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Boesze-Battaglia K, Cohen GH, Bates PF, Walker LM, Zekavat A, Shenker BJ. Cellugyrin (synaptogyrin-2) dependent pathways are used by bacterial cytolethal distending toxin and SARS-CoV-2 virus to gain cell entry. Front Cell Infect Microbiol 2024; 14:1334224. [PMID: 38698905 PMCID: PMC11063343 DOI: 10.3389/fcimb.2024.1334224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 03/19/2024] [Indexed: 05/05/2024] Open
Abstract
Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is capable of intoxicating lymphocytes macrophages, mast cells and epithelial cells. Following Cdt binding to cholesterol, in the region of membrane lipid rafts, the CdtB and CdtC subunits are internalized and traffic to intracellular compartments. These events are dependent upon, cellugyrin, a critical component of synaptic like microvesicles (SLMVCg+). Target cells, such as Jurkat cells, rendered unable to express cellugyrin are resistant to Cdt-induced toxicity. Similar to Cdt, SARS-CoV-2 entry into host cells is initiated by binding to cell surface receptors, ACE-2, also associated with cholesterol-rich lipid rafts; this association leads to fusion and/or endocytosis of viral and host cell membranes and intracellular trafficking. The similarity in internalization pathways for both Cdt and SARS-CoV-2 led us to consider the possibility that cellugyrin was a critical component in both processes. Cellugyrin deficient Calu-3 cells (Calu-3Cg-) were prepared using Lentiviral particles containing shRNA; these cells were resistant to infection by VSV/SARS-CoV-2-spike pseudotype virus and partially resistant to VSV/VSV-G pseudotype virus. Synthetic peptides representing various regions of the cellugyrin protein were prepared and assessed for their ability to bind to Cdt subunits using surface plasmon resonance. Cdt was capable of binding to a region designated the middle outer loop (MOL) which corresponds to a region extending into the cytoplasmic surface of the SLMVCg+. SARS-CoV-2 spike proteins were assessed for their ability to bind to cellugyrin peptides; SARS-CoV-2 full length spike protein preferentially binds to a region within the SLMVCg+ lumen, designated intraluminal loop 1A. SARS-CoV-2-spike protein domain S1, which contains the receptor binding domains, binds to cellugyrin N-terminus which extends out from the cytoplasmic surface of SLMV. Binding specificity was further analyzed using cellugyrin scrambled peptide mutants. We propose that SLMVCg+ represent a component of a common pathway that facilitates pathogen and/or pathogen-derived toxins to gain host cell entry.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Gary H. Cohen
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Paul F. Bates
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Lisa M. Walker
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Ali Zekavat
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Bruce J. Shenker
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
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Shenker BJ, Korostoff J, Walker LP, Zekavat A, Dhingra A, Kim TJ, Boesze-Battaglia K. Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Induces Cellugyrin-(Synaptogyrin 2) Dependent Cellular Senescence in Oral Keratinocytes. Pathogens 2024; 13:155. [PMID: 38392893 PMCID: PMC10892517 DOI: 10.3390/pathogens13020155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/25/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024] Open
Abstract
Recently, we reported that oral-epithelial cells (OE) are unique in their response to Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) in that cell cycle arrest (G2/M) occurs without leading to apoptosis. We now demonstrate that Cdt-induced cell cycle arrest in OE has a duration of at least 7 days with no change in viability. Moreover, toxin-treated OE develops a new phenotype consistent with cellular senescence; this includes increased senescence-associated β-galactosidase (SA-β-gal) activity and accumulation of the lipopigment, lipofuscin. Moreover, the cells exhibit a secretory profile associated with cellular senescence known as the senescence-associated secretory phenotype (SASP), which includes IL-6, IL-8 and RANKL. Another unique feature of Cdt-induced OE senescence is disruption of barrier function, as shown by loss of transepithelial electrical resistance and confocal microscopic assessment of primary gingival keratinocyte structure. Finally, we demonstrate that Cdt-induced senescence is dependent upon the host cell protein cellugyrin, a homologue of the synaptic vesicle protein synaptogyrin. Collectively, these observations point to a novel pathogenic outcome in oral epithelium that we propose contributes to both A. actinomycetemcomitans infection and periodontal disease progression.
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Affiliation(s)
- Bruce J. Shenker
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (L.P.W.); (A.Z.); (A.D.); (K.B.-B.)
| | - Jonathan Korostoff
- Department of Periodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (J.K.); (T.J.K.)
| | - Lisa P. Walker
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (L.P.W.); (A.Z.); (A.D.); (K.B.-B.)
| | - Ali Zekavat
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (L.P.W.); (A.Z.); (A.D.); (K.B.-B.)
| | - Anuradha Dhingra
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (L.P.W.); (A.Z.); (A.D.); (K.B.-B.)
| | - Taewan J. Kim
- Department of Periodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (J.K.); (T.J.K.)
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (L.P.W.); (A.Z.); (A.D.); (K.B.-B.)
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Kato I, Minkevitch J, Sun J. Oncogenic potential of Campylobacter infection in the gastrointestinal tract: narrative review. Scand J Gastroenterol 2023; 58:1453-1465. [PMID: 37366241 DOI: 10.1080/00365521.2023.2228954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/26/2023] [Accepted: 06/16/2023] [Indexed: 06/28/2023]
Abstract
BACKGROUND Campylobacter jejuni is the leading cause of zoonotic gastroenteritis. The other emerging group of Campylobacters spp. are part of human oral commensal, represented by C. concisus (CC), which has been recently linked to non-oral conditions. Although long-term gastrointestinal (GI) complications from these two groups of Campylobacters have been previously reviewed individually, overall impact of Campylobacter infection on GI carcinogenesis and their inflammatory precursor lesions has not been assessed collectively. AIMS To evaluate the available evidence concerning the association between Campylobacter infection/colonization and inflammatory bowel disease (IBD), reflux esophagitis/metaplasia colorectal cancer (CRC) and esophageal cancer (EC). METHODS We performed a comprehensive literature search of PubMed for relevant original publications and systematic reviews/meta-analyses of epidemiological and clinical studies. In addition, we gathered additional information concerning microbiological data, animal models and mechanistic data from in vitro studies. RESULTS Both retrospective and prospective studies on IBD showed relatively consistent increased risk associated with Campylobacter infection. Despite lack of supporting prospective studies, retrospective studies based on tissue/fecal microbiome revealed consistent enrichment of Campylobacter in CRC samples. Studies on EC precursor lesions (esophagitis and metaplasia) were generally supportive for the association with Campylobacter, while inconsistent observations on EC. Studies on both IBD and EC precursors suggested the predominant role of CC, but studies on CRC were not informative of species. CONCLUSIONS There is sufficient evidence calling for concerted effort in unveiling direct and indirect connection of this organism to colorectal and esophageal cancer in humans.
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Affiliation(s)
- Ikuko Kato
- Department of Oncology and Pathology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Julia Minkevitch
- Rosalind Franklin University of Medicine and Science, Chicago, IL, USA
| | - Jun Sun
- Department of Microbiology/Immunology, University of Illinois at Chicago (UIC), Chicago, IL, USA
- UIC Cancer Center, Chicago, IL, USA
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Abstract
Bacterial genotoxins are peptide or protein virulence factors produced by several pathogens, which make single-strand breaks (SSBs) and/or double-strand DNA breaks (DSBs) in the target host cells. If host DNA inflictions are not resolved on time, host cell apoptosis, cell senescence, and/or even bacterial pathogen-related cancer may occur. Two multi-protein AB toxins, cytolethal distending toxin (CDT) produced by over 30 bacterial pathogens and typhoid toxin from Salmonella Typhi, as well as small polyketide-peptides named colibactin that causes the DNA interstrand cross-linking and subsequent DSBs is the most well-characterized bacterial genotoxins. Using these three examples, this review discusses the mechanisms by which these toxins deliver themselves into the nucleus of the target host cells and exert their genotoxic functions at the structural and functional levels.
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Affiliation(s)
- Liaoqi Du
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
| | - Jeongmin Song
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY 14853, USA
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Kato I, Zhang J, Sun J. Bacterial-Viral Interactions in Human Orodigestive and Female Genital Tract Cancers: A Summary of Epidemiologic and Laboratory Evidence. Cancers (Basel) 2022; 14:425. [PMID: 35053587 PMCID: PMC8773491 DOI: 10.3390/cancers14020425] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 02/04/2023] Open
Abstract
Infectious agents, including viruses, bacteria, fungi, and parasites, have been linked to pathogenesis of human cancers, whereas viruses and bacteria account for more than 99% of infection associated cancers. The human microbiome consists of not only bacteria, but also viruses and fungi. The microbiome co-residing in specific anatomic niches may modulate oncologic potentials of infectious agents in carcinogenesis. In this review, we focused on interactions between viruses and bacteria for cancers arising from the orodigestive tract and the female genital tract. We examined the interactions of these two different biological entities in the context of human carcinogenesis in the following three fashions: (1) direct interactions, (2) indirect interactions, and (3) no interaction between the two groups, but both acting on the same host carcinogenic pathways, yielding synergistic or additive effects in human cancers, e.g., head and neck cancer, liver cancer, colon cancer, gastric cancer, and cervical cancer. We discuss the progress in the current literature and summarize the mechanisms of host-viral-bacterial interactions in various human cancers. Our goal was to evaluate existing evidence and identify gaps in the knowledge for future directions in infection and cancer.
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Affiliation(s)
- Ikuko Kato
- Department of Oncology and Pathology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Jilei Zhang
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, IL 60612, USA;
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Jun Sun
- Department of Medicine, Division of Gastroenterology and Hepatology, University of Illinois at Chicago, Chicago, IL 60612, USA;
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL 60612, USA
- UIC Cancer Center, University of Illinois at Chicago, Chicago, IL 60612, USA
- Jesse Brown VA Medical Center, Chicago, IL 60612, USA
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Engineering of Cytolethal Distending Toxin B by Its Reducing Immunogenicity and Maintaining Stability as a New Drug Candidate for Tumor Therapy; an In Silico Study. Toxins (Basel) 2021; 13:toxins13110785. [PMID: 34822569 PMCID: PMC8624547 DOI: 10.3390/toxins13110785] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 10/30/2021] [Accepted: 11/01/2021] [Indexed: 12/25/2022] Open
Abstract
The cytolethal distending toxin (CDT), Haemophilus ducreyi, is one of the bacterial toxins that have recently been considered for targeted therapies, especially in cancer therapies. CDT is an A-B2 exotoxin. Its catalytic subunit (CdtB) is capable of inducing DNA double strand breaks, cell cycle arrest and apoptosis in host eukaryotic cells. The sequence alignment indicates that the CdtB is structurally homologyr to phosphatases and deoxyribonucleases I (DNase I). Recently, it has been found that CdtB toxicity is mainly related to its nuclease activity. The immunogenicity of CDT can reduce its effectiveness in targeted therapies. However, the toxin can be very useful if its immunogenicity is significantly reduced. Detecting hotspot ectopic residues by computational servers and then mutating them to eliminate B-cell epitopes is a promising approach to reduce the immunogenicity of foreign protein-based therapeutics. By the mentioned method, in this study, we try to reduce the immunogenicity of the CdtB- protein sequence. This study initially screened residue of the CdtB is B-cell epitopes both linearly and conformationally. By overlapping the B-cell epitopes with the excluded conserve residues, and active and enzymatic sites, four residues were allowed to be mutated. There were two mutein options that show reduced antigenicity probability. Option one was N19F, G74I, and S161F with a VaxiJen score of 0.45 and the immune epitope database (IEDB) score of 1.80, and option two was N19F, G74I, and S161W with a VaxiJen score of 0.45 and IEDB score of 1.88. The 3D structure of the proposed sequences was evaluated and refined. The structural stability of native and mutant proteins was accessed through molecular dynamic simulation. The results showed that the mutations in the mutants caused no considerable changes in their structural stability. However, mutant 1 reveals more thermodynamic stability during the simulation. The applied approaches in this study can be used as rough guidelines for finding hot spot immunogen regions in the therapeutic proteins. Our results provide a new version of CdtB that, due to reduced immunogenicity and increased stability, can be used in toxin-based drugs such as immunotoxins.
