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Patel D, Hansen M, Lambert C, Hegde S, Jayamohan H, Gale BK, Sant HJ. Characterizing a Silver Nanoparticle-Based Electrochemical Biosensor for Shiga Toxin Detection. ACS OMEGA 2023; 8:40898-40903. [PMID: 37929116 PMCID: PMC10620918 DOI: 10.1021/acsomega.3c06083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 09/28/2023] [Indexed: 11/07/2023]
Abstract
Shiga toxins (1, 2) regularly cause outbreaks and food recalls and pose a significant health risk to the infected population. Therefore, new reliable tools are needed to rapidly detect Shiga toxin cost-effectively in food, water, and wastewater before human consumption. Enzyme immunoassay and polymerase chain reaction approaches are the gold standard detection methods for the Shiga toxin. However, these methods require expensive instruments along with expensive reagents, which makes them hard to convert into point-of-use and low-cost systems. This study introduces an electrochemical biosensing method that utilizes silver nanoparticles (AgNPs) as electrochemical tags and commercially available low-cost screen-printed carbon electrodes for detection. This study introduces the modification of reference electrodes on commercially available screen-printed carbon electrodes to detect AgNPs dissolved in nitric acid. This biosensor achieved a 2 ng/mL lowest measured concentration for Shiga toxin-1 in less than 3 h. These biosensor results also showed that the AgNP-based sensor has better linearity (for graph between peak current vs concentration) and lower standard deviation compared to gold nanoparticles (AuNP)-based electrochemical biosensors.
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Affiliation(s)
- Dhruv Patel
- Department
of Mechanical Engineering, University of
Utah, Salt Lake
City, Utah 84112, United States
| | - Madison Hansen
- Department
of Biology, University of Utah, Salt Lake City, Utah 84112, United States
| | - Christopher Lambert
- Department
of Mechanical Engineering, University of
Utah, Salt Lake
City, Utah 84112, United States
- Espira
Inc., 825 N 300 W Suite
N-223, Salt Lake City, Utah 84103, United States
| | - Shruti Hegde
- Department
of Chemical Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Harikrishnan Jayamohan
- Department
of Mechanical Engineering, University of
Utah, Salt Lake
City, Utah 84112, United States
| | - Bruce K. Gale
- Department
of Mechanical Engineering, University of
Utah, Salt Lake
City, Utah 84112, United States
- Espira
Inc., 825 N 300 W Suite
N-223, Salt Lake City, Utah 84103, United States
| | - Himanshu Jayant Sant
- Department
of Mechanical Engineering, University of
Utah, Salt Lake
City, Utah 84112, United States
- Department
of Chemical Engineering, University of Utah, Salt Lake City, Utah 84112, United States
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2
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Targeting the Inside of Cells with Biologicals: Toxin Routes in a Therapeutic Context. BioDrugs 2023; 37:181-203. [PMID: 36729328 PMCID: PMC9893211 DOI: 10.1007/s40259-023-00580-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2023] [Indexed: 02/03/2023]
Abstract
Numerous toxins translocate to the cytosol in order to fulfil their function. This demonstrates the existence of routes for proteins from the extracellular space to the cytosol. Understanding these routes is relevant to multiple aspects related to therapeutic applications. These include the development of anti-toxin treatments, the potential use of toxins as shuttles for delivering macromolecular cargo to the cytosol or the use of drugs based on toxins. Compared with other strategies for delivery, such as chemicals as carriers for macromolecular delivery or physical methods like electroporation, toxin routes present paths into the cell that potentially cause less damage and can be specifically targeted. The efficiency of delivery via toxin routes is limited. However, low-delivery efficiencies can be entirely sufficient, if delivered cargoes possess an amplification effect or if very few molecules are sufficient for inducing the desired effects. This is known for example from RNA-based vaccines that have been developed during the coronavirus disease 2019 pandemic as well as for other approved RNA-based drugs, which elicited the desired effect despite their typically low delivery efficiencies. The different mechanisms by which toxins enter cells may have implications for their technological utility. We review the mechanistic principles of the translocation pathway of toxins from the extracellular space to the cytosol, the delivery efficiencies, and therapeutic strategies or applications that exploit toxin routes for intracellular delivery.
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3
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Chaurasia R, Vinetz JM. In silico prediction of molecular mechanisms of toxicity mediated by the leptospiral PF07598 gene family-encoded virulence-modifying proteins. Front Mol Biosci 2023; 9:1092197. [PMID: 36756251 PMCID: PMC9900628 DOI: 10.3389/fmolb.2022.1092197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/20/2022] [Indexed: 01/24/2023] Open
Abstract
Mechanisms of leptospirosis pathogenesis remain unclear despite the identification of a number of potential leptospiral virulence factors. We recently demonstrated potential mechanisms by which the virulence-modifying (VM) proteins-defined as containing a Domain of Unknown function (DUF1561), encoded by the PF07598 gene family-found only in group 1 pathogenic Leptospira-might mediate the clinical pathogenesis of leptospirosis. VM proteins belongs to classical AB toxin paradigm though have a unique AB domain architecture, unlike other AB toxins such as diphtheria toxin, pertussis toxin, shiga toxin, or ricin toxin which are typically encoded by two or more genes and self-assembled into a multi-domain holotoxin. Leptospiral VM proteins are secreted R-type lectin domain-containing exotoxins with discrete N-terminal ricin B-like domains involved in host cell surface binding, and a C-terminal DNase/toxin domain. Here we use the artificial intelligence-based AlphaFold algorithm and other computational tools to predict and elaborate on details of the VM protein structure-function relationship. Comparative AlphaFold and CD-spectroscopy defined the consistent secondary structure (Helix and ß-sheet) content, and the stability of the functional domains were further supported by molecular dynamics simulation. VM proteins comprises distinctive lectic family (QxW)3 motifs, the Mycoplasma CARDS toxin (D3 domain, aromatic patches), C-terminal similarity with mammalian DNase I. In-silico study proposed that Gln412, Gln523, His533, Thr59 are the high binding energy or ligand binding residues plausibly anticipates in the functional activities. Divalent cation (Mg+2-Gln412) and phosphate ion (PO4]-3-Arg615) interaction further supports the functional activities driven by C-terminal domain. Computation-driven structure-function studies of VM proteins will guide experimentation towards mechanistic understandings of leptospirosis pathogenesis, which underlie development of new therapeutic and preventive measures for this devastating disease.
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4
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Hotinger JA, Morris ST, May AE. The Case against Antibiotics and for Anti-Virulence Therapeutics. Microorganisms 2021; 9:2049. [PMID: 34683370 PMCID: PMC8537500 DOI: 10.3390/microorganisms9102049] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 12/14/2022] Open
Abstract
Although antibiotics have been indispensable in the advancement of modern medicine, there are downsides to their use. Growing resistance to broad-spectrum antibiotics is leading to an epidemic of infections untreatable by first-line therapies. Resistance is exacerbated by antibiotics used as growth factors in livestock, over-prescribing by doctors, and poor treatment adherence by patients. This generates populations of resistant bacteria that can then spread resistance genes horizontally to other bacterial species, including commensals. Furthermore, even when antibiotics are used appropriately, they harm commensal bacteria leading to increased secondary infection risk. Effective antibiotic treatment can induce bacterial survival tactics, such as toxin release and increasing resistance gene transfer. These problems highlight the need for new approaches to treating bacterial infection. Current solutions include combination therapies, narrow-spectrum therapeutics, and antibiotic stewardship programs. These mediate the issues but do not address their root cause. One emerging solution to these problems is anti-virulence treatment: preventing bacterial pathogenesis instead of using bactericidal agents. In this review, we discuss select examples of potential anti-virulence targets and strategies that could be developed into bacterial infection treatments: the bacterial type III secretion system, quorum sensing, and liposomes.
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Affiliation(s)
| | | | - Aaron E. May
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23219, USA; (J.A.H.); (S.T.M.)
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5
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Robb Huhn G, Torres-Mangual N, Clore J, Cilenti L, Frisan T, Teter K. Endocytosis of the CdtA subunit from the Haemophilus ducreyi cytolethal distending toxin. Cell Microbiol 2021; 23:e13380. [PMID: 34292647 DOI: 10.1111/cmi.13380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 12/30/2022]
Abstract
Many Gram-negative pathogens produce a cytolethal distending toxin (CDT) with two cell-binding subunits (CdtA + CdtC) and a catalytic CdtB subunit. After adhesion to the plasma membrane of a target cell, CDT moves by retrograde transport to endoplasmic reticulum. CdtB then enters the nucleus where it generates DNA breaks that lead to cell cycle arrest and apoptosis or senescence. CdtA anchors the CDT holotoxin to the plasma membrane and is thought to remain on the cell surface after endocytosis of the CdtB/CdtC heterodimer. Here, we re-examined the potential endocytosis and intracellular transport of CdtA from the Haemophilus ducreyi CDT. We recorded the endocytosis of holotoxin-associated CdtA with a cell-based enzyme-linked immunoabsorbent assay (CELISA) and visualised its presence in the early endosomes by confocal microscopy 10 min after CDT binding to the cell surface. Western blot analysis documented the rapid degradation of internalised CdtA. Most of internalised CdtB and CdtC were degraded as well. The rapid rate of CDT internalisation and turnover, which could explain why CdtA endocytosis was not detected in previous studies, suggests only a minor pool of cell-associated CdtB reaches the nucleus. Our work demonstrates that CDT is internalised as an intact holotoxin and identifies the endosomes as the site of CdtA dissociation from CdtB/CdtC. TAKE AWAYS: During the endocytosis of CDT, CdtA is thought to remain at the cell surface. A cell-based ELISA documented the rapid endocytosis of CdtA. CdtA was visualised in the early endosomes by confocal microscopy. Intracellular CdtA was rapidly degraded, along with most of CdtB and CdtC.
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Affiliation(s)
- G Robb Huhn
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Naly Torres-Mangual
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA.,Colorado State University, Fort Collins, CO, USA
| | - John Clore
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Lucia Cilenti
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Teresa Frisan
- Department of Molecular Biology, Umeå University, Umeå, Sweden.,Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Ken Teter
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
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6
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Lingwood C. Therapeutic Uses of Bacterial Subunit Toxins. Toxins (Basel) 2021; 13:toxins13060378. [PMID: 34073185 PMCID: PMC8226680 DOI: 10.3390/toxins13060378] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 02/07/2023] Open
Abstract
The B subunit pentamer verotoxin (VT aka Shiga toxin-Stx) binding to its cellular glycosphingolipid (GSL) receptor, globotriaosyl ceramide (Gb3) mediates internalization and the subsequent receptor mediated retrograde intracellular traffic of the AB5 subunit holotoxin to the endoplasmic reticulum. Subunit separation and cytosolic A subunit transit via the ER retrotranslocon as a misfolded protein mimic, then inhibits protein synthesis to kill cells, which can cause hemolytic uremic syndrome clinically. This represents one of the most studied systems of prokaryotic hijacking of eukaryotic biology. Similarly, the interaction of cholera AB5 toxin with its GSL receptor, GM1 ganglioside, is the key component of the gastrointestinal pathogenesis of cholera and follows the same retrograde transport pathway for A subunit cytosol access. Although both VT and CT are the cause of major pathology worldwide, the toxin–receptor interaction is itself being manipulated to generate new approaches to control, rather than cause, disease. This arena comprises two areas: anti neoplasia, and protein misfolding diseases. CT/CTB subunit immunomodulatory function and anti-cancer toxin immunoconjugates will not be considered here. In the verotoxin case, it is clear that Gb3 (and VT targeting) is upregulated in many human cancers and that there is a relationship between GSL expression and cancer drug resistance. While both verotoxin and cholera toxin similarly hijack the intracellular ERAD quality control system of nascent protein folding, the more widespread cell expression of GM1 makes cholera the toxin of choice as the means to more widely utilise ERAD targeting to ameliorate genetic diseases of protein misfolding. Gb3 is primarily expressed in human renal tissue. Glomerular endothelial cells are the primary VT target but Gb3 is expressed in other endothelial beds, notably brain endothelial cells which can mediate the encephalopathy primarily associated with VT2-producing E. coli infection. The Gb3 levels can be regulated by cytokines released during EHEC infection, which complicate pathogenesis. Significantly Gb3 is upregulated in the neovasculature of many tumours, irrespective of tumour Gb3 status. Gb3 is markedly increased in pancreatic, ovarian, breast, testicular, renal, astrocytic, gastric, colorectal, cervical, sarcoma and meningeal cancer relative to the normal tissue. VT has been shown to be effective in mouse xenograft models of renal, astrocytoma, ovarian, colorectal, meningioma, and breast cancer. These studies are herein reviewed. Both CT and VT (and several other bacterial toxins) access the cell cytosol via cell surface ->ER transport. Once in the ER they interface with the protein folding homeostatic quality control pathway of the cell -ERAD, (ER associated degradation), which ensures that only correctly folded nascent proteins are allowed to progress to their cellular destinations. Misfolded proteins are translocated through the ER membrane and degraded by cytosolic proteosome. VT and CT A subunits have a C terminal misfolded protein mimic sequence to hijack this transporter to enter the cytosol. This interface between exogenous toxin and genetically encoded endogenous mutant misfolded proteins, provides a new therapeutic basis for the treatment of such genetic diseases, e.g., Cystic fibrosis, Gaucher disease, Krabbe disease, Fabry disease, Tay-Sachs disease and many more. Studies showing the efficacy of this approach in animal models of such diseases are presented.
