title: Adenylate cyclase toxin subverts phagocyte function by RhoA inhibition and unproductive ruffling.
abstract: Adenylate cyclase toxin (CyaA or ACT) is a key virulence factor of pathogenic Bordetellae. It penetrates phagocytes expressing the alpha(M)beta(2) integrin (CD11b/CD18, Mac-1 or CR3) and paralyzes their bactericidal capacities by uncontrolled conversion of ATP into a key signaling molecule, cAMP. Using pull-down activity assays and transfections with mutant Rho family GTPases, we show that cAMP signaling of CyaA causes transient and selective inactivation of RhoA in mouse macrophages in the absence of detectable activation of Rac1, Rac2, or RhoG. This CyaA/cAMP-induced drop of RhoA activity yielded dephosphorylation of the actin filament severing protein cofilin and massive actin cytoskeleton rearrangements, which were paralleled by rapidly manifested macrophage ruffling and a rapid and unexpected loss of macropinocytic fluid phase uptake. As shown in this study for the first time, CyaA/cAMP signaling further caused a rapid and near-complete block of complement-mediated phagocytosis. Induction of unproductive membrane ruffling, hence, represents a novel sophisticated mechanism of down-modulation of bactericidal activities of macrophages and a new paradigm for action of bacterial toxins that hijack host cell signaling by manipulating cellular cAMP levels.
authors.affiliation: Cellular and Molecular Microbiology Division, Institute of Microbiology of the Academy of Sciences of the Czech Republic, Prague 4, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Kamanova
authors.forename: Olga
authors.initials: O
authors.lastname: Kofronova
authors.forename: Jiri
authors.initials: J
authors.lastname: Masin
authors.forename: Harald
authors.initials: H
authors.lastname: Genth
authors.forename: Jana
authors.initials: J
authors.lastname: Vojtova
authors.forename: Irena
authors.initials: I
authors.lastname: Linhartova
authors.forename: Oldrich
authors.initials: O
authors.lastname: Benada
authors.forename: Ingo
authors.initials: I
authors.lastname: Just
authors.forename: Peter
authors.initials: P
authors.lastname: Sebo
mesh_terms: D008841:Actin Cytoskeleton / Q000276:immunology / Q000378:metabolism; D051339:Actin Depolymerizing Factors / Q000276:immunology / Q000378:metabolism; D037361:Adenylate Cyclase Toxin / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D001886:Bordetella pertussis / Q000201:enzymology / Q000276:immunology*; D039481:CD11b Antigen / Q000235:genetics / Q000276:immunology; D018821:CD18 Antigens / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D000242:Cyclic AMP / Q000276:immunology; D005260:Female; D020558:GTP Phosphohydrolases / Q000276:immunology / Q000378:metabolism; D016177:Macrophage-1 Antigen / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D009479:Neuropeptides / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*; D014917:Whooping Cough / Q000201:enzymology / Q000276:immunology*; D020744:rac GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins / Q000276:immunology* / Q000378:metabolism; D020742:rhoA GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein
chemical_list: D051339:Actin Depolymerizing Factors; D037361:Adenylate Cyclase Toxin; D039481:CD11b Antigen; D018821:CD18 Antigens; D000242:Cyclic AMP; D020558:GTP Phosphohydrolases; D016177:Macrophage-1 Antigen; D009479:Neuropeptides; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein; C484602:Rac1 protein, mouse; C489577:Rhog protein, mouse; C526380:RhoA protein, mouse