The binding and phosphorylation of Thr231 is critical for Tau’s hyperphosphorylation and functional regulation by glycogen synthase kinase 3β
Article first published online: 29 JUN 2007
© 2007 The Authors. Journal Compilation © 2007 International Society for Neurochemistry
Journal of Neurochemistry
Volume 103, Issue 2, pages 802–813, October 2007
How to Cite
Lin, Y.-T., Cheng, J.-T., Liang, L.-C., Ko, C.-Y., Lo, Y.-K. and Lu, P.-J. (2007), The binding and phosphorylation of Thr231 is critical for Tau’s hyperphosphorylation and functional regulation by glycogen synthase kinase 3β. Journal of Neurochemistry, 103: 802–813. doi: 10.1111/j.1471-4159.2007.04792.x
- Issue published online: 29 JUN 2007
- Article first published online: 29 JUN 2007
- Received January 31, 2007; revised manuscript received April 25, 2007; accepted June 13, 2007.
- Alzheimer’s disease;
- glycogen synthase kinase 3β;
Neuropathological hallmarks of Alzheimer’s disease are extracellular senile plaques and intracellular neurofibrillary lesions. The neurofibrillary lesions mainly consist of the hyperphosphorylated microtubule-associated protein Tau predominantly expressed in the axon of CNS neurons. Hyperphosphorylation of Tau negatively affects its binding to tubulin and decreases the capacity to promote microtubule assembly. Among a number of proline-directed kinases capable of phosphorylating paired helical filament-Tau, glycogen synthase kinase 3β (GSK3β) was first identified as a Tau protein kinase I and has been demonstrated to phosphorylate Tau both in vivo and in vitro. However, the phosphorylation mechanism of Tau by GSK3β remained unclear. In this study, we show that the T231 is the primary phosphorylation site for GSK3β and the Tau227–237 (AVVRTPPKSPS) derived from Tau containing T231P232 motif is identified as the GSK3β binding site with high affinity of a Kd value 0.82 ± 0.16 μmol/L. Our results suggest that direct binding and phosphorylation of T231P232 motif by GSK3β induces conformational change of Tau and consequentially alters the inhibitory activity of its N-terminus that allows the phosphorylation of C-terminus of Tau by GSK3β. Furthermore, hyperphosphorylation reduces Tau’s ability to promote tubulin assembly and to form bundles in N18 cells. T231A mutant completely abolishes Tau phosphorylation by GSK3β and retains the ability to promote tubulin polymerization and bundle formation. Taken together, these results suggest that phosphorylation of T231 by GSK3β may play an important role in Tau’s hyperphosphorylation and functional regulation.