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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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Miner MV, Rauch I. Why put yourself on a pedestal? The pathogenic role of the A/E pedestal. Infect Immun 2024:e0048923. [PMID: 38591884 DOI: 10.1128/iai.00489-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024] Open
Abstract
Certain Escherichia coli (E. coli) strains are attaching and effacing (A/E) lesion pathogens that primarily infect intestinal epithelial cells. They cause actin restructuring and polymerization within the host cell to create an actin-rich protrusion below the site of adherence, termed the pedestal. Although there is clarity on the pathways initiating pedestal formation, the underlying purpose(s) of the pedestal remains ambiguous. The conservation of pedestal-forming activity across multiple pathogens and redundancy in formation pathways indicate a pathogenic advantage. However, few decisive conclusions have been drawn, given that the results vary between model systems. Some research argues that the pedestal increases the colonization capability of the bacterium. These studies utilize A/E pathogens specifically deficient in pedestal formation to evaluate adhesion and intestinal colonization following infection. There have been many proposed mechanisms for the colonization benefit conferred by the pedestal. One suggested benefit is that the pedestal allows for direct cytosolic anchoring through incorporation of the established host cortical actin, causing a stable link between the pathogen and cell structure. The pedestal may confer enhanced motility, as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) are better able to migrate on the surface of host cells and infect neighboring cells in the presence of the pedestal. Additionally, some research suggests that the pedestal improves effector delivery. This review will investigate the purpose of pedestal formation using evidence from recent literature and will critically evaluate the methodology and model systems. Most importantly, we will contextualize the proposed functions to reconcile potential synergistic effects.
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Affiliation(s)
- M V Miner
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
| | - I Rauch
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
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3
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Li W, Yuan W, Huang S, Zou L, Zheng K, Xie D. Research progress on the mechanism of Treponema pallidum breaking through placental barrier. Microb Pathog 2023; 185:106392. [PMID: 37852552 DOI: 10.1016/j.micpath.2023.106392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/12/2023] [Accepted: 10/12/2023] [Indexed: 10/20/2023]
Abstract
Congenital syphilis, a significant cause of fetal mortality worldwide, is a congenital infectious disease instigated by the vertical transmission of Treponema pallidum during pregnancy. Clinical manifestations include preterm delivery, stillbirth, neonatal skin lesions, skeletal abnormalities, and central nervous system aberrations. The ongoing increase in the incidence of congenital syphilis, coupled with complexities in diagnosis, necessitates a detailed understanding of its pathogenesis for the development of improved diagnostic approaches, and to interrupt the route of vertical transmission. Drawing from the broader body of research associated with vertical transmission pathogens, we aim to clarify the potential mechanisms by which Treponema pallidum breaches the placental barrier to infect the fetus.
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Affiliation(s)
- Weiwei Li
- Department of Clinical Laboratory, The Second People's Hospital of Foshan, China
| | - Wei Yuan
- The Fourth Affiliated Hospital of Nanchang University, China
| | - Shaobin Huang
- Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, Institution of Pathogenic Biology, University of South China, Hengyang, China
| | - Lin Zou
- Department of Clinical Laboratory, The Second People's Hospital of Foshan, China
| | - Kang Zheng
- Department of Clinical Laboratory, Hengyang Central Hospital, Hengyang, China.
| | - Dongde Xie
- Department of Clinical Laboratory, The Second People's Hospital of Foshan, China.
