Transmembrane protein 117 knockdown protects against angiotensin-II-induced cardiac hypertrophy

Mitochondrial dysfunction plays a critical role in the pathogenesis of pathological cardiac hypertrophy. Transmembrane protein 117 modulate mitochondrial membrane potential that may be involved in the regulation of oxidative stress and mitochondrial function. However, its role in the development of angiotensin II (Ang-II)-induced cardiac hypertrophy is unclear. Cardiac-specific TMEM117-knockout and control mice were subjected to cardiac hypertrophy induced by Ang-II infusion. Small-interfering RNAs against TMEM117 or adenovirus-based plasmids encoding TMEM117 were delivered into left ventricles of mice or incubated with neonatal murine ventricular myocytes (NMVMs) before Ang-II stimulation. We found that TMEM117 was upregulated in hypertrophic hearts and cardiomyocytes and TMEM117 deficiency attenuated Ang-II-induced cardiac hypertrophy in vivo. Consistently, the in vitro data demonstrated that Ang-II-induced cardiomyocyte hypertrophy significantly alleviated by TMEM117 knockdown. Conversely, overexpression of TMEM117 exacerbated cardiac hypertrophy and dysfunction. An Ang II-induced increase in cardiac (cardiomyocyte) oxidative stress was alleviated by cardiac-specific knockout (knockdown) of TMEM117 and was worsened by TMEM117 supplementation (overexpression). In addition, TMEM117 knockout decreased endoplasmic reticulum stress induced by Ang-II, which was reversed by TMEM117 supplementation. Furthermore, TMEM117 deficiency mitigated mitochondrial injury in hypertrophic hearts and cardiomyocyte, which was abolished by TMEM117 supplementation (overexpression). Taken together, these findings suggest that upregulation of TMEM117 contributes to the development of cardiac hypertrophy and the downregulation of TMEM117 may be a new therapeutic strategy for the prevention and treatment of cardiac hypertrophy.