A RECOMBINANT MUTANT VASCULAR ENDOTHELIAL GROWTH FACTOR-C THAT HAS LOST VASCULAR ENDOTHELIAL GROWTH-FACTOR RECEPTOR-2 BINDING, ACTIVATION, AND VASCULAR-PERMEABILITY ACTIVITIES

The vascular endothelial growth factor (VEGF) and the VEGF-C promote g rowth of blood vessels and lymphatic vessels, respectively, VEGF activ ates the endothelial VEGF receptors (VEGFR) 1 and 2, and VEGF-C activa tes VEGFR-3 and VEGFR-2. Both VEGF and VEGF-C are also potent vascular permeability factors. Here we have analyzed the receptor binding and activating properties of several cysteine mutants of VEGF-C including those (Cys(156) and Cys(165)), which in other platelet-derived growth factor/VEGF family members mediate interchain disulfide bonding, Surpr isingly, we found that the recombinant mature VEGF-C in which Cys(156) was replaced by a Ser residue is a selective agonist of VEGFR-3. This mutant, designated Delta N Delta C156S, binds and activates VEGFR-3 b ut neither binds VEGFR-2 nor activates its autophosphorylation or down stream signaling to the ERK/MAPK pathway. Unlike VEGF-C, Delta N Delta C156S neither induces vascular permeability in vivo nor stimulates mi gration of bovine capillary endothelial cells in culture. These data p oint out the critical role of VEGFR-2-mediated signal transduction for the vascular permeability activity of VEGF-C and strongly suggest tha t the redundant biological effects of VEGF and VEGF-C depend on bindin g and activation of VEGFR-2. The Delta N Delta C156S mutant may provid e a valuable tool for the analysis of VEGF-C effects mediated selectiv ely via VEGFR-3. The ability of Delta N Delta C156S to form homodimers also emphasizes differences in the structural requirements for VEGF a nd VEGF-C dimerization.