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Cencer CS, Silverman JB, Meenderink LM, Krystofiak ES, Millis BA, Tyska MJ. Adhesion-based capture stabilizes nascent microvilli at epithelial cell junctions. Dev Cell 2023; 58:2048-2062.e7. [PMID: 37832537 PMCID: PMC10615885 DOI: 10.1016/j.devcel.2023.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 07/21/2023] [Accepted: 09/14/2023] [Indexed: 10/15/2023]
Abstract
To maximize solute transport, epithelial cells build an apical "brush border," where thousands of microvilli are linked to their neighbors by protocadherin-containing intermicrovillar adhesion complexes (IMACs). Previous studies established that the IMAC is needed to build a mature brush border, but how this complex contributes to the accumulation of new microvilli during differentiation remains unclear. We found that early in differentiation, mouse, human, and porcine epithelial cells exhibit a marginal accumulation of microvilli, which span junctions and interact with protrusions on neighboring cells using IMAC protocadherins. These transjunctional IMACs are highly stable and reinforced by tension across junctions. Finally, long-term live imaging showed that the accumulation of microvilli at cell margins consistently leads to accumulation in medial regions. Thus, nascent microvilli are stabilized by a marginal capture mechanism that depends on the formation of transjunctional IMACs. These results may offer insights into how apical specializations are assembled in diverse epithelial systems.
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Affiliation(s)
- Caroline S Cencer
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jennifer B Silverman
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Leslie M Meenderink
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University Medical Center, Nashville, TN 37232, USA; United States Department of Veterans Affairs, Tennessee Valley Health Care System, Nashville, TN 37212, USA
| | - Evan S Krystofiak
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Bryan A Millis
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biomedical Engineering, Vanderbilt University School of Engineering, Nashville, TN 37235, USA
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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5
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Cencer CS, Silverman JB, Meenderink LM, Krystofiak ES, Millis BA, Tyska MJ. Adhesion-based capture stabilizes nascent microvilli at epithelial cell junctions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.08.531705. [PMID: 36945471 PMCID: PMC10028856 DOI: 10.1101/2023.03.08.531705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Differentiated transporting epithelial cells present an extensive apical array of microvilli - a "brush border" - where neighboring microvilli are linked together by intermicrovillar adhesion complexes (IMACs) composed of protocadherins CDHR2 and CDHR5. Although loss-of-function studies provide strong evidence that IMAC function is needed to build a mature brush border, how the IMAC contributes to the stabilization and accumulation of nascent microvilli remains unclear. We found that, early in differentiation, the apical surface exhibits a marginal accumulation of microvilli, characterized by higher packing density relative to medial regions of the surface. While medial microvilli are highly dynamic and sample multiple orientations over time, marginal protrusions exhibit constrained motion and maintain a vertical orientation. Unexpectedly, we found that marginal microvilli span the junctional space and contact protrusions on neighboring cells, mediated by complexes of CDHR2/CDHR5. FRAP analysis indicated that these transjunctional IMACs are highly stable relative to adhesion complexes between medial microvilli, which explains the restricted motion of protrusions in the marginal zone. Finally, long-term live imaging revealed that the accumulation of microvilli at cell margins consistently leads to accumulation in medial regions of the cell. Collectively, our findings suggest that nascent microvilli are stabilized by a capture mechanism that is localized to cell margins and enabled by the transjunctional formation of IMACs. These results inform our understanding of how apical specializations are assembled in diverse epithelial systems.
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Escherichia coli 0157:H7 virulence factors and the ruminant reservoir. Curr Opin Infect Dis 2022; 35:205-214. [PMID: 35665714 PMCID: PMC9302714 DOI: 10.1097/qco.0000000000000834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review updates recent findings about Escherichia coli O157:H7 virulence factors and its bovine reservoir. This Shiga toxin (Stx)-producing E. coli belongs to the Enterohemorrhagic E. coli (EHEC) pathotype causing hemorrhagic colitis. Its low infectious dose makes it an efficient, severe, foodborne pathogen. Although EHEC remains in the intestine, Stx can translocate systemically and is cytotoxic to microvascular endothelial cells, especially in the kidney and brain. Disease can progress to life-threatening hemolytic uremic syndrome (HUS) with hemolytic anemia, acute kidney failure, and thrombocytopenia. Young children, the immunocompromised, and the elderly are at the highest risk for HUS. Healthy ruminants are the major reservoir of EHEC and cattle are the primary source of human exposure. RECENT FINDINGS Advances in understanding E. coli O157:H7 pathogenesis include molecular mechanisms of virulence, bacterial adherence, type three secretion effectors, intestinal microbiome, inflammation, and reservoir maintenance. SUMMARY Many aspects of E. coli O157:H7 disease remain unclear and include the role of the human and bovine intestinal microbiomes in infection. Therapeutic strategies involve controlling inflammatory responses and/or intestinal barrier function. Finally, elimination/reduction of E. coli O157:H7 in cattle using CRISPR-engineered conjugative bacterial plasmids and/or on-farm management likely hold solutions to reduce infections and increase food safety/security.
