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Foulon M, Pouchin A, Manry J, Khater F, Robbe-Saule M, Durand A, Esnault L, Delneste Y, Jeannin P, Saint-André JP, Croué A, Altare F, Abel L, Alcaïs A, Marion E. Skin-specific antibodies neutralizing mycolactone toxin during the spontaneous healing of Mycobacterium ulcerans infection. SCIENCE ADVANCES 2020; 6:eaax7781. [PMID: 32133396 PMCID: PMC7043917 DOI: 10.1126/sciadv.aax7781] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 11/25/2019] [Indexed: 06/10/2023]
Abstract
Buruli ulcer, a neglected tropical infectious disease, is caused by Mycobacterium ulcerans. Without treatment, its lesions can progress to chronic skin ulcers, but spontaneous healing is observed in 5% of cases, suggesting the possible establishment of a host strategy counteracting the effects of M. ulcerans. We reveal here a skin-specific local humoral signature of the spontaneous healing process, associated with a rise in antibody-producing cells and specific recognition of mycolactone by the mouse IgG2a immunoglobulin subclass. We demonstrate the production of skin-specific antibodies neutralizing the immunomodulatory activity of the mycolactone toxin, and confirm the role of human host machinery in triggering effective local immune responses by the detection of anti-mycolactone antibodies in patients with Buruli ulcer. Our findings pave the way for substantial advances in both the diagnosis and treatment of Buruli ulcer in accordance with the most recent challenges issued by the World Health Organization.
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Affiliation(s)
- Mélanie Foulon
- Equipe ATOMycA, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
| | - Amélie Pouchin
- Equipe ATOMycA, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
| | - Jérémy Manry
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale (INSERM) UMR-1163, Paris, France
- Imagine Institute, Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Fida Khater
- Equipe ATOMycA, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
| | - Marie Robbe-Saule
- Equipe ATOMycA, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
| | - Amandine Durand
- Equipe ATOMycA, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
| | - Lucille Esnault
- Equipe ATOMycA, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
| | - Yves Delneste
- Equipe 07, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
- CHU Angers, Département d'Immunologie et Allergologie, Angers, France
| | - Pascale Jeannin
- Equipe 07, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
- CHU Angers, Département d'Immunologie et Allergologie, Angers, France
| | | | - Anne Croué
- Pathology Department, University Hospital of Angers, 49933 Angers, France
| | - Frederic Altare
- Equipe 05, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université d’Angers, Université de Nantes, Nantes, France
| | - Laurent Abel
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale (INSERM) UMR-1163, Paris, France
- Imagine Institute, Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Alexandre Alcaïs
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale (INSERM) UMR-1163, Paris, France
- Imagine Institute, Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Estelle Marion
- Equipe ATOMycA, U1232 CRCINA, Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes, Université d’Angers, Angers, France
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52
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Van Puyenbroeck V, Pauwels E, Provinciael B, Bell TW, Schols D, Kalies KU, Hartmann E, Vermeire K. Preprotein signature for full susceptibility to the co-translational translocation inhibitor cyclotriazadisulfonamide. Traffic 2019; 21:250-264. [PMID: 31675144 DOI: 10.1111/tra.12713] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/24/2019] [Accepted: 10/26/2019] [Indexed: 01/13/2023]
Abstract
Cyclotriazadisulfonamide (CADA) inhibits the co-translational translocation of human CD4 (huCD4) into the endoplasmic reticulum lumen in a signal peptide (SP)-dependent way. We propose that CADA binds the nascent huCD4 SP in a folded conformation within the translocon resembling a normally transitory state during translocation. Here, we used alanine scanning on the huCD4 SP to identify the signature for full susceptibility to CADA. In accordance with our previous work, we demonstrate that residues in the vicinity of the hydrophobic h-region are critical for sensitivity to CADA. In particular, exchanging Gln-15, Val-17 or Pro-20 in the huCD4 SP for Ala resulted in a resistant phenotype. Together with positively charged residues at the N-terminal portion of the mature protein, these residues mediate full susceptibility to the co-translational translocation inhibitory activity of CADA towards huCD4. In addition, sensitivity to CADA is inversely related to hydrophobicity in the huCD4 SP. In vitro translocation experiments confirmed that the general hydrophobicity of the h-domain and positive charges in the mature protein are key elements that affect both the translocation efficiency of huCD4 and the sensitivity towards CADA. Besides these two general SP parameters that determine the functionality of the signal sequence, unique amino acid pairs (L14/Q15 and L19/P20) in the SP hydrophobic core add specificity to the sensitivity signature for a co-translational translocation inhibitor.
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Affiliation(s)
- Victor Van Puyenbroeck
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Eva Pauwels
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Becky Provinciael
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Thomas W Bell
- Department of Chemistry, University of Nevada, Reno, Nevada
| | - Dominique Schols
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Kai-Uwe Kalies
- Centre for Structural and Cell Biology in Medicine, Institute of Biology, University of Lübeck, Lübeck, Germany
| | - Enno Hartmann
- Centre for Structural and Cell Biology in Medicine, Institute of Biology, University of Lübeck, Lübeck, Germany
| | - Kurt Vermeire
- KU Leuven Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Virology and Chemotherapy, Leuven, Belgium
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53
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Simmonds RE. Transient up-regulation of miR-155-3p by lipopolysaccharide in primary human monocyte-derived macrophages results in RISC incorporation but does not alter TNF expression. Wellcome Open Res 2019; 4:43. [PMID: 31641696 PMCID: PMC6790912 DOI: 10.12688/wellcomeopenres.15065.2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2019] [Indexed: 12/12/2022] Open
Abstract
Background: The innate immune response is a tightly regulated process that reacts rapidly in response to pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS). Evidence is accumulating that microRNAs contribute to this, although few studies have examined the early events that constitute the “primary” response. Methods: LPS-dependent changes to miRNA expression were studied in primary human monocyte-derived macrophages (1°MDMs). An unbiased screen by microarray was validated by qPCR and a method for the absolute quantitation of miRNAs was also developed, utilising 5’ phosphorylated RNA oligonucleotide templates. RNA immunoprecipitation was performed to explore incorporation of miRNAs into the RNA-induced silencing complex (RISC). The effect of miRNA functional inhibition on TNF expression (mRNA and secretion) was investigated. Results: Of the 197 miRNAs expressed in 1°MDMs, only five were induced >1.5-fold. The most strongly induced was miR-155-3p, the partner strand to miR-155-5p, which are both derived from the MIR155HG/BIC gene (pri-miR-155). The abundance of miR-155-3p was induced transiently ~250-fold at 2-4hrs and then returned towards baseline, mirroring pri-miR-155. Other PAMPs, IL-1β, and TNF caused similar responses. IL-10, NF-κB, and JNK inhibition reduced these responses, unlike cytokine-suppressing mycolactone. Absolute quantitation revealed that miRNA abundance varies widely from donor-to-donor, and showed that miR-155-3p abundance is substantially less than miR-155-5p in unstimulated cells. However, at its peak there were 446-1,113 copies/cell, and miR-155-3p was incorporated into the RISC with an efficiency similar to miR-16-5p and miR-155-5p. Inhibition of neither miRNA affected TNF secretion after 2hrs in 1°MDMs, but technical challenges here are noted. Conclusions: Dynamic regulation of miRNAs during the primary response is rare, with the exception of miR-155-3p. Further work is required to establish whether its low abundance, even at the transient peak, is sufficient for biological activity and to determine whether there are specific mechanisms determining its biogenesis from miR-155 precursors
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Affiliation(s)
- Rachel E Simmonds
- Department of Microbial Sciences, University of Surrey, Guildford, GU2 7XH, UK.,Cytokine and Signal Transduction Laboratory, Kennedy Institute of Rheumatology, London, W6 8LH, UK
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54
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Reynaert ML, Dupoiron D, Yeramian E, Marsollier L, Brodin P. Could Mycolactone Inspire New Potent Analgesics? Perspectives and Pitfalls. Toxins (Basel) 2019; 11:toxins11090516. [PMID: 31487908 PMCID: PMC6783859 DOI: 10.3390/toxins11090516] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/26/2019] [Accepted: 09/03/2019] [Indexed: 12/20/2022] Open
Abstract
Pain currently represents the most common symptom for which medical attention is sought by patients. The available treatments have limited effectiveness and significant side-effects. In addition, most often, the duration of analgesia is short. Today, the handling of pain remains a major challenge. One promising alternative for the discovery of novel potent analgesics is to take inspiration from Mother Nature; in this context, the detailed investigation of the intriguing analgesia implemented in Buruli ulcer, an infectious disease caused by the bacterium Mycobacterium ulcerans and characterized by painless ulcerative lesions, seems particularly promising. More precisely, in this disease, the painless skin ulcers are caused by mycolactone, a polyketide lactone exotoxin. In fact, mycolactone exerts a wide range of effects on the host, besides being responsible for analgesia, as it has been shown notably to modulate the immune response or to provoke apoptosis. Several cellular mechanisms and different targets have been proposed to account for the analgesic effect of the toxin, such as nerve degeneration, the inhibition of inflammatory mediators and the activation of angiotensin II receptor 2. In this review, we discuss the current knowledge in the field, highlighting possible controversies. We first discuss the different pain-mimicking experimental models that were used to study the effect of mycolactone. We then detail the different variants of mycolactone that were used in such models. Overall, based on the results and the discussions, we conclude that the development of mycolactone-derived molecules can represent very promising perspectives for new analgesic drugs, which could be effective for specific pain indications.
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Affiliation(s)
- Marie-Line Reynaert
- France Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Denis Dupoiron
- Institut de Cancérologie de l'Ouest Paul Papin, 15 rue André Boquel-49055 Angers, France
| | - Edouard Yeramian
- Unité de Microbiologie Structurale, Institut Pasteur, CNRS, Univ. Paris, F-75015 Paris, France
| | - Laurent Marsollier
- Equipe ATIP AVENIR, CRCINA, INSERM, Univ. Nantes, Univ. Angers, 4 rue Larrey, F-49933 Angers, France.
| | - Priscille Brodin
- France Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR8204-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France.
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55
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Aydin F, Sun R, Swanson JMJ. Mycolactone Toxin Membrane Permeation: Atomistic versus Coarse-Grained MARTINI Simulations. Biophys J 2019; 117:87-98. [PMID: 31174850 PMCID: PMC6626831 DOI: 10.1016/j.bpj.2019.05.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 05/02/2019] [Accepted: 05/07/2019] [Indexed: 02/06/2023] Open
Abstract
Mycolactone, a cytotoxic and immunosuppressive macrolide produced by Mycobacterium ulcerans, is the central virulent factor in the skin disease Buruli ulcer. This multifunctional cytotoxin affects fundamental cellular processes such as cell adhesion, immune response, and cell death by targeting various cellular structures. Developing effective diagnostics that target mycolactone has been challenging, potentially because of suspected interactions with lipophilic architectures, including membranes. To better understand the pathogenesis of Buruli ulcer disease, aid in the development of diagnostics, and learn how amphiphiles in general use lipid trafficking to navigate the host environment, we seek to understand the nature of mycolactone-membrane interactions. Herein, we characterize how the two dominant isomers of mycolactone (A and B) interact with and permeate DPPC membranes with all-atom molecular dynamics simulations employing transition-tempered metadynamics and compare these results to those obtained by MARTINI coarse-grained simulations. Our all-atom simulations reveal that both isomers have a strong preference to associate with the membrane, although their mechanisms and energetics of membrane permeation differ slightly. Water molecules are found to play an important role in the permeation process. Although the MARTINI coarse-grained simulations give the correct free energy of membrane association, they fail to capture the mechanism of permeation and role of water during permeation as seen in all-atom simulations.
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Affiliation(s)
- Fikret Aydin
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois
| | - Rui Sun
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois
| | - Jessica M J Swanson
- Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois.
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56
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Molecular Informatics Studies of the Iron-Dependent Regulator (ideR) Reveal Potential Novel Anti- Mycobacterium ulcerans Natural Product-Derived Compounds. Molecules 2019; 24:molecules24122299. [PMID: 31234337 PMCID: PMC6631925 DOI: 10.3390/molecules24122299] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/20/2019] [Accepted: 05/29/2019] [Indexed: 02/02/2023] Open
Abstract
Buruli ulcer is a neglected tropical disease caused by the bacterium Mycobacterium ulcerans. Its virulence is attributed to the dermo-necrotic polyketide toxin mycolactone, whose synthesis is regressed when its iron acquisition system regulated by the iron-dependent regulator (ideR) is deactivated. Interfering with the activation mechanism of ideR to inhibit the toxin’s synthesis could serve as a possible cure for Buruli ulcer. The three-dimensional structure of the ideR for Mycobacterium ulcerans was generated using homology modeling. A library of 832 African natural products (AfroDB), as well as five known anti-mycobacterial compounds were docked against the metal binding site of the ideR. The area under the curve (AUC) values greater than 0.7 were obtained for the computed Receiver Operating Characteristics (ROC) curves, validating the docking protocol. The identified top hits were pharmacologically profiled using Absorption, Distribution, Metabolism, Elimination and Toxicity (ADMET) predictions and their binding mechanisms were characterized. Four compounds with ZINC IDs ZINC000018185774, ZINC000095485921, ZINC000014417338 and ZINC000005357841 emerged as leads with binding energies of −7.7 kcal/mol, −7.6 kcal/mol, −8.0 kcal/mol and −7.4 kcal/mol, respectively. Induced Fit Docking (IFD) was also performed to account for the protein’s flexibility upon ligand binding and to estimate the best plausible conformation of the complexes. Results obtained from the IFD were consistent with that of the molecular docking with the lead compounds forming interactions with known essential residues and some novel critical residues Thr14, Arg33 and Asp17. A hundred nanoseconds molecular dynamic simulations of the unbound ideR and its complexes with the respective lead compounds revealed changes in the ideR’s conformations induced by ZINC000018185774. Comparison of the lead compounds to reported potent inhibitors by docking them against the DNA-binding domain of the protein also showed the lead compounds to have very close binding affinities to those of the potent inhibitors. Interestingly, structurally similar compounds to ZINC000018185774 and ZINC000014417338, as well as analogues of ZINC000095485921, including quercetin are reported to possess anti-mycobacterial activity. Also, ZINC000005357841 was predicted to possess anti-inflammatory and anti-oxidative activities, which are relevant in Buruli ulcer and iron acquisition mechanisms, respectively. The leads are molecular templates which may serve as essential scaffolds for the design of future anti-mycobacterium ulcerans agents.
