MicroRNA‐124 regulates transforming growth factor β1‐induced epithelial‐mesenchymal transition in the retinal pigment epithelium by Down‐regulating expression of the RhoG

Abstract

PurposeMicroRNA‐124 (miR‐124) is thought to be involved in the epithelial‐mesenchymal transition (EMT) of retinal pigment epithelium (RPE). In the present study, we investigated the regulation of miR‐124 on EMT induced by transforming growth factor β1 (TGF‐β1) in human RPE cells (APRE‐19).MethodsThe expression of miR‐124 was evaluated after treatment of TGF‐β1 by quantitative RT‐PCR. Phenotypic alterations were analyzed by western blot analysis and immunocytochemical staining. Target validation was performed to identify the putative target of miR‐124 by luciferase reporter assay.ResultsThe expression level of microRNA‐124 (miR‐124) was down‐regulated during the progression of EMT. Overexpression of miR‐124 upregulated the levels of zonular occludens 1 and RPE65, and down‐regulated fibronectin, α‐smooth muscle actin, and vimentin. Furthermore, inhibition of endogenous miR‐124 increased and decreased the levels of mesenchymal and epithelial factors, respectively. TargetScan predicted two well‐conserved and two vertebrate‐only conserved miR‐124 target sequences in the 3′ untranslated region (UTR) of the RHOG mRNA. Direct targeting of this 3′ UTR by miR‐124 was demonstrated using a luciferase assay. Silencing of RHOG using a specific siRNA had identical effects on EMT regulation. Overexpression of miR‐124 repressed TGF‐β1‐induced RPE cell‐collagen gel lattice contraction by altering cell spreading/cell‐to‐cell adhesion.ConclusionsThis study describes the regulation of EMT in RPE cells by TGF‐β1/miR‐124/RHOG signaling and suggests that the supplement of miR‐124 expression would be a crucial therapeutic target for the prevention or treatment of proliferative vitreoretinopathy.