1
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Noh SS, Shin HJ. Role of Virus-Induced EGFR Trafficking in Proviral Functions. Biomolecules 2023; 13:1766. [PMID: 38136637 PMCID: PMC10741569 DOI: 10.3390/biom13121766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 11/30/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
Since its discovery in the early 1980s, the epidermal growth factor receptor (EGFR) has emerged as a pivotal and multifaceted player in elucidating the intricate mechanisms underlying various human diseases and their associations with cell survival, proliferation, and cellular homeostasis. Recent advancements in research have underscored the profound and multifaceted role of EGFR in viral infections, highlighting its involvement in viral entry, replication, and the subversion of host immune responses. In this regard, the importance of EGFR trafficking has also been highlighted in recent studies. The dynamic relocation of EGFR to diverse intracellular organelles, including endosomes, lysosomes, mitochondria, and even the nucleus, is a central feature of its functionality in diverse contexts. This dynamic intracellular trafficking is not merely a passive process but an orchestrated symphony, facilitating EGFR involvement in various cellular pathways and interactions with viral components. Furthermore, EGFR, which is initially anchored on the plasma membrane, serves as a linchpin orchestrating viral entry processes, a crucial early step in the viral life cycle. The role of EGFR in this context is highly context-dependent and varies among viruses. Here, we present a comprehensive summary of the current state of knowledge regarding the intricate interactions between EGFR and viruses. These interactions are fundamental for successful propagation of a wide array of viral species and affect viral pathogenesis and host responses. Understanding EGFR significance in both normal cellular processes and viral infections may not only help develop innovative antiviral therapies but also provide a deeper understanding of the intricate roles of EGFR signaling in infectious diseases.
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Affiliation(s)
- Se Sil Noh
- Department of Microbiology, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea;
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
- Brain Korea 21 FOUR Project for Medical Science, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Hye Jin Shin
- Department of Microbiology, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea;
- Department of Medical Science, Chungnam National University School of Medicine, Daejeon 35015, Republic of Korea
- Research Institute for Medical Sciences, College of Medicine, Chungnam National University, Daejeon 34134, Republic of Korea
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2
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Valenzuela-Valderas KN, Farrashzadeh E, Chang YY, Shi Y, Raudonis R, Leung BM, Rohde JR, Enninga J, Cheng Z. RACK1 promotes Shigella flexneri actin-mediated invasion, motility, and cell-to-cell spreading. iScience 2023; 26:108216. [PMID: 37953961 PMCID: PMC10637933 DOI: 10.1016/j.isci.2023.108216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 08/19/2023] [Accepted: 10/11/2023] [Indexed: 11/14/2023] Open
Abstract
Shigella flexneri is an intracellular bacterium that hijacks the host actin cytoskeleton to invade and disseminate within the colonic epithelium. Shigella's virulence factors induce actin polymerization, leading to bacterial uptake, actin tail formation, actin-mediated motility, and cell-to-cell spreading. Many host factors involved in the Shigella-prompted actin rearrangements remain elusive. Here, we studied the role of a host protein receptor for activated C kinase 1 (RACK1) in actin cytoskeleton dynamics and Shigella infection. We used time-lapse imaging to demonstrate that RACK1 facilitates Shigella-induced actin cytoskeleton remodeling at multiple levels during infection of epithelial cells. Silencing RACK1 expression impaired Shigella-induced rapid polymerizing structures, reducing host cell invasion, bacterial motility, and cell-to-cell spreading. In uninfected cells, RACK1 silencing reduced jasplakinolide-mediated filamentous actin aggregate formation and negatively affected actin turnover in fast polymerizing structures, such as membrane ruffles. Our findings provide a role of RACK1 in actin cytoskeleton dynamics and Shigella infection.
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Affiliation(s)
| | - Elmira Farrashzadeh
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Yuen-Yan Chang
- Unité Dynamique des interactions hôtes-pathogènes, Institut Pasteur and CNRS UMR3691, Université de Paris-Cité, 75724 Paris, France
| | - Yunnuo Shi
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Renee Raudonis
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Brendan M. Leung
- Department of Applied Oral Sciences, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - John R. Rohde
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Jost Enninga
- Unité Dynamique des interactions hôtes-pathogènes, Institut Pasteur and CNRS UMR3691, Université de Paris-Cité, 75724 Paris, France
| | - Zhenyu Cheng
- Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada
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3
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Nasser A, Mosadegh M, Azimi T, Shariati A. Molecular mechanisms of Shigella effector proteins: a common pathogen among diarrheic pediatric population. Mol Cell Pediatr 2022; 9:12. [PMID: 35718793 PMCID: PMC9207015 DOI: 10.1186/s40348-022-00145-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 05/06/2022] [Indexed: 12/16/2022] Open
Abstract
Different gastrointestinal pathogens cause diarrhea which is a very common problem in children aged under 5 years. Among bacterial pathogens, Shigella is one of the main causes of diarrhea among children, and it accounts for approximately 11% of all deaths among children aged under 5 years. The case-fatality rates for Shigella among the infants and children aged 1 to 4 years are 13.9% and 9.4%, respectively. Shigella uses unique effector proteins to modulate intracellular pathways. Shigella cannot invade epithelial cells on the apical site; therefore, it needs to pass epithelium through other cells rather than the epithelial cell. After passing epithelium, macrophage swallows Shigella, and the latter should prepare itself to exhibit at least two types of responses: (I) escaping phagocyte and (II) mediating invasion of and injury to the recurrent PMN. The presence of PMN and invitation to a greater degree resulted in gut membrane injuries and greater bacterial penetration. Infiltration of Shigella to the basolateral space mediates (A) cell attachment, (B) cell entry, (C) evasion of autophagy recognition, (D) vacuole formation and and vacuole rapture, (E) intracellular life, (F) Shiga toxin, and (G) immune response. In this review, an attempt is made to explain the role of each factor in Shigella infection.
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Affiliation(s)
- Ahmad Nasser
- Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehrdad Mosadegh
- Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Taher Azimi
- Department of Bacteriology & Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
| | - Aref Shariati
- Molecular and medicine research center, Khomein University of Medical Sciences, Khomein, Iran
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4
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Donhauser N, Socher E, Millen S, Heym S, Sticht H, Thoma-Kress AK. Transfer of HTLV-1 p8 and Gag to target T-cells depends on VASP, a novel interaction partner of p8. PLoS Pathog 2020; 16:e1008879. [PMID: 32997728 PMCID: PMC7526893 DOI: 10.1371/journal.ppat.1008879] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 08/12/2020] [Indexed: 12/16/2022] Open
Abstract
The Human T-cell leukemia virus type 1 (HTLV-1) orf I-encoded accessory protein p8 is cleaved from its precursor p12, and both proteins contribute to viral persistence. p8 induces cellular protrusions, which are thought to facilitate transfer of p8 to target cells and virus transmission. Host factors interacting with p8 and mediating p8 transfer are unknown. Here, we report that vasodilator-stimulated phosphoprotein (VASP), which promotes actin filament elongation, is a novel interaction partner of p8 and important for p8 and HTLV-1 Gag cell-to-cell transfer. VASP contains an Ena/VASP homology 1 (EVH1) domain that targets the protein to focal adhesions. Bioinformatics identified a short stretch in p8 (amino acids (aa) 24–45) which may mediate interactions with the EVH1 domain of VASP. Co-immunoprecipitations confirmed interactions of VASP:p8 in 293T, Jurkat and HTLV-1-infected MT-2 cells. Co-precipitation of VASP:p8 could be significantly blocked by peptides mimicking aa 26–37 of p8. Mutational studies revealed that the EVH1-domain of VASP is necessary, but not sufficient for the interaction with p8. Further, deletion of the VASP G- and F-actin binding domains significantly diminished co-precipitation of p8. Imaging identified areas of partial co-localization of VASP with p8 at the plasma membrane and in protrusive structures, which was confirmed by proximity ligation assays. Co-culture experiments revealed that p8 is transferred between Jurkat T-cells via VASP-containing conduits. Imaging and flow cytometry revealed that repression of both endogenous and overexpressed VASP by RNA interference or by CRISPR/Cas9 reduced p8 transfer to the cell surface and to target Jurkat T-cells. Stable repression of VASP by RNA interference in chronically infected MT-2 cells impaired both p8 and HTLV-1 Gag transfer to target Jurkat T-cells, while virus release was unaffected. Thus, we identified VASP as a novel interaction partner of p8, which is important for transfer of HTLV-1 p8 and Gag to target T-cells. The delta-retrovirus Human T-cell leukemia virus type 1 encodes the accessory protein p8, which is generated by proteolytic cleavage from p12. Earlier work has shown that p8 enhances the formation of cellular conduits between T-cells, is transferred through these conduits to target T-cells and increases HTLV-1 transmission. It was suggested that p8 dampens T-cell responses in target T-cells, thus facilitating HTLV-1 infection. Our work sheds light on the mechanism of p8 transfer to target T-cells. We show that vasodilator-stimulated phosphoprotein (VASP), a novel interaction partner of p8, contributes to transfer of p8 to target T-cells. Mechanistically, VASP is crucial for recruitment of p8 to the cell surface. Since VASP is known to promote elongation of actin filaments by preventing them from capping, interactions of p8 with VASP are an elegant strategy to exploit the host cell machinery for being transported to the cell surface, and as a consequence, to other cells. Given that VASP is also important for cell-to-cell transfer of the HTLV-1 Gag protein, our work proposes that VASP is a new cellular target to counteract HTLV-1 cell-to-cell transmission.
