Dynamin is involved in human epithelial cell vacuolation caused by the Helicobacter pylori-produced cytotoxin VacA

The Helicobacter pylori-produced cytotoxin VacA induces intracellular vacuo lation. To elucidate the molecular mechanism of vacuole formation by VacA, we examined the participation of dynamin, a GTPase functioning in intracell ular vesicle formation, in human HeLa cells. Immunocytochemistry revealed t hat endogenous dynamin was localized to vacuoles induced by VacA, In cells transiently transfected with a GTPase-defective (dominant-negative) dynamin mutant, VacA Failed to induce vacuolation. In contrast, VacA did induce va cuolation in cells transiently transfected with wild-type dynamin, Furtherm ore, under VacA treatment, neutral red dye uptake, a parameter of VacA-indu ced vacuolation, was inhibited in cells stably transfected with the dominan t-negative dynamin mutant. In contrast, uptake was markedly enhanced in cel ls stably transfected with wild-type dynamin. Moreover, VacA cytopathic eff ects on the viability of HeLa cells were inhibited in cells stably transfec ted with dominant-negative dynamin-1. Sequential immunocytochemical observa tion confirmed that expression of dominant-negative dynamin did not affect VacA attachment to or internalization into HeLa cells. We suggest that dyna min is involved in the intracellular vacuolation induced by VacA.