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Sharafutdinov I, Knorr J, Rottner K, Backert S, Tegtmeyer N. Cortactin: A universal host cytoskeletal target of Gram-negative and Gram-positive bacterial pathogens. Mol Microbiol 2022; 118:623-636. [PMID: 36396951 DOI: 10.1111/mmi.15002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/04/2022] [Accepted: 11/07/2022] [Indexed: 11/19/2022]
Abstract
Pathogenic bacteria possess a great potential of causing infectious diseases and represent a serious threat to human and animal health. Understanding the molecular basis of infection development can provide new valuable strategies for disease prevention and better control. In host-pathogen interactions, actin-cytoskeletal dynamics play a crucial role in the successful adherence, invasion, and intracellular motility of many intruding microbial pathogens. Cortactin, a major cellular factor that promotes actin polymerization and other functions, appears as a central regulator of host-pathogen interactions and different human diseases including cancer development. Various important microbes have been reported to hijack cortactin signaling during infection. The primary regulation of cortactin appears to proceed via serine and/or tyrosine phosphorylation events by upstream kinases, acetylation, and interaction with various other host proteins, including the Arp2/3 complex, filamentous actin, the actin nucleation promoting factor N-WASP, focal adhesion kinase FAK, the large GTPase dynamin-2, the guanine nucleotide exchange factor Vav2, and the actin-stabilizing protein CD2AP. Given that many signaling factors can affect cortactin activities, several microbes target certain unique pathways, while also sharing some common features. Here we review our current knowledge of the hallmarks of cortactin as a major target for eminent Gram-negative and Gram-positive bacterial pathogens in humans.
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Affiliation(s)
- Irshad Sharafutdinov
- Department of Biology, Division of Microbiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jakob Knorr
- Department of Biology, Division of Microbiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Klemens Rottner
- Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Steffen Backert
- Department of Biology, Division of Microbiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Nicole Tegtmeyer
- Department of Biology, Division of Microbiology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Helicobacter pylori CagA Induces Cortactin Y-470 Phosphorylation-Dependent Gastric Epithelial Cell Scattering via Abl, Vav2 and Rac1 Activation. Cancers (Basel) 2021; 13:cancers13164241. [PMID: 34439396 PMCID: PMC8391897 DOI: 10.3390/cancers13164241] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/10/2021] [Accepted: 08/15/2021] [Indexed: 12/12/2022] Open
Abstract
Simple Summary Various microbial pathogens target the actin-binding protein cortactin to promote their own uptake, proliferation and spread, and exhibit proposed roles in human cancerogenesis. We aimed to study the molecular mechanisms of how the gastric pathogen Helicobacter pylori hijacks cortactin phosphorylation via tyrosine kinase Abl to trigger cancer-related signal transduction events. We discovered that cortactin phosphorylated at Y-470 recruits the signaling factor Vav2 to activate the small Rho GTPase Rac1, and finally, a cancer cell motility phenotype. We also demonstrate that phosphorylation of cortactin at Y-470 can be completely inhibited by the well-known Abl inhibitor imatinib. Imatinib is an established oral chemotherapy medication, employed for efficient systemic treatment of various cancers. These results reveal a comprehensive novel pathway for how precisely H. pylori manipulates host signaling in gastric disease development, and may pave the way for new opportunities of treatment of the outcome of infections with this pathogen, i.e., through using imatinib. Abstract The pathogen Helicobacter pylori is the first reported bacterial type-1 carcinogen playing a role in the development of human malignancies, including gastric adenocarcinoma. Cancer cell motility is an important process in this scenario, however, the molecular mechanisms are still not fully understood. Here, we demonstrate that H. pylori subverts the actin-binding protein cortactin through its type-IV secretion system and injected oncoprotein CagA, e.g., by inducing tyrosine phosphorylation of cortactin at Y-470, which triggers gastric epithelial cell scattering and motility. During infection of AGS cells, cortactin was discovered to undergo tyrosine dephosphorylation at residues Y-421 and Y-486, which is mediated through inactivation of Src kinase. However, H. pylori also profoundly activates tyrosine kinase Abl, which simultaneously phosphorylates cortactin at Y-470. Phosphorylated cortactin interacts with the SH2-domain of Vav2, a guanine nucleotide exchange factor for the Rho-family of GTPases. The cortactin/Vav2 complex then stimulates a previously unrecognized activation cascade including the small GTPase Rac1, to effect actin rearrangements and cell scattering. We hypothesize that injected CagA targets cortactin to locally open the gastric epithelium in order to get access to certain nutrients. This may disturb the cellular barrier functions, likely contributing to the induction of cell motility, which is important in gastric cancer development.