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Affiliation(s)
- Norbert Donhauser
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Eileen Socher
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Sebastian Millen
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Stefanie Heym
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Andrea K. Thoma-Kress
- Institute of Clinical and Molecular Virology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- * E-mail:
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5
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Abstract
The bacterial pathogen Shigella flexneri causes more than 250 million cases of bacillary dysentery (blood in stool) every year across the world. This human-specific disease is characterized by profuse bloody diarrhea, dramatic ulceration of the colonic epithelium and immune cell infiltration of the colonic tissue. A major challenge in understanding the mechanisms supporting bacillary dysentery is the reliance on animal models that do not fully recapitulate the symptoms observed in humans, including bloody diarrhea. Here we outline advances provided by a recently developed infant rabbit model of bacillary dysentery. The infant rabbit model defines bacillary dysentery as a critical combination of massive vascular lesions and dramatic epithelial fenestration due to intracellular infection and cell-to-cell spread, respectively. The infant rabbit model provides an unprecedented framework for understanding how the cell biology of Shigella flexneri infection relates to pathogenesis.
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Affiliation(s)
- Lauren K. Yum
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA, USA,CONTACT Hervé Agaisse Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia22908, USA
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6
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The virulence domain of Shigella IcsA contains a subregion with specific host cell adhesion function. PLoS One 2020; 15:e0227425. [PMID: 31910229 PMCID: PMC6946128 DOI: 10.1371/journal.pone.0227425] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/18/2019] [Indexed: 02/08/2023] Open
Abstract
Shigella species cause bacillary dysentery, especially among young individuals. Shigellae target the human colon for invasion; however, the initial adhesion mechanism is poorly understood. The Shigella surface protein IcsA, in addition to its role in actin-based motility, acts as a host cell adhesin through unknown mechanism(s). Here we confirmed the role of IcsA in cell adhesion and defined the region required for IcsA adhesin activity. Purified IcsA passenger domain was able block S. flexneri adherence and was also used as a molecular probe that recognised multiple components from host cells. The region within IcsA's functional passenger domain (aa 138-148) was identified by mutagenesis. Upon the deletion of this region, the purified IcsAΔ138-148 was found to no longer block S. flexneri adherence and had reduced ability to interact with host molecules. Furthermore, S. flexneri expressing IcsAΔ138-148 was found to be significantly defective in both cell adherence and invasion. Taken together, our data identify an adherence region within the IcsA functional domain and provides useful information for designing therapeutics for Shigella infection.
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7
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Functional screenings reveal different requirements for host microRNAs in Salmonella and Shigella infection. Nat Microbiol 2019; 5:192-205. [DOI: 10.1038/s41564-019-0614-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 10/18/2019] [Indexed: 12/15/2022]
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8
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Michard C, Yum LK, Agaisse H. WIPF2 promotesShigella flexneriactin‐based motility and cell‐to‐cell spread. Cell Microbiol 2019; 21:e13098. [DOI: 10.1111/cmi.13098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 08/08/2019] [Accepted: 08/10/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Céline Michard
- Department of Microbiology, Immunology, and Cancer BiologyUniversity of Virginia Charlottesville Virginia
| | - Lauren K. Yum
- Department of Microbiology, Immunology, and Cancer BiologyUniversity of Virginia Charlottesville Virginia
| | - Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer BiologyUniversity of Virginia Charlottesville Virginia
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9
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Abstract
The entry of pathogens into nonphagocytic host cells has received much attention in the past three decades, revealing a vast array of strategies employed by bacteria and viruses. A method of internalization that has been extensively studied in the context of viral infections is the use of the clathrin-mediated pathway. More recently, a role for clathrin in the entry of some intracellular bacterial pathogens was discovered. Classically, clathrin-mediated endocytosis was thought to accommodate internalization only of particles smaller than 150 nm; however, this was challenged upon the discovery that Listeria monocytogenes requires clathrin to enter eukaryotic cells. Now, with discoveries that clathrin is required during other stages of some bacterial infections, another paradigm shift is occurring. There is a more diverse impact of clathrin during infection than previously thought. Much of the recent data describing clathrin utilization in processes such as bacterial attachment, cell-to-cell spread and intracellular growth may be due to newly discovered divergent roles of clathrin in the cell. Not only does clathrin act to facilitate endocytosis from the plasma membrane, but it also participates in budding from endosomes and the Golgi apparatus and in mitosis. Here, the manipulation of clathrin processes by bacterial pathogens, including its traditional role during invasion and alternative ways in which clathrin supports bacterial infection, is discussed. Researching clathrin in the context of bacterial infections will reveal new insights that inform our understanding of host-pathogen interactions and allow researchers to fully appreciate the diverse roles of clathrin in the eukaryotic cell.
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Affiliation(s)
- Eleanor A Latomanski
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Hayley J Newton
- Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
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10
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De Souza Santos M, Orth K. The Role of the Type III Secretion System in the Intracellular Lifestyle of Enteric Pathogens. Microbiol Spectr 2019; 7:10.1128/microbiolspec.bai-0008-2019. [PMID: 31152523 PMCID: PMC11026088 DOI: 10.1128/microbiolspec.bai-0008-2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Indexed: 11/20/2022] Open
Abstract
Several pathogens have evolved to infect host cells from within, which requires subversion of many host intracellular processes. In the case of Gram-negative pathogenic bacteria, adaptation to an intracellular life cycle relies largely on the activity of type III secretion systems (T3SSs), an apparatus used to deliver effector proteins into the host cell, from where these effectors regulate important cellular functions such as vesicular trafficking, cytoskeleton reorganization, and the innate immune response. Each bacterium is equipped with a unique suite of these T3SS effectors, which aid in the development of an individual intracellular lifestyle for their respective pathogens. Some bacteria adapt to reside and propagate within a customized vacuole, while others establish a replicative niche in the host cytosol. In this article, we review the mechanisms by which T3SS effectors contribute to these different lifestyles. To illustrate the formation of a vacuolar and a cytosolic lifestyle, we discuss the intracellular habitats of the enteric pathogens Salmonella enterica serovar Typhimurium and Shigella flexneri, respectively. These represent well-characterized systems that function as informative models to contribute to our understanding of T3SS-dependent subversion of intracellular processes. Additionally, we present Vibrio parahaemolyticus, another enteric Gram-negative pathogen, as an emerging model for future studies of the cytosolic lifestyle.
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Affiliation(s)
- Marcela De Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Biochemistry and
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
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11
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Yum LK, Byndloss MX, Feldman SH, Agaisse H. Critical role of bacterial dissemination in an infant rabbit model of bacillary dysentery. Nat Commun 2019; 10:1826. [PMID: 31015451 PMCID: PMC6478941 DOI: 10.1038/s41467-019-09808-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 03/28/2019] [Indexed: 11/09/2022] Open
Abstract
The bacterial pathogen Shigella flexneri causes 270 million cases of bacillary dysentery (blood in stool) worldwide every year, resulting in more than 200,000 deaths. A major challenge in combating bacillary dysentery is the lack of a small-animal model that recapitulates the symptoms observed in infected individuals, including bloody diarrhea. Here, we show that similar to humans, infant rabbits infected with S. flexneri experience severe inflammation, massive ulceration of the colonic mucosa, and bloody diarrhea. T3SS-dependent invasion of epithelial cells is necessary and sufficient for mediating immune cell infiltration and vascular lesions. However, massive ulceration of the colonic mucosa, bloody diarrhea, and dramatic weight loss are strictly contingent on the ability of the bacteria to spread from cell to cell. The infant rabbit model features bacterial dissemination as a critical determinant of S. flexneri pathogenesis and provides a unique small-animal model for research and development of therapeutic interventions.
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Affiliation(s)
- Lauren K Yum
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
| | - Mariana X Byndloss
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sanford H Feldman
- Center for Comparative Medicine, University of Virginia, Charlottesville, VA, USA
| | - Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA.
