Requirement of the NPXY motif in the integrin β3 subunit cytoplasmic tail for melanoma cell migration in vitro and in vivo

Abstract

The NPXY sequence is highly conserved among integrin β subunit cytoplasmic tails, suggesting that it plays a fundamental role in regulating integrin-mediated function. Evidence is provided that the NPXY structural motif within the β3 subunit, comprising residues 744-747, is essential for cell morphological and migratory responses mediated by integrin αvβ3 in vitro and in vivo. Transfection of CS-1 melanoma cells with a cDNA encoding the wild-type integrin β3 subunit, results in de novo αvβ3 expression and cell attachment, spreading, and migration on vitronectin. CS-1 cells expressing αvβ3 with mutations that disrupt the NPXY sequence interact with soluble vitronectin or an RGD peptide, yet fail to attach, spread, or migrate on immobilized ligand. The biological consequences of these observations are underscored by the finding that CS-1 cells expressing wild-type αvβ3 acquire the capacity to form spontaneous pulmonary metastases in the chick embryo when grown on the chorioallantoic membrane. However, migration- deficient CS-1 cells expressing αvβ3 with mutations in the NPXY sequence lose this ability to metastasize. These findings demonstrate that the NPXY motif within the integrin β3 cytoplasmic tail is essential for αvβ3- dependent post-ligand binding events involved in cell migration and the metastatic phenotype of melanoma cells.