avβ3 Integrin limits the contribution of neuropilin-1 to vascular endothelial growth factor-induced angiogenesis

Both vascular endothelial growth factor receptors (VEGFR) and integrins are major regulators of VEGF-induced angiogenesis. Previous work has shown that ß3 integrin can regulate negatively VEGFR2 expression. Here we show that ß3 integrin can regulate negatively VEGF-mediated angiogenesis by limiting the interaction of the co-receptor NRP1 (neuropilin-1) with VEGFR2. In the presence of avß3 integrin, NRP1 contributed minimally to VEGF-induced angiogenic processes in vivo, ex vivo, and in vitro. Conversely, when ß3 integrin expression is absent or low or its function is blocked with RGD-mimetic inhibitors, VEGF-mediated responses became NRP1-dependent. Indeed, combined inhibition of ß3 integrin and NRP1 decreased VEGF-mediated angiogenic responses further than individual inhibition of these receptors. We also show that avß3 integrin can associate with NRP1 in a VEGF-dependent fashion. Our data suggest that ß3 integrin may, in part, negatively regulate VEGF signaling by sequestering NRP1 and preventing it from interacting with VEGFR2.