High resolution

Module 9: Figure angiogenesis signalling

Angiogenesis signalling mechanisms.

Angiogenesis, begins when one of the endothelial cells responds to vascular endothelial growth factor (VEGF) by differentiating into a tip cell. The latter then releases platelet-derived growth factor B (PDGF-B) to stimulate the proliferation of neighbouring endothelial cells and pericytes and it recruits the Notch signalling pathway to inhibit these other cells from becoming tip cells. This signalling is restricted to a local region around the tip cell because the PDGF is prevented from diffusing away by being bound to heparan sulphate proteoglycans (HSPGs). The activated endothelial cells release sphingosine 1-phosphate (S1P) and angiopoietin 2 (Ang-2). See text for further details.