Notch promotes vascular maturation by inducing integrin-mediated smooth muscle cell adhesion to the endothelial basement membrane

Vascular development and angiogenesis initially depend on endothelial tip cell invasion, which is followed by a series of maturation steps, including lumen formation and recruitment of perivascular cells. Notch ligands expressed on the endothelium and their cognate receptors expressed on perivascular cells are involved in blood vessel maturation, though little is known regarding the Notch-dependent effectors that facilitate perivascular coverage of nascent vessels. Here, we report that vascular smooth muscle cell (VSMC) recognition of the Notch ligand Jagged1 on endothelial cells leads to expression of integrin alpha v beta 3 on VSMCs. Once expressed, integrin alpha v beta 3 facilitates VSMC adhesion to VWF in the endothelial basement membrane of developing retinal arteries, leading to vessel maturation. Genetic or pharmacologic disruption of Jagged1, Notch, alpha v beta 3, or VWF suppresses VSMC coverage of nascent vessels and arterial maturation during vascular development. Therefore, we define a Notch-mediated interaction between the developing endothelium and VSMCs leading to adhesion of VSMCs to the endothelial basement membrane and arterial maturation. (Blood. 2012; 119(9):2149-2158)