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12
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Abstract
Cardiolipin, an anionic phospholipid that resides at the poles of the inner and outer membranes, is synthesized primarily by the putative cardiolipin synthase ClsA in Shigella flexneri. An S. flexneri clsA mutant had no cardiolipin detected within its membrane, grew normally in vitro, and invaded cultured epithelial cells, but it failed to form plaques in epithelial cell monolayers, indicating that cardiolipin is required for virulence. The clsA mutant was initially motile within the host cell cytoplasm but formed filaments and lost motility during replication and failed to spread efficiently to neighboring cells. Mutation of pbgA, which encodes the transporter for cardiolipin from the inner membrane to the outer membrane, also resulted in loss of plaque formation. The S. flexneri pbgA mutant had normal levels of cardiolipin in the inner membrane, but no cardiolipin was detected in the outer membrane. The pbgA mutant invaded and replicated normally within cultured epithelial cells but failed to localize the actin polymerization protein IcsA properly on the bacterial surface and was unable to spread to neighboring cells. The clsA mutant, but not the pbgA mutant, had increased phosphatidylglycerol in the outer membrane. This appeared to compensate partially for the loss of cardiolipin in the outer membrane, allowing some IcsA localization in the outer membrane of the clsA mutant. We propose a dual function for cardiolipin in S. flexneri pathogenesis. In the inner membrane, cardiolipin is essential for proper cell division during intracellular growth. In the outer membrane, cardiolipin facilitates proper presentation of IcsA on the bacterial surface. The human pathogen Shigella flexneri causes bacterial dysentery by invading colonic epithelial cells, rapidly multiplying within their cytoplasm, and then spreading intercellularly to neighboring cells. Worldwide, Shigella spp. infect hundreds of millions of people annually, with fatality rates up to 15%. Antibiotic treatment of Shigella infections is compromised by increasing antibiotic resistance, and there is no approved vaccine to prevent future infections. This has created a growing need to understand Shigella pathogenesis and identify new targets for antimicrobial therapeutics. Here we show a previously unknown role of phospholipids in S. flexneri pathogenesis. We demonstrate that cardiolipin is required in the outer membrane for proper surface localization of IcsA and in the inner membrane for cell division during growth in the host cell cytoplasm.
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13
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Mauricio RPM, Jeffries CM, Svergun DI, Deane JE. The Shigella Virulence Factor IcsA Relieves N-WASP Autoinhibition by Displacing the Verprolin Homology/Cofilin/Acidic (VCA) Domain. J Biol Chem 2017; 292:134-145. [PMID: 27881679 PMCID: PMC5217673 DOI: 10.1074/jbc.m116.758003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 11/09/2016] [Indexed: 11/10/2022] Open
Abstract
Shigella flexneri is a bacterial pathogen that invades cells of the gastrointestinal tract, causing severe dysentery. Shigella mediates intracellular motility and spreading via actin comet tail formation. This process is dependent on the surface-exposed, membrane-embedded virulence factor IcsA, which recruits the host actin regulator N-WASP. Although it is clear that Shigella requires N-WASP for this process, the molecular details of this interaction and the mechanism of N-WASP activation remain poorly understood. Here, we show that co-expression of full-length IcsA and the Shigella membrane protease IcsP yields highly pure IcsA passenger domain (residues 53-758). We show that IcsA is monomeric and describe the solution structure of the passenger domain obtained by small-angle X-ray scattering (SAXS) analysis. The SAXS-derived models suggest that IcsA has an elongated shape but, unlike most other autotransporter proteins, possesses a central kink revealing a distinctly curved structure. Pull-down experiments show direct binding of the IcsA passenger domain to both the WASP homology 1 (WH1) domain and the GTPase binding domain (GBD) of N-WASP and no binding to the verprolin homology/cofilin/acidic (VCA) region. Using fluorescence polarization experiments, we demonstrate that IcsA binding to the GBD region displaces the VCA peptide and that this effect is synergistically enhanced upon IcsA binding to the WH1 region. Additionally, domain mapping of the IcsA interaction interface reveals that different regions of IcsA bind to the WH1 and GBD domains of N-WASP. Taken together, our data support a model where IcsA and N-WASP form a tight complex releasing the N-WASP VCA domain to recruit the host cell machinery for actin tail formation.
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Affiliation(s)
- Rui P M Mauricio
- From the Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom and
| | - Cy M Jeffries
- the European Molecular Biology Laboratory (EMBL), Hamburg Outstation, c/o DESY, Hamburg 22067, Germany
| | - Dmitri I Svergun
- the European Molecular Biology Laboratory (EMBL), Hamburg Outstation, c/o DESY, Hamburg 22067, Germany
| | - Janet E Deane
- From the Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom and
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14
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Agaisse H. Molecular and Cellular Mechanisms of Shigella flexneri Dissemination. Front Cell Infect Microbiol 2016; 6:29. [PMID: 27014639 PMCID: PMC4786538 DOI: 10.3389/fcimb.2016.00029] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/26/2016] [Indexed: 11/13/2022] Open
Abstract
The intracellular pathogen Shigella flexneri is the causative agent of bacillary dysentery in humans. The disease is characterized by bacterial invasion of intestinal cells, dissemination within the colonic epithelium through direct spread from cell to cell, and massive inflammation of the intestinal mucosa. Here, we review the mechanisms supporting S. flexneri dissemination. The dissemination process primarily relies on actin assembly at the bacterial pole, which propels the pathogen throughout the cytosol of primary infected cells. Polar actin assembly is supported by polar expression of the bacterial autotransporter family member IcsA, which recruits the N-WASP/ARP2/3 actin assembly machinery. As motile bacteria encounter cell-cell contacts, they form plasma membrane protrusions that project into adjacent cells. In addition to the ARP2/3-dependent actin assembly machinery, protrusion formation relies on formins and myosins. The resolution of protrusions into vacuoles occurs through the collapse of the protrusion neck, leading to the formation of an intermediate membrane-bound compartment termed vacuole-like protrusions (VLPs). VLP formation requires tyrosine kinase and phosphoinositide signaling in protrusions, which relies on the integrity of the bacterial type 3 secretion system (T3SS). The T3SS is also required for escaping double membrane vacuoles through the activity of the T3SS translocases IpaB and IpaC, and the effector proteins VirA and IcsB. Numerous factors supporting envelope biogenesis contribute to IcsA exposure and maintenance at the bacterial pole, including LPS synthesis, membrane proteases, and periplasmic chaperones. Although less characterized, the assembly and function of the T3SS in the context of bacterial dissemination also relies on factors supporting envelope biogenesis. Finally, the dissemination process requires the adaptation of the pathogen to various cellular compartments through transcriptional and post-transcriptional mechanisms.
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Affiliation(s)
- Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine Charlottesville, VA, USA
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15
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Kühn S, Mannherz HG. Actin: Structure, Function, Dynamics, and Interactions with Bacterial Toxins. Curr Top Microbiol Immunol 2016; 399:1-34. [PMID: 27848038 DOI: 10.1007/82_2016_45] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
Actin is one of the most abundant proteins in any eukaryotic cell and an indispensable component of the cytoskeleton. In mammalian organisms, six highly conserved actin isoforms can be distinguished, which differ by only a few amino acids. In non-muscle cells, actin polymerizes into actin filaments that form actin structures essential for cell shape stabilization, and participates in a number of motile activities like intracellular vesicle transport, cytokinesis, and also cell locomotion. Here, we describe the structure of monomeric and polymeric actin, the polymerization kinetics, and its regulation by actin-binding proteins. Probably due to its conserved nature and abundance, actin and its regulating factors have emerged as prefered targets of bacterial toxins and effectors, which subvert the host actin cytoskeleton to serve bacterial needs.
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Affiliation(s)
- Sonja Kühn
- Department of Cell Biology and Infection, Institut Pasteur, Paris, France
| | - Hans Georg Mannherz
- Department of Anatomy and Molecular Embryology, Ruhr-University, Bochum, Germany.
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16
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Van Nhieu GT, Romero S. Common Themes in Cytoskeletal Remodeling by Intracellular Bacterial Effectors. Handb Exp Pharmacol 2016; 235:207-235. [PMID: 27807696 DOI: 10.1007/164_2016_42] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Bacterial pathogens interact with various types of tissues to promote infection. Because it controls the formation of membrane extensions, adhesive processes, or the junction integrity, the actin cytoskeleton is a key target of pathogens during infection. We will highlight common and specific functions of the actin cytoskeleton during bacterial infections, by first reviewing the mechanisms of intracellular motility of invasive Shigella, Listeria, and Rickettsia. Through the models of EPEC/EHEC, Shigella, Salmonella, and Chlamydia spp., we will illustrate various strategies of diversion of actin cytoskeletal processes used by these bacteria to colonize or breach epithelial/endothelial barriers.
