Epidermal Growth Factor Receptor Silencing Blunts the Slow Force Response to Myocardial Stretch

BREA MS; DIAZ RG; ESCUDERO DS; CALDIZ CI; PORTIANSKY EL; MORGAN PE; PÉREZ NG

Journal of the American Heart Association (JAHA)

American Heart Association

Lugar: Boston, MA; Año: 2016

Background. Myocardial stretch increases force biphasically: the Frank?Starling mechanism followed by the slow force response (SFR). Based on pharmacological strategies, we proposed that epidermal growth factor receptor (EGFR) activation is crucial for the SFR development. Pharmacological inhibitors could block ErbB4, a family member present in the adult heart. We aimed to specifically test the role of EGFR activation after stretch, with an interference RNA incorporated into a lentiviral vector (shRNA-EGFR). Methods and Results. Silencing capability of p-shEGFR was assessed on EGFR-GFP transiently transfected HEK293T cells. Four weeks after lentivirus injection into Wistar rat left ventricular wall, shRNA-EGFR-injected hearts showed ~60% reduction of EGFR protein expression compared to shRNA-SCR. ErbB2 and ErbB4 expression did not change. The SFR to stretch evaluated in isolated papillary muscles was ~130% of initial rapid phase in shRNA-SCR group, while it was blunted in shRNA-EGFR-expressing muscles. Ang II-dependent NHE1 activation was indirectly evaluated by pHi measurements in bicarbonate-free medium, evidencing an increase in shRNA-SCR injected myocardium, effect not observed in the silenced group. Ang II or EGF-triggered ROS production was significantly reduced in shRNA-EGFR-injected hearts compared to shRNA-SCR. Chronic lentivirus treatment neither affected myocardial basal redox state (T-BARS) nor NADPH-oxidase activity or expression. Finally, Ang II or EGF triggered redox sensitive pathway leading to p90RSK activation in shRNA-SCR-injected myocardium, effect that was absent in the shRNA-EGFR group.Conclusions. Our results provide evidence that specific EGFR activation after myocardial stretch is a key factor to promote redox-sensitive kinase activation pathway leading to SFR development.