Angiogenesis of capillary endothelial cells includes at least four sequential cellular responses: digestion of basement membrane, migration, proliferation, and differentiation. To study differentiation of endothelial cells, we established a brain capillary endothelial cell line from H-2Kb-tsA58 transgenic mice. These cells are stable at 33 degrees C and display endothelial cell-specific characters, such as expression of von Willebrand factor and binding sites for the lectin Bandeiraea simplifolia, and uptake of acetylated-low density lipoprotein. We measured the effects of a panel of growth factors on cellular responses. A number of factors, such as hepatocyte growth factor, vascular endothelial growth factor, and platelet-derived growth factor (PDGF)-AA failed to induce biological responses. PDGF-BB, epidermal growth factor, and acidic and basic fibroblast growth factor (FGF) induced proliferation of the cells. Of all the factors tested, only acidic FGF and basic FGF induced differentiation of the cells, visualized as the formation of tube-like structures of cells grown in three-dimensional collagen gels. All factors were also analyzed for their effects on plasminogen activator (PA)-induction and migration of the cells. Transfected cells, expressing a chimeric receptor, composed of the extracellular part from the PDGF alpha-receptor and the intracellular part from FGF receptor-1, responded to PDGF-AA treatment with plasminogen activator induction, migration, proliferation, and tube formation in collagen. These results indicate that FGF receptor-1 coupled to signal transduction pathways, leading to differentiation. This novel cell model offers the potential of detailed dissection of signal transduction pathways involved in the differentiation of endothelial cells.