The αvβ3 Integrin Regulates α5β1-mediated Cell Migration toward Fibronectin

This study examines the interactions of αvβ3 and α5β1 in the regulation of cell migration. Human embryonic kidney (HEK) 293 cells that express α5β1 endogenously were transfected with αvβ3 and β3 mutants, and their attachment and migration to fibronectin (Fn) and vitronectin (Vn) were measured. An αvβ3 blocking antibody and the αvβ3 ligand cyclic G-Pen-GRGDSPC-A inhibited α5β1-mediated migration toward Fn, but not attachment to Fn. This function was αvβ3-specific since αvβ5 transfection and αvβ5 blocking antibody did not produce this effect. Mutations introduced into the β3 integrin subunit to dissect this phenomenon revealed the following. Disruption of the ligand binding domain by the Glanzmann thrombasthenia mutation β3-D119Y constitutively abolished migration toward both Vn and Fn, and attachment to Vn but not to Fn. Insertion of the Glanzmann mutation β3-S752P into the cytoplasmic domain or its truncation (β3-Δ717) abolished binding to Vn but not to Fn. Inhibition of migration toward Fn was inhibited in these cells by αvβ3 blocking antibody. αvβ3-mediated inhibition was, however, abolished by truncation of the transmembrane domain (β3-Δ693). These findings demonstrate αvβ3 regulation of α5β1-mediated cell migration and suggest that the β3 transmembrane domain is essential for this function.