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Varon C, Azzi-Martin L, Khalid S, Seeneevassen L, Ménard A, Spuul P. Helicobacters and cancer, not only gastric cancer? Semin Cancer Biol 2021; 86:1138-1154. [PMID: 34425210 DOI: 10.1016/j.semcancer.2021.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 12/11/2022]
Abstract
The Helicobacter genus actually comprises 46 validly published species divided into two main clades: gastric and enterohepatic Helicobacters. These bacteria colonize alternative sites of the digestive system in animals and humans, and contribute to inflammation and cancers. In humans, Helicobacter infection is mainly related to H. pylori, a gastric pathogen infecting more than half of the world's population, leading to chronic inflammation of the gastric mucosa that can evolve into two types of gastric cancers: gastric adenocarcinomas and gastric MALT lymphoma. In addition, H. pylori but also non-H. pylori Helicobacter infection has been associated with many extra-gastric malignancies. This review focuses on H. pylori and its role in gastric cancers and extra-gastric diseases, as well as malignancies induced by non-H. pylori Helicobacters. Their different virulence factors and their involvement in carcinogenesis is discussed. This review highlights the importance of both gastric and enterohepatic Helicobacters in gastrointestinal and liver cancers.
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Affiliation(s)
- Christine Varon
- Univ. Bordeaux, INSERM, UMR1053 Bordeaux Research in Translational Oncology, BaRITOn, Bordeaux, France
| | - Lamia Azzi-Martin
- Univ. Bordeaux, INSERM, UMR1053 Bordeaux Research in Translational Oncology, BaRITOn, Bordeaux, France; Univ. Bordeaux, UFR des Sciences Médicales, Bordeaux, France
| | - Sadia Khalid
- Tallinn University of Technology, Department of Chemistry and Biotechnology, Akadeemia RD 15, 12618, Tallinn, Estonia
| | - Lornella Seeneevassen
- Univ. Bordeaux, INSERM, UMR1053 Bordeaux Research in Translational Oncology, BaRITOn, Bordeaux, France
| | - Armelle Ménard
- Univ. Bordeaux, INSERM, UMR1053 Bordeaux Research in Translational Oncology, BaRITOn, Bordeaux, France
| | - Pirjo Spuul
- Tallinn University of Technology, Department of Chemistry and Biotechnology, Akadeemia RD 15, 12618, Tallinn, Estonia.
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Cytolethal distending toxin: from genotoxin to a potential biomarker and anti-tumor target. World J Microbiol Biotechnol 2021; 37:150. [PMID: 34379213 DOI: 10.1007/s11274-021-03117-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/31/2021] [Indexed: 10/20/2022]
Abstract
Cytolethal Distending Toxin (CDT) belongs to the AB toxin family and is produced by a plethora of Gram-negative bacteria. Eight human-affecting enteropathogens harbor CDT that causes irritable bowel syndrome (IBS), dysentery, chancroid, and periodontitis worldwide. They have a novel molecular mode of action as they interfere in the eukaryotic cell-cycle progression leading to G2/M arrest and apoptosis. CDT, the first bacterial genotoxin described, is encoded in a single operon possessing three proteins, CdtA, CdtB, and CdtC. CdtA and CdtC are needed for the binding of the CDT toxin complex to the cholesterol-rich lipid domains of the host cell while the CdtB is the active moiety. Sequence and 3D structural-based analysis of CdtB showed similarities with nucleases and phosphatases, it was hypothesized that CdtB exercises a biochemical function identical to both these enzymes. CDT is secreted through the outer membrane vesicles from the producing bacteria. It is internalized in the target cells via clathrin-dependent endocytosis and translocated to the host cell nucleus through the Golgi complex and ER. This study discusses the virulence role of CDT, causing pathogenicity by acting as a tri-perditious complex in the CDT-producing species with an emphasis on its potential role as a biomarker and an anti-tumor agent.
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Ochoa S, Collado L. Enterohepatic Helicobacter species - clinical importance, host range, and zoonotic potential. Crit Rev Microbiol 2021; 47:728-761. [PMID: 34153195 DOI: 10.1080/1040841x.2021.1924117] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The genus Helicobacter defined just over 30 years ago, is a highly diverse and fast-growing group of bacteria that are able to persistently colonize a wide range of animals. The members of this genus are subdivided into two groups with different ecological niches, associated pathologies, and phylogenetic relationships: the gastric Helicobacter (GH) and the enterohepatic Helicobacter (EHH) species. Although GH have been mostly studied, EHH species have become increasingly important as emerging human pathogens and potential zoonotic agents in the last years. This group of bacteria has been associated with the development of several diseases in humans from acute pathologies like gastroenteritis to chronic pathologies that include inflammatory bowel disease, and liver and gallbladder diseases. However, their reservoirs, as well as their routes of transmission, have not been well established yet. Therefore, this review summarizes the current knowledge of taxonomy, epidemiology, and clinical role of the EHH group.
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Affiliation(s)
- Sofia Ochoa
- Faculty of Sciences, Institute of Biochemistry and Microbiology, Universidad Austral de Chile, Valdivia, Chile.,ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
| | - Luis Collado
- Faculty of Sciences, Institute of Biochemistry and Microbiology, Universidad Austral de Chile, Valdivia, Chile.,ANID - Millennium Science Initiative Program - Millennium Nucleus in the Biology of the Intestinal Microbiota, Santiago, Chile
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Mathiasen SL, Gall-Mas L, Pateras IS, Theodorou SDP, Namini MRJ, Hansen MB, Martin OCB, Vadivel CK, Ntostoglou K, Butter D, Givskov M, Geisler C, Akbar AN, Gorgoulis VG, Frisan T, Ødum N, Krejsgaard T. Bacterial genotoxins induce T cell senescence. Cell Rep 2021; 35:109220. [PMID: 34107253 DOI: 10.1016/j.celrep.2021.109220] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 02/16/2021] [Accepted: 05/14/2021] [Indexed: 12/11/2022] Open
Abstract
Several types of pathogenic bacteria produce genotoxins that induce DNA damage in host cells. Accumulating evidence suggests that a central function of these genotoxins is to dysregulate the host's immune response, but the underlying mechanisms remain unclear. To address this issue, we investigated the effects of the most widely expressed bacterial genotoxin, the cytolethal distending toxin (CDT), on T cells-the key mediators of adaptive immunity. We show that CDT induces premature senescence in activated CD4 T cells in vitro and provide evidence suggesting that infection with genotoxin-producing bacteria promotes T cell senescence in vivo. Moreover, we demonstrate that genotoxin-induced senescent CD4 T cells assume a senescence-associated secretory phenotype (SASP) which, at least partly, is orchestrated by the ATM-p38 signaling axis. These findings provide insight into the immunomodulatory properties of bacterial genotoxins and uncover a putative link between bacterial infections and T cell senescence.
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Affiliation(s)
- Sarah L Mathiasen
- LEO Foundation Skin Immunology Research Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Laura Gall-Mas
- LEO Foundation Skin Immunology Research Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Ioannis S Pateras
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, National Kapodistrian University of Athens, 11527 Athens, Greece
| | - Sofia D P Theodorou
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, National Kapodistrian University of Athens, 11527 Athens, Greece
| | - Martin R J Namini
- LEO Foundation Skin Immunology Research Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Morten B Hansen
- Department of Clinical Immunology, Rigshospitalet, Copenhagen University Hospital, 2100 Copenhagen, Denmark
| | - Océane C B Martin
- Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Chella Krishna Vadivel
- LEO Foundation Skin Immunology Research Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Konstantinos Ntostoglou
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, National Kapodistrian University of Athens, 11527 Athens, Greece
| | - Deborah Butter
- Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Michael Givskov
- Costerton Biofilm Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Carsten Geisler
- LEO Foundation Skin Immunology Research Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Arne N Akbar
- Division of Medicine, University College London, London WC1E 6JF, UK
| | - Vassilis G Gorgoulis
- Molecular Carcinogenesis Group, Department of Histology and Embryology, School of Medicine, National Kapodistrian University of Athens, 11527 Athens, Greece; Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece; Faculty Institute for Cancer Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester M13 9PL, UK
| | - Teresa Frisan
- Department of Cell and Molecular Biology, Karolinska Institutet, 17177 Stockholm, Sweden; Department of Molecular Biology and Umeå Center for Microbial Research (UCMR), Umeå University, 90187 Umeå, Sweden
| | - Niels Ødum
- LEO Foundation Skin Immunology Research Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Thorbjørn Krejsgaard
- LEO Foundation Skin Immunology Research Center, Department of Immunology and Microbiology, University of Copenhagen, 2200 Copenhagen, Denmark.
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Huang G, Boesze-Battaglia K, Walker LP, Zekavat A, Schaefer ZP, Blanke SR, Shenker BJ. The Active Subunit of the Cytolethal Distending Toxin, CdtB, Derived From Both Haemophilus ducreyi and Campylobacter jejuni Exhibits Potent Phosphatidylinositol-3,4,5-Triphosphate Phosphatase Activity. Front Cell Infect Microbiol 2021; 11:664221. [PMID: 33854985 PMCID: PMC8039388 DOI: 10.3389/fcimb.2021.664221] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/09/2021] [Indexed: 12/17/2022] Open
Abstract
Human lymphocytes exposed to Aggregatibacter actinomycetemcomitans (Aa) cytolethal distending toxin (Cdt) undergo cell cycle arrest and apoptosis. In previous studies, we demonstrated that the active Cdt subunit, CdtB, is a potent phosphatidylinositol (PI) 3,4,5-triphosphate phosphatase. Moreover, AaCdt-treated cells exhibit evidence of PI-3-kinase (PI-3K) signaling blockade characterized by reduced levels of PIP3, pAkt, and pGSK3β. We have also demonstrated that PI-3K blockade is a requisite of AaCdt-induced toxicity in lymphocytes. In this study, we extended our observations to include assessment of Cdts from Haemophilus ducreyi (HdCdt) and Campylobacter jejuni (CjCdt). We now report that the CdtB subunit from HdCdt and CjCdt, similar to that of AaCdt, exhibit potent PIP3 phosphatase activity and that Jurkat cells treated with these Cdts exhibit PI-3K signaling blockade: reduced levels of pAkt and pGSK3β. Since non-phosphorylated GSK3β is the active form of this kinase, we compared Cdts for dependence on GSK3β activity. Two GSK3β inhibitors were employed, LY2090314 and CHIR99021; both inhibitors blocked the ability of Cdts to induce cell cycle arrest. We have previously demonstrated that AaCdt induces increases in the CDK inhibitor, p21CIP1/WAF1, and, further, that this was a requisite for toxin-induced cell death via apoptosis. We now demonstrate that HdCdt and CjCdt also share this requirement. It is also noteworthy that p21CIP1/WAF1 was not involved in the ability of the three Cdts to induce cell cycle arrest. Finally, we demonstrate that, like AaCdt, HdCdt is dependent upon the host cell protein, cellugyrin, for its toxicity (and presumably internalization of CdtB); CjCdt was not dependent upon this protein. The implications of these findings as they relate to Cdt’s molecular mode of action are discussed.
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Affiliation(s)
- Grace Huang
- Department of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United States
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United States
| | - Lisa P Walker
- Department of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United States
| | - Ali Zekavat
- Department of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United States
| | - Zachary P Schaefer
- Department of Microbiology, University of Illinois, Urbana, IL, United States
| | - Steven R Blanke
- Department of Microbiology, University of Illinois, Urbana, IL, United States.,Pathobiology Department, University of Illinois, Urbana, IL, United States.,Biomedical and Translational Sciences Department, University of Illinois, Urbana, IL, United States
| | - Bruce J Shenker
- Department of Basic and Translational Sciences, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, United States
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12
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Pons BJ, Loiseau N, Hashim S, Tadrist S, Mirey G, Vignard J. Functional Study of Haemophilus ducreyi Cytolethal Distending Toxin Subunit B. Toxins (Basel) 2020; 12:toxins12090530. [PMID: 32825080 PMCID: PMC7551728 DOI: 10.3390/toxins12090530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/13/2020] [Accepted: 08/17/2020] [Indexed: 12/17/2022] Open
Abstract
The Cytolethal Distending Toxin (CDT) is produced by many Gram-negative pathogenic bacteria responsible for major foodborne diseases worldwide. CDT induces DNA damage and cell cycle arrest in host-cells, eventually leading to senescence or apoptosis. According to structural and sequence comparison, the catalytic subunit CdtB is suggested to possess both nuclease and phosphatase activities, carried by a single catalytic site. However, the impact of each activity on cell-host toxicity is yet to be characterized. Here, we analyze the consequences of cell exposure to different CDT mutated on key CdtB residues, focusing on cell viability, cell cycle defects, and DNA damage induction. A first class of mutant, devoid of any activity, targets putative catalytic (H160A), metal binding (D273R), and DNA binding residues (R117A-R144A-N201A). The second class of mutants (A163R, F156-T158, and the newly identified G114T), which gathers mutations on residues potentially involved in lipid substrate binding, has only partially lost its toxic effects. However, their defects are alleviated when CdtB is artificially introduced inside cells, except for the F156-T158 double mutant that is defective in nuclear addressing. Therefore, our data reveal that CDT toxicity is mainly correlated to CdtB nuclease activity, whereas phosphatase activity may probably be involved in CdtB intracellular trafficking.
