A Jagged1/Notch interaction drives integrin αvβ3 expression in VSMCs. (A) VSMC culture on a Jag1-coated substrate increased mRNA expression of integrin β3 5.3-fold by qPCR (± 0.7; n = 6). Culture on Jag1 also up-regulated canonical Notch-downstream genes HES1 (3.4 ± 1.4, n = 3) and HEY2 (2.4 ± 0.5, n = 4). (B) FACS analysis of VSMCs found that surface expression of integrin αvβ3 increased 3-fold in response to culture on a Jag1-coated substrate. (C) Representative images of retinas from mice treated with vehicle (DMSO) or DAPT to block Notch signaling from P3-P6, and analyzed P7. Retinas were immunostained with Abs against integrin β3 (green) and αSMA (red) to label VSMCs, and CD31 (blue) to label endothelial cells. DAPT treatment inhibited the expression of αvβ3 in arterial-associated VSMCs, but did not inhibit the expression of αvβ3 in the sprouting angiogenic tip cells. Values represent means ± SEM, 2^ΔΔCT analysis. Scale bar: 50 μm.