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Kassa EG, Zlotkin-Rivkin E, Friedman G, Ramachandran RP, Melamed-Book N, Weiss AM, Belenky M, Reichmann D, Breuer W, Pal RR, Rosenshine I, Lapierre LA, Goldenring JR, Aroeti B. Enteropathogenic Escherichia coli remodels host endosomes to promote endocytic turnover and breakdown of surface polarity. PLoS Pathog 2019; 15:e1007851. [PMID: 31242273 PMCID: PMC6615643 DOI: 10.1371/journal.ppat.1007851] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 07/09/2019] [Accepted: 05/20/2019] [Indexed: 12/11/2022] Open
Abstract
Enteropathogenic E. coli (EPEC) is an extracellular diarrheagenic human pathogen which infects the apical plasma membrane of the small intestinal enterocytes. EPEC utilizes a type III secretion system to translocate bacterial effector proteins into its epithelial hosts. This activity, which subverts numerous signaling and membrane trafficking pathways in the infected cells, is thought to contribute to pathogen virulence. The molecular and cellular mechanisms underlying these events are not well understood. We investigated the mode by which EPEC effectors hijack endosomes to modulate endocytosis, recycling and transcytosis in epithelial host cells. To this end, we developed a flow cytometry-based assay and imaging techniques to track endosomal dynamics and membrane cargo trafficking in the infected cells. We show that type-III secreted components prompt the recruitment of clathrin (clathrin and AP2), early (Rab5a and EEA1) and recycling (Rab4a, Rab11a, Rab11b, FIP2, Myo5b) endocytic machineries to peripheral plasma membrane infection sites. Protein cargoes, e.g. transferrin receptors, β1 integrins and aquaporins, which exploit the endocytic pathways mediated by these machineries, were also found to be recruited to these sites. Moreover, the endosomes and cargo recruitment to infection sites correlated with an increase in cargo endocytic turnover (i.e. endocytosis and recycling) and transcytosis to the infected plasma membrane. The hijacking of endosomes and associated endocytic activities depended on the translocated EspF and Map effectors in non-polarized epithelial cells, and mostly on EspF in polarized epithelial cells. These data suggest a model whereby EPEC effectors hijack endosomal recycling mechanisms to mislocalize and concentrate host plasma membrane proteins in endosomes and in the apically infected plasma membrane. We hypothesize that these activities contribute to bacterial colonization and virulence. Enteropathogenic Escherichia coli (EPEC) are pathogenic bacteria that cause infantile diarrhea. Upon ingestion, EPEC reaches the small intestine, where an injection device termed the type III secretion system is utilized to inject a set of effector proteins from the bacteria into the host cell. These proteins manipulate the localization and functions of host proteins, lipids and organelles and contribute to the emergence of the EPEC disease. The molecular mechanisms underlying the functions of the EPEC effector proteins are not completely understood. Here we show that early upon infection, two such effector proteins, EspF and Map, hijack host endosomes at bacterial adherence sites to facilitate endocytosis and recycling of plasma membrane proteins at these sites. The consequence of this event is the enrichment and mislocalization of host plasma membrane proteins at infection sites. One such protein is the transferrin receptor, which is a carrier for transferrin, whose function is to mediate cellular uptake of iron. Iron is a critical nutrient for bacterial growth and survival. We postulate that the unique manipulation of transferrin receptor endocytic membrane trafficking by EPEC plays an important role in its survival on the luminal surface of the intestinal epithelium.
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Affiliation(s)
- Ephrem G. Kassa
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Efrat Zlotkin-Rivkin
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Gil Friedman
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rachana P. Ramachandran
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Naomi Melamed-Book
- Bio-imaging Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Aryeh M. Weiss
- Bio-imaging Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- Faculty of Engineering, Bar Ilan University, Ramat Gan, Israel
| | - Michael Belenky
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Dana Reichmann
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- Proteomics and Mass Spectrometry Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - William Breuer
- Proteomics and Mass Spectrometry Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ritesh Ranjan Pal
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ilan Rosenshine
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lynne A. Lapierre
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - James R. Goldenring
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Benjamin Aroeti
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail:
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Abstract
Enterohemorrhagic Escherichia coli (EHEC) has two critical virulence factors—a type III secretion system (T3SS) and Shiga toxins (Stxs)—that are required for the pathogen to colonize the intestine and cause diarrheal disease. Here, we carried out a genome-wide CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats with Cas9) loss-of-function screen to identify host loci that facilitate EHEC infection of intestinal epithelial cells. Many of the guide RNAs identified targeted loci known to be associated with sphingolipid biosynthesis, particularly for production of globotriaosylceramide (Gb3), the Stx receptor. Two loci (TM9SF2 and LAPTM4A) with largely unknown functions were also targeted. Mutations in these loci not only rescued cells from Stx-mediated cell death, but also prevented cytotoxicity associated with the EHEC T3SS. These mutations interfered with early events associated with T3SS and Stx pathogenicity, markedly reducing entry of T3SS effectors into host cells and binding of Stx. The convergence of Stx and T3SS onto overlapping host targets provides guidance for design of new host-directed therapeutic agents to counter EHEC infection. Enterohemorrhagic Escherichia coli (EHEC) has two critical virulence factors—a type III secretion system (T3SS) and Shiga toxins (Stxs)—that are required for colonizing the intestine and causing diarrheal disease. We screened a genome-wide collection of CRISPR mutants derived from intestinal epithelial cells and identified mutants with enhanced survival following EHEC infection. Many had mutations that disrupted synthesis of a subset of lipids (sphingolipids) that includes the Stx receptor globotriaosylceramide (Gb3) and hence protect against Stx intoxication. Unexpectedly, we found that sphingolipids also mediate early events associated with T3SS pathogenicity. Since antibiotics are contraindicated for the treatment of EHEC, therapeutics targeting sphingolipid biosynthesis are a promising alternative, as they could provide protection against both of the pathogen’s key virulence factors.
