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Fabris F, Megighian A, Rossetto O, Simonato M, Schiavo G, Pirazzini M, Montecucco C. Local Tetanus Begins with a Neuromuscular Junction Paralysis around the Site of Tetanus Neurotoxin Release due to Cleavage of the Vesicle-Associated Membrane Protein. THE AMERICAN JOURNAL OF PATHOLOGY 2024; 194:1752-1763. [PMID: 38885925 DOI: 10.1016/j.ajpath.2024.05.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 05/14/2024] [Accepted: 05/23/2024] [Indexed: 06/20/2024]
Abstract
Local tetanus develops when limited amounts of tetanus neurotoxin (TeNT) are released by Clostridium tetani generated from spores inside a necrotic wound. Within days, a spastic paralysis restricted to the muscles of the affected anatomical area develops. This paralysis follows the retrograde transport of TeNT inside the axons of motoneurons and its uptake by inhibitory interneurons with cleavage of a vesicle-associated membrane protein required for neurotransmitter release. Consequently, incontrollable excitation of motoneurons causes contractures of innervated muscles and leads to local spastic paralysis. Here, the initial events occurring close to the site of TeNT release were investigated in a mouse model of local tetanus. A peripheral flaccid paralysis was found to occur, before or concurrent to the spastic paralysis. At variance from the confined TeNT proteolytic activity taking place within motor neuron terminals, central protein cleavage was detected within inhibitory interneurons controlling motor neuron efferents innervating muscle groups distant from the site of TeNT release. These results indicate peripheral activity of TeNT in tetanus and explains why the spastic paralysis observed in local tetanus, although confined to single limbs, generally affects multiple muscles. The initial TeNT neuroparalytic activity can be detected by measuring the compound muscle action potential, providing a very early diagnosis and therapy, thus preventing the ensuing life-threatening generalized tetanus.
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Affiliation(s)
- Federico Fabris
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Aram Megighian
- Department of Biomedical Sciences, University of Padua, Padua, Italy; Padua Neuroscience Center, University of Padua, Padua, Italy
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padua, Padua, Italy; Center of Myology CIR-Myo, University of Padua, Padua, Italy; Institute of Neuroscience, National Research Council, Padua, Italy
| | - Morena Simonato
- Institute of Neuroscience, National Research Council, Padua, Italy
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases and UCL Queen Square Motor Neuron Disease Centre, UCL Queen Square Institute of Neurology, London, United Kingdom; UK Dementia Research Institute, University College London, London, United Kingdom
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padua, Padua, Italy; Center of Myology CIR-Myo, University of Padua, Padua, Italy.
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padua, Padua, Italy; Institute of Neuroscience, National Research Council, Padua, Italy.
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2
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Yeo JC, Tay FP, Bennion R, Loss O, Maignel J, Pons L, Foster K, Beard M, Bard F. Botulinum toxin intoxication requires retrograde transport and membrane translocation at the ER in RenVM neurons. eLife 2024; 12:RP92806. [PMID: 39196607 DOI: 10.7554/elife.92806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/29/2024] Open
Abstract
Botulinum neurotoxin A (BoNT/A) is a highly potent proteolytic toxin specific for neurons with numerous clinical and cosmetic uses. After uptake at the synapse, the protein is proposed to translocate from synaptic vesicles to the cytosol through a self-formed channel. Surprisingly, we found that after intoxication proteolysis of a fluorescent reporter occurs in the neuron soma first and then centrifugally in neurites. To investigate the molecular mechanisms at play, we use a genome-wide siRNA screen in genetically engineered neurons and identify over three hundred genes. An organelle-specific split-mNG complementation indicates BoNT/A traffic from the synapse to the soma-localized Golgi in a retromer-dependent fashion. The toxin then moves to the ER and appears to require the Sec61 complex for retro-translocation to the cytosol. Our study identifies genes and trafficking processes hijacked by the toxin, revealing a new pathway mediating BoNT/A cellular toxicity.
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Affiliation(s)
- Jeremy C Yeo
- Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Felicia P Tay
- Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Rebecca Bennion
- Centre de Recherche en Cancérologie de Marseille, Aix Marseille Université, Inserm, CNRS, Institut Paoli-Calmettes, Equipe Leader Fondation ARC 2021, Marseille, France
| | - Omar Loss
- Ipsen Bioinnovation, London, United Kingdom
| | | | | | | | | | - Frederic Bard
- Institute of Molecular and Cell Biology, Singapore, Singapore
- Centre de Recherche en Cancérologie de Marseille, Aix Marseille Université, Inserm, CNRS, Institut Paoli-Calmettes, Equipe Leader Fondation ARC 2021, Marseille, France
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3
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Rawson AM, Dempster AW, Humphreys CM, Minton NP. Pathogenicity and virulence of Clostridium botulinum. Virulence 2023; 14:2205251. [PMID: 37157163 PMCID: PMC10171130 DOI: 10.1080/21505594.2023.2205251] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
Clostridium botulinum, a polyphyletic Gram-positive taxon of bacteria, is classified purely by their ability to produce botulinum neurotoxin (BoNT). BoNT is the primary virulence factor and the causative agent of botulism. A potentially fatal disease, botulism is classically characterized by a symmetrical descending flaccid paralysis, which is left untreated can lead to respiratory failure and death. Botulism cases are classified into three main forms dependent on the nature of intoxication; foodborne, wound and infant. The BoNT, regarded as the most potent biological substance known, is a zinc metalloprotease that specifically cleaves SNARE proteins at neuromuscular junctions, preventing exocytosis of neurotransmitters, leading to muscle paralysis. The BoNT is now used to treat numerous medical conditions caused by overactive or spastic muscles and is extensively used in the cosmetic industry due to its high specificity and the exceedingly small doses needed to exert long-lasting pharmacological effects. Additionally, the ability to form endospores is critical to the pathogenicity of the bacteria. Disease transmission is often facilitated via the metabolically dormant spores that are highly resistant to environment stresses, allowing persistence in the environment in unfavourable conditions. Infant and wound botulism infections are initiated upon germination of the spores into neurotoxin producing vegetative cells, whereas foodborne botulism is attributed to ingestion of preformed BoNT. C. botulinum is a saprophytic bacterium, thought to have evolved its potent neurotoxin to establish a source of nutrients by killing its host.
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Affiliation(s)
- Alexander M Rawson
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The Biodiscovery Institute, The University of Nottingham, Nottingham, UK
| | - Andrew W Dempster
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The Biodiscovery Institute, The University of Nottingham, Nottingham, UK
| | - Christopher M Humphreys
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The Biodiscovery Institute, The University of Nottingham, Nottingham, UK
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4
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Ambrin G, Cai S, Singh BR. Critical analysis in the advancement of cell-based assays for botulinum neurotoxin. Crit Rev Microbiol 2023; 49:1-17. [PMID: 35212259 DOI: 10.1080/1040841x.2022.2035315] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The study on botulinum neurotoxins (BoNTs) has rapidly evolved for their structure and functions as opposed to them being poisons or cures. Since their discoveries, the scientific community has come a long way in understanding BoNTs' structure and biological activity. Given its current application as a tool for understanding neurocellular activity and as a drug against over 800 neurological disorders, relevant and sensitive assays have become critical for biochemical, physiological, and pharmacological studies. The natural entry of the toxin being ingestion, it has also become important to examine its mechanism while crossing the epithelial cell barrier. Several techniques and methodologies have been developed, for its entry, pharmacokinetics, and biological activity for identification, and drug efficacy both in vivo and in vitro conditions. However, each of them presents its own challenges. The cell-based assay is a platform that exceeds the sensitivity of mouse bioassay while encompassing all the steps of intoxication including cell binding, transcytosis, endocytosis, translocation and proteolytic activity. In this article we review in detail both the neuronal and nonneuronal based cellular interaction of BoNT involving its transportation, and interaction with the targeted cells, and intracellular activities.
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Affiliation(s)
- Ghuncha Ambrin
- Department of Biomedical Engineering and Biotechnology, University of Massachusetts, Dartmouth, MA, USA.,Department of Chemistry and Biochemistry, University of Massachusetts, Dartmouth, MA, USA
| | - Shuowei Cai
- Department of Chemistry and Biochemistry, University of Massachusetts, Dartmouth, MA, USA
| | - Bal Ram Singh
- Institute of Advanced Sciences, Botulinum Research Center, Dartmouth, MA, USA
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5
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Saricaoglu B, Gültekin Subaşı B, Karbancioglu-Guler F, Lorenzo JM, Capanoglu E. Phenolic compounds as natural microbial toxin detoxifying agents. Toxicon 2023; 222:106989. [PMID: 36509264 DOI: 10.1016/j.toxicon.2022.106989] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022]
Abstract
Despite the abundance of promising studies, developments, and improvements about the elimination of microbial toxins from food matrices, they are still considered as one of the major food safety problems due to the lack of their complete avoidance even today. Every year, many crops and foodstuffs have to be discarded due to unconstrained contamination and/or production of microbial toxins. Furthermore, the difficulty for the detection of toxin presence and determination of its level in foods may lead to acute or chronic health problems in many individuals. On the other hand, phenolic compounds might be considered as microbial toxin detoxification agents because of their inhibition effect on the toxin synthesis of microorganisms or exhibiting protective effects against varying damaging mechanisms caused by toxins. In this study, the effect of phenolic compounds on the synthesis of bacterial toxins and mycotoxins is comprehensively reviewed. The potential curing effect of phenolic compounds against toxin-induced damages has also been discussed. Consequently, phenolic compounds are indicated as promising, and considerable natural preservatives against toxin damages and their detoxification potentials are pronounced.
