L Clau-induced Tau Protein Hyperphosphorylation Mechanism Of Inhibition Of Oa And A¦Â

Alzheimer's disease, a neurodegenerative disease, is most common in aged people. The main clinical symptoms of AD are progessive memory and other cognitive function decline and mental deterioration. AD is neuropathologically characterized by senile plaque in which the main component is β-amyloid, neurofibrillary tangle and neuron loss in nervous system.Clausenamide is a new compound isolated from clausena lansium Lour skells and its natural structure is similar to piracetam and now is synthesized. Hyperphosphorylated tau is the major component of paired helical filaments in neurofibrillary lesions associated with Alzheimers's disease. Hyperphosphorylation reduces the affinity of tau to microtubules and is thought to be a critical event in the pathogenesis of this disease. The aim of this study is to investigae the mechanism of (-)clausenamide inhibited tau hyperphosphorylation induced by okadaic acid and β-amyloid peptide.In vitro strudy, okadaic acid, a potent inhibitor of PP-2A and PP-1 was used to induce tau hyperphosphorylation and apoptosis in SH-SY5Y neuroblastoma cells at the concentration of 75nM, the effects of (-)clausenamide (10^-6,10^-7,10^-8mol/L) and lithium(10^-2,10^-3mol/L) was detected with MTT, LDH assay and Hoechst33258 staining. Western blotting method was used to investigate their influence on GSK expressing and activity as well as abnormal phosphorylation of micortubule associated protein.The result showed (-)clausenamide and lithium could significantly decrease the rate of cell death from MTT,LDH assay and apoptosis from the staining of Hoechst33258. Western blotting experiment showed lithium (10mmol/L) and (-)clausenamide (10^-8mol/L) increase the 9-Ser phosphorylation of GSK-3β and 21-Ser phosphorylated for GSK-3α, the phosphorylation of these sites is believed to inhibit the activity of GSK-3. The experiment also showed the expressing of GSK-3 doesn't change significantly and the stain of AT-8 antibody is reduced which reacts specially with abnormal phosphorylated sites of Ser199/202 in tau protein.Senile plaques, which plays an important role in the pathogenesis of AD, is initiated by the deposition of β-amyloid peptide, Aβ is believed to induce the...