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ISSN
1672-9145
Acta Biochim Biophys Sin
2005, 37(5): 349–354 CN 31-1940/Q
Prolonged Alzheimer-like Tau Hyperphosphorylation Induced by
Simultaneous Inhibition of Phosphoinositol-3 Kinase and Protein Kinase C in N2a
cells
Guo-Gang XU, Yan-Qiu DENG, Shi-Jie LIU, Hong-Lian LI, and Jian-Zhi WANG*
Department of Pathophysiology, Institute of Neuroscience, Tongji
Medical College, Huazhong University of Science and Technology, Wuhan 430030,
China
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
g–32P-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 tau
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.
Key words Alzheimer’s disease
(AD); tau; glycogen synthase kinase 3 (GSK-3); protein kinase C (PKC);
phosphatidylinositol-3 kinase (PI3K); N2a cells
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Received: January 13, 2005 Accepted: March 11, 2005
This work was supported by grants from the National Natural Science
Foundation of China (30430270, 30472030 and 30400068), Science and Technology
Committee of China (G1999054007) and National Educational Committee of China
(2001-171)
*Corresponding author: Tel, 86-27-83692625; Fax, 86-27-83693883;
E-mail, [email protected]