1
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Raab JE, Hamilton DJ, Harju TB, Huynh TN, Russo BC. Pushing boundaries: mechanisms enabling bacterial pathogens to spread between cells. Infect Immun 2024:e0052423. [PMID: 38661369 DOI: 10.1128/iai.00524-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024] Open
Abstract
For multiple intracellular bacterial pathogens, the ability to spread directly into adjacent epithelial cells is an essential step for disease in humans. For pathogens such as Shigella, Listeria, Rickettsia, and Burkholderia, this intercellular movement frequently requires the pathogens to manipulate the host actin cytoskeleton and deform the plasma membrane into structures known as protrusions, which extend into neighboring cells. The protrusion is then typically resolved into a double-membrane vacuole (DMV) from which the pathogen quickly escapes into the cytosol, where additional rounds of intercellular spread occur. Significant progress over the last few years has begun to define the mechanisms by which intracellular bacterial pathogens spread. This review highlights the interactions of bacterial and host factors that drive mechanisms required for intercellular spread with a focus on how protrusion structures form and resolve.
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Affiliation(s)
- Julie E Raab
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Desmond J Hamilton
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Tucker B Harju
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Thao N Huynh
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Brian C Russo
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
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2
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Hall CP, Jadeja NB, Sebeck N, Agaisse H. Characterization of MxiE- and H-NS-Dependent Expression of ipaH7.8, ospC1, yccE, and yfdF in Shigella flexneri. mSphere 2022; 7:e0048522. [PMID: 36346241 PMCID: PMC9769918 DOI: 10.1128/msphere.00485-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 10/10/2022] [Indexed: 11/09/2022] Open
Abstract
Shigella flexneri uses a type 3 secretion system (T3SS) apparatus to inject virulence effector proteins into the host cell cytosol. Upon host cell contact, MxiE, an S. flexneri AraC-like transcriptional regulator, is required for the expression of a subset of T3SS effector genes encoded on the large virulence plasmid. Here, we defined the MxiE regulon using RNA-seq. We identified virulence plasmid- and chromosome-encoded genes that are activated in response to type 3 secretion in a MxiE-dependent manner. Bioinformatic analysis revealed that similar to previously known MxiE-dependent genes, chromosome-encoded genes yccE and yfdF contain a regulatory element known as the MxiE box, which is required for their MxiE-dependent expression. The significant AT enrichment of MxiE-dependent genes suggested the involvement of H-NS. Using a dominant negative H-NS system, we demonstrate that H-NS silences the expression of MxiE-dependent genes located on the virulence plasmid (ipaH7.8 and ospC1) and the chromosome (yccE and yfdF). Furthermore, we show that MxiE is no longer required for the expression of ipaH7.8, ospC1, yccE, and yfdF when H-NS silencing is relieved. Finally, we show that the H-NS anti-silencer VirB is not required for ipaH7.8 and yccE expression upon MxiE/IpgC overexpression. Based on these genetic studies, we propose a model of MxiE-dependent gene regulation in which MxiE counteracts H-NS-mediated silencing. IMPORTANCE The expression of horizontally acquired genes, including virulence genes, is subject to complex regulation involving xenogeneic silencing proteins, and counter-silencing mechanisms. The pathogenic properties of Shigella flexneri mainly rely on the acquisition of the type 3 secretion system (T3SS) and cognate effector proteins, whose expression is repressed by the xenogeneic silencing protein H-NS. Based on previous studies, releasing H-NS-mediated silencing mainly relies on two mechanisms involving (i) a temperature shift leading to the release of H-NS at the virF promoter, and (ii) the virulence factor VirB, which dislodges H-NS upon binding to specific motifs upstream of virulence genes, including those encoding the T3SS. In this study, we provide genetic evidence supporting the notion that, in addition to VirB, the AraC family member MxiE also contributes to releasing H-NS-mediated silencing in S. flexneri.