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7
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Park AJ, Wright MA, Roach EJ, Khursigara CM. Imaging host-pathogen interactions using epithelial and bacterial cell infection models. J Cell Sci 2021; 134:134/5/jcs250647. [PMID: 33622798 DOI: 10.1242/jcs.250647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The age-old saying, seeing is believing, could not be truer when we think about the value of imaging interactions between epithelial cells and bacterial pathogens. Imaging and culturing techniques have vastly improved over the years, and the breadth and depth of these methods is ever increasing. These technical advances have benefited researchers greatly; however, due to the large number of potential model systems and microscopy techniques to choose from, it can be overwhelming to select the most appropriate tools for your research question. This Review discusses a variety of available epithelial culturing methods and quality control experiments that can be performed, and outlines various options commonly used to fluorescently label bacterial and mammalian cell components. Both light- and electron-microscopy techniques are reviewed, with descriptions of both technical aspects and common applications. Several examples of imaging bacterial pathogens and their interactions with epithelial cells are discussed to provide researchers with an idea of the types of biological questions that can be successfully answered by using microscopy.
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Affiliation(s)
- Amber J Park
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Madison A Wright
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Elyse J Roach
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.,Molecular and Cellular Imaging Facility, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Cezar M Khursigara
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada .,Molecular and Cellular Imaging Facility, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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8
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Romão FT, Martins FH, Hernandes RT, Ooka T, Santos FF, Yamamoto D, Bonfim-Melo A, Jones N, Hayashi T, Elias WP, Sperandio V, Gomes TAT. Genomic Properties and Temporal Analysis of the Interaction of an Invasive Escherichia albertii With Epithelial Cells. Front Cell Infect Microbiol 2020; 10:571088. [PMID: 33392102 PMCID: PMC7772469 DOI: 10.3389/fcimb.2020.571088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 11/03/2020] [Indexed: 12/17/2022] Open
Abstract
Diarrhea is one of the main causes of infant mortality worldwide, mainly in the developing world. Among the various etiologic agents, Escherichia albertii is emerging as an important human enteropathogen. E. albertii promote attaching and effacing (AE) lesions due to the presence of the locus of enterocyte effacement (LEE) that encodes a type three secretion system (T3SS), the afimbrial adhesin intimin and its translocated receptor, Tir, and several effector proteins. We previously showed that E. albertii strain 1551-2 invades several epithelial cell lineages by a process that is dependent on the intimin-Tir interaction. To understand the contribution of T3SS-dependent effectors present in E. albertii 1551-2 during the invasion process, we performed a genetic analysis of the LEE and non-LEE genes and evaluated the expression of the LEE operons in various stages of bacterial interaction with differentiated intestinal Caco-2 cells. The kinetics of the ability of the 1551-2 strain to colonize and form AE lesions was also investigated in epithelial HeLa cells. We showed that the LEE expression was constant during the early stages of infection but increased at least 4-fold during bacterial persistence in the intracellular compartment. An in silico analysis indicated the presence of a new tccP/espFU subtype, named tccP3. We found that the encoded protein colocalizes with Tir and polymerized F-actin during the infection process in vitro. Moreover, assays performed with Nck null cells demonstrated that the 1551-2 strain can trigger F-actin polymerization in an Nck-independent pathway, despite the fact that TccP3 is not required for this phenotype. Our study highlights the importance of the T3SS during the invasion process and for the maintenance of E. albertii 1551-2 inside the cells. In addition, this work may help to elucidate the versatility of the T3SS for AE pathogens, which are usually considered extracellular and rarely reach the intracellular environment.
