Src kinase phosphorylates vascular endothelial-cadherin in response to vascular endothelial growth factor: identification of tyrosine 685 as the unique target site

Y Wallez, F Cand, F Cruzalegui, C Wernstedt… - Oncogene, 2007 - nature.com
Y Wallez, F Cand, F Cruzalegui, C Wernstedt, S Souchelnytskyi, I Vilgrain, P Huber
Oncogene, 2007nature.com
Src-family tyrosine kinases are regulatory proteins that play a pivotal role in the
disorganization of cadherin-dependent cell–cell contacts. We previously showed that Src
was associated with vascular endothelial (VE)-cadherin and that tyrosine phosphorylation
level of VE-cadherin was dramatically increased in angiogenic tissues as compared to
quiescent tissues. Here, we examined whether VE-cadherin was a direct substrate for Src in
vascular endothelial growth factor (VEGF)-induced VE-cadherin phosphorylation, and we …
Abstract
Src-family tyrosine kinases are regulatory proteins that play a pivotal role in the disorganization of cadherin-dependent cell–cell contacts. We previously showed that Src was associated with vascular endothelial (VE)-cadherin and that tyrosine phosphorylation level of VE-cadherin was dramatically increased in angiogenic tissues as compared to quiescent tissues. Here, we examined whether VE-cadherin was a direct substrate for Src in vascular endothelial growth factor (VEGF)-induced VE-cadherin phosphorylation, and we identified the target tyrosine sites. Co-transfections of Chinese hamster ovary cells (CHO) cells with VE-cadherin and constitutively active Src (Y530F) resulted in a robust tyrosine phosphorylation of VE-cadherin that was not detected with kinase-dead Src (K298M). In an in vitro Src assay, the VE-cadherin cytoplasmic domain is directly phosphorylated by purified Src as well as the tyrosine residue 685 (Tyr) 685-containing peptide RPSLY 685 AQVQ. VE-cadherin peptide mapping from human umbilical vein endothelial cells stimulated by VEGF and VE-cadherin-CHO cells transfected with active Src revealed that Y685 was the unique phosphorylated site. The presence of PhosphoY685 was confirmed by its ability to bind to C-terminal Src kinase-SH2 domain in a pull-down assay. Finally, we found that in a VEGF-induced wound-healing assay, cadherin adhesive activity was impaired by Src kinase inhibitors. These data identify that VEGF-induced-VE-cadherin tyrosine phosphorylation is mediated by Src on Y685, a process that appears to be critical for VEGF-induced endothelial cell migration.
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