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Affiliation(s)
| | | | | | | | - Gladys Mirey
- Correspondence: (G.M.); (J.V.); Tel.: +33-582-066-338 (G.M.)
| | - Julien Vignard
- Correspondence: (G.M.); (J.V.); Tel.: +33-582-066-338 (G.M.)
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13
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Silbergleit M, Vasquez AA, Miller CJ, Sun J, Kato I. Oral and intestinal bacterial exotoxins: Potential linked to carcinogenesis. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 171:131-193. [PMID: 32475520 DOI: 10.1016/bs.pmbts.2020.02.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Growing evidence suggests that imbalances in resident microbes (dysbiosis) can promote chronic inflammation, immune-subversion, and production of carcinogenic metabolites, thus leading to neoplasia. Yet, evidence to support a direct link of individual bacteria species to human sporadic cancer is still limited. This chapter focuses on several emerging bacterial toxins that have recently been characterized for their potential oncogenic properties toward human orodigestive cancer and the presence of which in human tissue samples has been documented. These include cytolethal distending toxins produced by various members of gamma and epsilon Proteobacteria, Dentilisin from mammalian oral Treponema, Pasteurella multocida toxin, two Fusobacterial toxins, FadA and Fap2, Bacteroides fragilis toxin, colibactin, cytotoxic necrotizing factors and α-hemolysin from Escherichia coli, and Salmonella enterica AvrA. It was clear that these bacterial toxins have biological activities to induce several hallmarks of cancer. Some toxins directly interact with DNA or chromosomes leading to their breakdowns, causing mutations and genome instability, and others modulate cell proliferation, replication and death and facilitate immune evasion and tumor invasion, prying specific oncogene and tumor suppressor pathways, such as p53 and β-catenin/Wnt. In addition, most bacterial toxins control tumor-promoting inflammation in complex and diverse mechanisms. Despite growing laboratory evidence to support oncogenic potential of selected bacterial toxins, we need more direct evidence from human studies and mechanistic data from physiologically relevant experimental animal models, which can reflect chronic infection in vivo, as well as take bacterial-bacterial interactions among microbiome into consideration.
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Affiliation(s)
| | - Adrian A Vasquez
- Department of Civil and Environmental Engineering, Wayne State University, Healthy Urban Waters, Detroit, MI, United States
| | - Carol J Miller
- Department of Civil and Environmental Engineering, Wayne State University, Healthy Urban Waters, Detroit, MI, United States
| | - Jun Sun
- Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Ikuko Kato
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI, United States; Department of Pathology, Wayne State University School of Medicine, Detroit, MI, United States.
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14
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Shenker BJ, Walker LM, Zekavat Z, Ojcius DM, Huang PR, Boesze-Battaglia K. Cytolethal distending toxin-induced release of interleukin-1β by human macrophages is dependent upon activation of glycogen synthase kinase 3β, spleen tyrosine kinase (Syk) and the noncanonical inflammasome. Cell Microbiol 2020; 22:e13194. [PMID: 32068949 DOI: 10.1111/cmi.13194] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 01/09/2020] [Accepted: 01/24/2020] [Indexed: 12/19/2022]
Abstract
Cytolethal distending toxins (Cdt) are a family of toxins produced by several human pathogens which infect mucocutaneous tissue and induce inflammatory disease. We have previously demonstrated that the Aggregatibacter actinomycetemcomitans Cdt induces a pro-inflammatory response from human macrophages which involves activation of the NLRP3 inflammasome. We now demonstrate that in addition to activating caspase-1 (canonical inflammasome), Cdt treatment leads to caspase-4 activation and involvement of the noncanonical inflammasome. Cdt-treated cells exhibit pyroptosis characterised by cleavage of gasdermin-D (GSDMD), release of HMGB1 at 24 hr and LDH at 48 hr. Inhibition of either the canonical (caspase-1) or noncanonical (caspase-4) inflammasome blocks both Cdt-induced release of IL-1β and induction of pyroptosis. Analysis of upstream events indicates that Cdt induces Syk phosphorylation (activation); furthermore, blockade of Syk expression and inhibition of pSyk activity inhibit both Cdt-induced cytokine release and pyroptosis. Finally, we demonstrate that increases in pSyk are dependent upon Cdt-induced activation of GSK3β. These studies advance our understanding of Cdt function and provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms such as A. actinomycetemcomitans.
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Affiliation(s)
- Bruce J Shenker
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA
| | - Lisa M Walker
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA
| | - Zeyed Zekavat
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA
| | - David M Ojcius
- Department of Biomedical Sciences, University of the Pacific Arthur A. Dugoni School of Dentistry, San Francisco, California, USA
| | - Pei-Rong Huang
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania, USA
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15
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Martin OC, Frisan T. Bacterial Genotoxin-Induced DNA Damage and Modulation of the Host Immune Microenvironment. Toxins (Basel) 2020; 12:E63. [PMID: 31973033 PMCID: PMC7076804 DOI: 10.3390/toxins12020063] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 01/14/2020] [Accepted: 01/18/2020] [Indexed: 01/10/2023] Open
Abstract
: Bacterial genotoxins (BTGX) induce DNA damage, which results in senescence or apoptosis of the target cells if not properly repaired. Three BTGXs have been identified: the cytolethal distending toxin (CDT) family produced by several Gram-negative bacteria, the typhoid toxin produced by several Salmonella enterica serovars, and colibactin, a peptide-polyketide, produced mainly by the phylogenetic group B2 Escherichia coli. The cellular responses induced by BTGXs resemble those of well-characterized carcinogenic agents, and several lines of evidence indicate that bacteria carrying genotoxin genes can contribute to tumor development under specific circumstances. Given their unusual mode of action, it is still enigmatic why these effectors have been acquired by microbes and what is their role in the context of the biology of the producing bacterium, since it is unlikely that their primary purpose is to induce/promote cancer in the mammalian host. In this review, we will discuss the possibility that the DNA damage induced by BTGX modulates the host immune response, acting as immunomodulator, leading to the establishment of a suitable niche for the producing bacterium. We will further highlight open questions that remain to be solved regarding the biology of this unusual family of bacterial toxins.
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Affiliation(s)
- Océane C.B. Martin
- Univ. Bordeaux, INSERM, UMR1053 Bordeaux Research in Translational Oncology, BaRITOn, 33320 Bordeaux, France;
| | - Teresa Frisan
- Department of Cell and Molecular Biology Karolinska Institutet, 17177 Stockholm, Sweden
- Umeå Center for Microbial Research (UCMR), Umeå University, 90187 Umeå, Sweden
- Department of Molecular Biology, Umeå University, 90187 Umeå, Sweden
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16
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The Cell-Cycle Regulatory Protein p21 CIP1/WAF1 Is Required for Cytolethal Distending Toxin (Cdt)-Induced Apoptosis. Pathogens 2020; 9:pathogens9010038. [PMID: 31906446 PMCID: PMC7168616 DOI: 10.3390/pathogens9010038] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/22/2019] [Accepted: 12/28/2019] [Indexed: 12/27/2022] Open
Abstract
The Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) induces lymphocytes to undergo cell-cycle arrest and apoptosis; toxicity is dependent upon the active Cdt subunit, CdtB. We now demonstrate that p21CIP1/WAF1 is critical to Cdt-induced apoptosis. Cdt induces increases in the levels of p21CIP1/WAF1 in lymphoid cell lines, Jurkat and MyLa, and in primary human lymphocytes. These increases were dependent upon CdtB’s ability to function as a phosphatidylinositol (PI) 3,4,5-triphosphate (PIP3) phosphatase. It is noteworthy that Cdt-induced increases in the levels of p21CIP1/WAF1 were accompanied by a significant decline in the levels of phosphorylated p21CIP1/WAF1. The significance of Cdt-induced p21CIP1/WAF1 increase was assessed by preventing these changes with a two-pronged approach; pre-incubation with the novel p21CIP1/WAF1 inhibitor, UC2288, and development of a p21CIP1/WAF1-deficient cell line (Jurkatp21−) using clustered regularly interspaced short palindromic repeats (CRISPR)/cas9 gene editing. UC2288 blocked toxin-induced increases in p21CIP1/WAF1, and JurkatWT cells treated with this inhibitor exhibited reduced susceptibility to Cdt-induced apoptosis. Likewise, Jurkatp21− cells failed to undergo toxin-induced apoptosis. The linkage between Cdt, p21CIP1/WAF1, and apoptosis was further established by demonstrating that Cdt-induced increases in levels of the pro-apoptotic proteins Bid, Bax, and Bak were dependent upon p21CIP1/WAF1 as these changes were not observed in Jurkatp21− cells. Finally, we determined that the p21CIP1/WAF1 increases were dependent upon toxin-induced increases in the level and activity of the chaperone heat shock protein (HSP) 90. We propose that p21CIP1/WAF1 plays a key pro-apoptotic role in mediating Cdt-induced toxicity.
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17
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Sun Z, Xiong C, Teh SW, Lim JCW, Kumar S, Thilakavathy K. Mechanisms of Oral Bacterial Virulence Factors in Pancreatic Cancer. Front Cell Infect Microbiol 2019; 9:412. [PMID: 31867287 PMCID: PMC6904357 DOI: 10.3389/fcimb.2019.00412] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 11/19/2019] [Indexed: 12/19/2022] Open
Abstract
Pancreatic cancer is a highly lethal disease, and most patients remain asymptomatic until the disease enters advanced stages. There is lack of knowledge in the pathogenesis, effective prevention and early diagnosis of pancreatic cancer. Recently, bacteria were found in pancreatic tissue that has been considered sterile before. The distribution of flora in pancreatic cancer tissue was reported to be different from normal pancreatic tissue. These abnormally distributed bacteria may be the risk factors for inducing pancreatic cancer. Therefore, studies on combined effect of multi-bacterial and multi-virulence factors may add to the knowledge of pancreatic cancer pathogenesis and aid in designing new preventive and therapeutic strategies. In this review, we outlined three oral bacteria associated with pancreatic cancer and their virulence factors linked with cancer.
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Affiliation(s)
- Zhong Sun
- Department of Biomedical Science, Universiti Putra Malaysia, Serdang, Malaysia
| | - ChengLong Xiong
- Department of Public Health Microbiology, School of Public Health, Fudan University, Shanghai, China
| | - Seoh Wei Teh
- Department of Medical Microbiology and Parasitology, Universiti Putra Malaysia, Serdang, Malaysia
| | - Jonathan Chee Woei Lim
- Pharmacotherapeutics Unit, Department of Medicine, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Suresh Kumar
- Department of Medical Microbiology and Parasitology, Universiti Putra Malaysia, Serdang, Malaysia.,Genetics and Regenerative Medicine Research Centre, Universiti Putra Malaysia, Serdang, Malaysia.,UPM-MAKNA Cancer Research Laboratory, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Malaysia
| | - Karuppiah Thilakavathy
- Department of Biomedical Science, Universiti Putra Malaysia, Serdang, Malaysia.,Genetics and Regenerative Medicine Research Centre, Universiti Putra Malaysia, Serdang, Malaysia
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18
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Cytolethal Distending Toxin Subunit B: A Review of Structure-Function Relationship. Toxins (Basel) 2019; 11:toxins11100595. [PMID: 31614800 PMCID: PMC6832162 DOI: 10.3390/toxins11100595] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 01/27/2023] Open
Abstract
The Cytolethal Distending Toxin (CDT) is a bacterial virulence factor produced by several Gram-negative pathogenic bacteria. These bacteria, found in distinct niches, cause diverse infectious diseases and produce CDTs differing in sequence and structure. CDTs have been involved in the pathogenicity of the associated bacteria by promoting persistent infection. At the host-cell level, CDTs cause cell distension, cell cycle block and DNA damage, eventually leading to cell death. All these effects are attributable to the catalytic CdtB subunit, but its exact mode of action is only beginning to be unraveled. Sequence and 3D structure analyses revealed similarities with better characterized proteins, such as nucleases or phosphatases, and it has been hypothesized that CdtB exerts a biochemical activity close to those enzymes. Here, we review the relationships that have been established between CdtB structure and function, particularly by mutation experiments on predicted key residues in different experimental systems. We discuss the relevance of these approaches and underline the importance of further study in the molecular mechanisms of CDT toxicity, particularly in the context of different pathological conditions.
