Distinct heparin binding sites on VEGF165 and its receptors revealed by their interaction with a non sulfated glycoaminoglycan (NaPaC)

We previously demonstrated that a non sulfated analogue of heparin, phenylacetate carboxymethyl benzylamide dextran (NaPaC) inhibited angiogenesis. Here, we observed that NaPaC inhibited the VEGF165 binding to both VEGFR2 and NRP-1 and abolished VEGFR2 activity. Further, we explored the effects of NaPaC on VEGF165 interactions with its receptors, VEGFR2 and NRP-1, co-receptor of VEGFR2. Surface plasmon resonance and affinity gel electrophoresis showed that NaPaC interacted directly with VEGF165, VEGFR2 and NRP-1 but not with heparin-independent factor such as VEGF121. NaPaC completely inhibited the heparin binding to VEGF165, NRP-1 and VEGFR2. We found that NaPaC bound to all three molecules, VEGF165, VEGFR2 and NRP-1, but was more effective in inhibiting heparin binding to VEGF165. These results suggested that heparin binding sites of VEGFR2 and NRP-1 were different from those of VEGF165.