Integrin β3 Crosstalk with VEGFR Accommodating Tyrosine Phosphorylation as a Regulatory Switch

Integrins mediate cell adhesion, migration, and survival by connecting intracellular machinery with the surrounding extracellular matrix. Previous studies demonstrated the importance of the interaction between beta(3) integrin and VEGF type 2 receptor (VEGFR2) in VEGF-induced angiogenesis. Here we present in vitro evidence of the direct association between the cytoplasmic tails (CTs) of beta(3) and VEGFR2. Specifically, the membrane-proximal motif around (YLSI)-Y-801 in VEGFR2 mediates its binding to non-phosphorylated beta 3CT, accommodating an alpha-helical turn in integrin bound conformation. We also show that Y-747 phosphorylation of beta(3) enhances the above interaction. To demonstrate the importance of beta(3) phosphorylation in endothelial cell functions, we synthesized beta 3CT-mimicking Y-747 phosphorylated and unphosphorylated membrane permeable peptides. We show that a peptide containing phospho-Y-747 but not F-747 significantly inhibits VEGF-induced signaling and angiogenesis. Moreover, phospho-Y-747 peptide exhibits inhibitory effect only in WT but not in beta(3) integrin knock-out or beta(3) integrin knock-in cells expressing beta(3) with two tyrosines substituted for phenylalanines, demonstrating its specificity. Importantly, these peptides have no effect on fibroblast growth factor receptor signaling. Collectively these data provide novel mechanistic insights into phosphorylation dependent cross-talk between integrin and VEGFR2.