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Affiliation(s)
- Chelsea P. Hall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Niti B. Jadeja
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Natalie Sebeck
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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3
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The Chlamydia trachomatis Inclusion Membrane Protein CTL0390 Mediates Host Cell Exit via Lysis through STING Activation. Infect Immun 2022; 90:e0019022. [PMID: 35587198 DOI: 10.1128/iai.00190-22] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The obligate intracellular bacterium Chlamydia trachomatis is the causative agent of the most frequently reported bacterial sexually transmitted disease. Upon internalization into host cells, C. trachomatis remains within a membrane-bound compartment known as an inclusion, where it undergoes its developmental cycle. After completion of this cycle, bacteria exit the host cell. One mechanism of exit is lysis, whereby the inclusion and host cell rupture to release bacteria; however, the mechanism of lysis is not well characterized. A subset of C. trachomatis effectors, known as inclusion membrane proteins (Inc), are embedded within the inclusion membrane to facilitate host cell manipulation. The functions of many Inc proteins are unknown. We sought to characterize the Inc protein CTL0390. We determined that CTL0390 is expressed throughout the developmental cycle and that its C-terminal tail is exposed to the cytosol. To investigate the function of CTL0390, we generated a ctl0390 mutant complemented with ctl0390 on a plasmid. Loss of CTL0390 did not affect infectious progeny production but resulted in a reduction in lysis. Overexpression of CTL0390 induced premature lysis and host nuclear condensation, the latter of which could be reduced upon inhibition of the cGAS-STING DNA sensing pathway. Infection with the clt0390 mutant led to reduced Golgi translocation of STING, and chemical and genetic approaches to inactivate STING revealed that STING plays a role in lysis in a CTL0390-dependent manner. Together, these results reveal a role for CTL0390 in bacterial exit via lysis at late stages of the Chlamydia developmental cycle and through STING activation.
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4
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Köseoğlu VK, Jones MK, Agaisse H. The type 3 secretion effector IpgD promotes S. flexneri dissemination. PLoS Pathog 2022; 18:e1010324. [PMID: 35130324 PMCID: PMC8853559 DOI: 10.1371/journal.ppat.1010324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 02/17/2022] [Accepted: 01/31/2022] [Indexed: 12/15/2022] Open
Abstract
The bacterial pathogen Shigella flexneri causes 270 million cases of bacillary dysentery worldwide every year, resulting in more than 200,000 deaths. S. flexneri pathogenic properties rely on its ability to invade epithelial cells and spread from cell to cell within the colonic epithelium. This dissemination process relies on actin-based motility in the cytosol of infected cells and formation of membrane protrusions that project into adjacent cells and resolve into double-membrane vacuoles (DMVs) from which the pathogen escapes, thereby achieving cell-to-cell spread. S. flexneri dissemination is facilitated by the type 3 secretion system (T3SS) through poorly understood mechanisms. Here, we show that the T3SS effector IpgD facilitates the resolution of membrane protrusions into DMVs during S. flexneri dissemination. The phosphatidylinositol 4-phosphatase activity of IpgD decreases PtdIns(4,5)P2 levels in membrane protrusions, thereby counteracting de novo cortical actin formation in protrusions, a process that restricts the resolution of protrusions into DMVs. Finally, using an infant rabbit model of shigellosis, we show that IpgD is required for efficient cell-to-cell spread in vivo and contributes to the severity of dysentery. The intracellular pathogen Shigella flexneri is the causative agent of bacillary dysentery (blood in stool). Invasion of epithelial cells and cell-to-cell spread are critical determinants of S. flexneri pathogenesis. Cell-to-cell spread relies on the formation of membrane protrusions that project into adjacent cells and resolve into vacuoles. The molecular mechanisms supporting this dissemination process are poorly understood. In this study, we show that S. flexneri employs the phosphatidylinositol phosphatase activity of the T3SS effector protein IpgD to manipulate phosphoinositides in the protrusion membrane. Manipulation of phosphoinositide signaling restricts the formation of actin networks underneath the protrusion membrane, which would otherwise prevent the scission of protrusions into vacuoles. We also demonstrate that IpgD is required for efficient dissemination in the colon of infant rabbits and contributes to the severity of disease. This study exemplifies how manipulation of phosphoinositide signaling by intracellular pathogens supports bacterial pathogenesis.