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Affiliation(s)
- Fabiano T Romão
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM-UNIFESP), São Paulo, Brazil.,Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Fernando H Martins
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Laboratório de Bacteriologia, Instituto Butantan, São Paulo, Brazil
| | - Rodrigo T Hernandes
- Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, Brazil
| | - Tadasuke Ooka
- Department of Microbiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
| | - Fernanda F Santos
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM-UNIFESP), São Paulo, Brazil
| | - Denise Yamamoto
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM-UNIFESP), São Paulo, Brazil.,Universidade Santo Amaro, São Paulo, Brazil
| | - Alexis Bonfim-Melo
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM-UNIFESP), São Paulo, Brazil
| | - Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Tetsuya Hayashi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Waldir P Elias
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, Brazil
| | - Vanessa Sperandio
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, United States.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Tânia A T Gomes
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM-UNIFESP), São Paulo, Brazil
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9
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EPEC Recruits a Cdc42-Specific GEF, Frabin, To Facilitate PAK Activation and Host Cell Colonization. mBio 2020; 11:mBio.01423-20. [PMID: 33144373 PMCID: PMC7642674 DOI: 10.1128/mbio.01423-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) is a leading cause of diarrhea in children, especially in the developing world. EPEC initiates infection by attaching to cells in the host intestine, triggering the formation of actin-rich “pedestal” structures directly beneath the adherent pathogen. These bacteria inject their own receptor into host cells, which upon binding to a protein on the pathogen surface triggers pedestal formation. Multiple other proteins are also delivered into the cells of the host intestine, which work together to hijack host signaling pathways to drive pedestal production. Here we show how EPEC hijacks a host protein, Frabin, which creates the conditions in the cell necessary for the pathogen to manipulate a specific pathway that promotes pedestal formation. This provides new insights into this essential early stage in disease caused by EPEC. Enteropathogenic Escherichia coli (EPEC) is an extracellular pathogen that tightly adheres to host cells by forming “actin pedestals” beneath the bacteria, a critical step in pathogenesis. EPEC injects effector proteins that manipulate host cell signaling cascades to trigger pedestal assembly. We have recently shown that one such effector, EspG, hijacks p21-activated kinase (PAK) and sustains its activated state to drive the cytoskeletal changes necessary for attachment of the pathogen to target cells. This EspG subversion of PAK required active Rho family small GTPases in the host cell. Here we show that EPEC itself promotes the activation of Rho GTPases by recruiting Frabin, a host guanine nucleotide exchange factor (GEF) for the Rho GTPase Cdc42. Cells devoid of Frabin showed significantly lower EPEC-induced PAK activation, pedestal formation, and bacterial attachment. Frabin recruitment to sites of EPEC attachment was driven by EspG and required localized enrichment of phosphatidylinositol 4,5-bisphosphate (PIP2) and host Arf6. Our findings identify Frabin as a key target for EPEC to ensure the activation status of cellular GTPases required for actin pedestal formation.
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Dhanda AS, Yang D, Kooner A, Guttman JA. Distribution of PDLIM1 at actin-rich structures generated by invasive and adherent bacterial pathogens. Anat Rec (Hoboken) 2020; 304:919-938. [PMID: 33022122 DOI: 10.1002/ar.24523] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/06/2020] [Accepted: 07/28/2020] [Indexed: 12/15/2022]
Abstract
The enteric bacterial pathogens Listeria monocytogenes (Listeria) and enteropathogenic Escherichia coli (EPEC) remodel the eukaryotic actin cytoskeleton during their disease processes. Listeria generate slender actin-rich comet/rocket tails to move intracellularly, and later, finger-like membrane protrusions to spread amongst host cells. EPEC remain extracellular, but generate similar actin-rich membranous protrusions (termed pedestals) to move atop the host epithelia. These structures are crucial for disease as diarrheal (and systemic) infections are significantly abrogated during infections with mutant strains that are unable to generate the structures. The current repertoire of host components enriched within these structures is vast and diverse. In this protein catalog, we and others have found that host actin crosslinkers, such as palladin and α-actinin-1, are routinely exploited. To expand on this list, we set out to investigate the distribution of PDLIM1, a scaffolding protein and binding partner of palladin and α-actinin-1, during bacterial infections. We show that PDLIM1 localizes to the site of initial Listeria entry into cells. Following this, PDLIM1 localizes to actin filament clouds surrounding immotile bacteria, and then colocalizes with actin once the comet/rocket tails are generated. Unlike palladin or α-actinin-1, PDLIM1 is maintained within the actin-rich core of membrane protrusions. Conversely, α-actinin-1, but not PDLIM1 (or palladin), is enriched at the membrane invagination that internalizes the Listeria-containing membrane protrusion. We also show that PDLIM1 is a component of the EPEC pedestal core and that its recruitment is dependent on the bacterial effector Tir. Our findings highlight PDLIM1 as another protein present within pathogen-induced actin-rich structures.
