A Disintegrin and Metalloprotease-17 Regulates Pressure Overload-Induced Myocardial Hypertrophy and Dysfunction Through Proteolytic Processing of Integrin β1.

A disintegrin and metalloprotease-17 (ADAM17) belongs to a family of transmembrane enzymes, and it can mediate ectodomain shedding of several membrane-bound molecules. ADAM17 levels are elevated in patients with hypertrophic and dilated cardiomyopathy; however, its direct role in hypertrophic cardiomyopathy is unknown. Cardiomyocyte-specific ADAM17 knockdown mice (ADAM17(flox/flox)/αMHC-Cre; ADAM17(f/f)/Cre) and littermates with intact ADAM17 levels (ADAM17(f/f)) were subjected to cardiac pressure-overload by transverse aortic constriction. Cardiac function/architecture was assessed by echocardiography at 2 and 5 weeks post transverse aortic constriction. ADAM17 knockdown enhanced myocardial hypertrophy, fibrosis, more severe left ventricular dilation, and systolic dysfunction at 5 weeks post transverse aortic constriction. Pressure overload-induced upregulation of integrin β1 was much greater with ADAM17 knockdown, concomitant with the greater activation of the focal adhesion kinase pathway, suggesting that integrin β1 could be a substrate for ADAM17. ADAM17 knockdown did not alter other cardiomyocyte integrins, integrin α5 or α7, and HB-EGF (heparin-bound epidermal growth factor), another potential substrate for ADAM17, remained unaltered after pressure overload. ADAM17-mediated cleavage of integrin β1 was confirmed by an in vitro assay. Intriguingly, ADAM17 knockdown did not affect the myocardial hypertrophy induced by a subpressor dose of angiotensin II, which occurs independent from the integrin β1-mediated pathway. ADAM17-knockdown enhanced the hypertrophic response to cyclic mechanical stretching in neonatal rat cardiomyocytes. This study reports a novel cardioprotective function for ADAM17 in pressure overload cardiomyopathy, where loss of ADAM17 promotes hypertrophy by reducing the cleavage of cardiac integrin β1, a novel substrate for ADAM17. This function of ADAM17 is selective for pressure overload-induced myocardial hypertrophy and dysfunction, and not agonist-induced hypertrophy.