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Affiliation(s)
- Clifford Lingwood
- Division of Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada;
- Departments of Laboratory Medicine & Pathobiology, and Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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7
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Lingwood C. Verotoxin Receptor-Based Pathology and Therapies. Front Cell Infect Microbiol 2020; 10:123. [PMID: 32296648 PMCID: PMC7136409 DOI: 10.3389/fcimb.2020.00123] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/05/2020] [Indexed: 12/22/2022] Open
Abstract
Verotoxin, VT (aka Shiga toxin,Stx) is produced by enterohemorrhagic E. coli (EHEC) and is the key pathogenic factor in EHEC-induced hemolytic uremic syndrome (eHUS-hemolytic anemia/thrombocytopenia/glomerular infarct) which can follow gastrointestinal EHEC infection, particularly in children. This AB5 subunit toxin family bind target cell globotriaosyl ceramide (Gb3), a glycosphingolipid (GSL) (aka CD77, pk blood group antigen) of the globoseries of neutral GSLs, initiating lipid raft-dependent plasma membrane Gb3 clustering, membrane curvature, invagination, scission, endosomal trafficking, and retrograde traffic via the TGN to the Golgi, and ER. In the ER, A/B subunits separate and the A subunit hijacks the ER reverse translocon (dislocon-used to eliminate misfolded proteins-ER associated degradation-ERAD) for cytosolic access. This property has been used to devise toxoid-based therapy to temporarily block ERAD and rescue the mutant phenotype of several genetic protein misfolding diseases. The A subunit avoids cytosolic proteosomal degradation, to block protein synthesis via its RNA glycanase activity. In humans, Gb3 is primarily expressed in the kidney, particularly in the glomerular endothelial cells. Here, Gb3 is in lipid rafts (more ordered membrane domains which accumulate GSLs/cholesterol) whereas renal tubular Gb3 is in the non-raft membrane fraction, explaining the basic pathology of eHUS (glomerular endothelial infarct). Females are more susceptible and this correlates with higher renal Gb3 expression. HUS can be associated with encephalopathy, more commonly following verotoxin 2 exposure. Gb3 is expressed in the microvasculature of the brain. All members of the VT family bind Gb3, but with varying affinity. VT2e (pig edema toxin) binds Gb4 preferentially. Verotoxin-specific therapeutics based on chemical analogs of Gb3, though effective in vitro, have failed in vivo. While some analogs are effective in animal models, there are no good rodent models of eHUS since Gb3 is not expressed in rodent glomeruli. However, the mouse mimics the neurological symptoms more closely and provides an excellent tool to assess therapeutics. In addition to direct cytotoxicity, other factors including VT–induced cytokine release and aberrant complement cascade, are now appreciated as important in eHUS. Based on atypical HUS therapy, treatment of eHUS patients with anticomplement antibodies has proven effective in some cases. A recent switch using stem cells to try to reverse, rather than prevent VT induced pathology may prove a more effective methodology.
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Affiliation(s)
- Clifford Lingwood
- Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
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8
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RAB5A and TRAPPC6B are novel targets for Shiga toxin 2a inactivation in kidney epithelial cells. Sci Rep 2020; 10:4945. [PMID: 32188865 PMCID: PMC7080763 DOI: 10.1038/s41598-020-59694-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 01/30/2020] [Indexed: 12/21/2022] Open
Abstract
The cardinal virulence factor of human-pathogenic enterohaemorrhagic Escherichia coli (EHEC) is Shiga toxin (Stx), which causes severe extraintestinal complications including kidney failure by damaging renal endothelial cells. In EHEC pathogenesis, the disturbance of the kidney epithelium by Stx becomes increasingly recognised, but how this exactly occurs is unknown. To explore this molecularly, we investigated the Stx receptor content and transcriptomic profile of two human renal epithelial cell lines: highly Stx-sensitive ACHN cells and largely Stx-insensitive Caki-2 cells. Though both lines exhibited the Stx receptor globotriaosylceramide, RNAseq revealed strikingly different transcriptomic responses to an Stx challenge. Using RNAi to silence factors involved in ACHN cells’ Stx response, the greatest protection occurred when silencing RAB5A and TRAPPC6B, two host factors that we newly link to Stx trafficking. Silencing these factors alongside YKT6 fully prevented the cytotoxic Stx effect. Overall, our approach reveals novel subcellular targets for potential therapies against Stx-mediated kidney failure.
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9
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Balasubramanian S, Pandranki L, Maupin S, Ramasamy K, Taylor AB, Hart PJ, Baseman JB, Kannan TR. Disulfide bond of Mycoplasma pneumoniae community-acquired respiratory distress syndrome toxin is essential to maintain the ADP-ribosylating and vacuolating activities. Cell Microbiol 2019; 21:e13032. [PMID: 30977272 DOI: 10.1111/cmi.13032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/19/2019] [Accepted: 04/03/2019] [Indexed: 01/13/2023]
Abstract
Mycoplasma pneumoniae is the leading cause of bacterial community-acquired pneumonia among hospitalised children in United States and worldwide. Community-acquired respiratory distress syndrome (CARDS) toxin is a key virulence determinant of M. pneumoniae. The N-terminus of CARDS toxin exhibits ADP-ribosyltransferase (ADPRT) activity, and the C-terminus possesses binding and vacuolating activities. Thiol-trapping experiments of wild-type (WT) and cysteine-to-serine-mutated CARDS toxins with alkylating agents identified disulfide bond formation at the amino terminal cysteine residues C230 and C247. Compared with WT and other mutant toxins, C247S was unstable and unusable for comparative studies. Although there were no significant variations in binding, entry, and retrograde trafficking patterns of WT and mutated toxins, C230S did not elicit vacuole formation in intoxicated cells. In addition, the ADPRT domain of C230S was more sensitive to all tested proteases when compared with WT toxin. Despite its in vitro ADPRT activity, the reduction of C230S CARDS toxin-mediated ADPRT activity-associated IL-1β production in U937 cells and the recovery of vacuolating activity in the protease-released carboxy region of C230S indicated that the disulfide bond was essential not only to maintain the conformational stability of CARDS toxin but also to properly execute its cytopathic effects.
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Affiliation(s)
- Sowmya Balasubramanian
- Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Lavanya Pandranki
- Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Suzanna Maupin
- Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Kumaraguruparan Ramasamy
- Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Alexander B Taylor
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX.,X-ray Crystallography Core Laboratory, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Peter John Hart
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX.,X-ray Crystallography Core Laboratory, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Joel B Baseman
- Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Thirumalai R Kannan
- Department of Microbiology, Immunology and Molecular Genetics, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
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10
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Nowakowska-Gołacka J, Sominka H, Sowa-Rogozińska N, Słomińska-Wojewódzka M. Toxins Utilize the Endoplasmic Reticulum-Associated Protein Degradation Pathway in Their Intoxication Process. Int J Mol Sci 2019; 20:E1307. [PMID: 30875878 PMCID: PMC6471375 DOI: 10.3390/ijms20061307] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 03/08/2019] [Accepted: 03/10/2019] [Indexed: 12/25/2022] Open
Abstract
Several bacterial and plant AB-toxins are delivered by retrograde vesicular transport to the endoplasmic reticulum (ER), where the enzymatically active A subunit is disassembled from the holotoxin and transported to the cytosol. In this process, toxins subvert the ER-associated degradation (ERAD) pathway. ERAD is an important part of cellular regulatory mechanism that targets misfolded proteins to the ER channels, prior to their retrotranslocation to the cytosol, ubiquitination and subsequent degradation by a protein-degrading complex, the proteasome. In this article, we present an overview of current understanding of the ERAD-dependent transport of AB-toxins to the cytosol. We describe important components of ERAD and discuss their significance for toxin transport. Toxin recognition and disassembly in the ER, transport through ER translocons and finally cytosolic events that instead of overall proteasomal degradation provide proper folding and cytotoxic activity of AB-toxins are discussed as well. We also comment on recent reports presenting medical applications for toxin transport through the ER channels.
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Affiliation(s)
- Jowita Nowakowska-Gołacka
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
| | - Hanna Sominka
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
| | - Natalia Sowa-Rogozińska
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
| | - Monika Słomińska-Wojewódzka
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland.
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11
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Kieckens E, Rybarczyk J, Cox E, Vanrompay D. Antibacterial and immunomodulatory activities of bovine lactoferrin against Escherichia coli O157:H7 infections in cattle. Biometals 2018; 31:321-330. [PMID: 29442205 DOI: 10.1007/s10534-018-0082-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 02/06/2018] [Indexed: 12/27/2022]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a zoonotic pathogen that causes food-borne disease in humans ranging from watery diarrhea to bloody diarrhea and severe hemorrhagic colitis, renal failure and hemolytic uremic syndrome. Cattle, the most important source of E. coli O157:H7 transmission to humans, harbor the bacteria in their gastrointestinal tract without showing clinical symptoms. Prevention of E. coli O157:H7 infections in ruminants could diminish the public health risk. However, there is no specific treatment available nor a vaccine or a therapeutic agent which completely prevents E. coli O157:H7 infections in cattle. This paper provides an overview of latest research data on eradicating enterohemorrhagic E. coli O157:H7 in ruminants by use of bovine lactoferrin administration. The article provides insights into the anti-microbial and immunomodulatory activities of bovine lactoferrin against E. coli O157:H7 infections in cattle.
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Affiliation(s)
- Evelien Kieckens
- Laboratory of Immunology and Animal Biotechnology, Department of Animal Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Joanna Rybarczyk
- Laboratory of Immunology and Animal Biotechnology, Department of Animal Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Eric Cox
- Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium
| | - Daisy Vanrompay
- Laboratory of Immunology and Animal Biotechnology, Department of Animal Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
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12
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Cellular recovery from exposure to sub-optimal concentrations of AB toxins that inhibit protein synthesis. Sci Rep 2018; 8:2494. [PMID: 29410492 PMCID: PMC5802730 DOI: 10.1038/s41598-018-20861-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 01/25/2018] [Indexed: 01/31/2023] Open
Abstract
Ricin, Shiga toxin, exotoxin A, and diphtheria toxin are AB-type protein toxins that act within the host cytosol and kill the host cell through pathways involving the inhibition of protein synthesis. It is thought that a single molecule of cytosolic toxin is sufficient to kill the host cell. Intoxication is therefore viewed as an irreversible process. Using flow cytometry and a fluorescent reporter system to monitor protein synthesis, we show a single molecule of cytosolic toxin is not sufficient for complete inhibition of protein synthesis or cell death. Furthermore, cells can recover from intoxication: cells with a partial loss of protein synthesis will, upon removal of the toxin, increase the level of protein production and survive the toxin challenge. Thus, in contrast to the prevailing model, ongoing toxin delivery to the cytosol appears to be required for the death of cells exposed to sub-optimal toxin concentrations.