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Affiliation(s)
- Beyza Saricaoglu
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey
| | - Büşra Gültekin Subaşı
- Hafik Kamer Ornek Vocational School, Sivas Cumhuriyet University, 58140, Sivas, Turkey
| | - Funda Karbancioglu-Guler
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey
| | - Jose Manuel Lorenzo
- Centro Tecnológico de La Carne de Galicia, Parque Tecnológico de Galicia, Avd. Galicia nº 4, San Cibrao das Viñas, 32900 Ourense, Spain; Universidade de Vigo, Área de Tecnoloxía dos Alimentos, Facultade de Ciencias, 32004 Ourense, Spain
| | - Esra Capanoglu
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey.
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6
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Gardner AP, Barbieri JT, Pellett S. How Botulinum Neurotoxin Light Chain A1 Maintains Stable Association with the Intracellular Neuronal Plasma Membrane. Toxins (Basel) 2022; 14:toxins14120814. [PMID: 36548711 PMCID: PMC9783275 DOI: 10.3390/toxins14120814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Botulinum neurotoxin serotype A (BoNT/A) is the most potent protein toxin for humans and is utilized as a therapy for numerous neurologic diseases. BoNT/A comprises a catalytic Light Chain (LC/A) and a Heavy Chain (HC/A) and includes eight subtypes (BoNT/A1-/A8). Previously we showed BoNT/A potency positively correlated with stable localization on the intracellular plasma membrane and identified a low homology domain (amino acids 268-357) responsible for LC/A1 stable co-localization with SNAP-25 on the plasma membrane, while LC/A3 was present in the cytosol of Neuro2A cells. In the present study, steady-state- and live-imaging of a cytosolic LC/A3 derivative (LC/A3V) engineered to contain individual structural elements of the A1 LDH showed that a 59 amino acid region (275-334) termed the MLD was sufficient to direct LC/A3V from the cytosol to the plasma membrane co-localized with SNAP-25. Informatics and experimental validation of the MLD-predicted R1 region (an α-helix, residues 275-300) and R2 region (a loop, α-helix, loop, residues 302-334) both contribute independent steps to the stable co-localization of LC/A1 with SNAP-25 on the plasma membrane of Neuro-2A cells. Understanding how these structural elements contribute to the overall association of LC/A1 on the plasma membrane may identify the molecular basis for the LC contribution of BoNT/A1 to high potency.
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Affiliation(s)
- Alexander P. Gardner
- Microbiology and Immunology, Medical College, Wisconsin 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Joseph T. Barbieri
- Microbiology and Immunology, Medical College, Wisconsin 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Correspondence: (J.T.B.); (S.P.)
| | - Sabine Pellett
- Department of Bacteriology, Microbial Sciences Building, University of Wisconsin-Madison, 1550 Linden Dr., Madison, WI 53706, USA
- Correspondence: (J.T.B.); (S.P.)
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7
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Auranofin and Baicalin Inhibit Clostridioides difficile Growth and Sporulation: An In vitro Study. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2022. [DOI: 10.22207/jpam.16.3.01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridioides difficile is a principal cause of hospital-acquired gastrointestinal infections, with sporulation and toxin production being key determinants in the disease pathogenesis. Although infections have been escalating and the complications can be life-threatening, the narrow pipeline of approved therapeutics has not witnessed an equivalent surge. With the unfolding of worrisome mutations and antimicrobial resistance, attention has been drawn to either discovering new therapeutics, or even better, repurposing already available ones. Consequently, this study was undertaken to assess the anti-clostridial activity of auranofin, an anti-rheumatic FDA-approved therapeutic; and baicalin, a natural flavone glycoside with reported anti-microbial potential. In comparison with vancomycin, the in vitro efficacy of auranofin and baicalin was tested against hypervirulent C. difficile (BAA-1870TM). Broth suspensions were prepared with and without the three agents and anaerobically incubated. At 24- and 48-hours post-incubation, serial dilutions were prepared and inoculated onto agar plates. Viable cell counts and viable spore counts were then quantified. Meanwhile, toxin production was assessed via ELISA. At a concentration as low as 3 μg/mL, auranofin demonstrated a potent anti-clostridial activity. Both auranofin and baicalin exhibited a remarkable reduction in C. difficile viable cell counts (P-value 0.03 for each) and spore counts (P-values 0.023 and 0.045 respectively). While auranofin and baicalin proved to be non-inferior to vancomycin as inhibitors of C. difficile growth, both drugs proved to be superior to vancomycin in decreasing the spore counts 48-hours post inoculation. Additionally, auranofin markedly reduced C. difficile toxin production (P-value 0.021); a feature that was deficient in both baicalin and vancomycin. To enrich the currently limited repertoire of anti-clostridial drugs, further research is encouraging to compare between the in vivo efficacy of auranofin and that of baicalin. Both agents represent promising approaches that could address the unfulfilled needs in controlling C. difficile infection.
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8
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Hefter H, Samadzadeh S. The Necessity of a Locally Active Antidote in the Clinical Practice of Botulinum Neurotoxin Therapy: Short Communication. Medicina (B Aires) 2022; 58:medicina58070935. [PMID: 35888654 PMCID: PMC9324518 DOI: 10.3390/medicina58070935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/07/2022] [Accepted: 07/13/2022] [Indexed: 11/30/2022] Open
Abstract
Recently, it was demonstrated that copper complexes and 3,4-diaminopyridine can effectively reduce the activity of the botulinum neurotoxin light chain. The aim of the present study was to indicate that treatment with an antidote may have a major influence, not only on the extremely rare disease of botulism, but also on the much more frequently occurring side effects experienced during BoNT therapy. This was a retrospective chart review of patients who were regularly treated with BoNT for various indications. The percentage of patients with clinical signs of overdosing was determined. In patients with facial dystonia, double vision and ptosis occurred as side effects. In patients with cervical dystonia, neck weakness and dysphagia were observed as the most frequent side effects. In oromandibular and oropharyngeal dystonia, abnormal tongue movements and dysphagia occurred frequently. In writer’s cramp and mild post-stroke hand spasticity, severe paresis of the injected and non-injected finger muscles was observed. Additionally, in the BoNT treatment of pain syndromes (such as tension headaches or migraines), neck weakness may occur. Across all indications for clinical BoNT applications, clinical signs of BoNT overdosing may occur in up to 5% of the BoNT-treated patients. Therefore, the development of an antidote for BoNT overdoses would be very much appreciated and would have a major influence on the management of BoNT therapy.
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Affiliation(s)
- Harald Hefter
- Correspondence: ; Tel.: +49-211-811-7025; Fax: +49-211-810-4903
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9
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Pirazzini M, Montecucco C, Rossetto O. Toxicology and pharmacology of botulinum and tetanus neurotoxins: an update. Arch Toxicol 2022; 96:1521-1539. [PMID: 35333944 PMCID: PMC9095541 DOI: 10.1007/s00204-022-03271-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 02/28/2022] [Indexed: 12/27/2022]
Abstract
Tetanus and botulinum neurotoxins cause the neuroparalytic syndromes of tetanus and botulism, respectively, by delivering inside different types of neurons, metalloproteases specifically cleaving the SNARE proteins that are essential for the release of neurotransmitters. Research on their mechanism of action is intensively carried out in order to devise improved therapies based on antibodies and chemical drugs. Recently, major results have been obtained with human monoclonal antibodies and with single chain antibodies that have allowed one to neutralize the metalloprotease activity of botulinum neurotoxin type A1 inside neurons. In addition, a method has been devised to induce a rapid molecular evolution of the metalloprotease domain of botulinum neurotoxin followed by selection driven to re-target the metalloprotease activity versus novel targets with respect to the SNARE proteins. At the same time, an intense and wide spectrum clinical research on novel therapeutics based on botulinum neurotoxins is carried out, which are also reviewed here.
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Affiliation(s)
- Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy.,Centro Interdipartimentale di Ricerca di Miologia, CIR-Myo, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy. .,Institute of Neuroscience, National Research Council, Via Ugo Bassi 58/B, 35131, Padova, Italy.
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy.,Centro Interdipartimentale di Ricerca di Miologia, CIR-Myo, University of Padova, Via U. Bassi 58/B, 35131, Padova, Italy.,Institute of Neuroscience, National Research Council, Via Ugo Bassi 58/B, 35131, Padova, Italy
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10
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Pirazzini M, Grinzato A, Corti D, Barbieri S, Leka O, Vallese F, Tonellato M, Silacci-Fregni C, Piccoli L, Kandiah E, Schiavo G, Zanotti G, Lanzavecchia A, Montecucco C. Exceptionally potent human monoclonal antibodies are effective for prophylaxis and treatment of tetanus in mice. J Clin Invest 2021; 131:151676. [PMID: 34618682 DOI: 10.1172/jci151676] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 09/28/2021] [Indexed: 01/15/2023] Open
Abstract
We used human monoclonal antibodies (humAbs) to study the mechanism of neuron intoxication by tetanus neurotoxin and to evaluate these antibodies as a safe preventive and therapeutic substitute for hyperimmune sera to treat tetanus in mice. By screening memory B cells from immune donors, we selected 2 tetanus neurotoxin-specific mAbs with exceptionally high neutralizing activities and extensively characterized them both structurally and functionally. We found that these antibodies interfered with the binding and translocation of the neurotoxin into neurons by interacting with 2 epitopes, whose identification pinpoints crucial events in the cellular pathogenesis of tetanus. Our observations explain the neutralization ability of these antibodies, which we found to be exceptionally potent in preventing experimental tetanus when injected into mice long before the toxin. Moreover, their Fab derivatives neutralized tetanus neurotoxin in post-exposure experiments, suggesting their potential for therapeutic use via intrathecal injection. As such, we believe these humAbs, as well as their Fab derivatives, meet the requirements to be considered for prophylactic and therapeutic use in human tetanus and are ready for clinical trials.
