Abstract
Purpose: :
We have reported earlier that ARPE–19 cells, a cell line derived from human retinal pigment epithelial (RPE) cells, were differentiated into neuronal phenotype by treatment with the synthetic retinoid fenretinide (4HPR). The purpose of this study was to investigate the role of proteins involved in cell signal transduction, cell cycle check point, and cell differentiation in the neuronal differentiation of ARPE–19 cells by fenretinide.
Methods: :
ARPE–19 cells in culture were treated with 1.0 µM fenretinide. Cells were analyzed by immunocytochemistry and western blotting using antibodies against pax–6, neuronal specific enolase (NSE), map–II, tubulin ß–III, 14–3–3 and bag–1 proteins.
Results: :
We found that pax–6 and NSE were both expressed in the control ARPE–19 cells. Fenretinide induced neuronal differentiation of ARPE–19 cells led to a decrease in pax–6 protein expression and an increase in tubulin ß–III and map–II protein expression after 5 days of fenretinide treatment. There was an increase in nuclear expression and a decrease in cytosol expression of 14–3–3, and an increase in nuclear expression of bag–1 after treatment.
Conclusions: :
The fenretinide induced neuronal differentiation of ARPE–19 cells is associated with an increase in expression of the neuronal specific proteins tubulin ß–III and map–II, and a decrease in expression of the progenitor cell marker pax–6. Neuronal differentiation of ARPE–19 cells is also associated with nuclear translocation of 14–3–3, a protein involved in signal transduction, cell cycle check point and cell growth, and an increase in expression of bag–1, a protein involved in neuronal cell survival and axon elongation. These results suggest that ARPE–19 cells could be a progenitor cell line that can be differentiated into neuronal cells when treated with factors such as fenretinide.
Keywords: retinal culture • retinal development • retinal pigment epithelium