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57
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Zong G, Hu Z, O’Keefe S, Tranter D, Iannotti MJ, Baron L, Hall B, Corfield K, Paatero AO, Henderson MJ, Roboti P, Zhou J, Sun X, Govindarajan M, Rohde JM, Blanchard N, Simmonds R, Inglese J, Du Y, Demangel C, High S, Paavilainen VO, Shi WQ. Ipomoeassin F Binds Sec61α to Inhibit Protein Translocation. J Am Chem Soc 2019; 141:8450-8461. [PMID: 31059257 PMCID: PMC6627486 DOI: 10.1021/jacs.8b13506] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ipomoeassin F is a potent natural cytotoxin that inhibits growth of many tumor cell lines with single-digit nanomolar potency. However, its biological and pharmacological properties have remained largely unexplored. Building upon our earlier achievements in total synthesis and medicinal chemistry, we used chemical proteomics to identify Sec61α (protein transport protein Sec61 subunit alpha isoform 1), the pore-forming subunit of the Sec61 protein translocon, as a direct binding partner of ipomoeassin F in living cells. The interaction is specific and strong enough to survive lysis conditions, enabling a biotin analogue of ipomoeassin F to pull down Sec61α from live cells, yet it is also reversible, as judged by several experiments including fluorescent streptavidin staining, delayed competition in affinity pulldown, and inhibition of TNF biogenesis after washout. Sec61α forms the central subunit of the ER protein translocation complex, and the binding of ipomoeassin F results in a substantial, yet selective, inhibition of protein translocation in vitro and a broad ranging inhibition of protein secretion in live cells. Lastly, the unique resistance profile demonstrated by specific amino acid single-point mutations in Sec61α provides compelling evidence that Sec61α is the primary molecular target of ipomoeassin F and strongly suggests that the binding of this natural product to Sec61α is distinctive. Therefore, ipomoeassin F represents the first plant-derived, carbohydrate-based member of a novel structural class that offers new opportunities to explore Sec61α function and to further investigate its potential as a therapeutic target for drug discovery.
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Affiliation(s)
- Guanghui Zong
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Chemistry and Biochemistry, University
of Maryland, College Park, Maryland 20742, United States
| | - Zhijian Hu
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Sarah O’Keefe
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Dale Tranter
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland
| | - Michael J. Iannotti
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Ludivine Baron
- Immunobiology
of Infection Unit, Institut Pasteur, 75015 Paris, France,INSERM, U1221, 75005 Paris, France
| | - Belinda Hall
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Katherine Corfield
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
| | - Anja O. Paatero
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland
| | - Mark J. Henderson
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Peristera Roboti
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom
| | - Jianhong Zhou
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Xianwei Sun
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Radiology, Baylor College of Medicine, Houston, Texas 77030, United States
| | - Mugunthan Govindarajan
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Emory
Institute for Drug Development, Emory University, 954 Gatewood Road, Atlanta, Georgia 30329, United States
| | - Jason M. Rohde
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States
| | - Nicolas Blanchard
- Université
de Haute-Alsace, Université de Strasbourg, CNRS, LIMA, UMR 7042, 68000 Mulhouse, France
| | - Rachel Simmonds
- Department
of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom,
| | - James Inglese
- National
Center for Advancing Translational Sciences, National
Institutes of Health, Rockville, Maryland 20850, United States,
| | - Yuchun Du
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,
| | - Caroline Demangel
- Immunobiology
of Infection Unit, Institut Pasteur, 75015 Paris, France,INSERM, U1221, 75005 Paris, France,
| | - Stephen High
- School
of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, United Kingdom,
| | - Ville O. Paavilainen
- University
of Helsinki, HiLIFE, Helsinki, Finland,Institute
of Biotechnology, Helsinki, Finland,
| | - Wei Q. Shi
- †Department
of Chemistry and Biochemistry and ⬡Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas 72701, United States,Department
of Chemistry, Ball State University, Muncie, Indiana 47306, United States,;
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58
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Babonneau J, Bréard D, Reynaert ML, Marion E, Guilet D, Saint André JP, Croué A, Brodin P, Richomme P, Marsollier L. Mycolactone as Analgesic: Subcutaneous Bioavailability Parameters. Front Pharmacol 2019; 10:378. [PMID: 31031626 PMCID: PMC6473063 DOI: 10.3389/fphar.2019.00378] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 03/26/2019] [Indexed: 01/09/2023] Open
Abstract
Mycobacterium ulcerans is the bacillus responsible for Buruli ulcer, an infectious disease and the third most important mycobacterial disease worldwide, after tuberculosis and leprosy. M. ulcerans infection is a type of panniculitis beginning mostly with a nodule or an oedema, which can progress to large ulcerative lesions. The lesions are caused by mycolactone, the polyketide toxin of M. ulcerans. Mycolactone plays a central role for host colonization as it has immunomodulatory and analgesic effects. On one hand, mycolactone induces analgesia by targeting type-2 angiotensin II receptors (AT2R), causing cellular hyperpolarization and neuron desensitization. Indeed, a single subcutaneous injection of mycolactone into the mouse footpad induces a long-lasting hypoesthesia up to 48 h. It was suggested that the long-lasting hypoesthesia may result from the persistence of a significant amount of mycolactone locally following its injection, which could be probably due to its slow elimination from tissues. To verify this hypothesis, we investigated the correlation between hypoesthesia and mycolactone bioavailability directly at the tissue level. Various quantities of mycolactone were then injected in mouse tissue and hypoesthesia was recorded with nociception assays over a period of 48 h. The hypoesthesia was maximal 6 h after the injection of 4 μg mycolactone. The basal state was reached 48 h after injection, which demonstrated the absence of nerve damage. Surprisingly, mycolactone levels decreased strongly during the first hours with a reduction of 70 and 90% after 4 and 10 h, respectively. Also, mycolactone did not diffuse in neighboring skin tissue and only poorly into the bloodstream upon direct injection. Nevertheless, the remaining amount was sufficient to induce hypoesthesia during 24 h. Our results thus demonstrate that intact mycolactone is rapidly eliminated and that very small amounts of mycolactone are sufficient to induce hypoesthesia. Taken together, our study points out that mycolactone ought to be considered as a promising analgesic.
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Affiliation(s)
- Jérémie Babonneau
- Equipe ATIP AVENIR, CRCINA, INSERM, University of Nantes, University of Angers, Angers, France
| | - Dimitri Bréard
- EA921 SONAS, SFR4207 QUASAV, University of Angers, Université Bretagne-Loire, Angers, France
| | - Marie-Line Reynaert
- CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR8204 - CIIL - Center for Infection and Immunity of Lille, University of Lille, Lille, France
| | - Estelle Marion
- Equipe ATIP AVENIR, CRCINA, INSERM, University of Nantes, University of Angers, Angers, France
| | - David Guilet
- EA921 SONAS, SFR4207 QUASAV, University of Angers, Université Bretagne-Loire, Angers, France
| | | | - Anne Croué
- Laboratoire d'Anatomie Pathologique, Angers, France
| | - Priscille Brodin
- CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019 - UMR8204 - CIIL - Center for Infection and Immunity of Lille, University of Lille, Lille, France
| | - Pascal Richomme
- EA921 SONAS, SFR4207 QUASAV, University of Angers, Université Bretagne-Loire, Angers, France
| | - Laurent Marsollier
- Equipe ATIP AVENIR, CRCINA, INSERM, University of Nantes, University of Angers, Angers, France
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59
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Molecular Docking and Dynamics Simulation Studies Predict Munc18b as a Target of Mycolactone: A Plausible Mechanism for Granule Exocytosis Impairment in Buruli Ulcer Pathogenesis. Toxins (Basel) 2019; 11:toxins11030181. [PMID: 30934618 PMCID: PMC6468854 DOI: 10.3390/toxins11030181] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/15/2019] [Accepted: 03/20/2019] [Indexed: 12/18/2022] Open
Abstract
Ulcers due to infections with Mycobacterium ulcerans are characterized by complete lack of wound healing processes, painless, an underlying bed of host dead cells and undermined edges due to necrosis. Mycolactone, a macrolide produced by the mycobacterium, is believed to be the toxin responsible. Of interest and relevance is the knowledge that Buruli ulcer (BU) patients remember experiencing trauma previously at the site of the ulcers, suggesting an impairment of wound healing processes, the plausible effect due to the toxin. Wound healing processes involve activation of the blood platelets to release the contents of the dense granules mainly serotonin, calcium ions, and ADP/ATP by exocytosis into the bloodstream. The serotonin release results in attracting more platelets and mast cells to the wound site, with the mast cells also undergoing degranulation, releasing compounds into the bloodstream by exocytosis. Recent work has identified interference in the co-translational translocation of many secreted proteins via the endoplasmic reticulum and cell death involving Wiskott-Aldrich syndrome protein (WASP), Sec61, and angiotensin II receptors (AT2R). We hypothesized that mycolactone by being lipophilic, passively crosses cell membranes and binds to key proteins that are involved in exocytosis by platelets and mast cells, thus inhibiting the initiation of wound healing processes. Based on this, molecular docking studies were performed with mycolactone against key soluble n-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and regulators, namely Vesicle-associated membrane protein (VAMP8), Synaptosomal-associated protein (SNAP23, syntaxin 11, Munc13-4 (its isoform Munc13-1 was used), and Munc18b; and also against known mycolactone targets (Sec61, AT2R, and WASP). Munc18b was shown to be a plausible mycolactone target after the molecular docking studies with binding affinity of -8.5 kcal/mol. Structural studies and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) binding energy calculations of the mycolactone and Munc18b complex was done with 100 ns molecular dynamics simulations using GROMACS. Mycolactone binds strongly to Munc18b with an average binding energy of -247.571 ± 37.471 kJ/mol, and its presence elicits changes in the structural conformation of the protein. Analysis of the binding interactions also shows that mycolactone interacts with Arg405, which is an important residue of Munc18b, whose mutation could result in impaired granule exocytosis. These findings consolidate the possibility that Munc18b could be a target of mycolactone. The implication of the interaction can be experimentally evaluated to further understand its role in granule exocytosis impairment in Buruli ulcer.
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Simmonds RE. Transient up-regulation of miR-155-3p by lipopolysaccharide in primary human monocyte-derived macrophages results in RISC incorporation but does not alter TNF expression. Wellcome Open Res 2019; 4:43. [DOI: 10.12688/wellcomeopenres.15065.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/21/2019] [Indexed: 12/18/2022] Open
Abstract
Background: The innate immune response is a tightly regulated process that reacts rapidly in response to pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS). Evidence is accumulating that microRNAs contribute to this, although few studies have examined the early events that constitute the “primary” response. Methods: LPS-dependent changes to miRNA expression were studied in primary human monocyte-derived macrophages (1°MDMs). An unbiased screen by microarray was validated by qPCR and a method for the absolute quantitation of miRNAs was also developed, utilising 5’ phosphorylated RNA oligonucleotide templates. RNA immunoprecipitation was performed to explore incorporation of miRNAs into the RNA-induced silencing complex (RISC). The effect of miRNA functional inhibition on TNF expression (mRNA and secretion) was investigated. Results: Of the 197 miRNAs expressed in 1°MDMs, only five were induced >1.5-fold. The most strongly induced was miR-155-3p, the partner strand to miR-155-5p, which are both derived from the BIC gene (B cell integration cluster, MIR155HG). The abundance of miR-155-3p was induced transiently ~250-fold at 2-4hrs and then returned towards baseline, mirroring the BIC mRNA. Other PAMPs, IL-1β, and TNF caused similar responses. IL-10, NF-κB, and JNK inhibition suppressed these responses, unlike cytokine-suppressing mycolactone. Absolute quantitation showed that miRNA abundance varies widely from donor-to-donor, and showed that miR-155-3p abundance is substantially less than miR-155-5p in unstimulated cells. However, at its peak there were 446-1,113 copies/cell, and miR-155-3p was incorporated into the RISC with an efficiency similar to miR-16-5p and miR-155-5p. Inhibition of neither miRNA affected TNF expression in 1°MDMs, but technical challenges here are noted. Conclusions: Dynamic regulation of miRNAs during the primary response is rare, with the exception of miR-155-3p, which transiently achieves levels that might have a biological effect. Further work on this candidate would need to overcome the technical challenges of the broad-ranging effects of liposomes on 1°MDMs.
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Klein W, Rutz C, Eckhard J, Provinciael B, Specker E, Neuenschwander M, Kleinau G, Scheerer P, von Kries JP, Nazaré M, Vermeire K, Schülein R. Use of a sequential high throughput screening assay to identify novel inhibitors of the eukaryotic SRP-Sec61 targeting/translocation pathway. PLoS One 2018; 13:e0208641. [PMID: 30543669 PMCID: PMC6292634 DOI: 10.1371/journal.pone.0208641] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 11/20/2018] [Indexed: 11/22/2022] Open
Abstract
The SRP-Sec61 targeting/translocation pathway of eukaryotic cells targets nascent protein chains to the membrane of the endoplasmic reticulum. Using this machinery, secretory proteins are translocated across this membrane whereas membrane proteins are integrated into the lipid bilayer. One of the key players of the pathway is the protein-conducting Sec61 (translocon) complex of the endoplasmic reticulum. The Sec61 complex has no enzymatic activity, is expressed only intracellularly and is difficult to purify and to reconstitute. Screening for small molecule inhibitors impairing its functions is thus notoriously difficult. Such inhibitors may not only be valuable tools for cell biology, they may also represent novel anti-tumor drugs. Here we have developed a two-step, sequential screening assay for inhibitors of the whole SRP-Sec61 targeting/translocation pathway which might include molecules affecting Sec61 complex functions. The resulting hit compounds were analyzed using a whole cell biosynthesis assay and a cell free transcription/translation/translocation assay. Using this methodology, we identified novel compounds inhibiting this pathway. Following structure-based back screening, one of these substances was analyzed in more detail and we could show that it indeed impairs translocation at the level of the Sec61 complex. A slightly modified methodology may be used in the future to screen for substances affecting SecYEG, the bacterial ortholog of the Sec61 complex in order to derive novel antibiotic drugs.
