Loss of ACE2 Accelerates Pressure Overload-Induced Myocardial Oxidative Stress and Ventricular Dysfunction

Abstract

Introduction: Pressure overload activates the cardiac renin-angiotensin system (RAS) in association with myocardial oxidative stress and left ventricular dysfunction. The key peptidase action of angiotensin converting enzyme 2 (ACE2) is degradation of angiotensin (Ang) II to Ang (1–7), functioning effectively as a negative regulator of the RAS. Hypothesis: We hypothesized that ACE2 exerts its protective roles against myocardial oxidative stress and ventricular dysfunction by modulation of NADPH oxidase activity. Methods: Male wildtype (WT) mice, ACE2 knockout (KO) and ACE2/p47phox double KO mice of 10 weeks of age underwent aortic banding model of pressure-overload for 3 weeks. We characterized the functional, structural and molecular changes in the heart in response to pressure overload by echocardiography, TaqMan real-time PCR, Western blot analysis and assessed NADPH oxidase activity. Results: Compared with WT mice, loss of ACE2 resulted in a marked increase in pressure overload-induced myocardial oxidative stress in banded ACE2 KO mice, associated with decreased cardiac function, increased expression of hypertrophy markers (ANF and BNP) and elevated NADPH oxidase activities including p47phox, and Nox2 and Nox4 mRNA expression. These changes were linked with activation of PKCα protein and phosphorylation of the extracellular signal-regulated protein kinase (ERK1/2), Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling in ACE2 KO mice. Loss of p47 subunit prevented the increase in NADPH oxidase activity and attenuated the adverse remodeling in the ACE2 KO mice. Conclusions: Loss of ACE2 accelerates pressure-overload induced myocardial oxidative stress, ventricular dysfunction by activation of the NADPH oxidase subunits with the p47 subunit playing a key role. ACE2 suppresses the myocardial NADPH oxidase system possible by reducing Ang II levels. Introduction: Pressure overload activates the cardiac renin-angiotensin system (RAS) in association with myocardial oxidative stress and left ventricular dysfunction. The key peptidase action of angiotensin converting enzyme 2 (ACE2) is degradation of angiotensin (Ang) II to Ang (1–7), functioning effectively as a negative regulator of the RAS. Hypothesis: We hypothesized that ACE2 exerts its protective roles against myocardial oxidative stress and ventricular dysfunction by modulation of NADPH oxidase activity. Methods: Male wildtype (WT) mice, ACE2 knockout (KO) and ACE2/p47phox double KO mice of 10 weeks of age underwent aortic banding model of pressure-overload for 3 weeks. We characterized the functional, structural and molecular changes in the heart in response to pressure overload by echocardiography, TaqMan real-time PCR, Western blot analysis and assessed NADPH oxidase activity. Results: Compared with WT mice, loss of ACE2 resulted in a marked increase in pressure overload-induced myocardial oxidative stress in banded ACE2 KO mice, associated with decreased cardiac function, increased expression of hypertrophy markers (ANF and BNP) and elevated NADPH oxidase activities including p47phox, and Nox2 and Nox4 mRNA expression. These changes were linked with activation of PKCα protein and phosphorylation of the extracellular signal-regulated protein kinase (ERK1/2), Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling in ACE2 KO mice. Loss of p47 subunit prevented the increase in NADPH oxidase activity and attenuated the adverse remodeling in the ACE2 KO mice. Conclusions: Loss of ACE2 accelerates pressure-overload induced myocardial oxidative stress, ventricular dysfunction by activation of the NADPH oxidase subunits with the p47 subunit playing a key role. ACE2 suppresses the myocardial NADPH oxidase system possible by reducing Ang II levels.