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Affiliation(s)
- Volkan K. Köseoğlu
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, Charlottesville, Virginia, United States of America
| | - Marieke K. Jones
- Claude Moore Health Sciences Library, University of Virginia, Charlottesville, Virginia, United States of America
| | - Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer Biology, School of Medicine, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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5
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The type three secretion system effector protein IpgB1 promotes Shigella flexneri cell-to-cell spread through double-membrane vacuole escape. PLoS Pathog 2022; 18:e1010380. [PMID: 35202448 PMCID: PMC8903249 DOI: 10.1371/journal.ppat.1010380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/08/2022] [Accepted: 02/18/2022] [Indexed: 12/11/2022] Open
Abstract
S. flexneri is an important human pathogen that causes bacillary dysentery. During infection, S. flexneri invades colonic epithelial cells, hijacks the host cell cytoskeleton to move in the cytosol of infected cells, and spreads from cell to cell through formation of membrane protrusions that project into adjacent cells and resolve into double membrane vacuoles (DMVs). S. flexneri cell-to-cell spread requires the integrity of the bacterial type three secretion system (T3SS). However, the exact role of the T3SS effector proteins in the dissemination process remains poorly understood. Here, we investigated the role of the T3SS effector protein IpgB1 in S. flexneri dissemination. IpgB1 was previously characterized as a guanine nucleotide exchange factor (GEF) that contributes to invasion. In addition to the invasion defect, we showed that the ipgB1 mutant formed smaller infection foci in HT-29 cells. Complementation of this phenotype required the GEF activity of IpgB1. Using live confocal microscopy, we showed that the ipgB1 mutant is specifically impaired in DMV escape. Depletion of Rac1, the host cell target of IpgB1 during invasion, as well as pharmacological inhibition of Rac1 signaling, reduced cell-to-cell spread and DMV escape. In a targeted siRNA screen, we uncovered that RhoA depletion restored ipgB1 cell-to-cell spread and DMV escape, revealing a critical role for the IpgB1-Rac1 axis in antagonizing RhoA-mediated restriction of DMV escape. Using an infant rabbit model of shigellosis, we showed that the ipgB1 mutant formed fewer and smaller infection foci in the colon of infected animals, which correlated with attenuated symptoms of disease, including epithelial fenestration and bloody diarrhea. Our results demonstrate that, in addition to its role during invasion, IpgB1 modulates Rho family small GTPase signaling to promote cell-to-cell spread, DMV escape, and S. flexneri pathogenesis.
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6
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Herath TUB, Roy A, Gianfelice A, Ireton K. Shigella flexneri subverts host polarized exocytosis to enhance cell-to-cell spread. Mol Microbiol 2021; 116:1328-1346. [PMID: 34608697 DOI: 10.1111/mmi.14827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 09/21/2021] [Accepted: 10/01/2021] [Indexed: 11/28/2022]
Abstract
Shigella flexneri is a gram-negative bacterial pathogen that causes dysentery. Critical for disease is the ability of Shigella to use an actin-based motility (ABM) process to spread between cells of the colonic epithelium. ABM transports bacteria to the periphery of host cells, allowing the formation of plasma membrane protrusions that mediate spread to adjacent cells. Here we demonstrate that efficient protrusion formation and cell-to-cell spread of Shigella involves bacterial stimulation of host polarized exocytosis. Using an exocytic probe, we found that exocytosis is locally upregulated in bacterial protrusions in a manner that depends on the Shigella type III secretion system. Experiments involving RNA interference (RNAi) indicate that efficient bacterial protrusion formation and spread require the exocyst, a mammalian multi-protein complex known to mediate polarized exocytosis. In addition, the exocyst component Exo70 and the exocyst regulator RalA were recruited to Shigella protrusions, suggesting that bacteria manipulate exocyst function. Importantly, RNAi-mediated depletion of exocyst proteins or RalA reduced the frequency of protrusion formation and also the lengths of protrusions, demonstrating that the exocyst controls both the initiation and elongation of protrusions. Collectively, our results reveal that Shigella co-opts the exocyst complex to disseminate efficiently in host cell monolayers.
