scholarly journals Epithelial Cells Augment Barrier Function via Activation of the Toll-Like Receptor 2/Phosphatidylinositol 3-Kinase Pathway upon Recognition of Salmonella enterica Serovar Typhimurium Curli Fibrils in the Gut

2012 ◽  
Vol 81 (2) ◽  
pp. 478-486 ◽  
Author(s):  
Gertrude O. Oppong ◽  
Glenn J. Rapsinski ◽  
Tiffanny N. Newman ◽  
Jessalyn H. Nishimori ◽  
Steven G. Biesecker ◽  
...  
Keyword(s):  
Bacterial Translocation ◽  
Intestinal Epithelium ◽  
Salmonella Enterica ◽  
Intestinal Epithelial ◽  
Toll Like Receptor ◽  
Wild Type ◽  
Phosphatidylinositol 3 Kinase ◽  
Serovar Typhimurium ◽  
Toll Like Receptor 2 ◽  
Phosphatidylinositol 3

ABSTRACTCurli fibrils, the best-characterized functional bacterial amyloids, are an important component of enterobacterial biofilms. We have previously shown that curli fibrils are recognized by the Toll-like receptor 2 (TLR2)/TLR1 heterodimer complex. Utilizing polarized T-84 cells, an intestinal epithelial cell line derived from colon carcinoma grown on semipermeable tissue culture inserts, we determined that infection with aSalmonella entericaserovar TyphimuriumcsgBAmutant, which does not express curli, resulted in an increase in intestinal barrier permeability and an increase in bacterial translocation compared to infection with curliated wild-typeS. Typhimurium. When the TLR2 downstream signaling molecule phosphatidylinositol 3-kinase (PI3K) was blocked using wortmannin or LY294002, the difference in disruption of the intestinal epithelium and bacterial translocation was no longer observed. Additionally, disruption of polarized T-84 cells treated basolaterally with the TLR5 ligand flagellin was prevented when the polarized cells were simultaneously treated with the synthetic TLR2/TLR1 ligand Pam3CSK4or with purified curli fibrils in the apical compartment. Similar toin vitroobservations, C57BL/6 mice infected with thecsgBAmutant suffered increased disruption of the intestinal epithelium and therefore greater dissemination of the bacteria to the mesenteric lymph nodes than mice infected with wild-typeS. Typhimurium. The differences in disruption of the intestinal epithelium and bacterial dissemination in the mice infected withcsgBAmutant or wild-typeS. Typhimurium were not apparent in TLR2-deficient mice. Overall, these studies report for the first time that activation of the TLR2/PI3K pathway by microbial amyloids plays a critical role in regulating the intestinal epithelial barrier as well as monitoring bacterial translocation during infection.

scholarly journals Toll-Like Receptor Expression in C3H/HeN and C3H/HeJ Mice during Salmonella enterica Serovar Typhimurium Infection

2003 ◽  
Vol 71 (11) ◽  
pp. 6653-6657 ◽  
Author(s):  
Sabine Tötemeyer ◽  
Neil Foster ◽  
Pete Kaiser ◽  
Duncan J. Maskell ◽  
Clare E. Bryant
Keyword(s):  
Mrna Expression ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Receptor Expression ◽  
Toll Like Receptor ◽  
Wild Type ◽  
Serovar Typhimurium ◽  
Toll Like Receptor 2

ABSTRACT Here, we have investigated the mRNA expression of Toll-like receptor 2 (TLR-2), TLR-4, and MD-2 in spleens and livers of C3H/HeN mice (carrying wild-type TLR-4) and C3H/HeJ mice (carrying mutated TLR-4) in response to Salmonella infection. During Salmonella infections, TLR-4 is activated, leading to increased TLR-2 and decreased TLR-4 expression.

scholarly journals Salmonella entericaserovar Typhimurium regulates intercellular junction proteins and facilitates transepithelial neutrophil and bacterial passage

2007 ◽  
Vol 293 (1) ◽  
pp. G178-G187 ◽  
Author(s):  
Henrik Köhler ◽  
Takanori Sakaguchi ◽  
Bryan P. Hurley ◽  
Benjamin J. Kase ◽  
Hans-Christian Reinecker ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Bacterial Translocation ◽  
Intestinal Epithelium ◽  
Intestinal Barrier ◽  
Fold Increase ◽  
Molecular Composition ◽  
Junctional Complex ◽  
Intestinal Epithelial ◽  
Serovar Typhimurium ◽  
Triton X

