title: Roles of phospho-GSK-3β in myocardial protection afforded by activation of the mitochondrial K ATP channel.
abstract: The aim of this study was to determine the roles of glycogen synthase kinase-3β (GSK-3β) in cardioprotection by activation of the mitochondrial ATP-sensitive K(+) channel (mK(ATP) channel). In isolated rat hearts, an mK(ATP) activator, diazoxide, and a GSK-3β inhibitor, SB216763, similarly limited infarct size and the combination of these agents did not afford further protection. The protection by pre-ischemic treatment with diazoxide was abolished by inhibition of protein kinase C-ε (PKC-ε) or phosphatidylinositol-3-kinase (PI3K) upon reperfusion. Infusion of a GSK-3β inhibitor (LiCl), but not diazoxide, during reperfusion limited infarct size. Inhibition of PKC-ε or PI3K did not affect the protection by LiCl. Diazoxide infusion alone did not induce GSK-3β phosphorylation. However, diazoxide infusion before ischemia increased mitochondrial phospho-GSK-3β level and reduced cyclophilin-D (CypD) binding to adenine nucleotide translocase (ANT) at 10 min after reperfusion. This diazoxide-induced GSK-3β phosphorylation was inhibited by blockade of the mK(ATP) channel before ischemia and by blockade of PKC-ε, PI3K or the adenosine A2b receptor at the time of reperfusion. Inhibition of GSK-3β by LiCl during reperfusion increased phospho-GSK-3β but had no significant effect on CypD-ANT binding. These results suggest that GSK-3β phosphorylation at the time of reperfusion by a PKC-ε, PI3K- and A2b receptor-dependent mechanism contributes to prevention of myocardial necrosis by pre-ischemic activation of the mK(ATP) channel. Inhibition of CypD-ANT interaction may contribute to mK(ATP)-induced myocardial protection, though it is not the sole mechanism of phospho-GSK-3β-mediated cytoprotection.
authors.affiliation: Division of Cardiology, Second Department of Internal Medicine, Sapporo Medical University School of Medicine, South-1 West-16, Chuo-ku, Sapporo 060-8543, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Terashima
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sato
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yano
authors.forename: Ole
authors.initials: O
authors.lastname: Maas
authors.forename: Takahito
authors.initials: T
authors.lastname: Itoh
authors.forename: Takayuki
authors.initials: T
authors.lastname: Miki
authors.forename: Masaya
authors.initials: M
authors.lastname: Tanno
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kuno
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Shimamoto
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Miura
mesh_terms: D058917:Adenosine A2 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins / Q000378:metabolism; D003981:Diazoxide / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006439:Hemodynamics / Q000187:drug effects; D015151:Immunoblotting; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000187:drug effects; D018021:Lithium Chloride / Q000494:pharmacology; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism; D009203:Myocardial Infarction / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D010477:Perfusion; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D051744:Protein Kinase C-epsilon / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000150:complications / Q000473:pathology
chemical_list: D058917:Adenosine A2 Receptor Antagonists; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins; D003981:Diazoxide; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D018021:Lithium Chloride; D000226:Mitochondrial ADP, ATP Translocases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D051744:Protein Kinase C-epsilon; C117780:mitochondrial K(ATP) channel; C000605508:Gsk3b protein, rat