Helicobacter pylori VacA cytotoxin interacts with fibronectin and alters HeLa cell adhesion and cytoskeletal organization in vitro

Helicobacter pylori vacuolating cytotoxin VacA causes multiple effects on epithelial cell function and morphology, but the effects of VacA on signal transduction pathways and the cytoskeleton have not been investigated in detail. In this study, we analyzed the effects of native VacA on HeLa and AGS cell adhesion to fibronectin and laminin under serum-free conditions. Confocal microscopic examination revealed increased number of cells with rounded morphology and inhibition of actin fiber formation, in the presence of VacA. VacA binds to fibronectin in vitro in a dose-dependent manner. This interaction was partly inhibited by a peptide containing an arginine-glycine-aspartic acid motif. The adhesion of HeLa cells to fibronectin, but not to laminin, was decreased in the presence of VacA. Thus, VacA may interact with fibronectin and influence integrin receptor-induced cell signaling and cytoskeleton-dependent cell functions.