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

Abstract

BackgroundMyocardial 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 is crucial 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 ResultsSilencing capability of p‐shEGFR was assessed in EGFR‐GFP transiently transfected HEK293T cells. Four weeks after lentivirus injection into the left ventricular wall of Wistar rats, shRNA‐EGFR–injected hearts showed ≈60% reduction of EGFR protein expression compared with shRNA‐SCR–injected hearts. ErbB2 and ErbB4 expression did not change. The SFR to stretch evaluated in isolated papillary muscles was ≈130% of initial rapid phase in the shRNA‐SCR group, while it was blunted in shRNA‐EGFR–expressing muscles. Angiotensin II (Ang II)‐dependent Na+/H+ exchanger 1 activation was indirectly evaluated by intracellular pH measurements in bicarbonate‐free medium, demonstrating an increase in shRNA‐SCR–injected myocardium, an effect not observed in the silenced group. Ang II‐ or EGF‐triggered reactive oxygen species production was significantly reduced in shRNA‐EGFR–injected hearts compared with that in the shRNA‐SCR group. Chronic lentivirus treatment affected neither the myocardial basal redox state (thiobarbituric acid reactive substances) nor NADPH oxidase activity or expression. Finally, Ang II or EGF triggered a redox‐sensitive pathway, leading to p90RSK activation in shRNA‐SCR‐injected myocardium, an effect that was absent in the shRNA‐EGFR group.ConclusionsOur results provide evidence that specific EGFR activation after myocardial stretch is a key factor in promoting the redox‐sensitive kinase activation pathway, leading to SFR development.

The Role of ErbB Receptors in Infection

“…The ErbB receptor tyrosine kinase family consists of four members, ErbB1 (epidermal growth factor receptor, EGFR), ErbB2, ErbB3, and ErbB4, which are expressed on a plethora of cell types, including epithelial [1], endothelial [2], neuronal and glial [3], bone [4], adipose [5], liver [6], and cardiovascular cells [7]. Following ligand binding and activation, oligomerisation of ErbB family members occurs [8].…”

The slow force response to stretch: Controversy and contradictions

“…105 Thus, investigations have examined the role that EGFR transactivation plays in the SFR. EGFR phosphorylation measurably increases in response to stretch 86 and, in those cases where EGFR or the signalling pathway components immediately upstream or downstream are inhibited, 91,103,106 the SFR is blunted. The SFR 91 and increased EGFR phosphorylation 107 are prevented when the Src tyrosine kinase is blocked.…”

“…oxygen species EGFR 91,108 and GPCR 93,109-111 agonists increase nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-dependent reactive oxygen species (ROS) production. 103,112,113 Compromising EGFR or its mediators suppresses Ang II/ET-1-induced ROS formation 91,106 and, more relevantly, ROS production increases in response to stretch. 22,24,116 Prosser et al 24 demonstrated that this stretch-induced upregulation of NADPH oxidase activity was likely due, at least in part, to mechanical transduction of stretch via microtubules as well as the aforementioned GPCR pathway.…”

Participación del receptor de estrógenos acoplado a proteína G (GPER/GPR30) en los efectos no genómicos de aldosterona en el corazón

“…3.13 donde se observa la producción de ROS tanto en cardiomiocitos aislados como en tejido ventricular. El factor de crecimiento epidérmico (EGF) fue considerado activador de la NOX en tejido cardíaco (Nolly, Caldiz et al 2014, Brea, Diaz et al 2016. En nuestro trabajo el inhibidor del EGFR, AG1478 impide la producción de ROS a partir de NADPH oxidasa, indicando que el EGFR se encontraría corriente arriba de la misma en esta vía.…”