Wortmannin blocks Yersinia invasin-triggered internalization, but not interleukin-8 production by epithelial cells

Abstract

In response to bacterial infection epithelial cells up-regulate expression and secretion of proinflammatory cytokines. Previous work from our laboratory showed that basolateral infection of polarized T84 cells with Yersinia enterocolitica induces interleukin-8 (IL-8) secretion in the absence of significant invasion. Here we studied Y. enterocolitica-induced IL-8 secretion by epithelial HeLa cells as a function of Yersinia invasion or adhesion. For this purpose we tried to separated induction of IL-8 secretion from invasion by treating HeLa cells with signal transduction inhibitors prior to infection. While staurosporin and genistein inhibited both Yersinia invasion and Yersinia-triggered IL-8 secretion, wortmannin, an inhibitor of the phosphatidylinositol-3-phosphate kinase (PI3-K), blocked invasion of Y. enterocolitica into HeLa cells but did not show any effect on IL-8 secretion. These results suggest that Yersinia adhesion might be sufficient to induce IL-8 secretion by epithelial cells. Further analysis demonstrated the requirement of the Yersinia invasion locus inv for adhesion-mediated induction of IL-8 secretion. Thus, HeLa cells infected with an E. coli strain expressing the Y. enterocolitica inv locus induced IL-8 secretion in the presence and absence of wortmannin. Reverse transcription-polymerase chain reaction analysis revealed that adhesion of inv-expressing Y. enterocolitica or E. coli results in the transcriptional activation of the IL-8 gene. These results suggest that Y. enterocolitica adhesion to host cells via Inv activates de novo synthesis and secretion of IL-8.

The YadA Protein ofYersinia pseudotuberculosisMediates High-Efficiency Uptake into Human Cells under Environmental Conditions in Which Invasin Is Repressed

“…7D). These results were similar to those obtained with the invasin-expressing E. coli strain and are in full agreement with previous studies on invasin-mediated uptake of yersiniae (37,49). We conclude that YadA-promoted cell entry, like invasin-promoted cell entry, occurs through a PI3K-dependent signaling pathway and requires phosphokinases and actin polymerization.…”

“…A signaling protein that couples tyrosine phosphorylation events to actin rearrangements during bacterial entry is PI3K (10). PI3K has been shown to be involved in the internalin Band invasin-mediated uptake processes of Listeria monocytogenes and Y. enterocolitica, respectively (9,49). To investigate whether activation of this PI3K activity is also required for YadA-mediated uptake, we tested the effect of the PI3K inhibitor wortmannin on entry via YadA.…”

Specific Entry ofHelicobacter pyloriinto Cultured Gastric Epithelial Cells via a Zipper-Like Mechanism

“…Since pathogens such as N. gonorrhoeae are able to efficiently trigger ␣ v ␤ 5 -integrin-mediated uptake by binding directly to vitronectin (26), it is quite possible that the binding of serum factors such as vitronectin by H. pylori may further stimulate entry into AGS cells via the ␤1-integrin-mediated signaling pathway. (41,72). One of the adhesins of Listeria, InlB, was shown to trigger the activation of PI 3-kinase and the association of the p85 regulatory subunit of PI 3-kinase with Gab1, Cbl, and Shc kinases (41,42).…”

Novel PI 3-kinase-dependent mechanisms of trypanosome invasion and vacuole maturation

“…Modulation of host cell PI 3-kinase-dependent signaling by microbial pathogens is becoming recognized as an important strategy for establishment of infection and intracellular survival of these organisms (Duclos and Desjardins, 2000;Fratti et al, 2001;Coombes and Mahony, 2002). For instance, PI 3-kinase activation promotes the actin-dependent uptake of Yersinia (Schulte et al, 1998) and Listeria (Ireton et al, 1996) while enteropathogenic E. coli prevents its own phagocytic uptake by thwarting PI 3-kinase signaling in macrophages (Celli et al, 2001). Moreover, the ability of some pathogens to survive within an intracellular vacuolar compartment involves pathogen-specific strategies for manipulation of the phagosome maturation process at different stages (Xu et al, 1994;Sinai and Joiner, 1997;Scianimanico et al, 1999;SteeleMortimer et al, 1999;Hackstadt, 2000;Fratti et al, 2001).…”