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Affiliation(s)
- Thilina U B Herath
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Arpita Roy
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Antonella Gianfelice
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Keith Ireton
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
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7
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Dowd GC, Mortuza R, Ireton K. Molecular Mechanisms of Intercellular Dissemination of Bacterial Pathogens. Trends Microbiol 2020; 29:127-141. [PMID: 32682632 DOI: 10.1016/j.tim.2020.06.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/23/2020] [Accepted: 06/25/2020] [Indexed: 02/07/2023]
Abstract
Several intracellular bacterial pathogens, including Listeria monocytogenes, Shigella flexerni, and Rickettsia spp. use an actin-based motility process to spread in mammalian cell monolayers. Cell-to-cell spread is mediated by protrusive structures that contain bacteria encased in the host cell plasma membrane. These protrusions, which form in infected host cells, are internalized by neighboring cells. In this review, we summarize key findings on cell-to-cell spread, focusing on recent work on mechanisms of protrusion formation and internalization. We also discuss the dynamic behavior of bacterial populations during spread, and highlight recent findings showing that intercellular spread by an extracellular bacterial pathogen.
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Affiliation(s)
- Georgina C Dowd
- Department of Microbiology and Immunology, University of Otago, Dunedin 9054, New Zealand
| | - Roman Mortuza
- Department of Microbiology and Immunology, University of Otago, Dunedin 9054, New Zealand
| | - Keith Ireton
- Department of Microbiology and Immunology, University of Otago, Dunedin 9054, New Zealand.
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8
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Walpole GFW, Grinstein S. Endocytosis and the internalization of pathogenic organisms: focus on phosphoinositides. F1000Res 2020; 9. [PMID: 32494357 PMCID: PMC7233180 DOI: 10.12688/f1000research.22393.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/07/2020] [Indexed: 12/18/2022] Open
Abstract
Despite their comparatively low abundance in biological membranes, phosphoinositides are key to the regulation of a diverse array of signaling pathways and direct membrane traffic. The role of phosphoinositides in the initiation and progression of endocytic pathways has been studied in considerable depth. Recent advances have revealed that distinct phosphoinositide species feature prominently in clathrin-dependent and -independent endocytosis as well as in phagocytosis and macropinocytosis. Moreover, a variety of intracellular and cell-associated pathogens have developed strategies to commandeer host cell phosphoinositide metabolism to gain entry and/or metabolic advantage, thereby promoting their survival and proliferation. Here, we briefly survey the current knowledge on the involvement of phosphoinositides in endocytosis, phagocytosis, and macropinocytosis and highlight several examples of molecular mimicry employed by pathogens to either “hitch a ride” on endocytic pathways endogenous to the host or create an entry path of their own.
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Affiliation(s)
- Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre of the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
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9
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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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10
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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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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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Chen J, Xing C, Yan L, Wang Y, Wang H, Zhang Z, Yu D, Li J, Li H, Li J, Cai Y. Transcriptome profiling reveals the role of ZBTB38 knock-down in human neuroblastoma. PeerJ 2019; 7:e6352. [PMID: 30697495 PMCID: PMC6348090 DOI: 10.7717/peerj.6352] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 12/27/2018] [Indexed: 12/11/2022] Open
Abstract
ZBTB38 belongs to the zinc finger protein family and contains the typical BTB domains. As a transcription factor, ZBTB38 is involved in cell regulation, proliferation and apoptosis, whereas, functional deficiency of ZBTB38 induces the human neuroblastoma (NB) cell death potentially. To have some insight into the role of ZBTB38 in NB development, high throughput RNA sequencing was performed using the human NB cell line SH-SY5Y with the deletion of ZBTB38. In the present study, 2,438 differentially expressed genes (DEGs) in ZBTB38−/− SH-SY5Y cells were obtained, 83.5% of which was down-regulated. Functional annotation of the DEGs in the Kyoto Encyclopedia of Genes and Genomes database revealed that most of the identified genes were enriched in the neurotrophin TRK receptor signaling pathway, including PI3K/Akt and MAPK signaling pathway. we also observed that ZBTB38 affects expression of CDK4/6, Cyclin E, MDM2, ATM, ATR, PTEN, Gadd45, and PIGs in the p53 signaling pathway. In addition, ZBTB38 knockdown significantly suppresses the expression of autophagy-related key genes including PIK3C2A and RB1CC1. The present meeting provides evidence to molecular mechanism of ZBTB38 modulating NB development and targeted anti-tumor therapies.
