Activation of Src protein tyrosine kinase plays an essential role in urocortin-mediated cardioprotection.
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.
Yuan
Zhaokan
Z
Center for Heart and Vessel Preclinical Studies, St. John Hospital & Medical Center, USA.
McCauley
Roy
R
Chen-Scarabelli
Carol
C
Abounit
Kadija
K
Stephanou
Anastasis
A
Barry
Sean P
SP
Knight
Richard
R
Saravolatz
Samuel F
SF
Saravolatz
Louis D
LD
Ulgen
Berkin O
BO
Scarabelli
Gabriele M
GM
Faggian
Giuseppe
G
Mazzucco
Alessandro
A
Saravolatz
Louis
L
Scarabelli
Tiziano M
TM
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
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