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Stradal TEB, Costa SCP. Type III Secreted Virulence Factors Manipulating Signaling to Actin Dynamics. Curr Top Microbiol Immunol 2016; 399:175-199. [PMID: 27744505 DOI: 10.1007/82_2016_35] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A key aspect of bacterial pathogenesis is the colonization and persistence within the host and, later on, its dissemination to new niches. During evolution, bacteria developed a myriad of virulence mechanisms to usurp the host's sophisticated defense mechanisms in order to establish their colonization niche. Elucidation of the highly dynamic and complex interactions between host and pathogens remains an important field of study. Here, we highlight the conserved manipulation of the actin cytoskeleton by some Gram-negative gastrointestinal pathogens, addressing the role of type III secreted bacterial GEFs at the different steps of pathogenesis. As a final topic, we review cytoskeleton dynamics induced by EPEC/EHEC strains for pedestal formation.
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Affiliation(s)
- Theresia E B Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Baunschweig, Germany.
| | - Sonia C P Costa
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Baunschweig, Germany
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Blasche S, Arens S, Ceol A, Siszler G, Schmidt MA, Häuser R, Schwarz F, Wuchty S, Aloy P, Uetz P, Stradal T, Koegl M. The EHEC-host interactome reveals novel targets for the translocated intimin receptor. Sci Rep 2014; 4:7531. [PMID: 25519916 PMCID: PMC4269881 DOI: 10.1038/srep07531] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 11/21/2014] [Indexed: 12/20/2022] Open
Abstract
Enterohemorrhagic E. coli (EHEC) manipulate their human host through at least 39 effector proteins which hijack host processes through direct protein-protein interactions (PPIs). To identify their protein targets in the host cells, we performed yeast two-hybrid screens, allowing us to find 48 high-confidence protein-protein interactions between 15 EHEC effectors and 47 human host proteins. In comparison to other bacteria and viruses we found that EHEC effectors bind more frequently to hub proteins as well as to proteins that participate in a higher number of protein complexes. The data set includes six new interactions that involve the translocated intimin receptor (TIR), namely HPCAL1, HPCAL4, NCALD, ARRB1, PDE6D, and STK16. We compared these TIR interactions in EHEC and enteropathogenic E. coli (EPEC) and found that five interactions were conserved. Notably, the conserved interactions included those of serine/threonine kinase 16 (STK16), hippocalcin-like 1 (HPCAL1) as well as neurocalcin-delta (NCALD). These proteins co-localize with the infection sites of EPEC. Furthermore, our results suggest putative functions of poorly characterized effectors (EspJ, EspY1). In particular, we observed that EspJ is connected to the microtubule system while EspY1 appears to be involved in apoptosis/cell cycle regulation.
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Affiliation(s)
- Sonja Blasche
- Genomics and Proteomics Core Facilities, German Cancer Research Center, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Stefan Arens
- Institute of Molecular Cell Biology, University of Münster, Schlossplatz 5, D-48149 Münster
| | - Arnaud Ceol
- 1] Joint IRB-BSC Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain [2] Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Via Adamello 16, 20139 Milan - Italy
| | - Gabriella Siszler
- Genomics and Proteomics Core Facilities, German Cancer Research Center, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - M Alexander Schmidt
- Institute of Infectiology, ZMBE, University of Münster, Von-Esmarch-Str. 56, D-48149 Münster
| | - Roman Häuser
- Genomics and Proteomics Core Facilities, German Cancer Research Center, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Frank Schwarz
- Genomics and Proteomics Core Facilities, German Cancer Research Center, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Stefan Wuchty
- 1] Dept. of Computer Science, Univ. of Miami, 1365 Memorial Drive, Coral Gables, FL 33146, USA [2] Center for Computational Science, Univ. of Miami, 1365 Memorial Drive, Coral Gables, FL 33146, USA
| | - Patrick Aloy
- 1] Joint IRB-BSC Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain [2] Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA 23284, USA
| | - Theresia Stradal
- 1] Institute of Molecular Cell Biology, University of Münster, Schlossplatz 5, D-48149 Münster [2] Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124 Braunschweig
| | - Manfred Koegl
- Genomics and Proteomics Core Facilities, German Cancer Research Center, Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
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In J, Lukyanenko V, Foulke-Abel J, Hubbard AL, Delannoy M, Hansen AM, Kaper JB, Boisen N, Nataro JP, Zhu C, Boedeker EC, Girón JA, Kovbasnjuk O. Serine protease EspP from enterohemorrhagic Escherichia coli is sufficient to induce shiga toxin macropinocytosis in intestinal epithelium. PLoS One 2013; 8:e69196. [PMID: 23874912 PMCID: PMC3715455 DOI: 10.1371/journal.pone.0069196] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 06/05/2013] [Indexed: 12/14/2022] Open
Abstract
