Regulation of Ras homolog family member G by microRNA-124 regulates proliferation and migration of human retinal pigment epithelial cells

Uncontrolled retinal pigment epithelial (RPE) cell proliferation/migration contribute to the pathological tractional membrane development in proliferative vitreoretinopathy. Recent studies reported that microRNA (miR)-124 controls various cellular functions via the direct targeting of small Ras homolog family member G (RHOG). Therefore, we investigated the role of the neuron-specific miR-124 and RHOG in RPE cell proliferation/migration. Alterations in miR-124 and RhoG expression, as per cell confluence were evaluated through quantitative real-time PCR and western blotting, respectively. After transfection with miR-124, we quantified RPE cell viability and migration and observed cell polarization and lamellipodia protrusions. We evaluated the expression of RHOG/RAC1 pathway molecules in miR-124-transfected RPE cells. Endogenous miR-124 expression increased proportionally to RPE cell density, but decreased after 100% confluence. Overexpression of miR-124 decreased cell viability and migration, BrdU incorporation, and Ki-67 expression. Inhibition of endogenous miR-124 expression promoted RPE cell migration. Transfection with miR-124 reduced cell polarization, lamellipodia protrusion, and RHOG mRNA 3 ' untranslated region luciferase activity. Like miR-124 overexpression, RhoG knockdown decreased RPE cell viability, wound healing, and migration, and altered the expression of cell cycle regulators. These results suggest that miR-124 could be a therapeutic target to alleviate fibrovascular proliferation in retinal diseases by regulating RPE proliferation/migration via RHOG.