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Affiliation(s)
- Jie Chen
- College of Life Sciences, Anhui Provincial Key Lab of the Conservation and Exploitation of Biological Resources, Anhui Normal University, WuHu, China.,College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China.,The Secondary Hospital of Wuhu, WuHu, China
| | - Chaofeng Xing
- College of Life Sciences, Anhui Provincial Key Lab of the Conservation and Exploitation of Biological Resources, Anhui Normal University, WuHu, China.,College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Li Yan
- Department of Radiation Oncology, Linyi People Hospital, Linyi, China
| | - Yabing Wang
- The First Affiliated Hospital of Wannan Medical College, WuHu, China
| | | | - Zongmeng Zhang
- College of Life Sciences, Anhui Provincial Key Lab of the Conservation and Exploitation of Biological Resources, Anhui Normal University, WuHu, China
| | - Daolun Yu
- College of Life Sciences, Anhui Provincial Key Lab of the Conservation and Exploitation of Biological Resources, Anhui Normal University, WuHu, China
| | - Jie Li
- College of Life Sciences, Anhui Provincial Key Lab of the Conservation and Exploitation of Biological Resources, Anhui Normal University, WuHu, China
| | - Honglin Li
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta State University, Augusta, GA, USA
| | - Jun Li
- College of Life Sciences, Anhui Provincial Key Lab of the Conservation and Exploitation of Biological Resources, Anhui Normal University, WuHu, China
| | - Yafei Cai
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China
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13
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Affiliation(s)
- Erin Weddle
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Hervé Agaisse
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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14
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Spatial, Temporal, and Functional Assessment of LC3-Dependent Autophagy in Shigella flexneri Dissemination. Infect Immun 2018; 86:IAI.00134-18. [PMID: 29844234 DOI: 10.1128/iai.00134-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/22/2018] [Indexed: 12/21/2022] Open
Abstract
Shigella flexneri disseminates within the colonic mucosa by displaying actin-based motility in the cytosol of epithelial cells. Motile bacteria form membrane protrusions that project into adjacent cells and resolve into double-membrane vacuoles (DMVs) from which the bacteria escape, thereby achieving cell-to-cell spread. During dissemination, S. flexneri is targeted by LC3-dependent autophagy, a host cell defense mechanism against intracellular pathogens. The S. flexneri type III secretion system effector protein IcsB was initially proposed to counteract the recruitment of the LC3-dependent autophagy machinery to cytosolic bacteria. However, a recent study proposed that LC3 was recruited to bacteria in DMVs formed during cell-to-cell spread. To resolve the controversy and clarify the role of autophagy in S. flexneri infection, we tracked dissemination using live confocal microscopy and determined the spatial and temporal recruitment of LC3 to bacteria. This approach demonstrated that (i) LC3 was exclusively recruited to wild-type or icsB bacteria located in DMVs and (ii) the icsB mutant was defective in cell-to-cell spread due to failure to escape LC3-positive as well as LC3-negative DMVs. Failure of S. flexneri to escape DMVs correlated with late LC3 recruitment, suggesting that LC3 recruitment is the consequence and not the cause of DMV escape failure. Inhibition of autophagy had no positive impact on the spreading of wild-type or icsB mutant bacteria. Our results unambiguously demonstrate that IcsB is required for DMV escape during cell-to-cell spread, regardless of LC3 recruitment, and do not support the previously proposed notion that autophagy counters S. flexneri dissemination.
