MicroRNA-29b regulates TGF-β1-mediated epithelial-mesenchymal transition of retinal pigment epithelial cells by targeting AKT2.

The role of microRNA (miRNA) in proliferative vitreoretinopathy (PVR) progression has not been studied extensively, especially in retinal pigment epithelial-mesenchymal transition (EMT) which is the main reason for formation of PVR. In this study, we first investigated the miRNA expression profile in transforming growth factor beta 1 (TGF-β1) mediated EMT of ARPE-19 cells. Among the five changed miRNAs, miR-29b showed the most significant downregulation. Enhanced expression of miR-29b could reverse TGF-β1 induced EMT through targeting Akt2. Akt2 downregulation could inhibit TGF-β1-induced EMT. Furthermore, inhibition of miR-29b in ARPE-19 cells directly triggered EMT process, which characterized by the phenotypic transition and the upregulation of α-smooth muscle actin (α-SMA) and downregulation of E-cadherin and zona occludin-1 (ZO-1) with increased cell migration. Akt2-shRNA also inhibited miR-29 inhibitor-induced EMT process. These data indicate that miR-29b plays an important role in TGF-β1-mediated EMT in ARPE-19 cells by targeting Akt2.