Beyond tie-ing up endothelial adhesion: new insights into the action of angiopoietin-1 in regulation of microvessel permeability.

摘要

The growth factor angiopoietin-1 (Ang1) has been identified as the primary activating ligand for Tie2, a tyrosine kinase receptor highly expressed in vascular endothelial cells. Genetic studies using targeted mutations in mice have demonstrated that Tie2 activation by Ang1 is crucial for angiogenesis, vascular remodelling, and vascular maturation. However, the angiogenic functions of Ang1 are distinct from those of vascular endothelial growth factor (VEGF). Transgenic mice studies have revealed that blood vessels induced by VEGF overexpression are leaky, whereas blood vessels induced by Ang1 overexpression are not only non-leaky, but also resistant to vascular leakage during inflammation.