RETINAL-PIGMENT EPITHELIAL-CELLS SECRETE AND RESPOND TO HEPATOCYTE GROWTH-FACTOR

Hepatocyte growth factor (HGF) is normally expressed by mesenchymal ce lls while its receptor, c-Met, is expressed in epithelial cells. Since HGF is critically involved in epithelial-mesenchyme interactions and the retinal pigment epithelium (RPE) is present at the interface betwe en the retina and choroid, this study was initiated to determine wheth er the RPE expresses or responds to HGF in vitro. Cultured adult and f etal human RPE expressed mRNA for HGF and c-Met by RT-PCR. ELISA assay demonstrated the secretion of HGF into RPE culture supernatants. Tyro sine phosphorylation of c-Met was constitutively found in 72 hour RPE cultures and could be rapidly induced in serum-starved cells by concen trated RPE supernatants. HGF was mitogenic for cultured RPE (100 ng/ml ,) and stimulated their chemotaxis (maximal response at 50 ng/ml). RPE are one of only a very limited number of epithelia that express both HGF and its receptor, suggesting the possibility of an autocrine actio n for this growth factor. (C) 1998 Academic Press.