Essential role of EGFR in cardioprotection and signaling responses to A1 adenosine receptors and ischemic preconditioning

Abstract

ransactivation of epidermal growth factor receptor (EGFR) may contribute to specific protective responses (eg. mediated by δ-opioid, bradykinin, or muscarinic receptors). No studies have assessed EGFR involvement in cardioprotection mediated by adenosine receptors (ARs), and the role of EGFR in ischemic preconditioning (IPC) is unclear. We tested EGFR, matrix metalloproteinase (MMP) and heparin-binding EGF (HB-EGF) dependencies of functional protection via A(1)AR agonism or IPC. Pre-treatment of mouse hearts with 100 nM of A(1)AR agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) or IPC (3 x 1.5 min ischemia/2 min reperfusion) substantially improved recovery from 25 min ischemia, reducing left ventricular diastolic dysfunction up to 50% and nearly doubling pressure development and +dP/dt. Benefit with both CCPA and IPC was eliminated by inhibitors of EGFR tyrosine kinase (0.3 μM AG1478), MMP (0.3 μM GM6001) or HB-EGF ligand (0.3 ng/ml CRM197), none of which independently altered post-ischemic outcome. Phosphorylation of myocardial EGFR, Erk1/2 and Akt increased 2- to 3-fold during A(1)AR agonism, with responses blocked by AG1478, GM6001 and CRM197. Studies in HL-1 myocytes confirm A(1)AR dependent Erk1/2 phosphorylation is negated by AG1478 or GM6001, and reduced with CRM197 (as was Akt activation). These data collectively reveal that A(1)AR- and IPC-mediated functional protection is entirely EGFR- and MMP-dependent, potentially involving HB-EGF ligand. Myocardial survival kinase activation (Erk1/2, Akt) by A1AR agonism is similarly MMP/HB-EGF/EGFR dependent. Thus, MMP-mediated EGFR activation appears essential to cardiac protection and signaling via A(1)ARs and preconditioning.