GSK-3 mediates the okadaic acid-induced modification of collapsin response mediator protein-2 in human SK-N-SH neuroblastoma cells
✍ Scribed by Mei-Hui Ni; Chih-Ching Wu; Wen-Hsiung Chan; Kun-Yi Chien; Jau-Song Yu
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 378 KB
- Volume
- 103
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Abstract
Collapsin response mediator protein‐2 (CRMP‐2), a phosphoprotein involved in axonal outgrowth and microtubule dynamics, is aberrantly phosphorylated in Alzheimer's disease (AD) brain. Alteration of glycogen synthase kinase‐3 (GSK‐3) activity is associated with the pathogenesis of AD. Here, we show that CRMP‐2 is one of the major substrates for GSK‐3 in pig brain extracts. Both GSK‐3α and 3β phosphorylate purified pig brain CRMP‐2 and significantly alter its mobility in SDS‐gels, resembling the CRMP‐2 modification observed in AD brain. Interestingly, this modification can be detected in SK‐N‐SH neuroblastoma cells treated with a phosphatase inhibitor, okadaic acid (OA), and GSK‐3 inhibitors completely block this OA‐induced event. Knockdown of both GSK‐3α and 3β, but not either kinase alone, impairs OA‐induced modification of CRMP‐2. Mutation of Ser‐518 or Ser‐522 of CRMP‐2, which are highly phosphorylated in AD brain, to Ala blocks the OA‐induced modification of CRMP‐2 in SK‐N‐SH cells. Ser‐522 prephosphorylated by Cdk5 is required for subsequent GSK‐3α‐mediated phosphorylation of CRMP‐2 in vitro. Collectively, our results demonstrate for the first time that OA can induce phosphorylation of CRMP‐2 in SK‐N‐SH cells at sites aberrantly phosphorylated in AD brain, and both GSK‐3α and 3β and Ser‐522 kinase(s) are involved in this process. J. Cell. Biochem. 103: 1833–1848, 2008. © 2007 Wiley‐Liss, Inc.