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Interferon alpha inhibits a Src-mediated pathway necessary for Shigella-induced cytoskeletal rearrangements in epithelial cells.

Duménil G, Olivo JC, Pellegrini S, Fellous M, Sansonetti PJ, Nhieu GT - J. Cell Biol. (1998)

Bottom Line: Shigella flexneri, the causative agent of bacillary dysentery, has the ability to enter nonphagocytic cells.The interferon (IFN) family of cytokines was found to inhibit Shigella invasion of cultured epithelial cells.Immunofluorescence studies showed that IFN-alpha inhibits Shigella-induced actin polymerization required for bacterial entry into cells.

View Article: PubMed Central - PubMed

Affiliation: Unité de Génétique Humaine, INSERM U276.

ABSTRACT
Shigella flexneri, the causative agent of bacillary dysentery, has the ability to enter nonphagocytic cells. The interferon (IFN) family of cytokines was found to inhibit Shigella invasion of cultured epithelial cells. We show here that IFN-alpha inhibits a Src-dependent signaling cascade triggered by Shigella that leads to the reorganization of the host cell cytoskeleton. Immunofluorescence studies showed that IFN-alpha inhibits Shigella-induced actin polymerization required for bacterial entry into cells. Phosphorylation of cortactin, a Src-substrate specifically tyrosyl-phosphorylated during Shigella entry, was inhibited by IFN-alpha. Overexpression of a dominant interfering form of pp60c-src led to inhibition of Shigella-induced cytoskeletal rearrangements and decreased cortactin phosphorylation indicating a role for Src in Shigella entry. Also, Shigella uptake in cells that expressed constitutively active Src was unaffected by IFN-alpha treatment. We conclude that Src kinase activity is necessary for Shigella invasion of epithelial cells and that IFN-alpha inhibits this Src-dependent signaling pathway.

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Src is responsible for Shigella-induced cortactin phosphorylation. srcK−, srcK+ and control cells (HeLa) were challenged with mxiD− or wild-type (WT) Shigella and their content  in phosphotyrosyl proteins was analyzed by Western blot using  anti-phosphotyrosine mAb. 5, 10, 15, 30, cells challenged with  Shigella for 5, 10, 15, 30 min, respectively; D−, cells challenged  with the Shigella mxiD mutant. Approximately 10 μg of protein  was loaded per lane.
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Figure 6: Src is responsible for Shigella-induced cortactin phosphorylation. srcK−, srcK+ and control cells (HeLa) were challenged with mxiD− or wild-type (WT) Shigella and their content in phosphotyrosyl proteins was analyzed by Western blot using anti-phosphotyrosine mAb. 5, 10, 15, 30, cells challenged with Shigella for 5, 10, 15, 30 min, respectively; D−, cells challenged with the Shigella mxiD mutant. Approximately 10 μg of protein was loaded per lane.

Mentions: Shigella-induced protein phosphorylation was first investigated in these transfectants. Cells transfected with the vector only exhibited the usual kinetics of phosphorylation, with cortactin phosphorylation peaking at 15 min (Fig. 6, HeLa). In contrast, cells overexpressing the dominant interfering form of Src exhibited reduced levels of cortactin phosphorylation that was hardly detectable at early time points and increased slightly at 30 min (Fig. 6, srcK−). Thus, cortactin phosphorylation was markedly reduced in srcK− cells as compared with control cells. The induction of p40 phosphorylation was reduced, although to a lesser extent than that of cortactin, upon overexpression of the dominant interfering form of Src.


Interferon alpha inhibits a Src-mediated pathway necessary for Shigella-induced cytoskeletal rearrangements in epithelial cells.

Duménil G, Olivo JC, Pellegrini S, Fellous M, Sansonetti PJ, Nhieu GT - J. Cell Biol. (1998)

Src is responsible for Shigella-induced cortactin phosphorylation. srcK−, srcK+ and control cells (HeLa) were challenged with mxiD− or wild-type (WT) Shigella and their content  in phosphotyrosyl proteins was analyzed by Western blot using  anti-phosphotyrosine mAb. 5, 10, 15, 30, cells challenged with  Shigella for 5, 10, 15, 30 min, respectively; D−, cells challenged  with the Shigella mxiD mutant. Approximately 10 μg of protein  was loaded per lane.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132965&req=5

Figure 6: Src is responsible for Shigella-induced cortactin phosphorylation. srcK−, srcK+ and control cells (HeLa) were challenged with mxiD− or wild-type (WT) Shigella and their content in phosphotyrosyl proteins was analyzed by Western blot using anti-phosphotyrosine mAb. 5, 10, 15, 30, cells challenged with Shigella for 5, 10, 15, 30 min, respectively; D−, cells challenged with the Shigella mxiD mutant. Approximately 10 μg of protein was loaded per lane.
Mentions: Shigella-induced protein phosphorylation was first investigated in these transfectants. Cells transfected with the vector only exhibited the usual kinetics of phosphorylation, with cortactin phosphorylation peaking at 15 min (Fig. 6, HeLa). In contrast, cells overexpressing the dominant interfering form of Src exhibited reduced levels of cortactin phosphorylation that was hardly detectable at early time points and increased slightly at 30 min (Fig. 6, srcK−). Thus, cortactin phosphorylation was markedly reduced in srcK− cells as compared with control cells. The induction of p40 phosphorylation was reduced, although to a lesser extent than that of cortactin, upon overexpression of the dominant interfering form of Src.

Bottom Line: Shigella flexneri, the causative agent of bacillary dysentery, has the ability to enter nonphagocytic cells.The interferon (IFN) family of cytokines was found to inhibit Shigella invasion of cultured epithelial cells.Immunofluorescence studies showed that IFN-alpha inhibits Shigella-induced actin polymerization required for bacterial entry into cells.

View Article: PubMed Central - PubMed

Affiliation: Unité de Génétique Humaine, INSERM U276.

ABSTRACT
Shigella flexneri, the causative agent of bacillary dysentery, has the ability to enter nonphagocytic cells. The interferon (IFN) family of cytokines was found to inhibit Shigella invasion of cultured epithelial cells. We show here that IFN-alpha inhibits a Src-dependent signaling cascade triggered by Shigella that leads to the reorganization of the host cell cytoskeleton. Immunofluorescence studies showed that IFN-alpha inhibits Shigella-induced actin polymerization required for bacterial entry into cells. Phosphorylation of cortactin, a Src-substrate specifically tyrosyl-phosphorylated during Shigella entry, was inhibited by IFN-alpha. Overexpression of a dominant interfering form of pp60c-src led to inhibition of Shigella-induced cytoskeletal rearrangements and decreased cortactin phosphorylation indicating a role for Src in Shigella entry. Also, Shigella uptake in cells that expressed constitutively active Src was unaffected by IFN-alpha treatment. We conclude that Src kinase activity is necessary for Shigella invasion of epithelial cells and that IFN-alpha inhibits this Src-dependent signaling pathway.

Show MeSH
Related in: MedlinePlus