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15
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Qiu S, Côté M. From hitchhiker to hijacker: pathogen exploitation of endosomal phosphoinositides 1. Biochem Cell Biol 2018; 97:1-9. [PMID: 29746785 DOI: 10.1139/bcb-2017-0317] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Signalling through phosphoinositide lipids is essential for regulating many cellular processes, including endosomal trafficking. A number of intracellular pathogens have found ways to subvert host trafficking pathways via exploitation of endosomal phosphoinositides. This review will discuss how pathogens such as bacteria, viruses, and eukaryotic parasites depend on endosomal phosphoinositides for infection as well as the mechanisms through which some are able to actively manipulate these signalling lipids to facilitate invasion, survival, replication, and immune evasion.
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Affiliation(s)
- Shirley Qiu
- a Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,b Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,c Center for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Marceline Côté
- a Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,b Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,c Center for Infection, Immunity and Inflammation, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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16
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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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17
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Lamason RL, Welch MD. Actin-based motility and cell-to-cell spread of bacterial pathogens. Curr Opin Microbiol 2016; 35:48-57. [PMID: 27997855 DOI: 10.1016/j.mib.2016.11.007] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 11/29/2016] [Accepted: 11/30/2016] [Indexed: 12/17/2022]
Abstract
Subversion of the host actin cytoskeleton is a critical virulence mechanism used by a variety of intracellular bacterial pathogens during their infectious life cycles. These pathogens manipulate host actin to promote actin-based motility and coordinate motility with cell-to-cell spread. Growing evidence suggests that the tactics employed by pathogens are surprisingly diverse. Here, we review recent advances suggesting that bacterial surface proteins exhibit divergent biochemical mechanisms of actin polymerization and recruit distinct host protein networks to drive motility, and that bacteria deploy secreted effector proteins that alter host cell mechanotransduction pathways to enable spread. Further investigation into the divergent strategies used by bacterial pathogens to mobilize actin will reveal new insights into pathogenesis and cytoskeleton regulation.
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Affiliation(s)
- Rebecca L Lamason
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
| | - Matthew D Welch
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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18
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Lamason RL, Bastounis E, Kafai NM, Serrano R, Del Álamo JC, Theriot JA, Welch MD. Rickettsia Sca4 Reduces Vinculin-Mediated Intercellular Tension to Promote Spread. Cell 2016; 167:670-683.e10. [PMID: 27768890 DOI: 10.1016/j.cell.2016.09.023] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 07/22/2016] [Accepted: 09/13/2016] [Indexed: 12/12/2022]
Abstract
Spotted fever group (SFG) rickettsiae are human pathogens that infect cells in the vasculature. They disseminate through host tissues by a process of cell-to-cell spread that involves protrusion formation, engulfment, and vacuolar escape. Other bacterial pathogens rely on actin-based motility to provide a physical force for spread. Here, we show that SFG species Rickettsia parkeri typically lack actin tails during spread and instead manipulate host intercellular tension and mechanotransduction to promote spread. Using transposon mutagenesis, we identified surface cell antigen 4 (Sca4) as a secreted effector of spread that specifically promotes protrusion engulfment. Sca4 interacts with the cell-adhesion protein vinculin and blocks association with vinculin's binding partner, α-catenin. Using traction and monolayer stress microscopy, we show that Sca4 reduces vinculin-dependent mechanotransduction at cell-cell junctions. Our results suggest that Sca4 relieves intercellular tension to promote protrusion engulfment, which represents a distinctive strategy for manipulating cytoskeletal force generation to enable spread.
