title: Salmonella typhimurium SipA-induced neutrophil transepithelial migration: involvement of a PKC-alpha-dependent signal transduction pathway.
abstract: Salmonella typhimurium elicits an intense proinflammatory response characterized by movement of polymorphonuclear neutrophils (PMN) across the epithelial barrier to the intestinal lumen. We previously showed that S. typhimurium, via the type III secretion system effector protein SipA, initiates an ADP-ribosylation factor-6- and phospholipase D-dependent lipid-signaling cascade that directs activation of protein kinase C (PKC) and subsequent transepithelial movement of PMN. Here we sought to determine the specific PKC isoforms that are induced by the S. typhimurium effector SipA in model intestinal epithelia and to link the functional consequences of these isoforms in the promotion of PMN transepithelial migration. In vitro kinase PKC activation assays performed on polarized monolayers of T84 cells revealed that S. typhimurium and recombinant SipA induced activation of PKC-alpha, -delta, and -epsilon. To elucidate which of these isoforms play a key role in mediating epithelial cell responses that lead to the observed PMN transepithelial migration, we used a variety of PKC inhibitors with different isoform selectivity profiles. Inhibitors selective for PKC-alpha (Gö-6976 and 2,2',3,3',4,4'-hexahydroxyl-1,1'-biphenyl-6,6'-dimethanoldimethyl ether) markedly reduced S. typhimurium- and recombinant SipA-induced PMN transepithelial migration, whereas inhibitors to PKC-delta (rottlerin) or PKC-epsilon (V1-2) failed to exhibit a significant decrease in transepithelial movement of PMN. These results were confirmed biochemically and by immunofluorescence coupled to confocal microscopy. Our results are the first to show that the S. typhimurium effector protein SipA can activate multiple PKC isoforms, but only PKC-alpha is involved in the signal transduction cascade leading to PMN transepithelial migration.
authors.affiliation: Combined Program in Pediatric Gastroenterology and Nutrition, Massachusetts General Hospital, Boston, 02129, USA.
authors.forename: Milton
authors.initials: M
authors.lastname: Silva
authors.forename: Cecilia
authors.initials: C
authors.lastname: Song
authors.forename: William J
authors.initials: WJ
authors.lastname: Nadeau
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Matthews
authors.forename: Beth A
authors.initials: BA
authors.lastname: McCormick
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D001426:Bacterial Proteins / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002227:Carbazoles / Q000494:pharmacology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008566:Membranes / Q000378:metabolism; D008840:Microfilament Proteins / Q000494:pharmacology*; D020556:Neutrophil Infiltration / Q000187:drug effects* / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D011994:Recombinant Proteins / Q000494:pharmacology; D012486:Salmonella typhimurium / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D000089982:ADP-Ribosylation Factor 6; D001426:Bacterial Proteins; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D008840:Microfilament Proteins; D011994:Recombinant Proteins; C118287:SipA protein, Salmonella; C081021:Go 6976; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; C000715348:ARF6 protein, human