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Affiliation(s)
- Wolfgang Klein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Claudia Rutz
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Jamina Eckhard
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Becky Provinciael
- KU Leuven, Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Edgar Specker
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | | | - Gunnar Kleinau
- Charité—Universitätsmedizin Berlin, Campus Charité Mitte, Charité Centrum Grundlagenmedizin CC2, Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | - Patrick Scheerer
- Charité—Universitätsmedizin Berlin, Campus Charité Mitte, Charité Centrum Grundlagenmedizin CC2, Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography & Signal Transduction, Berlin, Germany
| | | | - Marc Nazaré
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Kurt Vermeire
- KU Leuven, Department of Microbiology and Immunology, Rega Institute, Laboratory of Virology and Chemotherapy, Leuven, Belgium
| | - Ralf Schülein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
- * E-mail:
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Abstract
Humans encounter mycobacterial species due to their ubiquity in different environmental niches. In many individuals, pathogenic mycobacterial species may breach our first-line barrier defenses of the innate immune system and modulate the activation of phagocytes to cause disease of the respiratory tract or the skin and soft tissues, sometimes resulting in disseminated infection. Cutaneous mycobacterial infections may cause a wide range of clinical manifestations, which are divided into four main disease categories: (i) cutaneous manifestations of Mycobacterium tuberculosis infection, (ii) Buruli ulcer caused by Mycobacterium ulcerans and other related slowly growing mycobacteria, (iii) leprosy caused by Mycobacterium leprae and Mycobacterium lepromatosis, and (iv) cutaneous infections caused by rapidly growing mycobacteria. Clinically, cutaneous mycobacterial infections present with widely different clinical presentations, including cellulitis, nonhealing ulcers, subacute or chronic nodular lesions, abscesses, superficial lymphadenitis, verrucous lesions, and other types of findings. Mycobacterial infections of the skin and subcutaneous tissue are associated with important stigma, deformity, and disability. Geography-based environmental exposures influence the epidemiology of cutaneous mycobacterial infections. Cutaneous tuberculosis exhibits different clinical phenotypes acquired through different routes, including via extrinsic inoculation of the tuberculous bacilli and dissemination to the skin from other sites, or represents hypersensitivity reactions to M. tuberculosis infection. In many settings, leprosy remains an important cause of neurological impairment, deformity, limb loss, and stigma. Mycobacterium lepromatosis, a mycobacterial species related to M. leprae, is linked to diffuse lepromatous leprosy of Lucio and Latapí. Mycobacterium ulcerans produces a mycolactone toxin that leads to subcutaneous tissue destruction and immunosuppression, resulting in deep ulcerations that often produce substantial disfigurement and disability. Mycobacterium marinum, a close relative of M. ulcerans, is an important cause of cutaneous sporotrichoid nodular lymphangitic lesions. Among patients with advanced immunosuppression, Mycobacterium kansasii, the Mycobacterium avium-intracellulare complex, and Mycobacterium haemophilum may cause cutaneous or disseminated disease. Rapidly growing mycobacteria, including the Mycobacterium abscessus group, Mycobacterium chelonei, and Mycobacterium fortuitum, are increasingly recognized pathogens in cutaneous infections associated particularly with plastic surgery and cosmetic procedures. Skin biopsies of cutaneous lesions to identify acid-fast staining bacilli and cultures represent the cornerstone of diagnosis. Additionally, histopathological evaluation of skin biopsy specimens may be useful in identifying leprosy, Buruli ulcer, and cutaneous tuberculosis. Molecular assays are useful in some cases. The treatment for cutaneous mycobacterial infections depends on the specific pathogen and therefore requires a careful consideration of antimicrobial choices based on official treatment guidelines.
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Aboagye SY, Kpeli G, Tuffour J, Yeboah‐Manu D. Challenges associated with the treatment of Buruli ulcer. J Leukoc Biol 2018; 105:233-242. [PMID: 30168876 DOI: 10.1002/jlb.mr0318-128] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 07/19/2018] [Indexed: 12/30/2022] Open
Affiliation(s)
- Sammy Yaw Aboagye
- Noguchi Memorial Institute for Medical ResearchUniversity of Ghana Accra Ghana
| | - Grace Kpeli
- University of Allied Health Sciences Ho Ghana
| | | | - Dorothy Yeboah‐Manu
- Noguchi Memorial Institute for Medical ResearchUniversity of Ghana Accra Ghana
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64
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Demangel C, High S. Sec61 blockade by mycolactone: A central mechanism in Buruli ulcer disease. Biol Cell 2018; 110:237-248. [PMID: 30055020 DOI: 10.1111/boc.201800030] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/19/2018] [Indexed: 12/14/2022]
Abstract
Infection with Mycobacterium ulcerans results in a necrotising skin disease known as a Buruli ulcer, the pathology of which is directly linked to the bacterial production of the toxin mycolactone. Recent studies have identified the protein translocation machinery of the endoplasmic reticulum (ER) membrane as the primary cellular target of mycolactone, and shown that the toxin binds to the core subunit of the Sec61 complex. Mycolactone binding strongly inhibits the capacity of the Sec61 translocon to transport newly synthesised membrane and secretory proteins into and across the ER membrane. Since the ER acts as the entry point for the mammalian secretory pathway, and hence regulates initial access to the entire endomembrane system, mycolactone-treated cells have a reduced ability to produce a range of proteins including secretory cytokines and plasma membrane receptors. The global effect of this molecular blockade of protein translocation at the ER is that the host is unable to mount an effective immune response to the underlying mycobacterial infection. Prolonged exposure to mycolactone is normally cytotoxic, since it triggers stress responses activating the transcription factor ATF4 and ultimately inducing apoptosis.
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Affiliation(s)
- Caroline Demangel
- Immunobiology of Infection Unit, Institut Pasteur, Paris, France.,INSERM, U1221, Paris, France
| | - Stephen High
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
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Embgenbroich M, Burgdorf S. Current Concepts of Antigen Cross-Presentation. Front Immunol 2018; 9:1643. [PMID: 30061897 PMCID: PMC6054923 DOI: 10.3389/fimmu.2018.01643] [Citation(s) in RCA: 245] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/04/2018] [Indexed: 12/15/2022] Open
Abstract
Dendritic cells have the ability to efficiently present internalized antigens on major histocompatibility complex (MHC) I molecules. This process is termed cross-presentation and is important role in the generation of an immune response against viruses and tumors, after vaccinations or in the induction of immune tolerance. The molecular mechanisms enabling cross-presentation have been topic of intense debate since many years. However, a clear view on these mechanisms remains difficult, partially due to important remaining questions, controversial results and discussions. Here, we give an overview of the current concepts of antigen cross-presentation and focus on a description of the major cross-presentation pathways, the role of retarded antigen degradation for efficient cross-presentation, the dislocation of antigens from endosomal compartment into the cytosol, the reverse transport of proteasome-derived peptides for loading on MHC I and the translocation of the cross-presentation machinery from the ER to endosomes. We try to highlight recent advances, discuss some of the controversial data and point out some of the major open questions in the field.
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Affiliation(s)
- Maria Embgenbroich
- Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
| | - Sven Burgdorf
- Life and Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany
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Morel JD, Paatero AO, Wei J, Yewdell JW, Guenin-Macé L, Van Haver D, Impens F, Pietrosemoli N, Paavilainen VO, Demangel C. Proteomics Reveals Scope of Mycolactone-mediated Sec61 Blockade and Distinctive Stress Signature. Mol Cell Proteomics 2018; 17:1750-1765. [PMID: 29915147 DOI: 10.1074/mcp.ra118.000824] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 06/17/2018] [Indexed: 11/06/2022] Open
Abstract
Mycolactone is a bacteria-derived macrolide that blocks the biogenesis of a large array of secretory and integral transmembrane proteins (TMP) through potent inhibition of the Sec61 translocon. Here, we used quantitative proteomics to delineate the direct and indirect effects of mycolactone-mediated Sec61 blockade in living cells. In T lymphocytes, dendritic cells and sensory neurons, Sec61 substrates downregulated by mycolactone were in order of incidence: secretory proteins (with a signal peptide but no transmembrane domain), TMPs with a signal peptide (Type I) and TMPs without signal peptide and a cytosolic N terminus (Type II). TMPs without a signal peptide and the opposite N terminus topology (Type III) were refractory to mycolactone inhibition. This rule applied comparably to single- and multi-pass TMPs, and extended to exogenous viral proteins. Parallel to its broad-spectrum inhibition of Sec61-mediated protein translocation, mycolactone rapidly induced cytosolic chaperones Hsp70/Hsp90. Moreover, it activated an atypical endoplasmic reticulum stress response, differing from conventional unfolded protein response by the down-regulation of Bip. In addition to refining our mechanistic understanding of Sec61 inhibition by mycolactone, our findings thus reveal that Sec61 blockade induces proteostatic stress in the cytosol and the endoplasmic reticulum.
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Affiliation(s)
- Jean-David Morel
- From the ‡Immunobiology of Infection Unit, Institut Pasteur, 75015 Paris, France.,§INSERM, U1221, 75005 Paris, France
| | - Anja O Paatero
- ¶Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Jiajie Wei
- ‖Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Jonathan W Yewdell
- ‖Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Laure Guenin-Macé
- From the ‡Immunobiology of Infection Unit, Institut Pasteur, 75015 Paris, France.,§INSERM, U1221, 75005 Paris, France
| | - Delphi Van Haver
- **VIB-UGent Center for Medical Biotechnology, 9000 Ghent, Belgium.,‡‡VIB Proteomics Core, 9000 Ghent, Belgium.,§§Department of Biochemistry, Ghent University, 9000 Ghent, Belgium
| | - Francis Impens
- **VIB-UGent Center for Medical Biotechnology, 9000 Ghent, Belgium.,‡‡VIB Proteomics Core, 9000 Ghent, Belgium.,§§Department of Biochemistry, Ghent University, 9000 Ghent, Belgium
| | - Natalia Pietrosemoli
- ¶¶Bioinformatics and Biostatistics Hub, Center of Bioinformatics, Biostatistics, and Integrative Biology, Institut Pasteur, Unité de Service et de Recherche 3756 Institut Pasteur CNRS, 75015 Paris, France
| | - Ville O Paavilainen
- ¶Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Caroline Demangel
- From the ‡Immunobiology of Infection Unit, Institut Pasteur, 75015 Paris, France; .,§INSERM, U1221, 75005 Paris, France
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Van Puyenbroeck V, Vermeire K. Inhibitors of protein translocation across membranes of the secretory pathway: novel antimicrobial and anticancer agents. Cell Mol Life Sci 2018; 75:1541-1558. [PMID: 29305616 PMCID: PMC5897483 DOI: 10.1007/s00018-017-2743-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 12/15/2017] [Accepted: 12/27/2017] [Indexed: 12/22/2022]
Abstract
Proteins routed to the secretory pathway start their journey by being transported across biological membranes, such as the endoplasmic reticulum. The essential nature of this protein translocation process has led to the evolution of several factors that specifically target the translocon and block translocation. In this review, various translocation pathways are discussed together with known inhibitors of translocation. Properties of signal peptide-specific systems are highlighted for the development of new therapeutic and antimicrobial applications, as compounds can target signal peptides from either host cells or pathogens and thereby selectively prevent translocation of those specific proteins. Broad inhibition of translocation is also an interesting target for the development of new anticancer drugs because cancer cells heavily depend on efficient protein translocation into the endoplasmic reticulum to support their fast growth.
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Affiliation(s)
- Victor Van Puyenbroeck
- Laboratory of Virology and Chemotherapy, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000, Leuven, Belgium
| | - Kurt Vermeire
- Laboratory of Virology and Chemotherapy, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven - University of Leuven, 3000, Leuven, Belgium.
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69
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Ogbechi J, Hall BS, Sbarrato T, Taunton J, Willis AE, Wek RC, Simmonds RE. Inhibition of Sec61-dependent translocation by mycolactone uncouples the integrated stress response from ER stress, driving cytotoxicity via translational activation of ATF4. Cell Death Dis 2018. [PMID: 29540678 PMCID: PMC5852046 DOI: 10.1038/s41419-018-0427-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mycolactone is the exotoxin virulence factor of Mycobacterium ulcerans that causes the neglected tropical disease Buruli ulcer. We recently showed it to be a broad spectrum inhibitor of Sec61-dependent co-translational translocation of proteins into the endoplasmic reticulum (ER). An outstanding question is the molecular pathway linking this to its known cytotoxicity. We have now used translational profiling to better understand the reprogramming that occurs in cells exposed to mycolactone. Gene ontology identified enrichment in genes involved in cellular response to stress, and apoptosis signalling among those showing enhanced translation. Validation of these results supports a mechanism by which mycolactone activates an integrated stress response meditated by phosphorylation of eIF2α via multiple kinases (PERK, GCN, PKR) without activation of the ER stress sensors IRE1 or ATF6. The response therefore uncouples the integrated stress response from ER stress, and features translational and transcriptional modes of genes expression that feature the key regulatory transcription factor ATF4. Emphasising the importance of this uncoupled response in cytotoxicity, downstream activation of this pathway is abolished in cells expressing mycolactone-resistant Sec61α variants. Using multiple genetic and biochemical approaches, we demonstrate that eIF2α phosphorylation is responsible for mycolactone-dependent translation attenuation, which initially protects cells from cell death. However, chronic activation without stress remediation enhances autophagy and apoptosis of cells by a pathway facilitated by ATF4 and CHOP. Our findings demonstrate that priming events at the ER can result in the sensing of stress within different cellular compartments.
