title: Glycogen synthase kinase-3beta plays a pro-apoptotic role in beta-adrenergic receptor-stimulated apoptosis in adult rat ventricular myocytes: Role of beta1 integrins.
abstract: Beta-adrenergic receptor (beta-AR) stimulation induces apoptosis in adult rat ventricular myocytes (ARVM). beta1 integrin signaling plays a protective role in beta-AR-stimulated apoptosis. Glycogen synthase kinase-3beta (GSK-3beta), a multifunctional serine/threonine kinase, negatively regulates cardiac hypertrophy. Here we show that beta-AR stimulation (isoproterenol; 15 min) increases tyr(216) phosphorylation and GSK-3beta activity. Inclusion of LiCl, inhibitor of GSK-3beta, in the reaction mix or expression of catalytically inactive GSK-3beta (KM-GSK) inhibited beta-AR-stimulated GSK-3beta activity. Inhibition of tyrosine kinase using genistein or chelation of intracellular Ca(2+) using BAPTA-AM inhibited beta-AR-stimulated increases in tyr(216) phosphorylation and GSK-3beta activity. Inhibition of GSK-3beta using pharmacological inhibitors or infection with KM-GSK decreased beta-AR-stimulated cytosolic cytochrome C release and apoptosis. Expression of beta1 integrins increased ser(9) phosphorylation and inhibited beta-AR-stimulated increase in GSK-3beta activity. Wortmannin, inhibitor of PI3-kinase, reversed the effects of beta1 integrins on GSK-3beta activity and apoptosis. Purified active matrix metalloproteinase-2 (MMP-2), shown to interfere with beta1 integrin signaling, increased GSK-3beta activity, while inhibition of MMP-2 inhibited beta-AR-stimulated increases in GSK-3beta activity. beta-AR stimulation induced nuclear accumulation of GSK-3beta. beta-AR stimulation (3 h) increased the expression of transcription factor Gadd153 (growth arrest- and DNA damage-inducible gene 153). These data suggest that beta-AR stimulation increases GSK-3beta activity. Activation of GSK-3beta plays a pro-apoptotic role in beta-AR-stimulated apoptosis via the involvement of mitochondrial death pathway. beta1 integrins inactivate GSK-3beta and play an anti-apoptotic role via the involvement of PI3-kinase pathway. The apoptotic effects of GSK-3beta may be mediated, at least in part, via its nuclear localization and induction of pro-apoptotic genes, such as Gadd153.
authors.affiliation: Department of Physiology, James H Quillen College of Medicine, James H Quillen Veterans Affairs Medical Center, East Tennessee State University, PO Box 70576, Johnson City, TN 37614, USA.
authors.forename: Bindu
authors.initials: B
authors.lastname: Menon
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Johnson
authors.forename: Robert S
authors.initials: RS
authors.lastname: Ross
authors.forename: Mahipal
authors.initials: M
authors.lastname: Singh
authors.forename: Krishna
authors.initials: K
authors.lastname: Singh
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism*; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D008297:Male; D032342:Muscle Cells / Q000166:cytology* / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D051742:Transcription Factor CHOP / Q000378:metabolism
chemical_list: D045304:Cytochromes c; D004791:Enzyme Inhibitors; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D019012:Integrin beta1; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011943:Receptors, Adrenergic, beta; D051742:Transcription Factor CHOP; C000605508:Gsk3b protein, rat