Integrin β 3 crosstalk with VEGFR accommodating tyrosine phosphorylation as a regulatory switch

Abstract

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 β 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 β 3 and VEGFR2. Specifically, the membrane-proximal motif around 801YLSI in VEGFR2 mediates its binding to non-phosphorylated β 3CT, accommodating an α-helical turn in integrin bound conformation. We also show that Y 747 phosphorylation of β 3 enhances the above interaction. To demonstrate the importance of β 3 phosphorylation in endothelial cell functions, we synthesized β 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 β 3 integrin knock-out or β 3 integrin knock-in cells expressing β 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. © 2012 West et al.