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Affiliation(s)
- Joy Ogbechi
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | - Belinda S Hall
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK
| | | | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Anne E Willis
- MRC Toxicology Unit, Lancaster Rd, Leicester, LE1 9HN, UK
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, 46202-5126, USA
| | - Rachel E Simmonds
- Department of Microbial Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
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Wan X, Serrill JD, Humphreys IR, Tan M, McPhail KL, Ganley IG, Ishmael JE. ATG5 Promotes Death Signaling in Response to the Cyclic Depsipeptides Coibamide A and Apratoxin A. Mar Drugs 2018; 16:E77. [PMID: 29494533 PMCID: PMC5867621 DOI: 10.3390/md16030077] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 02/17/2018] [Accepted: 02/23/2018] [Indexed: 01/08/2023] Open
Abstract
Our understanding of autophagy and lysosomal function has been greatly enhanced by the discovery of natural product structures that can serve as chemical probes to reveal new patterns of signal transduction in cells. Coibamide A is a cytotoxic marine natural product that induces mTOR-independent autophagy as an adaptive stress response that precedes cell death. Autophagy-related (ATG) protein 5 (ATG5) is required for coibamide-induced autophagy but not required for coibamide-induced apoptosis. Using wild-type and autophagy-deficient mouse embryonic fibroblasts (MEFs) we demonstrate that coibamide-induced toxicity is delayed in ATG5-/- cells relative to ATG5+/+ cells. Time-dependent changes in annexin V staining, membrane integrity, metabolic capacity and caspase activation indicated that MEFs with a functional autophagy pathway are more sensitive to coibamide A. This pattern could be distinguished from autophagy modulators that induce acute ER stress (thapsigargin, tunicamycin), ATP depletion (oligomycin A) or mTORC1 inhibition (rapamycin), but was shared with the Sec61 inhibitor apratoxin A. Coibamide- or apratoxin-induced cell stress was further distinguished from the action of thapsigargin by a pattern of early LC3-II accumulation in the absence of CHOP or BiP expression. Time-dependent changes in ATG5-ATG12, PARP1 and caspase-3 expression patterns were consistent with the conversion of ATG5 to a pro-death signal in response to both compounds.
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Affiliation(s)
- Xuemei Wan
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA.
| | - Jeffrey D Serrill
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA.
| | - Ian R Humphreys
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA.
| | - Michelle Tan
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA.
| | - Kerry L McPhail
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA.
| | - Ian G Ganley
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
| | - Jane E Ishmael
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA.
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Membrane perturbing properties of toxin mycolactone from Mycobacterium ulcerans. PLoS Comput Biol 2018; 14:e1005972. [PMID: 29401455 PMCID: PMC5814095 DOI: 10.1371/journal.pcbi.1005972] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 02/15/2018] [Accepted: 01/15/2018] [Indexed: 12/16/2022] Open
Abstract
Mycolactone is the exotoxin produced by Mycobacterium ulcerans and is the virulence factor behind the neglected tropical disease Buruli ulcer. The toxin has a broad spectrum of biological effects within the host organism, stemming from its interaction with at least two molecular targets and the inhibition of protein uptake into the endoplasmic reticulum. Although it has been shown that the toxin can passively permeate into host cells, it is clearly lipophilic. Association with lipid carriers would have substantial implications for the toxin’s distribution within a host organism, delivery to cellular targets, diagnostic susceptibility, and mechanisms of pathogenicity. Yet the toxin’s interactions with, and distribution in, lipids are unknown. Herein we have used coarse-grained molecular dynamics simulations, guided by all-atom simulations, to study the interaction of mycolactone with pure and mixed lipid membranes. Using established techniques, we calculated the toxin’s preferential localization, membrane translocation, and impact on membrane physical and dynamical properties. The computed water-octanol partition coefficient indicates that mycolactone prefers to be in an organic phase rather than in an aqueous environment. Our results show that in a solvated membrane environment the exotoxin mainly localizes in the water-membrane interface, with a preference for the glycerol moiety of lipids, consistent with the reported studies that found it in lipid extracts of the cell. The calculated association constant to the model membrane is similar to the reported association constant for Wiskott-Aldrich syndrome protein. Mycolactone is shown to modify the physical properties of membranes, lowering the transition temperature, compressibility modulus, and critical line tension at which pores can be stabilized. It also shows a tendency to behave as a linactant, a molecule that localizes at the boundary between different fluid lipid domains in membranes and promotes inter-mixing of domains. This property has implications for the toxin’s cellular access, T-cell immunosuppression, and therapeutic potential. Mycolactone is a macrolide exotoxin secreted by Mycobacterium ulcerans, which causes a skin disease called Buruli ulcer, a neglected emerging disease. It is the third most common mycobacterial disease after tuberculosis and leprosy. Studies have shown how mycolactone plays a pivotal role in Buruli ulcer pathogenesis, and identified it as an attractive therapeutic target. This multifunctional cytotoxin exerts multiple local and global responses, including ulcerative, analgesic, and anti-inflammatory effects. Prompted by its lipid-like structure, we used extensive multi-resolution simulations to probe mycolactone’s interactions with model membranes. Our results suggest that mycolactone is sequestered in membranes where it alters several dynamical, physical, and mechanical properties. It also behaves as a linactant, localizing at the interface between lipid domains and decreasing the inter-domain line tension. Our results shed light on how mycolactone permeates host cell membranes and is distributed between lipid and aqueous environments. These findings have significant implications for the toxin’s distribution in the host environment and mechanisms of pathogenicity. Understanding the toxin’s distribution and mechanism of trafficking will have ramifications for targeted diagnostics, therapeutic approaches, and our understanding of Buruli ulcer pathogenesis.
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Nitenberg M, Bénarouche A, Maniti O, Marion E, Marsollier L, Géan J, Dufourc EJ, Cavalier JF, Canaan S, Girard-Egrot AP. The potent effect of mycolactone on lipid membranes. PLoS Pathog 2018; 14:e1006814. [PMID: 29320578 PMCID: PMC5779694 DOI: 10.1371/journal.ppat.1006814] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 01/23/2018] [Accepted: 12/14/2017] [Indexed: 12/15/2022] Open
Abstract
Mycolactone is a lipid-like endotoxin synthesized by an environmental human pathogen, Mycobacterium ulcerans, the causal agent of Buruli ulcer disease. Mycolactone has pleiotropic effects on fundamental cellular processes (cell adhesion, cell death and inflammation). Various cellular targets of mycolactone have been identified and a literature survey revealed that most of these targets are membrane receptors residing in ordered plasma membrane nanodomains, within which their functionalities can be modulated. We investigated the capacity of mycolactone to interact with membranes, to evaluate its effects on membrane lipid organization following its diffusion across the cell membrane. We used Langmuir monolayers as a cell membrane model. Experiments were carried out with a lipid composition chosen to be as similar as possible to that of the plasma membrane. Mycolactone, which has surfactant properties, with an apparent saturation concentration of 1 μM, interacted with the membrane at very low concentrations (60 nM). The interaction of mycolactone with the membrane was mediated by the presence of cholesterol and, like detergents, mycolactone reshaped the membrane. In its monomeric form, this toxin modifies lipid segregation in the monolayer, strongly affecting the formation of ordered microdomains. These findings suggest that mycolactone disturbs lipid organization in the biological membranes it crosses, with potential effects on cell functions and signaling pathways. Microdomain remodeling may therefore underlie molecular events, accounting for the ability of mycolactone to attack multiple targets and providing new insight into a single unifying mechanism underlying the pleiotropic effects of this molecule. This membrane remodeling may act in synergy with the other known effects of mycolactone on its intracellular targets, potentiating these effects.
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Affiliation(s)
- Milène Nitenberg
- Univ. Lyon, Université Lyon 1, CNRS, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, ICBMS—UMR 5246, GEMBAS team, Lyon, France
| | | | - Ofelia Maniti
- Univ. Lyon, Université Lyon 1, CNRS, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, ICBMS—UMR 5246, GEMBAS team, Lyon, France
| | - Estelle Marion
- CRCINA, INSERM, Université de Nantes, Université d'Angers, Angers, France
| | - Laurent Marsollier
- CRCINA, INSERM, Université de Nantes, Université d'Angers, Angers, France
| | - Julie Géan
- Univ. Bordeaux, CNRS, Bordeaux INP, Chemistry and Biology of Membranes and Nano-objects, CBMN UMR 5248, Pessac, France
| | - Erick J. Dufourc
- Univ. Bordeaux, CNRS, Bordeaux INP, Chemistry and Biology of Membranes and Nano-objects, CBMN UMR 5248, Pessac, France
| | - Jean-François Cavalier
- Aix-Marseille Univ, CNRS, EIPL, Marseille, France
- Aix-Marseille Univ, CNRS, LISM, Marseille, France
| | - Stéphane Canaan
- Aix-Marseille Univ, CNRS, EIPL, Marseille, France
- Aix-Marseille Univ, CNRS, LISM, Marseille, France
| | - Agnès P. Girard-Egrot
- Univ. Lyon, Université Lyon 1, CNRS, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, ICBMS—UMR 5246, GEMBAS team, Lyon, France
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73
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Yotsu RR, Suzuki K, Simmonds RE, Bedimo R, Ablordey A, Yeboah-Manu D, Phillips R, Asiedu K. Buruli Ulcer: a Review of the Current Knowledge. CURRENT TROPICAL MEDICINE REPORTS 2018; 5:247-256. [PMID: 30460172 PMCID: PMC6223704 DOI: 10.1007/s40475-018-0166-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE OF THE REVIEW Buruli ulcer (BU) is a necrotizing and disabling cutaneous disease caused by Mycobacterium ulcerans, one of the skin-related neglected tropical diseases (skin NTDs). This article aims to review the current knowledge of this disease and challenges ahead. RECENT FINDINGS Around 60,000 cases of BU have been reported from over 33 countries between 2002 and 2017. Encouraging findings for development of point-of-care tests for BU are being made, and its treatment is currently in the transition period from rifampicin plus streptomycin (injection) to all-oral regimen. A major recent advance in our understanding of its pathogenesis has been agreement on the mechanism of action of the major virulence toxin mycolactone in host cells, targeting the Sec61 translocon during a major step in protein biogenesis. SUMMARY BU is distributed mainly in West Africa, but cases are also found in other parts of the world. We may be underestimating its true disease burden, due to the limited awareness of this disease. More awareness and more understanding of BU will surely contribute in enhancing our fight against this skin NTD.
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Affiliation(s)
- Rie R. Yotsu
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
- Department of Dermatology, National Center for Global Health and Medicine, Tokyo, Japan
- Department of Dermatology, National Suruga Sanatorium, Shizuoka, Japan
| | - Koichi Suzuki
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo, Japan
| | - Rachel E. Simmonds
- Department of Microbial Sciences, School of Bioscience and Medicine, University of Surrey, Surrey, UK
| | - Roger Bedimo
- Department of Medicine, VA North Texas Healthcare System, Dallas, TX USA
- Division of Infectious Diseases, University of Texas Dallas Southwestern, Dallas, TX USA
| | - Anthony Ablordey
- Department of Bacteriology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Dorothy Yeboah-Manu
- Department of Bacteriology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Richard Phillips
- Kumansi Centre for Collaborative Research in Tropical Medicine, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Kingsley Asiedu
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
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Buruli Ulcer, a Prototype for Ecosystem-Related Infection, Caused by Mycobacterium ulcerans. Clin Microbiol Rev 2017; 31:31/1/e00045-17. [PMID: 29237707 DOI: 10.1128/cmr.00045-17] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Buruli ulcer is a noncontagious disabling cutaneous and subcutaneous mycobacteriosis reported by 33 countries in Africa, Asia, Oceania, and South America. The causative agent, Mycobacterium ulcerans, derives from Mycobacterium marinum by genomic reduction and acquisition of a plasmid-borne, nonribosomal cytotoxin mycolactone, the major virulence factor. M. ulcerans-specific sequences have been readily detected in aquatic environments in food chains involving small mammals. Skin contamination combined with any type of puncture, including insect bites, is the most plausible route of transmission, and skin temperature of <30°C significantly correlates with the topography of lesions. After 30 years of emergence and increasing prevalence between 1970 and 2010, mainly in Africa, factors related to ongoing decreasing prevalence in the same countries remain unexplained. Rapid diagnosis, including laboratory confirmation at the point of care, is mandatory in order to reduce delays in effective treatment. Parenteral and potentially toxic streptomycin-rifampin is to be replaced by oral clarithromycin or fluoroquinolone combined with rifampin. In the absence of proven effective primary prevention, avoiding skin contamination by means of clothing can be implemented in areas of endemicity. Buruli ulcer is a prototype of ecosystem pathology, illustrating the impact of human activities on the environment as a source for emerging tropical infectious diseases.