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Affiliation(s)
- Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | | | | | | | - Oneda Leka
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Francesca Vallese
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Marika Tonellato
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Chiara Silacci-Fregni
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Bellinzona, Switzerland
| | - Luca Piccoli
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Bellinzona, Switzerland
| | | | - Giampietro Schiavo
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology and.,UK Dementia Research Institute, University College London, London, United Kingdom
| | - Giuseppe Zanotti
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Antonio Lanzavecchia
- Institute for Research in Biomedicine, Università della Svizzera Italiana, Bellinzona, Switzerland.,Fondazione Istituto Nazionale Genetica Molecolare, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico di Milano, Milano, Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Institute of Neuroscience, National Research Council, Padova, Italy
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11
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Zanetti G, Mattarei A, Lista F, Rossetto O, Montecucco C, Pirazzini M. Novel Small Molecule Inhibitors That Prevent the Neuroparalysis of Tetanus Neurotoxin. Pharmaceuticals (Basel) 2021; 14:ph14111134. [PMID: 34832916 PMCID: PMC8618345 DOI: 10.3390/ph14111134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/25/2021] [Accepted: 11/04/2021] [Indexed: 01/22/2023] Open
Abstract
Tetanus neurotoxin (TeNT) is a protein exotoxin produced by Clostridium tetani that causes the deadly spastic neuroparalysis of tetanus. It consists of a metalloprotease light chain and of a heavy chain linked via a disulphide bond. TeNT binds to the neuromuscular junction (NMJ) and it is retro-axonally transported into vesicular compartments to the spinal cord, where it is released and taken up by inhibitory interneuron. Therein, the catalytic subunit is translocated into the cytoplasm where it cleaves its target protein VAMP-1/2 with consequent blockage of the release of inhibitory neurotransmitters. Vaccination with formaldehyde inactivated TeNT prevents the disease, but tetanus is still present in countries where vaccination coverage is partial. Here, we show that small molecule inhibitors interfering with TeNT trafficking or with the reduction of the interchain disulphide bond block the activity of the toxin in neuronal cultures and attenuate tetanus symptoms in vivo. These findings are relevant for the development of therapeutics against tetanus based on the inhibition of toxin molecules that are being retro-transported to or are already within the spinal cord and are, thus, not accessible to anti-TeNT immunoglobulins.
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Affiliation(s)
- Giulia Zanetti
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy; (G.Z.); (O.R.)
| | - Andrea Mattarei
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Via F. Marzolo 5, 35131 Padova, Italy;
| | - Florigio Lista
- Scientific Department, Army Medical Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy;
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy; (G.Z.); (O.R.)
- Italian Research Council, Institute of Neuroscience, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy
- CIR-Myo, Centro Interdipartimentale di Ricerca di Miologia, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy; (G.Z.); (O.R.)
- Italian Research Council, Institute of Neuroscience, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy
- Correspondence: (C.M.); (M.P.)
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35121 Padova, Italy; (G.Z.); (O.R.)
- CIR-Myo, Centro Interdipartimentale di Ricerca di Miologia, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy
- Correspondence: (C.M.); (M.P.)
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12
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O'Neil PT, Vasquez-Montes V, Swint-Kruse L, Baldwin MR, Ladokhin AS. Spectroscopic evidence of tetanus toxin translocation domain bilayer-induced refolding and insertion. Biophys J 2021; 120:4763-4776. [PMID: 34555358 PMCID: PMC8595737 DOI: 10.1016/j.bpj.2021.09.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/03/2021] [Accepted: 09/16/2021] [Indexed: 12/21/2022] Open
Abstract
Tetanus neurotoxin (TeNT) is an A-B toxin with three functional domains: endopeptidase, translocation (HCT), and receptor binding. Endosomal acidification triggers HCT to interact with and insert into the membrane, translocating the endopeptidase across the bilayer. Although the function of HCT is well defined, the mechanism by which it accomplishes this task is unknown. To gain insight into the HCT membrane interaction on both local and global scales, we utilized an isolated, beltless HCT variant (bHCT), which retained the ability to release potassium ions from vesicles. To examine which bHCT residues interact with the membrane, we widely sampled the surface of bHCT using 47 single-cysteine variants labeled with the environmentally sensitive fluorophore NBD. At neutral pH, no interaction was observed for any variant. In contrast, all NBD-labeled positions reported environmental change in the presence of acidic pH and membranes containing anionic lipids. We then examined the conformation of inserted bHCT using circular dichroism and intrinsic fluorescence. Upon entering the membrane, bHCT retained predominantly α-helical secondary structure, whereas the tertiary structure exhibited substantial refolding. The use of lipid-attached quenchers revealed that at least one of the three tryptophan residues penetrated deep into the hydrocarbon core of the membrane, suggesting formation of a bHCT transmembrane conformation. The possible conformational topology was further explored with the hydropathy analysis webtool MPEx, which identified a large, potential α-helical transmembrane region. Altogether, the spectroscopic evidence supports a model in which, upon acidification, the majority of TeNT bHCT entered the membrane with a concurrent change in tertiary structure.
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Affiliation(s)
- Pierce T O'Neil
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Victor Vasquez-Montes
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Liskin Swint-Kruse
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas
| | - Michael R Baldwin
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri
| | - Alexey S Ladokhin
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas.
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13
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Hutton ML, Pehlivanoglu H, Vidor CJ, James ML, Thomson MJ, Lyras D. Repurposing auranofin as a Clostridioides difficile therapeutic. J Antimicrob Chemother 2021; 75:409-417. [PMID: 31642901 DOI: 10.1093/jac/dkz430] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/12/2019] [Accepted: 09/18/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Clostridioides difficile (previously Clostridium difficile) is the leading cause of nosocomial, antibiotic-associated diarrhoea worldwide. Currently, the gold standard of treatment for C. difficile infection (CDI) is vancomycin or metronidazole, although these antibiotics also perturb the protective resident microbiota, often resulting in disease relapse. Thus, an urgent need remains for the development of new treatment strategies. Auranofin is an FDA-approved oral antirheumatic drug that was previously shown to inhibit C. difficile vegetative cell growth, toxin production and spore production in vitro. OBJECTIVES To determine the efficacy of auranofin as a CDI therapeutic by examining the effect of treatment on toxin and spore production in vitro and in vivo, and on disease outcomes in mice. METHODS C. difficile cultures were treated with auranofin and examined for effects on sporulation and toxin production by sporulation assay and ELISA, respectively. Mice were pretreated with auranofin prior to infection with C. difficile and monitored for physiological conditions, survival and gut damage compared with control animals. Faeces from mice were analysed to determine whether auranofin reduces sporulation and toxin production in vivo. RESULTS Auranofin significantly reduces sporulation and toxin production under in vitro conditions and in infected mice in vivo. Mice treated with auranofin lost less weight, displayed a significant increase in survival rates and had significantly less toxin-mediated damage in their colon and caecum compared with control mice. CONCLUSIONS Auranofin shows promise as a prospective therapeutic option for C. difficile infections.
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Affiliation(s)
- Melanie L Hutton
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Havva Pehlivanoglu
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Callum J Vidor
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Meagan L James
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
| | - Melanie J Thomson
- School of Medicine, Deakin University, Pigdons Road, Waurn Ponds, Victoria, 3216, Australia
| | - Dena Lyras
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria, 3800, Australia
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14
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Hefter H, Samadzadeh S. Effective Treatment of Neurological Symptoms with Normal Doses of Botulinum Neurotoxin in Wilson's Disease: Six Cases and Literature Review. Toxins (Basel) 2021; 13:toxins13040241. [PMID: 33805281 PMCID: PMC8065630 DOI: 10.3390/toxins13040241] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 03/16/2021] [Accepted: 03/22/2021] [Indexed: 11/21/2022] Open
Abstract
Recent cell-based and animal experiments have demonstrated an effective reduction in botulinum neurotoxin A (BoNT/A) by copper. Aim: We aimed to analyze whether the successful symptomatic BoNT/A treatment of patients with Wilson’s disease (WD) corresponds with unusually high doses per session. Among the 156 WD patients regularly seen at the outpatient department of the university hospital in Düsseldorf (Germany), only 6 patients had been treated with BoNT/A during the past 5 years. The laboratory findings, indications for BoNT treatment, preparations, and doses per session were extracted retrospectively from the charts. These parameters were compared with those of 13 other patients described in the literature. BoNT/A injection therapy is a rare (<4%) symptomatic treatment in WD, only necessary in exceptional cases, and is often applied only transiently. In those cases for which dose information was available, the dose per session and indication appear to be within usual limits. Despite the evidence that copper can interfere with the botulinum toxin in preclinical models, patients with WD do not require higher doses of the toxin than other patients with dystonia.
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Affiliation(s)
| | - Sara Samadzadeh
- Correspondence: ; Tel.: +49-211-811-7025; Fax: 49-211-810-4903
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15
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Megighian A, Pirazzini M, Fabris F, Rossetto O, Montecucco C. Tetanus and tetanus neurotoxin: From peripheral uptake to central nervous tissue targets. J Neurochem 2021; 158:1244-1253. [PMID: 33629408 DOI: 10.1111/jnc.15330] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/28/2021] [Accepted: 02/15/2021] [Indexed: 12/12/2022]
Abstract
Tetanus is a deadly but preventable disease caused by a protein neurotoxin produced by Clostridium tetani. Spores of C. tetani may contaminate a necrotic wound and germinate into a vegetative bacterium that releases a toxin, termed tetanus neurotoxin (TeNT). TeNT enters the general circulation, binds to peripheral motor neurons and sensory neurons, and is transported retroaxonally to the spinal cord. It then enters inhibitory interneurons and blocks the release of glycine or GABA causing a spastic paralysis. This review attempts to correlate the metalloprotease activity of TeNT and its trafficking and localization into the vertebrate body to the nature and sequence of appearance of the symptoms of tetanus.
