title: Clustering of Helicobacter pylori VacA in lipid rafts, mediated by its receptor, receptor-like protein tyrosine phosphatase beta, is required for intoxication in AZ-521 Cells.
abstract: Helicobacter pylori vacuolating cytotoxin, VacA, induces multiple effects on epithelial cells through different cellular events: one involves pore formation, leading to vacuolation, mitochondrial damage, and apoptosis, and the second involves cell signaling, resulting in stimulation of proinflammatory responses and cell detachment. Our recent data demonstrated that VacA uses receptor-like protein tyrosine phosphatase beta (RPTPbeta) as a receptor, of which five residues (QTTQP) at positions 747 to 751 are involved in binding. In AZ-521 cells, which mainly express RPTPbeta, VacA, after binding to RPTPbeta in non-lipid raft microdomains on the cell surface, is localized with RPTPbeta in lipid rafts in a temperature- and VacA concentration-dependent process. Methyl-beta-cyclodextrin (MCD) did not block binding to RPTPbeta but inhibited translocation of VacA with RPTPbeta to lipid rafts and all subsequent events. On the other hand, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), which disrupts anion channels, did not inhibit translocation of VacA to lipid rafts or VacA-induced activation of p38 mitogen-activated protein (MAP) kinase, but inhibited VacA internalization followed by vacuolation. Thus, p38 MAP kinase activation did not appear to be required for internalization. In contrast, phosphatidylinositol-specific phospholipase C (PI-PLC) inhibited translocation, as well as p38 MAP kinase/ATF-2 activation, internalization, and VacA-induced vacuolation. Neither NPPB nor PI-PLC affected VacA binding to cells and to its receptor, RPTPbeta. Thus, receptor-dependent translocation of VacA to lipid rafts is critical for signaling pathways leading to p38 MAP kinase/ATF-2 activation and vacuolation.
authors.affiliation: Department of Bacteriology, Institute of Tropical Medicine, Nagasaki University, Nagasaki 8528523, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nakayama
authors.forename: Jyunzo
authors.initials: J
authors.lastname: Hisatsune
authors.forename: Eiki
authors.initials: E
authors.lastname: Yamasaki
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Nishi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Wada
authors.forename: Hisao
authors.initials: H
authors.lastname: Kurazono
authors.forename: Jan
authors.initials: J
authors.lastname: Sap
authors.forename: Kinnosuke
authors.initials: K
authors.lastname: Yahiro
authors.forename: Joel
authors.initials: J
authors.lastname: Moss
authors.forename: Toshiya
authors.initials: T
authors.lastname: Hirayama
mesh_terms: D051698:Activating Transcription Factor 2 / Q000819:agonists / Q000378:metabolism; D001426:Bacterial Proteins / Q000032:analysis / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000378:metabolism*; D009579:Nitrobenzoates / Q000494:pharmacology; D043265:Phosphatidylinositol Diacylglycerol-Lyase / Q000494:pharmacology; D054801:Phosphoinositide Phospholipase C; D021381:Protein Transport / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000378:metabolism*; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5; D014617:Vacuoles / Q000737:chemistry / Q000378:metabolism*; D047392:beta-Cyclodextrins / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism
chemical_list: C497105:ATF2 protein, human; D051698:Activating Transcription Factor 2; D001426:Bacterial Proteins; D009419:Nerve Tissue Proteins; D009579:Nitrobenzoates; C074689:VacA protein, Helicobacter pylori; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D048051:p38 Mitogen-Activated Protein Kinases; C516895:PTPRZ1 protein, human; D017027:Protein Tyrosine Phosphatases; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase