Protein-tyrosine Phosphatase , RPTP ,I s aHelicobacter pylori VacA Receptor*

Helicobacter pylori vacuolating cytotoxin, VacA, induces vacuolation, mitochondrial damage, cytochrome c release, and apoptosis of gastric epithelial cells. To detect gastric proteins that serve as VacA receptors, we used VacA co-immunoprecipitation techniques following biotinylation of the cell surface and identified p250, a receptor-like protein-tyrosine phosphatase (RPTP) as a VacA-binding protein (Yahiro, K., Niidome, T., Kimura, M., Hatakeyama, T., Aoyagi, H., Kurazono, H., Imagawa, K., Wada, A., Moss, J., and Hirayama, T. (1999) J. Biol. Chem. 274, 36693–36699). VacA causes vacuolation of G401 cells, a human kidney tumor cell line, although they do not express RPTP. By co-immunoprecipitation with VacA, we identified p140 as a potential receptor in those cells. p140 purified by chromatography on a peanut agglutinin affinity matrix contained internal amino acid sequences of RGEENTDYVNASFIDGYRQK and AEGILDVFQTVK, which are identical to those in RPTP. The peptide mass fingerprinting of p140 by time of flight-MS analysis also supported this identification. Treatment of G401 cells with RPTP-morpholino antisense oligonucleotide before exposure to toxin inhibited vacuolation. These data suggest that RPTP acts as a receptor for VacA in G401 cells. Thus, two receptor tyrosine phosphatases, RPTP and RPTP, serve as VacA receptors.