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13
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Kavaliauskiene S, Dyve Lingelem AB, Skotland T, Sandvig K. Protection against Shiga Toxins. Toxins (Basel) 2017; 9:E44. [PMID: 28165371 PMCID: PMC5331424 DOI: 10.3390/toxins9020044] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 01/18/2017] [Accepted: 01/19/2017] [Indexed: 12/12/2022] Open
Abstract
Shiga toxins consist of an A-moiety and five B-moieties able to bind the neutral glycosphingolipid globotriaosylceramide (Gb3) on the cell surface. To intoxicate cells efficiently, the toxin A-moiety has to be cleaved by furin and transported retrogradely to the Golgi apparatus and to the endoplasmic reticulum. The enzymatically active part of the A-moiety is then translocated to the cytosol, where it inhibits protein synthesis and in some cell types induces apoptosis. Protection of cells can be provided either by inhibiting binding of the toxin to cells or by interfering with any of the subsequent steps required for its toxic effect. In this article we provide a brief overview of the interaction of Shiga toxins with cells, describe some compounds and conditions found to protect cells against Shiga toxins, and discuss whether they might also provide protection in animals and humans.
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Affiliation(s)
- Simona Kavaliauskiene
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, N-0379 Oslo, Norway.
- Center for Cancer Biomedicine, Faculty of Medicine, Oslo University Hospital, N-0379 Oslo, Norway.
| | - Anne Berit Dyve Lingelem
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, N-0379 Oslo, Norway.
- Center for Cancer Biomedicine, Faculty of Medicine, Oslo University Hospital, N-0379 Oslo, Norway.
| | - Tore Skotland
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, N-0379 Oslo, Norway.
- Center for Cancer Biomedicine, Faculty of Medicine, Oslo University Hospital, N-0379 Oslo, Norway.
| | - Kirsten Sandvig
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, N-0379 Oslo, Norway.
- Center for Cancer Biomedicine, Faculty of Medicine, Oslo University Hospital, N-0379 Oslo, Norway.
- Department of Biosciences, University of Oslo, N-0316 Oslo, Norway.
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14
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Bielaszewska M, Rüter C, Bauwens A, Greune L, Jarosch KA, Steil D, Zhang W, He X, Lloubes R, Fruth A, Kim KS, Schmidt MA, Dobrindt U, Mellmann A, Karch H. Host cell interactions of outer membrane vesicle-associated virulence factors of enterohemorrhagic Escherichia coli O157: Intracellular delivery, trafficking and mechanisms of cell injury. PLoS Pathog 2017; 13:e1006159. [PMID: 28158302 PMCID: PMC5310930 DOI: 10.1371/journal.ppat.1006159] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 02/15/2017] [Accepted: 12/30/2016] [Indexed: 01/15/2023] Open
Abstract
Outer membrane vesicles (OMVs) are important tools in bacterial virulence but their role in the pathogenesis of infections caused by enterohemorrhagic Escherichia coli (EHEC) O157, the leading cause of life-threatening hemolytic uremic syndrome, is poorly understood. Using proteomics, electron and confocal laser scanning microscopy, immunoblotting, and bioassays, we investigated OMVs secreted by EHEC O157 clinical isolates for virulence factors cargoes, interactions with pathogenetically relevant human cells, and mechanisms of cell injury. We demonstrate that O157 OMVs carry a cocktail of key virulence factors of EHEC O157 including Shiga toxin 2a (Stx2a), cytolethal distending toxin V (CdtV), EHEC hemolysin, and flagellin. The toxins are internalized by cells via dynamin-dependent endocytosis of OMVs and differentially separate from vesicles during intracellular trafficking. Stx2a and CdtV-B, the DNase-like CdtV subunit, separate from OMVs in early endosomes. Stx2a is trafficked, in association with its receptor globotriaosylceramide within detergent-resistant membranes, to the Golgi complex and the endoplasmic reticulum from where the catalytic Stx2a A1 fragment is translocated to the cytosol. CdtV-B is, after its retrograde transport to the endoplasmic reticulum, translocated to the nucleus to reach DNA. CdtV-A and CdtV-C subunits remain OMV-associated and are sorted with OMVs to lysosomes. EHEC hemolysin separates from OMVs in lysosomes and targets mitochondria. The OMV-delivered CdtV-B causes cellular DNA damage, which activates DNA damage responses leading to G2 cell cycle arrest. The arrested cells ultimately die of apoptosis induced by Stx2a and CdtV via caspase-9 activation. By demonstrating that naturally secreted EHEC O157 OMVs carry and deliver into cells a cocktail of biologically active virulence factors, thereby causing cell death, and by performing first comprehensive analysis of intracellular trafficking of OMVs and OMV-delivered virulence factors, we provide new insights into the pathogenesis of EHEC O157 infections. Our data have implications for considering O157 OMVs as vaccine candidates. Enterohemorrhagic Escherichia coli (EHEC) O157, the leading EHEC group causing diarrhea and the life-threatening hemolytic uremic syndrome in humans, produce several virulence factors which play distinct roles in the pathogenesis of these diseases. However, the mechanisms of their secretion and host cell injury are poorly understood. We show here that EHEC O157 strains isolated from patients shed nanostructures termed outer membrane vesicles (OMVs) which contain major EHEC O157 virulence factors including Shiga toxin 2a (Stx2a), cytolethal distending toxin V (CdtV), EHEC hemolysin, and flagellin. The OMVs are taken up by human intestinal epithelial and renal and brain microvascular endothelial cells, which are the major targets during EHEC O157 infections, and deliver the virulence factors intracellularly. Inside cells the virulence factors separate from OMVs and are transported via different pathways to their target compartments including the cytosol (Stx2a), nucleus (CdtV-B subunit), and mitochondria (EHEC hemolysin). Cells exposed to EHEC O157 OMVs develop G2 cell cycle arrest induced by CdtV-B-mediated DNA damage. This is followed by apoptotic cell death triggered by Stx2a and CdtV via caspase-9 activation. OMVs thus serve as novel tools of EHEC O157-mediated host injury and are quite likely involved in the pathogenesis of human diseases.
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Affiliation(s)
| | - Christian Rüter
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Andreas Bauwens
- Institute of Hygiene, University of Münster, Münster, Germany
| | - Lilo Greune
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | | | - Daniel Steil
- Institute of Hygiene, University of Münster, Münster, Germany
| | - Wenlan Zhang
- Institute of Hygiene, University of Münster, Münster, Germany
| | - Xiaohua He
- Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture (USDA), Albany, California, United States of America
| | - Roland Lloubes
- Laboratoire d'Ingenierie des Systemes Macromoleculaires UMR7255, CNRS-Aix-Marseille Université, Marseille, France
| | - Angelika Fruth
- National Reference Center for Salmonella and Other Enteric Pathogens, Robert Koch Institute, Branch Wernigerode, Wernigerode, Germany
| | - Kwang Sik Kim
- Division of Pediatric Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - M. Alexander Schmidt
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Ulrich Dobrindt
- Institute of Hygiene, University of Münster, Münster, Germany
| | - Alexander Mellmann
- Institute of Hygiene, University of Münster, Münster, Germany
- Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Münster, Germany
| | - Helge Karch
- Institute of Hygiene, University of Münster, Münster, Germany
- Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Münster, Germany
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15
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Shiga Toxins as Multi-Functional Proteins: Induction of Host Cellular Stress Responses, Role in Pathogenesis and Therapeutic Applications. Toxins (Basel) 2016; 8:toxins8030077. [PMID: 26999205 PMCID: PMC4810222 DOI: 10.3390/toxins8030077] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 02/25/2016] [Accepted: 02/29/2016] [Indexed: 12/17/2022] Open
Abstract
Shiga toxins (Stxs) produced by Shiga toxin-producing bacteria Shigella dysenteriae serotype 1 and select serotypes of Escherichia coli are primary virulence factors in the pathogenesis of hemorrhagic colitis progressing to potentially fatal systemic complications, such as hemolytic uremic syndrome and central nervous system abnormalities. Current therapeutic options to treat patients infected with toxin-producing bacteria are limited. The structures of Stxs, toxin-receptor binding, intracellular transport and the mode of action of the toxins have been well defined. However, in the last decade, numerous studies have demonstrated that in addition to being potent protein synthesis inhibitors, Stxs are also multifunctional proteins capable of activating multiple cell stress signaling pathways, which may result in apoptosis, autophagy or activation of the innate immune response. Here, we briefly present the current understanding of Stx-activated signaling pathways and provide a concise review of therapeutic applications to target tumors by engineering the toxins.
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16
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Pathogenic Mechanisms of Actin Cross-Linking Toxins: Peeling Away the Layers. Curr Top Microbiol Immunol 2016; 399:87-112. [PMID: 27858184 DOI: 10.1007/82_2016_22] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Actin cross-linking toxins are produced by Gram-negative bacteria from Vibrio and Aeromonas genera. The toxins were named actin cross-linking domains (ACD), since the first and most of the subsequently discovered ACDs were found as effector domains in larger MARTX and VgrG toxins. Among recognized human pathogens, ACD is produced by Vibrio cholerae, Vibrio vulnificus, and Aeromonas hydrophila. Upon delivery to the cytoplasm of a host cell, ACD covalently cross-links actin monomers into non-polymerizable actin oligomers of various lengths. Provided sufficient doses of toxin are delivered, most or all actin can be promptly cross-linked into non-functional oligomers, leading to cell rounding, detachment from the substrate and, in many cases, cell death. Recently, a deeper layer of ACD toxicity with a less obvious but more potent mechanism was discovered. According to this finding, low doses of the ACD-produced actin oligomers can actively disrupt the actin cytoskeleton by potently inhibiting essential actin assembly proteins, formins. The first layer of toxicity is direct (as actin is the immediate and the only target), passive (since ACD-cross-linked actin oligomers are toxic only because they are non-functional), and less potent (as bulk quantities of one of the most abundant cytoplasmic proteins, actin, have to be modified). The second mechanism is indirect (as major targets, formins, are not affected by ACD directly), active (because actin oligomers act as "secondary" toxins), and highly potent [as it affects scarce and essential actin-binding proteins (ABPs)].
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17
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Oxidative Stress in Shiga Toxin Production by Enterohemorrhagic Escherichia coli. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:3578368. [PMID: 26798420 PMCID: PMC4699097 DOI: 10.1155/2016/3578368] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/30/2015] [Indexed: 12/28/2022]
Abstract
Virulence of enterohemorrhagic Escherichia coli (EHEC) strains depends on production of Shiga toxins. These toxins are encoded in genomes of lambdoid bacteriophages (Shiga toxin-converting phages), present in EHEC cells as prophages. The genes coding for Shiga toxins are silent in lysogenic bacteria, and prophage induction is necessary for their efficient expression and toxin production. Under laboratory conditions, treatment with UV light or antibiotics interfering with DNA replication are commonly used to induce lambdoid prophages. Since such conditions are unlikely to occur in human intestine, various research groups searched for other factors or agents that might induce Shiga toxin-converting prophages. Among other conditions, it was reported that treatment with H2O2 caused induction of these prophages, though with efficiency significantly lower relative to UV-irradiation or mitomycin C treatment. A molecular mechanism of this phenomenon has been proposed. It appears that the oxidative stress represents natural conditions provoking induction of Shiga toxin-converting prophages as a consequence of H2O2 excretion by either neutrophils in infected humans or protist predators outside human body. Finally, the recently proposed biological role of Shiga toxin production is described in this paper, and the “bacterial altruism” and “Trojan Horse” hypotheses, which are connected to the oxidative stress, are discussed.