Life-threatening intestinal and systemic effects of the Shiga toxins produced by enterohemorrhagic Escherichia coli (EHEC) require toxin uptake and transcytosis across intestinal epithelial cells. We have recently demonstrated that EHEC infection of intestinal epithelial cells stimulates toxin macropinocytosis, an actin-dependent endocytic pathway. Host actin rearrangement necessary for EHEC attachment to enterocytes is mediated by the type 3 secretion system which functions as a molecular syringe to translocate bacterial effector proteins directly into host cells. Actin-dependent EHEC attachment also requires the outer membrane protein intimin, a major EHEC adhesin. Here, we investigate the role of type 3 secretion in actin turnover occurring during toxin macropinocytosis. Toxin macropinocytosis is independent of EHEC type 3 secretion and intimin attachment. EHEC soluble factors are sufficient to stimulate macropinocytosis and deliver toxin into enterocytes in vitro and in vivo; intact bacteria are not required. Intimin-negative enteroaggregative Escherichia coli (EAEC) O104:H4 robustly stimulate Shiga toxin macropinocytosis into intestinal epithelial cells. The apical macropinosomes formed in intestinal epithelial cells move through the cells and release their cargo at these cells' basolateral sides. Further analysis of EHEC secreted proteins shows that a serine protease EspP alone is able to stimulate host actin remodeling and toxin macropinocytosis. The observation that soluble factors, possibly serine proteases including EspP, from each of two genetically distinct toxin-producing strains, can stimulate Shiga toxin macropinocytosis and transcellular transcytosis alters current ideas concerning mechanisms whereby Shiga toxin interacts with human enterocytes. Mechanisms important for this macropinocytic pathway could suggest new potential therapeutic targets for Shiga toxin-induced disease.
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Affiliation(s)
- Julie In
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Valeriy Lukyanenko
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jennifer Foulke-Abel
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Ann L. Hubbard
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Michael Delannoy
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Anne-Marie Hansen
- Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James B. Kaper
- Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Nadia Boisen
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - James P. Nataro
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Chengru Zhu
- Department of Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Edgar C. Boedeker
- Department of Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, United States of America
| | - Jorge A. Girón
- Department of Molecular Genetics and Microbiology, Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
| | - Olga Kovbasnjuk
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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Rosales EM, Aguilera MO, Salinas RP, Carminati SA, Colombo MI, Martinez-Quiles N, Berón W. Cortactin is involved in the entry of Coxiella burnetii into non-phagocytic cells. PLoS One 2012; 7:e39348. [PMID: 22761768 PMCID: PMC3382237 DOI: 10.1371/journal.pone.0039348] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 05/24/2012] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Cortactin is a key regulator of the actin cytoskeleton and is involved in pathogen-host cell interactions. Numerous pathogens exploit the phagocytic process and actin cytoskeleton to infect host cells. Coxiella burnetii, the etiologic agent of Q fever, is internalized by host cells through a molecular mechanism that is poorly understood. METHODOLOGY/PRINCIPAL FINDING Here we analyzed the role of different cortactin motifs in the internalization of C. burnetii by non-phagocytic cells. C. burnetii internalization into HeLa cells was significantly reduced when the cells expressed GFP-cortactin W525K, which carries a mutation in the SH3 domain that renders the protein unable to bind targets such as N-WASP. However, internalization was unaffected when the cells expressed the W22A mutant, which has a mutation in the N-terminal acidic region that destroys the protein's ability to bind and activate Arp2/3. We also determined whether the phosphorylation status of cortactin is important for internalization. Expression of GFP-cortactin 3F, which lacks phosphorylatable tyrosines, significantly increased internalization of C. burnetii, while expression of GFP-cortactin 3D, a phosphotyrosine mimic, did not affect it. In contrast, expression of GFP-cortactin 2A, which lacks phosphorylatable serines, inhibited C. burnetii internalization, while expression of GFP-cortactin SD, a phosphoserine mimic, did not affect it. Interestingly, inhibitors of Src kinase and the MEK-ERK kinase pathway blocked internalization. In fact, both kinases reached maximal activity at 15 min of C. burnetii infection, after which activity decreased to basal levels. Despite the decrease in kinase activity, cortactin phosphorylation at Tyr421 reached a peak at 1 h of infection. CONCLUSIONS/SIGNIFICANCE Our results suggest that the SH3 domain of cortactin is implicated in C. burnetii entry into HeLa cells. Furthermore, cortactin phosphorylation at serine and dephosphorylation at tyrosine favor C. burnetii internalization. We present evidence that ERK and Src kinases play a role early in infection by this pathogen.
