Sirt4 deficiency conferred resistance to Ang II-induced cardiac hypertrophy and fibrosis, whereas Sirt4 overexpression aggravated hypertrophy and reduced cardiac function.
Does Sirt4 promote Ang II-induced pathological cardiac hypertrophy and dysfunction?
Sirt4 promotes pathological cardiac hypertrophy and dysfunction by increasing ROS levels through the inhibition of MnSOD activity, identifying it as a potential therapeutic target for heart failure.
AIMS: Oxidative stress contributes to the development of cardiac hypertrophy and heart failure. One of the mitochondrial sirtuins, Sirt4, is highly expressed in the heart, but its function remains unknown. The aim of the present study was to investigate the role of Sirt4 in the pathogenesis of pathological cardiac hypertrophy and the molecular mechanism by which Sirt4 regulates mitochondrial oxidative stress. METHODS AND RESULTS: Male C57BL/6 Sirt4 knockout mice, transgenic (Tg) mice exhibiting cardiac-specific overexpression of Sirt4 (Sirt4-Tg) and their respective controls were treated with angiotensin II (Ang II, 1.1 mg/kg/day). At 4 weeks, hypertrophic growth of cardiomyocytes, fibrosis and cardiac function were analysed. Sirt4 deficiency conferred resistance to Ang II infusion by significantly suppressing hypertrophic growth, and the deposition of fibrosis. In Sirt4-Tg mice, aggravated hypertrophy and reduced cardiac function were observed compared with non-Tg mice following Ang II treatment. Mechanistically, Sirt4 inhibited the binding of manganese superoxide dismutase (MnSOD) to Sirt3, another member of the mitochondrial sirtuins, and increased MnSOD acetylation levels to reduce its activity, resulting in elevated reactive oxygen species (ROS) accumulation upon Ang II stimulation. Furthermore, inhibition of ROS with manganese 5, 10, 15, 20-tetrakis-(4-benzoic acid) porphyrin, a mimetic of SOD, blocked the Sirt4-mediated aggravation of the hypertrophic response in Ang II-treated Sirt4-Tg mice. CONCLUSIONS: Sirt4 promotes hypertrophic growth, the generation of fibrosis and cardiac dysfunction by increasing ROS levels upon pathological stimulation. These findings reveal a role of Sirt4 in pathological cardiac hypertrophy, providing a new potential therapeutic strategy for this disease.
Luo et al. (2016) studied Pathological cardiac hypertrophy. Sirt4 knockout or overexpression vs. Respective controls was evaluated on Hypertrophic growth of cardiomyocytes, fibrosis, and cardiac function. Sirt4 deficiency conferred resistance to Ang II-induced cardiac hypertrophy and fibrosis, whereas Sirt4 overexpression aggravated hypertrophy and reduced cardiac function.