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19
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Denmongkholchai S, Katare P, Choochuay S, Thanyasrisung P, Tsuruda K, Sugai M, Mongkolsuk S, Matangkasombut O. Genome-Wide Identification of Host Genes Required for Toxicity of Bacterial Cytolethal Distending Toxin in a Yeast Model. Front Microbiol 2019; 10:890. [PMID: 31080443 PMCID: PMC6497811 DOI: 10.3389/fmicb.2019.00890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/08/2019] [Indexed: 12/16/2022] Open
Abstract
Background Aggregatibacter actinomycetemcomitans, a periodontal pathogen, secretes a cytolethal distending toxin (AaCDT) that causes host cell cycle arrest and cell death. Although CDT could be an important virulence factor, it is unclear how it enters the nucleus to exert its cytotoxicity. Objective To investigate the mechanisms of AaCDT by genome-wide screening for host mutations that confer resistance to the catalytic subunit, AaCdtB, in a Saccharomyces cerevisiae model. Methods We transformed the yeast haploid deletion library, a collection of yeast mutants with single gene deletions of virtually all non-essential ORFs in the genome, with plasmids carrying galactose-inducible AaCdtB. Yeast mutants that showed resistance to AaCdtB were selected and rescreened by a spotting assay. AaCdtB expression was confirmed by western blot analysis; any mutants that showed no or weak expression of AaCdtB were omitted from the analysis. The lists of genes whose mutations confer resistance to AaCdtB were analyzed for Gene Ontology (GO) term enrichments. Localization of AaCdtB-EGFP was examined using fluorescent microscopy. Nuclear localization relative to EGFP control was calculated and compared to wild-type. Results Out of approximately 5,000 deletion mutants, we isolated 243 mutants that are resistant to AaCdtB. GO analyses indicated that genes associated with organic anion transport are significantly enriched (16 genes). Furthermore, several genes associated with the nucleus and endoplasmic reticulum (ER) were identified. Localization studies of AaCdtB, in mutants with the deletion of genes associated with the GO term organic anion transport, showed lower nuclear localization than wild-type. The results suggest that these genes may be required for AaCdtB translocation into the nucleus and its cytotoxicity. Conclusion The genome-wide screen in the yeast deletion library allowed us to identify a large number of host genes required for AaCdtB cytotoxicity. Further investigation could lead to more insights into the mechanisms of CdtB intoxication.
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Affiliation(s)
- Siriyod Denmongkholchai
- Interdepartmental Program in Medical Microbiology, Graduate School, Chulalongkorn University, Bangkok, Thailand.,Department of Microbiology and Research Unit on Oral Microbiology and Immunology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Prashant Katare
- Department of Microbiology and Research Unit on Oral Microbiology and Immunology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.,Graduate Program in Oral Biology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Sarocha Choochuay
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Panida Thanyasrisung
- Department of Microbiology and Research Unit on Oral Microbiology and Immunology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Keiko Tsuruda
- Department of Oral Epidemiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Motoyuki Sugai
- Department of Antimicrobial Resistance, Graduate School of Biomedical and Health Sciences, Project Research Center for Nosocomial Infectious Diseases (RCNID), Hiroshima University, Hiroshima, Japan.,Antimicrobial Resistance Research Center, National Institute of Infectious Diseases (NIID), Tokyo, Japan
| | - Skorn Mongkolsuk
- Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
| | - Oranart Matangkasombut
- Department of Microbiology and Research Unit on Oral Microbiology and Immunology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.,Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand
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20
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Pons BJ, Bezine E, Hanique M, Guillet V, Mourey L, Chicher J, Frisan T, Vignard J, Mirey G. Cell transfection of purified cytolethal distending toxin B subunits allows comparing their nuclease activity while plasmid degradation assay does not. PLoS One 2019; 14:e0214313. [PMID: 30921382 PMCID: PMC6438463 DOI: 10.1371/journal.pone.0214313] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 03/11/2019] [Indexed: 12/30/2022] Open
Abstract
The Cytolethal Distending Toxin (CDT) is produced by many pathogenic bacteria. CDT is known to induce genomic DNA damage to host eukaryotic cells through its catalytic subunit, CdtB. CdtB is structurally homologous to DNase I and has a nuclease activity, dependent on several key residues. Yet some differences between various CdtB subunit activities, and discrepancies between biochemical and cellular data, have been observed. To better characterise the role of CdtB in the induction of DNA damage, we affinity-purified wild-type and mutants of CdtB, issued from E. coli and H. ducreyi, under native and denaturing conditions. We then compared their nuclease activity by a classic in vitro assay using plasmid DNA, and two different eukaryotic assays–the first assay where host cells were transfected with a plasmid encoding CdtB, the second assay where host cells were directly transfected with purified CdtB. We show here that in vitro nuclease activities are difficult to quantify, whereas CdtB activities in host cells can be easily interpreted and confirmed the loss of function of the catalytic mutant. Our results highlight the importance of performing multiple assays while studying the effects of bacterial genotoxins, and indicate that the classic in vitro assay should be complemented with cellular assays.
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Affiliation(s)
- Benoît J. Pons
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, Toulouse, France
- Université Toulouse III–Paul Sabatier (UPS), Toulouse, France
| | - Elisabeth Bezine
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, Toulouse, France
- Institut National Polytechnique de Toulouse, Toulouse, France
| | - Mélissa Hanique
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, Toulouse, France
| | - Valérie Guillet
- Université Toulouse III–Paul Sabatier (UPS), Toulouse, France
- Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS), Toulouse, France
| | - Lionel Mourey
- Université Toulouse III–Paul Sabatier (UPS), Toulouse, France
- Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS), Toulouse, France
| | - Johana Chicher
- Plateforme protéomique Strasbourg Esplanade, Institut de Biologie Moléculaire et Cellulaire (IBMC), FRC1589 Strasbourg, France
| | - Teresa Frisan
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
| | - Julien Vignard
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, Toulouse, France
- * E-mail: (GM); (JV)
| | - Gladys Mirey
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, Toulouse, France
- Université Toulouse III–Paul Sabatier (UPS), Toulouse, France
- * E-mail: (GM); (JV)
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21
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Bertinat R, Westermeier F, Gatica R, Nualart F. Sodium tungstate: Is it a safe option for a chronic disease setting, such as diabetes? J Cell Physiol 2018; 234:51-60. [DOI: 10.1002/jcp.26913] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 06/13/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Romina Bertinat
- Centro de Microscopía Avanzada, CMA Bio‐Bio Facultad de Ciencias Biológicas, Universidad de Concepción Concepción Chile
| | - Francisco Westermeier
- Department of Health Studies Institute of Biomedical Science, FH JOANNEUM Gesellschaft mbH University of Applied Sciences Graz Austria
- Facultad de Ciencia, Universidad San Sebastián Santiago Chile
| | - Rodrigo Gatica
- Laboratorio de Patología Veterinaria Escuela de Veterinaria, Facultad de Ciencias, Universidad Mayor Santiago Chile
| | - Francisco Nualart
- Centro de Microscopía Avanzada, CMA Bio‐Bio Facultad de Ciencias Biológicas, Universidad de Concepción Concepción Chile
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22
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Boesze-Battaglia K, Walker LP, Dhingra A, Kandror K, Tang HY, Shenker BJ. Internalization of the Active Subunit of the Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Is Dependent upon Cellugyrin (Synaptogyrin 2), a Host Cell Non-Neuronal Paralog of the Synaptic Vesicle Protein, Synaptogyrin 1. Front Cell Infect Microbiol 2017; 7:469. [PMID: 29184850 PMCID: PMC5694546 DOI: 10.3389/fcimb.2017.00469] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/25/2017] [Indexed: 12/17/2022] Open
Abstract
The Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is a heterotrimeric AB2 toxin capable of inducing lymphocytes, and other cell types, to undergo cell cycle arrest and apoptosis. Exposure to Cdt results in binding to the cell surface followed by internalization and translocation of the active subunit, CdtB, to intracellular compartments. These events are dependent upon toxin binding to cholesterol in the context of lipid rich membrane microdomains often referred to as lipid rafts. We now demonstrate that, in addition to binding to the plasma membrane of lymphocytes, another early and critical event initiated by Cdt is the translocation of the host cell protein, cellugyrin (synaptogyrin-2) to the same cholesterol-rich microdomains. Furthermore, we demonstrate that cellugyrin is an intracellular binding partner for CdtB as demonstrated by immunoprecipitation. Using CRISPR/cas9 gene editing we established a Jurkat cell line deficient in cellugyrin expression (JurkatCg−); these cells were capable of binding Cdt, but unable to internalize CdtB. Furthermore, JurkatCg− cells were not susceptible to Cdt-induced toxicity; these cells failed to exhibit blockade of the PI-3K signaling pathway, cell cycle arrest or cell death. We propose that cellugyrin plays a critical role in the internalization and translocation of CdtB to critical intracellular target sites. These studies provide critical new insight into the mechanism by which Cdt, and in particular, CdtB is able to induce toxicity.
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Affiliation(s)
- Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Lisa P Walker
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Anuradha Dhingra
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Konstantin Kandror
- Department of Biochemistry, School of Medicine, Boston University, Boston, MA, United States
| | - Hsin-Yao Tang
- Wistar Proteomics and Metabolomics Core Facility, Wistar Institute, Philadelphia, PA, United States
| | - Bruce J Shenker
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
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23
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Ramachandran N, Ramlal S, Batra HV. Confirmed identification and toxin profiling of Campylobacter jejuni using a thermostabilized multiplex PCR formulation. APMIS 2017; 125:641-649. [PMID: 28574617 DOI: 10.1111/apm.12700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 02/27/2017] [Indexed: 11/28/2022]
Abstract
Cytolethal distending toxin (CDT) producing Campylobacter jejuni species are one of the leading causes of human gastroenteritis worldwide. The main intent of the study was to develop a multiplex PCR assay for the confirmed identification and toxin profiling of C. jejuni. The genes targeted were rpo B as genus specific, hip O for species; cdt A, cdt B, cdt C encoding respective subunit proteins of CDT with Internal Amplification Control (IAC). To enhance its application as a pre-mixed ready-to-use format, the master mix of developed mPCR was dried by lyophilization and stability was assessed. Thermostabilized reagents showed stability of 1.5 months at room-temperature and upto six months at 4 °C without any loss of functionality. The assay was evaluated on a number of presumptive Campylobacter isolates along with biochemical tests. Results obtained indicated the accurate identification of C. jejuni by developed mPCR format in contrast to misconception associated with biochemical assays. The assay was also tested on spiked samples for its real-time utility. Altogether, the room-temperature storable and ready-to- use mPCR format developed in this study could be preferred for rapid detection and confirmed identification of toxigenic strains of C. jejuni in place of conventional biochemical assays.
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Affiliation(s)
- Nitya Ramachandran
- Microbiology Division, Defence Food Research Laboratory, Mysore, Karnataka, India
| | - Shylaja Ramlal
- Microbiology Division, Defence Food Research Laboratory, Mysore, Karnataka, India
| | - Harsh Vardhan Batra
- Microbiology Division, Defence Food Research Laboratory, Mysore, Karnataka, India
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24
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El-Aouar Filho RA, Nicolas A, De Paula Castro TL, Deplanche M, De Carvalho Azevedo VA, Goossens PL, Taieb F, Lina G, Le Loir Y, Berkova N. Heterogeneous Family of Cyclomodulins: Smart Weapons That Allow Bacteria to Hijack the Eukaryotic Cell Cycle and Promote Infections. Front Cell Infect Microbiol 2017; 7:208. [PMID: 28589102 PMCID: PMC5440457 DOI: 10.3389/fcimb.2017.00208] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/09/2017] [Indexed: 12/13/2022] Open
Abstract
Some bacterial pathogens modulate signaling pathways of eukaryotic cells in order to subvert the host response for their own benefit, leading to successful colonization and invasion. Pathogenic bacteria produce multiple compounds that generate favorable conditions to their survival and growth during infection in eukaryotic hosts. Many bacterial toxins can alter the cell cycle progression of host cells, impairing essential cellular functions and impeding host cell division. This review summarizes current knowledge regarding cyclomodulins, a heterogeneous family of bacterial effectors that induce eukaryotic cell cycle alterations. We discuss the mechanisms of actions of cyclomodulins according to their biochemical properties, providing examples of various cyclomodulins such as cycle inhibiting factor, γ-glutamyltranspeptidase, cytolethal distending toxins, shiga toxin, subtilase toxin, anthrax toxin, cholera toxin, adenylate cyclase toxins, vacuolating cytotoxin, cytotoxic necrotizing factor, Panton-Valentine leukocidin, phenol soluble modulins, and mycolactone. Special attention is paid to the benefit provided by cyclomodulins to bacteria during colonization of the host.