The establishment of tight junctions (TJ) between columnar epithelial cells defines the functional barrier, which enteroinvasive pathogens have to overcome. Salmonella enterica serovar Typhimurium ( S. typhimurium) directly invades intestinal epithelial cells but it is not well understood how the pathogen is able to overcome the intestinal barrier and gains access to the circulation. Therefore, we sought to determine whether infection with S. typhimurium could regulate the molecular composition of the TJ and, if so, whether these modifications would influence bacterial translocation and polymorphonuclear leukocyte (PMN) movement across model intestinal epithelium. We found that infection of a model intestinal epithelium with S. typhimurium over 2 h resulted in an ∼80% loss of transepithelial electrical resistance. Western blot analysis of epithelial cell lysates demonstrated that S. typhimurium regulated the distribution of the TJ complex proteins claudin-1, zonula occludens (ZO)-2, and E-cadherin in Triton X-100-soluble and insoluble fractions. In addition, S. typhimurium was specifically able to dephosphorylate occludin and degrade ZO-1. This TJ alteration in the epithelial monolayer resulted in 10-fold increase in bacterial translocation and a 75% increase in N-formylmethionin-leucyl-phenyalanine-induced PMN transepithelial migration. Our data demonstrate that infection with S. typhimurium is associated with the rapid targeting of the tight junctional complex and loss of barrier function. This results in enhanced bacterial translocation and initiation of PMN migration across the intestinal barrier. Therefore, the ability to regulate the molecular composition of TJs facilitates the pathogenicity of S. typhimurium by aiding its uptake and distribution within the host.

scholarly journals Invasion Genes Are Not Required for Salmonella enterica Serovar Typhimurium To Breach the Intestinal Epithelium: Evidence That Salmonella Pathogenicity Island 1 Has Alternative Functions during Infection

2000 ◽  
Vol 68 (9) ◽  
pp. 5050-5055 ◽  
Author(s):  
Rose Ann Murray ◽  
Catherine A. Lee
Keyword(s):  
Intestinal Epithelium ◽  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Bacterial Colonization ◽  
Intestinal Barrier ◽  
Pathogenicity Island ◽  
Bacterial Invasion ◽  
Wild Type ◽  
Serovar Typhimurium

ABSTRACT Salmonella enterica serovar Typhimurium invasion genes are necessary for bacterial invasion of intestinal epithelial cells and are thought to allow salmonellae to enter and cross the intestinal epithelium during infection. Many invasion genes are encoded on Salmonella pathogenicity island 1 (SPI1), and their expression is activated by HilA, a transcription factor also encoded on SPI1. We have studied the role ofSalmonella invasion genes during infection of mice following intragastric inoculation. We have found that strains containing a mutation in hilA orinvG were recovered from the intestinal contents, intestinal tissues, and systemic tissues at a lower frequency than their parental wild-type strain. In contrast, a strain in which SPI1 is deleted was recovered from infected mice at a frequency similar to that of its parental wild-type strain. The ΔSPI1 phenotype indicates that S. enterica does not require invasion genes to cross the intestinal epithelium and infect systemic tissues. This result has forced us to reconsider the long-held belief that invasion genes directly mediate bacterial infection of the intestinal mucosa and traversion of the intestinal barrier during infection. Instead, our results suggest that hilA is required for bacterial colonization of the host intestine. The seemingly contradictory phenotype of the ΔSPI1 mutant suggests that deletion of another gene(s) encoded on SPI1 suppresses thehilA mutant defect. We propose a model for S. enterica pathogenesis in which hilA and invasion genes are required for salmonellae to overcome a host clearance response elicited by another SPI1 gene product(s).

scholarly journals Genetic Determinants of Salmonella enterica Serovar Typhimurium Proliferation in the Cytosol of Epithelial Cells

