Ovine vascular endothelial growth factor: Nucleotide sequence and expression in fetal tissues

To examine the role of vascular endothelial growth factor (VEGF) in mediating angiogenesis and vascular permeability during fetal development, we determined the gene expression of VEGF in ovine fetal tissues. Further, we cloned and sequenced the ovine VEGF cDNA encoding VEGF₁₆₄ from sheep placenta. VEGF protein was localized in epithelial cells of the placenta and fetal kidney, and in hepatocytes of the fetal liver. By Northern analysis, a major VEGF mRNA species of 3.7 kb was identified in all tissues examined, with abundance highest in the lung and lowest in the liver. The most prominent molecular form expressed in ovine fetal tissues appeared to be VEGF₁₆₄ with low levels of expression of VEGF₁₂₀ and VEGF₁₈₈. Cloning and sequence analysis of the most abundant form of ovine VEGF cDNA in the placenta confirmed the prediction of a 164-amino acid peptide, with a putative N-terminal signal sequence of 26 amino acids. Comparison of the VEGF cDNA sequence among different species revealed that VEGF is highly conserved suggesting an important role in development.