title: Listeria monocytogenes induced Rac1-dependent signal transduction in endothelial cells.
abstract: Infection of endothelial cells by Listeria monocytogenes is an essential step in the pathogenesis of listeriosis. Small GTPases of the Rho family act as molecular switches in signal transduction. We tested the hypothesis that Rho GTPases contribute to the regulation of cytokine expression following L. monocytogenes infection. L. monocytogenes induced release of distinct CC and CXC, as well as Th1 and Th2 cytokines and growth factors by endothelial cells and activated RhoA and Rac1. Inhibition of Rac1 by inhibitor Nsc23766 reduced cytokine expression, and slightly yet significantly the uptake of bacteria. Blocking of Rho proteins by Clostridium difficile toxin B-10463 (TcdB) reduced Listeria-dependent cytokine expression, whereas activating Rho proteins by Escherichia coli CNF1 increased it. We analyzed regulation of IL-8 expression in more detail: Listeria-induced IL-8 release was reduced by inhibition of RhoA, Rac1 and Cdc42 (TcdB) or Rac1 while blocking of RhoA/B/C by Clostridium limosum C3 fusion toxin (C3FT) or Rho kinase by Y27632 reduced cytokine expression only slightly. Activation of RhoA, Rac1 and Cdc42 (CNF1), but not of RhoA alone (CNF(Y)), enhanced Listeria-dependent IL-8 release significantly. Furthermore, inhibition of RhoA, Rac1 and Cdc42 (TcdB) and Rac1 (Nsc23766), but not of RhoA (C3FT) reduced Listeria-related recruitment of NF-kappaB/p65 and RNA polymerase II to the il8 promoter, as well as acetylation of histone H4 and Ser10/Lys14-phosphorylation/acetylation of histone H3 at the il8 gene promoter in HUVEC. In conclusion, Rac1 contributed to L. monocytogenes-induced cytokine expression by human endothelial cells.
authors.affiliation: Department of Internal Medicine/Infectious Diseases and Respiratory Medicine, Charité, Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Schmeck
authors.forename: Wiebke
authors.initials: W
authors.lastname: Beermann
authors.forename: Vincent
authors.initials: V
authors.lastname: van Laak
authors.forename: Bastian
authors.initials: B
authors.lastname: Opitz
authors.forename: Andreas C
authors.initials: AC
authors.lastname: Hocke
authors.forename: Karolin
authors.initials: K
authors.lastname: Meixenberger
authors.forename: Julia
authors.initials: J
authors.lastname: Eitel
authors.forename: Trinad
authors.initials: T
authors.lastname: Chakraborty
authors.forename: Gudula
authors.initials: G
authors.lastname: Schmidt
authors.forename: Holger
authors.initials: H
authors.lastname: Barth
authors.forename: Norbert
authors.initials: N
authors.lastname: Suttorp
authors.forename: Stefan
authors.initials: S
authors.lastname: Hippenstiel
mesh_terms: D000634:Aminoquinolines / Q000494:pharmacology; D001426:Bacterial Proteins / Q000494:pharmacology; D001427:Bacterial Toxins / Q000494:pharmacology; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000382:microbiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D029968:Escherichia coli Proteins / Q000494:pharmacology; D006801:Humans; D008089:Listeria monocytogenes / Q000472:pathogenicity*; D011743:Pyrimidines / Q000494:pharmacology; D015398:Signal Transduction; D014471:Umbilical Veins / Q000187:drug effects / Q000201:enzymology* / Q000382:microbiology; D020830:rac1 GTP-Binding Protein / Q000096:biosynthesis*
chemical_list: D000634:Aminoquinolines; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D016207:Cytokines; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; C487513:NSC 23766; D011743:Pyrimidines; C031815:toxB protein, Clostridium difficile; C060296:cytotoxic necrotizing factor type 1; D020830:rac1 GTP-Binding Protein