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Affiliation(s)
- Guy Tran Van Nhieu
- Equipe Communication Intercellulaire et Infections Microbiennes, Centre de Recherche Interdisciplinaire en Biologie (CIRB), Collège de France, 75005, Paris, France. .,Institut National de la Santé et de la Recherche Médicale U1050, 75005, Paris, France. .,Centre National de la Recherche Scientifique UMR7241, 75005, Paris, France. .,MEMOLIFE Laboratory of Excellence and Paris Science Lettre, 75005, Paris, France.
| | - Stéphane Romero
- Equipe Communication Intercellulaire et Infections Microbiennes, Centre de Recherche Interdisciplinaire en Biologie (CIRB), Collège de France, 75005, Paris, France.,Institut National de la Santé et de la Recherche Médicale U1050, 75005, Paris, France.,Centre National de la Recherche Scientifique UMR7241, 75005, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre, 75005, Paris, France
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17
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Doyle MT, Grabowicz M, Morona R. A small conserved motif supports polarity augmentation of Shigella flexneri IcsA. MICROBIOLOGY-SGM 2015; 161:2087-97. [PMID: 26315462 DOI: 10.1099/mic.0.000165] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The rod-shaped enteric intracellular pathogen Shigella flexneri and other Shigella species are the causative agents of bacillary dysentery. S. flexneri are able to spread within the epithelial lining of the gut, resulting in lesion formation, cramps and bloody stools. The outer membrane protein IcsA is essential for this spreading process. IcsA is the initiator of an actin-based form of motility whereby it allows the formation of a filamentous actin 'tail' at the bacterial pole. Importantly, IcsA is specifically positioned at the bacterial pole such that this process occurs asymmetrically. The mechanism of IcsA polarity is not completely understood, but it appears to be a multifactorial process involving factors intrinsic to IcsA and other regulating factors. In this study, we further investigated IcsA polarization by its intramolecular N-terminal and central polar-targeting (PT) regions (nPT and cPT regions, respectively). The results obtained support a role in polar localization for the cPT region and contend the role of the nPT region. We identified single IcsA residues that have measurable impacts on IcsA polarity augmentation, resulting in decreased S. flexneri sprading efficiency. Intriguingly, regions and residues involved in PT clustered around a highly conserved motif which may provide a functional scaffold for polarity-augmenting residues. How these results fit with the current model of IcsA polarity determination is discussed.
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Affiliation(s)
- Matthew Thomas Doyle
- 1Department of Molecular and Cellular Biology, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Marcin Grabowicz
- 2Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, USA
| | - Renato Morona
- 1Department of Molecular and Cellular Biology, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
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18
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Kuehl CJ, Dragoi AM, Talman A, Agaisse H. Bacterial spread from cell to cell: beyond actin-based motility. Trends Microbiol 2015; 23:558-66. [PMID: 26021574 DOI: 10.1016/j.tim.2015.04.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/14/2015] [Accepted: 04/28/2015] [Indexed: 01/01/2023]
Abstract
Several intracellular pathogens display the ability to propagate within host tissues by displaying actin-based motility in the cytosol of infected cells. As motile bacteria reach cell-cell contacts they form plasma membrane protrusions that project into adjacent cells and resolve into vacuoles from which the pathogen escapes, thereby achieving spread from cell to cell. Seminal studies have defined the bacterial and cellular factors that support actin-based motility. By contrast, the mechanisms supporting the formation of protrusions and their resolution into vacuoles have remained elusive. Here, we review recent advances in the field showing that Listeria monocytogenes and Shigella flexneri have evolved pathogen-specific mechanisms of bacterial spread from cell to cell.
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Affiliation(s)
- Carole J Kuehl
- Department of Microbial Pathogenesis, Yale School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT, USA
| | - Ana-Maria Dragoi
- Department of Microbial Pathogenesis, Yale School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT, USA
| | - Arthur Talman
- Department of Microbial Pathogenesis, Yale School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT, USA
| | - Hervé Agaisse
- Department of Microbial Pathogenesis, Yale School of Medicine, Boyer Center for Molecular Medicine, New Haven, CT, USA.
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19
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Doyle MT, Tran ENH, Morona R. The passenger-associated transport repeat promotes virulence factor secretion efficiency and delineates a distinct autotransporter subtype. Mol Microbiol 2015; 97:315-29. [PMID: 25869731 DOI: 10.1111/mmi.13027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2015] [Indexed: 11/28/2022]
Abstract
Autotransporters are a superfamily of virulence factors secreted by Gram negative bacteria. They are comprised of an N-terminal passenger domain that is translocated across the outer membrane and a C-terminal domain that inserts into the outer membrane forming a β-barrel anchor. It is still poorly understood how the passenger is efficiently translocated in the absence of external energy inputs. Several mechanisms have been proposed in solution of this problem, yet due to the vast diversity of size, sequence and function of the passenger, it is not clear how widely these mechanisms are employed. In this study we functionally characterize a conserved repeat found in many passengers that we designate the Passenger-associated Transport Repeat (PATR). Using the autotransporter IcsA from the enteropathogen Shigella flexneri, we identified conserved PATR residues that are required for efficient export of the passenger during growth and infection. Furthermore, PATR-containing autotransporters are significantly larger than non-PATR autotransporters, with PATR copy number correlating with passenger size. We also show that PATR-containing autotransporters delineate a subgroup that associates with specific virulence traits and architectures. These results advance our understanding of autotransporter composition and indicate that an additional transport mechanism is important for thousands of these proteins.
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Affiliation(s)
- Matthew Thomas Doyle
- Department of Molecular and Cellular Biology, School of Biological Sciences, Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Elizabeth Ngoc Hoa Tran
- Department of Molecular and Cellular Biology, School of Biological Sciences, Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Renato Morona
- Department of Molecular and Cellular Biology, School of Biological Sciences, Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
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20
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Doyle MT, Grabowicz M, May KL, Morona R. Lipopolysaccharide surface structure does not influence IcsA polarity. FEMS Microbiol Lett 2015; 362:fnv042. [DOI: 10.1093/femsle/fnv042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2015] [Indexed: 12/26/2022] Open
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21
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The class II phosphatidylinositol 3-phosphate kinase PIK3C2A promotes Shigella flexneri dissemination through formation of vacuole-like protrusions. Infect Immun 2015; 83:1695-704. [PMID: 25667265 DOI: 10.1128/iai.03138-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Intracellular pathogens such as Shigella flexneri and Listeria monocytogenes achieve dissemination in the intestinal epithelium by displaying actin-based motility in the cytosol of infected cells. As they reach the cell periphery, motile bacteria form plasma membrane protrusions that resolve into vacuoles in adjacent cells, through a poorly understood mechanism. Here, we report on the role of the class II phosphatidylinositol 3-phosphate kinase PIK3C2A in S. flexneri dissemination. Time-lapse microscopy revealed that PIK3C2A was required for the resolution of protrusions into vacuoles through the formation of an intermediate membrane-bound compartment that we refer to as a vacuole-like protrusion (VLP). Genetic rescue of PIK3C2A depletion with RNA interference (RNAi)-resistant cDNA constructs demonstrated that VLP formation required the activity of PIK3C2A in primary infected cells. PIK3C2A expression was required for production of phosphatidylinositol 3-phosphate [PtdIns(3)P] at the plasma membrane surrounding protrusions. PtdIns(3)P production was not observed in the protrusions formed by L. monocytogenes, whose dissemination did not rely on PIK3C2A. PIK3C2A-mediated PtdIns(3)P production in S. flexneri protrusions was regulated by host cell tyrosine kinase signaling and relied on the integrity of the S. flexneri type 3 secretion system (T3SS). We suggest a model of S. flexneri dissemination in which the formation of VLPs is mediated by the PIK3C2A-dependent production of the signaling lipid PtdIns(3)P in the protrusion membrane, which relies on the T3SS-dependent activation of tyrosine kinase signaling in protrusions.
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The serine/threonine kinase STK11 promotes Shigella flexneri dissemination through establishment of cell-cell contacts competent for tyrosine kinase signaling. Infect Immun 2014; 82:4447-57. [PMID: 25114112 DOI: 10.1128/iai.02078-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shigella flexneri is an intracellular pathogen that disseminates in the intestinal epithelium by displaying actin-based motility. We found that although S. flexneri displayed comparable actin-based motilities in the cytosols of HeLa229 and HT-29 epithelial cell lines, the overall dissemination process was much more efficient in HT-29 cells. Time-lapse microscopy demonstrated that as motile bacteria reached the cell cortex in HT-29 cells, they formed membrane protrusions that resolved into vacuoles, from which the bacteria escaped and gained access to the cytosol of adjacent cells. In HeLa229 cells, S. flexneri also formed membrane protrusions that extended into adjacent cells, but the protrusions rarely resolved into vacuoles. Instead, the formed protrusions collapsed and retracted, bringing the bacteria back to the cytosol of the primary infected cells. Silencing the serine/threonine kinase STK11 (also known as LKB1) in HT-29 cells decreased the efficiency of protrusion resolution into vacuoles. Conversely, expressing STK11 in HeLa229 cells, which lack the STK11 locus, dramatically increased the efficiency of protrusion resolution into vacuoles. S. flexneri dissemination in HT-29 cells led to the local phosphorylation of tyrosine residues in protrusions, a signaling event that was not observed in HeLa229 cells but was restored in STK11-expressing HeLa229 cells. Treatment of HT-29 cells with the tyrosine kinase inhibitor imatinib abrogated tyrosine kinase signaling in protrusions, which correlated with a severe decrease in the efficiency of protrusion resolution into vacuoles. We suggest that the formation of STK11-dependent lateral cell-cell contacts competent for tyrosine kinase signaling promotes S. flexneri dissemination in epithelial cells.
