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 of Wnt3. 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 of Wnt3 and inhibited the expression level of Wnt3. Consistently, knockdown of Wnt3 mimicked the effects of miR‐184‐overexpression on ES cell differentiation into cardiac mesoderm, whereas overexpression of Wnt3 rescued the inhibition effects of miR‐184 overexpression on ES cell differentiation. These findings demonstrated that miR‐184 is a direct regulator of Wnt3 during the differentiation process of ES cells, further enriched the epigenetic regulatory network of ES cell differentiation into cardiac mesoderm and cardiomyocytes. MiR‐184 is critical for the differentiation of ES cells by directly targeting Wnt3, thereby inhibits the differentiation of ES cells into cardiac mesoderm, and finally affects the differentiation of cardiac mesoderm into cardiomyocytes. These findings not only elucidated the mechanism of endogenous regulation of Wnt3 by miR‐184, but also enriched the epigenetic regulatory network of ES cell differentiation.