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Affiliation(s)
- Aram Megighian
- Dipartimento di scienze Biomediche, Università di Padova, Padova, Italy.,Padova Neuroscience Center, Università di Padova, Padova, Italy
| | - Marco Pirazzini
- Dipartimento di scienze Biomediche, Università di Padova, Padova, Italy
| | - Federico Fabris
- Dipartimento di scienze Biomediche, Università di Padova, Padova, Italy
| | - Ornella Rossetto
- Dipartimento di scienze Biomediche, Università di Padova, Padova, Italy.,Istituto CNR di Neuroscienze, Università di Padova, Padova, Italy
| | - Cesare Montecucco
- Dipartimento di scienze Biomediche, Università di Padova, Padova, Italy.,Istituto CNR di Neuroscienze, Università di Padova, Padova, Italy
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16
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Zuverink M, Barbieri JT. Resolving the Molecular Steps in Clostridial Neurotoxin Light Chain Translocation. JOURNAL OF EXPERIMENTAL NEUROLOGY 2021; 1:123-134. [PMID: 33615314 PMCID: PMC7894615 DOI: 10.33696/neurol.1.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The clostridial neurotoxins (CNTs), botulinum toxin and tetanus toxin, are the most toxic proteins for humans. Neurotoxicity is based upon the specificity of the CNTs for neural host receptors and substrates. CNTs are organized into three domains, a Light Chain (LC) that is a metalloprotease and a Heavy Chain (HC) that has two domains, an N-terminal LC translocation domain (HCN) and a C-terminal receptor binding domain (HCC). While catalysis and receptor binding functions of the CNTs have been developed, our understanding of LC translocation is limited. This is due to the intrinsic complexity of the translocation process and limited tools to assess the step-by-step events in LC translocation. Recently, we developed a novel, cell-based TT-reporter to measure LC translocation as the translocation of a β-lactamase reporter across a vesicle membrane in neurons. Using this approach, we identified a role for a cis-Loop, located within the HCN, in LC translocation. In this commentary, we describe our current understanding of how CNTs mediate LC translocation and place the role of the cis-Loop in the LC translocation process relative to other independent functions that have been implicated in LC translocation. Understanding the basis for LC translocation will enhance the use of CNTs in vaccine development and as human therapies.
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Affiliation(s)
- Madison Zuverink
- Dalhousie University, Department of Biochemistry and Molecular Biology, Halifax, Nova Scotia, Canada
| | - Joseph T Barbieri
- Medical College of Wisconsin, 8701 Watertown Plank Road, BSB2 Rm. 2830, Microbiology and Immunology, Milwaukee, WI 53226, USA
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17
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The 25 kDa H CN Domain of Clostridial Neurotoxins Is Indispensable for Their Neurotoxicity. Toxins (Basel) 2020; 12:toxins12120743. [PMID: 33255952 PMCID: PMC7760224 DOI: 10.3390/toxins12120743] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 11/13/2020] [Accepted: 11/20/2020] [Indexed: 11/17/2022] Open
Abstract
The extraordinarily potent clostridial neurotoxins (CNTs) comprise tetanus neurotoxin (TeNT) and the seven established botulinum neurotoxin serotypes (BoNT/A-G). They are composed of four structurally independent domains: the roles of the catalytically active light chain, the translocation domain HN, and the C-terminal receptor binding domain HCC are largely resolved, but that of the HCN domain sandwiched between HN and HCC has remained unclear. Here, mutants of BoNT/A, BoNT/B, and TeNT were generated by deleting their HCN domains or swapping HCN domains between each other. Both deletion and replacement of TeNT HCN domain by HCNA and HCNB reduced the biological activity similarly, by ~95%, whereas BoNT/A and B deletion mutants displayed >500-fold reduced activity in the mouse phrenic nerve hemidiaphragm assay. Swapping HCN domains between BoNT/A and B hardly impaired their biological activity, but substitution with HCNT did. Binding assays revealed that in the absence of HCN, not all receptor binding sites are equally well accessible. In conclusion, the presence of HCN is vital for CNTs to exert their neurotoxicity. Although structurally similar, the HCN domain of TeNT cannot equally substitute those of BoNT and vice versa, leaving the possibility that HCNT plays a different role in the intoxication mechanism of TeNT.
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18
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Rossetto O, Pirazzini M, Lista F, Montecucco C. The role of the single interchains disulfide bond in tetanus and botulinum neurotoxins and the development of antitetanus and antibotulism drugs. Cell Microbiol 2019; 21:e13037. [PMID: 31050145 PMCID: PMC6899712 DOI: 10.1111/cmi.13037] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/18/2019] [Accepted: 04/30/2019] [Indexed: 01/02/2023]
Abstract
A large number of bacterial toxins consist of active and cell binding protomers linked by an interchain disulfide bridge. The largest family of such disulfide-bridged exotoxins is that of the clostridial neurotoxins that consist of two chains and comprise the tetanus neurotoxins causing tetanus and the botulinum neurotoxins causing botulism. Reduction of the interchain disulfide abolishes toxicity, and we discuss the experiments that revealed the role of this structural element in neuronal intoxication. The redox couple thioredoxin reductase-thioredoxin (TrxR-Trx) was identified as the responsible for reduction of this disulfide occurring on the cytosolic surface of synaptic vesicles. We then discuss the very relevant finding that drugs that inhibit TrxR-Trx also prevent botulism. On this basis, we propose that ebselen and PX-12, two TrxR-Trx specific drugs previously used in clinical trials in humans, satisfy all the requirements for clinical tests aiming at evaluating their capacity to effectively counteract human and animal botulism arising from intestinal toxaemias such as infant botulism.
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Affiliation(s)
- Ornella Rossetto
- Dipartimento di Scienze BiomedicheUniversità di PadovaPaduaItaly
| | - Marco Pirazzini
- Dipartimento di Scienze BiomedicheUniversità di PadovaPaduaItaly
| | - Florigio Lista
- Sezione di Istologia e Biologia MolecolareCentro di ricerca Medica e Veterinaria del Ministero della DifesaRomeItaly
| | - Cesare Montecucco
- Dipartimento di Scienze BiomedicheUniversità di PadovaPaduaItaly
- Istituto Neuroscienze del CNRUniversità di PadovaPaduaItaly
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19
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Pereira C, Rodrigues IS, Pereira LMG, Lisboa J, Pinto RD, Araújo L, Oliveira P, Benz R, Dos Santos NMS, do Vale A. Role of AIP56 disulphide bond and its reduction by cytosolic redox systems for efficient intoxication. Cell Microbiol 2019; 22:e13109. [PMID: 31454143 DOI: 10.1111/cmi.13109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/08/2019] [Accepted: 08/21/2019] [Indexed: 12/14/2022]
Abstract
Apoptosis-inducing protein of 56 kDa (AIP56) is a major virulence factor of Photobacterium damselae subsp. piscicida, a gram-negative pathogen that infects warm water fish species worldwide and causes serious economic losses in aquacultures. AIP56 is a single-chain AB toxin composed by two domains connected by an unstructured linker peptide flanked by two cysteine residues that form a disulphide bond. The A domain comprises a zinc-metalloprotease moiety that cleaves the NF-kB p65, and the B domain is involved in binding and internalisation of the toxin into susceptible cells. Previous experiments suggested that disruption of AIP56 disulphide bond partially compromised toxicity, but conclusive evidences supporting the importance of that bond in intoxication were lacking. Here, we show that although the disulphide bond of AIP56 is dispensable for receptor recognition, endocytosis, and membrane interaction, it needs to be intact for efficient translocation of the toxin into the cytosol. We also show that the host cell thioredoxin reductase-thioredoxin system is involved in AIP56 intoxication by reducing the disulphide bond of the toxin at the cytosol. The present study contributes to a better understanding of the molecular mechanisms operating during AIP56 intoxication and reveals common features shared with other AB toxins.
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Affiliation(s)
- Cassilda Pereira
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Inês S Rodrigues
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Liliana M G Pereira
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Johnny Lisboa
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Rute D Pinto
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Leonor Araújo
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Pedro Oliveira
- EPIUnit, ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany
| | - Nuno M S Dos Santos
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Ana do Vale
- Fish Immunology and Vaccinology Group, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
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20
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Tehran DA, Pirazzini M. Preparation of Cerebellum Granule Neurons from Mouse or Rat Pups and Evaluation of Clostridial Neurotoxin Activity and Their Inhibitors by Western Blot and Immunohistochemistry. Bio Protoc 2018; 8:e2918. [PMID: 34395747 DOI: 10.21769/bioprotoc.2918] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/12/2018] [Accepted: 06/17/2018] [Indexed: 01/29/2023] Open
Abstract
Cerebellar Granule Neurons (CGN) from post-natal rodents have been widely used as a model to study neuronal development, physiology and pathology. CGN cultured in vitro maintain the same features displayed in vivo by mature cerebellar granule cells, including the development of a dense neuritic network, neuronal activity, neurotransmitter release and the expression of neuronal protein markers. Moreover, CGN represent a convenient model for the study of Clostridial Neurotoxins (CNT), most notably known as Tetanus and Botulinum neurotoxins, as they abundantly express both CNT receptors and intraneuronal substrates, i.e., Soluble N-ethylmaleimide-sensitive factor activating protein receptors (SNARE proteins). Here, we describe a protocol for obtaining a highly pure culture of CGN from postnatal rats/mice and an easy procedure for their intoxication with CNT. We also illustrate handy methods to evaluate CNT activity and their inhibition.
