Identification of the Salmonella enterica serotype typhimurium SipA domain responsible for inducing neutrophil recruitment across the intestinal epithelium. Cell Microbiol 9(9):2299-2313 Epub 2007 May 18

Mucosal Immunology Laboratory, Department of Pediatric Gastroenterology and Nutrition, Massachusetts General Hospital, Charlestown, MA 02129, USA.
Cellular Microbiology (Impact Factor: 4.92). 10/2007; 9(9):2299-313. DOI: 10.1111/j.1462-5822.2007.00960.x
Source: PubMed


In human intestinal disease induced by Salmonella enterica serotype Typhimurium (S. typhimurium) transepithelial migration of polymorphonuclear leukocytes (PMNs) rapidly follows attachment of the bacteria to the epithelial apical membrane. Previously, we have shown that the S. typhimurium effector protein, SipA, plays a pivotal role in signalling epithelial cell responses that lead to the transepithelial migration of PMNs. Thus, the objective of this study was to determine the functional domain of SipA that regulates this signalling event. SipA was divided into two fragments: the SipAb C-terminal fragment(426-684) (259 AA), which binds actin, and the SipAa fragment(2-425) (424 AA), which a role has yet to be described. In both in vitro and in vivo models of S. typhimurium-induced intestinal inflammation the SipAa fragment exhibited a profound ability to induce PMN transmigration, whereas the SipAb actin-binding domain failed to induce PMN transmigration. Subsequent mapping of the SipAa domain identified a 131-amino-acid region (SipAa3(294-424)) responsible for modulating PMN transepithelial migration. Interestingly, neither intracellular translocation nor actin association of SipA was necessary for its ability to induce PMN transepithelial migration. As these results indicate SipA has at least two separate functional domains, we speculate that during infection S. typhimurium requires delivery of SipA to both extracellular and intracellular spaces to maximize pro-inflammatory responses and mechanisms of bacterial invasion.

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Available from: Hai Ning Shi, Oct 08, 2014
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    • "In keeping with this premise, we discovered that many T3SEs from S. Typhimurium harbour a functional caspase-3 cleavage site uniquely positioned at the junction separating their distinct functional domains, thereby producing two independently functional proteins (Srikanth et al., 2010). Salmonella invasion protein A (SipA), is a bifunctional molecule with an actin-binding function of SipA is localized to a C-terminal fragment (Lilic et al., 2003) while the N-terminal fragment triggers signal transduction cascades that promote polymorphonuclear leukocyte migration (Lee et al., 2000; Wall et al., 2007). SipA also harbours a functionally active caspase-3 motif that is precisely located at the junction separating the two functional domains of this protein (Srikanth et al., 2010). "
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    Cellular Microbiology 09/2014; 16(12). DOI:10.1111/cmi.12368 · 4.92 Impact Factor
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    • "Phosphatidic acid is then converted to diacylglycerol (DAG), which recruits protein kinase C-α (PKC-α) to the apical membrane (Figure 2). PKC-α, in addition to an ERM protein ezrin, modulate the localization of MRP2 to the apical membrane of epithelial cells, thereby allowing the secretion of HXA3 into the lumen and production of the chemattractant gradient that induces neutrophil transmigration (Figure 2) (72, 74, 75). "
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    Frontiers in Immunology 07/2014; 5:311. DOI:10.3389/fimmu.2014.00311
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    • "Cell lysates were prepared post-infection by removing supernatants and scraping off cells in lysis buffer consisting of 2% Triton X-100 in phosphate buffered saline (PBS) at pH 7.5. In addition T84 cell lysates were passed 3 times through a 22-gauge syringe as previously described [30]. Protease inhibitor (Complete Mini, Roche) was added to PBS except where caspase-3 activity was monitored as this inhibited caspase-3 protease activity. "
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