Abnormal blood vessel development and lethality in embryos lacking a single VEGF allele

P Carmeliet, V Ferreira, G Breier, S Pollefeyt… - Nature, 1996 - nature.com
P Carmeliet, V Ferreira, G Breier, S Pollefeyt, L Kieckens, M Gertsenstein, M Fahrig…
Nature, 1996nature.com
THE endothelial cell-specific vascular endothelial growth factor (VEGF) 1–5 and its cellular
receptors Flt-1 (refs 6, 7) and Flk-1 (refs 8, 9) have been implicated in the formation of the
embryonic vasculature. This is suggested by their colocalized expression during
embryogenesis10, 11 and the impaired vessel formation in Flk-1 (ref. 12) and Flt-1 (ref. 13)
deficient embryos. However, because Flt-1 also binds placental growth factor14, 15, a VEGF
homologue, the precise role of VEGF was unknown. Here we report that formation of blood …
Abstract
THE endothelial cell-specific vascular endothelial growth factor (VEGF)1–5 and its cellular receptors Flt-1 (refs 6,7) and Flk-1 (refs 8,9) have been implicated in the formation of the embryonic vasculature. This is suggested by their colocalized expression during embryogenesis10,11 and the impaired vessel formation in Flk-1 (ref. 12) and Flt-1 (ref. 13) deficient embryos. However, because Flt-1 also binds placental growth factor14,15, a VEGF homologue, the precise role of VEGF was unknown. Here we report that formation of blood vessels was abnormal, but not abolished, in heterozygous VEGF-deficient (VEGF+/-) embryos, generated by aggregation of embryonic stem (ES) cells with tetraploid embryos (T-ES)16,17, and even more impaired in homozygous VEGF-deficient (VEGF-/-) T-ES embryos, resulting in death at mid-gestation. Similar phenotypes were observed in F1-VEGF-/- embryos, generated by germline transmission. We believe that this heterozygous lethal phenotype, which differs from the homozygous lethality in VEGF-receptor-deficient embryos, is unprecedented for a targeted autosomal gene inacti-vation, and is indicative of a tight dose-dependent regulation of embryonic vessel development by VEGF.
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