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75
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Isaac C, Mauborgne A, Grimaldi A, Ade K, Pohl M, Limatola C, Boucher Y, Demangel C, Guenin-Macé L. Mycolactone displays anti-inflammatory effects on the nervous system. PLoS Negl Trop Dis 2017; 11:e0006058. [PMID: 29149212 PMCID: PMC5693295 DOI: 10.1371/journal.pntd.0006058] [Citation(s) in RCA: 14] [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: 06/01/2017] [Accepted: 10/20/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Mycolactone is a macrolide produced by the skin pathogen Mycobacterium ulcerans, with cytotoxic, analgesic and immunomodulatory properties. The latter were recently shown to result from mycolactone blocking the Sec61-dependent production of pro-inflammatory mediators by immune cells. Here we investigated whether mycolactone similarly affects the inflammatory responses of the nervous cell subsets involved in pain perception, transmission and maintenance. We also investigated the effects of mycolactone on the neuroinflammation that is associated with chronic pain in vivo. METHODOLOGY/ PRINCIPLE FINDINGS Sensory neurons, Schwann cells and microglia were isolated from mice for ex vivo assessment of mycolactone cytotoxicity and immunomodulatory activity by measuring the production of proalgesic cytokines and chemokines. In all cell types studied, prolonged (>48h) exposure to mycolactone induced significant cell death at concentrations >10 ng/ml. Within the first 24h treatment, nanomolar concentrations of mycolactone efficiently suppressed the cell production of pro-inflammatory mediators, without affecting their viability. Notably, mycolactone also prevented the pro-inflammatory polarization of cortical microglia. Since these cells critically contribute to neuroinflammation, we next tested if mycolactone impacts this pathogenic process in vivo. We used a rat model of neuropathic pain induced by chronic constriction of the sciatic nerve. Here, mycolactone was injected daily for 3 days in the spinal canal, to ensure its proper delivery to spinal cord. While this treatment failed to prevent injury-induced neuroinflammation, it decreased significantly the local production of inflammatory cytokines without inducing detectable cytotoxicity. CONCLUSION/ SIGNIFICANCE The present study provides in vitro and in vivo evidence that mycolactone suppresses the inflammatory responses of sensory neurons, Schwann cells and microglia, without affecting the cell viability. Together with previous studies using peripheral blood leukocytes, our work implies that mycolactone-mediated analgesia may, at least partially, be explained by its anti-inflammatory properties.
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Affiliation(s)
- Caroline Isaac
- Institut Pasteur, Unité d’Immunobiologie de l’Infection, Paris, France
- INSERM U1221, Paris, France
| | - Annie Mauborgne
- Centre de Psychiatrie et Neurosciences, Inserm U894, Paris, France
| | - Alfonso Grimaldi
- Pasteur Institute Rome, Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Kemy Ade
- Institut Pasteur, Unité d’Immunobiologie de l’Infection, Paris, France
- INSERM U1221, Paris, France
| | - Michel Pohl
- Centre de Psychiatrie et Neurosciences, Inserm U894, Paris, France
| | - Cristina Limatola
- Pasteur Institute Rome, Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
- IRCCS Neuromed, Pozzilli, Italy
| | - Yves Boucher
- Centre de Psychiatrie et Neurosciences, Inserm U894, Paris, France
- Groupe Hospitalier Pitié Salpétrière, UFR Odontologie Université Paris Diderot, Paris, France
| | - Caroline Demangel
- Institut Pasteur, Unité d’Immunobiologie de l’Infection, Paris, France
- INSERM U1221, Paris, France
| | - Laure Guenin-Macé
- Institut Pasteur, Unité d’Immunobiologie de l’Infection, Paris, France
- INSERM U1221, Paris, France
- * E-mail:
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76
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Paatero AO, Kellosalo J, Dunyak BM, Almaliti J, Gestwicki JE, Gerwick WH, Taunton J, Paavilainen VO. Apratoxin Kills Cells by Direct Blockade of the Sec61 Protein Translocation Channel. Cell Chem Biol 2017; 23:561-566. [PMID: 27203376 DOI: 10.1016/j.chembiol.2016.04.008] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 04/04/2016] [Accepted: 04/07/2016] [Indexed: 12/17/2022]
Abstract
Apratoxin A is a cytotoxic natural product that prevents the biogenesis of secretory and membrane proteins. Biochemically, apratoxin A inhibits cotranslational translocation into the ER, but its cellular target and mechanism of action have remained controversial. Here, we demonstrate that apratoxin A prevents protein translocation by directly targeting Sec61α, the central subunit of the protein translocation channel. Mutagenesis and competitive photo-crosslinking studies indicate that apratoxin A binds to the Sec61 lateral gate in a manner that differs from cotransin, a substrate-selective Sec61 inhibitor. In contrast to cotransin, apratoxin A does not exhibit a substrate-selective inhibitory mechanism, but blocks ER translocation of all tested Sec61 clients with similar potency. Our results suggest that multiple structurally unrelated natural products have evolved to target overlapping but non-identical binding sites on Sec61, thereby producing distinct biological outcomes.
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Affiliation(s)
- Anja O Paatero
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, Biocenter 3, Helsinki 00014, Finland
| | - Juho Kellosalo
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, Biocenter 3, Helsinki 00014, Finland
| | - Bryan M Dunyak
- Department of Pharmaceutical Chemistry, Institute for Neurodegenerative Disease, University of California at San Francisco, San Francisco, CA 94038, USA
| | - Jehad Almaliti
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Jason E Gestwicki
- Department of Pharmaceutical Chemistry, Institute for Neurodegenerative Disease, University of California at San Francisco, San Francisco, CA 94038, USA
| | - William H Gerwick
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
| | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Ville O Paavilainen
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, Biocenter 3, Helsinki 00014, Finland.
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77
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Lang S, Pfeffer S, Lee PH, Cavalié A, Helms V, Förster F, Zimmermann R. An Update on Sec61 Channel Functions, Mechanisms, and Related Diseases. Front Physiol 2017; 8:887. [PMID: 29163222 PMCID: PMC5672155 DOI: 10.3389/fphys.2017.00887] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/19/2017] [Indexed: 12/18/2022] Open
Abstract
The membrane of the endoplasmic reticulum (ER) of nucleated human cells harbors the protein translocon, which facilitates membrane integration or translocation of almost every newly synthesized polypeptide targeted to organelles of the endo- and exocytotic pathway. The translocon comprises the polypeptide-conducting Sec61 channel and several additional proteins and complexes that are permanently or transiently associated with the heterotrimeric Sec61 complex. This ensemble of proteins facilitates ER targeting of precursor polypeptides, modification of precursor polypeptides in transit through the Sec61 complex, and Sec61 channel gating, i.e., dynamic regulation of the pore forming subunit to mediate precursor transport and calcium efflux. Recently, cryoelectron tomography of translocons in native ER membrane vesicles, derived from human cell lines or patient fibroblasts, and even intact cells has given unprecedented insights into the architecture and dynamics of the native translocon and the Sec61 channel. These structural data are discussed in light of different Sec61 channel activities including ribosome receptor function, membrane insertion, and translocation of newly synthesized polypeptides as well as the putative physiological roles of the Sec61 channel as a passive ER calcium leak channel. Furthermore, the structural insights into the Sec61 channel are incorporated into an overview and update on Sec61 channel-related diseases—the Sec61 channelopathies—and novel therapeutic concepts for their treatment.
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Affiliation(s)
- Sven Lang
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
| | - Stefan Pfeffer
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Po-Hsien Lee
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Adolfo Cavalié
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, Homburg, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Friedrich Förster
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
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78
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Gehringer M, Altmann KH. The chemistry and biology of mycolactones. Beilstein J Org Chem 2017; 13:1596-1660. [PMID: 28904608 PMCID: PMC5564285 DOI: 10.3762/bjoc.13.159] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/21/2017] [Indexed: 12/21/2022] Open
Abstract
Mycolactones are a group of macrolides excreted by the human pathogen Mycobacterium ulcerans, which exhibit cytotoxic, immunosuppressive and analgesic properties. As the virulence factor of M. ulcerans, mycolactones are central to the pathogenesis of the neglected disease Buruli ulcer, a chronic and debilitating medical condition characterized by necrotic skin ulcers. Due to their complex structure and fascinating biology, mycolactones have inspired various total synthesis endeavors and structure-activity relationship studies. Although this review intends to cover all synthesis efforts in the field, special emphasis is given to the comparison of conceptually different approaches and to the discussion of more recent contributions. Furthermore, a detailed discussion of molecular targets and structure-activity relationships is provided.
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Affiliation(s)
- Matthias Gehringer
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
| | - Karl-Heinz Altmann
- Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, ETH Zürich, Vladimir-Prelog-Weg 4, 8093 Zürich, Switzerland
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79
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En J, Kitamoto S, Kawashima A, Yonezawa S, Kishi Y, Ishii N, Goto M. Mycolactone cytotoxicity in Schwann cells could explain nerve damage in Buruli ulcer. PLoS Negl Trop Dis 2017; 11:e0005834. [PMID: 28783752 PMCID: PMC5559071 DOI: 10.1371/journal.pntd.0005834] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 08/16/2017] [Accepted: 07/25/2017] [Indexed: 01/11/2023] Open
Abstract
Buruli ulcer is a chronic painless skin disease caused by Mycobacterium ulcerans. The local nerve damage induced by M. ulcerans invasion is similar to the nerve damage evoked by the injection of mycolactone in a Buruli ulcer mouse model. In order to elucidate the mechanism of this nerve damage, we tested and compared the cytotoxic effect of synthetic mycolactone A/B on cultured Schwann cells, fibroblasts and macrophages. Mycolactone induced much higher cell death and apoptosis in Schwann cell line SW10 than in fibroblast line L929. These results suggest that mycolactone is a key substance in the production of nerve damage of Buruli ulcer. Buruli ulcer is a chronic skin disease caused by Mycobacterium ulcerans, and the disease is characterized by the painless nature of its lesion. Similar to leprosy, loss of pain often hinders the patients from taking proper medical care, resulting in gross deformities. A toxic lipid mycolactone produced from Mycobacterium ulcerans was thought to block the sensory system of the lesion, either by direct cellular damage (cytotoxicity) to the regional nerve tissue, or by a more sophisticated, non-toxic paralyzing mechanism. In the peripheral nerve, Schwann cells nourish axons and accelerate nerve conduction. In this study, we have compared the cytotoxic potential of mycolactone on cultured Schwann cells and that on fibroblasts, and found that mycolactone A/B induced much higher cell death and apoptosis in Schwann cell line SW10 than in fibroblast line L929. These results support the cytotoxic theory and suggest that mycolactone is a key substance in the production of nerve damage of Buruli ulcer.
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Affiliation(s)
- Junichiro En
- Department of Pathology, Kagoshima University, Kagoshima, Japan
- National Sanatorium Hoshizuka-Keiaien, Kanoya, Kagoshima, Japan
- International University of Health and Welfare, Narita, Chiba, Japan
- * E-mail:
| | - Sho Kitamoto
- Department of Pathology, Kagoshima University, Kagoshima, Japan
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Akira Kawashima
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Itabashi, Tokyo, Japan
| | - Suguru Yonezawa
- Department of Pathology, Kagoshima University, Kagoshima, Japan
| | - Yoshito Kishi
- Department of Chemistry and Chemical Biology, Harvard University, Boston, Massachusetts, United States of America
| | - Norihisa Ishii
- Leprosy Research Center, National Institute of Infectious Diseases, Higashimurayama, Tokyo, Japan
| | - Masamichi Goto
- Department of Pathology, Kagoshima University, Kagoshima, Japan
- National Sanatorium Hoshizuka-Keiaien, Kanoya, Kagoshima, Japan
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80
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A Bacterial Toxin with Analgesic Properties: Hyperpolarization of DRG Neurons by Mycolactone. Toxins (Basel) 2017; 9:toxins9070227. [PMID: 28718822 PMCID: PMC5535174 DOI: 10.3390/toxins9070227] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 07/10/2017] [Accepted: 07/13/2017] [Indexed: 12/20/2022] Open
Abstract
Mycolactone, a polyketide molecule produced by Mycobacterium ulcerans, is the etiological agent of Buruli ulcer. This lipid toxin is endowed with pleiotropic effects, presents cytotoxic effects at high doses, and notably plays a pivotal role in host response upon colonization by the bacillus. Most remarkably, mycolactone displays intriguing analgesic capabilities: the toxin suppresses or alleviates the pain of the skin lesions it inflicts. We demonstrated that the analgesic capability of mycolactone was not attributable to nerve damage, but instead resulted from the triggering of a cellular pathway targeting AT₂ receptors (angiotensin II type 2 receptors; AT₂R), and leading to potassium-dependent hyperpolarization. This demonstration paves the way to new nature-inspired analgesic protocols. In this direction, we assess here the hyperpolarizing properties of mycolactone on nociceptive neurons. We developed a dedicated medium-throughput assay based on membrane potential changes, and visualized by confocal microscopy of bis-oxonol-loaded Dorsal Root Ganglion (DRG) neurons. We demonstrate that mycolactone at non-cytotoxic doses triggers the hyperpolarization of DRG neurons through AT₂R, with this action being not affected by known ligands of AT₂R. This result points towards novel AT₂R-dependent signaling pathways in DRG neurons underlying the analgesic effect of mycolactone, with the perspective for the development of new types of nature-inspired analgesics.
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81
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Sec61 blockade by mycolactone inhibits antigen cross-presentation independently of endosome-to-cytosol export. Proc Natl Acad Sci U S A 2017; 114:E5910-E5919. [PMID: 28679634 DOI: 10.1073/pnas.1705242114] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although antigen cross-presentation in dendritic cells (DCs) is critical to the initiation of most cytotoxic immune responses, the intracellular mechanisms and traffic pathways involved are still unclear. One of the most critical steps in this process, the export of internalized antigen to the cytosol, has been suggested to be mediated by Sec61. Sec61 is the channel that translocates signal peptide-bearing nascent polypeptides into the endoplasmic reticulum (ER), and it was also proposed to mediate protein retrotranslocation during ER-associated degradation (a process called ERAD). Here, we used a newly identified Sec61 blocker, mycolactone, to analyze Sec61's contribution to antigen cross-presentation, ERAD, and transport of internalized antigens into the cytosol. As shown previously in other cell types, mycolactone prevented protein import into the ER of DCs. Mycolactone-mediated Sec61 blockade also potently suppressed both antigen cross-presentation and direct presentation of synthetic peptides to CD8+ T cells. In contrast, it did not affect protein export from the ER lumen or from endosomes into the cytosol, suggesting that the inhibition of cross-presentation was not related to either of these trafficking pathways. Proteomic profiling of mycolactone-exposed DCs showed that expression of mediators of antigen presentation, including MHC class I and β2 microglobulin, were highly susceptible to mycolactone treatment, indicating that Sec61 blockade affects antigen cross-presentation indirectly. Together, our data suggest that the defective translocation and subsequent degradation of Sec61 substrates is the cause of altered antigen cross-presentation in Sec61-blocked DCs.
