and microtubular cytoskeleton of the cells. CIG did not prevent the decrease in p-AKT-ser473 and pGSK3β -ser9 induced by WT / GFX.However, CIG significantly elevated the activity of PP2 Aby reducing the demethylation of PP2AC at Leu309 and the ratio of PME-1 / LCMT in the WT / GFX-treated cells. CONCLUSION CIGLY attenuated WT / GFX -induced tau hyper-phosphorylation at multiple AD-related sites by increasing the activity of PP2A.The mechanism may be involved in the reduced demethylation of PP2 Avia down regulating the ratio of PME / LCMT.