Purchase this article with an account.
M. Hollborn, A. Bringmann, P. Wiedemann, L. Kohen; PDGF Stimulates VEGF Production by Human Retinal Pigment Epithelial Cells . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5531.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Both platelet–derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) have been implicated in the development of proliferative retinopathies. To examine whether PDGF may directly stimulate the expression of VEGF by retinal pigment epithelial (RPE) cells, we investigated the regulation of the gene and protein expression of VEGF by PDGF in human RPE cells in vitro, and determined the involvement of three signal transduction pathways.
Cultured human RPE cells of passages 3 – 5 were used. mRNA expression was analyzed by real–time PCR. Cell proliferation was evaluated by a bromodeoxyuridine immunoassay, chemotaxis was investigated by a Boyden chamber assay, and secretion of VEGF was determined by ELISA. The phosphorylation levels of ERK1/2, p38, and Akt were investigated by Western blotting. Selective pharmacological blockers were used to determine the involvement of the three signaling cascades in PDGF–dependent cellular responses.
PDGF stimulated the gene and protein expression of VEGF–A by human RPE cells, and increased cell proliferation and chemotaxis. PDGF activated all three signaling pathways investigated in RPE cells, as determined by increased phosphorylation levels of ERK1/2, p38, and Akt proteins. The three signaling pathways were involved in the mediation of PDGF–evoked cell proliferation, while p38 and PI3K mediated cell migration, and PI3K mediated secretion of VEGF–A. In addition to VEGF–A, the cells expressed mRNAs for various members of the VEGF family and for their receptors, including VEGF–B, –C, –D, flt–1, and KDR. From these molecules only the VEGF–A mRNA amount was upregulated by PDGF.
The results indicate that PDGF selectively stimulates the expression of VEGF–A in RPE cells. PDGF evokes at least three signal transduction pathways which are differentially involved in various cellular responses, i.e., cell proliferation and migration, and production of VEGF.
This PDF is available to Subscribers Only