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Affiliation(s)
- Rachid A El-Aouar Filho
- STLO, Agrocampus Ouest Rennes, Institut National de la Recherche AgronomiqueRennes, France.,Departamento de Biologia Geral, Laboratório de Genética Celular e Molecular (LGCM), Instituto de Ciências Biológicas, Universidade Federal de Minas GeraisBelo Horizonte, Brazil
| | - Aurélie Nicolas
- STLO, Agrocampus Ouest Rennes, Institut National de la Recherche AgronomiqueRennes, France
| | - Thiago L De Paula Castro
- Departamento de Biologia Geral, Laboratório de Genética Celular e Molecular (LGCM), Instituto de Ciências Biológicas, Universidade Federal de Minas GeraisBelo Horizonte, Brazil
| | - Martine Deplanche
- STLO, Agrocampus Ouest Rennes, Institut National de la Recherche AgronomiqueRennes, France
| | - Vasco A De Carvalho Azevedo
- Departamento de Biologia Geral, Laboratório de Genética Celular e Molecular (LGCM), Instituto de Ciências Biológicas, Universidade Federal de Minas GeraisBelo Horizonte, Brazil
| | - Pierre L Goossens
- HistoPathologie et Modèles Animaux/Pathogénie des Toxi-Infections Bactériennes, Institut PasteurParis, France
| | - Frédéric Taieb
- CHU Purpan USC INRA 1360-CPTP, U1043 Institut National de la Santé et de la Recherche Médicale, Pathogénie Moléculaire et Cellulaire des Infections à Escherichia coliToulouse, France
| | - Gerard Lina
- International Center for Infectiology ResearchLyon, France.,Centre National de la Recherche Scientifique, UMR5308, Institut National de la Santé et de la Recherche Médicale U1111, Ecole Normale Supérieure de Lyon, Université Lyon 1Lyon, France.,Département de Biologie, Institut des Agents Infectieux, Hospices Civils de LyonLyon, France
| | - Yves Le Loir
- STLO, Agrocampus Ouest Rennes, Institut National de la Recherche AgronomiqueRennes, France
| | - Nadia Berkova
- STLO, Agrocampus Ouest Rennes, Institut National de la Recherche AgronomiqueRennes, France
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25
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The mechanism of Jurkat cells apoptosis induced by Aggregatibacter actinomycetemcomitans cytolethal distending toxin. Apoptosis 2017; 22:841-851. [DOI: 10.1007/s10495-017-1357-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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26
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Scuron MD, Boesze-Battaglia K, Dlakić M, Shenker BJ. The Cytolethal Distending Toxin Contributes to Microbial Virulence and Disease Pathogenesis by Acting As a Tri-Perditious Toxin. Front Cell Infect Microbiol 2016; 6:168. [PMID: 27995094 PMCID: PMC5136569 DOI: 10.3389/fcimb.2016.00168] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/15/2016] [Indexed: 12/11/2022] Open
Abstract
This review summarizes the current status and recent advances in our understanding of the role that the cytolethal distending toxin (Cdt) plays as a virulence factor in promoting disease by toxin-producing pathogens. A major focus of this review is on the relationship between structure and function of the individual subunits that comprise the AB2 Cdt holotoxin. In particular, we concentrate on the molecular mechanisms that characterize this toxin and which account for the ability of Cdt to intoxicate multiple cell types by utilizing a ubiquitous binding partner on the cell membrane. Furthermore, we propose a paradigm shift for the molecular mode of action by which the active Cdt subunit, CdtB, is able to block a key signaling cascade and thereby lead to outcomes based upon programming and the role of the phosphatidylinositol 3-kinase (PI-3K) in a variety of cells. Based upon the collective Cdt literature, we now propose that Cdt is a unique and potent virulence factor capable of acting as a tri-perditious toxin that impairs host defenses by: (1) disrupting epithelial barriers; (2) suppressing acquired immunity; (3) promoting pro-inflammatory responses. Thus, Cdt plays a key role in facilitating the early stages of infection and the later stages of disease progression by contributing to persistence and impairing host elimination.
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Affiliation(s)
- Monika D Scuron
- Department of Pathology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, School of Dental Medicine, University of Pennsylvania Philadelphia, PA, USA
| | - Mensur Dlakić
- Department of Microbiology and Immunology, Montana State University Bozeman, MT, USA
| | - Bruce J Shenker
- Department of Pathology, School of Dental Medicine, University of Pennsylvania Philadelphia, PA, USA
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27
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Boesze-Battaglia K, Alexander D, Dlakić M, Shenker BJ. A Journey of Cytolethal Distending Toxins through Cell Membranes. Front Cell Infect Microbiol 2016; 6:81. [PMID: 27559534 PMCID: PMC4978709 DOI: 10.3389/fcimb.2016.00081] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 07/26/2016] [Indexed: 02/06/2023] Open
Abstract
The multifunctional role of lipids as structural components of membranes, signaling molecules, and metabolic substrates makes them an ideal partner for pathogens to hijack host cell processes for their own survival. The properties and composition of unique membrane micro-domains such as membrane rafts make these regions a natural target for pathogens as it affords them an opportunity to hijack cell signaling and intracellular trafficking pathways. Cytolethal distending toxins (Cdts), members of the AB2 family of toxins are comprised of three subunits, the active, CdtB unit, and the binding, CdtA-CdtC unit. Cdts are cyclomodulins leading to cell cycle arrest and apoptosis in a wide variety of cell types. Cdts from several species share a requirement for membrane rafts, and often cholesterol specifically for cell binding and CdtB mediated cytotoxicity. In this review we focus on how host–cell membrane bilayer organization contributes to the cell surface association, internalization, and action of bacteria derived cytolethal distending toxins (Cdts), with an emphasis on Aggregatibacter actinomycetemcomitans Cdt.
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Affiliation(s)
| | - Desiree Alexander
- Department of Biochemistry, SDM, University of Pennsylvania Philadelphia, PA, USA
| | - Mensur Dlakić
- Department of Microbiology and Immunology, Montana State University Bozeman, MT, USA
| | - Bruce J Shenker
- Department of Pathology, SDM, University of Pennsylvania Philadelphia, PA, USA
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28
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Impact of CDT Toxin on Human Diseases. Toxins (Basel) 2016; 8:toxins8070220. [PMID: 27429000 PMCID: PMC4963852 DOI: 10.3390/toxins8070220] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 07/01/2016] [Accepted: 07/06/2016] [Indexed: 12/18/2022] Open
Abstract
Cytolethal distending toxin (CDT) is found in Gram-negative bacteria, especially in certain Proteobacteria such as the Pasteurellaceae family, including Haemophilus ducreyi and Aggregatibacter (Actinobacillus) actinomycetemcomitans, in the Enterobacteriaceae family and the Campylobacterales order, including the Campylobacter and Helicobacter species. In vitro and in vivo studies have clearly shown that this toxin has a strong effect on cellular physiology (inflammation, immune response modulation, tissue damage). Some works even suggest a potential involvement of CDT in cancers. In this review, we will discuss these different aspects.
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29
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Obradović D, Gašperšič R, Caserman S, Leonardi A, Jamnik M, Podlesek Z, Seme K, Anderluh G, Križaj I, Maček P, Butala M. A Cytolethal Distending Toxin Variant from Aggregatibacter actinomycetemcomitans with an Aberrant CdtB That Lacks the Conserved Catalytic Histidine 160. PLoS One 2016; 11:e0159231. [PMID: 27414641 PMCID: PMC4945079 DOI: 10.1371/journal.pone.0159231] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/29/2016] [Indexed: 12/19/2022] Open
Abstract
The periodontopathogen Aggregatibacter actinomycetemcomitans synthesizes several virulence factors, including cytolethal distending toxin (CDT). The active CDT holoenzyme is an AB-type tripartite genotoxin that affects eukaryotic cells. Subunits CdtA and CdtC (B-components) allow binding and intracellular translocation of the active CdtB (A-component), which elicits nuclear DNA damage. Different strains of A. actinomycetemcomitans have diverse virulence genotypes, which results in varied pathogenic potential and disease progression. Here, we identified an A. actinomycetemcomitans strain isolated from two patients with advance chronic periodontitis that has a regular cdtABC operon, which, however, codes for a unique, shorter, variant of the CdtB subunit. We describe the characteristics of this CdtBΔ116–188, which lacks the intact nuclear localisation signal and the catalytic histidine 160. We show that the A. actinomycetemcomitans DO15 isolate secretes CdtBΔ116–188, and that this subunit cannot form a holotoxin and is also not genotoxic if expressed ectopically in HeLa cells. Furthermore, the A. actinomycetemcomitans DO15 isolate is not toxic, nor does it induce cellular distention upon infection of co-cultivated HeLa cells. Biological significance of this deletion in the cdtB remains to be explained.
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Affiliation(s)
- Davor Obradović
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Rok Gašperšič
- Department of Oral Medicine and Periodontology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Simon Caserman
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Adrijana Leonardi
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Maja Jamnik
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Zdravko Podlesek
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | - Katja Seme
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Gregor Anderluh
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
| | - Igor Križaj
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana, Slovenia
- Department of Chemistry and Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
| | - Peter Maček
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- * E-mail: (PM); (MB)
| | - Matej Butala
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
- * E-mail: (PM); (MB)
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30
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Taieb F, Petit C, Nougayrède JP, Oswald E. The Enterobacterial Genotoxins: Cytolethal Distending Toxin and Colibactin. EcoSal Plus 2016; 7. [PMID: 27419387 DOI: 10.1128/ecosalplus.esp-0008-2016] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Indexed: 06/06/2023]
Abstract
While the DNA damage induced by ionizing radiation and by many chemical compounds and drugs is well characterized, the genotoxic insults inflicted by bacteria are only scarcely documented. However, accumulating evidence indicates that we are exposed to bacterial genotoxins. The prototypes of such bacterial genotoxins are the Cytolethal Distending Toxins (CDTs) produced by Escherichia coli and Salmonella enterica serovar Typhi. CDTs display the DNase structure fold and activity, and induce DNA strand breaks in the intoxicated host cell nuclei. E. coli and certain other Enterobacteriaceae species synthesize another genotoxin, colibactin. Colibactin is a secondary metabolite, a hybrid polyketide/nonribosomal peptide compound synthesized by a complex biosynthetic machinery. In this review, we summarize the current knowledge on CDT and colibactin produced by E. coli and/or Salmonella Typhi. We describe their prevalence, genetic determinants, modes of action, and impact in infectious diseases or gut colonization, and discuss the possible involvement of these genotoxigenic bacteria in cancer.
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Affiliation(s)
- Frederic Taieb
- Institut de Recherche en Santé Digestive (IRSD), INRA UMR1416, INSERM U1220, Université de Toulouse, CHU Purpan, Toulouse, FRANCE
| | - Claude Petit
- Institut de Recherche en Santé Digestive (IRSD), INRA UMR1416, INSERM U1220, Université de Toulouse, CHU Purpan, Toulouse, FRANCE
| | - Jean-Philippe Nougayrède
- Institut de Recherche en Santé Digestive (IRSD), INRA UMR1416, INSERM U1220, Université de Toulouse, CHU Purpan, Toulouse, FRANCE
| | - Eric Oswald
- Institut de Recherche en Santé Digestive (IRSD), INRA UMR1416, INSERM U1220, Université de Toulouse, CHU Purpan, Toulouse, FRANCE
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31
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Miller R, Wiedmann M. Dynamic Duo-The Salmonella Cytolethal Distending Toxin Combines ADP-Ribosyltransferase and Nuclease Activities in a Novel Form of the Cytolethal Distending Toxin. Toxins (Basel) 2016; 8:E121. [PMID: 27120620 PMCID: PMC4885037 DOI: 10.3390/toxins8050121] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 03/30/2016] [Accepted: 04/15/2016] [Indexed: 01/02/2023] Open
Abstract
The cytolethal distending toxin (CDT) is a well characterized bacterial genotoxin encoded by several Gram-negative bacteria, including Salmonella enterica (S. enterica). The CDT produced by Salmonella (S-CDT) differs from the CDT produced by other bacteria, as it utilizes subunits with homology to the pertussis and subtilase toxins, in place of the traditional CdtA and CdtC subunits. Previously, S-CDT was thought to be a unique virulence factor of S. enterica subspecies enterica serotype Typhi, lending to its classification as the "typhoid toxin." Recently, this important virulence factor has been identified and characterized in multiple nontyphoidal Salmonella (NTS) serotypes as well. The significance of S-CDT in salmonellosis with regards to the: (i) distribution of S-CDT encoding genes among NTS serotypes, (ii) contributions to pathogenicity, (iii) regulation of S-CDT expression, and (iv) the public health implication of S-CDT as it relates to disease severity, are reviewed here.