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18
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Shiga Toxins Activate the NLRP3 Inflammasome Pathway To Promote Both Production of the Proinflammatory Cytokine Interleukin-1β and Apoptotic Cell Death. Infect Immun 2015; 84:172-86. [PMID: 26502906 DOI: 10.1128/iai.01095-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023] Open
Abstract
Shiga toxin (Stx)-mediated immune responses, including the production of the proinflammatory cytokines tumor necrosis-α (TNF-α) and interleukin-1β (IL-1β), may exacerbate vascular damage and accelerate lethality. However, the immune signaling pathway activated in response to Stx is not well understood. Here, we demonstrate that enzymatically active Stx, which leads to ribotoxic stress, triggers NLRP3 inflammasome-dependent caspase-1 activation and IL-1β secretion in differentiated macrophage-like THP-1 (D-THP-1) cells. The treatment of cells with a chemical inhibitor of glycosphingolipid biosynthesis, which suppresses the expression of the Stx receptor globotriaosylceramide and subsequent endocytosis of the toxin, substantially blocked activation of the NLRP3 inflammasome and processing of caspase-1 and IL-1β. Processing and release of both caspase-1 and IL-1β were significantly reduced or abolished in Stx-intoxicated D-THP-1 cells in which the expression of NLRP3 or ASC was stably knocked down. Furthermore, Stx mediated the activation of caspases involved in apoptosis in an NLRP3- or ASC-dependent manner. In Stx-intoxicated cells, the NLRP3 inflammasome triggered the activation of caspase-8/3, leading to the initiation of apoptosis, in addition to caspase-1-dependent pyroptotic cell death. Taken together, these results suggest that Stxs trigger the NLRP3 inflammasome pathway to release proinflammatory IL-1β as well as to promote apoptotic cell death.
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Heisler DB, Kudryashova E, Grinevich DO, Suarez C, Winkelman JD, Birukov KG, Kotha SR, Parinandi NL, Vavylonis D, Kovar DR, Kudryashov DS. ACTIN-DIRECTED TOXIN. ACD toxin-produced actin oligomers poison formin-controlled actin polymerization. Science 2015; 349:535-9. [PMID: 26228148 DOI: 10.1126/science.aab4090] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The actin cross-linking domain (ACD) is an actin-specific toxin produced by several pathogens, including life-threatening spp. of Vibrio cholerae, Vibrio vulnificus, and Aeromonas hydrophila. Actin cross-linking by ACD is thought to lead to slow cytoskeleton failure owing to a gradual sequestration of actin in the form of nonfunctional oligomers. Here, we found that ACD converted cytoplasmic actin into highly toxic oligomers that potently "poisoned" the ability of major actin assembly proteins, formins, to sustain actin polymerization. Thus, ACD can target the most abundant cellular protein by using actin oligomers as secondary toxins to efficiently subvert cellular functions of actin while functioning at very low doses.
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Affiliation(s)
- David B Heisler
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA. The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA
| | - Elena Kudryashova
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA.
| | - Dmitry O Grinevich
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Cristian Suarez
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Jonathan D Winkelman
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Konstantin G Birukov
- Section of Pulmonary and Critical Care and Lung Injury Center, Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
| | - Sainath R Kotha
- Lipid Signaling and Lipidomics Laboratory, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Narasimham L Parinandi
- Lipid Signaling and Lipidomics Laboratory, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | | | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA. Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Dmitri S Kudryashov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA. The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA.
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20
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Garcia-Castillo MD, Tran T, Bobard A, Renard HF, Rathjen SJ, Dransart E, Stechmann B, Lamaze C, Lord M, Cintrat JC, Enninga J, Tartour E, Johannes L. Retrograde transport is not required for cytosolic translocation of the B-subunit of Shiga toxin. J Cell Sci 2015; 128:2373-87. [PMID: 25977475 DOI: 10.1242/jcs.169383] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 05/07/2015] [Indexed: 01/13/2023] Open
Abstract
Antigen-presenting cells have the remarkable capacity to transfer exogenous antigens to the cytosol for processing by proteasomes and subsequent presentation on major histocompatibility complex class-I (MHC-I) molecules, a process termed cross-presentation. This is the target of biomedical approaches that aim to trigger a therapeutic immune response. The receptor-binding B-subunit of Shiga toxin (STxB) has been developed as an antigen delivery tool for such immunotherapy applications. In this study, we have analyzed pathways and trafficking factors that are involved in this process. A covalent conjugate between STxB and saporin was generated to quantitatively sample the membrane translocation step to the cytosol in differentiated monocyte-derived THP-1 cells. We have found that retrograde trafficking to the Golgi complex was not required for STxB-saporin translocation to the cytosol or for STxB-dependent antigen cross-presentation. Depletion of endosomal Rab7 inhibited, and lowering membrane cholesterol levels favored STxB-saporin translocation. Interestingly, experiments with reducible and non-reducible linker-arm-STxB conjugates led to the conclusion that after translocation, STxB remains associated with the cytosolic membrane leaflet. In summary, we report new facets of the endosomal escape process bearing relevance to antigen cross-presentation.
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Affiliation(s)
- Maria Daniela Garcia-Castillo
- Institut Curie, PSL Research University, Endocytic Trafficking and Therapeutic Delivery Group, 26 rue d'Ulm, Paris Cedex 05 75248, France CNRS UMR3666, Paris 75005, France INSERM U1143, Paris 75005, France
| | - Thi Tran
- INSERM U970, PARCC Université Paris Descartes Sorbonne Paris Cité, Paris 75006, France Hôpital Européen Georges-Pompidou, AP-HP, Service d'Immunologie Biologique, Paris Cedex 15 75908, France
| | - Alexandre Bobard
- Dynamique des Interactions Hôte Pathogène, Institut Pasteur, Paris Cedex 15 75724, France
| | - Henri-François Renard
- Institut Curie, PSL Research University, Endocytic Trafficking and Therapeutic Delivery Group, 26 rue d'Ulm, Paris Cedex 05 75248, France CNRS UMR3666, Paris 75005, France INSERM U1143, Paris 75005, France
| | - Stefan J Rathjen
- Institut Curie, PSL Research University, Endocytic Trafficking and Therapeutic Delivery Group, 26 rue d'Ulm, Paris Cedex 05 75248, France CNRS UMR3666, Paris 75005, France INSERM U1143, Paris 75005, France
| | - Estelle Dransart
- Institut Curie, PSL Research University, Endocytic Trafficking and Therapeutic Delivery Group, 26 rue d'Ulm, Paris Cedex 05 75248, France CNRS UMR3666, Paris 75005, France INSERM U1143, Paris 75005, France
| | - Bahne Stechmann
- Institut Curie, PSL Research University, Endocytic Trafficking and Therapeutic Delivery Group, 26 rue d'Ulm, Paris Cedex 05 75248, France CNRS UMR3666, Paris 75005, France INSERM U1143, Paris 75005, France
| | - Christophe Lamaze
- CNRS UMR3666, Paris 75005, France INSERM U1143, Paris 75005, France Institut Curie - Centre de Recherche, Membrane Dynamics and Mechanics of Intracellular Signaling Group, 26 rue d'Ulm, Paris Cedex 05 75248, France
| | - Mike Lord
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | - Jost Enninga
- Dynamique des Interactions Hôte Pathogène, Institut Pasteur, Paris Cedex 15 75724, France
| | - Eric Tartour
- INSERM U970, PARCC Université Paris Descartes Sorbonne Paris Cité, Paris 75006, France Hôpital Européen Georges-Pompidou, AP-HP, Service d'Immunologie Biologique, Paris Cedex 15 75908, France
| | - Ludger Johannes
- Institut Curie, PSL Research University, Endocytic Trafficking and Therapeutic Delivery Group, 26 rue d'Ulm, Paris Cedex 05 75248, France CNRS UMR3666, Paris 75005, France INSERM U1143, Paris 75005, France
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Abstract
Shiga toxin (Stx) is one of the most potent bacterial toxins known. Stx is found in Shigella dysenteriae 1 and in some serogroups of Escherichia coli (called Stx1 in E. coli). In addition to or instead of Stx1, some E. coli strains produce a second type of Stx, Stx2, that has the same mode of action as Stx/Stx1 but is antigenically distinct. Because subtypes of each toxin have been identified, the prototype toxin for each group is now designated Stx1a or Stx2a. The Stxs consist of two major subunits, an A subunit that joins noncovalently to a pentamer of five identical B subunits. The A subunit of the toxin injures the eukaryotic ribosome and halts protein synthesis in target cells. The function of the B pentamer is to bind to the cellular receptor, globotriaosylceramide, Gb3, found primarily on endothelial cells. The Stxs traffic in a retrograde manner within the cell, such that the A subunit of the toxin reaches the cytosol only after the toxin moves from the endosome to the Golgi and then to the endoplasmic reticulum. In humans infected with Stx-producing E. coli, the most serious manifestation of the disease, hemolytic-uremic syndrome, is more often associated with strains that produce Stx2a rather than Stx1a, and that relative toxicity is replicated in mice and baboons. Stx1a and Stx2a also exhibit differences in cytotoxicity to various cell types, bind dissimilarly to receptor analogs or mimics, induce differential chemokine responses, and have several distinctive structural characteristics.
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Affiliation(s)
- Angela R. Melton-Celsa
- Department of Microbiology & Immunology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814,
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22
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Teter K. Toxin instability and its role in toxin translocation from the endoplasmic reticulum to the cytosol. Biomolecules 2013; 3:997-1029. [PMID: 24970201 PMCID: PMC4030972 DOI: 10.3390/biom3040997] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 11/26/2013] [Accepted: 11/27/2013] [Indexed: 12/21/2022] Open
Abstract
AB toxins enter a host cell by receptor-mediated endocytosis. The catalytic A chain then crosses the endosome or endoplasmic reticulum (ER) membrane to reach its cytosolic target. Dissociation of the A chain from the cell-binding B chain occurs before or during translocation to the cytosol, and only the A chain enters the cytosol. In some cases, AB subunit dissociation is facilitated by the unique physiology and function of the ER. The A chains of these ER-translocating toxins are stable within the architecture of the AB holotoxin, but toxin disassembly results in spontaneous or assisted unfolding of the isolated A chain. This unfolding event places the A chain in a translocation-competent conformation that promotes its export to the cytosol through the quality control mechanism of ER-associated degradation. A lack of lysine residues for ubiquitin conjugation protects the exported A chain from degradation by the ubiquitin-proteasome system, and an interaction with host factors allows the cytosolic toxin to regain a folded, active state. The intrinsic instability of the toxin A chain thus influences multiple steps of the intoxication process. This review will focus on the host-toxin interactions involved with A chain unfolding in the ER and A chain refolding in the cytosol.
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Affiliation(s)
- Ken Teter
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, 12722 Research Parkway, Orlando, FL 32826, USA.
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23
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Abstract
Ribosome-inactivating proteins (RIPs) were first isolated over a century ago and have been shown to be catalytic toxins that irreversibly inactivate protein synthesis. Elucidation of atomic structures and molecular mechanism has revealed these proteins to be a diverse group subdivided into two classes. RIPs have been shown to exhibit RNA N-glycosidase activity and depurinate the 28S rRNA of the eukaryotic 60S ribosomal subunit. In this review, we compare archetypal RIP family members with other potent toxins that abolish protein synthesis: the fungal ribotoxins which directly cleave the 28S rRNA and the newly discovered Burkholderia lethal factor 1 (BLF1). BLF1 presents additional challenges to the current classification system since, like the ribotoxins, it does not possess RNA N-glycosidase activity but does irreversibly inactivate ribosomes. We further discuss whether the RIP classification should be broadened to include toxins achieving irreversible ribosome inactivation with similar turnovers to RIPs, but through different enzymatic mechanisms.