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Affiliation(s)
- Eliana M. Rosales
- Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina
| | - Milton O. Aguilera
- Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina
| | - Romina P. Salinas
- Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina
| | - Sergio A. Carminati
- Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina
| | - María I. Colombo
- Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina
| | | | - Walter Berón
- Instituto de Histología y Embriología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina
- * E-mail:
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Campellone KG, Siripala AD, Leong JM, Welch MD. Membrane-deforming proteins play distinct roles in actin pedestal biogenesis by enterohemorrhagic Escherichia coli. J Biol Chem 2012; 287:20613-24. [PMID: 22544751 DOI: 10.1074/jbc.m112.363473] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Many bacterial pathogens reorganize the host actin cytoskeleton during the course of infection, including enterohemorrhagic Escherichia coli (EHEC), which utilizes the effector protein EspF(U) to assemble actin filaments within plasma membrane protrusions called pedestals. EspF(U) activates N-WASP, a host actin nucleation-promoting factor that is normally auto-inhibited and found in a complex with the actin-binding protein WIP. Under native conditions, this N-WASP/WIP complex is activated by the small GTPase Cdc42 in concert with several different SH3 (Src-homology-3) domain-containing proteins. In the current study, we tested whether SH3 domains from the F-BAR (FCH-Bin-Amphiphysin-Rvs) subfamily of membrane-deforming proteins are involved in actin pedestal formation. We found that three F-BAR proteins: CIP4, FBP17, and TOCA1 (transducer of Cdc42-dependent actin assembly), play different roles during actin pedestal biogenesis. Whereas CIP4 and FBP17 inhibited actin pedestal assembly, TOCA1 stimulated this process. TOCA1 was recruited to pedestals by its SH3 domain, which bound directly to proline-rich sequences within EspF(U). Moreover, EspF(U) and TOCA1 activated the N-WASP/WIP complex in an additive fashion in vitro, suggesting that TOCA1 can augment actin assembly within pedestals. These results reveal that EspF(U) acts as a scaffold to recruit multiple actin assembly factors whose functions are normally regulated by Cdc42.
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Affiliation(s)
- Kenneth G Campellone
- Department of Molecular & Cell Biology, University of Connecticut, Storrs, Connecticut 06269, USA.
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Tegtmeyer N, Wittelsberger R, Hartig R, Wessler S, Martinez-Quiles N, Backert S. Serine phosphorylation of cortactin controls focal adhesion kinase activity and cell scattering induced by Helicobacter pylori. Cell Host Microbe 2011; 9:520-31. [PMID: 21669400 DOI: 10.1016/j.chom.2011.05.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 04/29/2011] [Accepted: 05/25/2011] [Indexed: 02/04/2023]
Abstract
Cell migration and invasion require the coordinated regulation of cytoskeletal architectural changes by signaling factors, including the actin-binding protein cortactin. Bacterial and viral pathogens subvert these signaling factors to promote their uptake, spread and dissemination. We show that the gastric pathogen Helicobacter pylori (Hp) targets cortactin by two independent processes leading to its tyrosine dephosphorylation and serine phosphorylation to regulate cell scattering and elongation. The phosphorylation status of cortactin dictates its subcellular localization and signaling partners. Upon infection, cortactin was found to interact with and stimulate the kinase activity of focal adhesion kinase (FAK). This interaction required the SH3 domain and phosphorylation of cortactin at serine 405 and a proline-rich sequence in FAK. Using Hp as a model, this study unravels a previously unrecognized FAK activation pathway. We propose that Hp targets cortactin to protect the gastric epithelium from excessive cell lifting and ensure sustained infection in the stomach.
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Affiliation(s)
- Nicole Tegtmeyer
- Department of Microbiology, Otto von Guericke University, Leipziger Strasse 44, D-39120 Magdeburg, Germany
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Wong ARC, Pearson JS, Bright MD, Munera D, Robinson KS, Lee SF, Frankel G, Hartland EL. Enteropathogenic and enterohaemorrhagic Escherichia coli: even more subversive elements. Mol Microbiol 2011; 80:1420-38. [PMID: 21488979 DOI: 10.1111/j.1365-2958.2011.07661.x] [Citation(s) in RCA: 256] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alexander R C Wong
- Centre for Molecular Microbiology and Infection, Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK
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Padash-Barmchi M, Browne K, Sturgeon K, Jusiak B, Auld VJ. Control of Gliotactin localization and levels by tyrosine phosphorylation and endocytosis is necessary for survival of polarized epithelia. J Cell Sci 2010; 123:4052-62. [PMID: 21045109 DOI: 10.1242/jcs.066605] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The tricellular junction (TCJ) forms at the convergence of bicellular junctions from three adjacent cells in polarized epithelia and is necessary for maintaining the transepithelial barrier. In the fruitfly Drosophila, the TCJ is generated at the meeting point of bicellular septate junctions. Gliotactin was the first identified component of the TCJ and is necessary for TCJ and septate junction development. Gliotactin is a member of the neuroligin family and associates with the PDZ protein discs large. Beyond this interaction, little is known about the mechanisms underlying Gliotactin localization and function at the TCJ. In this study, we show that Gliotactin is phosphorylated at conserved tyrosine residues, a process necessary for endocytosis and targeting to late endosomes and lysosomes for degradation. Regulation of Gliotactin levels through phosphorylation and endocytosis is necessary as overexpression results in displacement of Gliotactin away from the TCJ throughout the septate junction domain. Excessive Gliotactin in polarized epithelia leads to delamination, paired with subsequent migration, and apoptosis. The apoptosis and the resulting compensatory proliferation resulting from high levels of Gliotactin are mediated by the Drosophila JNK pathway. Therefore, Gliotactin levels within the cell membrane are regulated to ensure correct protein localization and cell survival.