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82
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Monel B, Compton AA, Bruel T, Amraoui S, Burlaud-Gaillard J, Roy N, Guivel-Benhassine F, Porrot F, Génin P, Meertens L, Sinigaglia L, Jouvenet N, Weil R, Casartelli N, Demangel C, Simon-Lorière E, Moris A, Roingeard P, Amara A, Schwartz O. Zika virus induces massive cytoplasmic vacuolization and paraptosis-like death in infected cells. EMBO J 2017; 36:1653-1668. [PMID: 28473450 PMCID: PMC5470047 DOI: 10.15252/embj.201695597] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 03/23/2017] [Accepted: 03/28/2017] [Indexed: 12/15/2022] Open
Abstract
The cytopathic effects of Zika virus (ZIKV) are poorly characterized. Innate immunity controls ZIKV infection and disease in most infected patients through mechanisms that remain to be understood. Here, we studied the morphological cellular changes induced by ZIKV and addressed the role of interferon-induced transmembrane proteins (IFITM), a family of broad-spectrum antiviral factors, during viral replication. We report that ZIKV induces massive vacuolization followed by "implosive" cell death in human epithelial cells, primary skin fibroblasts and astrocytes, a phenomenon which is exacerbated when IFITM3 levels are low. It is reminiscent of paraptosis, a caspase-independent, non-apoptotic form of cell death associated with the formation of large cytoplasmic vacuoles. We further show that ZIKV-induced vacuoles are derived from the endoplasmic reticulum (ER) and dependent on the PI3K/Akt signaling axis. Inhibiting the Sec61 ER translocon in ZIKV-infected cells blocked vacuole formation and viral production. Our results provide mechanistic insight behind the ZIKV-induced cytopathic effect and indicate that IFITM3, by acting as a gatekeeper for incoming virus, restricts virus takeover of the ER and subsequent cell death.
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Affiliation(s)
| | | | | | - Sonia Amraoui
- Virus & Immunity Unit, Institut Pasteur, Paris, France
| | - Julien Burlaud-Gaillard
- INSERM U966 & Platefome IBiSA de Microscopie Electronique, Université François Rabelais and CHRU de Tours, Paris, France
| | - Nicolas Roy
- Virus & Immunity Unit, Institut Pasteur, Paris, France
| | | | | | - Pierre Génin
- Signaling and Pathogenesis Laboratory and CNRS UMR3691, Institut Pasteur, Paris, France
| | - Laurent Meertens
- INSERM U944, CNRS 7212 Laboratoire de Pathologie et Virologie Moléculaire, Institut Universitaire d'Hématologie, Hôpital Saint-Louis, Paris, France
| | - Laura Sinigaglia
- Viral Genomics and Vaccination Unit, Institut Pasteur, Paris, France
- UMR CNRS 3569, Paris, France
| | - Nolwenn Jouvenet
- Viral Genomics and Vaccination Unit, Institut Pasteur, Paris, France
- UMR CNRS 3569, Paris, France
| | - Robert Weil
- Signaling and Pathogenesis Laboratory and CNRS UMR3691, Institut Pasteur, Paris, France
| | | | | | - Etienne Simon-Lorière
- Institut Pasteur, Unité de Génétique Fonctionnelle des Maladies Infectieuses, Paris, France
- CNRS URA 3012, Paris, France
| | - Arnaud Moris
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U1135, CNRS ERL 8255, Center for Immunology and Microbial Infections - CIMI-Paris, Paris, France
| | - Philippe Roingeard
- INSERM U966 & Platefome IBiSA de Microscopie Electronique, Université François Rabelais and CHRU de Tours, Paris, France
| | - Ali Amara
- INSERM U944, CNRS 7212 Laboratoire de Pathologie et Virologie Moléculaire, Institut Universitaire d'Hématologie, Hôpital Saint-Louis, Paris, France
| | - Olivier Schwartz
- Virus & Immunity Unit, Institut Pasteur, Paris, France
- UMR CNRS 3569, Paris, France
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Bieri R, Scherr N, Ruf MT, Dangy JP, Gersbach P, Gehringer M, Altmann KH, Pluschke G. The Macrolide Toxin Mycolactone Promotes Bim-Dependent Apoptosis in Buruli Ulcer through Inhibition of mTOR. ACS Chem Biol 2017; 12:1297-1307. [PMID: 28294596 DOI: 10.1021/acschembio.7b00053] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mycolactone, the macrolide exotoxin produced by Mycobacterium ulcerans, is central to the pathogenesis of the chronic necrotizing skin disease Buruli ulcer (BU). Here we show that mycolactone acts as an inhibitor of the mechanistic Target of Rapamycin (mTOR) signaling pathway by interfering with the assembly of the two distinct mTOR protein complexes mTORC1 and mTORC2, which regulate different cellular processes. Inhibition of the assembly of the rictor containing mTORC2 complex by mycolactone prevents phosphorylation of the serine/threonine protein kinase Akt. The associated inactivation of Akt leads to the dephosphorylation and activation of the Akt-targeted transcription factor FoxO3. Subsequent up-regulation of the FoxO3 target gene BCL2L11 (Bim) increases expression of the pro-apoptotic regulator Bim, driving mycolactone treated mammalian cells into apoptosis. The central role of Bim-dependent apoptosis in BU pathogenesis deduced from our experiments with cultured mammalian cells was further verified in an experimental M. ulcerans infection model. As predicted by the model, M. ulcerans infected Bim knockout mice did not develop necrotic BU lesions with large clusters of extracellular bacteria, but were able to contain the mycobacterial multiplication. Our findings provide a new coherent and comprehensive concept of BU pathogenesis.
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Affiliation(s)
- Raphael Bieri
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz
1, 4003 Basel, Switzerland
| | - Nicole Scherr
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz
1, 4003 Basel, Switzerland
| | - Marie-Thérèse Ruf
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz
1, 4003 Basel, Switzerland
| | - Jean-Pierre Dangy
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz
1, 4003 Basel, Switzerland
| | - Philipp Gersbach
- Department
of Chemistry and Applied Biosciences, Institute of Pharmaceutical
Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - Matthias Gehringer
- Department
of Chemistry and Applied Biosciences, Institute of Pharmaceutical
Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - Karl-Heinz Altmann
- Department
of Chemistry and Applied Biosciences, Institute of Pharmaceutical
Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - Gerd Pluschke
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, Petersplatz
1, 4003 Basel, Switzerland
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84
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McKenna M, Simmonds RE, High S. Mycolactone reveals the substrate-driven complexity of Sec61-dependent transmembrane protein biogenesis. J Cell Sci 2017; 130:1307-1320. [PMID: 28219954 PMCID: PMC5399781 DOI: 10.1242/jcs.198655] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 02/02/2017] [Indexed: 12/22/2022] Open
Abstract
Mycolactone is the exotoxin virulence factor produced by Mycobacterium ulcerans, the pathogen responsible for Buruli ulcer. The skin lesions and immunosuppression that are characteristic of this disease result from the action of mycolactone, which targets the Sec61 complex and inhibits the co-translational translocation of secretory proteins into the endoplasmic reticulum. In this study, we investigate the effect of mycolactone on the Sec61-dependent biogenesis of different classes of transmembrane protein (TMP). Our data suggest that the effect of mycolactone on TMP biogenesis depends on how the nascent chain initially engages the Sec61 complex. For example, the translocation of TMP lumenal domains driven by an N-terminal cleavable signal sequence is efficiently inhibited by mycolactone. In contrast, the effect of mycolactone on protein translocation that is driven solely by a non-cleavable signal anchor/transmembrane domain depends on which flanking region is translocated. For example, while translocation of the region N-terminal to a signal anchor/transmembrane domain is refractive to mycolactone, C-terminal translocation is efficiently inhibited. Our findings highlight the diversity of Sec61-dependent translocation and provide a molecular basis for understanding the effect of mycolactone on the biogenesis of different TMPs. Highlighted Article: The exotoxin mycolactone interferes with the biogenesis of the majority of transmembrane proteins and its actions highlight differences in how distinct classes of these proteins initially engage the Sec61 translocon.
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Affiliation(s)
- Michael McKenna
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Michael Smith Building, Manchester M13 9PT, UK
| | - Rachel E Simmonds
- Department of Microbial Sciences, School of Bioscience and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Stephen High
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Michael Smith Building, Manchester M13 9PT, UK
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85
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Baron L, Paatero AO, Morel JD, Impens F, Guenin-Macé L, Saint-Auret S, Blanchard N, Dillmann R, Niang F, Pellegrini S, Taunton J, Paavilainen VO, Demangel C. Mycolactone subverts immunity by selectively blocking the Sec61 translocon. J Exp Med 2016; 213:2885-2896. [PMID: 27821549 PMCID: PMC5154940 DOI: 10.1084/jem.20160662] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/26/2016] [Accepted: 10/17/2016] [Indexed: 12/29/2022] Open
Abstract
Mycolactone, an immunosuppressive macrolide released by the human pathogen Mycobacterium ulcerans, was previously shown to impair Sec61-dependent protein translocation, but the underlying molecular mechanism was not identified. In this study, we show that mycolactone directly targets the α subunit of the Sec61 translocon to block the production of secreted and integral membrane proteins with high potency. We identify a single-amino acid mutation conferring resistance to mycolactone, which localizes its interaction site near the lumenal plug of Sec61α. Quantitative proteomics reveals that during T cell activation, mycolactone-mediated Sec61 blockade affects a selective subset of secretory proteins including key signal-transmitting receptors and adhesion molecules. Expression of mutant Sec61α in mycolactone-treated T cells rescued their homing potential and effector functions. Furthermore, when expressed in macrophages, the mycolactone-resistant mutant restored IFN-γ receptor-mediated antimicrobial responses. Thus, our data provide definitive genetic evidence that Sec61 is the host receptor mediating the diverse immunomodulatory effects of mycolactone and identify Sec61 as a novel regulator of immune cell functions.
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Affiliation(s)
- Ludivine Baron
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | | | - Jean-David Morel
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Francis Impens
- Unité des Interactions Bactéries-Cellules, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U604, Institut National de la Recherche Agronomique, Unité sous-contrat 2020, 75015 Paris, France
| | - Laure Guenin-Macé
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Sarah Saint-Auret
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7509, École européenne de Chimie, Polymères et Matériaux, Université de Strasbourg, 67087 Strasbourg, France
| | - Nicolas Blanchard
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7509, École européenne de Chimie, Polymères et Matériaux, Université de Strasbourg, 67087 Strasbourg, France
| | - Rabea Dillmann
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Fatoumata Niang
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Sandra Pellegrini
- Unité de Signalisation des Cytokines, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
| | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158
| | | | - Caroline Demangel
- Unité d’Immunobiologie de l’Infection, Institut Pasteur, Institut National de la Santé et de la Recherche Médicale U1221, 75015 Paris, France
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86
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Sarfo FS, Phillips R, Wansbrough-Jones M, Simmonds RE. Recent advances: role of mycolactone in the pathogenesis and monitoring of Mycobacterium ulcerans infection/Buruli ulcer disease. Cell Microbiol 2016; 18:17-29. [PMID: 26572803 PMCID: PMC4705457 DOI: 10.1111/cmi.12547] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 11/10/2015] [Accepted: 11/13/2015] [Indexed: 02/03/2023]
Abstract
Infection of subcutaneous tissue with Mycobacterium ulcerans can lead to chronic skin ulceration known as Buruli ulcer. The pathogenesis of this neglected tropical disease is dependent on a lipid‐like toxin, mycolactone, which diffuses through tissue away from the infecting organisms. Since its identification in 1999, this molecule has been intensely studied to elucidate its cytotoxic and immunosuppressive properties. Two recent major advances identifying the underlying molecular targets for mycolactone have been described. First, it can target scaffolding proteins (such as Wiskott Aldrich Syndrome Protein), which control actin dynamics in adherent cells and therefore lead to detachment and cell death by anoikis. Second, it prevents the co‐translational translocation (and therefore production) of many proteins that pass through the endoplasmic reticulum for secretion or placement in cell membranes. These pleiotropic effects underpin the range of cell‐specific functional defects in immune and other cells that contact mycolactone during infection. The dose and duration of mycolactone exposure for these different cells explains tissue necrosis and the paucity of immune cells in the ulcers. This review discusses recent advances in the field, revisits older findings in this context and highlights current developments in structure‐function studies as well as methodology that make mycolactone a promising diagnostic biomarker.