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23
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Wu X, Cao MP, Shen YY, Chu KP, Tao WB, Song WT, Liu LP, Wang XH, Zheng YF, Chen SD, Zeng QL, Xia RH. Weak power frequency magnetic field acting similarly to EGF stimulation, induces acute activations of the EGFR sensitive actin cytoskeleton motility in human amniotic cells. PLoS One 2014; 9:e87626. [PMID: 24505297 PMCID: PMC3914819 DOI: 10.1371/journal.pone.0087626] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 12/16/2013] [Indexed: 12/30/2022] Open
Abstract
In this article, we have examined the motility-related effects of weak power frequency magnetic fields (MFs) on the epidermal growth factor receptor (EGFR)-sensitive motility mechanism, including the F-actin cytoskeleton, growth of invasive protrusions and the levels of signal molecules in human amniotic epithelial (FL) cells. Without extracellular EGF stimulation, the field stimulated a large growth of new protrusions, especially filopodia and lamellipodia, an increased population of vinculin-associated focal adhesions. And, an obvious reduction of stress fiber content in cell centers was found, corresponding to larger cell surface areas and decreased efficiency of actin assembly of FL cells in vitro, which was associated with a decrease in overall F-actin content and special distributions. These effects were also associated with changes in protein content or distribution patterns of the EGFR downstream motility-related signaling molecules. All of these effects are similar to those following epidermal growth factor (EGF) stimulation of the cells and are time dependent. These results suggest that power frequency MF exposure acutely affects the migration/motility-related actin cytoskeleton reorganization that is regulated by the EGFR-cytoskeleton signaling pathway. Therefore, upon the MF exposure, cells are likely altered to be ready to transfer into a state of migration in response to the stimuli.
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Affiliation(s)
- Xia Wu
- Physics Department, East China Normal University, Shanghai, China
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
| | - Mei-Ping Cao
- Physics Department, East China Normal University, Shanghai, China
| | - Yun-Yun Shen
- Bioelectromagnetics Laboratory, Zhejiang University, Hangzhou, China
| | - Ke-Ping Chu
- Physics Department, East China Normal University, Shanghai, China
| | - Wu-Bin Tao
- Physics Department, East China Normal University, Shanghai, China
| | - Wei-Tao Song
- Physics Department, East China Normal University, Shanghai, China
| | - Li-Ping Liu
- School of Life Sciences, Fudan University, Shanghai, China
| | - Xiang-Hui Wang
- Physics Department, East China Normal University, Shanghai, China
| | - Yu-Fang Zheng
- School of Life Sciences, Fudan University, Shanghai, China
| | - Shu-De Chen
- Physics Department, East China Normal University, Shanghai, China
| | - Qun-Li Zeng
- Bioelectromagnetics Laboratory, Zhejiang University, Hangzhou, China
| | - Ruo-Hong Xia
- Physics Department, East China Normal University, Shanghai, China
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China
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24
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Lum M, Attridge SR, Morona R. Impact of dynasore an inhibitor of dynamin II on Shigella flexneri infection. PLoS One 2013; 8:e84975. [PMID: 24367704 PMCID: PMC3868620 DOI: 10.1371/journal.pone.0084975] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 11/27/2013] [Indexed: 11/19/2022] Open
Abstract
Shigella flexneri remains a significant human pathogen due to high morbidity among children < 5 years in developing countries. One of the key features of Shigella infection is the ability of the bacterium to initiate actin tail polymerisation to disseminate into neighbouring cells. Dynamin II is associated with the old pole of the bacteria that is associated with F-actin tail formation. Dynamin II inhibition with dynasore as well as siRNA knockdown significantly reduced Shigella cell to cell spreading in vitro. The ocular mouse Sereny model was used to determine if dynasore could delay the progression of Shigella infection in vivo. While dynasore did not reduce ocular inflammation, it did provide significant protection against weight loss. Therefore dynasore's effects in vivo are unlikely to be related to the inhibition of cell spreading observed in vitro. We found that dynasore decreased S. flexneri-induced HeLa cell death in vitro which may explain the protective effect observed in vivo. These results suggest the administration of dynasore or a similar compound during Shigella infection could be a potential intervention strategy to alleviate disease symptoms.
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Affiliation(s)
- Mabel Lum
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia
| | - Stephen R. Attridge
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia
| | - Renato Morona
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia
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25
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Besingi RN, Chaney JL, Clark PL. An alternative outer membrane secretion mechanism for an autotransporter protein lacking a C-terminal stable core. Mol Microbiol 2013; 90:1028-45. [PMID: 24118465 DOI: 10.1111/mmi.12414] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/24/2013] [Indexed: 01/24/2023]
Abstract
Autotransporter (AT) proteins are a broad class of virulence factors from Gram-negative pathogens. AT outer membrane (OM) secretion appears simple in many regards, yet the mechanism that enables transport of the central AT 'passenger' across the OM remains unclear. OM secretion efficiency for two AT passengers is enhanced by approximately 20 kDa stable core at the C-terminus of the passenger, but studies on a broader range of AT proteins are needed in order to determine whether a stability difference between the passenger N- and C-terminus represents a truly common mechanistic feature. Yersinia pestis YapV is homologous to Shigella flexneri IcsA, and like IcsA, YapV recruits mammalian neural Wiskott-Aldrich syndrome protein (N-WASP). In vitro, the purified YapV passenger is functional and rich in β-sheet structure, but lacks a approximately 20 kDa C-terminal stable core. However, the N-terminal 49 residues of the YapV passenger globally destabilize the entire YapV passenger, enhancing its OM secretion efficiency. These results indicate that the contributions of AT passenger sequences to OM secretion efficiency extend beyond a C-terminal stable core, and highlight a role of the passenger N-terminus in reducing passenger stability in order to facilitate OM secretion of some AT proteins.
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Affiliation(s)
- Richard N Besingi
- Department of Chemistry & Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA
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26
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Alvarez DE, Agaisse H. The formin FHOD1 and the small GTPase Rac1 promote vaccinia virus actin-based motility. ACTA ACUST UNITED AC 2013; 202:1075-90. [PMID: 24062339 PMCID: PMC3787377 DOI: 10.1083/jcb.201303055] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Vaccinia virus actin–based motility relies on integration of the N-WASP–ARP2/3 and Rac1–FHOD1 pathways. Vaccinia virus dissemination relies on the N-WASP–ARP2/3 pathway, which mediates actin tail formation underneath cell-associated extracellular viruses (CEVs). Here, we uncover a previously unappreciated role for the formin FHOD1 and the small GTPase Rac1 in vaccinia actin tail formation. FHOD1 depletion decreased the number of CEVs forming actin tails and impaired the elongation rate of the formed actin tails. Recruitment of FHOD1 to actin tails relied on its GTPase binding domain in addition to its FH2 domain. In agreement with previous studies showing that FHOD1 is activated by the small GTPase Rac1, Rac1 was enriched and activated at the membrane surrounding actin tails. Rac1 depletion or expression of dominant-negative Rac1 phenocopied the effects of FHOD1 depletion and impaired the recruitment of FHOD1 to actin tails. FHOD1 overexpression rescued the actin tail formation defects observed in cells overexpressing dominant-negative Rac1. Altogether, our results indicate that, to display robust actin-based motility, vaccinia virus integrates the activity of the N-WASP–ARP2/3 and Rac1–FHOD1 pathways.
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Affiliation(s)
- Diego E Alvarez
- Department of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale School of Medicine, New Haven, CT, 06519
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27
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Abstract
Intracellular pathogens have developed elaborate mechanisms to exploit the different cellular systems of their unwilling hosts to facilitate their entry, replication, and survival. In particular, a diverse range of bacteria and viruses have evolved unique strategies to harness the power of Arp2/3-mediated actin polymerization to enhance their cell-to-cell spread. In this review, we discuss how studying these pathogens has revolutionized our molecular understanding of Arp2/3-dependent actin assembly and revealed key signaling pathways regulating actin assembly in cells. Future analyses of microbe-host interactions are likely to continue uncovering new mechanisms regulating actin assembly and dynamics, as well as unexpected cellular functions for actin. Further, studies with known and newly emerging pathogens will also undoubtedly continue to enhance our understanding of the role of the actin cytoskeleton during pathogenesis and potentially highlight future therapeutic approaches.
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Affiliation(s)
- Matthew D Welch
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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28
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Small-molecule inhibitor of the Shigella flexneri master virulence regulator VirF. Infect Immun 2013; 81:4220-31. [PMID: 24002059 DOI: 10.1128/iai.00919-13] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
VirF is an AraC family transcriptional activator that is required for the expression of virulence genes associated with invasion and cell-to-cell spread by Shigella flexneri, including multiple components of the type three secretion system (T3SS) machinery and effectors. We tested a small-molecule compound, SE-1 (formerly designated OSSL_051168), which we had identified as an effective inhibitor of the AraC family proteins RhaS and RhaR, for its ability to inhibit VirF. Cell-based reporter gene assays with Escherichia coli and Shigella, as well as in vitro DNA binding assays with purified VirF, demonstrated that SE-1 inhibited DNA binding and transcription activation (likely by blocking DNA binding) by VirF. Analysis of mRNA levels using real-time quantitative reverse transcription-PCR (qRT-PCR) further demonstrated that SE-1 reduced the expression of the VirF-dependent virulence genes icsA, virB, icsB, and ipaB in Shigella. We also performed eukaryotic cell invasion assays and found that SE-1 reduced invasion by Shigella. The effect of SE-1 on invasion required preincubation of Shigella with SE-1, in agreement with the hypothesis that SE-1 inhibited the expression of VirF-activated genes required for the formation of the T3SS apparatus and invasion. We found that the same concentrations of SE-1 had no detectable effects on the growth or metabolism of the bacterial cells or the eukaryotic host cells, respectively, indicating that the inhibition of invasion was not due to general toxicity. Overall, SE-1 appears to inhibit transcription activation by VirF, exhibits selectivity toward AraC family proteins, and has the potential to be developed into a novel antibacterial agent.
