Ghrelin Alleviates Angiotensin II-Induced H9c2 Apoptosis: Impact of the miR-208 Family.

BACKGROUND Ghrelin is a novel peptide with abundant cardioprotective effects. The miR-208 family, consisting of cardiac-specifically expressed microRNAs, are not only involved in hypertrophy and fibrosis, but are also closely related with myocyte apoptosis. This study explored the role of the miR-208 family in the protective effect of ghrelin on angiotensin II (Ang II)-induced apoptosis. MATERIAL AND METHODS H9c2 cells were exposed to Ang II with or without ghrelin. Cell viability was detected by MTT assay and the percentage of apoptotic cells was confirmed by flow cytometry. miRNAs expression levels were measured by qRT-PCR. Then, cells transfected with miR-208 negative control, mimics, and inhibitors were treated with Ang II and ghrelin, followed by flow cytometry. PCR array was performed to explore the pathways affected by miR-208. RESULTS The miR-208 level was reduced in Ang II-treated H9c2 cells, accompanied with increased cell apoptosis, which were both reversed by ghrelin administration. Flow cytometry revealed that miR-208 inhibitors clearly upregulated the apoptotic percentage, whereas miR-208 mimics showed the opposite effects in the Ang II group. miR-208a further alleviated apoptosis when treated with ghrelin. miR-208 mainly affected caspase, inflammatory-related genes, and several signaling pathways. CONCLUSIONS We provide new evidence that the miR-208 family is regulated by Ang II and ghrelin. Overexpression of miR-208 family alleviated Ang II-induced cell apoptosis and miR-208a assisted in the protective effect of ghrelin. Several apoptosis pathways affected by miR-208 family were found. These findings suggest the pathogenesis of cardiomyocyte apoptosis and the protective mechanism of ghrelin.