title: Proapoptotic stimuli induce nuclear accumulation of glycogen synthase kinase-3 beta.
abstract: The goal of this study was to determine whether the intracellular distribution of the proapoptotic enzyme glycogen synthase kinase-3 beta (GSK-3 beta) is dynamically regulated by conditions that activate apoptotic signaling cascades. In untreated human neuroblastoma SH-SY5Y cells, GSK-3 beta was predominantly cytosolic, although a low level was also detected in the nucleus. The nuclear level of GSK-3 beta was rapidly increased after exposure of cells to serum-free media, heat shock, or staurosporine. Although each of these conditions caused changes in the serine 9 and/or tyrosine phosphorylation of GSK-3 beta, neither of these modifications was correlated with nuclear accumulation of GSK-3 beta. Heat shock and staurosporine treatments increased nuclear GSK-3 beta prior to activation of caspase-9 and caspase-3, and this nuclear accumulation of GSK-3 beta was unaltered by pretreatment with a general caspase inhibitor. The GSK-3 beta inhibitor lithium did not alter heat shock-induced nuclear accumulation of GSK-3 beta but increased the nuclear level of cyclin D1, indicating that cyclin D1 is a substrate of nuclear GSK-3 beta. Thus, the intracellular distribution of GSK-3 beta is dynamically regulated by signaling cascades, and apoptotic stimuli cause increased nuclear levels of GSK-3 beta, which facilitates interactions with nuclear substrates.
authors.affiliation: Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
authors.forename: G N
authors.initials: GN
authors.lastname: Bijur
authors.forename: R S
authors.initials: RS
authors.lastname: Jope
mesh_terms: D051033:Apoptosis Inducing Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects* / Q000201:enzymology; D019938:Cyclin D1 / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005420:Flavoproteins / Q000494:pharmacology*; D038362:Glycogen Synthase Kinase 3; D038341:Glycogen Synthase Kinases; D006358:Hot Temperature; D006801:Humans; D008094:Lithium / Q000494:pharmacology; D008565:Membrane Proteins / Q000494:pharmacology*; D010766:Phosphorylation; D012694:Serine / Q000378:metabolism; D019311:Staurosporine / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
chemical_list: C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D004791:Enzyme Inhibitors; D005420:Flavoproteins; D008565:Membrane Proteins; D019938:Cyclin D1; D014443:Tyrosine; D012694:Serine; D008094:Lithium; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3; D019311:Staurosporine