Epidermal growth factor: the driving force in initiation of RPE cell proliferation

To analyze whether epidermal growth factor (EGF) exerts regulatory effects on proliferation and differentiation in ARPE19 cells after different incubation periods (24 vs. 48 h) for obtaining ideal conditions for feasible rejuvenation and autologous transplantation of retinal pigment epithelial cells (RPE cells). To evaluate gene expression patterns of RPE-specific differentiation and proliferation markers as well as transcriptional and translational changes of beta-catenin (-catenin)-signaling markers by fluorescence activated cell sorting (FACS) and reverse transcription - polymerase chain reaction (RT-PCR) after 24 h of EGF treatment. After 24 h of EGF treatment, a significant decrease of retinal pigment epithelium-specific protein 65 (RPE 65), cellular retinaldehyde-binding protein (CRALBP) and cytokeratin 18 in ARPE-19 cells was scaled. In addition, an increase of cyclin D1 expression and a significant decrease of glycogen synthase kinase-3beta (GSK-3) and beta-catenin (-catenin) were equally observed after 24 and 48 h of EGF treatment. Cell-cycle studies revealed an increase of ARPE cells in S-G2/M phase after 24 h of EGF treatment. Our data demonstrate the induction of proliferation and upregulation of the -catenin signaling pathway by EGF even after 24 h of incubation. As ideal cell culture conditions are essential for maintaining RPE-specific phenotypes, short incubation times enhance RPE cell quality for feasible rejuvenation and subsequent autologous transplantation of RPE cells.