The endothelial receptor tyrosine kinase tie-1 is upregulated by hypoxia and vascular endothelial growth factor

The receptor tyrosine kinase tie-1 is essential for angiogenesis where it appears to have a role in vessel maturation, Here we have examined the effects of hypoxia and vascular endothelial growth factor (VEGF) on the level of tie-1 protein expressed in bovine aortic endothelial cells, Both hypoxia (2% O-2) and VEGF were found to increase tie-1 in a time-dependent manner, Hypoxic induction was direct and effects of hypoxia and VEGF were not additive. Experiments with actinomycin D indicate that these activators regulate tie-1 at the transcriptional level. (C) 1998 Federation of European Biochemical Societies.