Berberine attenuates calyculin A-induced cytotoxicity and Tau hyperphosphorylation in HEK293 cells.

The Chinese herb berberine has versatile health effects. Recent reports indicate that berberine has the potential to prevent and treat Alzheimer's disease (AD). In the present study, we employed tau-expressing HEK293 cells (HEK293/tau) treated with calyculin-A as a cellular model to investigate the roles of berberine in cell viability, tau phosphorylation, and oxidative stress. We found a significant reduction of calyculin A-induced tau hyperphosphorylation at Ser198/199/202, Ser396, Ser404, Thr205, and Thr231 24 h after treatment with 20 μg/ml berberine. Berberine also restored protein phosphates 2A activity and reversed glycogen synthase kinase-3β (GSK-3β) activation, as determined by phosphatase activity assay and GSK-3β phosphorylation at Tyr216 and Ser9, respectively. Furthermore, berberine reversed both the increase of malondialdehyde and the decrease of superoxide dismutase activity induced by calyculin A, indicating its role in anti-oxidative stress. Our findings suggest that berberine may be a potential therapeutic drug for AD.