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Affiliation(s)
- Fred Stephen Sarfo
- Department of Medicine, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
| | - Richard Phillips
- Department of Medicine, Kwame Nkrumah University of Science & Technology, Kumasi, Ghana
| | - Mark Wansbrough-Jones
- Division of Cellular and Molecular Medicine, St George's, University of London, London, UK
| | - Rachel E Simmonds
- School of Biosciences and Medicine, University of Surrey, Guildford, UK
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87
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Anand U, Sinisi M, Fox M, MacQuillan A, Quick T, Korchev Y, Bountra C, McCarthy T, Anand P. Mycolactone-mediated neurite degeneration and functional effects in cultured human and rat DRG neurons: Mechanisms underlying hypoalgesia in Buruli ulcer. Mol Pain 2016; 12:12/0/1744806916654144. [PMID: 27325560 PMCID: PMC4956182 DOI: 10.1177/1744806916654144] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 05/16/2016] [Indexed: 01/08/2023] Open
Abstract
Background Mycolactone is a polyketide toxin secreted by the mycobacterium Mycobacterium ulcerans, responsible for the extensive hypoalgesic skin lesions characteristic of patients with Buruli ulcer. A recent pre-clinical study proposed that mycolactone may produce analgesia via activation of the angiotensin II type 2 receptor (AT2R). In contrast, AT2R antagonist EMA401 has shown analgesic efficacy in animal models and clinical trials for neuropathic pain. We therefore investigated the morphological and functional effects of mycolactone in cultured human and rat dorsal root ganglia (DRG) neurons and the role of AT2R using EMA401. Primary sensory neurons were prepared from avulsed cervical human DRG and rat DRG; 24 h after plating, neurons were incubated for 24 to 96 h with synthetic mycolactone A/B, followed by immunostaining with antibodies to PGP9.5, Gap43, β tubulin, or Mitotracker dye staining. Acute functional effects were examined by measuring capsaicin responses with calcium imaging in DRG neuronal cultures treated with mycolactone. Results Morphological effects: Mycolactone-treated cultures showed dramatically reduced numbers of surviving neurons and non-neuronal cells, reduced Gap43 and β tubulin expression, degenerating neurites and reduced cell body diameter, compared with controls. Dose-related reduction of neurite length was observed in mycolactone-treated cultures. Mitochondria were distributed throughout the length of neurites and soma of control neurons, but clustered in the neurites and soma of mycolactone-treated neurons. Functional effects: Mycolactone-treated human and rat DRG neurons showed dose-related inhibition of capsaicin responses, which were reversed by calcineurin inhibitor cyclosporine and phosphodiesterase inhibitor 3-isobutyl-1-Methylxanthine, indicating involvement of cAMP/ATP reduction. The morphological and functional effects of mycolactone were not altered by Angiotensin II or AT2R antagonist EMA401. Conclusion Mycolactone induces toxic effects in DRG neurons, leading to impaired nociceptor function, neurite degeneration, and cell death, resembling the cutaneous hypoalgesia and nerve damage in individuals with M. Ulcerans infection.
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Affiliation(s)
- U Anand
- Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - M Sinisi
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - M Fox
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - A MacQuillan
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - T Quick
- Peripheral Nerve Injury Unit, Royal National Orthopaedic Hospital, Middlesex, UK
| | - Y Korchev
- Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - C Bountra
- University of Oxford Structural Genomics Consortium, Headington, Oxford, UK
| | - T McCarthy
- Spinifex Pharmaceuticals Pty Ltd, St. Preston, VIC, Australia
| | - P Anand
- Department of Medicine, Imperial College London, Hammersmith Hospital, London, UK
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88
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Capela C, Dossou AD, Silva-Gomes R, Sopoh GE, Makoutode M, Menino JF, Fraga AG, Cunha C, Carvalho A, Rodrigues F, Pedrosa J. Genetic Variation in Autophagy-Related Genes Influences the Risk and Phenotype of Buruli Ulcer. PLoS Negl Trop Dis 2016; 10:e0004671. [PMID: 27128681 PMCID: PMC4851401 DOI: 10.1371/journal.pntd.0004671] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/06/2016] [Indexed: 01/05/2023] Open
Abstract
Introduction Buruli ulcer (BU) is a severe necrotizing human skin disease caused by Mycobacterium ulcerans. Clinically, presentation is a sum of these diverse pathogenic hits subjected to critical immune-regulatory mechanisms. Among them, autophagy has been demonstrated as a cellular process of critical importance. Since microtubules and dynein are affected by mycolactone, the critical pathogenic exotoxin produced by M. ulcerans, cytoskeleton-related changes might potentially impair the autophagic process and impact the risk and progression of infection. Objective Genetic variants in the autophagy-related genes NOD2, PARK2 and ATG16L1 has been associated with susceptibility to mycobacterial diseases. Here, we investigated their association with BU risk, its severe phenotypes and its progression to an ulcerative form. Methods Genetic variants were genotyped using KASPar chemistry in 208 BU patients (70.2% with an ulcerative form and 28% in severe WHO category 3 phenotype) and 300 healthy endemic controls. Results The rs1333955 SNP in PARK2 was significantly associated with increased susceptibility to BU [odds ratio (OR), 1.43; P = 0.05]. In addition, both the rs9302752 and rs2066842 SNPs in NOD2 gee significantly increased the predisposition of patients to develop category 3 (OR, 2.23; P = 0.02; and OR 12.7; P = 0.03, respectively, whereas the rs2241880 SNP in ATG16L1 was found to significantly protect patients from presenting the ulcer phenotype (OR, 0.35; P = 0.02). Conclusion Our findings indicate that specific genetic variants in autophagy-related genes influence susceptibility to the development of BU and its progression to severe phenotypes. Buruli ulcer (BU) is a neglected tropical disease caused by Mycobacterium ulcerans. Because the exact trigger is still under investigation, current treatment options rely mostly on the surgical excision of the affected site. There is therefore a pressing demand for improved risk prediction and tailored treatment as well as for new drug targets. By resorting to the largest case-control study reported to date, we show that genetic variation in the autophagy-related genes NOD2, PARK2 and ATG16L1 influence the risk and course of BU disease. Thus, our results provide crucial insights into the role of autophagy in the pathogenesis of BU.
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Affiliation(s)
- Carlos Capela
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | | | - Rita Silva-Gomes
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Ghislain Emmanuel Sopoh
- Buruli Ulcer Treatment Center of Allada, Allada, Benin
- Regional Institute for Public Health, Ouidah, Benin
| | | | - João Filipe Menino
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Alexandra Gabriel Fraga
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Cristina Cunha
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Agostinho Carvalho
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Fernando Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Jorge Pedrosa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
- ICVS/3B’s - PT Government Associate Laboratory, Braga/Guimarães, Portugal
- * E-mail:
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89
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Guenin-Macé L, Baron L, Chany AC, Tresse C, Saint-Auret S, Jönsson F, Le Chevalier F, Bruhns P, Bismuth G, Hidalgo-Lucas S, Bisson JF, Blanchard N, Demangel C. Shaping mycolactone for therapeutic use against inflammatory disorders. Sci Transl Med 2016; 7:289ra85. [PMID: 26019221 DOI: 10.1126/scitranslmed.aab0458] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Inflammation adversely affects the health of millions of people worldwide, and there is an unmet medical need for better anti-inflammatory drugs. We evaluated the therapeutic interest of mycolactone, a polyketide-derived macrolide produced by Mycobacterium ulcerans. Bacterial production of mycolactone in human skin causes a combination of ulcerative, analgesic, and anti-inflammatory effects. Whereas ulcer formation is mediated by the proapoptotic activity of mycolactone on skin cells via hyperactivation of Wiskott-Aldrich syndrome proteins, analgesia results from neuronal hyperpolarization via signaling through angiotensin II type 2 receptors. Mycolactone also blunts the capacity of immune cells to produce inflammatory mediators by an independent mechanism of protein synthesis blockade. In an attempt to isolate the structural determinants of mycolactone's immunosuppressive activity, we screened a library of synthetic subunits of mycolactone for inhibition of cytokine production by activated T cells. The minimal structure retaining immunosuppressive activity was a truncated version of mycolactone, missing one of the two core-branched polyketide chains. This compound inhibited the inflammatory cytokine responses of human primary cells at noncytotoxic doses and bound to angiotensin II type 2 receptors comparably to mycolactone in vitro. Notably, it was considerably less toxic than mycolactone in human primary dermal fibroblasts modeling ulcerative activity. In mouse models of human diseases, it conferred systemic protection against chronic skin inflammation and inflammatory pain, with no apparent side effects. In addition to establishing the anti-inflammatory potency of mycolactone in vivo, our study therefore highlights the translational potential of mycolactone core-derived structures as prospective immunosuppressants.
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Affiliation(s)
- Laure Guenin-Macé
- Institut Pasteur, Unité d'Immunobiologie de l'Infection, Paris 75015, France. CNRS URA 1961, Paris 75015, France
| | - Ludivine Baron
- Institut Pasteur, Unité d'Immunobiologie de l'Infection, Paris 75015, France. CNRS URA 1961, Paris 75015, France
| | - Anne-Caroline Chany
- Université de Strasbourg, Laboratoire de Chimie Moléculaire, ECPM-CNRS UMR 7509, Strasbourg 67087, France
| | - Cédric Tresse
- Université de Strasbourg, Laboratoire de Chimie Moléculaire, ECPM-CNRS UMR 7509, Strasbourg 67087, France
| | - Sarah Saint-Auret
- Université de Strasbourg, Laboratoire de Chimie Moléculaire, ECPM-CNRS UMR 7509, Strasbourg 67087, France
| | - Friederike Jönsson
- Institut Pasteur, Unité Anticorps en Thérapie et Pathologie, Paris 75015, France. INSERM U760, Paris 75015, France
| | - Fabien Le Chevalier
- Institut Pasteur, Unité d'Immunobiologie de l'Infection, Paris 75015, France
| | - Pierre Bruhns
- Institut Pasteur, Unité Anticorps en Thérapie et Pathologie, Paris 75015, France. INSERM U760, Paris 75015, France
| | - Georges Bismuth
- INSERM U1016, Institut Cochin, Paris 75014, France. Université Paris Descartes, Paris 75014, France. CNRS UMR 8104, Paris 75014, France
| | - Sophie Hidalgo-Lucas
- ETAP, Inflammation, Dermatologie et Toxicologie, Vandœuvre-lès-Nancy 54500, France
| | - Jean-François Bisson
- ETAP, Inflammation, Dermatologie et Toxicologie, Vandœuvre-lès-Nancy 54500, France
| | - Nicolas Blanchard
- Université de Strasbourg, Laboratoire de Chimie Moléculaire, ECPM-CNRS UMR 7509, Strasbourg 67087, France
| | - Caroline Demangel
- Institut Pasteur, Unité d'Immunobiologie de l'Infection, Paris 75015, France. CNRS URA 1961, Paris 75015, France.
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90
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McKenna M, Simmonds RE, High S. Mechanistic insights into the inhibition of Sec61-dependent co- and post-translational translocation by mycolactone. J Cell Sci 2016; 129:1404-15. [PMID: 26869228 PMCID: PMC4852723 DOI: 10.1242/jcs.182352] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/03/2016] [Indexed: 12/17/2022] Open
Abstract
The virulence factor mycolactone is responsible for the immunosuppression and tissue necrosis that characterise Buruli ulcer, a disease caused by infection with Mycobacterium ulcerans In this study, we confirm that Sec61, the protein-conducting channel that coordinates entry of secretory proteins into the endoplasmic reticulum, is a primary target of mycolactone, and characterise the nature of its inhibitory effect. We conclude that mycolactone constrains the ribosome-nascent-chain-Sec61 complex, consistent with its broad-ranging perturbation of the co-translational translocation of classical secretory proteins. In contrast, the effect of mycolactone on the post-translational ribosome-independent translocation of short secretory proteins through the Sec61 complex is dependent on both signal sequence hydrophobicity and the translocation competence of the mature domain. Changes to protease sensitivity strongly suggest that mycolactone acts by inducing a conformational change in the pore-forming Sec61α subunit. These findings establish that mycolactone inhibits Sec61-mediated protein translocation and highlight differences between the co- and post-translational routes that the Sec61 complex mediates. We propose that mycolactone also provides a useful tool for further delineating the molecular mechanisms of Sec61-dependent protein translocation.
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Affiliation(s)
- Michael McKenna
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
| | - Rachel E Simmonds
- Department of Microbial Sciences, School of Bioscience and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Stephen High
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
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91
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do Vale A, Cabanes D, Sousa S. Bacterial Toxins as Pathogen Weapons Against Phagocytes. Front Microbiol 2016; 7:42. [PMID: 26870008 PMCID: PMC4734073 DOI: 10.3389/fmicb.2016.00042] [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: 10/16/2015] [Accepted: 01/11/2016] [Indexed: 12/31/2022] Open
Abstract
Bacterial toxins are virulence factors that manipulate host cell functions and take over the control of vital processes of living organisms to favor microbial infection. Some toxins directly target innate immune cells, thereby annihilating a major branch of the host immune response. In this review we will focus on bacterial toxins that act from the extracellular milieu and hinder the function of macrophages and neutrophils. In particular, we will concentrate on toxins from Gram-positive and Gram-negative bacteria that manipulate cell signaling or induce cell death by either imposing direct damage to the host cells cytoplasmic membrane or enzymatically modifying key eukaryotic targets. Outcomes regarding pathogen dissemination, host damage and disease progression will be discussed.
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Affiliation(s)
- Ana do Vale
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Fish Immunology and Vaccinology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
| | - Didier Cabanes
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
| | - Sandra Sousa
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
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92
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Adusumilli S, Haydel SE. In vitro antibacterial activity and in vivo efficacy of hydrated clays on Mycobacterium ulcerans growth. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 16:40. [PMID: 26833071 PMCID: PMC4734862 DOI: 10.1186/s12906-016-1020-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Accepted: 01/27/2016] [Indexed: 12/26/2022]
Abstract
Background Buruli ulcer, caused by Mycobacterium ulcerans, is a localized skin lesion that can progress to extensive ulceration and necrosis if left untreated. Unpublished studies of hydrated clays for therapeutic, topical treatment of Buruli ulcer suggest that specific clay mineral products may have beneficial effects on wound healing. In this study, we evaluated the in vitro antibacterial activity of a panel of clay mixtures and their derivative leachates against M. ulcerans and assessed the in vivo efficacy of topically-applied, hydrated clays on Buruli ulcer progression in mice infected with M. ulcerans. Methods M. ulcerans 1615 was incubated with 10 % suspensions of CB07, CB08, CB09, CB10, and BY07 clay mixtures, and survival was determined over 28 days. For animal experiments, we examined the effect of topical hydrated clay therapy on Buruli ulcer progression in vivo in mouse tails subcutaneously infected with M. ulcerans 1615. Results The CB07, CB08, and CB09 clays exhibited bactericidal activity against M. ulcerans after 7, 14, 21, and 28 days of incubation. In contrast, clay leachates exhibited inhibitory, bacteriostatic effects on M. ulcerans growth in vitro. After establishing an ulcerative M. ulcerans infection for three months, ulcerated regions of the tails were treated once daily (five consecutive days per week) for 22 days with hydrated CB09 clay poultices. Mice in the clay treatment group exhibited healing as assessed by gross morphological changes and a reduction in M. ulcerans present in the wounds. Conclusions These data reveal that specific clays exhibit in vitro bactericidal activity against M. ulcerans and that hydrated clay poultices may offer a complementary and integrative strategy for topically treating Buruli ulcer disease.
