Adenoviral E4 gene stimulates secretion of pigmental epithelium derived factor (PEDF) that maintains long-term survival of human glomerulus-derived endothelial cells.

Renal glomerular endothelial cells are specialized cells with an important role in physiological filtration and glomerular disease. However, maintenance of human primary endothelial cells requires stimulation with serum and growth factors that often results in modification of the cells properties. Previously, expression of early adenovirus region E4 was shown to help maintaining long-term survival of human endothelial cells in serum free media without addition of growth factors. In the current study, we showed that media conditioned with human epithelial cells stably transfected with Ad E4 region also supported survival of human glomerulus-derived endothelial cells in serum-free media. Mass-spectrometry analysis of the conditioned media identified pigmental epithelium derived factor (PEDF) as a major component of the conditioned media. PEDF expression in 293-E4 cells was validated by RT-PCR, Western blot and ELISA analysis. PEDF expression was detected in mouse glomeruli. Supplementation with recombinant PEDF supported survival of primary endothelial cells and the cells transformed with SV40 large T antigen in serum-free media, and extended the life-span of both cell cultures. PEDF did not inhibit FGF-2 stimulated growth and tubulogenesis of endothelial cells. Thus we demonstrated that adenoviral E4 region stimulated expression and secretion of PEDF by human renal epithelial cells that acted as a survival factor for glomerulus-derived endothelial cells.