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Affiliation(s)
- Aaron S Dhanda
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Diana Yang
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Avneen Kooner
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Julian A Guttman
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
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11
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Dhanda AS, Yang D, Guttman JA. Localization of alpha-actinin-4 during infections by actin remodeling bacteria. Anat Rec (Hoboken) 2020; 304:1400-1419. [PMID: 33099893 DOI: 10.1002/ar.24548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/13/2020] [Accepted: 09/12/2020] [Indexed: 11/12/2022]
Abstract
Bacterial pathogens cause disease by subverting the structure and function of their target host cells. Several foodborne agents such as Listeria monocytogenes (L. monocytogenes), Shigella flexneri (S. flexneri), Salmonella enterica serovar Typhimurium (S. Typhimurium) and enteropathogenic Escherichia coli (EPEC) manipulate the host actin cytoskeleton to cause diarrheal (and systemic) infections. During infections, these invasive and adherent pathogens hijack the actin filaments of their host cells and rearrange them into discrete actin-rich structures that promote bacterial adhesion (via pedestals), invasion (via membrane ruffles and endocytic cups), intracellular motility (via comet/rocket tails) and/or intercellular dissemination (via membrane protrusions and invaginations). We have previously shown that actin-rich structures generated by L. monocytogenes contain the host actin cross-linker α-actinin-4. Here we set out to examine α-actinin-4 during other key steps of the L. monocytogenes infectious cycle as well as characterize the subcellular distribution of α-actinin-4 during infections with other model actin-hijacking bacterial pathogens (S. flexneri, S. Typhimurium and EPEC). Although α-actinin-4 is absent at sites of initial L. monocytogenes invasion, we show that it is a new component of the membrane invaginations formed during secondary infections of neighboring host cells. Importantly, we reveal that α-actinin-4 also localizes to the major actin-rich structures generated during cell culture infections with S. flexneri (comet/rocket tails and membrane protrusions), S. Typhimurium (membrane ruffles) and EPEC (pedestals). Taken together, these findings suggest that α-actinin-4 is a host factor that is exploited by an assortment of actin-hijacking bacterial pathogens.
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Affiliation(s)
- Aaron S Dhanda
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Diana Yang
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Julian A Guttman
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
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12
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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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13
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Whelan R, McVicker G, Leo JC. Staying out or Going in? The Interplay between Type 3 and Type 5 Secretion Systems in Adhesion and Invasion of Enterobacterial Pathogens. Int J Mol Sci 2020; 21:E4102. [PMID: 32521829 PMCID: PMC7312957 DOI: 10.3390/ijms21114102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/12/2022] Open
Abstract
Enteric pathogens rely on a variety of toxins, adhesins and other virulence factors to cause infections. Some of the best studied pathogens belong to the Enterobacterales order; these include enteropathogenic and enterohemorrhagic Escherichia coli, Shigella spp., and the enteropathogenic Yersiniae. The pathogenesis of these organisms involves two different secretion systems, a type 3 secretion system (T3SS) and type 5 secretion systems (T5SSs). The T3SS forms a syringe-like structure spanning both bacterial membranes and the host cell plasma membrane that translocates toxic effector proteins into the cytoplasm of the host cell. T5SSs are also known as autotransporters, and they export part of their own polypeptide to the bacterial cell surface where it exerts its function, such as adhesion to host cell receptors. During infection with these enteropathogens, the T3SS and T5SS act in concert to bring about rearrangements of the host cell cytoskeleton, either to invade the cell, confer intracellular motility, evade phagocytosis or produce novel structures to shelter the bacteria. Thus, in these bacteria, not only the T3SS effectors but also T5SS proteins could be considered "cytoskeletoxins" that bring about profound alterations in host cell cytoskeletal dynamics and lead to pathogenic outcomes.