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93
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Niang F, Sarfo FS, Frimpong M, Guenin-Macé L, Wansbrough-Jones M, Stinear T, Phillips RO, Demangel C. Metabolomic profiles delineate mycolactone signature in Buruli ulcer disease. Sci Rep 2015; 5:17693. [PMID: 26634444 PMCID: PMC4669498 DOI: 10.1038/srep17693] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 11/02/2015] [Indexed: 11/09/2022] Open
Abstract
Infection of human skin with Mycobacterium ulcerans, the causative agent of Buruli ulcer, is associated with the systemic diffusion of a bacterial macrolide named mycolactone. Patients with progressive disease show alterations in their serum proteome, likely reflecting the inhibition of secreted protein production by mycolactone at the cellular level. Here, we used semi-quantitative metabolomics to characterize metabolic perturbations in serum samples of infected individuals, and human cells exposed to mycolactone. Among the 430 metabolites profiled across 20 patients and 20 healthy endemic controls, there were significant differences in the serum levels of hexoses, steroid hormones, acylcarnitines, purine, heme, bile acids, riboflavin and lysolipids. In parallel, analysis of 292 metabolites in human T cells treated or not with mycolactone showed alterations in hexoses, lysolipids and purine catabolites. Together, these data demonstrate that M. ulcerans infection causes systemic perturbations in the serum metabolome that can be ascribed to mycolactone. Of particular importance to Buruli ulcer pathogenesis is that changes in blood sugar homeostasis in infected patients are mirrored by alterations in hexose metabolism in mycolactone-exposed cells.
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Affiliation(s)
- Fatoumata Niang
- Institut Pasteur, Unité d'Immunobiologie de l'Infection, Paris, France.,CNRS URA 1961, Paris, France
| | | | | | - Laure Guenin-Macé
- Institut Pasteur, Unité d'Immunobiologie de l'Infection, Paris, France.,CNRS URA 1961, Paris, France
| | | | - Timothy Stinear
- University of Melbourne, Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Richard O Phillips
- Komfo Anokye Teaching Hospital, Kumasi, Ghana.,Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Caroline Demangel
- Institut Pasteur, Unité d'Immunobiologie de l'Infection, Paris, France.,CNRS URA 1961, Paris, France
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94
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Shah JA, Berrington WR, Vary JC, Wells RD, Peterson GJ, Kunwar CB, Khadge S, Hagge DA, Hawn TR. Genetic Variation in Toll-Interacting Protein Is Associated With Leprosy Susceptibility and Cutaneous Expression of Interleukin 1 Receptor Antagonist. J Infect Dis 2015; 213:1189-97. [PMID: 26610735 DOI: 10.1093/infdis/jiv570] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 11/19/2015] [Indexed: 01/03/2023] Open
Abstract
Leprosy is a chronic disease characterized by skin and peripheral nerve pathology and immune responses that fail to control Mycobacterium leprae. Toll-interacting protein (TOLLIP) regulates Toll-like receptor (TLR) and interleukin 1 receptor (IL-1R) signaling against mycobacteria. We analyzed messenger RNA (mRNA) expression of candidate immune genes in skin biopsy specimens from 85 individuals with leprosy. TOLLIP mRNA was highly and specifically correlated with IL-1R antagonist (IL-1Ra). In a case-control gene-association study with 477 cases and 1021 controls in Nepal, TOLLIP single-nucleotide polymorphism rs3793964 TT genotype was associated with increased susceptibility to leprosy (recessive, P = 1.4 × 10(-3)) and with increased skin expression of TOLLIP and IL-1Ra. Stimulation of TOLLIP-deficient monocytes with M. leprae produced significantly less IL-1Ra (P < .001), compared with control. These data suggest that M. leprae upregulates IL-1Ra by a TOLLIP-dependent mechanism. Inhibition of TOLLIP may decrease an individual's susceptibility to leprosy and offer a novel therapeutic target for IL-1-dependent diseases.
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Affiliation(s)
- Javeed A Shah
- University of Washington School of Medicine, Seattle, Washington
| | | | - James C Vary
- University of Washington School of Medicine, Seattle, Washington Puget Sound VA Health Care System, Seattle, Washington
| | - Richard D Wells
- University of Washington School of Medicine, Seattle, Washington
| | | | - Chhatra B Kunwar
- Mycobacterial Research Laboratories, Anandaban Hospital, Kathmandu, Nepal
| | - Saraswoti Khadge
- Mycobacterial Research Laboratories, Anandaban Hospital, Kathmandu, Nepal
| | - Deanna A Hagge
- Mycobacterial Research Laboratories, Anandaban Hospital, Kathmandu, Nepal
| | - Thomas R Hawn
- University of Washington School of Medicine, Seattle, Washington
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95
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Lepra und Buruli-Ulkus. Monatsschr Kinderheilkd 2015. [DOI: 10.1007/s00112-015-3378-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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96
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Brown CA, Aggarwal VK. Short Convergent Synthesis of the Mycolactone Core Through Lithiation-Borylation Homologations. Chemistry 2015; 21:13900-3. [PMID: 26332797 PMCID: PMC6519258 DOI: 10.1002/chem.201503122] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Indexed: 12/17/2022]
Abstract
Using iterative lithiation-borylation homologations, the mycolactone toxin core has been synthesized in 13 steps and 17% overall yield. The rapid build-up of molecular complexity, high convergence and high stereoselectivity are noteworthy features of this synthesis.
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Affiliation(s)
- Christopher A Brown
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS (UK)
| | - Varinder K Aggarwal
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS (UK).
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97
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Kalies KU, Römisch K. Inhibitors of Protein Translocation Across the ER Membrane. Traffic 2015; 16:1027-38. [PMID: 26122014 DOI: 10.1111/tra.12308] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/18/2015] [Accepted: 06/22/2015] [Indexed: 12/21/2022]
Abstract
Protein translocation into the endoplasmic reticulum (ER) constitutes the first step of protein secretion. ER protein import is essential in all eukaryotic cells and is particularly critical in fast-growing tumour cells. Thus, the process can serve as target both for potential cancer drugs and for bacterial virulence factors. Inhibitors of protein transport across the ER membrane range from broad-spectrum to highly substrate-specific and can interfere with virtually any stage of this multistep process, and even with transport of endocytosed antigens into the cytosol for cross-presentation.
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Affiliation(s)
- Kai-Uwe Kalies
- Institute of Biology, CSCM, University of Lübeck, Lübeck, Germany
| | - Karin Römisch
- Department of Microbiology, Faculty of Natural Sciences and Technology VIII, Saarland University, 66123, Saarbrücken, Germany
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98
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Ogbechi J, Ruf MT, Hall BS, Bodman-Smith K, Vogel M, Wu HL, Stainer A, Esmon CT, Ahnström J, Pluschke G, Simmonds RE. Mycolactone-Dependent Depletion of Endothelial Cell Thrombomodulin Is Strongly Associated with Fibrin Deposition in Buruli Ulcer Lesions. PLoS Pathog 2015; 11:e1005011. [PMID: 26181660 PMCID: PMC4504485 DOI: 10.1371/journal.ppat.1005011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/07/2015] [Indexed: 01/21/2023] Open
Abstract
A well-known histopathological feature of diseased skin in Buruli ulcer (BU) is coagulative necrosis caused by the Mycobacterium ulcerans macrolide exotoxin mycolactone. Since the underlying mechanism is not known, we have investigated the effect of mycolactone on endothelial cells, focussing on the expression of surface anticoagulant molecules involved in the protein C anticoagulant pathway. Congenital deficiencies in this natural anticoagulant pathway are known to induce thrombotic complications such as purpura fulimans and spontaneous necrosis. Mycolactone profoundly decreased thrombomodulin (TM) expression on the surface of human dermal microvascular endothelial cells (HDMVEC) at doses as low as 2ng/ml and as early as 8hrs after exposure. TM activates protein C by altering thrombin’s substrate specificity, and exposure of HDMVEC to mycolactone for 24 hours resulted in an almost complete loss of the cells’ ability to produce activated protein C. Loss of TM was shown to be due to a previously described mechanism involving mycolactone-dependent blockade of Sec61 translocation that results in proteasome-dependent degradation of newly synthesised ER-transiting proteins. Indeed, depletion from cells determined by live-cell imaging of cells stably expressing a recombinant TM-GFP fusion protein occurred at the known turnover rate. In order to determine the relevance of these findings to BU disease, immunohistochemistry of punch biopsies from 40 BU lesions (31 ulcers, nine plaques) was performed. TM abundance was profoundly reduced in the subcutis of 78% of biopsies. Furthermore, it was confirmed that fibrin deposition is a common feature of BU lesions, particularly in the necrotic areas. These findings indicate that there is decreased ability to control thrombin generation in BU skin. Mycolactone’s effects on normal endothelial cell function, including its ability to activate the protein C anticoagulant pathway are strongly associated with this. Fibrin-driven tissue ischemia could contribute to the development of the tissue necrosis seen in BU lesions. Buruli ulcer (BU) is a neglected tropical disease that is most common in West Africa and parts of Australia, but has been reported from over 30 countries worldwide. The symptoms are painless ulcers of the skin caused by a bacterial infection. The bacteria, Mycobacterium ulcerans, produce a macrolide toxin called mycolactone. In this manuscript, we have studied the effects of mycolactone on endothelial cells, specialised cells that line blood vessels and form capillaries. One of the most important functions of these cells is to prevent blood from clotting inside the vessels. We show that mycolactone reduces the ability of cultured endothelial cells to anticoagulate blood, by blocking the expression of a protein called thrombomodulin. We went on to examine samples of BU patient skin and found that thrombomodulin is also reduced here, and that in contrast to normal skin large amounts of fibrin (one of the main constituents of blood clots) were present. This means that it may be useful to consider whether anticoagulants might improve the response to antibiotics and thereby improve treatment outcomes for BU patients.
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Affiliation(s)
- Joy Ogbechi
- Department of Microbial and Cellular Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Marie-Thérèse Ruf
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Belinda S. Hall
- Department of Microbial and Cellular Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Katherine Bodman-Smith
- Department of Microbial and Cellular Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Moritz Vogel
- Section Clinical Tropical Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Hua-Lin Wu
- Department of Biochemistry and Molecular Biology, National Cheng Kung University, Tainan, Taiwan
| | - Alexander Stainer
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Charles T. Esmon
- Coagulation Biology Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Josefin Ahnström
- Centre for Haematology, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Gerd Pluschke
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Rachel E. Simmonds
- Department of Microbial and Cellular Sciences, School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
- * E-mail:
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99
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Li X, Babu VS, Kishi Y. Stereoselective total synthesis and stereochemistry confirmation of photo-mycolactones. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2014.12.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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100
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Rahman MA, Sobia P, Dwivedi VP, Bhawsar A, Singh DK, Sharma P, Moodley P, Van Kaer L, Bishai WR, Das G. Mycobacterium tuberculosis TlyA Protein Negatively Regulates T Helper (Th) 1 and Th17 Differentiation and Promotes Tuberculosis Pathogenesis. J Biol Chem 2015; 290:14407-17. [PMID: 25847237 PMCID: PMC4505508 DOI: 10.1074/jbc.m115.653600] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Indexed: 12/30/2022] Open
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis, is an ancient pathogen and a major cause of death worldwide. Although various virulence factors of M. tuberculosis have been identified, its pathogenesis remains incompletely understood. TlyA is a virulence factor in several bacterial infections and is evolutionarily conserved in many Gram-positive bacteria, but its function in M. tuberculosis pathogenesis has not been elucidated. Here, we report that TlyA significantly contributes to the pathogenesis of M. tuberculosis. We show that a TlyA mutant M. tuberculosis strain induces increased IL-12 and reduced IL-1β and IL-10 cytokine responses, which sharply contrasts with the immune responses induced by wild type M. tuberculosis. Furthermore, compared with wild type M. tuberculosis, TlyA-deficient M. tuberculosis bacteria are more susceptible to autophagy in macrophages. Consequently, animals infected with the TlyA mutant M. tuberculosis organisms exhibited increased host-protective immune responses, reduced bacillary load, and increased survival compared with animals infected with wild type M. tuberculosis. Thus, M. tuberculosis employs TlyA as a host evasion factor, thereby contributing to its virulence.
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Affiliation(s)
- Md Aejazur Rahman
- From the School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, 4001 South Africa
| | - Parveen Sobia
- From the School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, 4001 South Africa
| | - Ved Prakash Dwivedi
- From the School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, 4001 South Africa
| | - Aakansha Bhawsar
- the Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
| | - Dhiraj Kumar Singh
- the Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
| | - Pawan Sharma
- the North Eastern Region Biotechnology Programme Management Cell, Defense Colony, New Delhi, India
| | - Prashini Moodley
- From the School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, 4001 South Africa
| | - Luc Van Kaer
- the Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - William R Bishai
- the Center for Tuberculosis Research, Department of Medicine, Division of Infectious Diseases, Johns Hopkins School of Medicine, Baltimore, Maryland 21231-1001, and
| | - Gobardhan Das
- From the School of Laboratory Medicine and Medical Science, University of KwaZulu-Natal, Durban, 4001 South Africa, the Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
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