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Affiliation(s)
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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21
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Pirazzini M, Azarnia Tehran D, Zanetti G, Rossetto O, Montecucco C. Hsp90 and Thioredoxin-Thioredoxin Reductase enable the catalytic activity of Clostridial neurotoxins inside nerve terminals. Toxicon 2017; 147:32-37. [PMID: 29111118 DOI: 10.1016/j.toxicon.2017.10.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/21/2017] [Accepted: 10/23/2017] [Indexed: 12/12/2022]
Abstract
Botulinum (BoNTs) and tetanus (TeNT) neurotoxins are the most toxic substances known and form the growing family of Clostridial neurotoxins (CNT), the etiologic agents of botulism and tetanus. CNT are composed of a metalloprotease light chain (L), linked via a disulfide bond to a heavy chain (H). H mediates the binding to nerve terminals and the membrane translocation of L into the cytosol, where its substrates, the three SNARE proteins, are localized. L translocation is accompanied by unfolding and, once delivered on the cytosolic side of the endosome membrane, it has to be reduced and reacquire the native fold to be active. The Thioredoxin-Thioredoxin Reductase system (Trx-TrxR) specifically reduces the interchain disulfide bond while the cytosolic chaperone protein Hsp90 mediates L refolding. Both steps are essential for CNT activity and their inhibition efficiently blocks the neurotoxicity in cultured neurons and mice. Trx and its reductase physically interact with Hsp90 and are loosely bound to the cytosolic side of synaptic vesicles, the organelle exploited by CNT to enter nerve terminals and wherefrom L is translocated into the cytosol. Therefore, Trx, TrxR and Hsp90 orchestrate a chaperone-redox molecular machinery that enables the catalytic activity of the L inside nerve terminals. Given the fundamental role of L reduction and refolding, this machinery represents a rational target for the development of mechanism-based antitoxins.
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Affiliation(s)
- Marco Pirazzini
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy.
| | - Domenico Azarnia Tehran
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Giulia Zanetti
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Ornella Rossetto
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Cesare Montecucco
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy; Istituto CNR di Neuroscienze, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
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22
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Bremer PT, Pellett S, Carolan JP, Tepp WH, Eubanks LM, Allen KN, Johnson EA, Janda KD. Metal Ions Effectively Ablate the Action of Botulinum Neurotoxin A. J Am Chem Soc 2017; 139:7264-7272. [PMID: 28475321 PMCID: PMC5612488 DOI: 10.1021/jacs.7b01084] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Botulinum neurotoxin serotype A (BoNT/A) causes a debilitating and potentially fatal illness known as botulism. The toxin is also a bioterrorism threat, yet no pharmacological antagonist to counteract its effects has reached clinical approval. Existing strategies to negate BoNT/A intoxication have looked to antibodies, peptides, or organic small molecules as potential therapeutics. In this work, a departure from the traditional drug discovery mindset was pursued, in which the enzyme's susceptibility to metal ions was exploited. A screen of a series of metal salts showed marked inhibitory activity of group 11 and 12 metals against the BoNT/A light chain (LC) protease. Enzyme kinetics revealed that copper (I) and (II) cations displayed noncompetitive inhibition of the LC (Ki ≈ 1 μM), while mercury (II) cations were 10-fold more potent. Crystallographic and mutagenesis studies elucidated a key binding interaction between Cys165 on BoNT/A LC and the inhibitory metals. As potential copper prodrugs, ligand-copper complexes were examined in a cell-based model and were found to prevent BoNT/A cleavage of the endogenous protein substrate, SNAP-25, even at low μM concentrations of complexes. Further investigation of the complexes suggested a bioreductive mechanism causing intracellular release of copper, which directly inhibited the BoNT/A protease. In vivo experiments demonstrated that copper (II) dithiocarbamate and bis(thiosemicarbazone) complexes could delay BoNT/A-mediated lethality in a rodent model, indicating their potential for treating the harmful effects of BoNT/A intoxication. Our studies illustrate that metals can be therapeutically viable enzyme inhibitors; moreover, enzymes that share homology with BoNT LCs may be similarly targeted with metals.
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Affiliation(s)
- Paul T. Bremer
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, USA
| | - James P. Carolan
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | - William H. Tepp
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, USA
| | - Lisa M. Eubanks
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Karen N. Allen
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA
| | - Eric A. Johnson
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, USA
| | - Kim D. Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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23
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Pirazzini M, Rossetto O, Eleopra R, Montecucco C. Botulinum Neurotoxins: Biology, Pharmacology, and Toxicology. Pharmacol Rev 2017; 69:200-235. [PMID: 28356439 PMCID: PMC5394922 DOI: 10.1124/pr.116.012658] [Citation(s) in RCA: 410] [Impact Index Per Article: 58.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The study of botulinum neurotoxins (BoNT) is rapidly progressing in many aspects.
Novel BoNTs are being discovered owing to next generation sequencing, but their
biologic and pharmacological properties remain largely unknown. The molecular
structure of the large protein complexes that the toxin forms with accessory
proteins, which are included in some BoNT type A1 and B1 pharmacological
preparations, have been determined. By far the largest effort has been dedicated to
the testing and validation of BoNTs as therapeutic agents in an ever increasing
number of applications, including pain therapy. BoNT type A1 has been also exploited
in a variety of cosmetic treatments, alone or in combination with other agents, and
this specific market has reached the size of the one dedicated to the treatment of
medical syndromes. The pharmacological properties and mode of action of BoNTs have
shed light on general principles of neuronal transport and protein-protein
interactions and are stimulating basic science studies. Moreover, the wide array of
BoNTs discovered and to be discovered and the production of recombinant BoNTs endowed
with specific properties suggest novel uses in therapeutics with increasing
disease/symptom specifity. These recent developments are reviewed here to provide an
updated picture of the biologic mechanism of action of BoNTs, of their increasing use
in pharmacology and in cosmetics, and of their toxicology.
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Affiliation(s)
- Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
| | - Roberto Eleopra
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
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Pirazzini M, Rossetto O. Challenges in searching for therapeutics against Botulinum Neurotoxins. Expert Opin Drug Discov 2017; 12:497-510. [DOI: 10.1080/17460441.2017.1303476] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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The Molecular Basis of Toxins' Interactions with Intracellular Signaling via Discrete Portals. Toxins (Basel) 2017; 9:toxins9030107. [PMID: 28300784 PMCID: PMC5371862 DOI: 10.3390/toxins9030107] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 03/02/2017] [Accepted: 03/04/2017] [Indexed: 12/20/2022] Open
Abstract
An understanding of the molecular mechanisms by which microbial, plant or animal-secreted toxins exert their action provides the most important element for assessment of human health risks and opens new insights into therapies addressing a plethora of pathologies, ranging from neurological disorders to cancer, using toxinomimetic agents. Recently, molecular and cellular biology dissecting tools have provided a wealth of information on the action of these diverse toxins, yet, an integrated framework to explain their selective toxicity is still lacking. In this review, specific examples of different toxins are emphasized to illustrate the fundamental mechanisms of toxicity at different biochemical, molecular and cellular- levels with particular consideration for the nervous system. The target of primary action has been highlighted and operationally classified into 13 sub-categories. Selected examples of toxins were assigned to each target category, denominated as portal, and the modulation of the different portal’s signaling was featured. The first portal encompasses the plasma membrane lipid domains, which give rise to pores when challenged for example with pardaxin, a fish toxin, or is subject to degradation when enzymes of lipid metabolism such as phospholipases A2 (PLA2) or phospholipase C (PLC) act upon it. Several major portals consist of ion channels, pumps, transporters and ligand gated ionotropic receptors which many toxins act on, disturbing the intracellular ion homeostasis. Another group of portals consists of G-protein-coupled and tyrosine kinase receptors that, upon interaction with discrete toxins, alter second messengers towards pathological levels. Lastly, subcellular organelles such as mitochondria, nucleus, protein- and RNA-synthesis machineries, cytoskeletal networks and exocytic vesicles are also portals targeted and deregulated by other diverse group of toxins. A fundamental concept can be drawn from these seemingly different toxins with respect to the site of action and the secondary messengers and signaling cascades they trigger in the host. While the interaction with the initial portal is largely determined by the chemical nature of the toxin, once inside the cell, several ubiquitous second messengers and protein kinases/ phosphatases pathways are impaired, to attain toxicity. Therefore, toxins represent one of the most promising natural molecules for developing novel therapeutics that selectively target the major cellular portals involved in human physiology and diseases.
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26
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Yang NJ, Chiu IM. Bacterial Signaling to the Nervous System through Toxins and Metabolites. J Mol Biol 2017; 429:587-605. [PMID: 28065740 PMCID: PMC5325782 DOI: 10.1016/j.jmb.2016.12.023] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/21/2016] [Accepted: 12/29/2016] [Indexed: 12/31/2022]
Abstract
Mammalian hosts interface intimately with commensal and pathogenic bacteria. It is increasingly clear that molecular interactions between the nervous system and microbes contribute to health and disease. Both commensal and pathogenic bacteria are capable of producing molecules that act on neurons and affect essential aspects of host physiology. Here we highlight several classes of physiologically important molecular interactions that occur between bacteria and the nervous system. First, clostridial neurotoxins block neurotransmission to or from neurons by targeting the SNARE complex, causing the characteristic paralyses of botulism and tetanus during bacterial infection. Second, peripheral sensory neurons-olfactory chemosensory neurons and nociceptor sensory neurons-detect bacterial toxins, formyl peptides, and lipopolysaccharides through distinct molecular mechanisms to elicit smell and pain. Bacteria also damage the central nervous system through toxins that target the brain during infection. Finally, the gut microbiota produces molecules that act on enteric neurons to influence gastrointestinal motility, and metabolites that stimulate the "gut-brain axis" to alter neural circuits, autonomic function, and higher-order brain function and behavior. Furthering the mechanistic and molecular understanding of how bacteria affect the nervous system may uncover potential strategies for modulating neural function and treating neurological diseases.
