Hsa-miR-497 as a new regulator in TGFβ signaling pathway and cardiac differentiation process.

Cardiosphere-derived cells (CDCs) contain cardiac stem cell subpopulations and are introduced as useful source for cardiac differentiation and therapy. Furthermore, research has highlighted miRNAs important role in various biological processes and cardiogenesis. Here, we intended to investigate the effect of hsa-miR-497 (miR-497) on TGFβ signaling pathway genes expression during the process of CDCs differentiation to cardiomyocytes. CDCs were successfully differentiated to the cardiac-like cells. In this study, we found that after cardiac differentiation induction, miR-497 expression was significantly decreased. Computational miRNA target prediction analyses revealed that TGFβ signaling pathway is a possible target of miR-497. Therefore, miR-497 was overexpressed in CDCs before the induction of differentiation. TGFβ1, TGFβR1, TGFβR2, and SMAD3 genes expression level was decreased after miR-497 overexpression. Also, immunocytochemistry and cell morphology analysis indicated that miR-497 overexpression affecting cardiac differentiation process. Finally, direct interaction of miR-497 with 3'-UTR sequence of TGFβR1 was supported through dual luciferase assay, consistent with miR-497 reported negative effect on SMAD3 expression. Accordingly, here a model of miR-497 involvement in regulation of TGFβ signaling pathway is introduced in which, side branches of TGFβ signaling pathway downregulate miR-497 to ensure upregulation of TGFβR1 and TGFβR2 and finally stronger TGFβ signaling.