2016 ◽  
Vol 84 (12) ◽  
pp. 3517-3526 ◽  
Author(s):  
Marie Wrande ◽  
Helene Andrews-Polymenis ◽  
Donna J. Twedt ◽  
Olivia Steele-Mortimer ◽  
Steffen Porwollik ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Salmonella Enterica ◽  
Chloroquine Resistance ◽  
Intestinal Epithelial ◽  
Wild Type ◽  
Genetic Determinants ◽  
Gastrointestinal Infections ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Infectious Cycle

Intestinal epithelial cells provide an important colonization niche forSalmonella entericaserovar Typhimurium during gastrointestinal infections. In infected epithelial cells, a subpopulation ofS. Typhimurium bacteria damage their internalization vacuole, leading to escape from theSalmonella-containing vacuole (SCV) and extensive proliferation in the cytosol. Little is known about the bacterial determinants of nascent SCV lysis and subsequent survival and replication ofSalmonellain the cytosol. To pinpointS. Typhimurium virulence factors responsible for these steps in the intracellular infectious cycle, we screened aS. Typhimurium multigene deletion library in Caco-2 C2Bbe1 and HeLa epithelial cells for mutants that had an altered proportion of cytosolic bacteria compared to the wild type. We used a gentamicin protection assay in combination with a chloroquine resistance assay to quantify total and cytosolic bacteria, respectively, for each strain. Mutants of threeS. Typhimurium genes,STM1461(ydgT),STM2829(recA), andSTM3952(corA), had reduced cytosolic proliferation compared to wild-type bacteria, and one gene,STM2120(asmA), displayed increased cytosolic replication. None of the mutants were affected for lysis of the nascent SCV or vacuolar replication in epithelial cells, indicating that these genes are specifically required for survival and proliferation ofS. Typhimurium in the epithelial cell cytosol. These are the first genes identified to contribute to this step of theS. Typhimurium infectious cycle.

scholarly journals A network of Rab GTPases controls phagosome maturation and is modulated by Salmonella enterica serovar Typhimurium

2007 ◽  
Vol 176 (3) ◽  
pp. 263-268 ◽  
Author(s):  
Adam C. Smith ◽  
Won Do Heo ◽  
Virginie Braun ◽  
Xiuju Jiang ◽  
Chloe Macrae ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Dominant Negative ◽  
Rab Gtpases ◽  
Wild Type ◽  
Intracellular Growth ◽  
Non Invasive ◽  
Serovar Typhimurium ◽  
Guanosine Triphosphatase ◽  
Kinetics Of

Members of the Rab guanosine triphosphatase (GTPase) family are key regulators of membrane traffic. Here we examined the association of 48 Rabs with model phagosomes containing a non-invasive mutant of Salmonella enterica serovar Typhimurium (S. Typhimurium). This mutant traffics to lysosomes and allowed us to determine which Rabs localize to a maturing phagosome. In total, 18 Rabs associated with maturing phagosomes, each with its own kinetics of association. Dominant-negative mutants of Rab23 and 35 inhibited phagosome–lysosome fusion. A large number of Rab GTPases localized to wild-type Salmonella-containing vacuoles (SCVs), which do not fuse with lysosomes. However, some Rabs (8B, 13, 23, 32, and 35) were excluded from wild-type SCVs whereas others (5A, 5B, 5C, 7A, 11A, and 11B) were enriched on this compartment. Our studies demonstrate that a complex network of Rab GTPases controls endocytic progression to lysosomes and that this is modulated by S. Typhimurium to allow its intracellular growth.

scholarly journals Dominant missense mutations in a novel yeast protein related to mammalian phosphatidylinositol 3-kinase and VPS34 abrogate rapamycin cytotoxicity.

1993 ◽  
Vol 13 (10) ◽  
pp. 6012-6023 ◽  
Author(s):  
R Cafferkey ◽  
P R Young ◽  
M M McLaughlin ◽  
D J Bergsma ◽  
Y Koltin ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Dna Sequence ◽  
Leucine Zipper ◽  
Sequence Similarity ◽  
Missense Mutations ◽  
Wild Type ◽  
Phosphatidylinositol 3 Kinase ◽  
Haploid Strain ◽  
Diploid Cells ◽  
Phosphatidylinositol 3