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Affiliation(s)
- Matthew J Walsh
- RNA Biology Laboratory; Sheffield Institute for Translational Neuroscience (SITraN); Department of Neuroscience; University of Sheffield; Sheffield, UK
| | - Jennifer E Dodd
- RNA Biology Laboratory; Sheffield Institute for Translational Neuroscience (SITraN); Department of Neuroscience; University of Sheffield; Sheffield, UK
| | - Guillaume M Hautbergue
- RNA Biology Laboratory; Sheffield Institute for Translational Neuroscience (SITraN); Department of Neuroscience; University of Sheffield; Sheffield, UK
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24
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Identification of a peptide-based neutralizer that potently inhibits both Shiga toxins 1 and 2 by targeting specific receptor-binding regions. Infect Immun 2013; 81:2133-8. [PMID: 23545297 DOI: 10.1128/iai.01256-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shiga toxin (Stx) is a major virulence factor of enterohemorrhagic Escherichia coli that occasionally causes fatal systemic complications. We recently developed a tetravalent peptide (PPP-tet) that neutralizes the cytotoxicity of Stx2 using a multivalent peptide library approach. In this study, we used this technique to identify a series of tetravalent peptides that bound to Stx1, another major Stx family member, with high affinity by targeting one receptor-binding site of the B subunit. One peptide, MMA-tet, markedly inhibited Stx1 and Stx2 cytotoxicity with greater potency than PPP-tet. After forming a complex with Stx1 through its specific receptor-binding region, MMA-tet did not affect vesicular transport of the toxin to the endoplasmic reticulum but substantially rescued inhibition of the protein synthesis induced by Stx1. Oral application of MMA-tet protected mice from a fatal dose of an E. coli O157:H7 strain producing both toxins. MMA-tet may be a promising therapeutic agent against the infection.
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25
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Loś JM, Loś M, Węgrzyn A, Węgrzyn G. Altruism of Shiga toxin-producing Escherichia coli: recent hypothesis versus experimental results. Front Cell Infect Microbiol 2013; 2:166. [PMID: 23316482 PMCID: PMC3539655 DOI: 10.3389/fcimb.2012.00166] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 12/11/2012] [Indexed: 12/24/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) may cause bloody diarrhea and hemorrhagic colitis (HC), with subsequent systemic disease. Since genes coding for Shiga toxins (stx genes) are located on lambdoid prophages, their effective production occurs only after prophage induction. Such induction and subsequent lytic development of Shiga toxin-converting bacteriophages results not only in production of toxic proteins, but also in the lysis (and thus, the death) of the host cell. Therefore, one may ask the question: what is the benefit for bacteria to produce the toxin if they die due to phage production and subsequent cell lysis? Recently, a hypothesis was proposed (simultaneously but independently by two research groups) that STEC may benefit from Shiga toxin production as a result of toxin-dependent killing of eukaryotic cells such as unicellular predators or human leukocytes. This hypothesis could make sense only if we assume that prophage induction (and production of the toxin) occurs only in a small fraction of bacterial cells, thus, a few members of the population are sacrificed for the benefit of the rest, providing an example of “bacterial altruism.” However, various reports indicating that the frequency of spontaneous induction of Shiga toxin-converting prophages is higher than that of other lambdoid prophages might seem to contradict the for-mentioned model. On the other hand, analysis of recently published results, discussed here, indicated that the efficiency of prophage excision under conditions that may likely occur in the natural habitat of STEC is sufficiently low to ensure survival of a large fraction of the bacterial host. A molecular mechanism by which partial prophage induction may occur is proposed. We conclude that the published data supports the proposed model of bacterial “altruism” where prophage induction occurs at a low enough frequency to render toxin production a positive selective force on the general STEC population.
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Affiliation(s)
- Joanna M Loś
- Laboratory of Molecular Genetics, Department of Molecular Biology, University of Gdańsk Gdańsk, Poland
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Shi PL, Binnington B, Sakac D, Katsman Y, Ramkumar S, Gariepy J, Kim M, Branch DR, Lingwood C. Verotoxin A subunit protects lymphocytes and T cell lines against X4 HIV infection in vitro. Toxins (Basel) 2012; 4:1517-34. [PMID: 23242319 PMCID: PMC3528260 DOI: 10.3390/toxins4121517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 11/24/2012] [Accepted: 12/06/2012] [Indexed: 11/23/2022] Open
Abstract
Our previous genetic, pharmacological and analogue protection studies identified the glycosphingolipid, Gb3 (globotriaosylceramide, Pk blood group antigen) as a natural resistance factor for HIV infection. Gb3 is a B cell marker (CD77), but a fraction of activated peripheral blood mononuclear cells (PBMCs) can also express Gb3. Activated PBMCs predominantly comprise CD4+ T-cells, the primary HIV infection target. Gb3 is the sole receptor for Escherichia coli verotoxins (VTs, Shiga toxins). VT1 contains a ribosome inactivating A subunit (VT1A) non-covalently associated with five smaller receptor-binding B subunits. The effect of VT on PHA/IL2-activated PBMC HIV susceptibility was determined. Following VT1 (or VT2) PBMC treatment during IL2/PHA activation, the small Gb3+/CD4+ T-cell subset was eliminated but, surprisingly, remaining CD4+ T-cell HIV-1IIIB (and HIV-1Ba-L) susceptibility was significantly reduced. The Gb3-Jurkat T-cell line was similarly protected by brief VT exposure prior to HIV-1IIIB infection. The efficacy of the VT1A subunit alone confirmed receptor independent protection. VT1 showed no binding or obvious Jurkat cell/PBMC effect. Protective VT1 concentrations reduced PBMC (but not Jurkat cell) proliferation by 50%. This may relate to the mechanism of action since HIV replication requires primary T-cell proliferation. Microarray analysis of VT1A-treated PBMCs indicated up regulation of 30 genes. Three of the top four were histone genes, suggesting HIV protection via reduced gene activation. VT blocked HDAC inhibitor enhancement of HIV infection, consistent with a histone-mediated mechanism. We speculate that VT1A may provide a benign approach to reduction of (X4 or R5) HIV cell susceptibility.
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Affiliation(s)
- Pei Lin Shi
- Department of Biochemistry, University of Toronto, Ontario M5G 1X8, Canada; E-Mail:
- Division of Molecular Structure and Function and Research Institute, The Hospital for Sick Children, Ontario M5G 1X8, Canada; E-Mail:
| | - Beth Binnington
- Division of Molecular Structure and Function and Research Institute, The Hospital for Sick Children, Ontario M5G 1X8, Canada; E-Mail:
| | - Darinka Sakac
- Canadian Blood Services, Toronto, Ontario M5G 2M1, Canada; E-Mails: (D.S.); (Y.K.)
| | - Yulia Katsman
- Canadian Blood Services, Toronto, Ontario M5G 2M1, Canada; E-Mails: (D.S.); (Y.K.)
| | - Stephanie Ramkumar
- Laboratory Medicine & Pathology, University of Toronto, Ontario M5G 1X8, Canada; E-Mails: (S.R.); (M.K.); (D.R.B.)
| | - Jean Gariepy
- Department of Medical Biophysics & Pharmaceutical Sciences, University of Toronto, Ontario M5G 1X8, Canada; E-Mail:
- Sunnybrook Research Institute, Sunnybrook Health Science Centre, Toronto M4N 3M5, Canada
| | - Minji Kim
- Canadian Blood Services, Toronto, Ontario M5G 2M1, Canada; E-Mails: (D.S.); (Y.K.)
- Laboratory Medicine & Pathology, University of Toronto, Ontario M5G 1X8, Canada; E-Mails: (S.R.); (M.K.); (D.R.B.)
| | - Donald R. Branch
- Canadian Blood Services, Toronto, Ontario M5G 2M1, Canada; E-Mails: (D.S.); (Y.K.)
- Laboratory Medicine & Pathology, University of Toronto, Ontario M5G 1X8, Canada; E-Mails: (S.R.); (M.K.); (D.R.B.)
- Department of Medicine, University of Toronto, Ontario M5G 1X8, Canada
- Division of Cell and Molecular Biology, Toronto General Research Institute of the University Health Network, Toronto, Ontario M5G 2M9, Canada
| | - Clifford Lingwood
- Department of Biochemistry, University of Toronto, Ontario M5G 1X8, Canada; E-Mail:
- Division of Molecular Structure and Function and Research Institute, The Hospital for Sick Children, Ontario M5G 1X8, Canada; E-Mail:
- Laboratory Medicine & Pathology, University of Toronto, Ontario M5G 1X8, Canada; E-Mails: (S.R.); (M.K.); (D.R.B.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-416-813-5998; Fax: +1-416-813-5993
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Stone SM, Thorpe CM, Ahluwalia A, Rogers AB, Obata F, Vozenilek A, Kolling GL, Kane AV, Magun BE, Jandhyala DM. Shiga toxin 2-induced intestinal pathology in infant rabbits is A-subunit dependent and responsive to the tyrosine kinase and potential ZAK inhibitor imatinib. Front Cell Infect Microbiol 2012; 2:135. [PMID: 23162799 PMCID: PMC3492723 DOI: 10.3389/fcimb.2012.00135] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 10/15/2012] [Indexed: 11/13/2022] Open
Abstract
Shiga toxin producing Escherichia coli (STEC) are a major cause of food-borne illness worldwide. However, a consensus regarding the role Shiga toxins play in the onset of diarrhea and hemorrhagic colitis (HC) is lacking. One of the obstacles to understanding the role of Shiga toxins to STEC-mediated intestinal pathology is a deficit in small animal models that perfectly mimic human disease. Infant rabbits have been previously used to study STEC and/or Shiga toxin-mediated intestinal inflammation and diarrhea. We demonstrate using infant rabbits that Shiga toxin-mediated intestinal damage requires A-subunit activity, and like the human colon, that of the infant rabbit expresses the Shiga toxin receptor Gb(3). We also demonstrate that Shiga toxin treatment of the infant rabbit results in apoptosis and activation of p38 within colonic tissues. Finally we demonstrate that the infant rabbit model may be used to test candidate therapeutics against Shiga toxin-mediated intestinal damage. While the p38 inhibitor SB203580 and the ZAK inhibitor DHP-2 were ineffective at preventing Shiga toxin-mediated damage to the colon, pretreatment of infant rabbits with the drug imatinib resulted in a decrease of Shiga toxin-mediated heterophil infiltration of the colon. Therefore, we propose that this model may be useful in elucidating mechanisms by which Shiga toxins could contribute to intestinal damage in the human.
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Affiliation(s)
- Samuel M Stone
- Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, and Tufts University School of Medicine Boston, MA, USA
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Bergan J, Dyve Lingelem AB, Simm R, Skotland T, Sandvig K. Shiga toxins. Toxicon 2012; 60:1085-107. [PMID: 22960449 DOI: 10.1016/j.toxicon.2012.07.016] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 06/19/2012] [Accepted: 07/25/2012] [Indexed: 02/03/2023]
Abstract
Shiga toxins are virulence factors produced by the bacteria Shigella dysenteriae and certain strains of Escherichia coli. There is currently no available treatment for disease caused by these toxin-producing bacteria, and understanding the biology of the Shiga toxins might be instrumental in addressing this issue. In target cells, the toxins efficiently inhibit protein synthesis by inactivating ribosomes, and they may induce signaling leading to apoptosis. To reach their cytoplasmic target, Shiga toxins are endocytosed and transported by a retrograde pathway to the endoplasmic reticulum, before the enzymatically active moiety is translocated to the cytosol. The toxins thereby serve as powerful tools to investigate mechanisms of intracellular transport. Although Shiga toxins are a serious threat to human health, the toxins may be exploited for medical purposes such as cancer therapy or imaging.
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Affiliation(s)
- Jonas Bergan
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Norway
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Li S, Spooner RA, Hampton RY, Lord JM, Roberts LM. Cytosolic entry of Shiga-like toxin a chain from the yeast endoplasmic reticulum requires catalytically active Hrd1p. PLoS One 2012; 7:e41119. [PMID: 22829918 PMCID: PMC3400632 DOI: 10.1371/journal.pone.0041119] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 06/19/2012] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Escherichia coli Shiga-like toxin 1 normally traffics to the endoplasmic reticulum (ER) in sensitive mammalian cells from where the catalytic A chain (SLTxA1) dislocates to the cytosol to inactivate ribosomes. Currently, no molecular details of the dislocation process are available. To investigate the mechanism of the dislocation step we expressed SLTxA1 in the ER of Saccharomyces cerevisiae. METHODOLOGY AND PRINCIPAL FINDINGS Using a combination of growth studies and biochemical tracking in yeast knock-out strains we show that SLTxA1 follows an ER-associated degradation (ERAD) pathway to enter the cytosol in a step mediated by the transmembrane Hrd1p ubiquitin ligase complex. ER-to-cytosol dislocation of the bulk population of SLTxA1 requires Cdc48p and its ubiquitin-handling co-factor Npl4p, and this population of toxin is terminally dispatched by proteasomal degradation. A small sub-population of SLTxA1 uncouples from this classical ERAD pathway and recovers catalytic activity in the cytosol. The pathway that leads to toxicity is also Hrd1p-dependent but, unlike that for the related ricin A chain toxin, SLTxA1 dislocation does require the catalytic cysteine of Hrd1p. However it does not depend on canonical ubiquitylation since toxin variants lacking endogenous lysyl residues also utilize this pathway, and furthermore there is no requirement for a number of Cdc48p co-factors. CONCLUSIONS AND SIGNIFICANCE The fraction of SLTxA1 that disengages from the ERAD pathway thus does so upstream of Cdc48p interactions and downstream of Hrd1p interactions, in a step that possibly involves de-ubiquitylation. Mechanistically therefore, the dislocation of this toxin is quite distinct from that of conventional ERAD substrates that are normally degraded, and the toxins partially characterised to date that do not require the catalytic cysteine of the major Hrd1p component of the dislocation apparatus.
