| Target Description | The angiopoietin (Ang)-Tie ligand-receptor system has a key role in regulating vascular integrity and quiescence. Besides its role in angiogenesis it is an important regulator in numerous diseases including inflammation. Ang-1-mediated Tie2 activation is required to maintain the quiescent resting state of the endothelium. In contrast, Ang-2 destabilizes the quiescent endothelium and primes it to respond to exogenous stimuli, thereby facilitating the activities of inflammatory and angiogenic cytokines. Intriguingly, Ang-2 is expressed weakly by the resting endothelium but becomes strongly upregulated following endothelial activation. Moreover, endothelial cells store Ang-2 in Weibel-Palade bodies from where it can be made available quickly following stimulation, suggesting a role of Ang-2 in controlling rapid vascular adaptive processes. This suggests that Ang-2 functions as a built-in switch controlling the transition of the resting quiescent endothelium towards the activated responsive endothelium. |
