VEGF162, A New Heparin-binding Vascular Endothelial Growth Factor Splice Form That Is Expressed in Transformed Human Cells

The splice forms of vascular endothelial growth factor (VEGF) differ in biological properties such as the receptor types that they recognize and their interaction with heparan sulfate proteoglycans. We have identified a new VEGF mRNA splice form encoding a VEGF species containing 162 amino acids (VEGF162) in human A431 ovarian carcinoma cells. This novel mRNA contains the peptides encoded by exons 1-5, 6A, 6B, and 8 of the VEGF gene. Recombinant VEGF162 is biologically active. It induces proliferation of endothelial cells in vitro and angiogenesis in vivo as determined by the alginate bead assay. VEGF162 binds less efficiently than VEGF145 but more efficiently than VEGF165 to a natural basement membrane produced by corneal endothelial cells. VEGF138, an artificial VEGF form that contains exon 6B but lacks exons 6A and 7, did not bind to this basement membrane at all, indicating that exon 6B probably interferes with the interaction of exon 6A with heparin and heparan sulfate proteoglycans.