Ang1

Angiopoietin-1 (Ang1) is a secreted glycoprotein that belongs to the angiopoietin family and is encoded by the ANGPT1 gene in humans. It is produced by various cell types, including pericytes and smooth muscle cells, and it functions primarily as a ligand for the Tie2 (TEK) receptor tyrosine kinase present on endothelial cells.

Ang1 exerts its effects by binding and activating the Tie2 receptor, triggering downstream signaling pathways such as PI3K-AKT and MAPK. This signaling promotes endothelial cell survival and quiescence, supports vessel maturation and stabilization, and reduces vascular permeability. Ang1 also helps maintain junctional integrity between endothelial cells, in part by modulating VE-cadherin–based cell–cell contacts, and it has anti-inflammatory effects that can limit leukocyte adhesion and vascular leakage.

Physiologically, Ang1 is important during vascular development to ensure proper vessel formation and maturation. In adulthood, it contributes to the maintenance of vascular stability and barrier function. Dysregulation of Ang1 signaling can contribute to pathological vascular leakage, edema, and inflammatory responses in conditions such as sepsis, diabetic retinopathy, and tumor angiogenesis. Ang2, another angiopoietin family member, can antagonize Ang1 activity under certain conditions, tipping balance toward vessel remodeling or destabilization.

Research and therapeutic approaches have explored Ang1-based strategies to promote vascular stability and reduce leakage, as well as strategies targeting the broader Ang/Tie2 axis. Overall, Ang1 plays a central role in coordinating endothelial cell survival, vessel maturation, and barrier function within the vascular system.