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

BREA, MARÍA SOLEDAD; CALDIZ, CLAUDIA; PÉREZ, NÉSTOR GUSTAVO; ESCUDERO, DAIANA; MORGAN, PATRICIO EDUARDO; ESCUDERO, DAIANA; MORGAN, PATRICIO EDUARDO; DÍAZ, ROMINA GISEL; PORTIANSKY, ENRIQUE LEO; DÍAZ, ROMINA GISEL; PORTIANSKY, ENRIQUE LEO; BREA, MARÍA SOLEDAD; CALDIZ, CLAUDIA; PÉREZ, NÉSTOR GUSTAVO

Journal of the American Heart Association

American Heart Association

Lugar: Dallas; Año: 2016 vol. 4

2047-9980

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 (EGF) receptor (EGFR or ErbB1) activation iscrucial for SFR development. Pharmacological inhibitors could block ErbB4, a member of the ErbB family 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(small hairpin RNA [shRNA]-EGFR).Methods and Results. Silencing capability of p-shEGFR was assessed in EGFR-GFP transiently transfected HEK293T cells. Fourweeks after lentivirus injection into the left ventricular wall of Wistar rats, shRNA-EGFR?injected hearts showed 60% reduction ofEGFR protein expression compared with shRNA-SCR?injected hearts. ErbB2 and ErbB4 expression did not change. The SFR tostretch evaluated in isolated papillary muscles was 130% of initial rapid phase in the shRNA-SCR group, while it was blunted inshRNA-EGFR?expressing muscles. Angiotensin II (Ang II)-dependent Na+/H+ exchanger 1 activation was indirectly evaluated byintracellular pH measurements in bicarbonate-free medium, demonstrating an increase in shRNA-SCR?injected myocardium, aneffect not observed in the silenced group. Ang II- or EGF-triggered reactive oxygen species production was significantly reduced inshRNA-EGFR?injected hearts compared with that in the shRNA-SCR group. Chronic lentivirus treatment affected neither themyocardial basal redox state (thiobarbituric acid reactive substances) nor NADPH oxidase activity or expression. Finally, Ang II orEGF triggered a redox-sensitive pathway, leading to p90RSK activation in shRNA-SCR-injected myocardium, an effect that wasabsent in the shRNA-EGFR group.Conclusions. Our results provide evidence that specific EGFR activation after myocardial stretch is a key factor in promoting theredox-sensitive kinase activation pathway, leading to SFR development.