Genomic structure and alternative splicing of chicken angiopoietin-2

Angiopoietin-1 (Ang-l) prevents endothelial cell apoptosis and promotes blo od vessel stability, while angiopoietin-2 (Ang-a), a natural antagonist of Ang-l, disrupts blood vessel structure and induces apoptosis. We have seque nced the chicken angiopoietin-2 gene that spans about 46 kb of DNA and is s plit in 9 exons by 8 introns. Alternative splicing of the gene gives rise t o three different species of Ang-2 mRNAs: Ang-2A Ang-2B, and Ang-2C. The th ree mRNA isoforms, also present in humans, codify for proteins with an iden tical fibrinogen-like C-terminal domain and a different coiled-coil N-termi nal domain. Ang-2A and particularly Ang-2C are expressed in immature testis and regressed adult testis undergoing vascular remodeling, while their exp ression is barely detectable in quiescent adult testis. Conversely, Ang-2B is only detectable in adult testis. The new isoforms with truncated amino-t erminal domains may modulate the Tie2 receptor during vascular angiogenesis and regression, (C) 2000 Academic Press.