Endoglin is expressed in the chicken vasculature and is involved in angiogenesis

Endoglin is a component of the transforming growth factor beta (TGF-beta) r eceptor complex, highly expressed by endothelial cells. Mutations in the en doglin gene are responsible for hereditary hemorrhagic telangiectasia type 1 (HHT1), an autosomal dominant vascular disorder caused by a haploinsuffic iency mechanism. Vascular lesions (telangiectasia and arteriovenous malform ations) in HHT1 are associated with loss of the capillary network, suggesti ng the involvement of endoglin in vascular repair processes. Using the chic k chorioallantoic membrane (CAM) as an angiogenic model, we have analyzed t he expression and function of chicken endoglin, A pan-specific polyclonal a ntibody (pAb) recognized chicken endoglin as demonstrated by immunostaining and Western blot analysis. In ovo treatment of chicken embryos with this p Ab resulted in a significantly increased area of CAM. This effect was likel y mediated by modulation of the ligand binding to endoglin as this pAb was able to inhibit TGF-beta 1 binding. These results support the involvement o f endoglin in the angiogenic process. (C) 1999 Federation of European Bioch emical Societies.