Rap1GAP Mediates Angiotensin II-Induced Cardiomyocyte Hypertrophy by Inhibiting Autophagy and Increasing Oxidative Stress

Abnormal autophagy and oxidative stress contribute to angiotensin II- (Ang II-) induced cardiac hypertrophy and heart failure. We previously showed that Ang II increased Rap1GAP gene expression in cardiomyocytes associated with hypertrophy and autophagy disorders. Using real-time PCR and Western blot, we found that Rap1GAP expression was increased in the heart of Sprague Dawley (SD) rats infused by Ang II compared with saline infusion and in Ang II vs. vehicle-treated rat neonatal cardiomyocytes. Overexpression of Rap1GAP in cultured cardiomyocytes exacerbated Ang II-induced cardiomyocyte hypertrophy, reactive oxygen species (ROS) generation, and cell apoptosis and inhibited autophagy. The increased oxidative stress caused by Rap1GAP overexpression was inhibited by the treatment of autophagy agonists. Knockdown of Rap1GAP by siRNA markedly attenuated Ang II-induced cardiomyocyte hypertrophy and oxidative stress and enhanced autophagy. The AMPK/AKT/mTOR signaling pathway was inhibited by overexpression of Rap1GAP and activated by the knockdown of Rap1GAP. These results show that Rap1GAP-mediated pathway might be a new mechanism of Ang II-induced cardiomyocyte hypertrophy, which could be a potential target for the future treatment of cardiac hypertrophy and heart failure.