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Affiliation(s)
- Shuyu Li
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Robert A. Spooner
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Randolph Y. Hampton
- Section of Cell and Developmental Biology, Division of Biology, University of California San Diego, La Jolla, California, United States of America
| | - J. Michael Lord
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Lynne M. Roberts
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail:
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Leyva-Illades D, Cherla RP, Lee MS, Tesh VL. Regulation of cytokine and chemokine expression by the ribotoxic stress response elicited by Shiga toxin type 1 in human macrophage-like THP-1 cells. Infect Immun 2012; 80:2109-20. [PMID: 22431646 PMCID: PMC3370584 DOI: 10.1128/iai.06025-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 03/04/2012] [Indexed: 01/20/2023] Open
Abstract
Shiga toxins (Stxs) are cytotoxins produced by the enteric pathogens Shigella dysenteriae serotype 1 and Shiga toxin-producing Escherichia coli (STEC). Stxs bind to a membrane glycolipid receptor, enter cells, and undergo retrograde transport to ultimately reach the cytosol, where the toxins exert their protein synthesis-inhibitory activity by depurination of a single adenine residue from the 28S rRNA component of eukaryotic ribosomes. The depurination reaction activates the ribotoxic stress response, leading to signaling via the mitogen-activated protein kinase (MAPK) pathways (Jun N-terminal protein kinase [JNK], p38, and extracellular signal-regulated kinase [ERK]) in human epithelial, endothelial, and myeloid cells. We previously showed that treatment of human macrophage-like THP-1 cells with Stxs resulted in increased cytokine and chemokine expression. In the present study, we show that individual inactivation of ERK, JNK, and p38 MAPKs using pharmacological inhibitors in the presence of Stx1 resulted in differential regulation of the cytokines tumor necrosis factor alpha and interleukin-1β (IL-1β) and chemokines IL-8, growth-regulated protein-β, macrophage inflammatory protein-1α (MIP-1α), and MIP-1β. THP-1 cells exposed to Stx1 upregulate the expression of select dual-specificity phosphatases (DUSPs), enzymes that dephosphorylate and inactivate MAPKs in mammalian cells. In this study, we confirmed DUSP1 protein production by THP-1 cells treated with Stx1. DUSP1 inhibition by triptolide showed that ERK and p38 phosphorylation is regulated by DUSP1, while JNK phosphorylation is not. Inhibition of p38 MAPK signaling blocked the ability of Stx1 to induce DUSP1 mRNA expression, suggesting that an autoregulatory signaling loop may be activated by Stxs. Thus, Stxs appear to be capable of eliciting signals which both activate and deactivate signaling for increased cytokine/chemokine production in human macrophage-like cells.
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Affiliation(s)
- Dinorah Leyva-Illades
- Department of Microbial and Molecular Pathogenesis, College of Medicine, Texas A&M Health Science Center, Bryan, Texas, USA
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Saito M, Mylvaganum M, Tam P, Novak A, Binnington B, Lingwood C. Structure-dependent pseudoreceptor intracellular traffic of adamantyl globotriaosyl ceramide mimics. J Biol Chem 2012; 287:16073-87. [PMID: 22418442 DOI: 10.1074/jbc.m111.318196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The verotoxin (VT) (Shiga toxin) receptor globotriaosyl ceramide (Gb(3)), mediates VT1/VT2 retrograde transport to the endoplasmic reticulum (ER) for cytosolic A subunit access to inhibit protein synthesis. Adamantyl Gb(3) is an amphipathic competitive inhibitor of VT1/VT2 Gb(3) binding. However, Gb(3)-negative VT-resistant CHO/Jurkat cells incorporate adaGb(3) to become VT1/VT2-sensitive. CarboxyadaGb(3), urea-adaGb(3), and hydroxyethyl adaGb(3), preferentially bound by VT2, also mediate VT1/VT2 cytotoxicity. VT1/VT2 internalize to early endosomes but not to Golgi/ER. AdabisGb(3) (two deacyl Gb(3)s linked to adamantane) protects against VT1/VT2 more effectively than adaGb(3) without incorporating into Gb(3)-negative cells. AdaGb(3) (but not hydroxyethyl adaGb(3)) incorporation into Gb(3)-positive Vero cells rendered punctate cell surface VT1/VT2 binding uniform and subverted subsequent Gb(3)-dependent retrograde transport to Golgi/ER to render cytotoxicity (reduced for VT1 but not VT2) brefeldin A-resistant. VT2-induced vacuolation was maintained in adaGb(3)-treated Vero cells, but vacuolar membrane VT2 was lost. AdaGb(3) destabilized membrane cholesterol and reduced Gb(3) cholesterol stabilization in phospholipid liposomes. Cholera toxin GM1-mediated Golgi/ER targeting was unaffected by adaGb(3). We demonstrate the novel, lipid-dependent, pseudoreceptor function of Gb(3) mimics and their structure-dependent modulation of endogenous intracellular Gb(3) vesicular traffic.
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Affiliation(s)
- Mitsumasa Saito
- Research Institute, Program in Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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McCluskey AJ, Bolewska-Pedyczak E, Jarvik N, Chen G, Sidhu SS, Gariépy J. Charged and hydrophobic surfaces on the a chain of shiga-like toxin 1 recognize the C-terminal domain of ribosomal stalk proteins. PLoS One 2012; 7:e31191. [PMID: 22355345 PMCID: PMC3280276 DOI: 10.1371/journal.pone.0031191] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 01/03/2012] [Indexed: 11/19/2022] Open
Abstract
Shiga-like toxins are ribosome-inactivating proteins (RIP) produced by pathogenic E. coli strains that are responsible for hemorrhagic colitis and hemolytic uremic syndrome. The catalytic A(1) chain of Shiga-like toxin 1 (SLT-1), a representative RIP, first docks onto a conserved peptide SD[D/E]DMGFGLFD located at the C-terminus of all three eukaryotic ribosomal stalk proteins and halts protein synthesis through the depurination of an adenine base in the sarcin-ricin loop of 28S rRNA. Here, we report that the A(1) chain of SLT-1 rapidly binds to and dissociates from the C-terminal peptide with a monomeric dissociation constant of 13 µM. An alanine scan performed on the conserved peptide revealed that the SLT-1 A(1) chain interacts with the anionic tripeptide DDD and the hydrophobic tetrapeptide motif FGLF within its sequence. Based on these 2 peptide motifs, SLT-1 A(1) variants were generated that displayed decreased affinities for the stalk protein C-terminus and also correlated with reduced ribosome-inactivating activities in relation to the wild-type A(1) chain. The toxin-peptide interaction and subsequent toxicity were shown to be mediated by cationic and hydrophobic docking surfaces on the SLT-1 catalytic domain. These docking surfaces are located on the opposite face of the catalytic cleft and suggest that the docking of the A(1) chain to SDDDMGFGLFD may reorient its catalytic domain to face its RNA substrate. More importantly, both the delineated A(1) chain ribosomal docking surfaces and the ribosomal peptide itself represent a target and a scaffold, respectively, for the design of generic inhibitors to block the action of RIPs.
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Affiliation(s)
- Andrew J. McCluskey
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
| | | | - Nick Jarvik
- Banting and Best Department of Medical Research, Terrence Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Gang Chen
- Banting and Best Department of Medical Research, Terrence Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Sachdev S. Sidhu
- Banting and Best Department of Medical Research, Terrence Donnelly Center for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Jean Gariépy
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
- Sunnybrook Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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Taylor M, Banerjee T, VanBennekom N, Teter K. Detection of toxin translocation into the host cytosol by surface plasmon resonance. J Vis Exp 2012:e3686. [PMID: 22231143 DOI: 10.3791/3686] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
AB toxins consist of an enzymatic A subunit and a cell-binding B subunit(1). These toxins are secreted into the extracellular milieu, but they act upon targets within the eukaryotic cytosol. Some AB toxins travel by vesicle carriers from the cell surface to the endoplasmic reticulum (ER) before entering the cytosol(2-4). In the ER, the catalytic A chain dissociates from the rest of the toxin and moves through a protein-conducting channel to reach its cytosolic target(5). The translocated, cytosolic A chain is difficult to detect because toxin trafficking to the ER is an extremely inefficient process: most internalized toxin is routed to the lysosomes for degradation, so only a small fraction of surface-bound toxin reaches the Golgi apparatus and ER(6-12). To monitor toxin translocation from the ER to the cytosol in cultured cells, we combined a subcellular fractionation protocol with the highly sensitive detection method of surface plasmon resonance (SPR)(13-15). The plasma membrane of toxin-treated cells is selectively permeabilized with digitonin, allowing collection of a cytosolic fraction which is subsequently perfused over an SPR sensor coated with an anti-toxin A chain antibody. The antibody-coated sensor can capture and detect pg/mL quantities of cytosolic toxin. With this protocol, it is possible to follow the kinetics of toxin entry into the cytosol and to characterize inhibitory effects on the translocation event. The concentration of cytosolic toxin can also be calculated from a standard curve generated with known quantities of A chain standards that have been perfused over the sensor. Our method represents a rapid, sensitive, and quantitative detection system that does not require radiolabeling or other modifications to the target toxin.
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Affiliation(s)
- Michael Taylor
- Department of Molecular Biology and Microbiology, University of Central Florida, USA
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Abstract
Shiga toxin-producing bacteria cause widespread outbreaks of bloody diarrhoea that may progress to life-threatening systemic complications. Shiga toxins (Stxs), the main virulence factors expressed by the pathogens, are ribosome-inactivating proteins which inhibit protein synthesis by removing an adenine residue from 28S rRNA. Recently, Stxs were shown to activate multiple stress-associated signalling pathways in mammalian cells. The ribotoxic stress response is activated following the depurination reaction localized to the α-sarcin/ricin loop of eukaryotic ribosomes. The unfolded protein response (UPR) may be initiated by toxin unfolding within the endoplasmic reticulum, and maintained by production of truncated, misfolded proteins following intoxication. Activation of the ribotoxic stress response leads to signalling through MAPK cascades, which appears to be critical for activation of innate immunity and regulation of apoptosis. Precise mechanisms linking ribosomal damage with MAPK activation require clarification but may involve recognition of ribosomal conformational changes and binding of protein kinases to ribosomes, which activate MAP3Ks and MAP2Ks. Stxs appear capable of activating all ER membrane localized UPR sensors. Prolonged signalling through the UPR induces apoptosis in some cell types. The characterization of stress responses activated by Stxs may identify targets for the development of interventional therapies to block cell damage and disease progression.
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Affiliation(s)
- Vernon L Tesh
- Department of Microbial and Molecular Pathogenesis, College of Medicine, Texas A&M Health Science Center, Bryan, TX 77807, USA.