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29
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Teh MY, Morona R. Identification of Shigella flexneri IcsA residues affecting interaction with N-WASP, and evidence for IcsA-IcsA co-operative interaction. PLoS One 2013; 8:e55152. [PMID: 23405119 PMCID: PMC3566212 DOI: 10.1371/journal.pone.0055152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 12/21/2012] [Indexed: 12/17/2022] Open
Abstract
The Shigella flexneri IcsA (VirG) protein is a polarly distributed outer membrane protein that is a fundamental virulence factor which interacts with neural Wiskott-Aldrich syndrome protein (N-WASP). The activated N-WASP then activates the Arp2/3 complex which initiates de novo actin nucleation and polymerisation to form F-actin comet tails and allows bacterial cell-to-cell spreading. In a previous study, IcsA was found to have three N-WASP interacting regions (IRs): IR I (aa 185-312), IR II (aa 330-382) and IR III (aa 508-730). The aim of this study was to more clearly define N-WASP interacting regions II and III by site-directed mutagenesis of specific amino acids. Mutant IcsA proteins were expressed in both smooth lipopolysaccharide (S-LPS) and rough LPS (R-LPS) S. flexneri strains and characterised for IcsA production level, N-WASP recruitment and F-actin comet tail formation. We have successfully identified new amino acids involved in N-WASP recruitment within different N-WASP interacting regions, and report for the first time using co-expression of mutant IcsA proteins, that N-WASP activation involves interactions with different regions on different IcsA molecules as shown by Arp3 recruitment. In addition, our findings suggest that autochaperone (AC) mutant protein production was not rescued by another AC region provided in trans, differing to that reported for two other autotransporters, PrtS and BrkA autotransporters.
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Affiliation(s)
- Min Yan Teh
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia
| | - Renato Morona
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia
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30
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Bruton's tyrosine kinase regulates Shigella flexneri dissemination in HT-29 intestinal cells. Infect Immun 2012; 81:598-607. [PMID: 23230296 DOI: 10.1128/iai.00853-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Shigella flexneri is a Gram-negative intracellular pathogen that infects the intestinal epithelium and utilizes actin-based motility to spread from cell to cell. S. flexneri actin-based motility has been characterized in various cell lines, but studies in intestinal cells are limited. Here we characterized S. flexneri actin-based motility in HT-29 intestinal cells. In agreement with studies conducted in various cell lines, we showed that S. flexneri relies on neural Wiskott-Aldrich Syndrome protein (N-WASP) in HT-29 cells. We tested the potential role of various tyrosine kinases involved in N-WASP activation and uncovered a previously unappreciated role for Bruton's tyrosine kinase (Btk) in actin tail formation in intestinal cells. We showed that Btk depletion led to a decrease in N-WASP phosphorylation which affected N-WASP recruitment to the bacterial surface, decreased the number of bacteria displaying actin-based motility, and ultimately affected the efficiency of spread from cell to cell. Finally, we showed that the levels of N-WASP phosphorylation and Btk expression were increased in response to infection, which suggests that S. flexneri infection not only triggers the production of proinflammatory factors as previously described but also manipulates cellular processes required for dissemination in intestinal cells.
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31
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May KL, Grabowicz M, Polyak SW, Morona R. Self-association of the Shigella flexneri IcsA autotransporter protein. MICROBIOLOGY-SGM 2012; 158:1874-1883. [PMID: 22516224 DOI: 10.1099/mic.0.056465-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The IcsA autotransporter protein is a major virulence factor of the human intracellular pathogen Shigella flexneri. IcsA is distributed at the poles in the outer membrane (OM) of S. flexneri and interacts with components of the host actin-polymerization machinery to facilitate intracellular actin-based motility and subsequent cell-to-cell spreading of the bacterium. We sought to characterize the biochemical properties of IcsA in the bacterial OM. Chemical cross-linking data suggested that IcsA exists in a complex in the OM. Furthermore, reciprocal co-immunoprecipitation of differentially epitope-tagged IcsA proteins indicated that IcsA is able to self-associate. The identification of IcsA linker-insertion mutants that were negatively dominant provided genetic evidence of IcsA-IcsA interactions. From these results, we propose a model whereby IcsA self-association facilitates efficient actin-based motility.
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Affiliation(s)
- Kerrie L May
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, South Australia, Australia
| | - Marcin Grabowicz
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, South Australia, Australia
| | - Steven W Polyak
- Discipline of Biochemistry, School of Molecular and Biomedical Science, University of Adelaide, South Australia, Australia
| | - Renato Morona
- Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, South Australia, Australia
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Mechanism of actin filament nucleation by the bacterial effector VopL. Nat Struct Mol Biol 2011; 18:1068-74. [PMID: 21873984 PMCID: PMC3168117 DOI: 10.1038/nsmb.2110] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 06/30/2011] [Indexed: 12/21/2022]
Abstract
Vibrio parahaemolyticus protein L (VopL) is an actin nucleation factor that induces stress fibers when injected by bacteria into eukaryotic host cells. VopL contains three N-terminal Wiskott-Aldrich Homology 2 (WH2) motifs and a unique VopL C-terminal domain (VCD). We describe crystallographic and biochemical analyses of filament nucleation by VopL. The WH2 element of VopL does not nucleate on its own, and requires the VCD for activity. The VCD forms a U-shaped dimer in the crystal, which is stabilized by a terminal coiled-coil. Dimerization of the WH2 motifs contributes strongly to nucleation activity, as do contacts of the VCD to actin. Our data lead to a model where VopL stabilizes primarily lateral (short-pitch) contacts between actin monomers to create the base of a two-stranded filament. Stabilization of lateral contacts may be a common feature of actin filament nucleation by WH2-based factors.
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Nusblat LM, Dovas A, Cox D. The non-redundant role of N-WASP in podosome-mediated matrix degradation in macrophages. Eur J Cell Biol 2011; 90:205-12. [DOI: 10.1016/j.ejcb.2010.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 07/07/2010] [Accepted: 07/15/2010] [Indexed: 10/25/2022] Open
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Isaac BM, Ishihara D, Nusblat LM, Gevrey JC, Dovas A, Condeelis J, Cox D. N-WASP has the ability to compensate for the loss of WASP in macrophage podosome formation and chemotaxis. Exp Cell Res 2010; 316:3406-16. [PMID: 20599953 DOI: 10.1016/j.yexcr.2010.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 06/09/2010] [Accepted: 06/10/2010] [Indexed: 10/24/2022]
Abstract
Wiskott-Aldrich syndrome protein (WASP) and its homologue neural-WASP (N-WASP) are nucleation promoting factors that integrate receptor signaling with actin cytoskeleton rearrangement. While hematopoietic cells express both WASP and N-WASP, WASP deficiency results in altered cell morphology, loss of podosomes and defective chemotaxis. It was determined that cells from a mouse derived monocyte/macrophage cell line and primary cells of myeloid lineage expressed approximately 15-fold higher levels of WASP relative to N-WASP. To test whether N-WASP can compensate for the loss of WASP and restore actin cytoskeleton integrity, N-WASP was overexpressed in macrophages, in which endogenous WASP expression was reduced by short hairpin RNA (shWASP cells). Many of the defects associated with the loss of WASP, such as podosome-dependent matrix degradation and chemotaxis were corrected when N-WASP was expressed at equimolar level to that of the wild-type WASP. Furthermore, the ability of N-WASP to partially compensate for the loss of WASP may be physiologically relevant since activated murine WASP-deficient peritoneal macrophages, which show enhanced N-WASP expression, also show an increase in matrix degradation. Our study suggests that expression levels of WASP and N-WASP may influence their roles in actin cytoskeleton rearrangement and shed light to the complex intertwining roles WASP and N-WASP play in macrophages.
