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J.D. Paauw, P.C. Kothary, S.A. Shah, M.A. Del Monte; pERK1,2 Expression Is Required for Platelet–Derived Growth Factor–Induced Mitogenesis in Human Retinal Pigment Epithelial Cells . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5583.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the role of phosphorylated extracellular signal–regulated kinases 1 and 2 (pERK1,2), one of the mitogen activated protein (MAP) kinases, in Platelet Derived Growth Factor (PDGF)–induced human Retinal Pigment Epithelial (hRPE) cell proliferation, and to examine the effects of PD 98059 as a potential inhibitor of pERK1,2 and hRPE proliferation. Methods: Proliferation of hRPE cells in the presence of increasing concentrations of PDGF was measured by trypan blue exclusion, and by measuring 3H–Thymidine incorporation into DNA. pERK1,2 levels were measured by immunoprecipitating 14C–Methionine–labeled pERK1,2 in the presence and absence of PDGF and PD 98509. Immunohistochemistry for pERK1,2 was done using anti–pERK1,2 antibody with control hRPE cells, cells exposed to PDGF (100 pg/ml), and cells exposed to PDGF + PD 98509. Results: PDGF stimulated hRPE cell proliferation in a dose dependent manner and PD 98509 (50 µM) inhibited PDGF (100pg/ml) stimulated proliferation (138,700±13,800 vs. 310,600±33,900 cells/ml±SEM; n=8, p<0.05). Further, PDGF (100 pg/ml) stimulated DNA synthesis as measured by 3H–Thymidine incorporation (840±172 vs. 631±159 CPM±SEM; n=8, p<0.05). PD 98509 also inhibited PDGF (100 pg/ml) stimulated DNA synthesis as measured by 3H–Thymidine (4,564±353 vs. 6,936±765 CPM±SEM; n=8, p<0.05). PDGF (100pg/ml) stimulated pERK1,2 when compared to control (1,462±362 vs. 421±78 CPM±SEM; n=12, p<0.05), and this stimulation was significantly inhibited in the presence of PD 98509 (380±139 CPM±SEM; n=12, p<0.05). Immunohistochemistry demonstrated more pERK1,2 staining in cells exposed to PDGF than control, and cells exposed to PDGF + PD 98509 showed similar staining to control. Conclusions: pERK1,2 mediates PDGF–stimulated hRPE cell proliferation, and its production and activity can be significantly inhibited by PD 98509. Since hRPE cell proliferation is implicated in proliferative eye disease, PD 98509 may be of therapeutic value.
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