Cardiomyocyte A Disintegrin And Metalloproteinase 17 (ADAM17) Is Essential in Post–Myocardial Infarction Repair by Regulating Angiogenesis

BACKGROUND: A disintegrin and metalloproteinase 17 (ADAM17) is a membrane-bound enzyme that mediates shedding of many membrane-bound molecules, thereby regulating multiple cellular responses. We investigated the role of cardiomyocyte ADAM17 in myocardial infarction (MI). METHODS AND RESULTS: Cardiomyocyte-specific ADAM17 knockdown mice (ADAM17(flox/flox)/α-MHC-Cre; f/f/Cre) and parallel controls (ADAM17(flox/flox); f/f) were subjected to MI by ligation of the left anterior descending artery. Post MI, f/f/Cre mice showed compromised survival, higher rates of cardiac rupture, more severe left ventricular dilation, and suppressed ejection fraction compared with parallel f/f-MI mice. Ex vivo ischemic injury (isolated hearts) resulted in comparable recovery in both genotypes. Myocardial vascular density (fluorescent-labeled lectin perfusion and CD31 immunofluorescence staining) was significantly lower in the infarct areas of f/f/Cre-MI compared with f/f-MI mice. Activation of vascular endothelial growth factor receptor 2 (VEGFR2), its mRNA, and total protein levels were reduced in infarcted myocardium in ADAM17 knockdown mice. Transcriptional regulation of VEGFR2 by ADAM17 was confirmed in cocultured cardiomyocyte-fibroblast as ischemia-induced VEGFR2 expression was blocked by ADAM17-siRNA. Meanwhile, ADAM17-siRNA did not alter VEGFA bioavailability in the conditioned media. ADAM17 knockdown mice (f/f/Cre-MI) exhibited reduced nuclear factor-κB activation (DNA binding) in the infarcted myocardium, which could underlie the suppressed VEGFR2 expression in these hearts. Post MI, inflammatory response was not altered by ADAM17 downregulation. CONCLUSIONS: This study highlights the key role of cardiomyocyte ADAM17 in post-MI recovery by regulating VEGFR2 transcription and angiogenesis, thereby limiting left ventricular dilation and dysfunction. Therefore, ADAM17 upregulation, within the physiological range, could provide protective effects in ischemic cardiomyopathy.