Vacuolation induced by cytotoxin from Helicobacter pylori is mediated by the EGF receptor in HeLa cells.

ABSTRACT

The bacterial toxin VacA produced by H. pylori induces large vacuoles in several types of cultured cells such as HeLa cells or gastric cells. To determine the mechanism of vacuolation induced by this toxin we employed several inhibitors of membrane trafficking and endocytosis. The development of vacuolation induced by VacA in HeLa cells were prevented by bafilomycin A1 and low temperature conditions that inhibited vesicle transport or endocytosis. Formation of large vacuoles was also inhibited by an antibody against EGF receptor, which was previously shown to be internalized by endocytosis, but not by an anti-transferrin receptor antibody. Moreover, proteins of 58 and 37 kDa, corresponding to fragments of VacA, were recognized by an anti-H. pylori antibody after immunoprecipitation with anti-EGF receptor of cell extracts from HeLa cells treated with VacA, but not from untreated HeLa cells. We suggest that VacA may enter cells by endocytosis mediated by the EGF receptor. These are the first data indicating that the EGF receptor may be significant in the development of vacuolation caused by VacA.