title: Sustained activation of p42/p44 mitogen-activated protein kinase during recovery from simulated ischaemia mediates adaptive cytoprotection in cardiomyocytes.
abstract: Delayed cytoprotection (preconditioning) occurs 24 h after sublethal simulated ischaemia and reperfusion (SI/R) in neonatal rat ventricular cardiomyocytes. SI/R was used to investigate the role of activation of mitogen-activated protein kinases (MAPKs), stress-activated protein kinases (SAPKs) and phosphoinositide 3-kinase-dependent protein kinase B (PKB)/Akt in cytoprotection. SI resulted in transient dual (Thr/Tyr) phosphorylation of p42/p44-MAPK and p38-MAPK, weak phosphorylation of p46/p54-SAPK, but no phosphorylation of PKB. 'Reperfusion' caused further transient phosphorylation of p38-MAPK, but sustained phosphorylation of p42/p44-MAPK (lasting 4 h) and of Ser(473) of PKB (lasting 2 h). Furthermore, SI/R (24 h) induced delayed protection against lethal SI, as determined by an increase in cell viability ¿bioreduction of MTT [3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide]¿ and a decrease in cell injury (release of creatine kinase). Both protection and phosphorylation of p42/p44-MAPK were blocked by the MEK-1/2 (MAPK/Erk kinase-1/2) inhibitor PD98059 (50 microM) when given during SI/R, but not when given during SI alone. The p38-MAPK inhibitor SB203580 (10 microM) blocked the p38-MAPK-dependent phosphorylation of activating transcription factor 2 in vitro, and the phosphoinositide 3-kinase inhibitor wortmannin (100 nM) blocked PKB phosphorylation on Ser(473). However, neither SB203580 nor wortmannin had any effect on delayed protection. Therefore sustained activation of p42/p44-MAPK during simulated 'reperfusion' following sublethal SI mediates preconditioning in cardiomyocytes independently of transient activation of p38-MAPK or sustained activation of PKB.
authors.affiliation: Department of Cardiology, King's College London, The Rayne Institute, St Thomas' Hospital, Lambeth Palace Road, London SE1 7EH, U.K.
authors.forename: A
authors.initials: A
authors.lastname: Punn
authors.forename: J W
authors.initials: JW
authors.lastname: Mockridge
authors.forename: S
authors.initials: S
authors.lastname: Farooqui
authors.forename: M S
authors.initials: MS
authors.lastname: Marber
authors.forename: R J
authors.initials: RJ
authors.lastname: Heads
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D004789:Enzyme Activation; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017202:Myocardial Ischemia / Q000201:enzymology*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000201:enzymology / Q000473:pathology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019869:Phosphatidylinositol 3-Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases