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Mezerova K, Raclavsky V, Stary L. Which bacterial toxins are worthy of validation as markers in colorectal cancer screening? A critical review. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2021; 166:1-11. [PMID: 34747413 DOI: 10.5507/bp.2021.054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 08/25/2021] [Indexed: 12/21/2022] Open
Abstract
Appropriate screening of early asymptomatic cases can reduce the disease burden and mortality rate of sporadic colorectal cancer (CRC) significantly. Currently, fecal occult blood testing (FOBT) is able to detect up to 80% of asymptomatic cases in the population aged 50+. Therefore, there is still a demand for new screening tests that would complement FOBT, mainly by detecting at least a part of the FOBT-negative CRC and adenoma cases, or possibly by identifying person at increased risk of sporadic CRC in order to offer them tailored follow-up. Among the potential markers studied, our knowledge has advanced at most in toxigenic gram-negative bacteria. In this review, we assess their potential critically and recommend those best suited for prospective evaluation of their true ability to increase the sensitivity of FOBT when combined during general population screening. In our opinion, colibactin and Bacteroides fragilis toxin are the best candidates, possibly complemented by the cytotoxic necrotizing factor (CNF).
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Affiliation(s)
- Kristina Mezerova
- Department of Microbiology, Faculty of Medicine & Dentistry, Palacky University Olomouc, Czech Republic
| | - Vladislav Raclavsky
- Department of Microbiology, Faculty of Medicine & Dentistry, Palacky University Olomouc, Czech Republic
| | - Lubomir Stary
- Department of Surgery I, University Hospital Olomouc, Czech Republic
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2
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Pathogenesis of human enterovirulent bacteria: lessons from cultured, fully differentiated human colon cancer cell lines. Microbiol Mol Biol Rev 2014; 77:380-439. [PMID: 24006470 DOI: 10.1128/mmbr.00064-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hosts are protected from attack by potentially harmful enteric microorganisms, viruses, and parasites by the polarized fully differentiated epithelial cells that make up the epithelium, providing a physical and functional barrier. Enterovirulent bacteria interact with the epithelial polarized cells lining the intestinal barrier, and some invade the cells. A better understanding of the cross talk between enterovirulent bacteria and the polarized intestinal cells has resulted in the identification of essential enterovirulent bacterial structures and virulence gene products playing pivotal roles in pathogenesis. Cultured animal cell lines and cultured human nonintestinal, undifferentiated epithelial cells have been extensively used for understanding the mechanisms by which some human enterovirulent bacteria induce intestinal disorders. Human colon carcinoma cell lines which are able to express in culture the functional and structural characteristics of mature enterocytes and goblet cells have been established, mimicking structurally and functionally an intestinal epithelial barrier. Moreover, Caco-2-derived M-like cells have been established, mimicking the bacterial capture property of M cells of Peyer's patches. This review intends to analyze the cellular and molecular mechanisms of pathogenesis of human enterovirulent bacteria observed in infected cultured human colon carcinoma enterocyte-like HT-29 subpopulations, enterocyte-like Caco-2 and clone cells, the colonic T84 cell line, HT-29 mucus-secreting cell subpopulations, and Caco-2-derived M-like cells, including cell association, cell entry, intracellular lifestyle, structural lesions at the brush border, functional lesions in enterocytes and goblet cells, functional and structural lesions at the junctional domain, and host cellular defense responses.
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3
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Srikhanta YN, Hocking DM, Wakefield MJ, Higginson E, Robins-Browne RM, Yang J, Tauschek M. Control of bacterial virulence by the RalR regulator of the rabbit-specific enteropathogenic Escherichia coli strain E22. Infect Immun 2013; 81:4232-43. [PMID: 24002063 PMCID: PMC3811808 DOI: 10.1128/iai.00710-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 08/24/2013] [Indexed: 11/20/2022] Open
Abstract
Atypical enteropathogenic Escherichia coli (aEPEC) causes endemic diarrhea, diarrheal outbreaks, and persistent diarrhea in humans, but the mechanism by which aEPEC causes disease is incompletely understood. Virulence regulators and their associated regulons, which often include adhesins, play key roles in the expression of virulence factors in enteric pathogenic bacteria. In this study we identified a transcriptional regulator, RalR, in the rabbit-specific aEPEC strain, E22 (O103:H2) and examined its involvement in the regulation of virulence. Microarray analysis and quantitative real-time reverse transcription-PCR demonstrated that RalR enhances the expression of a number of genes encoding virulence-associated factors, including the Ral fimbria, the Aap dispersin, and its associated transport system, and downregulates several housekeeping genes, including fliC. These observations were confirmed by proteomic analysis of secreted and heat-extracted surface-associated proteins and by adherence and motility assays. To investigate the mechanism of RalR-mediated activation, we focused on its most highly upregulated target operons, ralCDEFGHI and aap. By using primer extension, electrophoretic mobility shift assay, and mutational analysis, we identified the promoter and operator sequences for these two operons. By employing promoter-lacZ reporter systems, we demonstrated that RalR activates the expression of its target genes by binding to one or more 8-bp palindromic sequences (with the consensus of TGTGCACA) located immediately upstream of the promoter core regions. Importantly, we also demonstrated that RalR is essential for virulence since infection of rabbits with E22 carrying a knockout mutation in the ralR gene completely abolished its ability to cause disease.
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Affiliation(s)
- Yogitha N. Srikhanta
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Dianna M. Hocking
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Matthew J. Wakefield
- Bioinformatics Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Genetics, The University of Melbourne, Victoria, Australia
| | - Ellen Higginson
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Roy M. Robins-Browne
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Ji Yang
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Marija Tauschek
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
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Salazar-Gonzalez H, Navarro-Garcia F. Intimate adherence by enteropathogenic Escherichia coli modulates TLR5 localization and proinflammatory host response in intestinal epithelial cells. Scand J Immunol 2011; 73:268-83. [PMID: 21204905 DOI: 10.1111/j.1365-3083.2011.02507.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Enteropathogenic Escherichia coli (EPEC) causes diarrhoeal disease by altering enterocyte physiology and producing mucosal inflammation. Many details concerning the host response against EPEC remain unknown. We evaluated the role of EPEC virulence factors on the inflammatory response through an analysis of bacterial recognition, cell signalling, and cytokine production using an in vitro epithelial cell infection model. Interestingly, we found that EPEC infection recruits Toll-like receptor 5 (TLR5) to the cell surface. We confirmed that type 3 secretion system (T3SS) and flagellin (FliC) are necessary for efficient extracellular regulated kinases 1 and 2 (ERK1/2) activation and found that intimin could down-regulate this pathway. Besides flagellin, intimin was required to keep nuclear factor kappa B (NF-κB) activated during infection. EPEC infection activated tumour necrosis factor alpha (TNF-α) production and induced interleukin (IL)-1β and IL-8 release. Virulence factors such as intimin, T3SS, EspA and fliC were required for IL-1β secretion, whereas intimin and T3SS participated in IL-8 release. Flagellin was essential for late secretion of TNF-α and IL-8 and intimin stimulated cytokine secretion. Initial adherence limited TNF-α release, whereas late attachment sustained TNF-α secretion. We conclude that intimin modulates TLR5 activation and intimate adherence alters the proinflammatory response.
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Affiliation(s)
- H Salazar-Gonzalez
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), México DF, México
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5
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Taieb F, Nougayrède JP, Oswald E. Cycle inhibiting factors (cifs): cyclomodulins that usurp the ubiquitin-dependent degradation pathway of host cells. Toxins (Basel) 2011; 3:356-68. [PMID: 22069713 PMCID: PMC3202828 DOI: 10.3390/toxins3040356] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 03/16/2011] [Accepted: 03/16/2011] [Indexed: 11/16/2022] Open
Abstract
Cycle inhibiting factors (Cifs) are type III secreted effectors produced by diverse pathogenic bacteria. Cifs are "cyclomodulins" that inhibit the eukaryotic host cell cycle and also hijack other key cellular processes such as those controlling the actin network and apoptosis. This review summarizes current knowledge on Cif since its first characterization in enteropathogenic Escherichia coli, the identification of several xenologues in distant pathogenic bacteria, to its structure elucidation and the recent deciphering of its mode of action. Cif impairs the host ubiquitin proteasome system through deamidation of ubiquitin or the ubiquitin-like protein NEDD8 that regulates Cullin-Ring-ubiquitin Ligase (CRL) complexes. The hijacking of the ubiquitin-dependent degradation pathway of host cells results in the modulation of various cellular functions such as epithelium renewal, apoptosis and immune response. Cif is therefore a powerful weapon in the continuous arm race that characterizes host-bacteria interactions.
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Affiliation(s)
- Frédéric Taieb
- INRA, USC Molecular and Cellular Pathogenesis of Escherichia coli Infections, Toulouse, F-31300, France; (J.-P.N.); (E.O.)
- Inserm, U1043, Toulouse, F-31300, France
- University of Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, F-31300, France
- CNRS, U5282, Toulouse, F-31300, France
- Author to whom correspondence should be addressed; ; Tel.: +33-5-6119-3286; Fax: +33-5-6119-3975
| | - Jean-Philippe Nougayrède
- INRA, USC Molecular and Cellular Pathogenesis of Escherichia coli Infections, Toulouse, F-31300, France; (J.-P.N.); (E.O.)
- Inserm, U1043, Toulouse, F-31300, France
- University of Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, F-31300, France
- CNRS, U5282, Toulouse, F-31300, France
| | - Eric Oswald
- INRA, USC Molecular and Cellular Pathogenesis of Escherichia coli Infections, Toulouse, F-31300, France; (J.-P.N.); (E.O.)
- Inserm, U1043, Toulouse, F-31300, France
- University of Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, F-31300, France
- CNRS, U5282, Toulouse, F-31300, France
- CHU Toulouse, Hôpital Purpan, Service de Bactériologie-Hygiène, Toulouse, F-31300, France
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6
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Jubelin G, Taieb F, Duda DM, Hsu Y, Samba-Louaka A, Nobe R, Penary M, Watrin C, Nougayrède JP, Schulman BA, Stebbins CE, Oswald E. Pathogenic bacteria target NEDD8-conjugated cullins to hijack host-cell signaling pathways. PLoS Pathog 2010; 6:e1001128. [PMID: 20941356 PMCID: PMC2947998 DOI: 10.1371/journal.ppat.1001128] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 09/01/2010] [Indexed: 11/22/2022] Open
Abstract
The cycle inhibiting factors (Cif), produced by pathogenic bacteria isolated from vertebrates and invertebrates, belong to a family of molecules called cyclomodulins that interfere with the eukaryotic cell cycle. Cif blocks the cell cycle at both the G1/S and G2/M transitions by inducing the stabilization of cyclin-dependent kinase inhibitors p21waf1 and p27kip1. Using yeast two-hybrid screens, we identified the ubiquitin-like protein NEDD8 as a target of Cif. Cif co-compartmentalized with NEDD8 in the host cell nucleus and induced accumulation of NEDD8-conjugated cullins. This accumulation occurred early after cell infection and correlated with that of p21 and p27. Co-immunoprecipitation revealed that Cif interacted with cullin-RING ubiquitin ligase complexes (CRLs) through binding with the neddylated forms of cullins 1, 2, 3, 4A and 4B subunits of CRL. Using an in vitro ubiquitylation assay, we demonstrate that Cif directly inhibits the neddylated CUL1-associated ubiquitin ligase activity. Consistent with this inhibition and the interaction of Cif with several neddylated cullins, we further observed that Cif modulates the cellular half-lives of various CRL targets, which might contribute to the pathogenic potential of diverse bacteria. Among the arsenal of virulence factors used by bacterial pathogens to infect and manipulate their hosts, cyclomodulins are a growing family of bacterial toxins that interfere with the eukaryotic cell-cycle. Cif is one of these cyclomodulins produced by both mammalian and invertebrate pathogenic bacteria. Cif blocks the host cell cycle by inducing the accumulation of two regulators of cell cycle progression: the cyclin-dependent kinase inhibitors p21 and p27. To decipher the mode of action of Cif, we performed yeast two-hybrid screenings. We show that Cif binds to NEDD8 and induce accumulation of neddylated cullins early after infection. Cullins are scaffold components of cullin-RING ubiquitin ligases (CRLs), which ubiquitinate proteins and target them for degradation by the 26S proteasome. We demonstrate that Cif directly inhibits the ubiquitin ligase activity of these CRLs and consequently the targeting of p21 and p27 for ubiquitin-dependent degradation. Targeting at NEDD8 represents a novel strategy for modulation of host cell functions by bacterial pathogens. By inhibiting the most prominent class of ubiquitin-ligases, Cif controls the stability of a cohort of key regulators and impinge on not only cell cycle progression but also on many cellular and biological processes such as immunity, development, transcription, and cell signaling.
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Affiliation(s)
- Grégory Jubelin
- INRA, UMR 1225, Toulouse, France
- Université de Toulouse; ENVT; UMR 1225; Toulouse, France
| | - Frédéric Taieb
- INRA, UMR 1225, Toulouse, France
- Université de Toulouse; ENVT; UMR 1225; Toulouse, France
| | - David M. Duda
- Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Department of Structural Biology, Memphis, Tennessee, United States of America
| | - Yun Hsu
- Laboratory of Structural Microbiology, Rockefeller University, New York, New York, United States of America
| | - Ascel Samba-Louaka
- INRA, UMR 1225, Toulouse, France
- Université de Toulouse; ENVT; UMR 1225; Toulouse, France
| | - Rika Nobe
- INRA, UMR 1225, Toulouse, France
- Université de Toulouse; ENVT; UMR 1225; Toulouse, France
| | - Marie Penary
- INRA, UMR 1225, Toulouse, France
- Université de Toulouse; ENVT; UMR 1225; Toulouse, France
| | - Claude Watrin
- INRA, UMR 1225, Toulouse, France
- Université de Toulouse; ENVT; UMR 1225; Toulouse, France
| | | | - Brenda A. Schulman
- Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Department of Structural Biology, Memphis, Tennessee, United States of America
| | - C. Erec Stebbins
- Laboratory of Structural Microbiology, Rockefeller University, New York, New York, United States of America
- * E-mail: (CES); (EO)
| | - Eric Oswald
- INRA, UMR 1225, Toulouse, France
- Université de Toulouse; ENVT; UMR 1225; Toulouse, France
- Université de Toulouse; UPS; Faculté de Médecine; Toulouse, France
- CHU de Toulouse; Institut Fédératif de Biologie; Laboratoire de Bactériologie-Hygiène; Toulouse, France
- * E-mail: (CES); (EO)
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7
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Samba-Louaka A, Taieb F, Nougayrède JP, Oswald E. Cif type III effector protein: a smart hijacker of the host cell cycle. Future Microbiol 2009; 4:867-77. [PMID: 19722840 DOI: 10.2217/fmb.09.60] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
During coevolution with their hosts, bacteria have developed functions that allow them to interfere with the mechanisms controlling the proliferation of eukaryotic cells. Cycle inhibiting factor (Cif) is one of these cyclomodulins, the family of bacterial effectors that interfere with the host cell cycle. Acquired early during evolution by bacteria isolated from vertebrates and invertebrates, Cif is an effector protein of type III secretion machineries. Cif blocks the host cell cycle in G1 and G2 by inducing the accumulation of the cyclin-dependent kinase inhibitors p21(waf1/cip1) and p27(kip1). The x-ray crystal structure of Cif reveals it to be a divergent member of a superfamily of enzymes including cysteine proteases and acetyltransferases. This review summarizes and discusses what we know about Cif, from the bacterial gene to the host target.
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8
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Nobe R, Nougayrède JP, Taieb F, Bardiau M, Cassart D, Navarro-Garcia F, Mainil J, Hayashi T, Oswald E. Enterohaemorrhagic Escherichia coli serogroup O111 inhibits NF-(kappa)B-dependent innate responses in a manner independent of a type III secreted OspG orthologue. MICROBIOLOGY-SGM 2009; 155:3214-3225. [PMID: 19628559 DOI: 10.1099/mic.0.030759-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Enterohaemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) inject a repertoire of effector proteins into host cells via a type III secretion system (T3SS) encoded by the locus of enterocyte effacement (LEE). OspG is an effector protein initially identified in Shigella that was shown to inhibit the host innate immune response. In this study, we found ospG homologues in EHEC (mainly of serogroup O111) and in Yersinia enterocolitica. The T3SS encoded by the LEE was able to inject these different OspG homologues into host cells. Infection of HeLa cells with EHEC O111 inhibited the NF-kappaB-dependent innate immune response via a T3SS-dependent mechanism. However, an EHEC O111 ospG mutant was still able to inhibit NF-kappaB p65 transfer to the nucleus in infected cells stimulated by tumour necrosis factor alpha (TNF-alpha). In addition, no difference in the inflammatory response was observed between wild-type EHEC O111 and the isogenic ospG mutant in the rabbit ligated intestinal loop model. These results suggest that OspG is not the sole effector protein involved in the inactivation of the host innate immune system during EHEC O111 infection.
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Affiliation(s)
- Rika Nobe
- Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.,INRA, UMR1225, ENVT, F-31076 Toulouse, France
| | - Jean-Philippe Nougayrède
- Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.,INRA, UMR1225, ENVT, F-31076 Toulouse, France
| | - Frédéric Taieb
- Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.,INRA, UMR1225, ENVT, F-31076 Toulouse, France
| | - Marjorie Bardiau
- Department of Infectious Diseases, Bacteriology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman, Liège B4000, Belgium
| | - Dominique Cassart
- Department of Morphology and Pathology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman, Liège B4000, Belgium
| | - Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados (CINVESTAV-IPN), Ap. Postal 14-740, 07000 Mexico DF, Mexico
| | - Jacques Mainil
- Department of Infectious Diseases, Bacteriology, Faculty of Veterinary Medicine, University of Liège, Sart Tilman, Liège B4000, Belgium
| | - Tetsuya Hayashi
- Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Eric Oswald
- Université de Toulouse, ENVT, UMR1225, F-31076 Toulouse, France.,INRA, UMR1225, ENVT, F-31076 Toulouse, France
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9
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Comparative analysis of the locus of enterocyte effacement and its flanking regions. Infect Immun 2009; 77:3501-13. [PMID: 19506015 DOI: 10.1128/iai.00090-09] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The attaching-and-effacing (A/E) phenotype mediated by factors derived from the locus of enterocyte effacement (LEE) is a hallmark of clinically important intestinal pathotypes of Escherichia coli, including enteropathogenic (EPEC), atypical EPEC (ATEC), and enterohemorrhagic E. coli strains. Epidemiological studies indicate that the frequency of diarrhea outbreaks caused by ATEC is increasing. Hence, it is of major importance to further characterize putative factors contributing to the pathogenicity of these strains and to gain additional insight into the plasticity and evolutionary aspects of this emerging pathotype. Here, we analyzed the two clinical ATEC isolates B6 (O26:K60) and 9812 (O128:H2) and compared the genetic organizations, flanking regions, and chromosomal insertion loci of their LEE with those of the LEE of other A/E pathogens. Our analysis shows that the core LEE is largely conserved-particularly among genes coding for the type 3 secretion system-whereas genes encoding effector proteins display a higher variability. Chromosomal insertion loci appear to be restricted to selC, pheU, and pheV. In contrast, striking differences were found between the 5'- and 3'-associated flanking regions reflecting the different histories of the various strains and also possibly indicating different lines in evolution.
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10
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Gallois M, Gidenne T, Tasca C, Caubet C, Coudert C, Milon A, Boullier S. Maternal milk contains antimicrobial factors that protect young rabbits from enteropathogenic Escherichia coli infection. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:585-92. [PMID: 17344351 PMCID: PMC1865632 DOI: 10.1128/cvi.00468-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) colibacillosis represents a major cause of lethal diarrhea in young children in developing countries. EPEC strains also infect numerous mammal species and represent a major economical problem in rabbit industry. Protection against this pathogen is a challenging goal both in humans and in other mammal species. Despite a good knowledge of the pathogenicity mechanisms of EPEC, the intrinsic and environmental factors that control the expression of EPEC virulence in mammals remain unknown. For instance, the exacerbated sensitivity of young mammals to EPEC infection is still unexplained. Our goal was to investigate if age or other factors, like milk consumption, could be determinants that trigger the disease. We used rabbits as an animal model to study the role of milk in the sensitivity to an EPEC infection. Weaned and suckling rabbits were orally inoculated with EPEC strain E22 (O103:H2:K-) at 28 days of age, and the evolution of the disease was investigated in the two groups. In addition, in order to better characterize the interactions between milk and EPEC, we determined in vitro bacterial growth and the abilities of EPEC cells to adhere to epithelial cells in the presence of milk. Our results demonstrate a protective role of milk in vivo in association with in vitro antibacterial activity. These effects are independent of the presence of specific anti-EPEC antibodies.
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Affiliation(s)
- Mélanie Gallois
- INRA, UMR 1289 TANDEM, Chemin de Borde-Rouge-Auzeville, Castanet-Tolosan, Toulouse, France
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11
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Taieb F, Nougayrède JP, Watrin C, Samba-Louaka A, Oswald E. Escherichia coli cyclomodulin Cif induces G2arrest of the host cell cycle without activation of the DNA-damage checkpoint-signalling pathway. Cell Microbiol 2006; 8:1910-21. [PMID: 16848790 DOI: 10.1111/j.1462-5822.2006.00757.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The cycle inhibiting factor (Cif) belongs to a family of bacterial toxins and effector proteins, the cyclomodulins, that deregulate the host cell cycle. Upon injection into HeLa cells by the enteropathogenic Escherichia coli (EPEC) type III secretion system, Cif induces a cytopathic effect characterized by the recruitment of focal adhesion plates and the formation of stress fibres, an irreversible cell cycle arrest at the G(2)/M transition, and sustained inhibitory phosphorylation of mitosis inducer, CDK1. Here, we report that the reference typical EPEC strain B171 produces a functional Cif and that lipid-mediated delivery of purified Cif into HeLa cells induces cell cycle arrest and actin stress fibres, implying that Cif is necessary and sufficient for these effects. EPEC infection of intestinal epithelial cells (Caco-2, IEC-6) also induces cell cycle arrest and CDK1 inhibition. The effect of Cif is strikingly similar to that of cytolethal distending toxin (CDT), which inhibits the G(2)/M transition by activating the DNA-damage checkpoint pathway. However, in contrast to CDT, Cif does not cause phosphorylation of histone H2AX, which is associated with DNA double-stranded breaks. Following EPEC infection, the checkpoint effectors ATM/ATR, Chk1 and Chk2 are not activated, the levels of the CDK-activating phosphatases Cdc25B and Cdc25C are not affected, and Cdc25C is not sequestered in host cell cytoplasm. Hence, Cif activates a DNA damage-independent signalling pathway that leads to inhibition of the G(2)/M transition.
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Affiliation(s)
- Frédéric Taieb
- UMR 1225, IHAP, INRA-ENVT, 23 Chemin des Capelles, BP 87614, 31000 Toulouse, France.
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12
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Wales AD, Woodward MJ, Pearson GR. Attaching-effacing bacteria in animals. J Comp Pathol 2005; 132:1-26. [PMID: 15629476 PMCID: PMC7118730 DOI: 10.1016/j.jcpa.2004.09.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Accepted: 09/21/2004] [Indexed: 12/24/2022]
Abstract
Enteric bacteria with a demonstrable or potential ability to form attaching-effacing lesions, so-called attaching-effacing (AE) bacteria, have been found in the intestinal tracts of a wide variety of warm-blooded animal species, including man. In some host species, for example cattle, pigs, rabbits and human beings, attaching-effacing Escherichia coli (AEEC) have an established role as enteropathogens. In other host species, AE bacteria are of less certain significance. With continuing advances in the detection and typing of AE strains, the importance of these bacteria for many hosts is likely to become clearer. The pathogenic effects of AE bacteria result from adhesion to the intestinal mucosa by a variety of mechanisms, culminating in the formation of the characteristic intimate adhesion of the AE lesion. The ability to induce AE lesions is mediated by the co-ordinated expression of some 40 bacterial genes organized within a so-called pathogenicity island, known as the "Locus for Enterocyte Effacement". It is also believed that the production of bacterial toxins, principally Vero toxins, is a significant virulence factor for some AEEC strains. Recent areas of research into AE bacteria include: the use of Citrobacter rodentium to model human AEEC disease; quorum-sensing mechanisms used by AEEC to modulate virulence gene expression; and the potential role of adhesion in the persistent colonization of the intestine by AE bacteria. This review of AE bacteria covers their molecular biology, their occurrence in various animal species, and the diagnosis, pathology and clinical aspects of animal diseases with which they are associated. Reference is made to human pathogens where appropriate. The focus is mainly on natural colonization and disease, but complementary experimental data are also included.
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Affiliation(s)
- A D Wales
- Division of Veterinary Pathology, Infection and Immunity, School of Veterinary Science, University of Bristol, Langford, Bristol BS40 5DU, UK
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13
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Ramirez K, Huerta R, Oswald E, Garcia-Tovar C, Hernandez JM, Navarro-Garcia F. Role of EspA and intimin in expression of proinflammatory cytokines from enterocytes and lymphocytes by rabbit enteropathogenic Escherichia coli-infected rabbits. Infect Immun 2005; 73:103-13. [PMID: 15618145 PMCID: PMC538993 DOI: 10.1128/iai.73.1.103-113.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) produces attaching and effacing (A/E) lesions and watery diarrhea, both of which are intimin and EspA dependent. In this work, we explored the mucosal immune response by detecting cytokine induction in rabbits with diarrhea caused by rabbit EPEC (REPEC). Orally inoculated rabbits exhibited weight loss and mucosal inflammation, developed watery diarrhea, and died (day 7). At day 6 postinoculation, animals were analyzed for the induction of proinflammatory cytokines in enterocytes. The role of lymphocyte-dependent immunity was determined through the expression of proinflammatory cytokines by lymphocytes from Peyer's patches (PP) and the spleen. EspA and intimin mutants were used to explore the role of A/E lesions in the expression of these cytokines. REPEC-infected rabbit enterocytes showed increased interleukin 1beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) mRNA expression, but that of anti-inflammatory IL-10 was increased only slightly. In contrast, intimin mutant-infected rabbits were unable to produce this proinflammatory cytokine profile but did produce a remarkable increase in IL-10 expression. Bacteria lacking EspA increased the expression of IL-8 and TNF-alpha, but that of IL-10 was increased only slightly. PP lymphocytes also produced proinflammatory cytokines, which were dependent on EspA (except for TNF-alpha) and intimin, while IL-10 was induced by EspA and intimin mutants. In contrast, spleen lymphocytes (systemic compartment) were unable to produce IL-1beta and TNF-alpha. These data show the importance of the proinflammatory cytokines secreted by enterocytes and those expressed locally by PP lymphocytes, which can activate effector mechanisms at the epithelium. Furthermore, this cytokine profile, including IL-6 and IL-1beta, which may be involved in the diarrhea produced by EPEC, depends on intimin.
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Affiliation(s)
- Karina Ramirez
- Department of Cell Biology, CINVESTAV-IPN, Ap. Postal 14-740, 07000 México City, Mexico
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14
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Viswanathan VK, Lukic S, Koutsouris A, Miao R, Muza MM, Hecht G. Cytokeratin 18 interacts with the enteropathogenic Escherichia coli secreted protein F (EspF) and is redistributed after infection. Cell Microbiol 2004; 6:987-97. [PMID: 15339273 DOI: 10.1111/j.1462-5822.2004.00416.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Enteropathogenic Escherichia coli (EPEC) pathogenesis requires the delivery of effector proteins into host cytosol by a type III secretion system. The effector protein EspF, while critical for disruption of epithelial barrier function through alteration of tight junctions, is not required for bacterial viability or attachment. Yeast two-hybrid analyses revealed host intermediate filament (IF) protein cytokeratin 18 (CK18) as an interacting partner of EspF. This was confirmed by co-immunoprecipitation of extracts from EPEC-infected epithelial cells. EPEC infection increased detergent-soluble CK18 amounts without significantly altering CK18 expression. The adaptor protein 14-3-3 binds to CK18 and modulates its solubility. EPEC infection promoted CK18/14-3-3 interactions, corresponding to the increase of CK18 in the soluble fractions. 14-3-3 also co-immunoprecipitated with EspF, suggesting that CK18, 14-3-3 and EspF may form a complex in infected cells. The 14-3-3zeta isoform was co-immunoprecipitated with CK18, suggesting the involvement of specific signalling pathways. Immunofluorescence studies revealed a dramatic alteration in the architecture of the IF network in EPEC-infected epithelial cells. IF fragmentation, evident at 2 h post infection, progressed to a collapse of this network at later time points. The secretion mutant (DeltaescN) failed to alter CK18 solubility and IF morphology, while deletion of espF partially impaired the ability of EPEC to induce CK18 modifications. These results suggest that modifications in 14-3-3 interactions and IF network, modulated by type III secreted proteins, may be an important step in EPEC pathogenesis.
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Affiliation(s)
- V K Viswanathan
- Department of Medicine, M/C 716, Section of Digestive Diseases and Nutrition, University of Illinois at Chicago, Room 718, Clinical Sciences Building, 840S. Wood Street, Chicago, IL 60612-7323, USA
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15
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Charpentier X, Oswald E. Identification of the secretion and translocation domain of the enteropathogenic and enterohemorrhagic Escherichia coli effector Cif, using TEM-1 beta-lactamase as a new fluorescence-based reporter. J Bacteriol 2004; 186:5486-95. [PMID: 15292151 PMCID: PMC490934 DOI: 10.1128/jb.186.16.5486-5495.2004] [Citation(s) in RCA: 253] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) strains are human and animal pathogens that inject effector proteins into host cells via a type III secretion system (TTSS). Cif is an effector protein which induces host cell cycle arrest and reorganization of the actin cytoskeleton. Cif is encoded by a lambdoid prophage present in most of the EPEC and EHEC strains. In this study, we analyzed the domain that targets Cif to the TTSS by using a new reporter system based on a translational fusion of the effector proteins with mature TEM-1 beta-lactamase. Translocation was detected directly in living host cells by using the fluorescent beta-lactamase substrate CCF2/AM. We show that the first 16 amino acids (aa) of Cif were necessary and sufficient to mediate translocation into the host cells. Similarly, the first 20 aa of the effector proteins Map, EspF, and Tir, which are encoded in the same region as the TTSS, mediated secretion and translocation in a type III-dependent but chaperone-independent manner. A truncated form of Cif lacking its first 20 aa was no longer secreted and translocated, but fusion with the first 20 aa of Tir, Map, or EspF restored both secretion and translocation. In addition, the chimeric proteins were fully able to trigger host cell cycle arrest and stress fiber formation. In conclusion, our results demonstrate that Cif is composed of a C-terminal effector domain and an exchangeable N-terminal translocation signal and that the TEM-1 reporter system is a convenient tool for the study of the translocation of toxins or effector proteins into host cells.
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Affiliation(s)
- Xavier Charpentier
- UMR 1225, Institut National de la Recherche Agronomique, Ecole Nationale Vétérinaire de Toulouse, 31076 Toulouse Cedex, France
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16
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Identification of the secretion and translocation domain of the enteropathogenic and enterohemorrhagic Escherichia coli effector Cif, using TEM-1 beta-lactamase as a new fluorescence-based reporter. J Bacteriol 2004. [PMID: 15292151 DOI: 10.1128/jb.186.16.5486-5495.2004]] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) strains are human and animal pathogens that inject effector proteins into host cells via a type III secretion system (TTSS). Cif is an effector protein which induces host cell cycle arrest and reorganization of the actin cytoskeleton. Cif is encoded by a lambdoid prophage present in most of the EPEC and EHEC strains. In this study, we analyzed the domain that targets Cif to the TTSS by using a new reporter system based on a translational fusion of the effector proteins with mature TEM-1 beta-lactamase. Translocation was detected directly in living host cells by using the fluorescent beta-lactamase substrate CCF2/AM. We show that the first 16 amino acids (aa) of Cif were necessary and sufficient to mediate translocation into the host cells. Similarly, the first 20 aa of the effector proteins Map, EspF, and Tir, which are encoded in the same region as the TTSS, mediated secretion and translocation in a type III-dependent but chaperone-independent manner. A truncated form of Cif lacking its first 20 aa was no longer secreted and translocated, but fusion with the first 20 aa of Tir, Map, or EspF restored both secretion and translocation. In addition, the chimeric proteins were fully able to trigger host cell cycle arrest and stress fiber formation. In conclusion, our results demonstrate that Cif is composed of a C-terminal effector domain and an exchangeable N-terminal translocation signal and that the TEM-1 reporter system is a convenient tool for the study of the translocation of toxins or effector proteins into host cells.
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17
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Marchès O, Ledger TN, Boury M, Ohara M, Tu X, Goffaux F, Mainil J, Rosenshine I, Sugai M, De Rycke J, Oswald E. Enteropathogenic and enterohaemorrhagic Escherichia coli deliver a novel effector called Cif, which blocks cell cycle G2/M transition. Mol Microbiol 2004; 50:1553-67. [PMID: 14651638 DOI: 10.1046/j.1365-2958.2003.03821.x] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Enteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli (EHEC) are closely related pathogens. Both use a type III secretion system (TTSS) encoded by the 'locus of enterocyte effacement' (LEE) to subvert and attach to epithelial cells through the injection of a repertoire of effector molecules. Here, we report the identification of a new TTSS translocated effector molecule called Cif, which blocks cell cycle G2/M transition and induces the formation of stress fibres through the recruitment of focal adhesions. Cif is not encoded by the LEE but by a lambdoid prophage present in EPEC and EHEC. A cif mutant causes localized effacement of microvilli and intimately attaches to the host cell surface, but is defective in the ability to block mitosis. When expressed in TTSS competent LEE-positive pathogens, Cif is injected into the infected epithelial cells. These cells arrested at the G2/M phase displayed accumulation of inactive phosphorylated Cdk1. In conclusion, Cif is a new member of a growing family of bacterial cyclomodulins that subvert the host eukaryotic cell cycle.
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Affiliation(s)
- Olivier Marchès
- UMR 1225, Institut National de la Recherche Agronomique-Ecole Nationale Vétérinaire de Toulouse, 23 chemin des Capelles, 31076 Toulouse Cedex, France
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18
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De Rycke J, Ducommun B. [Bacterial cyclostatin, or how do bacteria manipulate the eukaryotic cell cycle]. Med Sci (Paris) 2004; 19:1128-36. [PMID: 14648484 DOI: 10.1051/medsci/200319111128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Several bacterial proteins have been recently described that share the ability to inhibit the proliferation of cells in culture without causing early signs of cytotoxicity. Such observations suggest the existence of bacterial mechanisms of control of the eukaryotic cell cycle contributing to pathogenicity or adaptation to the host. This emerging concept of cellular microbiology is critically analyzed considering as a model the cytolethal distending toxins (CDT), a family of toxins whose mode of action on the cell cycle has been thoroughly studied over the last few years. CDTs activate a physiological G2 checkpoint in exposed cells, probably from an initial DNA alteration whose precise molecular nature has not yet been determined. Experimental data are lacking to extrapolate in vivo the antiproliferative effect of these bacterial proteins that we tentatively propose to call cyclostatins.
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Affiliation(s)
- Jean De Rycke
- Laboratoire Inra de Pathologie Infectieuse et Immunologie, BP 1 37380 Nouzilly, France.
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19
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Boullier S, Nougayrède JP, Marchès O, Tasca C, Boury M, Oswald E, De Rycke J, Milon A. Genetically engineered enteropathogenic Escherichia coli strain elicits a specific immune response and protects against a virulent challenge. Microbes Infect 2003; 5:857-67. [PMID: 12919854 DOI: 10.1016/s1286-4579(03)00175-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Enteropathogenic Escherichia coli (EPEC), a major cause of severe disease with diarrhea in infants, is also involved in weaned rabbit colibacillosis. EPEC O103 is frequent in rabbit-fattening units of Western Europe. It causes high mortality and growth retardation, leading to substantial economic losses. We report here the construction by allelic exchange of an EPEC O103 strain mutated in espB and tir, two essential virulence genes. Upon live oral administration to weaned rabbits, the E22DeltaTir/EspB mutant strain efficiently colonized the intestinal tract without any adverse consequences. The rabbits were challenged with the highly pathogenic parental strain E22. The mutant provided complete protection to rabbits and total resistance to intestinal colonization by E22. In addition, E22DeltaTir/EspB strain induced a specific humoral response against the bacterial adhesin AF/R2. These Abs prevent bacterial attachment to epithelial cells in vitro. These results open the way for the development of an efficient vaccine strategy against rabbit EPEC infections.
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Affiliation(s)
- Séverine Boullier
- UMR 1225, Institut National de la Recherche Agronomique, Ecole Nationale Vétérinaire de Toulouse, 31076 Toulouse cedex 3, France.
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20
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Nougayrède JP, Boury M, Tasca C, Marchès O, Milon A, Oswald E, De Rycke J. Type III secretion-dependent cell cycle block caused in HeLa cells by enteropathogenic Escherichia coli O103. Infect Immun 2001; 69:6785-95. [PMID: 11598051 PMCID: PMC100056 DOI: 10.1128/iai.69.11.6785-6795.2001] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rabbit enteropathogenic Escherichia coli (EPEC) O103 induces in HeLa cells an irreversible cytopathic effect characterized by the recruitment of focal adhesions, formation of stress fibers, and inhibition of cell proliferation. We have characterized the modalities of the proliferation arrest and investigated its underlying mechanisms. We found that HeLa cells that were exposed to the rabbit EPEC O103 strain E22 progressively accumulated at 4C DNA content and did not enter mitosis. A significant proportion of the cells were able to reinitiate DNA synthesis without division, leading to 8C DNA content. This cell cycle inhibition by E22 was abrogated in mutants lacking EspA, -B, and -D and was restored by transcomplementation. In contrast, intimin and Tir mutants retained the antiproliferative effect. The cell cycle arrest was not a direct consequence of the formation of stress fibers, since their disruption by toxins during exposure to E22 did not reverse the cell cycle inhibition. Likewise, the cell cycle arrest was not dependent on the early tyrosine dephosphorylation events triggered by E22 in the cells. Two key partner effectors controlling entry into mitosis were also investigated: cyclin B1 and the associated cyclin-dependent kinase 1 (Cdk1). Whereas cyclin B1 was not detectably affected in E22-exposed cells, Cdk1 was maintained in a tyrosine-phosphorylated inactive state and lost its affinity for p13(suc1)-agarose beads. This shows that Cdk1 is implicated in the G2/M arrest caused by EPEC strain E22.
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Affiliation(s)
- J P Nougayrède
- UMR 960 de Microbiologie Moléculaire, Institut National de la Recherche Agronomique-Ecole Nationale Vétérinaire de Toulouse, 31076 Toulouse Cedex, France.
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21
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Zhu C, Agin TS, Elliott SJ, Johnson LA, Thate TE, Kaper JB, Boedeker EC. Complete nucleotide sequence and analysis of the locus of enterocyte Effacement from rabbit diarrheagenic Escherichia coli RDEC-1. Infect Immun 2001; 69:2107-15. [PMID: 11254564 PMCID: PMC98136 DOI: 10.1128/iai.69.4.2107-2115.2001] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2000] [Accepted: 12/01/2000] [Indexed: 12/23/2022] Open
Abstract
The pathogenicity island termed the locus of enterocyte effacement (LEE) is found in diverse attaching and effacing pathogens associated with diarrhea in humans and other animal species. To explore the relation of variation in LEE sequences to host specificity and genetic lineage, we determined the nucleotide sequence of the LEE region from a rabbit diarrheagenic Escherichia coli strain RDEC-1 (O15:H-) and compared it with those from human enteropathogenic E. coli (EPEC, O127:H6) and enterohemorrhagic E. coli (EHEC, O157:H7) strains. Differing from EPEC and EHEC LEEs, the RDEC-1 LEE is not inserted at selC and is flanked by an IS2 element and the lifA toxin gene. The RDEC-1 LEE contains a core region of 40 open reading frames, all of which are shared with the LEE of EPEC and EHEC. orf3 and the ERIC (enteric repetitive intergenic consensus) sequence present in the LEEs of EHEC and EPEC are absent from the RDEC-1 LEE. The predicted promoters of LEE1, LEE2, LEE3, tir, and LEE4 operons are highly conserved among the LEEs, although the upstream regions varied considerably for tir and the crucial LEE1 promoter, suggesting differences in regulation. Among the shared genes, high homology (>95% identity) between the RDEC-1 and the EPEC and EHEC LEEs at the predicted amino acid level was observed for the components of the type III secretion apparatus, the Ces chaperones, and the Ler regulator. In contrast, more divergence (66 to 88% identity) was observed in genes encoding proteins involved in host interaction, such as intimin (Eae) and the secreted proteins (Tir and Esps). A comparison of the highly variable genes from RDEC-1 with those from a number of attaching and effacing pathogens infecting different species and of different evolutionary lineages was performed. Although RDEC-1 diverges from some human-infecting EPEC and EHEC, most of the variation observed appeared to be due to evolutionary lineage rather than host specificity. Therefore, much of the observed hypervariability in genes involved in pathogenesis may not represent specific adaptation to different host species.
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Affiliation(s)
- C Zhu
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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Goffaux F, China B, Janssen L, Mainil J. Genotypic characterization of enteropathogenic Escherichia coli (EPEC) isolated in Belgium from dogs and cats. Res Microbiol 2000; 151:865-71. [PMID: 11191812 DOI: 10.1016/s0923-2508(00)01153-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) are isolated from man and farm animals but also from dogs and cats. They produce typical histological lesions called 'attaching and effacing' lesions. Both plasmid and chromosomal elements are involved in the pathogenesis of EPEC infection. The presence of these genetic elements was investigated in 14 dog and three cat EPEC isolates. A bfpA-related gene was detected in five of the 17 isolates in association with high molecular weight plasmids, and a locus of enterocyte effacement (LEE) was present in all isolates. The LEE was inserted in the selC region in only 12% of the isolates. The eae, tir, espA and espB genes were analyzed by multiplex PCR. The results indicated the presence of those genes in the tested isolates with heterogeneity in the gene subtypes present: eae gamma-tir alpha-espA alpha-espB alpha (65%), eae beta-tir beta-espA beta-espB beta (29%), eae alpha-tir alpha-espA alpha-espB alpha (6%). Moreover, the espD gene was also present in dog and cat EPEC. The DEPEC and CEPEC form a heterogeneous group and five of them are closely related to human EPEC.
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Affiliation(s)
- F Goffaux
- Laboratory of Bacteriology, Faculty of Veterinary Medicine, University of Liège, Belgium.
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23
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An H, Fairbrother JM, Désautels C, Mabrouk T, Dugourd D, Dezfulian H, Harel J. Presence of the LEE (locus of enterocyte effacement) in pig attaching and effacing Escherichia coli and characterization of eae, espA, espB and espD genes of PEPEC (pig EPEC) strain 1390. Microb Pathog 2000; 28:291-300. [PMID: 10799279 DOI: 10.1006/mpat.1999.0346] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In the present study, attaching and effacing Escherichia coli (AEEC) O45 isolates from post-weaning pigs with diarrhoea were examined for the presence of the LEE (locus of enterocyte effacement) using various DNA probes derived from the LEE of human enteropathogenic E. coli (EPEC) strain E2348/69. The LEE fragment was conserved among the eae -positive pig isolates. The attaching and effacing activity of PEPEC (pig EPEC) O45 isolates is highly correlated with the presence of the LEE. Nevertheless, for some PEPEC isolates, the insertion site of the LEE is different or has diverged during evolution. The presence of the LEE fragment in PEPEC isolates provides further evidence that the LEE region is conserved among AEEC of different animal origins. In addition, the nucleotide sequence of the region containing the eae gene and esp genes of a pig AEEC isolate, strain 1390, was determined. Among examined Eae proteins, Eae of strain 1390 showed the highest similarity with Eae belonging to the beta intimin group such as the Eae of rabbit AEEC. Moreover, all pig strains that produced attaching and effacing lesions in piglets and pig ileal explants belonged to the beta intimin group. The deduced amino acid sequences of the EspA, EspB and EspD proteins of strain 1390 showed particularly strong homology to those of AEEC strains presenting a beta intimin allele. Thus, pig AEEC possess the LEE sequences, and for the strain 1390, sequences of the eae and esp regions are related to those of other AEEC, in particular, strains presenting a beta intimin allele, such as the rabbit AEEC.
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Affiliation(s)
- H An
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Université de Montréal, C.P. 5000, Saint-Hyacinthe, Québec, J2S 7C6, Canada
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Marchès O, Nougayrède JP, Boullier S, Mainil J, Charlier G, Raymond I, Pohl P, Boury M, De Rycke J, Milon A, Oswald E. Role of tir and intimin in the virulence of rabbit enteropathogenic Escherichia coli serotype O103:H2. Infect Immun 2000; 68:2171-82. [PMID: 10722617 PMCID: PMC97401 DOI: 10.1128/iai.68.4.2171-2182.2000] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Attaching and effacing (A/E) rabbit enteropathogenic Escherichia coli (REPEC) strains belonging to serogroup O103 are an important cause of diarrhea in weaned rabbits. Like human EPEC strains, they possess the locus of enterocyte effacement clustering the genes involved in the formation of the A/E lesions. In addition, pathogenic REPEC O103 strains produce an Esp-dependent but Eae (intimin)-independent alteration of the host cell cytoskeleton characterized by the formation of focal adhesion complexes and the reorganization of the actin cytoskeleton into bundles of stress fibers. To investigate the role of intimin and its translocated coreceptor (Tir) in the pathogenicity of REPEC, we have used a newly constructed isogenic tir null mutant together with a previously described eae null mutant. When human HeLa epithelial cells were infected, the tir mutant was still able to induce the formation of stress fibers as previously reported for the eae null mutant. When the rabbit epithelial cell line RK13 was used, REPEC O103 produced a classical fluorescent actin staining (FAS) effect, whereas both the eae and tir mutants were FAS negative. In a rabbit ligated ileal loop model, neither mutant was able to induce A/E lesions. In contrast to the parental strain, which intimately adhered to the enterocytes and destroyed the brush border microvilli, bacteria of both mutants were clustered in the mucus without reaching and damaging the microvilli. The role of intimin and Tir was then analyzed in vivo by oral inoculation of weaned rabbits. Although both mutants were still present in the intestinal flora of the rabbits 3 weeks after oral inoculation, neither mutant strain induced any clinical signs or significant weight loss in the inoculated rabbits whereas the parental strain caused the death of 90% of the inoculated rabbits. Nevertheless, an inflammatory infiltrate was present in the lamina propria of the rabbits infected with both mutants, with an inflammatory response greater for the eae null mutant. In conclusion, we have confirmed the role of intimin in virulence, and we have shown, for the first time, that Tir is also a key factor in vivo for pathogenicity.
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Affiliation(s)
- O Marchès
- Unité Mixte de Microbiologie Moléculaire, Institut National de la Recherche Agronomique-Ecole Nationale Vétérinaire de Toulouse, 31076 Toulouse Cedex, France
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