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Affiliation(s)
- Rachel Miller
- Department of Food Science, Cornell University, Ithaca, NY 14850 USA.
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, NY 14850 USA.
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32
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Kawamoto D, Ando-Suguimoto ES, Bueno-Silva B, DiRienzo JM, Mayer MPA. Alteration of Homeostasis in Pre-osteoclasts Induced by Aggregatibacter actinomycetemcomitans CDT. Front Cell Infect Microbiol 2016; 6:33. [PMID: 27064424 PMCID: PMC4815040 DOI: 10.3389/fcimb.2016.00033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 03/07/2016] [Indexed: 01/28/2023] Open
Abstract
The dysbiotic microbiota associated with aggressive periodontitis includes Aggregatibacter actinomycetemcomitans, the only oral species known to produce a cytolethal distending toxin (AaCDT). Give that CDT alters the cytokine profile in monocytic cells, we aimed to test the hypothesis that CDT plays a role in bone homeostasis by affecting the differentiation of precursor cells into osteoclasts. Recombinant AaCDT was added to murine bone marrow monocytes (BMMC) in the presence or absence of RANKL and the cell viability and cytokine profile of osteoclast precursor cells were determined. Multinucleated TRAP(+) cell numbers, and relative transcription of genes related to osteoclastogenesis were also evaluated. The addition of AaCDT did not lead to loss in cell viability but promoted an increase in the average number of TRAP(+) cells with 1-2 nuclei in the absence or presence of RANKL (Tukey, p < 0.05). This increase was also observed for TRAP(+) cells with ≥3nuclei, although this difference was not significant. Levels of TGF-β, TNF-α, and IL-6, in the supernatant fraction of cells, were higher when in AaCDT exposed cells, whereas levels of IL-1β and IL-10 were lower than controls under the same conditions. After interaction with AaCDT, transcription of the rank (encoding the receptor RANK), nfatc1 (transcription factor), and ctpK (encoding cathepsin K) genes was downregulated in pre-osteoclastic cells. The data indicated that despite the presence of RANKL and M-CSF, AaCDT may inhibit osteoclast differentiation by altering cytokine profiles and repressing transcription of genes involved in osteoclastogenesis. Therefore, the CDT may impair host defense mechanisms in periodontitis.
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Affiliation(s)
- Dione Kawamoto
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo São Paulo, Brazil
| | - Ellen S Ando-Suguimoto
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo São Paulo, Brazil
| | - Bruno Bueno-Silva
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo São Paulo, Brazil
| | - Joseph M DiRienzo
- Department of Microbiology, School of Dental Medicine, University of Pennsylvania PA, USA
| | - Marcia P A Mayer
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo São Paulo, Brazil
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33
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Graillot V, Dormoy I, Dupuy J, Shay JW, Huc L, Mirey G, Vignard J. Genotoxicity of Cytolethal Distending Toxin (CDT) on Isogenic Human Colorectal Cell Lines: Potential Promoting Effects for Colorectal Carcinogenesis. Front Cell Infect Microbiol 2016; 6:34. [PMID: 27047802 PMCID: PMC4803749 DOI: 10.3389/fcimb.2016.00034] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/07/2016] [Indexed: 02/06/2023] Open
Abstract
The composition of the human microbiota influences tumorigenesis, notably in colorectal cancer (CRC). Pathogenic Escherichia coli possesses a variety of virulent factors, among them the Cytolethal Distending Toxin (CDT). CDT displays dual DNase and phosphatase activities and induces DNA double strand breaks, cell cycle arrest and apoptosis in a broad range of mammalian cells. As CDT could promote malignant transformation, we investigated the cellular outcomes induced by acute and chronic exposures to E. coli CDT in normal human colon epithelial cells (HCECs). Moreover, we conducted a comparative study between isogenic derivatives cell lines of the normal HCECs in order to mimic the mutation of three major genes found in CRC genetic models: APC, KRAS, and TP53. Our results demonstrate that APC and p53 deficient cells showed impaired DNA damage response after CDT exposure, whereas HCECs expressing oncogenic KRASV12 were more resistant to CDT. Compared to normal HCECs, the precancerous derivatives exhibit hallmarks of malignant transformation after a chronic exposure to CDT. HCECs defective in APC and p53 showed enhanced anchorage independent growth and genetic instability, assessed by the micronucleus formation assay. In contrast, the ability to grow independently of anchorage was not impacted by CDT chronic exposure in KRASV12 HCECs, but micronucleus formation is dramatically increased. Thus, CDT does not initiate CRC by itself, but may have promoting effects in premalignant HCECs, involving different mechanisms in function of the genetic alterations associated to CRC.
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Affiliation(s)
- Vanessa Graillot
- Institut National de la Recherche Agronomique UMR 1331, TOXALIM (Research Center in Food Toxicology), Université de Toulouse, INRA, INP-ENVT, INP-EI-Purpan, Université de Toulouse III Paul Sabatier Toulouse, France
| | - Inge Dormoy
- Institut National de la Recherche Agronomique UMR 1331, TOXALIM (Research Center in Food Toxicology), Université de Toulouse, INRA, INP-ENVT, INP-EI-Purpan, Université de Toulouse III Paul Sabatier Toulouse, France
| | - Jacques Dupuy
- Institut National de la Recherche Agronomique UMR 1331, TOXALIM (Research Center in Food Toxicology), Université de Toulouse, INRA, INP-ENVT, INP-EI-Purpan, Université de Toulouse III Paul Sabatier Toulouse, France
| | - Jerry W Shay
- Department of Cell Biology, The University of Texas Southwestern Medical CenterDallas, TX, USA; Center for Excellence in Genomics Medicine Research, King Abdulaziz UniversityJeddah, Saudi Arabia
| | - Laurence Huc
- Institut National de la Recherche Agronomique UMR 1331, TOXALIM (Research Center in Food Toxicology), Université de Toulouse, INRA, INP-ENVT, INP-EI-Purpan, Université de Toulouse III Paul Sabatier Toulouse, France
| | - Gladys Mirey
- Institut National de la Recherche Agronomique UMR 1331, TOXALIM (Research Center in Food Toxicology), Université de Toulouse, INRA, INP-ENVT, INP-EI-Purpan, Université de Toulouse III Paul Sabatier Toulouse, France
| | - Julien Vignard
- Institut National de la Recherche Agronomique UMR 1331, TOXALIM (Research Center in Food Toxicology), Université de Toulouse, INRA, INP-ENVT, INP-EI-Purpan, Université de Toulouse III Paul Sabatier Toulouse, France
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Lai CK, Chen YA, Lin CJ, Lin HJ, Kao MC, Huang MZ, Lin YH, Chiang-Ni C, Chen CJ, Lo UG, Lin LC, Lin H, Hsieh JT, Lai CH. Molecular Mechanisms and Potential Clinical Applications of Campylobacter jejuni Cytolethal Distending Toxin. Front Cell Infect Microbiol 2016; 6:9. [PMID: 26904508 PMCID: PMC4746238 DOI: 10.3389/fcimb.2016.00009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/18/2016] [Indexed: 12/12/2022] Open
Abstract
Cytolethal distending toxin (CDT), a genotoxin produced by Campylobacter jejuni, is composed of three subunits: CdtA, CdtB, and CdtC. CdtB is a DNase that causes DNA double-strand breaks (DSB) in the nucleus resulting in cell cycle arrest at the G2/M stage and apoptosis. CdtA and CdtC bind to cholesterol-rich microdomains on the cytoplasmic membrane, a process required for the delivery of CdtB to cells. Although a unique motif associated with cholesterol-binding activity has been identified in other pathogens, the mechanism underlying the interaction between the CdtA and CdtC subunits and membrane cholesterol remains unclear. Also, the processes of cell uptake and delivery of CdtB in host cells and the translocation of CdtB into the nucleus are only partially understood. In this review, we focus on the underlying relationship among CDT, membrane cholesterol, and the intracellular trafficking pathway as a unique mechanism for C. jejuni-induced pathogenesis. Moreover, we discuss the clinical aspects of a possible therapeutic application of CDT in cancer therapy. Understanding the molecular mechanism of CDT-host interactions may provide insights into novel strategies to control C. jejuni infection and the development of potential clinical applications of CDT.
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Affiliation(s)
- Cheng-Kuo Lai
- Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung UniversityTaoyuan, Taiwan; Department of Urology, University of Texas Southwestern Medical CenterDallas, TX, USA
| | - Yu-An Chen
- School of Medicine, Graduate Institute of Basic Medical Science, China Medical University Taichung, Taiwan
| | - Chun-Jung Lin
- Department of Urology, University of Texas Southwestern Medical CenterDallas, TX, USA; School of Medicine, Graduate Institute of Basic Medical Science, China Medical UniversityTaichung, Taiwan
| | - Hwai-Jeng Lin
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical UniversityNew Taipei, Taiwan; Division of Gastroenterology and Hepatology, Department of Internal Medicine, Shuang-Ho HospitalNew Taipei, Taiwan
| | - Min-Chuan Kao
- Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University Taoyuan, Taiwan
| | - Mei-Zi Huang
- Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung UniversityTaoyuan, Taiwan; School of Medicine, Graduate Institute of Basic Medical Science, China Medical UniversityTaichung, Taiwan
| | - Yu-Hsin Lin
- Department of Urology, University of Texas Southwestern Medical CenterDallas, TX, USA; Department of Biological Science and Technology, China Medical UniversityTaichung, Taiwan
| | - Chuan Chiang-Ni
- Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University Taoyuan, Taiwan
| | - Chih-Jung Chen
- Department of Pediatrics, Molecular Infectious Disease Research Center, Chang Gung Children's Hospital and Chang Gung Memorial Hospital Taoyuan, Taiwan
| | - U-Ging Lo
- Department of Urology, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Li-Chiung Lin
- Department of Urology, University of Texas Southwestern Medical CenterDallas, TX, USA; Department of Life Sciences, National Chung Hsing UniversityTaichung, Taiwan
| | - Ho Lin
- Department of Life Sciences, National Chung Hsing University Taichung, Taiwan
| | - Jer-Tsong Hsieh
- Department of Urology, University of Texas Southwestern Medical CenterDallas, TX, USA; Graduate Institute of Cancer Biology, China Medical UniversityTaichung, Taiwan
| | - Chih-Ho Lai
- Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung UniversityTaoyuan, Taiwan; School of Medicine, Graduate Institute of Basic Medical Science, China Medical UniversityTaichung, Taiwan; Department of Pediatrics, Molecular Infectious Disease Research Center, Chang Gung Children's Hospital and Chang Gung Memorial HospitalTaoyuan, Taiwan; Department of Nursing, Asia UniversityTaichung, Taiwan
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35
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Dixon SD, Huynh MM, Tamilselvam B, Spiegelman LM, Son SB, Eshraghi A, Blanke SR, Bradley KA. Distinct Roles for CdtA and CdtC during Intoxication by Cytolethal Distending Toxins. PLoS One 2015; 10:e0143977. [PMID: 26618479 PMCID: PMC4664275 DOI: 10.1371/journal.pone.0143977] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 11/11/2015] [Indexed: 12/29/2022] Open
Abstract
Cytolethal distending toxins (CDTs) are heterotrimeric protein exotoxins produced by a diverse array of Gram-negative pathogens. The enzymatic subunit, CdtB, possesses DNase and phosphatidylinositol 3-4-5 trisphosphate phosphatase activities that induce host cell cycle arrest, cellular distension and apoptosis. To exert cyclomodulatory and cytotoxic effects CDTs must be taken up from the host cell surface and transported intracellularly in a manner that ultimately results in localization of CdtB to the nucleus. However, the molecular details and mechanism by which CDTs bind to host cells and exploit existing uptake and transport pathways to gain access to the nucleus are poorly understood. Here, we report that CdtA and CdtC subunits of CDTs derived from Haemophilus ducreyi (Hd-CDT) and enteropathogenic E. coli (Ec-CDT) are independently sufficient to support intoxication by their respective CdtB subunits. CdtA supported CdtB-mediated killing of T-cells and epithelial cells that was nearly as efficient as that observed with holotoxin. In contrast, the efficiency by which CdtC supported intoxication was dependent on the source of the toxin as well as the target cell type. Further, CdtC was found to alter the subcellular trafficking of Ec-CDT as determined by sensitivity to EGA, an inhibitor of endosomal trafficking, colocalization with markers of early and late endosomes, and the kinetics of DNA damage response. Finally, host cellular cholesterol was found to influence sensitivity to intoxication mediated by Ec-CdtA, revealing a role for cholesterol or cholesterol-rich membrane domains in intoxication mediated by this subunit. In summary, data presented here support a model in which CdtA and CdtC each bind distinct receptors on host cell surfaces that direct alternate intracellular uptake and/or trafficking pathways.