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Affiliation(s)
| | | | - Jack C. Leo
- Antimicrobial Resistance, Omics and Microbiota Group, Department of Biosciences, Nottingham Trent University, Nottingham NG1 4FQ, UK; (R.W.); (G.M.)
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EspFu-Mediated Actin Assembly Enhances Enteropathogenic Escherichia coli Adherence and Activates Host Cell Inflammatory Signaling Pathways. mBio 2020; 11:mBio.00617-20. [PMID: 32291304 PMCID: PMC7157822 DOI: 10.1128/mbio.00617-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
EPEC is among the leading causes of diarrheal disease worldwide. The colonization of the gut mucosa by EPEC results in actin pedestal formation at the site of bacterial attachment. These pedestals are referred to as attaching and effacing (AE) lesions. Here, we exploit the different molecular mechanisms used by EPEC to induce AE lesions on epithelial cells, showing that the effector EspFu is associated with increased bacterial attachment and enhanced epithelial colonization compared to the Tir-Nck pathway. Moreover, we also showed that actin pedestal formation can counterbalance the anti-inflammatory activity induced by EPEC, especially when driven by EspFu. Collectively, our findings provide new insights into virulence mechanisms employed by EPEC to colonize epithelial cells, as well as the host response to this enteric pathogen. The translocation of effectors into the host cell through type 3 secretion systems (T3SS) is a sophisticated strategy employed by pathogenic bacteria to subvert host responses and facilitate colonization. Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) utilize the Tir and EspFu (also known as TccP) effectors to remodel the host cytoskeleton, culminating in the formation of attaching and effacing (AE) lesions on enterocytes. While some EPEC strains require tyrosine phosphorylation of Tir and recruitment of the host Nck to trigger actin polymerization, EHEC and certain EPEC strains, whose Tir is not phosphorylated, rely on the effector EspFu for efficient actin remodeling. Here, we investigated the role played by Tir-Nck and Tir-EspFu actin polymerization pathways during the infection of epithelial cells, as well as the host transcriptional response to the AE lesion formation induced by EPEC. We found that EspFu-mediated actin assembly promotes bacterial attachment and epithelial colonization more efficiently than Tir-Nck. Moreover, we showed that both actin polymerization mechanisms can activate inflammatory pathways and reverse the anti-inflammatory response induced by EPEC in epithelial cells. However, this activity is remarkably more evident in infections with EspFu-expressing EPEC strains. This study demonstrates the complex interactions between effector-mediated actin remodeling and inflammation. Different strains carry different combinations of these two effectors, highlighting the plasticity of pathogenic E. coli enteric infections.
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Chánez-Paredes S, Montoya-García A, Schnoor M. Cellular and pathophysiological consequences of Arp2/3 complex inhibition: role of inhibitory proteins and pharmacological compounds. Cell Mol Life Sci 2019; 76:3349-3361. [PMID: 31073744 PMCID: PMC11105272 DOI: 10.1007/s00018-019-03128-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 04/30/2019] [Accepted: 05/02/2019] [Indexed: 02/06/2023]
Abstract
The actin-related protein complex 2/3 (Arp2/3) generates branched actin networks important for many cellular processes such as motility, vesicular trafficking, cytokinesis, and intercellular junction formation and stabilization. Activation of Arp2/3 requires interaction with actin nucleation-promoting factors (NPFs). Regulation of Arp2/3 activity is achieved by endogenous inhibitory proteins through direct binding to Arp2/3 and competition with NPFs or by binding to Arp2/3-induced actin filaments and disassembly of branched actin networks. Arp2/3 inhibition has recently garnered more attention as it has been associated with attenuation of cancer progression, neurotoxic effects during drug abuse, and pathogen invasion of host cells. In this review, we summarize current knowledge on expression, inhibitory mechanisms and function of endogenous proteins able to inhibit Arp2/3 such as coronins, GMFs, PICK1, gadkin, and arpin. Moreover, we discuss cellular consequences of pharmacological Arp2/3 inhibition.
