Angiopoietin 2 Is a Partial Agonist/Antagonist of Tie2 Signaling in the Endothelium

Volume 29, no. 8, p. 2011-2022, 2009. After publication, we identified an article describing Ang-2 as a weaker activator of Tie-2 than Ang-1 (E. Bogdanovic, V. P. Nguyen, and D. J. Dumont, J. Cell Sci. 119:3551-3560, 2006), leading those authors to propose that Ang-2 may be a partial agonist of the receptor. Our paper confirms this weak agonist activity of exogenous Ang-2 and extends their findings by demonstrating that endogenous Ang-2 is critical for basal Tie-2 activity in cultured ECs and that exogenous Ang-2 inhibits Ang-1-induced Tie-2 activation, thus acting as a partial antagonist as well.