MiR-181a mediates Ang II-induced myocardial hypertrophy by mediating autophagy.

OBJECTIVE: To investigate the relationship between miR-181a and cardiac hypertrophy and autophagy in rats with myocardial hypertrophy, and whether miR-181a regulates the autophagy through ATG5, thereby participating in the occurrence and development of myocardial hypertrophy.

MATERIALS AND METHODS: The rat model of myocardial hypertrophy was established via the abdominal aortic coarctation. The expression of miR-181a in cardiac tissues was detected via reverse transcription-polymerase chain reaction (RT-PCR). The expressions of autophagy-related proteins, ATG5 and LC3II/LC3I, in cardiac tissues, were detected via Western blotting (WB). After the primary culture of myocardial cells in rats, they were stimulated via Angiotensin II (Ang II) to observe the effects of autophagy inhibitor 3-methyladenine (3-MA) and overexpression of ATG5 on the expression of hypertrophic genes in myocardial cells, respectively. The expressions of autophagy-related proteins ATG5 and LC3II/LC3I were detected via WB, the autophagic rate was observed via flow cytometry and the changes in autophagic vacuoles of myocardial cells were observed using the transmission electron microscope. The changes in mRNA and protein expressions of ATG in myocardial cells were observed after the overexpression of miR-181a or the inhibition of miR-181a activity. The changes in miR-181a and the expression of hypertrophic genes in myocardial cells after Ang II stimulation were observed via RT-PCR.

RESULTS: In rats with myocardial hypertrophy, the cardiac autophagy was increased and the expression of miR-181a in hypertrophic myocardium was downregulated. 3-MA inhibited the ATG5-induced autophagy and improved the Ang II-induced myocardial hypertrophy, while the overexpression of ATG5 enhanced the myocardial autophagy and the expression of hypertrophic genes. MiR-181a regulated the ATG5-induced myocardial autophagy, and its downregulation mediated the Ang II-induced myocardial hypertrophy.

CONCLUSIONS: The enhancement of ATG5-induced myocardial autophagy mediates the Ang II-induced myocardial hypertrophy. ATG5 is the target gene of miR-181a, it can regulate the myocardial autophagy via ATG5, thus mediating the Ang II-induced myocardial hypertrophy.