Activation of NF-kappaB and IL-8 by Yersinia enterocolitica invasin protein is conferred by engagement of Rac1 and MAP kinase cascades.
Yersinia enterocolitica triggers activation of the nuclear factor (NF)-kappaB and production of the proinflammatory chemokine interleukin (IL)-8 in intestinal epithelial cells. This activation is due to adhesion of the bacteria via their outer membrane protein invasin to the host cells. Using Clostridium difficile toxins that specifically inactivate small GTPases, and transfection of inhibitory proteins of the Rho-GTPases, we demonstrate that Rac1, but not Cdc42 or Rho, is required for activation of NF-kappaB by invasin. Invasin activated the mitogen activated protein kinases (MAPK) p38 and c-Jun N-terminal protein kinase (JNK) but not extracellular signal regulated kinase (ERK). The functional relevance of these pathways for invasin-mediated IL-8 expression was assessed by protein kinase inhibitors and dominant-negative kinase mutants. While NF-kappaB and JNK contribute to IL-8 transcription, p38 MAPK also acts through stabilization of IL-8 mRNA, as confirmed by quantitative RT-PCR and electrophoretic mobility shift assays. Transfection experiments with I-kappaB kinase (IKK)1 and IKK2 mutants indicate that the release of NF-kappaB from its cytoplasmic inhibitor I-kappaB and its translocation into the nucleus is mediated by these kinases. Our data identify Rac1 as a key intermediate in invasin-triggered IL-8 synthesis and demonstrate that maximum IL-8 induction involves several MAP kinase cascades.
Grassl
Guntram A
GA
Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Universitätsklinikum Tübingen, D-72076 Tübingen, Germany.
Kracht
Michael
M
Wiedemann
Agnès
A
Hoffmann
Elke
E
Aepfelbacher
Martin
M
von Eichel-Streiber
Christoph
C
Bohn
Erwin
E
Autenrieth
Ingo B
IB
D018829:Adhesins, Bacterial / Q000378:metabolism / Q000502:physiology*; D001422:Bacterial Adhesion / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D020871:RNA Stability / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000302:isolation & purification; D015398:Signal Transduction; D015008:Yersinia enterocolitica / Q000276:immunology* / Q000472:pathogenicity; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D020743:rhoB GTP-Binding Protein / Q000378:metabolism
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D016209:Interleukin-8; D016328:NF-kappa B; D012333:RNA, Messenger; C053476:invasin, Yersinia; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D020743:rhoB GTP-Binding Protein