MiR-184 directly targets Wnt3 in cardiac mesoderm differentiation of embryonic stem cells.

Embryonic stem (ES) cells have the property of self-renewal and multi-directional differentiation, and provide an ideal model for studying early embryo development in vitro. Wnt3, as Wnt family member 3, plays a vital role during ES cell differentiation. However, the exact regulatory mechanism of Wnt3 remains to be elucidated. MicroRNAs can directly regulate gene expression at the post-transcriptional level and play critical function in cell fate determination. Here, we found the expression level of miR-184 decreased when ES cells differentiated into cardiac mesoderm then increased during the process as differentiated into cardiomyocytes, which negatively correlated with the expression ofWnt3. Overexpression of miR-184 during the process of ES cell differentiation into cardiac mesoderm repressed cardiac mesoderm differentiation and cardiomyocyte formation. Bioinformatics prediction and mechanism studies showed that miR-184 directly bound to the 3 ' UTR region ofWnt3and inhibited the expression level ofWnt3. Consistently, knockdown ofWnt3mimicked the effects of miR-184-overexpression on ES cell differentiation into cardiac mesoderm, whereas overexpression ofWnt3rescued the inhibition effects of miR-184 overexpression on ES cell differentiation. These findings demonstrated that miR-184 is a direct regulator ofWnt3during the differentiation process of ES cells, further enriched the epigenetic regulatory network of ES cell differentiation into cardiac mesoderm and cardiomyocytes.