title: p53 down-regulation: a new molecular mechanism involved in ischaemic preconditioning.
abstract: Ischaemic preconditioning is associated with the activation of prosurvival mechanisms. Here we demonstrate that following a preconditioning protocol, the proapoptotic p53 is inactivated possibly via phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt)-murine double minute 2 (Mdm2) phosphorylation. Our data show that in preconditioned hearts Mdm2 was significantly phosphorylated, and wortmannin (a PI3K inhibitor) abrogated this effect (Western blotting). Also in preconditioned hearts p53 was shown to be bound to phospho-Mdm2 (co-immunoprecipitation). Furthermore, pifithrin alpha (a p53 inhibitor), administered to isolated perfused hearts prior to ischaemia, significantly attenuated the infarction. In conclusion our results suggest that p53 is implicated in ischaemia/reperfusion injury and that preconditioning counterbalances this effect via PI3K-Akt-Mdm2 phosphorylation.
authors.affiliation: The Hatter Institute and Centre for Cardiology, University College London Medical School, London WC1E 6DB, UK.
authors.forename: Mihaela M
authors.initials: MM
authors.lastname: Mocanu
authors.forename: Derek M
authors.initials: DM
authors.lastname: Yellon
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D052160:Benzothiazoles; D015152:Blotting, Northern; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism; D017202:Myocardial Ischemia / Q000378:metabolism*; D015425:Myocardial Reperfusion; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051736:Proto-Oncogene Proteins c-mdm2; D051381:Rats; D017207:Rats, Sprague-Dawley; D013844:Thiazoles / Q000494:pharmacology; D014050:Toluene / Q000031:analogs & derivatives* / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D052160:Benzothiazoles; D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D051736:Proto-Oncogene Proteins c-mdm2; D013844:Thiazoles; D014050:Toluene; D016159:Tumor Suppressor Protein p53; D000077191:Wortmannin; C121565:pifithrin; C497208:Mdm2 protein, rat; C494920:Akt1 protein, rat