[Expression profile of microRNAs in the cardiomyocytes derived from mouse embryonic stem cells]

Embryonic stem cells (ESCs), derived from the inner cell mass of blastocysts, are self-renewing and pluripotent cells with the ability to differentiate into all derivatives of three primary germ layers, including cardiomyocytes. Recent studies have revealed that posttranscriptional regulations of lineage specific genes by microRNAs (miRNAs) emerge as a new class of cell fate and lineage determinants of ESCs. However, the miRNAs that control ESC differentiation are still largely unexplored. In the present study, we aimed to identify miRNAs that might be involved in cardiac differentiation of ESCs. Using a hanging drop technique, mouse ESCs (mESCs) were differentiated into cardiomyocytes. We then used the Aligent miRNAs chip (miRbase V16.0) to evaluate miRNA expression levels between the ESC-derived beating area enriched with cardiomyocytes and non-beating area. The expression levels of 19 miRNAs changed over 5-fold between two areas (n = 3, P < 0.05). Among them, 5 miRNAs were upregulated and 14 miRNAs were downregulated in the beating area compared with the non-beating area (P < 0.05). Then quantitative real-time-PCR was used to analyze the miRNAs with the differentiated expression level over 10-fold seen in the Aligent miRNAs chip. miR-196a, miR-196b and miR-467e were confirmed to be significantly lower in the beating area than those in the non-beating area (n = 3, P < 0.05). TargetScan analysis further suggested that miR-196a and miR-196b might be negatively related to the cardiomyocytes differentiation. Our findings provide a new clue for exploring roles of miRNAs in cardiac lineage commitment of mESCs.