Tie

Angiopoietins (Angs) are important vascular growth factors that regulate vascular remodeling, maturation, and stabilization. Angs also regulate vascular reactivity through regulating the production of nitric oxide (NO). The Angs family includes Ang1, Ang2, and Ang4 (a human orthologue of mouse Ang3) which interacts with tyrosine kinase receptors (Tie1 and Tie2). The angiopoietins receptors Tie1 and Tie2 (also known as TEK) are almost exclusively expressed in the endothelium, but there is some expression also in haematopoietic cells. The growth factors Ang1, Ang2 and Ang4 (the human orthologue of mouse Ang3) are ligands for Tie2, whereas Tie1 is an orphan receptor that can nevertheless be activated by angiopoietins via its interaction with Tie2. Ang-Tie signaling is involved in various processes of vascular development and remodeling in different diseases.