Membrane depolarization induces the undulating phosphorylation/ dephosphorylation of glycogen synthase kinase 3β, and this dephosphorylation involves protein phosphatases 2A and 2B in SH-SY5Y human neuroblastoma cells

Yun Il Lee, Mi Ran Seo, Yeni Kim, So Young Kim, Ung Gu Kang, Yong Sik Kim, Yong Sung Juhnn

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

Changes in plasma membrane electrical potential evoke signals that regulate the expressions of various genes in the nervous system. However, the role of glycogen synthase kinase 3β (GSK-3β) in this process has not been elucidated. Thus, this study was performed to examine whether membrane depolarization can regulate the phosphorylation of GSK-3β and to identify the molecular mechanisms involved in this regulation. The depolarization by treating with 100 mM KCl for 5 min resulted in the undulating phosphorylation of GSK-3β at Ser-9 in SH-SY5Y human neuroblastoma cells, in H19-7/ IGF-IR rat embryonic hippocampal cells, and in PC12 rat pheochromocytoma cells, but not in A172 human glioblastoma cells. Cellular β-catenin contents showed a temporal pattern similar to that of the Ser-9 phosphorylation of GSK-3β. Treatment with wortmannin or calphostin C or the expression of dominant negative Akt inhibited phosphorylation of GSK-3β at Ser-9 following the KCl-induced depolarization of SH-SY5Y cells. Moreover, pretreatment with okadaic acid or cyclosporin A blocked the dephosphorylation of GSK-3β at Ser-9 at 0, 15, and 30 min after KCl-induced depolarization, and the activity of protein phosphatases (PP) 2A and 2B increased at these times. Treatment with nifedipine or calcium-free medium inhibited GSK-3β dephosphorylation following membrane depolarization, and the amounts of co-immunoprecipitated GSK-3β and PP2A changed in parallel with GSK-3β dephosphorylation. Our study demonstrated that KCl-induced depolarization caused undulating GSK-3β phosphorylation/dephosphorylation, which was regulated for the most part by phosphatidylinositol 3-kinase and Akt (phosphorylation) and PP2A and PP2B (dephosphorylation), respectively.

Original languageEnglish
Pages (from-to)22044-22052
Number of pages9
JournalJournal of Biological Chemistry
Volume280
Issue number23
DOIs
StatePublished - 10 Jun 2005

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