Rapamycin is a macrolide antifungal agent that exhibits potent immunosuppressive properties. In Saccharomyces cerevisiae, rapamycin sensitivity is mediated by a specific cytoplasmic receptor which is a homolog of human FKBP12 (hFKBP12). Deletion of the gene for yeast FKBP12 (RBP1) results in recessive drug resistance, and expression of hFKBP12 restores rapamycin sensitivity. These data support the idea that FKBP12 and rapamycin form a toxic complex that corrupts the function of other cellular proteins. To identify such proteins, we isolated dominant rapamycin-resistant mutants both in wild-type haploid and diploid cells and in haploid rbp1::URA3 cells engineered to express hFKBP12. Genetic analysis indicated that the dominant mutations are nonallelic to mutations in RBP1 and define two genes, designated DRR1 and DRR2 (for dominant rapamycin resistance). Mutant copies of DRR1 and DRR2 were cloned from genomic YCp50 libraries by their ability to confer drug resistance in wild-type cells. DNA sequence analysis of a mutant drr1 allele revealed a long open reading frame predicting a novel 2470-amino-acid protein with several motifs suggesting an involvement in intracellular signal transduction, including a leucine zipper near the N terminus, two putative DNA-binding sequences, and a domain that exhibits significant sequence similarity to the 110-kDa catalytic subunit of both yeast (VPS34) and bovine phosphatidylinositol 3-kinases. Genomic disruption of DRR1 in a mutant haploid strain restored drug sensitivity and demonstrated that the gene encodes a nonessential function. DNA sequence comparison of seven independent drr1dom alleles identified single base pair substitutions in the same codon within the phosphatidylinositol 3-kinase domain, resulting in a change of Ser-1972 to Arg or Asn. We conclude either that DRR1 (alone or in combination with DRR2) acts as a target of FKBP12-rapamycin complexes or that a missense mutation in DRR1 allows it to compensate for the function of the normal drug target.

Schizosaccharomyces pombe Vps34p, a phosphatidylinositol-specific PI 3-kinase essential for normal cell growth and vacuole morphology

1995 ◽  
Vol 108 (12) ◽  
pp. 3745-3756 ◽  
Author(s):  
K. Takegawa ◽  
D.B. DeWald ◽  
S.D. Emr
Keyword(s):  
Amino Acid ◽  
Schizosaccharomyces Pombe ◽  
Mammalian Cells ◽  
Membrane Fraction ◽  
Kinase Activity ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Phosphatidylinositol 3 Kinase ◽  
Acid Protein ◽  
Phosphatidylinositol 3

We have cloned the gene, vps34+, from the fission yeast Schizosaccharomyces pombe which encodes an 801 amino acid protein with phosphatidylinositol 3-kinase activity. The S. pombe Vps34 protein shares 43% amino acid sequence identity with the Saccharomyces cerevisiae Vps34 protein and 28% identity with the p110 catalytic subunit of the mammalian phosphatidylinositol 3-kinase. When the vps34+ gene is disrupted, S.pombe strains are temperature-sensitive for growth and the mutant cells contain enlarged vacuoles. Furthermore, while wild-type strains exhibit substantial levels of phosphatidylinositol 3-kinase activity, this activity is not detected in the vps34 delta strain. S.pombe Vps34p-specific antiserum detects a single protein in cells of -90 kDa that fractionates almost exclusively with the crude membrane fraction. Phosphatidylinositol 3-kinase activity also is localized mainly in the membrane fraction of wild-type cells. Immunoisolated Vps34p specifically phosphorylates phosphatidylinositol on the D-3 position of the inositol ring to yield phosphatidylinositol(3)phosphate. but does not utilize phosphatidylinositol(4)phosphate or phosphatidylinositol(4,5)bisphosphate as substrates. In addition, when compared to the mammalian p110 phosphatidylinositol 3-kinase, S. pombe Vps34p is relatively insensitive to the inhibitors wortmannin and LY294002. Together, these results indicate that S. pombe Vps34 is more similar to the phosphatidylinositol-specific 3-kinase, Vps34p from S. cerevisiae, and is distinct from the p110/p85 and G protein-coupled phosphatidylinositol 3-kinases from mammalian cells. These data are discussed in relation to the possible role of Vps34p in vesicle-mediated protein sorting to the S. pombe vacuole.

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