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Affiliation(s)
- Mojgan Padash-Barmchi
- Department of Zoology, Cell and Developmental Biology, University of British Columbia, Vancouver, Canada BC V6T 1Z3
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13
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Campellone KG. Cytoskeleton-modulating effectors of enteropathogenic and enterohaemorrhagic Escherichia coli: Tir, EspFU and actin pedestal assembly. FEBS J 2010; 277:2390-402. [PMID: 20477869 DOI: 10.1111/j.1742-4658.2010.07653.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A variety of microbes manipulate the cytoskeleton of mammalian cells to promote their internalization, motility and/or spread. Among such bacteria, enteropathogenic Escherichia coli and enterohemorrhagic Escherichia coli are closely related pathogens that adhere to human intestinal cells and reorganize the underlying actin cytoskeleton into 'pedestals'. The assembly of pedestals is likely to be an important step in colonization, and is triggered by the E. coli virulence factors translocated intimin receptor and E. coli secreted protein F in prophage U, which modulate multiple host signaling cascades that lead to actin polymerization. In recent years, these bacterial effectors have been exploited as powerful experimental tools for investigating actin cytoskeletal and membrane dynamics, and several studies have significantly advanced our understanding of the regulation of actin assembly in mammalian cells and the potential role of pedestal formation in pathogenesis.
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Affiliation(s)
- Kenneth G Campellone
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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14
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Nieto-Pelegrin E, Martinez-Quiles N. Distinct phosphorylation requirements regulate cortactin activation by TirEPEC and its binding to N-WASP. Cell Commun Signal 2009; 7:11. [PMID: 19419567 PMCID: PMC2686683 DOI: 10.1186/1478-811x-7-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 05/06/2009] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Cortactin activates the actin-related 2/3 (Arp2/3) complex promoting actin polymerization to remodel cell architecture in multiple processes (e.g. cell migration, membrane trafficking, invadopodia formation etc.). Moreover, it was called the Achilles' heel of the actin cytoskeleton because many pathogens hijack signals that converge on this oncogenic scaffolding protein. Cortactin is able to modulate N-WASP activation in vitro in a phosphorylation-dependent fashion. Thus Erk-phosphorylated cortactin is efficient in activating N-WASP through its SH3 domain, while Src-phosphorylated cortactin is not. This could represent a switch on/off mechanism controlling the coordinated action of both nucleator promoting factors (NPFs). Pedestal formation by enteropathogenic Escherichia coli (EPEC) requires N-WASP activation. N-WASP is recruited by the cell adapter Nck which binds a major tyrosine-phosphorylated site of a bacterial injected effector, Tir (translocated intimin receptor). Tir-Nck-N-WASP axis defines the current major pathway to actin polymerization on pedestals. In addition, it was recently reported that EPEC induces tyrosine phosphorylation of cortactin. RESULTS Here we demonstrate that cortactin phosphorylation is absent on N-WASP deficient cells, but is recovered by re-expression of N-WASP. We used purified recombinant cortactin and Tir proteins to demonstrate a direct interaction of both that promoted Arp2/3 complex-mediated actin polymerization in vitro, independently of cortactin phosphorylation. CONCLUSION We propose that cortactin binds Tir through its N-terminal part in a tyrosine and serine phosphorylation independent manner while SH3 domain binding and activation of N-WASP is regulated by tyrosine and serine mediated phosphorylation of cortactin. Therefore cortactin could act on Tir-Nck-N-WASP pathway and control a possible cycling activity of N-WASP underlying pedestal formation.
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Affiliation(s)
- Elvira Nieto-Pelegrin
- Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.
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15
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Huett A, Leong JM, Podolsky DK, Xavier RJ. The cytoskeletal scaffold Shank3 is recruited to pathogen-induced actin rearrangements. Exp Cell Res 2009; 315:2001-11. [PMID: 19371741 DOI: 10.1016/j.yexcr.2009.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Revised: 03/14/2009] [Accepted: 04/06/2009] [Indexed: 01/25/2023]
Abstract
The common gastrointestinal pathogens enteropathogenic Escherichia coli (EPEC) and Salmonella typhimurium both reorganize the gut epithelial cell actin cytoskeleton to mediate pathogenesis, utilizing mimicry of the host signaling apparatus. The PDZ domain-containing protein Shank3, is a large cytoskeletal scaffold protein with known functions in neuronal morphology and synaptic signaling, and is also capable of acting as a scaffolding adaptor during Ret tyrosine kinase signaling in epithelial cells. Using immunofluorescent and functional RNA-interference approaches we show that Shank3 is present in both EPEC- and S. typhimurium-induced actin rearrangements and is required for optimal EPEC pedestal formation. We propose that Shank3 is one of a number of host synaptic proteins likely to play key roles in bacteria-host interactions.
