title: Membrane depolarization induces the undulating phosphorylation/dephosphorylation of glycogen synthase kinase 3beta, and this dephosphorylation involves protein phosphatases 2A and 2B in SH-SY5Y human neuroblastoma cells.
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 3beta (GSK-3beta) in this process has not been elucidated. Thus, this study was performed to examine whether membrane depolarization can regulate the phosphorylation of GSK-3beta 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-3beta 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 beta-catenin contents showed a temporal pattern similar to that of the Ser-9 phosphorylation of GSK-3beta. Treatment with wortmannin or calphostin C or the expression of dominant negative Akt inhibited phosphorylation of GSK-3beta 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-3beta 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-3beta dephosphorylation following membrane depolarization, and the amounts of co-immunoprecipitated GSK-3beta and PP2A changed in parallel with GSK-3beta dephosphorylation. Our study demonstrated that KCl-induced depolarization caused undulating GSK-3beta phosphorylation/dephosphorylation, which was regulated for the most part by phosphatidylinositol 3-kinase and Akt (phosphorylation) and PP2A and PP2B (dephosphorylation), respectively.
authors.affiliation: Department of Biochemistry and Department of Psychiatry, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-799, Korea.
authors.forename: Yun-Il
authors.initials: YI
authors.lastname: Lee
authors.forename: MiRan
authors.initials: M
authors.lastname: Seo
authors.forename: Yeni
authors.initials: Y
authors.lastname: Kim
authors.forename: So-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Ung Gu
authors.initials: UG
authors.lastname: Kang
authors.forename: Yong-Sik
authors.initials: YS
authors.lastname: Kim
authors.forename: Yong-Sung
authors.initials: YS
authors.lastname: Juhnn
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D019703:Calcineurin / Q000737:chemistry*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005909:Glioblastoma / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D009281:Naphthalenes / Q000494:pharmacology; D016716:PC12 Cells; D010749:Phosphoprotein Phosphatases / Q000737:chemistry*; D010766:Phosphorylation; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D012694:Serine / Q000737:chemistry; D013912:Threonine / Q000737:chemistry; D013997:Time Factors; D014162:Transfection; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D004791:Enzyme Inhibitors; D009281:Naphthalenes; D013912:Threonine; D012694:Serine; D011189:Potassium Chloride; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; C058819:calphostin C; D002118:Calcium; D000077191:Wortmannin