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Affiliation(s)
- Shandee D. Dixon
- Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Melanie M. Huynh
- Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Batcha Tamilselvam
- Department of Microbiology, Institute for Genomic Biology, University of Illinois Urbana, Urbana, Illinois, United States of America
| | - Lindsey M. Spiegelman
- Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Sophia B. Son
- Department of Microbiology, Institute for Genomic Biology, University of Illinois Urbana, Urbana, Illinois, United States of America
| | - Aria Eshraghi
- Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Steven R. Blanke
- Department of Microbiology, Institute for Genomic Biology, University of Illinois Urbana, Urbana, Illinois, United States of America
| | - Kenneth A. Bradley
- Department of Microbiology, Immunology, and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
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Shenker BJ, Walker LP, Zekavat A, Boesze-Battaglia K. Lymphoid susceptibility to the Aggregatibacter actinomycetemcomitans cytolethal distending toxin is dependent upon baseline levels of the signaling lipid, phosphatidylinositol-3,4,5-triphosphate. Mol Oral Microbiol 2015; 31:33-42. [PMID: 26299277 DOI: 10.1111/omi.12127] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2015] [Indexed: 01/31/2023]
Abstract
The Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) induces G2 arrest and apoptosis in lymphocytes and other cell types. We have shown that the active subunit, CdtB, exhibits phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase activity and depletes lymphoid cells of PIP3. Hence we propose that Cdt toxicity results from depletion of this signaling lipid and perturbation of phosphatidylinositol-3-kinase (PI-3K)/PIP3/Akt signaling. We have now focused on the relationship between cell susceptibility to CdtB and differences in the status of baseline PIP3 levels. Our studies demonstrate that the baseline level of PIP3, and likely the dependence of cells on steady-state activity of the PI-3K signaling pathway for growth and survival, influence cell susceptibility to the toxic effects of Cdt. Jurkat cells with known defects in both PIP3 degradative enzymes, PTEN and SHIP1, not only contain high baseline levels of PIP3, pAkt, and pGSK3β, but also exhibit high sensitivity to Cdt. In contrast, HUT78 cells, with no known defects in this pathway, contain low levels of PIP3, pAkt, and pGSK3β and likely minimal dependence on the PI-3K signaling pathway for growth and survival, and exhibit reduced susceptibility to Cdt. These differences in susceptibility to Cdt cannot be explained by differential toxin binding or internalization of the active subunit. Indeed, we now demonstrate that Jurkat and HUT78 cells bind toxin at comparable levels and internalize relatively equal amounts of CdtB. The relevance of these observations to the mode of action of Cdt and its potential role as a virulence factor is discussed.
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Affiliation(s)
- B J Shenker
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - L P Walker
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - A Zekavat
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - K Boesze-Battaglia
- Department of Biochemistry, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
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Shenker BJ, Boesze-Battaglia K, Scuron MD, Walker LP, Zekavat A, Dlakić M. The toxicity of the Aggregatibacter actinomycetemcomitans cytolethal distending toxin correlates with its phosphatidylinositol-3,4,5-triphosphate phosphatase activity. Cell Microbiol 2015; 18:223-43. [PMID: 26247396 DOI: 10.1111/cmi.12497] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/22/2015] [Accepted: 07/26/2015] [Indexed: 12/22/2022]
Abstract
The Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) induces G2 arrest and apoptosis in lymphocytes and other cell types. We have shown that the active subunit, CdtB, exhibits phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase activity, leading us to propose that Cdt toxicity is the result of PIP3 depletion and perturbation of phosphatidylinositol-3-kinase (PI-3K)/PIP3/Akt signalling. To further explore this relationship, we have focused our analysis on identifying residues that comprise the catalytic pocket and are critical to substrate binding rather than catalysis. In this context, we have generated several CdtB mutants and demonstrate that, in each instance, the ability of the toxin to induce cell cycle arrest correlates with retention of phosphatase activity. We have also assessed the effect of Cdt on downstream components of the PI-3K signalling pathway. In addition to depletion of intracellular concentrations of PIP3, toxin-treated lymphocytes exhibit decreases in pAkt and pGSK3β. Further analysis indicates that toxin-treated cells exhibit a concomitant loss in Akt activity and increase in GSK3β kinase activity consistent with observed changes in their phosphorylation status. We demonstrate that cell susceptibility to Cdt is dependent upon dephosphorylation and concomitant activation of GSK3β. Finally, we demonstrate that, in addition to lymphocytes, HeLa cells exposed to a CdtB mutant that retains phosphatase activity and not DNase activity undergo G2 arrest in the absence of H2AX phosphorylation. Our results provide further insight into the mode of action by which Cdt may function as an immunotoxin and induce cell cycle arrest in target cells such as lymphocytes.
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Affiliation(s)
- Bruce J Shenker
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Kathleen Boesze-Battaglia
- Department of Biochemistry, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Monika Damek Scuron
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Lisa P Walker
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Ali Zekavat
- Department of Pathology, University of Pennsylvania School of Dental Medicine, Philadelphia, PA, USA
| | - Mensur Dlakić
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT, USA
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Bacterial Genotoxins: Merging the DNA Damage Response into Infection Biology. Biomolecules 2015; 5:1762-82. [PMID: 26270677 PMCID: PMC4598774 DOI: 10.3390/biom5031762] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 02/07/2023] Open
Abstract
Bacterial genotoxins are unique among bacterial toxins as their molecular target is DNA. The consequence of intoxication or infection is induction of DNA breaks that, if not properly repaired, results in irreversible cell cycle arrest (senescence) or death of the target cells. At present, only three bacterial genotoxins have been identified. Two are protein toxins: the cytolethal distending toxin (CDT) family produced by a number of Gram-negative bacteria and the typhoid toxin produced by Salmonella enterica serovar Typhi. The third member, colibactin, is a peptide-polyketide genotoxin, produced by strains belonging to the phylogenetic group B2 of Escherichia coli. This review will present the cellular effects of acute and chronic intoxication or infection with the genotoxins-producing bacteria. The carcinogenic properties and the role of these effectors in the context of the host-microbe interaction will be discussed. We will further highlight the open questions that remain to be solved regarding the biology of this unusual family of bacterial toxins.
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The Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Active Subunit CdtB Contains a Cholesterol Recognition Sequence Required for Toxin Binding and Subunit Internalization. Infect Immun 2015. [PMID: 26216427 DOI: 10.1128/iai.00788-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Induction of cell cycle arrest in lymphocytes following exposure to the Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is dependent upon the integrity of lipid membrane microdomains. Moreover, we have previously demonstrated that the association of Cdt with target cells involves the CdtC subunit which binds to cholesterol via a cholesterol recognition amino acid consensus sequence (CRAC site). In this study, we demonstrate that the active Cdt subunit, CdtB, also is capable of binding to large unilamellar vesicles (LUVs) containing cholesterol. Furthermore, CdtB binding to cholesterol involves a similar CRAC site as that demonstrated for CdtC. Mutation of the CRAC site reduces binding to model membranes as well as toxin binding and CdtB internalization in both Jurkat cells and human macrophages. A concomitant reduction in Cdt-induced toxicity was also noted, indicated by reduced cell cycle arrest and apoptosis in Jurkat cells and a reduction in the proinflammatory response in macrophages (interleukin 1β [IL-1β] and tumor necrosis factor alpha [TNF-α] release). Collectively, these observations indicate that membrane cholesterol serves as an essential ligand for both CdtC and CdtB and, further, that this binding is necessary for both internalization of CdtB and subsequent molecular events leading to intoxication of cells.
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Aggregatibacter actinomycetemcomitans cytolethal distending toxin activates the NLRP3 inflammasome in human macrophages, leading to the release of proinflammatory cytokines. Infect Immun 2015; 83:1487-96. [PMID: 25644004 DOI: 10.1128/iai.03132-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The cytolethal distending toxin (Cdt) is produced from a number of bacteria capable of causing infection and inflammatory disease. Our previous studies with Actinobacillus actinomycetemcomitans Cdt demonstrate not only that the active toxin subunit functions as a phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase but also that macrophages exposed to the toxin were stimulated to produce proinflammatory cytokines. We now demonstrate that the Cdt-induced proinflammatory response involves the activation of the NLRP3 inflammasome. Specific inhibitors and short hairpin RNA (shRNA) were employed to demonstrate requirements for NLRP3 and ASC as well as caspase-1. Furthermore, Cdt-mediated inflammasome activation is dependent upon upstream signals, including reactive oxygen species (ROS) generation and Cdt-induced increases in extracellular ATP levels. Increases in extracellular ATP levels contribute to the activation of the P2X7 purinergic receptor, leading to K+ efflux. The relationship between the abilities of the active toxin subunit CdtB to function as a lipid phosphatase, activate the NLRP3 inflammasome, and induce a proinflammatory cytokine response is discussed. These studies provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms such as Aggregatibacter actinomycetemcomitans.
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Şahin B, Fife J, Parmar MB, Valencia-Serna J, Gul-Uludağ H, Jiang X, Weinfeld M, Lavasanifar A, Uludağ H. siRNA therapy in cutaneous T-cell lymphoma cells using polymeric carriers. Biomaterials 2014; 35:9382-94. [DOI: 10.1016/j.biomaterials.2014.07.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 07/21/2014] [Indexed: 12/16/2022]
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Abstract
Some of the most potent toxins produced by plants and bacteria are members of a large family known as the AB toxins. AB toxins are generally characterized by a heterogenous complex consisting of two protein chains arranged in various monomeric or polymeric configurations. The newest class within this superfamily is the cytolethal distending toxin (Cdt). The Cdt is represented by a subfamily of toxins produced by a group of taxonomically distinct Gram negative bacteria. Members of this subfamily have a related AB-type chain or subunit configuration and properties distinctive to the AB paradigm. In this review, the unique structural and cytotoxic properties of the Cdt subfamily, target cell specificities, intoxication pathway, modes of action, and relationship to the AB toxin superfamily are compared and contrasted.
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Mezal EH, Bae D, Khan AA. Detection and functionality of the CdtB, PltA, and PltB from Salmonella enterica serovar Javiana. Pathog Dis 2014; 72:95-103. [PMID: 24891290 DOI: 10.1111/2049-632x.12191] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 05/23/2014] [Accepted: 05/23/2014] [Indexed: 11/27/2022] Open
Abstract
Salmonella infection is one of the major foodborne illnesses in the United States. Several Gram-negative bacterial pathogens, including Salmonella Typhi, produce cytolethal distending toxin (CDT), which arrests growth, induces apoptosis of infected host cells and extends persistence of pathogenic bacteria in the host. The aim of this study was to characterize the functionality of CDT (cdtB, pltA and pltB) from nontyphoidal Salmonella isolates. Fifty Salmonella enterica serovar Javiana isolates from food, environmental, and clinical samples were screened for cdtB, pltA, and pltB genes by PCR, and all were positive for all three genes. Nucleotide sequence analysis of all amplified PCR products showed 100% identity to S. Typhi cdtB. To understand the roles of CdtB, PltA, and PltB in S. Javiana, cdtB, pltA, and pltB deletion mutants were constructed using a lambda Red-based recombination system. In vitro-cultured HeLa cell lines were infected with a wild-type strain and its isogenic ∆cdtB, ∆pltA, and ∆pltB to determine whether the strains of S. Javiana are responsible for invasion and cytolethal distending intoxication, including cell cycle arrest, cytoplasmic distension, and nuclear enlargement of host target cells. The results showed that HeLa cells infected with S. Javiana wild type were arrested in G2 /M and had distended cytoplasm and nuclei that were larger than those infected with S. Javiana ∆cdtB and ∆pltA strains. The S. Javiana ∆pltB strain retained the ability to induce cytoplasmic distension and cell cycle arrest, whereas the complemented ∆cdtB and ∆pltA S. Javiana strains showed activity like the wild-type strains. CdtB and pltA from S. Javiana had apparent effects on the distension of both cytoplasm and nucleus as well as cell cycle arrest of HeLa cell lines after 72 h of infection. Our data show a significant difference between the wild-type cdtB strain and its isogenic ∆cdtB for invasion of the cell lines. Therefore, CdtB produced from S. Javiana strains may play an important role in pathogenesis in host cells.