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Affiliation(s)
- Rebecca L Lamason
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Effie Bastounis
- Departments of Biochemistry, Microbiology, and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Natasha M Kafai
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ricardo Serrano
- Mechanical and Aerospace Engineering Department, University of California, San Diego, La Jolla, CA 92093, USA
| | - Juan C Del Álamo
- Mechanical and Aerospace Engineering Department, University of California, San Diego, La Jolla, CA 92093, USA; Institute for Engineering in Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Julie A Theriot
- Departments of Biochemistry, Microbiology, and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Matthew D Welch
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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The Metalloprotease Mpl Supports Listeria monocytogenes Dissemination through Resolution of Membrane Protrusions into Vacuoles. Infect Immun 2016; 84:1806-1814. [PMID: 27068088 DOI: 10.1128/iai.00130-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 04/01/2016] [Indexed: 11/20/2022] Open
Abstract
Listeria monocytogenes is an intracellular pathogen that disseminates within the intestinal epithelium through acquisition of actin-based motility and formation of plasma membrane protrusions that project into adjacent cells. The resolution of membrane protrusions into vacuoles from which the pathogen escapes results in bacterial spread from cell to cell. This dissemination process relies on the mlp-actA-plcB operon, which encodes ActA, a bacterial nucleation-promoting factor that mediates actin-based motility, and PlcB, a phospholipase that mediates vacuole escape. Here we investigated the role of the metalloprotease Mpl in the dissemination process. In agreement with previous findings showing that Mpl is required for PlcB activation, infection of epithelial cells with the ΔplcB or Δmpl strains resulted in the formation of small infection foci. As expected, the ΔplcB strain displayed a strong defect in vacuole escape. However, the Δmpl strain showed an unexpected defect in the resolution of protrusions into vacuoles, in addition to the expected but mild defect in vacuole escape. The Δmpl strain displayed increased levels of ActA on the bacterial surface in protrusions. We mapped an Mpl-dependent processing site in ActA between amino acid residues 207 to 238. Similar to the Δmpl strain, the ΔactA207-238 strain displayed increased levels of ActA on the bacterial surface in protrusions. Although the ΔactA207-238 strain displayed wild-type actin-based motility, it formed small infection foci and failed to resolve protrusions into vacuoles. We propose that, in addition to its role in PlcB processing and vacuole escape, the metalloprotease Mpl is required for ActA processing and protrusion resolution.
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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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21
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Lu R, Herrera BB, Eshleman HD, Fu Y, Bloom A, Li Z, Sacks DB, Goldberg MB. Shigella Effector OspB Activates mTORC1 in a Manner That Depends on IQGAP1 and Promotes Cell Proliferation. PLoS Pathog 2015; 11:e1005200. [PMID: 26473364 PMCID: PMC4608727 DOI: 10.1371/journal.ppat.1005200] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 09/10/2015] [Indexed: 12/12/2022] Open
Abstract
The intracellular bacterial pathogen Shigella infects and spreads through the human intestinal epithelium. Effector proteins delivered by Shigella into cells promote infection by modulating diverse host functions. We demonstrate that the effector protein OspB interacts directly with the scaffolding protein IQGAP1, and that the absence of either OspB or IQGAP1 during infection leads to larger areas of S. flexneri spread through cell monolayers. We show that the effect on the area of bacterial spread is due to OspB triggering increased cell proliferation at the periphery of infected foci, thereby replacing some of the cells that die within infected foci and restricting the area of bacterial spread. We demonstrate that OspB enhancement of cell proliferation results from activation of mTORC1, a master regulator of cell growth, and is blocked by the mTORC1-specific inhibitor rapamycin. OspB activation of mTORC1, and its effects on cell proliferation and bacterial spread, depends on IQGAP1. Our results identify OspB as a regulator of mTORC1 and mTORC1-dependent cell proliferation early during S. flexneri infection and establish a role for IQGAP1 in mTORC1 signaling. They also raise the possibility that IQGAP1 serves as a scaffold for the assembly of an OspB-mTORC1 signaling complex. During infection, Shigella spp. deliver into the cytoplasm of cells effector proteins that manipulate host cell processes in ways that promote infection and bacterial spread. We have discovered that the Shigella effector protein OspB interacts with the cellular scaffolding protein IQGAP1. OspB induces increased cell proliferation by activating mTORC1 kinase, a master regulator of cellular growth, in a manner that depends on IQGAP1. As IQGAP1 has been shown to interact with mTOR and with the mTORC1 activators ERK1/2, we propose that IQGAP1 serves as a scaffold for OspB activation of mTORC1. The presence of OspB and IQGAP1 lead to restricting the area of spread of S. flexneri in cell monolayers; our data support a model in which the effect of OspB and IQGAP1 on the area of S. flexneri spread is due to effects on cell proliferation locally within infected foci. As infection of cells and tissue by Shigella spp. leads to cell death, increased local cellular proliferation may serve to provide additional protective intracellular niches for the organism within infected tissue.
