Functional Role and Mechanism of microRNA-28b in Atrial Myocyte in a Persistent Atrial Fibrillation Rat Model

BACKGROUND Persistent atrial fibrillation has been indicated to be related with microRNA-28b. However, the exact role of microRNA-28b in persistent atrial fibrillation needs to be further elucidated. Therefore, this study aimed to establish a rat model of persistent atrial fibrillation to investigate the level of microRNA-28b in atrial myocytes and to explore the molecular mechanism involved. MATERIAL AND METHODS A persistent atrial fibrillation model was established in rats by using chronic rapid atrial pacing induction. The size of the heart was measured by ultrasonic method. The expression of microRNA-28b in left atrial myocytes was quantified by RT-PCR. Cardiomyocytes were isolated and cultured to detect cell proliferation and apoptosis by MTT and flow cytometry, respectively. The specific inhibitor of ERK signaling pathway, PD98059, was used to further illustrate the role of ERK signaling pathway in the modulation of cardiomyocytes in persistent atrial fibrillation. RESULTS MicroRNA-28b was up-regulated in the experimental rat model with persistent atrial fibrillation. The proliferation of cardiomyocytes was significantly inhibited with potentiated apoptosis. Blockage of the ERK pathway suppressed the microRNA-28b expression and inhibited cell apoptosis. CONCLUSIONS microRNA-28b-induced growth inhibition and cell apoptosis of atrial myocytes was observed in the rat model with persistent atrial fibrillation, via activation of the ERK signaling pathway.