Tie2

Tie2, encoded by TEK, belongs to the Tie1/Tie2 receptor tyrosine kinase class expressed in developing vascular endothelial cells^[1]. Angiopoietin-1 was identified as a secreted ligand for Tie2 and functions as a primary physiological ligand during embryonic angiogenesis^[2][3]. Mechanistically, Ang1-Tie2 signaling supports vascular maturation and has angiogenic actions distinct from VEGF^[3]. In disease-relevant angiogenesis models, Ang2 acts as a natural antagonist for Tie2, disrupts in vivo angiogenesis, and modulates VEGF-induced postnatal neovascularization with Ang1^[4][5]. Compared with Tie1, Tie2 has ligand-defined angiopoietin signaling, whereas Tie1 can negatively regulate Tie2 surface presentation in angiogenic endothelial cells and cooperatively sustain Tie2 signaling in remodeling stalk cells^[7]. In adult tissues, Tie2 expression and phosphorylation occur in both angiogenic and quiescent vasculature, supporting roles in vascular growth and maintenance^[6]. For experimental applications, VE-PTP inhibition activates Tie2 and stabilizes ocular vessels, making Tie2 activation a practical strategy for vascular leakage and neovascularization models^[8].