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Affiliation(s)
- Nicole J Yang
- Department of Microbiology and Immunobiology, Division of Immunology, Harvard Medical School, Boston, MA 02115, USA
| | - Isaac M Chiu
- Department of Microbiology and Immunobiology, Division of Immunology, Harvard Medical School, Boston, MA 02115, USA.
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27
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Carle S, Brink T, Orth JHC, Aktories K, Barth H. Auranofin Inhibits the Enzyme Activity of Pasteurella multocida Toxin PMT in Human Cells and Protects Cells from Intoxication. Toxins (Basel) 2017; 9:toxins9010032. [PMID: 28098782 PMCID: PMC5308264 DOI: 10.3390/toxins9010032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/23/2016] [Accepted: 01/10/2017] [Indexed: 11/16/2022] Open
Abstract
The AB-type protein toxin from Pasteurella multocida (PMT) contains a functionally important disulfide bond within its catalytic domain, which must be cleaved in the host cell cytosol to render the catalytic domain of PMT into its active conformation. Here, we found that the reductive potential of the cytosol of target cells, and more specifically, the activity of the thioredoxin reductase (TrxR) is crucial for this process. This was demonstrated by the strong inhibitory effect of the pharmacological TrxR inhibitor auranofin, which inhibited the intoxication of target cells with PMT, as determined by analyzing the PMT-catalyzed deamidation of GTP-binding proteins (G-proteins) in the cytosol of cells. The amount of endogenous substrate levels modified by PMT in cells pretreated with auranofin was reduced compared to cells treated with PMT alone. Auranofin had no inhibitory effect on the activity of the catalytic domain of constitutively active PMT in vitro, demonstrating that auranofin did not directly inhibit PMT activity, but interferes with the mode of action of PMT in cells. In conclusion, the results show that TrxR is crucial for the mode of action of PMT in mammalian cells, and that the drug auranofin can serve as an efficient inhibitor, which might be a starting point for novel therapeutic options against toxin-associated diseases.
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Affiliation(s)
- Stefan Carle
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, Ulm 89081, Germany.
| | - Thorsten Brink
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg 79104, Germany.
| | - Joachim H C Orth
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg 79104, Germany.
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Freiburg 79104, Germany.
- Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Freiburg 79104, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, Ulm 89081, Germany.
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28
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Azarnia Tehran D, Pirazzini M, Leka O, Mattarei A, Lista F, Binz T, Rossetto O, Montecucco C. Hsp90 is involved in the entry of clostridial neurotoxins into the cytosol of nerve terminals. Cell Microbiol 2016; 19. [DOI: 10.1111/cmi.12647] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/06/2016] [Accepted: 07/08/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Domenico Azarnia Tehran
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Marco Pirazzini
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Oneda Leka
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Andrea Mattarei
- Department of Chemical Sciences; University of Padova; Via F. Marzolo 1 35131 Padova Italy
| | - Florigio Lista
- Histology and Molecular Biology Section; Army Medical and Veterinary Research Center; Via Santo Stefano Rotondo 4 00184 Rome Italy
| | - Thomas Binz
- Medizinische Hochschule Hannover; Institut für Physiologische Chemie OE4310; 30625 Hannover Germany
| | - Ornella Rossetto
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
- National Research Institute of Neuroscience; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
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29
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Authier F, Djavaheri-Mergny M, Lorin S, Frénoy JP, Desbuquois B. Fate and action of ricin in rat liverin vivo: translocation of endocytosed ricin into cytosol and induction of intrinsic apoptosis by ricin B-chain. Cell Microbiol 2016; 18:1800-1814. [DOI: 10.1111/cmi.12621] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 12/13/2022]
Affiliation(s)
- François Authier
- Service information scientifique et technique (IST) de l'Inserm; Paris France
| | | | - Séverine Lorin
- Inserm UMR-S-1193; Université Paris-Saclay; 92296 Châtenay-Malabry France
| | - Jean-Pierre Frénoy
- CNRS UMR 8601, Centre Universitaire des Saints-Pères; Université Paris-Descartes; Paris France
| | - Bernard Desbuquois
- Inserm U 1016 and CNRS UMR 8104; Université Paris-Descartes, Institut Cochin; Paris France
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30
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Seki H, Xue S, Pellett S, Šilhár P, Johnson EA, Janda KD. Cellular Protection of SNAP-25 against Botulinum Neurotoxin/A: Inhibition of Thioredoxin Reductase through a Suicide Substrate Mechanism. J Am Chem Soc 2016; 138:5568-75. [PMID: 27070533 PMCID: PMC4881748 DOI: 10.1021/jacs.5b12929] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Botulium neurotoxins (BoNTs) are among the most lethal toxins known to man. They are comprised of seven serotypes with BoNT/A being the most deadly; yet, there is no approved therapeutic for their intoxication or one that has even advanced to clinical trials. Botulinum neurotoxicity is ultimately governed through light chain (LC) protease SNARE protein cleavage leading to a loss of neurotransmitter release. Pharmacological attempts to ablate BoNT/A intoxication have sought to either nullify cellular toxin entry or critical biochemical junctions found within its intricate mechanism of action. In these regards, reports have surfaced of nonpeptidic small molecule inhibitors, but few have demonstrated efficacy in neutralizing cellular toxicity, a key prerequisite before rodent lethality studies can be initiated. On the basis of a lead discovered in our BoNT/A cellular assay campaign, we investigated a family of N-hydroxysuccinimide inhibitors grounded upon structure activity relationship (SAR) fundamentals. Molecules stemming from this SAR exercise were theorized to be protease inhibitors. However, this proposition was overturned on the basis of extensive kinetic analysis. Unexpectedly, inhibitor data pointed to thioredoxin reductase (TrxR), an essential component required for BoNT protease translocation. Also unforeseen was the inhibitors' mechanism of action against TrxR, which was found to be brokered through a suicide-mechanism utilizing quinone methide as the inactivating element. This new series of TrxR inhibitors provides an alternative means to negate the etiological agent responsible for BoNT intoxication, the LC protease.
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Affiliation(s)
| | | | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin , 1550 Linden Drive, Madison, Wisconsin 53706, United States
| | | | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin , 1550 Linden Drive, Madison, Wisconsin 53706, United States
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31
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Williams JM, Tsai B. Intracellular trafficking of bacterial toxins. Curr Opin Cell Biol 2016; 41:51-6. [PMID: 27084982 DOI: 10.1016/j.ceb.2016.03.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 03/23/2016] [Accepted: 03/24/2016] [Indexed: 11/18/2022]
Abstract
Bacterial toxins often translocate across a cellular membrane to gain access into the host cytosol, modifying cellular components in order to exert their toxic effects. To accomplish this feat, these toxins traffic to a membrane penetration site where they undergo conformational changes essential to eject the toxin's catalytic subunit into the cytosol. In this brief review, we highlight recent findings that elucidate both the trafficking pathways and membrane translocation mechanisms of toxins that cross the plasma, endosomal, or endoplasmic reticulum (ER) membrane. These findings not only illuminate the specific nature of the host-toxin interactions during entry, but should also provide additional therapeutic strategies to prevent or alleviate the bacterial toxin-induced diseases.
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Affiliation(s)
- Jeffrey M Williams
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, MI 48109, United States
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Room 3043, Ann Arbor, MI 48109, United States.
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32
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Wild E, Bonifas U, Klimek J, Trösemeier JH, Krämer B, Kegel B, Behrensdorf-Nicol HA. In vitro potency determination of botulinum neurotoxin B based on its receptor-binding and proteolytic characteristics. Toxicol In Vitro 2016; 34:97-104. [PMID: 27032463 DOI: 10.1016/j.tiv.2016.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/21/2016] [Indexed: 01/09/2023]
Abstract
Botulinum neurotoxins (BoNTs) are the most potent toxins known. However, the paralytic effect caused by BoNT serotypes A and B is taken advantage of to treat different forms of dystonia and in cosmetic procedures. Due to the increasing areas of application, the demand for BoNTs A and B is rising steadily. Because of the high toxicity, it is mandatory to precisely determine the potency of every produced BoNT batch, which is usually accomplished by performing toxicity testing (LD50 test) in mice. Here we describe an alternative in vitro assay for the potency determination of the BoNT serotype B. In this assay, the toxin is first bound to its specific receptor molecules. After the proteolytic subunit of the toxin has been released and activated by chemical reduction, it is exposed to synaptobrevin, its substrate protein. Finally the proteolytic cleavage is quantified by an antibody-mediated detection of the neoepitope, reaching a detection limit below 0.1mouseLD50/ml. Thus, the assay, named BoNT/B binding and cleavage assay (BoNT/B BINACLE), takes into account the binding as well as the protease function of the toxin, thereby measuring its biological activity.
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Affiliation(s)
- Emina Wild
- Veterinary Medicine Division, Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicals), Langen, Germany
| | - Ursula Bonifas
- Veterinary Medicine Division, Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicals), Langen, Germany
| | - Jolanta Klimek
- Veterinary Medicine Division, Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicals), Langen, Germany
| | - Jan-Hendrik Trösemeier
- Microbiology Division, Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicals), Langen, Germany; Molecular Bioinformatics, Institute of Computer Science, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
| | - Beate Krämer
- Veterinary Medicine Division, Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicals), Langen, Germany
| | - Birgit Kegel
- Veterinary Medicine Division, Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicals), Langen, Germany
| | - Heike A Behrensdorf-Nicol
- Veterinary Medicine Division, Paul-Ehrlich-Institut (Federal Institute for Vaccines and Biomedicals), Langen, Germany.