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Affiliation(s)
- Richard Lu
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, Massachusetts, United States of America
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Bobby Brooke Herrera
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, Massachusetts, United States of America
| | - Heather D. Eshleman
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, Massachusetts, United States of America
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yang Fu
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, Massachusetts, United States of America
| | - Alexander Bloom
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, Massachusetts, United States of America
| | - Zhigang Li
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
| | - David B. Sacks
- Department of Laboratory Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Marcia B. Goldberg
- Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, Massachusetts, United States of America
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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22
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Lee SY, Gertler FB, Goldberg MB. Vasodilator-stimulated phosphoprotein restricts cell-to-cell spread of Shigella flexneri at the cell periphery. MICROBIOLOGY-SGM 2015; 161:2149-60. [PMID: 26358985 DOI: 10.1099/mic.0.000173] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Shigella spp. are intracellular bacterial pathogens that cause diarrhoeal disease in humans. Shigella utilize the host actin cytoskeleton to enter cells, move through the cytoplasm of cells and pass into adjacent cells. Ena/VASP family proteins are highly conserved proteins that participate in actin-dependent dynamic cellular processes. We tested whether Ena/VASP family members VASP (vasodilator-stimulated phosphoprotein), Mena (mammalian-enabled) or EVL (Ena-VASP-like) contribute to Shigella flexneri spread through cell monolayers. VASP and EVL restricted cell-to-cell spread without significantly altering actin-based motility, whereas Mena had no effect on these processes. Phosphorylation of VASP on Ser153, Ser235 and Thr274 regulated its subcellular distribution and function. VASP derivatives that lack the Ena/VASP homology 1 (EVH1) domain or contain a phosphoablative mutation of Ser153 were defective in restricting S. flexneri spread, indicating that the EVH1 domain and phosphorylation on Ser153 are required for this process. The EVH1 domain and Ser153 of VASP were required for VASP localization to focal adhesions, and localization of VASP to focal adhesions and/or the leading edge was required for restriction of spread. The contribution of the EVH1 domain was from both the donor and the recipient cell, whereas the contribution of Ser153 phosphorylation was only from the donor cell. Thus, unlike host proteins characterized in Shigella pathogenesis that promote bacterial spread, VASP and EVL function to limit it. The ability of VASP and EVL to limit spread highlights the critical role of focal adhesion complexes and/or the leading edge in bacterial passage between cells.
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Affiliation(s)
- Soo Young Lee
- 1Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Frank B Gertler
- 2Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Marcia B Goldberg
- 1Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA 3Division of Infectious Diseases, Massachusetts General Hospital, Cambridge, MA 02139, USA
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23
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Tran ENH, Attridge SR, Teh MY, Morona R. Shigella flexneri cell-to-cell spread, and growth and inflammation in mice, is limited by the outer membrane protease IcsP. FEMS Microbiol Lett 2015; 362:fnv088. [PMID: 26025071 DOI: 10.1093/femsle/fnv088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2015] [Indexed: 12/20/2022] Open
Abstract
The Shigella flexneri autotransporter protein IcsA is essential for intra- and intercellular spread, and icsA mutants are attenuated in several models. However, the pathogenic significance of the outer membrane protease IcsP, which orchestrates the polar distribution of IcsA on the bacterial surface, remains unclear. To further examine this point, we constructed icsP mutants in the two most commonly studied S. flexneri strains and evaluated their in vitro and in vivo performance relative to wild type. Both icsP mutants showed aberrant surface distribution of IcsA, but the in vitro consequences depended upon the cell line being used to assess bacterial motility and plaque formation. Evaluating the behaviour of the mutants in two mouse models suggested functional expression of icsP might limit bacterial persistence and the associated inflammation in host tissues, consistent with the findings in one of the three cell lines used.
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Affiliation(s)
- Elizabeth Ngoc Hoa Tran
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Stephen R Attridge
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Min Yan Teh
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Renato Morona
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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24
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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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