ANGIOGENIC ACTIVITY OF A FUSION PROTEIN OF THE CELL-BINDING DOMAIN OFFIBRONECTIN AND BASIC FIBROBLAST GROWTH-FACTOR

We constructed a fusion protein of the cell-binding domain of human fi bronectin and human basic fibroblast growth factor, and prepared a pol ypeptide with both cell-adhesive activity and growth factor activity. A human gene fragment coding for basic fibroblast growth factor was am plified by the polymerase chain reaction, and introduced into the expr ession vector pTF7520, which encodes the cell-binding domain of human fibronectin. The resulting plasmid encoded a fusion protein in which b asic fibroblast growth factor was added covalently to the C-terminal e nd of the fibronectin fragment. The fusion protein was expressed in Es cherichia coli JM109 cells and purified from the extract by heparin af finity chromatography. The purified fusion protein had cell-adhesive a ctivity toward BALB/c 3T3 cells, and stimulated their DNA synthesis in serum-depleted cultures. The fusion protein gave maximum mitogenic ac tivity at the concentration of 10 nM. The fusion protein adsorbed to c ulture dishes, or added to collagen gels, stimulated the growth of hum an umbilical-vein endothelial cells. The fusion protein stimulated the angiogenesis in chorioallantoic membranes of developing chick embryos .