title: Pasteurella multocida toxin stimulates mitogen-activated protein kinase via G(q/11)-dependent transactivation of the epidermal growth factor receptor.
abstract: The dermatonecrotic toxin produced by Pasteurella multocida is one of the most potent mitogenic substances known for fibroblasts in vitro. Exposure to recombinant P. multocida toxin (rPMT) causes phospholipase C-mediated hydrolysis of inositol phospholipids, calcium mobilization, and activation of protein kinase C via a poorly characterized mechanism involving G(q/11) family heterotrimeric G proteins. To determine whether the regulation of G protein pathways contributes to the mitogenic effects of rPMT, we have examined the mechanism whereby rPMT stimulates the Erk mitogen-activated protein kinase cascade in cultured HEK-293 cells. Treatment with rPMT resulted in a dose and time-dependent increase in Erk 1/2 phosphorylation that paralleled its stimulation of inositol phospholipid hydrolysis. Both rPMT- and alpha-thrombin receptor- stimulated Erk phosphorylation were selectively blocked by cellular expression of two peptide inhibitors of G(q/11) signaling, the dominant negative mutant G protein-coupled receptor kinase, GRK2(K220R), and the Galpha(q) carboxyl-terminal peptide, Galpha(q)-(305-359). Like alpha-thrombin receptor-mediated Erk activation, the effect of rPMT was insensitive to the protein kinase C inhibitor GF109203X, but was blocked by the epidermal growth factor receptor-specific tyrphostin, AG1478 and by dominant negative mutants of mSos1 and Ha-Ras. These data indicate that rPMT employs G(q/11) family heterotrimeric G proteins to induce Ras-dependent Erk activation via protein kinase C-independent "transactivation" of the epidermal growth factor receptor.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: B
authors.initials: B
authors.lastname: Seo
authors.forename: E W
authors.initials: EW
authors.lastname: Choy
authors.forename: S
authors.initials: S
authors.lastname: Maudsley
authors.forename: W E
authors.initials: WE
authors.lastname: Miller
authors.forename: B A
authors.initials: BA
authors.lastname: Wilson
authors.forename: L M
authors.initials: LM
authors.lastname: Luttrell
mesh_terms: D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D006868:Hydrolysis; D008246:Lysophospholipids / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008934:Mitogens / Q000378:metabolism*; D009154:Mutation; D010716:Phosphatidylinositols / Q000378:metabolism; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface / Q000037:antagonists & inhibitors; D011994:Recombinant Proteins / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology; D013997:Time Factors; D015533:Transcriptional Activation; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000378:metabolism; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D008246:Lysophospholipids; D008934:Mitogens; C062258:Pasteurella multocida toxin; D010716:Phosphatidylinositols; D000075370:Receptors for Activated C Kinase; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D010566:Virulence Factors, Bordetella; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D013917:Thrombin; D019204:GTP-Binding Proteins