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33
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Azarnia Tehran D, Zanetti G, Leka O, Lista F, Fillo S, Binz T, Shone CC, Rossetto O, Montecucco C, Paradisi C, Mattarei A, Pirazzini M. A Novel Inhibitor Prevents the Peripheral Neuroparalysis of Botulinum Neurotoxins. Sci Rep 2015; 5:17513. [PMID: 26670952 PMCID: PMC4680858 DOI: 10.1038/srep17513] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 10/30/2015] [Indexed: 11/17/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) form a large class of potent and deadly neurotoxins. Given their growing number, it is of paramount importance to discover novel inhibitors targeting common steps of their intoxication process. Recently, EGA was shown to inhibit the action of bacterial toxins and viruses exhibiting a pH-dependent translocation step in mammalian cells, by interfering with their entry route. As BoNTs act in the cytosol of nerve terminals, the entry into an appropriate compartment wherefrom they translocate the catalytic moiety is essential for toxicity. Herein we propose an optimized procedure to synthesize EGA and we show that, in vitro, it prevents the neurotoxicity of different BoNT serotypes by interfering with their trafficking. Furthermore, in mice, EGA mitigates botulism symptoms induced by BoNT/A and significantly decreases the lethality of BoNT/B and BoNT/D. This opens the possibility of using EGA as a lead compound to develop novel inhibitors of botulinum neurotoxins.
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Affiliation(s)
| | - Giulia Zanetti
- Department of Biomedical Sciences, Via U. Bassi 58/B, 35121, Padova, Italy
| | - Oneda Leka
- Department of Biomedical Sciences, Via U. Bassi 58/B, 35121, Padova, Italy
| | - Florigio Lista
- Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Roma, Italy
| | - Silvia Fillo
- Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Roma, Italy
| | - Thomas Binz
- Institut für Biochemie, OE 4310, Medizinische Hochschule Hannover, 30623 Hannover, Germany
| | - Clifford C. Shone
- Public Health England, Porton Down, Salisbury, Wiltshire, SP4 OJG, UK
| | - Ornella Rossetto
- Department of Biomedical Sciences, Via U. Bassi 58/B, 35121, Padova, Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences, Via U. Bassi 58/B, 35121, Padova, Italy
- Italian National Research Council Institute of Neuroscience, University of Padova, Via U. Bassi 58/B, 35121, Padova, Italy
| | - Cristina Paradisi
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Andrea Mattarei
- Department of Chemical Sciences, University of Padova, Via F. Marzolo 1, 35131 Padova, Italy
| | - Marco Pirazzini
- Department of Biomedical Sciences, Via U. Bassi 58/B, 35121, Padova, Italy
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34
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Rossetto O, Pirazzini M, Montecucco C. Current gaps in basic science knowledge of botulinum neurotoxin biological actions. Toxicon 2015; 107:59-63. [DOI: 10.1016/j.toxicon.2015.07.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 07/01/2015] [Indexed: 12/27/2022]
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35
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Zuverink M, Barbieri JT. From GFP to β-lactamase: advancing intact cell imaging for toxins and effectors. Pathog Dis 2015; 73:ftv097. [PMID: 26500183 DOI: 10.1093/femspd/ftv097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2015] [Indexed: 11/13/2022] Open
Abstract
Canonical reporters such as green fluorescent protein (GFP) and luciferase have assisted researchers in probing cellular pathways and processes. Prior research in pathogenesis depended on sensitivity of biochemical and biophysical techniques to identify effectors and elucidate entry mechanisms. Recently, the β-lactamase (βlac) reporter system has advanced toxin and effector reporting by permitting measurement of βlac delivery into the cytosol or host βlac expression in intact cells. βlac measurement in cells was facilitated by the development of the fluorogenic substrate, CCF2-AM, to identify novel effectors, target cells, and domains involved in bacterial pathogenesis. The assay is also adaptable for high-throughput screening of small molecule inhibitors against toxins, providing information on mechanism and potential therapeutic agents. The versatility and limitations of the βlac reporter system as applied to toxins and effectors are discussed in this review.
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Affiliation(s)
- Madison Zuverink
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI 53226, USA
| | - Joseph T Barbieri
- Medical College of Wisconsin, Microbiology and Molecular Genetics, Milwaukee, WI 53226, USA
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36
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Zanetti G, Azarnia Tehran D, Pirazzini M, Binz T, Shone CC, Fillo S, Lista F, Rossetto O, Montecucco C. Inhibition of botulinum neurotoxins interchain disulfide bond reduction prevents the peripheral neuroparalysis of botulism. Biochem Pharmacol 2015; 98:522-30. [PMID: 26449594 DOI: 10.1016/j.bcp.2015.09.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 09/29/2015] [Indexed: 12/18/2022]
Abstract
Botulinum neurotoxins (BoNTs) form a growing family of metalloproteases with a unique specificity either for VAMP, SNAP25 or syntaxin. The BoNTs are grouped in seven different serotypes indicated by letters from A to G. These neurotoxins enter the cytosol of nerve terminals via a 100 kDa chain which binds to the presynaptic membrane and assists the translocation of a 50 kDa metalloprotease chain. These two chains are linked by a single disulfide bridge which plays an essential role during the entry of the metalloprotease chain in the cytosol, but thereafter it has to be reduced to free the proteolytic activity. Its reduction is mediated by thioredoxin which is continuously regenerated by its reductase. Here we show that inhibitors of thioredoxin reductase or of thioredoxin prevent the specific proteolysis of VAMP by the four VAMP-specific BoNTs: type B, D, F and G. These compounds are effective not only in primary cultures of neurons, but also in preventing the in vivo mouse limb neuroparalysis. In addition, one of these inhibitors, Ebselen, largely protects mice from the death caused by a systemic injection. Together with recent results obtained with BoNTs specific for SNAP25 and syntaxin, the present data demonstrate the essential role of the thioredoxin-thioredoxin reductase system in reducing the interchain disulfide during the nerve intoxication mechanism of all serotypes. Therefore its inhibitors should be considered for a possible use to prevent botulism and for treating infant botulism.
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Affiliation(s)
- Giulia Zanetti
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Domenico Azarnia Tehran
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Marcon Pirazzini
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Thomas Binz
- Institut für Biochemie, OE 4310, Medizinische Hochschule Hannover, 30623 Hannover, Germany
| | - Clifford C Shone
- Public Health England, Porton Down, Salisbury, Wiltshire SP4 OJG, UK
| | - Silvia Fillo
- Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy
| | - Florigio Lista
- Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy
| | - Ornella Rossetto
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Cesare Montecucco
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy; Istituto CNR di Neuroscienze, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy.
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37
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On the translocation of botulinum and tetanus neurotoxins across the membrane of acidic intracellular compartments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:467-74. [PMID: 26307528 DOI: 10.1016/j.bbamem.2015.08.014] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 08/04/2015] [Accepted: 08/17/2015] [Indexed: 01/25/2023]
Abstract
Tetanus and botulinum neurotoxins are produced by anaerobic bacteria of the genus Clostridium and are the most poisonous toxins known, with 50% mouse lethal dose comprised within the range of 0.1-few nanograms per Kg, depending on the individual toxin. Botulinum neurotoxins are similarly toxic to humans and can therefore be considered for potential use in bioterrorism. At the same time, their neurospecificity and reversibility of action make them excellent therapeutics for a growing and heterogeneous number of human diseases that are characterized by a hyperactivity of peripheral nerve terminals. The complete crystallographic structure is available for some botulinum toxins, and reveals that they consist of four domains functionally related to the four steps of their mechanism of neuron intoxication: 1) binding to specific receptors of the presynaptic membrane; 2) internalization via endocytic vesicles; 3) translocation across the membrane of endocytic vesicles into the neuronal cytosol; 4) catalytic activity of the enzymatic moiety directed towards the SNARE proteins. Despite the many advances in understanding the structure-mechanism relationship of tetanus and botulinum neurotoxins, the molecular events involved in the translocation step have been only partially elucidated. Here we will review recent advances that have provided relevant insights on the process and discuss possible models that can be experimentally tested. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.
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38
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Kim DW, Lee SK, Ahnn J. Botulinum Toxin as a Pain Killer: Players and Actions in Antinociception. Toxins (Basel) 2015; 7:2435-53. [PMID: 26134255 PMCID: PMC4516922 DOI: 10.3390/toxins7072435] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 06/19/2015] [Accepted: 06/23/2015] [Indexed: 11/17/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) have been widely used to treat a variety of clinical ailments associated with pain. The inhibitory action of BoNTs on synaptic vesicle fusion blocks the releases of various pain-modulating neurotransmitters, including glutamate, substance P (SP), and calcitonin gene-related peptide (CGRP), as well as the addition of pain-sensing transmembrane receptors such as transient receptor potential (TRP) to neuronal plasma membrane. In addition, growing evidence suggests that the analgesic and anti-inflammatory effects of BoNTs are mediated through various molecular pathways. Recent studies have revealed that the detailed structural bases of BoNTs interact with their cellular receptors and SNAREs. In this review, we discuss the molecular and cellular mechanisms related to the efficacy of BoNTs in alleviating human pain and insights on engineering the toxins to extend therapeutic interventions related to nociception.
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Affiliation(s)
- Dong-Wan Kim
- Department of Life Science, School of Natural Science, Hanyang University, Seoul 133-791, Korea.
- BK21 PLUS Life Science for BioDefense Research (BDR) Team, Hanyang University, Seoul 133-791, Korea.
| | - Sun-Kyung Lee
- Department of Life Science, School of Natural Science, Hanyang University, Seoul 133-791, Korea.
