Stimulation of beta(1) integrin induces tyrosine phosphorylation of vascular endothelial growth factor receptor-3 and modulates cell migration

Interactions between integrins and tyrosine kinase receptors can modulate a variety of cell functions. We observed a cooperative interaction between t he beta(1) integrin and vascular endothelial growth factor receptor-3 (VEGF R-3 or Flt4) that appeared to be required for cell migration. By using VEGF R-3-transfected 293 cells (293/VEGFR-3) or primary dermal microvascular end othelial cells (DMEC), we found that stimulation with either soluble or imm obilized extracellular matrix (ECM) proteins, collagen or fibronectin (FN), resulted in the increased tyrosine phosphorylation of VEGFR-3 in the absen ce of a cognate ligand. This increased tyrosine phosphorylation of VEGFR-3 was diminished by pretreatment with a blocking antibody against the beta(1) integrin. Cross-linking with anti-beta(1) integrin antibody induced a simi lar degree of tyrosine phosphorylation of VEGFR-3. Stimulation with collage n or FN induced an association between beta(1) integrin and VEGFR-3 in both 293/VEGFR-3 and primary DMEC cells. Collagen or FN-induced tyrosine phosph orylation of VEGFR-3 was inhibited by treatment with cytochalasin D, an inh ibitor of actin polymerization. Collagen or FN was able to induce the migra tion of 293/VEGFR-3 or DMEC cells to a limited extent. However, migration w as dramatically enhanced when a gradient of the cognate ligand, VEGF-D, was added. VEGF-D failed to induce cell migration in the absence of ECM protei ns. Introducing a mutation at the kinase domain of VEGFR-3 or treatment wit h blocking antibody against either VEGFR-3 or beta(1) integrin inhibited ce ll migration induced by ECM and VEGF-D, indicating that signals from both b eta(1) integrin and VEGFR-3 are required for this cell function.