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Affiliation(s)
- Alan Huett
- Gastrointestinal Unit, Center for the Study of Inflammatory Bowel Diseases, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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16
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Hirakawa H, Kodama T, Takumi-Kobayashi A, Honda T, Yamaguchi A. Secreted indole serves as a signal for expression of type III secretion system translocators in enterohaemorrhagic Escherichia coli O157:H7. MICROBIOLOGY-SGM 2009; 155:541-550. [PMID: 19202102 DOI: 10.1099/mic.0.020420-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Indole is produced by tryptophanase during growth of enteric bacteria and accumulates in the culture medium. The physiological role of indole production is poorly understood. We discovered that enterohaemorrhagic Escherichia coli (EHEC) O157:H7 with a tnaA deletion has decreased secretion of EspA and EspB via the type III secretion system and as a result there is reduced formation of attaching and effacing (A/E) lesions in HeLa cells. Addition of indole restored and enhanced secretion of EspA and EspB and formation of A/E lesions by the tnaA deletion mutant EHEC. Indole addition moderately increased the promoter activity of LEE4 genes, including espA and espB, in the locus of enterocyte effacement. Thus in EHEC indole can serve to signal EspA and EspB expression and secretion and stimulate the ability of EHEC to form A/E lesions on human cells.
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Affiliation(s)
- Hidetada Hirakawa
- Department of Microbiology, University of Washington, WA 98195, USA.,Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Toshio Kodama
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Asuka Takumi-Kobayashi
- Graduate School of Pharmaceutical Science, Osaka University, Suita, Osaka 565-0871, Japan.,Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Takeshi Honda
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
| | - Akihito Yamaguchi
- Graduate School of Pharmaceutical Science, Osaka University, Suita, Osaka 565-0871, Japan.,Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
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Sal-Man N, Biemans-Oldehinkel E, Finlay BB. Structural microengineers: pathogenic Escherichia coli redesigns the actin cytoskeleton in host cells. Structure 2009; 17:15-9. [PMID: 19141278 DOI: 10.1016/j.str.2008.12.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 12/01/2008] [Accepted: 12/08/2008] [Indexed: 11/18/2022]
Abstract
Several virulent bacteria have the ability to manipulate the host cell actin cytoskeleton as part of their pathogenic strategy. These pathogens subvert the host cell actin polymerization machinery for various purposes including motility within host cells, cell-to-cell spread, and to prevent phagocytic engulfment by professional phagocytes. In contrast to intracellular pathogens, pathogenic Escherichia coli (including both enterohemorrhagic and enteropathogenic E. coli) subvert actin polymerization from an extracellular position to facilitate adherence. This review summarizes recent data on the mechanisms by which pathogenic E. coli hijack members of the Wiskott-Aldrich syndrome protein family to manipulate actin polymerization within host cells, including the novel, and surprisingly simple, mechanism recently revealed for the EspFu effector.
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Affiliation(s)
- Neta Sal-Man
- Michael Smith Laboratories, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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IRSp53 Links the Enterohemorrhagic E. coli Effectors Tir and EspFU for Actin Pedestal Formation. Cell Host Microbe 2009; 5:244-58. [DOI: 10.1016/j.chom.2009.02.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2008] [Revised: 12/30/2008] [Accepted: 02/11/2009] [Indexed: 12/20/2022]
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Hamaguchi M, Hamada D, Suzuki KN, Sakata I, Yanagihara I. Molecular basis of actin reorganization promoted by binding of enterohaemorrhagic Escherichia coli EspB to α-catenin. FEBS J 2008; 275:6260-7. [DOI: 10.1111/j.1742-4658.2008.06750.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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20
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Campellone KG, Cheng HC, Robbins D, Siripala AD, McGhie EJ, Hayward RD, Welch MD, Rosen MK, Koronakis V, Leong JM. Repetitive N-WASP-binding elements of the enterohemorrhagic Escherichia coli effector EspF(U) synergistically activate actin assembly. PLoS Pathog 2008; 4:e1000191. [PMID: 18974829 PMCID: PMC2567903 DOI: 10.1371/journal.ppat.1000191] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Accepted: 09/30/2008] [Indexed: 11/19/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) generate F-actin–rich adhesion pedestals by delivering effector proteins into mammalian cells. These effectors include the translocated receptor Tir, along with EspFU, a protein that associates indirectly with Tir and contains multiple peptide repeats that stimulate actin polymerization. In vitro, the EspFU repeat region is capable of binding and activating recombinant derivatives of N-WASP, a host actin nucleation-promoting factor. In spite of the identification of these important bacterial and host factors, the underlying mechanisms of how EHEC so potently exploits the native actin assembly machinery have not been clearly defined. Here we show that Tir and EspFU are sufficient for actin pedestal formation in cultured cells. Experimental clustering of Tir-EspFU fusion proteins indicates that the central role of the cytoplasmic portion of Tir is to promote clustering of the repeat region of EspFU. Whereas clustering of a single EspFU repeat is sufficient to bind N-WASP and generate pedestals on cultured cells, multi-repeat EspFU derivatives promote actin assembly more efficiently. Moreover, the EspFU repeats activate a protein complex containing N-WASP and the actin-binding protein WIP in a synergistic fashion in vitro, further suggesting that the repeats cooperate to stimulate actin polymerization in vivo. One explanation for repeat synergy is that simultaneous engagement of multiple N-WASP molecules can enhance its ability to interact with the actin nucleating Arp2/3 complex. These findings define the minimal set of bacterial effectors required for pedestal formation and the elements within those effectors that contribute to actin assembly via N-WASP-Arp2/3–mediated signaling pathways. Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a food-borne pathogen that causes diarrhea and life-threatening systemic illnesses. EHEC colonizes the intestine by adhering tightly to host cells and injecting bacterial molecules that trigger the formation of a “pedestal” below bound bacteria. These pedestals are generated by reorganizing the actin cytoskeleton into densely packed filaments beneath the plasma membrane. Pedestal formation is therefore not only important for EHEC disease, it provides a means to study how mammalian cells control their shape. We show here that two EHEC proteins, Tir and EspFU, are sufficient to trigger pedestal formation. Tir localizes to the mammalian plasma membrane, and its central function is to promote clustering of EspFU. EspFU contains multiple repeat sequences that stimulate actin polymerization by binding N-WASP, a host protein that initiates actin assembly. Although a single repeat of EspFU can generate pedestals, multi-repeat variants promote actin assembly cooperatively. One explanation for this synergy is that tandem repeats can potently trigger the formation of a complex of mammalian proteins that modulate the actin cytoskeleton. These findings define the minimal set of EHEC effectors required for pedestal formation and the elements within those effectors that confer their ability to alter cell shape.
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Affiliation(s)
- Kenneth G. Campellone
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California United States of America
| | - Hui-Chun Cheng
- Department of Biochemistry and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Douglas Robbins
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Anosha D. Siripala
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California United States of America
| | - Emma J. McGhie
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Richard D. Hayward
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Matthew D. Welch
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California United States of America
| | - Michael K. Rosen
- Department of Biochemistry and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Vassilis Koronakis
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - John M. Leong
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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Cortactin recruitment by enterohemorrhagic Escherichia coli O157:H7 during infection in vitro and ex vivo. Infect Immun 2008; 76:4669-76. [PMID: 18678675 DOI: 10.1128/iai.00140-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is an important human pathogen that colonizes the gut mucosa via attaching and effacing (A/E) lesions; A/E lesion formation in vivo and ex vivo is dependent on the type III secretion system (T3SS) effector Tir. Infection of cultured cells by EHEC leads to induction of localized actin polymerization, which is dependent on Tir and a second T3SS effector protein, TccP, also known as EspF(U). Recently, cortactin was shown to bind both the N terminus of Tir and TccP via its SH3 domain and to play a role in EHEC-triggered actin polymerization in vitro. In this study, we investigated the recruitment of cortactin to the site of EHEC adhesion during infection of in vitro-cultured cells and mucosal surfaces ex vivo (using human terminal ileal in vitro organ cultures [IVOC]). We have shown that cortactin is recruited to the site of EHEC adhesion in vitro downstream of TccP and N-WASP. Deletion of the entire N terminus of Tir or replacing the N-terminal polyproline region with alanines did not abrogate actin polymerization or cortactin recruitment. In contrast, recruitment of cortactin to the site of EHEC adhesion in IVOC is TccP independent. These results imply that cortactin is recruited to the site of EHEC adhesion in vitro and ex vivo by different mechanisms and suggest that cortactin might have a role during EHEC infection of mucosal surfaces.
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Frankel G, Phillips AD. Attaching effacing Escherichia coli and paradigms of Tir-triggered actin polymerization: getting off the pedestal. Cell Microbiol 2007; 10:549-56. [PMID: 18053003 DOI: 10.1111/j.1462-5822.2007.01103.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC) colonize the gut mucosa via attaching and effacing (A/E) lesions. For years cultured cells were used as model systems to study A/E lesion formation, which showed actin accumulation under attached bacteria that can be raised above the plasma membrane in a pedestal-shaped structure. Studies of prototypical strains revealed that although both converge on N-WASP EPEC and EHEC O157:H7 use different actin polymerization pathways. While EPEC use the Tir-Nck pathway, Tir(EHECO157) cooperates with TccP/EspF(U) to activate N-WASP. However, recent in vitro studies revealed a common EPEC and EHEC Tir-dependent and Nck-independent inefficient actin polymerization pathway. Unexpectedly, bacterial populations studies demonstrated that most non-O157 EHEC strains and EPEC lineage 2 strains can utilize both the Nck and TccP2 pathways in vitro. Importantly, in vivo and ex vivo mucosal infections have shown efficient A/E lesion formation independently of Nck and TccP. This review covers the progression in our understanding of EPEC and EHEC infection, through the different milestones obtained using cultured cells, to the realization that EPEC and EHEC have much more in common than previously appreciated and that mucosal attachment and microvillous effacement may be the key events, rather than pedestal formation.
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Affiliation(s)
- Gad Frankel
- Division of Cell and Molecular Biology, Imperial College London, London, UK.
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