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Aletrari MO, McKibbin C, Williams H, Pawar V, Pietroni P, Lord JM, Flitsch SL, Whitehead R, Swanton E, High S, Spooner RA. Eeyarestatin 1 interferes with both retrograde and anterograde intracellular trafficking pathways. PLoS One 2011; 6:e22713. [PMID: 21799938 PMCID: PMC3143184 DOI: 10.1371/journal.pone.0022713] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 06/28/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The small molecule Eeyarestatin I (ESI) inhibits the endoplasmic reticulum (ER)-cytosol dislocation and subsequent degradation of ERAD (ER associated protein degradation) substrates. Toxins such as ricin and Shiga/Shiga-like toxins (SLTx) are endocytosed and trafficked to the ER. Their catalytic subunits are thought to utilise ERAD-like mechanisms to dislocate from the ER into the cytosol, where a proportion uncouples from the ERAD process, recovers a catalytic conformation and destroys their cellular targets. We therefore investigated ESI as a potential inhibitor of toxin dislocation. METHODOLOGY AND PRINCIPAL FINDINGS Using cytotoxicity measurements, we found no role for ES(I) as an inhibitor of toxin dislocation from the ER, but instead found that for SLTx, ESI treatment of cells was protective by reducing the rate of toxin delivery to the ER. Microscopy of the trafficking of labelled SLTx and its B chain (lacking the toxic A chain) showed a delay in its accumulation at a peri-nuclear location, confirmed to be the Golgi by examination of SLTx B chain metabolically labelled in the trans-Golgi cisternae. The drug also reduced the rate of endosomal trafficking of diphtheria toxin, which enters the cytosol from acidified endosomes, and delayed the Golgi-specific glycan modifications and eventual plasma membrane appearance of tsO45 VSV-G protein, a classical marker for anterograde trafficking. CONCLUSIONS AND SIGNIFICANCE ESI acts on one or more components that function during vesicular transport, whilst at least one retrograde trafficking pathway, that of ricin, remains unperturbed.
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Affiliation(s)
- Mina-Olga Aletrari
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Craig McKibbin
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Helen Williams
- School of Chemistry, University of Manchester, Manchester, United Kingdom
| | - Vidya Pawar
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Paola Pietroni
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - J. Michael Lord
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Sabine L. Flitsch
- School of Chemistry, University of Manchester, Manchester, United Kingdom
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom
| | - Roger Whitehead
- School of Chemistry, University of Manchester, Manchester, United Kingdom
| | - Eileithyia Swanton
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Stephen High
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail: (RAS); (SH)
| | - Robert A. Spooner
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail: (RAS); (SH)
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Shiga toxin interaction with human intestinal epithelium. Toxins (Basel) 2011; 3:626-39. [PMID: 22069729 PMCID: PMC3202847 DOI: 10.3390/toxins3060626] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/02/2011] [Accepted: 06/07/2011] [Indexed: 02/03/2023] Open
Abstract
After ingestion via contaminated food or water, enterohaemorrhagic E. coli colonises the intestinal mucosa and produces Shiga toxins (Stx). No Stx-specific secretion system has been described so far, and it is assumed that Stx are released into the gut lumen after bacterial lysis. Human intestinal epithelium does not express the Stx receptor Gb3 or other Stx binding sites, and it remains unknown how Stx cross the intestinal epithelial barrier and gain access to the systemic circulation. This review summarises current knowledge about the influence of the intestinal environment on Stx production and release, Stx interaction with intestinal epithelial cells and intracellular uptake, and toxin translocation into underlying tissues. Furthermore, it highlights gaps in understanding that need to be addressed by future research.
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Spooner RA, Lord JM. How ricin and Shiga toxin reach the cytosol of target cells: retrotranslocation from the endoplasmic reticulum. Curr Top Microbiol Immunol 2011; 357:19-40. [PMID: 21761287 DOI: 10.1007/82_2011_154] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A number of protein toxins bind at the surface of mammalian cells and after endocytosis traffic to the endoplasmic reticulum, where the toxic A chains are liberated from the holotoxin. The free A chains are then dislocated, or retrotranslocated, across the ER membrane into the cytosol. Here, in contrast to ER substrates destined for proteasomal destruction, they undergo folding to a catalytic conformation and subsequently inactivate their cytosolic targets. These toxins therefore provide toxic probes for testing the molecular requirements for retrograde trafficking, the ER processes that prepare the toxic A chains for transmembrane transport, the dislocation step itself and for the post-dislocation folding that results in catalytic activity. We describe here the dislocation of ricin A chain and Shiga toxin A chain, but also consider cholera toxin which bears a superficial structural resemblance to Shiga toxin. Recent studies not only describe how these proteins breach the ER membrane, but also reveal aspects of a fundamental cell biological process, that of ER-cytosol dislocation.
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Affiliation(s)
- Robert A Spooner
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
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Mahfoud R, Manis A, Binnington B, Ackerley C, Lingwood CA. A major fraction of glycosphingolipids in model and cellular cholesterol-containing membranes is undetectable by their binding proteins. J Biol Chem 2010; 285:36049-59. [PMID: 20716521 PMCID: PMC2975227 DOI: 10.1074/jbc.m110.110189] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 07/23/2010] [Indexed: 11/06/2022] Open
Abstract
Glycosphingolipids (GSLs) accumulate in cholesterol-enriched cell membrane domains and provide receptors for protein ligands. Lipid-based "aglycone" interactions can influence GSL carbohydrate epitope presentation. To evaluate this relationship, Verotoxin binding its receptor GSL, globotriaosyl ceramide (Gb(3)), was analyzed in simple GSL/cholesterol, detergent-resistant membrane vesicles by equilibrium density gradient centrifugation. Vesicles separated into two Gb(3/)cholesterol-containing populations. The lighter, minor fraction (<5% total GSL), bound VT1, VT2, IgG/IgM mAb anti-Gb(3), HIVgp120 or Bandeiraea simplicifolia lectin. Only IgM anti-Gb(3), more tolerant of carbohydrate modification, bound both vesicle fractions. Post-embedding cryo-immuno-EM confirmed these results. This appears to be a general GSL-cholesterol property, because similar receptor-inactive vesicles were separated for other GSL-protein ligand systems; cholera toxin (CTx)-GM1, HIVgp120-galactosyl ceramide/sulfatide. Inclusion of galactosyl or glucosyl ceramide (GalCer and GlcCer) rendered VT1-unreactive Gb(3)/cholesterol vesicles, VT1-reactive. We found GalCer and GlcCer bind Gb(3), suggesting GSL-GSL interaction can counter cholesterol masking of Gb(3). The similar separation of Vero cell membrane-derived vesicles into minor "binding," and major "non-binding" fractions when probed with VT1, CTx, or anti-SSEA4 (a human GSL stem cell marker), demonstrates potential physiological relevance. Cell membrane GSL masking was cholesterol- and actin-dependent. Cholesterol depletion of Vero and HeLa cells enabled differential VT1B subunit labeling of "available" and "cholesterol-masked" plasma membrane Gb(3) pools by fluorescence microscopy. Thus, the model GSL/cholesterol vesicle studies predicted two distinct membrane GSL formats, which were demonstrated within the plasma membrane of cultured cells. Cholesterol masking of most cell membrane GSLs may impinge many GSL receptor functions.
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Affiliation(s)
- Radhia Mahfoud
- From the Division of Molecular Structure and Function, Research Institute, and
| | - Adam Manis
- From the Division of Molecular Structure and Function, Research Institute, and
- the Departments of Laboratory Medicine & Pathology and
| | - Beth Binnington
- From the Division of Molecular Structure and Function, Research Institute, and
| | - Cameron Ackerley
- the Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Ontario M5G 1X8 and
| | - Clifford A. Lingwood
- From the Division of Molecular Structure and Function, Research Institute, and
- the Department of Pediatric Laboratory Medicine, The Hospital for Sick Children, Ontario M5G 1X8 and
- the Departments of Laboratory Medicine & Pathology and
- Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Biochemical, pathological and oncological relevance of Gb3Cer receptor. Med Oncol 2010; 28 Suppl 1:S675-84. [PMID: 21069478 DOI: 10.1007/s12032-010-9732-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Accepted: 10/21/2010] [Indexed: 10/18/2022]
Abstract
Glycosphingolipids are amphipathic molecules composed of hydrophilic oligosaccharide chain and a hydrophobic ceramide part, located primarily in the membrane microdomains of animal cells. Their oligosaccharide chains make them excellent candidates for the cell surface recognition molecules. Natural glycosphingolipid, globotriaosylceramide (Gal α1-4, Gal β1-4, Glc β1-1, ceramide), is also called CD77 and its expression was previously associated with proliferating centroblasts undergoing somatic hypermutation, but it has been demonstrate that globotriaosylceramide is not a reliable marker to discriminate human centroblasts from centrocytes. Globotriaosylceramide constitutes rare P k blood group antigen on erythrocytes, and it is also known as Burkitt's lymphoma antigen. On endothelial cells, globotriaosylceramide plays as the receptor for bacterial toxins of the Shiga family, also called verotoxins. Precise biological function and significance of globotriaosylceramide expression on endothelial cells remains to be the subject of many studies and it is believed globotriaosylceramide represents an example of a glycolipid antigen able to transduce a signal leading to apoptosis. In past decade, cancer researches put a great afford in determining new therapeutic agents such as bacterial toxins against tumor malignancies. Reports have demonstrated that verotoxin-1 induces apoptosis in solid tumor cell lines expressing globotriaosylceramide such as astrocytoma, renal cell carcinoma, colon cancer and breast cancer due to verotoxin-1 high specificity and apoptosis-inducing properties, and therefore, it is suggested to be an anticancer agent. Verotoxins have been investigated weather they could reduce treatment side-effects and toxicity to normal tissues and become a new oncological tool in cancer labeling.
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Shiga toxins: intracellular trafficking to the ER leading to activation of host cell stress responses. Toxins (Basel) 2010; 2:1515-35. [PMID: 22069648 PMCID: PMC3153247 DOI: 10.3390/toxins2061515] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 05/18/2010] [Accepted: 06/01/2010] [Indexed: 12/25/2022] Open
Abstract
Despite efforts to improve hygenic conditions and regulate food and drinking water safety, the enteric pathogens, Shiga toxin-producing Escherichia coli (STEC) and Shigella dysenteriae serotype 1 remain major public health concerns due to widespread outbreaks and the severity of extra-intestinal diseases they cause, including acute renal failure and central nervous system complications. Shiga toxins are the key virulence factors expressed by these pathogens mediating extra-intestinal disease. Delivery of the toxins to the endoplasmic reticulum (ER) results in host cell protein synthesis inhibition, activation of the ribotoxic stress response, the ER stress response, and in some cases, the induction of apoptosis. Intrinsic and/or extrinsic apoptosis inducing pathways are involved in executing cell death following intoxication. In this review we provide an overview of the current understanding Shiga toxin intracellular trafficking, host cellular responses to the toxin and ER stress-induced apoptosis with an emphasis on recent findings.
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Global transcriptional response of macrophage-like THP-1 cells to Shiga toxin type 1. Infect Immun 2010; 78:2454-65. [PMID: 20351145 DOI: 10.1128/iai.01341-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Shiga toxins (Stxs) are bacterial cytotoxins produced by the enteric pathogens Shigella dysenteriae serotype 1 and some serotypes of Escherichia coli that cause bacillary dysentery and hemorrhagic colitis, respectively. To date, approaches to studying the capacity of Stxs to alter gene expression in intoxicated cells have been limited to individual genes. However, it is known that many of the signaling pathways activated by Stxs regulate the expression of multiple genes in mammalian cells. To expand the scope of analysis of gene expression and to better understand the underlying mechanisms for the various effects of Stxs on host cell functions, we carried out comparative microarray analyses to characterize the global transcriptional response of human macrophage-like THP-1 cells to Shiga toxin type 1 (Stx1) and lipopolysaccharides. The data were analyzed by using a rigorous combinatorial approach with three separate statistical algorithms. A total of 36 genes met the criteria of upregulated expression in response to Stx1 treatment, with 14 genes uniquely upregulated by Stx1. Microarray data were validated by real-time reverse transcriptase PCR for genes encoding early growth response 1 (Egr-1) (transcriptional regulator), cyclooxygenase 2 (COX-2; inflammation), and dual specificity phosphatase 1 (DUSP1), DUSP5, and DUSP10 (regulation of mitogen-activated protein kinase signaling). Stx1-mediated signaling through extracellular signal-regulated kinase 1/2 and Egr-1 appears to be involved in the increased expression and production of the proinflammatory mediator tumor necrosis factor alpha. Activation of COX-2 is associated with the increased production of proinflammatory and vasoactive eicosanoids. However, the capacity of Stx1 to increase the expression of genes encoding phosphatases suggests that mechanisms to dampen the macrophage proinflammatory response may be built into host response to the toxins.