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Affiliation(s)
- Sandra Chánez-Paredes
- Department for Molecular Biomedicine, CINVESTAV-IPN, Av. IPN 2508, San Pedro Zacatenco, GAM, 07360, Mexico City, Mexico
| | - Armando Montoya-García
- Department for Molecular Biomedicine, CINVESTAV-IPN, Av. IPN 2508, San Pedro Zacatenco, GAM, 07360, Mexico City, Mexico
| | - Michael Schnoor
- Department for Molecular Biomedicine, CINVESTAV-IPN, Av. IPN 2508, San Pedro Zacatenco, GAM, 07360, Mexico City, Mexico.
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Dhanda AS, Yu C, Guttman JA. Distribution of CD147 During Enteropathogenic Escherichia coli and Salmonella enterica Serovar Typhimurium Infections. Anat Rec (Hoboken) 2019; 302:2224-2232. [PMID: 31443124 DOI: 10.1002/ar.24235] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 05/02/2019] [Accepted: 05/16/2019] [Indexed: 12/22/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) and Salmonella enterica serovar Typhimurium (S. Typhimurium) are highly infectious gastrointestinal human pathogens. These microbes inject bacterial-derived effector proteins directly into the host cell cytosol as part of their disease processes. A common host subcellular target of these pathogens is the actin cytoskeleton, which is commandeered by the bacteria and is used during their attachment onto (EPEC) or invasion into (S. Typhimurium) the host cells. We previously demonstrated that the host enzyme cyclophilin A (CypA) is recruited to the actin-rich regions of EPEC pedestals and S. Typhimurium membrane ruffles. To further expand the growing catalogue of host proteins usurped by actin-hijacking bacteria, we examined the host plasma membrane protein and cognate receptor of CypA, CD147, during EPEC and S. Typhimurium infections. Here, we show that CD147 is enriched at the basolateral regions of pedestals but, unlike CypA, it is absent from their actin-rich core. We show that the CD147 recruitment to these areas requires EPEC pedestal formation and not solely bacteria-host cell contact. Additionally, we demonstrate that the depletion of CD147 by siRNA does not alter the formation of pedestals. Finally, we show that CD147 is also a component of actin-rich membrane ruffles generated during S. Typhimurium invasion of host cells. Collectively, our findings establish CD147 as another host component present at dynamic actin-rich structures formed during bacterial infections. Anat Rec, 302:2224-2232, 2019. © 2019 American Association for Anatomy.