- BK21 PLUS Life Science for BioDefense Research (BDR) Team, Hanyang University, Seoul 133-791, Korea.
- The Research Institute for Natural Science, Hanyang University, Seoul 133-791, Korea.
| | - Joohong Ahnn
- Department of Life Science, School of Natural Science, Hanyang University, Seoul 133-791, Korea.
- BK21 PLUS Life Science for BioDefense Research (BDR) Team, Hanyang University, Seoul 133-791, Korea.
- The Research Institute for Natural Science, Hanyang University, Seoul 133-791, Korea.
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Pirazzini M, Azarnia Tehran D, Zanetti G, Lista F, Binz T, Shone CC, Rossetto O, Montecucco C. The thioredoxin reductase--Thioredoxin redox system cleaves the interchain disulphide bond of botulinum neurotoxins on the cytosolic surface of synaptic vesicles. Toxicon 2015; 107:32-6. [PMID: 26130523 DOI: 10.1016/j.toxicon.2015.06.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 06/23/2015] [Indexed: 11/16/2022]
Abstract
Botulinum neurotoxins (BoNTs) are Janus toxins, as they are at the same time the most deadly substances known and one of the safest drugs used in human therapy. They specifically block neurotransmission at peripheral nerves through the proteolysis of SNARE proteins, i.e. the essential proteins which are the core of the neuroexocytosis machinery. Even if BoNTs are traditionally known as seven main serotypes, their actual number is much higher as each serotype exists in many different subtypes, with individual biological properties and little antigenic relations. Since BoNTs can be used as biological weapons, and the only currently available therapy is based on immunological approaches, the existence of so many different subtypes is a major safety problem. Nevertheless, all BoNT isoforms are structurally similar and intoxicate peripheral nerve endings via a conserved mechanism. They consist of two chains linked by a unique disulphide bond which must be reduced to enable their toxicity. We found that thioredoxin 1 and its reductase compose the cell redox system responsible for this reduction, and its inhibition via specific chemicals significantly reduces BoNTs activity, in vitro as well as in vivo. Such molecules can be considered as lead compounds for the development of pan-inhibitors.
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Affiliation(s)
- Marco Pirazzini
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy.
| | - Domenico Azarnia Tehran
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Giulia Zanetti
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Florigio Lista
- Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy
| | - Thomas Binz
- Institut fur Biochemie, Medizinische Hochschule Hannover, 30623 Hannover, Germany
| | - Clifford C Shone
- Public Health England, Porton Down, Salisbury, Wiltshire, SP4 OJG, UK
| | - Ornella Rossetto
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Cesare Montecucco
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy; Istituto CNR di Neuroscienze, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
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Schnell L, Dmochewitz-Kück L, Feigl P, Montecucco C, Barth H. Thioredoxin reductase inhibitor auranofin prevents membrane transport of diphtheria toxin into the cytosol and protects human cells from intoxication. Toxicon 2015; 116:23-8. [PMID: 25911959 DOI: 10.1016/j.toxicon.2015.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 04/21/2015] [Accepted: 04/23/2015] [Indexed: 11/16/2022]
Abstract
During cellular uptake, diphtheria toxin delivers its catalytic domain DTA from acidified endosomes into the cytosol, which requires reduction of the disulfide linking DTA to the transport domain. In vitro, thioredoxin reduces this disulfide and thioredoxin reductase (TrxR) is part of a cytosolic complex facilitating DTA-translocation. We found that the TrxR-specific inhibitor auranofin prevented DTA delivery into the cytosol and intoxication of HeLa cells with diphtheria toxin, offering perspectives for novel pharmacological strategies against diphtheria.
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Affiliation(s)
- Leonie Schnell
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Germany
| | | | - Peter Feigl
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Germany
| | | | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Germany.
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A Heterologous Reporter Defines the Role of the Tetanus Toxin Interchain Disulfide in Light-Chain Translocation. Infect Immun 2015; 83:2714-24. [PMID: 25895970 DOI: 10.1128/iai.00477-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 04/13/2015] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) and tetanus toxin (TeNT) are the most potent toxins for humans and elicit unique pathologies due to their ability to traffic within motor neurons. BoNTs act locally within motor neurons to elicit flaccid paralysis, while retrograde TeNT traffics to inhibitory neurons within the central nervous system (CNS) to elicit spastic paralysis. BoNT and TeNT are dichain proteins linked by an interchain disulfide bond comprised of an N-terminal catalytic light chain (LC) and a C-terminal heavy chain (HC) that encodes an LC translocation domain (HCT) and a receptor-binding domain (HCR). LC translocation is the least understood property of toxin action, but it involves low pH, proteolysis, and an intact interchain disulfide bridge. Recently, Pirazzini et al. (FEBS Lett 587:150-155, 2013, http://dx.doi.org/10.1016/j.febslet.2012.11.007) observed that inhibitors of thioredoxin reductase (TrxR) blocked TeNT and BoNT action in cerebellar granular neurons. In the current study, an atoxic TeNT LC translocation reporter was engineered by fusing β-lactamase to the N terminus of TeNT [βlac-TeNT(RY)] to investigate LC translocation in primary cortical neurons and Neuro-2a cells. βlac-TeNT(RY) retained the interchain disulfide bond, showed ganglioside-dependent binding to neurons, required acidification to promote βlac translocation, and was sensitive to auranofin, an inhibitor of thioredoxin reductase. Mutation of βlac-TeNT(RY) at C439S and C467S eliminated the interchain disulfide bond and inhibited βlac translocation. These data support the requirement of an intact interchain disulfide for LC translocation and imply that disulfide reduction is a prerequisite for LC delivery into the host cytosol. The data also support a model that LC translocation proceeds from the C to the N terminus. βlac-TeNT(RY) is the first reporter system to measure translocation by an AB single-chain toxin in intact cells.
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Abstract
The rapidly growing number of botulinum neurotoxin sequences poses the problem of the possible evolutionary significance of the variability of these superpotent neurotoxins for toxin-producing Clostridium species. To progress in the understanding of this remarkable phenomenon, we suggest that researchers should (i) abandon an anthropocentric view of these neurotoxins as human botulism-causing agents or as human therapeutics, (ii) begin to investigate in depth the role of botulinum neurotoxins in animal botulism in the wilderness, and (iii) devote large efforts to next-generation sequencing of soil samples to identify novel botulinum neurotoxins. In order to compare the fitness of the different toxins, we suggest that assays of all the steps from toxin production to animal death should be performed.
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Thioredoxin and its reductase are present on synaptic vesicles, and their inhibition prevents the paralysis induced by botulinum neurotoxins. Cell Rep 2014; 8:1870-1878. [PMID: 25220457 DOI: 10.1016/j.celrep.2014.08.017] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/29/2014] [Accepted: 08/07/2014] [Indexed: 11/23/2022] Open
Abstract
Botulinum neurotoxins consist of a metalloprotease linked via a conserved interchain disulfide bond to a heavy chain responsible for neurospecific binding and translocation of the enzymatic domain in the nerve terminal cytosol. The metalloprotease activity is enabled upon disulfide reduction and causes neuroparalysis by cleaving the SNARE proteins. Here, we show that the thioredoxin reductase-thioredoxin protein disulfide-reducing system is present on synaptic vesicles and that it is functional and responsible for the reduction of the interchain disulfide of botulinum neurotoxin serotypes A, C, and E. Specific inhibitors of thioredoxin reductase or thioredoxin prevent intoxication of cultured neurons in a dose-dependent manner and are also very effective inhibitors of the paralysis of the neuromuscular junction. We found that this group of inhibitors of botulinum neurotoxins is very effective in vivo. Most of them are nontoxic and are good candidates as preventive and therapeutic drugs for human botulism.
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Klein PM, Wagner E. Bioreducible polycations as shuttles for therapeutic nucleic acid and protein transfection. Antioxid Redox Signal 2014; 21:804-17. [PMID: 24219092 PMCID: PMC4098974 DOI: 10.1089/ars.2013.5714] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 11/12/2013] [Indexed: 01/05/2023]
Abstract
SIGNIFICANCE Nucleic acids such as gene-encoding DNAs, gene-silencing small interfering RNAs, or recombinant proteins addressing intracellular molecular targets present a major new therapeutic modality, provided efficient solutions for intracellular delivery can be found. The different physiological redox environments inside and outside the cell can be utilized for optimizing the involved transport processes. RECENT ADVANCES Intracellular delivery of nucleic acids or proteins requires dynamic carriers that discriminate between different cellular locations. Bioreducible cationic polymers can package their therapeutic cargo stably in the extracellular environment, but sense the reducing intracellular cytosolic environment. Based on disulfide cleavage, carriers are degraded into biocompatible fragments and release the cargo in functional form. Disulfide linkages between oligocations, between the carrier and the cargo, or spatial caging of complexed cargo by disulfides have been pursued, with polymers or precise sequence-defined peptides and oligomers. CRITICAL ISSUES A quantitative knowledge of the bioreductive capacities within different biological compartments and the involved cellular reduction processes would be greatly helpful for improved carriers with disulfides cleaved within the right compartment at the right time. FUTURE DIRECTIONS Novel designs of multifunctional nanocarriers will incorporate macromolecular disulfide entry mechanisms previously optimized by natural evolution of toxins and viruses. In addition to extracellular stabilization and intracellular disassembly, tuned disulfides will contribute to deshielding at the cell surface, or translocation from intracellular compartments to the cytosol.
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Affiliation(s)
- Philipp M. Klein
- Pharmaceutical Biotechnology, Center for System-Based Drug Research, Ludwig-Maximilians-University, Munich, Germany
- Center for Nanoscience (CeNS), Ludwig-Maximilians-University, