title: Activation of Src protein tyrosine kinase plays an essential role in urocortin-mediated cardioprotection.
abstract: Urocortin is a 40 amino acid peptide of the corticotrophin-releasing factor (CRF) family that is synthesized and released by cardiac myocytes. Endogenous urocortin expression is increased during ischemia/reperfusion (I/R) and addition of exogenous urocortin reduces cell death caused by I/R injury. Studies have also showed that the protective action of urocortin is mediated by the activation of ERK1/2. We discovered that a non-receptor tyrosine kinase, Src, is involved in the urocortin-induced activation of ERK1/2 in mouse atrial HL-1 myocytes. The selective Src family kinase inhibitor, PP2, reduced the urocortin-induced phosphorylation of ERK1/2, and so did the expression of a dominant-negative mutant of Src in transfected HL-1 cells. Inhibition of Src by PP2 also reduced urocortin's protective effects in HL-1 cells after hypoxia/reoxygenation (H/R), as assessed by flow cytometry and caspase-3 activation assay. Titration studies indicated that as little as 10(-8)M urocortin was sufficient to induce Src activation. Maximal phosphorylation/activation of Src and ERK1/2 were both detected after 5 min incubation with urocortin. These effects of urocortin were largely mediated by CRF receptor-1, although a minor contribution of CRF receptor-2 cannot be excluded. Here we report for the first time that short-term treatment with urocortin causes rapid phosphorylation of Src, and that the urocortin-activated Src kinase serves as an upstream modulator of ERK1/2 activation, playing an essential role in urocortin-mediated cardioprotection.
authors.affiliation: Center for Heart and Vessel Preclinical Studies, St. John Hospital & Medical Center, USA.
authors.forename: Zhaokan
authors.initials: Z
authors.lastname: Yuan
authors.forename: Roy
authors.initials: R
authors.lastname: McCauley
authors.forename: Carol
authors.initials: C
authors.lastname: Chen-Scarabelli
authors.forename: Kadija
authors.initials: K
authors.lastname: Abounit
authors.forename: Anastasis
authors.initials: A
authors.lastname: Stephanou
authors.forename: Sean P
authors.initials: SP
authors.lastname: Barry
authors.forename: Richard
authors.initials: R
authors.lastname: Knight
authors.forename: Samuel F
authors.initials: SF
authors.lastname: Saravolatz
authors.forename: Louis D
authors.initials: LD
authors.lastname: Saravolatz
authors.forename: Berkin O
authors.initials: BO
authors.lastname: Ulgen
authors.forename: Gabriele M
authors.initials: GM
authors.lastname: Scarabelli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Faggian
authors.forename: Alessandro
authors.initials: A
authors.lastname: Mazzucco
authors.forename: Louis
authors.initials: L
authors.lastname: Saravolatz
authors.forename: Tiziano M
authors.initials: TM
authors.lastname: Scarabelli
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006321:Heart / Q000187:drug effects / Q000502:physiology; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism; D054832:Urocortins / Q000494:pharmacology* / Q000502:physiology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D000099052:CRF Receptor, Type 1
chemical_list: C101531:CRF receptor type 2; D002316:Cardiotonic Agents; D047428:Protein Kinase Inhibitors; D018019:Receptors, Corticotropin-Releasing Hormone; D054832:Urocortins; D000099052:CRF Receptor, Type 1; D019061:src-Family Kinases; D048052:Mitogen-Activated Protein Kinase 3