Platelet-Derived Growth Factor Up-Regulates Cell-Mediated Type I Collagen Gel Contraction and Integrin Alpha 2 mRNA Expression via Mitogen-Activated Protein Kinase (MAPK) Pathway in a Retinal Pigment Epithelial (RPE) Cell Line

Abstract

Abstract: : Purpose:Retinal pigment epithelial (RPE) cell and its contraction of extracellular matrix (ECM) are believed to contribute toward developing proliferative vitreoretinopathy (PVR). It has been shown that platelet-derived growth factor (PDGF) and integrin α2 are mainly involved in this process. In order to study how these two are related, we investigated if mitogen-activated protein kinase (MAPK) pathway is involved. Methods:PDGF-activated contractile activity of SV-40 transformed human RPE cell line was evaluated using type I collagen gel contraction assay and the effect of mitogen-activated protein kinase (MAPK) inhibitor, PD98059 on contraction was investigated. Similarly, the effect of PD98059 on integrin α2 mRNA expression in response to PDGF was investigated using reverse transcription polymerase chain reaction (RT-PCR). The effect of PD98059 on MAPK phosphorylation was confirmed by Western blot analysis. Results:PDGF treatment up-regulated both collagen gel contraction and α2 integrin mRNA expression. Pretreatment of cells with PD98059 inhibited these effects in a dose dependent manner. MAPK phosphorylation was inhibited in the presence of PD98059. Conclusions:PDGF up-regulates type I collagen gel contraction and integrin α2 mRNA expression via MAPK pathway in RPE cells, indicating that MAPK and its downstream pathway may be the main contributor in developing PVR.

Keywords: growth factors/growth factor receptors • proliferative vitreoretinopathy • signal transduction