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Affiliation(s)
- Ezat H Mezal
- Division of Microbiology, National Center for Toxicological Research, U. S. Food and Drug Administration, Jefferson, AR, USA; University of Arkansas at Little Rock, Little Rock, AR, USA; University of Thi-Qar, Thi-Qar, Iraq
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Bezine E, Vignard J, Mirey G. The cytolethal distending toxin effects on Mammalian cells: a DNA damage perspective. Cells 2014; 3:592-615. [PMID: 24921185 PMCID: PMC4092857 DOI: 10.3390/cells3020592] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 05/28/2014] [Accepted: 05/28/2014] [Indexed: 12/27/2022] Open
Abstract
The cytolethal distending toxin (CDT) is produced by many pathogenic Gram-negative bacteria and is considered as a virulence factor. In human cells, CDT exposure leads to a unique cytotoxicity associated with a characteristic cell distension and induces a cell cycle arrest dependent on the DNA damage response (DDR) triggered by DNA double-strand breaks (DSBs). CDT has thus been classified as a cyclomodulin and a genotoxin. Whereas unrepaired damage can lead to cell death, effective, but improper repair may be detrimental. Indeed, improper repair of DNA damage may allow cells to resume the cell cycle and induce genetic instability, a hallmark in cancer. In vivo, CDT has been shown to induce the development of dysplastic nodules and to lead to genetic instability, defining CDT as a potential carcinogen. It is therefore important to characterize the outcome of the CDT-induced DNA damage and the consequences for intoxicated cells and organisms. Here, we review the latest results regarding the host cell response to CDT intoxication and focus on DNA damage characteristics, cell cycle modulation and cell outcomes.
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Affiliation(s)
- Elisabeth Bezine
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, F-31027 Toulouse, France.
| | - Julien Vignard
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, F-31027 Toulouse, France.
| | - Gladys Mirey
- INRA, UMR1331, Toxalim, Research Centre in Food Toxicology, F-31027 Toulouse, France.
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Breaking the Gingival Epithelial Barrier: Role of the Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin in Oral Infectious Disease. Cells 2014; 3:476-99. [PMID: 24861975 PMCID: PMC4092858 DOI: 10.3390/cells3020476] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 05/08/2014] [Accepted: 05/15/2014] [Indexed: 12/17/2022] Open
Abstract
The Gram-negative bacterium Aggregatibacter actinomycetemcomitans is part of the HACEK group that causes infective endocarditis, a constituent of the oral flora that promotes some forms of periodontal disease and a member of the family of species that secrete a cytolethal distending toxin (Cdt). The family of bacteria that express the cdt genes participate in diseases that involve the disruption of a mucosal or epithelial layer. In vitro studies have shown that human gingival epithelial cells (HGEC) are native targets of the Cdt that typically induces DNA damage that signals growth arrest at the G2/M interphase of the cell cycle. The gingival epithelium is an early line of defense in the oral cavity against microbial assault. When damaged, bacteria collectively gain entry into the underlying connective tissue where microbial products can affect processes and pathways in infiltrating inflammatory cells culminating in the destruction of the attachment apparatus of the tooth. One approach has been the use of an ex vivo gingival explant model to assess the effects of the Cdt on the morphology and integrity of the tissue. The goal of this review is to provide an overview of these studies and to critically examine the potential contribution of the Cdt to the breakdown of the protective gingival barrier.
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Shenker BJ, Walker LP, Zekavat A, Dlakić M, Boesze-Battaglia K. Blockade of the PI-3K signalling pathway by the Aggregatibacter actinomycetemcomitans cytolethal distending toxin induces macrophages to synthesize and secrete pro-inflammatory cytokines. Cell Microbiol 2014; 16:1391-404. [PMID: 24697951 DOI: 10.1111/cmi.12299] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 03/24/2014] [Accepted: 03/28/2014] [Indexed: 01/08/2023]
Abstract
The Aggregatibactor actinomycetemcomitans cytolethal distending toxin (Cdt) induces G2 arrest and apoptosis in lymphocytes; these toxic effects are due to the active subunit, CdtB, which functions as a phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase. We now extend our investigation and demonstrate that Cdt is able to perturb human macrophage function. THP-1- and monocyte-derived macrophages were found not to be susceptible to Cdt-induced apoptosis. Nonetheless, the toxin was capable of binding to macrophages and perturbing PI-3K signalling resulting in decreased PIP3 levels and reduced phosphorylation of Akt and GSK3β; these changes were accompanied by concomitant alterations in kinase activity. Exposure of monocytes and macrophages to Cdt resulted in pro-inflammatory cytokine production including increased expression and release of IL-1β, TNFα and IL-6. Furthermore, treatment of cells with either TLR-2, -3 or -4 agonists in the presence of Cdt resulted in an augmented pro-inflammatory response relative to agonist alone. GSK3β inhibitors blocked the Cdt-induced pro-inflammatory cytokine response suggesting a pivotal role for PI-3K blockade, concomitant decrease in GSK3β phosphorylation and increased kinase activity. Collectively, these studies provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms.
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Affiliation(s)
- Bruce J Shenker
- Department of Pathology, University of Pennsylvania School of Dental Medicine, 240 South 40th Street, Philadelphia, PA, 19104-6030, USA
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Cytolethal distending toxin B as a cell-killing component of tumor-targeted anthrax toxin fusion proteins. Cell Death Dis 2014; 5:e1003. [PMID: 24434511 PMCID: PMC4040664 DOI: 10.1038/cddis.2013.540] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 11/27/2013] [Accepted: 12/02/2013] [Indexed: 11/28/2022]
Abstract
Cytolethal distending toxin (Cdt) is produced by Gram-negative bacteria of several species. It is composed of three subunits, CdtA, CdtB, and CdtC, with CdtB being the catalytic subunit. We fused CdtB from Haemophilus ducreyi to the N-terminal 255 amino acids of Bacillus anthracis toxin lethal factor (LFn) to design a novel, potentially potent antitumor drug. As a result of this fusion, CdtB was transported into the cytosol of targeted cells via the efficient delivery mechanism of anthrax toxin. The fusion protein efficiently killed various human tumor cell lines by first inducing a complete cell cycle arrest in the G2/M phase, followed by induction of apoptosis. The fusion protein showed very low toxicity in mouse experiments and impressive antitumor effects in a Lewis Lung carcinoma model, with a 90% cure rate. This study demonstrates that efficient drug delivery by a modified anthrax toxin system combined with the enzymatic activity of CdtB has great potential as anticancer treatment and should be considered for the development of novel anticancer drugs.
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48
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Ando-Suguimoto ES, da Silva MP, Kawamoto D, Chen C, DiRienzo JM, Mayer MPA. The cytolethal distending toxin of Aggregatibacter actinomycetemcomitans inhibits macrophage phagocytosis and subverts cytokine production. Cytokine 2014; 66:46-53. [PMID: 24548424 DOI: 10.1016/j.cyto.2013.12.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 11/19/2013] [Accepted: 12/24/2013] [Indexed: 02/06/2023]
Abstract
Aggregatibacter actinomycetemcomitans is an important periodontal pathogen that can participate in periodontitis and other non-oral infections. The cytolethal distending toxin (Cdt) is among the virulence factors produced by this bacterium. The Cdt is also secreted by several mucosa-associated Gram-negative pathogens and may play a role in perpetuating the infection by modulating the immune response. Although the toxin targets a wide range of eukaryotic cell types little is known about its activity on macrophages which play a key part in alerting the rest of the immune system to the presence of pathogens and their virulence factors. In view of this, we tested the hypothesis that the A. actinomycetemcomitans Cdt (AaCdt) disrupts macrophage function by inhibiting phagocytic activity as well as affecting the production of cytokines. Murine macrophages were co-cultured with either wild-type A. actinomycetemcomitans or a Cdt(-) mutant. Viable counts and qPCR showed that phagocytosis of the wild-type strain was significantly reduced relative to that of the Cdt(-) mutant. Addition of recombinant Aa(r)Cdt to co-cultures along with the Cdt(-) mutant diminished the phagocytic activity similar to that observed with the wild type strain. High concentrations of Aa(r)Cdt resulted in decreased phagocytosis of fluorescent bioparticles. Nitric oxide production was modulated by the presence of Cdt and the levels of IL-1β, IL-12 and IL-10 were increased. Production of TNF-α did not differ in the co-culture assays but was increased by the presence of Aa(r)Cdt. These data suggest that the Cdt may modulate macrophage function in A. actinomycetemcomitans infected sites by impairing phagocytosis and modifying the pro-inflammatory/anti-inflammatory cytokine balance.
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Affiliation(s)
| | - Maike Paulino da Silva
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Dione Kawamoto
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Casey Chen
- Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Ostrow School of Dentistry of University of Southern California, USA
| | - Joseph M DiRienzo
- Department of Microbiology, School of Dental Medicine, University of Pennsylvania, PA, USA
| | - Marcia Pinto Alves Mayer
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Viernes DR, Choi LB, Kerr WG, Chisholm JD. Discovery and development of small molecule SHIP phosphatase modulators. Med Res Rev 2013; 34:795-824. [PMID: 24302498 DOI: 10.1002/med.21305] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Inositol phospholipids play an important role in the transfer of signaling information across the cell membrane in eukaryotes. These signals are often governed by the phosphorylation patterns on the inositols, which are mediated by a number of inositol kinases and phosphatases. The src homology 2 (SH2) containing inositol 5-phosphatase (SHIP) plays a central role in these processes, influencing signals delivered through the PI3K/Akt/mTOR pathway. SHIP modulation by small molecules has been implicated as a treatment in a number of human disease states, including cancer, inflammatory diseases, diabetes, atherosclerosis, and Alzheimer's disease. In addition, alteration of SHIP phosphatase activity may provide a means to facilitate bone marrow transplantation and increase blood cell production. This review discusses the cellular signaling pathways and protein-protein interactions that provide the molecular basis for targeting the SHIP enzyme in these disease states. In addition, a comprehensive survey of small molecule modulators of SHIP1 and SHIP2 is provided, with a focus on the structure, potency, selectivity, and solubility properties of these compounds.
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Affiliation(s)
- Dennis R Viernes
- Department of Chemistry, Syracuse University, Syracuse, NY, USA 13244
| | - Lydia B Choi
- Department of Chemistry, Syracuse University, Syracuse, NY, USA 13244
| | - William G Kerr
- Department of Chemistry, Syracuse University, Syracuse, NY, USA 13244.,Department of Microbiology & Immunology, SUNY Upstate Medical University, Syracuse, NY, USA 13210.,Department of Pediatrics, SUNY Upstate Medical University, Syracuse, NY, USA 13210
| | - John D Chisholm
- Department of Chemistry, Syracuse University, Syracuse, NY, USA 13244
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Lai CK, Lu YL, Hsieh JT, Tsai SC, Feng CL, Tsai YS, Tsai PC, Su HL, Lin YH, Lai CH. Development of chitosan/heparin nanoparticle-encapsulated cytolethal distending toxin for gastric cancer therapy. Nanomedicine (Lond) 2013; 9:803-17. [PMID: 24024568 DOI: 10.2217/nnm.13.54] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
AIM The aim of this work was to develop pH-responsive nanoparticles encapsulating CdtB and to demonstrate that these particles represent a potential therapeutic agent for gastric cancer. MATERIALS & METHODS Chitosan/heparin nanoparticle-encapsulated CdtB was prepared and the delivery efficiency was monitored by confocal laser scanning microscopy. The molecular basis of the nanoparticle-encapsulated CdtB-mediated p53 activation pathway was explored by immunoblot analysis. Antitumoral activities were investigated by analyzing the cell cycle and apoptosis. RESULTS Chitosan/heparin nanoparticle-encapsulated CdtB preferentially inhibited the proliferation of cells derived from gastric cancer, but not in primary gastric epithelial cells. Treatment of cells with nanoparticle-encapsulated CdtB enhanced cell-cycle arrest at G2/M, followed by apoptosis. Moreover, our data showed that the mechanism for nanoparticle-encapsulated CdtB-induced cell death was mediated by ATM-dependent DNA damage checkpoint responses. CONCLUSION These findings indicate that chitosan/heparin nanoparticle-encapsulated CdtB could represent a new CdtB delivery strategy for the treatment of gastric cancer.
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Affiliation(s)
- Cheng-Kuo Lai
- Department of Life Sciences, Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
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