Unique signal transduction of the VEGF family members VEGF-A and VEGF-E.

Both VEGF (vascular endothelial growth factor)-A and Orf-virus-encoded VEGF-E bind and activate VEGFR (VEGF receptor)-2; however, only VEGF-A binds VEGFR-1. To understand the biological differences between VEGF-A and VEGF-E in vivo, we established transgenic mouse models. K14 (keratin-14)-promoter-driven VEGF-E transgenic mice showed a significant increase in mature blood vessels. However, K14-VEGF-A transgenic mice exhibited severe inflammation and oedema with increased angiogenesis, as well as lymphangiogenesis and lymph vessel dilatation. K14-VEGF-A transgenic mice deficient in VEGFR-1 signalling (K14-VEGF-A-tg/VEGFR-1 TK(-/-) mice) showed decreases in oedema and inflammation with less recruitment of macrophage-lineage cells, suggesting an involvement of VEGFR-1 in these adverse effects. VEGFE might be more useful than VEGFA for pro-angiogenic therapy.