Downregulation of MicroRNA-494 inhibits the TGF-β1/Smads signaling pathway and prevents the development of hypospadias through upregulating Nedd4L

Background: Hypospadias, as a congenital disorder of the urethra, is the second most common birth abnormally of the male reproductive system. This study primarily investigates the effects of microRNA-494 (miR-494) on the transforming growth factor-beta 1 (TGF-beta 1)/Smads signaling pathway and on the development of hypospadias by binding to neural precursor cell expressed developmentally downregulated gene 4-like (Nedd4L). Methods: We induced a mouse model of hypospadias through di-(2-ethylhexyl) phthalate treatment. The underlying regulatory mechanisms of miR-494 in this model were analyzed upon treatment of miR-494 mimic, miR-494 inhibitor, or small interfering RNA against Nedd4L in urethral epithelial cells isolated from mice with hypospadias. We then verified the binding site between miR-494 and Nedd4L and applied a gain- and loss-of-function approach to determine the effects of miR-494 on cell proliferation, cycle distribution, and apoptosis. Results: Male mice with hypospadias exhibited significantly higher miR-494 expression and lower Nedd4L expression in urethral tissues than normal male mice. Nedd4L was verified as a target gene of miR-494. Treatment with miR-494 inhibitor suppressed the activation of the TGF-beta 1/Smads signaling pathway, whereas downregulation of miR-494 exerted protective effects on urethral epithelial cells by impeding cell proliferation and inducing cell apoptosis. Conclusions: The study indicates that downregulation of miR-494 inhibits the TGF-beta 1/Smads signaling pathway and prevents the development of hypospadias through upregulating Nedd4L.