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Affiliation(s)
- Aaron S Dhanda
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Connie Yu
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Julian A Guttman
- Department of Biological Sciences, Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
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Velle KB, Campellone KG. Enteropathogenic E. coli relies on collaboration between the formin mDia1 and the Arp2/3 complex for actin pedestal biogenesis and maintenance. PLoS Pathog 2018; 14:e1007485. [PMID: 30550556 PMCID: PMC6310289 DOI: 10.1371/journal.ppat.1007485] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 12/28/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022] Open
Abstract
Enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC) are closely related extracellular pathogens that reorganize host cell actin into “pedestals” beneath the tightly adherent bacteria. This pedestal-forming activity is both a critical step in pathogenesis, and it makes EPEC and EHEC useful models for studying the actin rearrangements that underlie membrane protrusions. To generate pedestals, EPEC relies on the tyrosine phosphorylated bacterial effector protein Tir to bind host adaptor proteins that recruit N-WASP, a nucleation-promoting factor that activates the Arp2/3 complex to drive actin polymerization. In contrast, EHEC depends on the effector EspFU to multimerize N-WASP and promote Arp2/3 activation. Although these core pathways of pedestal assembly are well-characterized, the contributions of additional actin nucleation factors are unknown. We investigated potential cooperation between the Arp2/3 complex and other classes of nucleators using chemical inhibitors, siRNAs, and knockout cell lines. We found that inhibition of formins impairs actin pedestal assembly, motility, and cellular colonization for bacteria using the EPEC, but not the EHEC, pathway of actin polymerization. We also identified mDia1 as the formin contributing to EPEC pedestal assembly, as its expression level positively correlates with the efficiency of pedestal formation, and it localizes to the base of pedestals both during their initiation and once they have reached steady state. Collectively, our data suggest that mDia1 enhances EPEC pedestal biogenesis and maintenance by generating seed filaments to be used by the N-WASP-Arp2/3-dependent actin nucleation machinery and by sustaining Src-mediated phosphorylation of Tir. Microbial pathogens that rearrange the host actin cytoskeleton have made valuable contributions to our understanding of cell signaling and movement. The assembly and organization of the actin cytoskeleton is driven by proteins called nucleators, which can be manipulated by bacteria including enteropathogenic Escherichia coli (EPEC), a frequent cause of pediatric diarrhea in developing countries. After ingestion, EPEC adhere tightly to cells of the intestine and hijack the underlying cytoskeleton to create protrusions called actin pedestals. While mechanisms of pedestal assembly involving a nucleator called the Arp2/3 complex have been defined for EPEC, the contribution of additional host nucleators has not been determined. We assessed the roles of several actin nucleators in EPEC pedestals and found that in addition to Arp2/3 complex-mediated nucleation, the formin mDia1 is a key contributor to actin assembly. These findings highlight the importance of nucleator collaboration in pathogenesis, and also advance our understanding of the molecular and cellular basis of EPEC infection, which is ultimately important for the discovery of new drug targets.
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Affiliation(s)
- Katrina B. Velle
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
| | - Kenneth G. Campellone
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
- * E-mail:
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Login FH, Jensen HH, Pedersen GA, Amieva MR, Nejsum LN. The soluble extracellular domain of E-cadherin interferes with EPEC adherence via interaction with the Tir:intimin complex. FASEB J 2018; 32:fj201800651. [PMID: 29920220 DOI: 10.1096/fj.201800651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Enteropathogenic Escherichia coli (EPEC) causes watery diarrhea when colonizing the surface of enterocytes. The translocated intimin receptor (Tir):intimin receptor complex facilitates tight adherence to epithelial cells and formation of actin pedestals beneath EPEC. We found that the host cell adherens junction protein E-cadherin (Ecad) was recruited to EPEC microcolonies. Live-cell and confocal imaging revealed that Ecad recruitment depends on, and occurs after, formation of the Tir:intimin complex. Combinatorial binding experiments using wild-type EPEC, isogenic mutants lacking Tir or intimin, and E. coli expressing intimin showed that the extracellular domain of Ecad binds the bacterial surface in a Tir:intimin-dependent manner. Finally, addition of the soluble extracellular domain of Ecad to the infection medium or depletion of Ecad extracellular domain from the cell surface reduced EPEC adhesion to host cells. Thus, the soluble extracellular domain of Ecad may be used in the design of intervention strategies targeting EPEC adherence to host cells.-Login, F. H., Jensen, H. H., Pedersen, G. A., Amieva, M. R., Nejsum, L. N. The soluble extracellular domain of E-cadherin interferes with EPEC adherence via interaction with the Tir:intimin complex.
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Affiliation(s)
- Frédéric H Login
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Helene H Jensen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Gitte A Pedersen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Manuel R Amieva
- Department of Pediatrics, Stanford University, Stanford, California, USA
- Department of Microbiology and Immunology, Stanford University, Stanford, California, USA
| | - Lene N Nejsum
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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