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Affiliation(s)
- Beth M Isaac
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Activation of EGFR on monocytes is required for human cytomegalovirus entry and mediates cellular motility. Proc Natl Acad Sci U S A 2009; 106:22369-74. [PMID: 20018733 DOI: 10.1073/pnas.0908787106] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human cytomegalovirus (HCMV) rapidly induces a mobile and functionally unique proinflammatory monocyte following infection that is proposed to mediate viral spread. The cellular pathways used by HCMV to initiate these biological changes remain unknown. Here, we document the expression of the epidermal growth factor receptor (EGFR) on the surface of human peripheral blood monocytes but not on other blood leukocyte populations. Inhibition of EGFR signaling abrogated viral entry into monocytes, indicating that EGFR can serve as a cellular tropism receptor. Moreover, HCMV-activated EGFR was required for the induction of monocyte motility and transendothelial migration, two biological events required for monocyte extravasation into peripheral tissue, and thus viral spread. Transcriptome analysis revealed that HCMV-mediated EGFR signaling up-regulated neural Wiskott-Aldrich syndrome protein (N-WASP), an actin nucleator whose expression and function are normally limited in leukocytes. Knockdown of N-WASP expression blocked HCMV-induced but not phorbol 12-myristate 13-acetate (PMA)-induced monocyte motility, suggesting that a switch to and/or the distinct use of a new actin nucleator controlling motility occurs during HCMV infection of monocytes. Together, these data provide evidence that EGFR plays an essential role in the immunopathobiology of HCMV by mediating viral entry into monocytes and stimulating the aberrant biological activity that promotes hematogenous dissemination.
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Mutagenesis of the Shigella flexneri autotransporter IcsA reveals novel functional regions involved in IcsA biogenesis and recruitment of host neural Wiscott-Aldrich syndrome protein. J Bacteriol 2008; 190:4666-76. [PMID: 18456802 DOI: 10.1128/jb.00093-08] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The IcsA (VirG) protein of Shigella flexneri is a polarly localized, outer membrane protein that is essential for virulence. Within host cells, IcsA activates the host actin regulatory protein, neural Wiskott-Aldrich syndrome protein (N-WASP), which in turn recruits the Arp2/3 complex, which nucleates host actin to form F-actin comet tails and initiate bacterial motility. Linker insertion mutagenesis was undertaken to randomly introduce 5-amino-acid in-frame insertions within IcsA. Forty-seven linker insertion mutants were isolated and expressed in S. flexneri Delta icsA strains. Mutants were characterized for IcsA protein production, cell surface expression and localization, intercellular spreading, F-actin comet tail formation, and N-WASP recruitment. Using this approach, we have identified a putative autochaperone region required for IcsA biogenesis, and our data suggest an additional region, not previously identified, is required for N-WASP recruitment.
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Molecular pathogenesis of Shigella spp.: controlling host cell signaling, invasion, and death by type III secretion. Clin Microbiol Rev 2008; 21:134-56. [PMID: 18202440 DOI: 10.1128/cmr.00032-07] [Citation(s) in RCA: 400] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Shigella spp. are gram-negative pathogenic bacteria that evolved from harmless enterobacterial relatives and may cause devastating diarrhea upon ingestion. Research performed over the last 25 years revealed that a type III secretion system (T3SS) encoded on a large plasmid is a key virulence factor of Shigella flexneri. The T3SS determines the interactions of S. flexneri with intestinal cells by consecutively translocating two sets of effector proteins into the target cells. Thus, S. flexneri controls invasion into EC, intra- and intercellular spread, macrophage cell death, as well as host inflammatory responses. Some of the translocated effector proteins show novel biochemical activities by which they intercept host cell signal transduction pathways. An understanding of the molecular mechanisms underlying Shigella pathogenesis will foster the development of a safe and efficient vaccine, which, in parallel with improved hygiene, should curb infections by this widespread pathogen.
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Shinomiya H. [Dual role of the actin cytoskeleton in host defenses and in the establishment of bacterial infections]. Nihon Saikingaku Zasshi 2007; 62:279-93. [PMID: 17575795 DOI: 10.3412/jsb.62.279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Hiroto Shinomiya
- Department of Immunology and Host Defenses, Ehime University Graduate School of Medicine
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Jouvenet N, Windsor M, Rietdorf J, Hawes P, Monaghan P, Way M, Wileman T. African swine fever virus induces filopodia-like projections at the plasma membrane. Cell Microbiol 2006; 8:1803-11. [PMID: 16869831 DOI: 10.1111/j.1462-5822.2006.00750.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
When exiting the cell vaccinia virus induces actin polymerization and formation of a characteristic actin tail on the cytosolic face of the plasma membrane, directly beneath the extracellular particle. The actin tail acts to propel the virus away from the cell surface to enhance its cell-to-cell spread. We now demonstrate that African swine fever virus (ASFV), a member of the Asfarviridae family, also stimulates the polymerization of actin at the cell surface. Intracellular ASFV particles project out at the tip of long filopodia-like protrusions, at an average rate of 1.8 microm min(-1). Actin was arranged in long unbranched parallel arrays inside these virus-tipped projections. In contrast to vaccinia, this outward movement did not involve recruitment of Grb2, Nck1 or N-WASP. Actin polymerization was not nucleated by virus particles in transit to the cell periphery, and projections were not produced when the secretory pathway was disrupted by brefeldin A treatment. Our results show that when ASFV particles reach the plasma membrane they induce a localized nucleation of actin, and that this process requires interaction with virus-encoded and/or host proteins at the plasma membrane. We suggest that ASFV represents a valuable new model for studying pathways that regulate the formation of filopodia.
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Affiliation(s)
- Nolwenn Jouvenet
- Division of Immunology, Institute for Animal Health, Pirbright Laboratories, Ash Road, Woking, Surrey GU24 0NF, UK
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42
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Carlsson F, Brown EJ. Actin-based motility of intracellular bacteria, and polarized surface distribution of the bacterial effector molecules. J Cell Physiol 2006; 209:288-96. [PMID: 16826602 DOI: 10.1002/jcp.20721] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Several intracellular bacterial pathogens, including species of Listeria, Rickettsia, Shigella, Mycobacteria, and Burkholderia, have evolved mechanisms to exploit the actin polymerization machinery of their hosts to induce actin-based motility, enabling these pathogens to spread between host cells without exposing themselves to the extracellular milieu. Efficient cell-to-cell spread requires directional motility, which the bacteria may achieve by concentrating the effector molecules at one pole of their cell body, thereby restricting polymerization of monomeric actin into actin tails to this pole. The study of the molecular processes involved in the initiation of actin tail formation at the bacterial surface, and subsequent actin-based motility, has provided much insight into the pathogenesis of infections caused by these bacteria and into the cell biology of actin dynamics. Concomitantly, this field of research has provided an opportunity to understand the mechanisms whereby bacteria can achieve a polarized distribution of surface proteins. This review will describe the process of actin-based motility of intracellular bacteria, and the mechanisms by which bacteria can obtain a polarized distribution of their surface proteins.
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Affiliation(s)
- Fredric Carlsson
- Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, California 94158-2517, USA.
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Hayward RD, Leong JM, Koronakis V, Campellone KG. Exploiting pathogenic Escherichia coli to model transmembrane receptor signalling. Nat Rev Microbiol 2006; 4:358-70. [PMID: 16582930 DOI: 10.1038/nrmicro1391] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Many microbial pathogens manipulate the actin cytoskeleton of eukaryotic target cells to promote their internalization, intracellular motility and dissemination. Enteropathogenic and enterohaemorrhagic Escherichia coli, which both cause severe diarrhoeal disease, can adhere to mammalian intestinal cells and induce reorganization of the actin cytoskeleton into 'pedestal-like' pseudopods beneath the extracellular bacteria. As pedestal assembly is triggered by E. coli virulence factors that mimic several host cell-signalling components, such as transmembrane receptors, their cognate ligands and cytoplasmic adaptor proteins, it can serve as a powerful model system to study eukaryotic transmembrane signalling. Here, we consider the impact of recent data on our understanding of both E. coli pathogenesis and cell biology, and the rich prospects for exploiting these bacterial factors as versatile tools to probe cellular signalling pathways.
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Affiliation(s)
- Richard D Hayward
- University of Cambridge, Department of Pathology, Tennis Court Road, Cambridge CB2 1QP, UK
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Suzuki S, Oshima K, Kakizawa S, Arashida R, Jung HY, Yamaji Y, Nishigawa H, Ugaki M, Namba S. Interaction between the membrane protein of a pathogen and insect microfilament complex determines insect-vector specificity. Proc Natl Acad Sci U S A 2006; 103:4252-7. [PMID: 16537517 PMCID: PMC1449679 DOI: 10.1073/pnas.0508668103] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many insect-transmissible pathogens are transmitted by specific insect species and not by others, even if they are closely related. The molecular mechanisms underlying such strict pathogen-insect specificity are poorly understood. Candidatus Phytoplasma asteris, OY strain, line W (OY), is a phytopathogenic bacterium transmitted from plant to plant by sap-feeding insect vectors (leafhoppers). Our study focused on an abundant cell-surface membrane protein of the phytoplasma named antigenic membrane protein (Amp), which is not homologous with any reported functional protein. Immunofluorescence microscopy of the phytoplasma-infected insect showed that OY phytoplasma was localized to the microfilaments of the visceral smooth muscle surrounding the insect's intestinal tract. The affinity column assay showed that Amp forms a complex with three insect proteins: actin, myosin heavy chain, and myosin light chain. Amp-microfilament complexes were detected in all OY-transmitting leafhopper species, but not in the non-OY-transmitting leafhoppers, suggesting that the formation of the Amp-microfilament complex is correlated with the phytoplasma-transmitting capability of leafhoppers. Although several studies have reported interactions between pathogens and mammalian microfilaments, this is an example of host-specific interactions between a bacterial surface protein and a host microfilament in insect cells. Our data also suggest that the utilization of a host microfilament may be a universal system for pathogenic bacteria infecting mammals or insects.
