Loss of miR-424 and miR-503 promotes decidualization of human endometrial stromal cells by increasing SCARA5 expression

This study aims to investigate the function of miR-424 and miR-503, identified as putative regulatory miRNAs of FOXO1, a key factor for decidualization. The expression of both miR-424 and miR-503 in human endometrial stromal cells (HESCs) were measured before and after decidualization. Then, HESCs were transfected with both miR-424 and miR-503 before decidualization. Quantitative reverse transcription PCR, actin staining analysis, migration assay, fluorescence immunostaining, and luciferase assay were performed. MiR-424 and miR-503 expression was decreased after decidualization. Overexpression of both miR-424 and miR-503 inhibited major decidual maker genes, including FOXO1, PRL, IGFBP1, WNT4, and SCARA5, and altered F-actin's subcellular distribution from the periphery to all over the cytoplasm, concomitantly increasing cell mobility. Moreover, immunohistochemical analysis revealed overexpression of both miRNAs resulted in FOXO1 protein accumulation in the cytoplasm. Knocking down FOXO1 decreased SCARA5 expression, revealing SCARA5 is a downstream target of FOXO1. In addition, a luciferase reporter assay confirmed that the 3'-untranslated region of FOXO1 mRNA is targeted by miR-424. These results suggest that both miRNAs may play an important role in endometrial decidualization by regulating transcriptional activity of FOXO1, which alters decidualization-related gene expression such as SCARA5.Abstract: Journal standard instruction requires an unstructured abstract; hence structured abstract changed to unstructured.Thank you for the correction. I approve this change.