title: Pasteurella multocida toxin selectively facilitates phosphatidylinositol 4,5-bisphosphate hydrolysis by bombesin, vasopressin, and endothelin. Requirement for a functional G protein.
abstract: Treatment of Swiss 3T3 cells with a subsaturating concentration of recombinant Pasteurella multocida toxin (rPMT) markedly potentiated the production of inositol phosphates induced by bombesin, vasopressin, and endothelin but not by platelet-derived growth factor (PDGF) (AA and BB homodimers). Similarly, the neuropeptides but not PDGF caused a shift in the dose-dependent increase in inositol phosphates induced by rPMT. The rate of accumulation of inositol phosphates induced by bombesin was increased 2-fold by rPMT treatment while that of PDGF was unaffected. rPMT treatment also enhanced bombesin-induced inositol(1,4,5)trisphosphate, the direct product of phosphatidylinositol 4,5-bisphosphate hydrolysis. In contrast, treatment of cells with rPMT had no effect on the tyrosine phosphorylation of phospholipase C gamma. Depletion of protein kinase C increased rPMT-induced inositol phosphates in a manner similar to that observed for bombesin but not PDGF. Thus, rPMT selectively potentiates neuropeptide-mediated inositol phosphate production. The action of rPMT on phosphatidylinositol 4,5-bisphosphate hydrolysis persisted in streptolysin O-permeabilized cells. Addition of guanosine 5'-O-(beta-thiodiphosphate) to permeabilized cells markedly reduced rPMT-induced inositol phosphates in a time- and dose-dependent manner. rPMT also increased the sensitivity of phospholipase C for free calcium. Our results strongly suggest that the action of rPMT facilitates the coupling of G protein to phospholipase C.
authors.affiliation: Imperial Cancer Research Fund, London, United Kingdom.
authors.forename: A C
authors.initials: AC
authors.lastname: Murphy
authors.forename: E
authors.initials: E
authors.lastname: Rozengurt
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000494:pharmacology*; D001839:Bombesin / Q000494:pharmacology*; D002463:Cell Membrane Permeability; D016232:Endothelins / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006868:Hydrolysis; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000276:immunology; D010325:Pasteurella; D019269:Phosphatidylinositol 4,5-Diphosphate; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010716:Phosphatidylinositols / Q000378:metabolism*; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013873:Thionucleotides / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D016232:Endothelins; D007328:Insulin; D046911:Macromolecular Substances; D009842:Oligopeptides; C062258:Pasteurella multocida toxin; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D010982:Platelet-Derived Growth Factor; D011994:Recombinant Proteins; D013873:Thionucleotides; D016222:Fibroblast Growth Factor 2; D014667:Vasopressins; D006153:Guanosine Diphosphate; D004815:Epidermal Growth Factor; C023427:guanosine 5'-O-(2-thiodiphosphate); D010727:Phosphoric Diester Hydrolases; D019204:GTP-Binding Proteins; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D001839:Bombesin