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Affiliation(s)
- Shiho Suzuki
- *Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; and
| | - Kenro Oshima
- *Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; and
| | - Shigeyuki Kakizawa
- *Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; and
| | - Ryo Arashida
- *Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; and
| | - Hee-Young Jung
- *Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; and
| | - Yasuyuki Yamaji
- *Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; and
| | - Hisashi Nishigawa
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Masashi Ugaki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
| | - Shigetou Namba
- *Laboratory of Plant Pathology, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; and
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562, Japan
- To whom correspondence should be addressed. E-mail:
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Kheir WA, Gevrey JC, Yamaguchi H, Isaac B, Cox D. A WAVE2-Abi1 complex mediates CSF-1-induced F-actin-rich membrane protrusions and migration in macrophages. J Cell Sci 2006; 118:5369-79. [PMID: 16280551 DOI: 10.1242/jcs.02638] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Colony-stimulating factor 1 (CSF-1) is an important physiological chemoattractant for macrophages. The mechanisms by which CSF-1 elicits the formation of filamentous actin (F-actin)-rich membrane protrusions and induces macrophage migration are not fully understood. In particular, very little is known regarding the contribution of the different members of the Wiskott-Aldrich Syndrome protein (WASP) family of actin regulators in response to CSF-1. Although a role for WASP itself in macrophage chemotaxis has been previously identified, no data was available regarding the function of WASP family verprolin-homologous (WAVE) proteins in this cell type. We found that WAVE2 was the predominant isoform to be expressed in primary macrophages and in cells derived from the murine monocyte/macrophage RAW264.7 cell line (RAW/LR5). CSF-1 treatment of macrophages resulted in WAVE2 accumulation in F-actin-rich protrusions induced by CSF-1. Inhibition of WAVE2 function by expressing a dominant-negative mutant or introducing anti-WAVE2 antibodies in RAW/LR5 cells, as well as reduction of endogenous WAVE2 expression by RNA-mediated interference (RNAi), resulted in a significant reduction of CSF-1-elicited F-actin protrusions. WAVE2 was found in a protein complex together with Abelson kinase interactor 1 (Abi1) in resting or stimulated cells. Both WAVE2 and Abi1 were recruited to and necessary for the formation of F-actin protrusions in response to CSF-1. Reducing the levels of WAVE2, directly or by targeting Abi1, resulted in an impaired cell migration to CSF-1. Altogether these data identify a WAVE2-Abi1 complex crucial for the normal actin cytoskeleton reorganization and migration of macrophages in response to CSF-1.
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Affiliation(s)
- Wassim Abou Kheir
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York City, NY 10461, USA
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46
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Abstract
Listeria, Rickettsia, Burkholderia, Shigella and Mycobacterium species subvert cellular actin dynamics to facilitate their movement within the host cytosol and to infect neighbouring cells while evading host immune surveillance and promoting their intracellular survival. 'Attaching and effacing' Escherichia coli do not enter host cells but attach intimately to the cell surface, inducing motile actin-rich pedestals, the function of which is currently unclear. The molecular basis of actin-based motility of these bacterial pathogens reveals novel insights about bacterial pathogenesis and fundamental host-cell pathways.
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Affiliation(s)
- Joanne M Stevens
- Division of Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire, RG20 7NN, UK
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Parsot C. Shigellaspp. and enteroinvasiveEscherichia colipathogenicity factors. FEMS Microbiol Lett 2005; 252:11-8. [PMID: 16182469 DOI: 10.1016/j.femsle.2005.08.046] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 08/17/2005] [Indexed: 10/25/2022] Open
Abstract
Bacteria of Shigella spp. (S. boydii, S. dysenteriae, S. flexneri and S. sonnei) and enteroinvasive Escherichia coli (EIEC) are responsible for shigellosis in humans, a disease characterized by the destruction of the colonic mucosa that is induced upon bacterial invasion. Shigella spp. and EIEC strains contain a virulence plasmid of approximately 220 kb that encodes determinants for entry into epithelial cells and dissemination from cell to cell. This review presents the current model on mechanisms of invasion of the colonic epithelium by these bacteria and focuses on their pathogenicity factors, particularly the virulence plasmid-encoded type III secretion system.
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Affiliation(s)
- Claude Parsot
- Unité de Pathogénie Microbienne Moléculaire, INSERM U389, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France.
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Stamm LM, Pak MA, Morisaki JH, Snapper SB, Rottner K, Lommel S, Brown EJ. Role of the WASP family proteins for Mycobacterium marinum actin tail formation. Proc Natl Acad Sci U S A 2005; 102:14837-42. [PMID: 16199520 PMCID: PMC1239894 DOI: 10.1073/pnas.0504663102] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium marinum, a natural pathogen of fish and frogs and an occasional pathogen of humans, is capable of inducing actin tail formation within the cytoplasm of macrophages, leading to actin-based motility and intercellular spread. Actin tail formation by M. marinum is markedly reduced in macrophages deficient in the Wiskott-Aldrich syndrome protein (WASP), which still contain the closely related and ubiquitously expressed protein N-WASP (neuronal WASP). In fibroblasts lacking both WASP and N-WASP, M. marinum is incapable of efficient actin polymerization and of intercellular spread. By reconstituting these cells, we find that M. marinum is able to use either WASP or N-WASP to induce actin polymerization. Inhibition or genetic deletion of tyrosine phosphorylation, Nck, WASP-interacting protein, and Cdc42 does not affect M. marinum actin tail formation, excluding the participation of these molecules as upstream activators of N-WASP in the initiation of actin-based motility. In contrast, deletion of the phosphatidylinositol 4,5-bisphosphate-binding basic motif in N-WASP eliminates M. marinum actin tail formation. Together, these data demonstrate that M. marinum subversion of host actin polymerization is most similar to distantly related Gram-negative organisms but that its mechanism for activating WASP family proteins is unique.
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Affiliation(s)
- Luisa M Stamm
- Program in Microbial Pathogenesis and Host Defense, University of California, San Francisco, CA 94143, USA
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Guerra S, Aracil M, Conde R, Bernad A, Esteban M. Wiskott-Aldrich syndrome protein is needed for vaccinia virus pathogenesis. J Virol 2005; 79:2133-40. [PMID: 15681416 PMCID: PMC546576 DOI: 10.1128/jvi.79.4.2133-2140.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Smallpox, caused by variola virus, was a devastating disease in humans, but how the virus evolved a strategy to spread to tissue remains unknown. Through the use of microarrays, we identified the gene encoding the Wiskott-Aldrich syndrome protein (WASP), one of the five known WASP family members, which has been induced in the course of infection of human cells with different strains of vaccinia virus (VV) (S. Guerra, L. A. Lopez-Fernandez, A. Pascual-Montano, M. Munoz, K. Harshman, and M. Esteban, J. Virol. 77:6493-6506, 2003; S. Guerra, L. A. Lopez-Fernandez, R. Conde, A. Pascual-Montano, K. Harshman, and M. Esteban, J. Virol. 78:5820-5834, 2004). In a mouse model, we evaluated the role of WASP in infection with VV, a close relative of variola virus. WASP(-/-) (KO) mice infected intranasally and intraperitoneally with VV showed reduced weight loss and mortality compared to wild-type (WT) mice. WASP expression correlated with VV replication in the ovaries but not in the liver or spleen. WT mouse macrophages express WASP but not N-WASP; after VV infection, WASP levels increase threefold. KO macrophages lack N-WASP expression and, when VV infected, are incapable of inducing actin tails and producing extracellular virus. These functions were rescued in KO macrophages after ectopic WASP expression. Overall, our findings demonstrate that WASP has a role in orthopoxvirus infections. Use of WASP proteins for virus spread via the actin tail provides a selective advantage for VV, and probably variola virus, dissemination to distant tissues.
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Affiliation(s)
- Susana Guerra
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Campus Universidad Autónoma, 28049 Madrid, Spain
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Abstract
The actin cytoskeleton is harnessed by several pathogenic bacteria that are capable of entering into non-phagocytic cells, the so-called 'invasive bacteria'. Among them, a few also exploit the host actin cytoskeleton to move intra- and inter-cellularly. Our knowledge of the basic mechanisms underlying actin-based motility has dramatically increased and the list of bacteria that are able to move in this way is also increasing including not only Listeria, Shigella and Rickettsia species but also Mycobacterium marinum and Burkholderia pseudomallei. In all cases the central player is the Arp2/3 complex. Vaccinia virus moves intracellularly on microtubules and just after budding, triggers actin polymerization and the formation of protrusions similar to that of adherent enteropathogenic Escherichia coli, that involve the Arp2/3 complex and facilitate its inter-cellular spread.
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Affiliation(s)
- Edith Gouin
- Unité des Interactions Bactéries-cellules, Institut Pasteur, 28 Rue du Docteur Roux, Paris 75015, France
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