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Distinct physiologic and inflammatory responses elicited in baboons after challenge with Shiga toxin type 1 or 2 from enterohemorrhagic Escherichia coli. Infect Immun 2010; 78:2497-504. [PMID: 20308301 DOI: 10.1128/iai.01435-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Shiga toxin-producing Escherichia coli is a principal source of regional outbreaks of bloody diarrhea and hemolytic-uremic syndrome in the United States and worldwide. Primary bacterial virulence factors are Shiga toxin types 1 and 2 (Stx1 and Stx2), and we performed parallel analyses of the pathophysiologies elicited by the toxins in nonhuman primate models to identify shared and unique consequences of the toxemias. After a single intravenous challenge with purified Stx1 or Stx2, baboons (Papio) developed thrombocytopenia, anemia, and acute renal failure with loss of glomerular function, in a dose-dependent manner. Differences in the timing and magnitude of physiologic responses were observed between the toxins. The animals were more sensitive to Stx2, with mortality at lower doses, but Stx2-induced renal injury and mortality were delayed 2 to 3 days compared to those after Stx1 challenge. Multiplex analyses of plasma inflammatory cytokines revealed similarities (macrophage chemoattractant protein 1 [MCP-1] and tumor necrosis factor alpha [TNF-alpha]) and differences (interleukin-6 [IL-6] and granulocyte colony-stimulating factor [G-CSF]) elicited by the toxins with respect to the mediator induced and timing of the responses. Neither toxin induced detectable levels of plasma TNF-alpha. To our knowledge, this is the first time that the in vivo consequences of the toxins have been compared in a parallel and reproducible manner in nonhuman primates, and the data show similarities to patient observations. The availability of experimental nonhuman primate models for Stx toxemias provides a reproducible platform for testing antitoxin compounds and immunotherapeutics with outcome criteria that have clinical meaning.
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Abstract
Shiga toxins comprise a family of structurally and functionally related protein toxins expressed by Shigella dysenteriae serotype 1 and multiple serotypes of Escherichia coli. While the capacity of Shiga toxins to inhibit protein synthesis by catalytic inactivation of eukaryotic ribosomes has been well described, it is also apparent that Shiga toxins trigger apoptosis in many cell types. This review presents evidence that Shiga toxins induce apoptosis of epithelial, endothelial, leukocytic, lymphoid and neuronal cells. Apoptotic signaling pathways activated by the toxins are reviewed with an emphasis on signaling mechanisms that are shared among different cell types. Data suggesting that Shiga toxins induce apoptosis through the endoplasmic reticulum stress response and clinical evidence demonstrating apoptosis in humans infected with Shiga toxin-producing bacteria are briefly discussed. The potential for use of Shiga toxins to induce apoptosis in cancer cells is briefly reviewed.
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Affiliation(s)
- Vernon L Tesh
- Department of Microbial & Molecular Pathogenesis, College of Medicine, Texas A&M University System Health Science Center, 407 Reynolds Medical Building, College Station, TX 77843-1114, USA.
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Lingwood CA, Manis A, Mahfoud R, Khan F, Binnington B, Mylvaganam M. New aspects of the regulation of glycosphingolipid receptor function. Chem Phys Lipids 2010; 163:27-35. [DOI: 10.1016/j.chemphyslip.2009.09.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 09/15/2009] [Accepted: 09/16/2009] [Indexed: 12/19/2022]
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Johannes L, Römer W. Shiga toxins--from cell biology to biomedical applications. Nat Rev Microbiol 2009; 8:105-16. [PMID: 20023663 DOI: 10.1038/nrmicro2279] [Citation(s) in RCA: 352] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Shiga toxin-producing Escherichia coli is an emergent pathogen that can induce haemolytic uraemic syndrome. The toxin has received considerable attention not only from microbiologists but also in the field of cell biology, where it has become a powerful tool to study intracellular trafficking. In this Review, we summarize the Shiga toxin family members and their structures, receptors, trafficking pathways and cellular targets. We discuss how Shiga toxin affects cells not only by inhibiting protein biosynthesis but also through the induction of signalling cascades that lead to apoptosis. Finally, we discuss how Shiga toxins might be exploited in cancer therapy and immunotherapy.
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Affiliation(s)
- Ludger Johannes
- Institut Curie - Centre de Recherche and CNRS UMR144, Traffic, Signalling and Delivery Laboratory, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
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Globotriaosyl ceramide receptor function - Where membrane structure and pathology intersect. FEBS Lett 2009; 584:1879-86. [DOI: 10.1016/j.febslet.2009.11.089] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 11/25/2009] [Accepted: 11/26/2009] [Indexed: 11/30/2022]
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Palermo MS, Exeni RA, Fernández GC. Hemolytic uremic syndrome: pathogenesis and update of interventions. Expert Rev Anti Infect Ther 2009; 7:697-707. [PMID: 19681698 DOI: 10.1586/eri.09.49] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The typical form of hemolytic uremic syndrome (HUS) is the major complication of Shiga toxin-producing Escherichia coli infections. HUS is a critical health problem in Argentina since it is the main cause of acute renal failure in children and the second cause of chronic renal failure, accounting for 20% of renal transplants in children and adolescents in Argentina. Despite extensive research in the field, the mainstay of treatment for patients with HUS is supportive therapy, and there are no specific therapies preventing or ameliorating the disease course. In this review, we present the current knowledge about pathogenic mechanisms and discuss traditional and innovative therapeutic approaches, with special focus in Argentinean contribution. The hope that a better understanding of transmission dynamics and pathogenesis of this disease will produce better therapies to prevent the acute mortality and the long-term morbidity of HUS is the driving force for intensified research.
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Affiliation(s)
- Marina S Palermo
- Lab Inmunologia, Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina P. de Melo 3081 (C1425AUM), Ciudad de Buenos Aires, Argentina.
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House B, Kus JV, Prayitno N, Mair R, Que L, Chingcuanco F, Gannon V, Cvitkovitch DG, Barnett Foster D. Acid-stress-induced changes in enterohaemorrhagic Escherichia coli O157 : H7 virulence. Microbiology (Reading) 2009; 155:2907-2918. [DOI: 10.1099/mic.0.025171-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) O157 : H7 is naturally exposed to a wide variety of stresses including gastric acid shock, and yet little is known about how this stress influences virulence. This study investigated the impact of acid stress on several critical virulence properties including survival, host adhesion, Shiga toxin production, motility and induction of host-cell apoptosis. Several acid-stress protocols with relevance for gastric passage as well as external environmental exposure were included. Acute acid stress at pH 3 preceded by acid adaptation at pH 5 significantly enhanced the adhesion of surviving organisms to epithelial cells and bacterial induction of host-cell apoptosis. Motility was also significantly increased after acute acid stress. Interestingly, neither secreted nor periplasmic levels of Shiga toxin were affected by acid shock. Pretreatment of bacteria with erythromycin eliminated the acid-induced adhesion enhancement, suggesting that de novo protein synthesis was required for the enhanced adhesion of acid-shocked organisms. DNA microarray was used to analyse the transcriptome of an EHEC O157 : H7 strain exposed to three different acid-stress treatments. Expression profiles of acid-stressed EHEC revealed significant changes in virulence factors associated with adhesion, motility and type III secretion. These results document profound changes in the virulence properties of EHEC O157 : H7 after acid stress, provide a comprehensive genetic analysis to substantiate these changes and suggest strategies that this pathogen may use during gastric passage and colonization in the human gastrointestinal tract.
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Affiliation(s)
- B. House
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - J. V. Kus
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - N. Prayitno
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - R. Mair
- Faculty of Dentistry, University of Toronto, Toronto, ON, Canada
| | - L. Que
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - F. Chingcuanco
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
| | - V. Gannon
- Public Health Agency of Canada, Lethbridge, Alberta, Canada
| | | | - D. Barnett Foster
- Department of Chemistry and Biology, Ryerson University, Toronto, ON M5B 2K3, Canada
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Detergent-resistant globotriaosyl ceramide may define verotoxin/glomeruli-restricted hemolytic uremic syndrome pathology. Kidney Int 2009; 75:1209-1216. [PMID: 19212418 DOI: 10.1038/ki.2009.7] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Verotoxin binding to its receptor, globotriaosyl ceramide(Gb(3)) mediates the glomerular pathology of hemolytic uremic syndrome, but Gb(3) is expressed in both tubular and glomerular cells. Gb(3) within detergent-resistant membranes, an index of glycolipid-cholesterol enriched lipid rafts, is required for in vitro cytotoxicity. We found that verotoxin 1 and 2 binding to human adult renal glomeruli is detergent resistant, whereas the strong verotoxin binding to renal tubules is detergent sensitive. Verotoxin binding to pediatric glomeruli was detergent resistant but binding to adult glomeruli was enhanced, remarkably for some samples, by detergent extraction. Detergent-sensitive glomerular components may provide age-related protection against verotoxin glomerular binding. Mouse glomeruli remained verotoxin unreactive after detergent extraction, whereas tubular binding was lost. Cholesterol extraction induced strong verotoxin binding in poorly reactive adult glomeruli, suggesting cholesterol can mask Gb(3) in glomerular lipid rafts. Binding of the human immunodeficiency virus (HIV) adhesin, gp120 (another Gb(3) ligand) was detergent sensitive, tubule-restricted, and inhibited by verotoxin B subunit pretreatment, and may relate to HIV nephropathy. Our study shows that differential membrane Gb(3) organization in glomeruli and tubules provides a basis for the age- and glomerular-restricted pathology of hemolytic uremic syndrome.
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Tam P, Mahfoud R, Nutikka A, Khine AA, Binnington B, Paroutis P, Lingwood C. Differential intracellular transport and binding of verotoxin 1 and verotoxin 2 to globotriaosylceramide-containing lipid assemblies. J Cell Physiol 2008; 216:750-63. [PMID: 18446787 DOI: 10.1002/jcp.21456] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Although verotoxin-1 (VT1) and verotoxin-2 (VT2) share a common receptor, globotriaosyl ceramide (Gb(3)), VT2 induces distinct animal pathology and is preferentially associated with human disease. Moreover VT2 cytotoxicity in vitro is less than VT1. We therefore investigated whether these toxins similarly traffic within cells via similar Gb(3) assemblies. At 4 degrees C, fluorescent-VT1 and VT2 bound both coincident and distinct punctate surface Gb(3) microdomains. After 10 min at 37 degrees C, similar distinct/coincident micropunctate intracellular localization was observed. Most internalized VT2, but not VT1, colocalized with transferrin. After 1 h, VT1 and VT2 coalesced during retrograde transport to the Golgi. During prolonged incubation (3-6 h), VT1, and VT2 (more slowly), exited the Golgi to reach the ER/nuclear envelope. At this time, VT2 induced a previously unreported, retrograde transport-dependent vacuolation. Cell surface and intracellular VT1 showed greater detergent resistance than VT2, suggesting differential 'raft' association. >90% (125)I-VT1 cell surface bound, or added to detergent-resistant cell membrane extracts (DRM), was in the Gb(3)-containing sucrose gradient 'insoluble' fraction, whereas only 30% (125)I-VT2 was similarly DRM-associated. VT1 bound more efficiently to Gb(3)/cholesterol DRMs generated in vitro. Only VT1 binding was inhibited by high cholesterol/Gb(3) ratios. VT2 competed less effectively for (125)I-VT1/Gb(3) DRM-binding but only VT2-Gb(3)/cholesterol DRM-binding was augmented by sphingomyelin. Differential VT1/VT2 Gb(3) raft-binding may mediate differential cell binding/intracellular trafficking and cytopathology.
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Affiliation(s)
- Patty Tam
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
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