Structure‐activity studies of competitive ligand binding to neuropilin in angiogenesis

Neuropilin‐1 is a cell surface receptor with critical roles in angiogenesis and axon guidance. Interestingly, its two ligands, vascular endothelial growth factor‐A (VEGF‐A) and semaphorin‐3f (sema‐3f), have opposite roles in regulating angiogenesis. Indeed, sema‐3f is a potent endogenous angiogenesis inhibitor. We hypothesize that the inhibition of angiogenesis by sema‐3f is mediated by its physical competition with VEGF‐A for neuropilin. Using an in vitro binding assay, we have identified a peptide from the c‐terminal domain of sema‐3F that competes with VEGF‐A for binding to the neuropilin‐1 b1 domain. This peptide also inhibits VEGF‐A dependent VEGFR‐2 phosphorylation in situ . Structural and mutagenesis data demonstrate that a C‐terminal arginine is critical for the binding of this sema‐3f derived peptide to neuropilin. The dimeric nature of sema‐3f is further shown to be essential for its potent anti‐angiogenic effect. Supported by the NIH Grant GM094155 and a Kentucky Opportunity Fellowship.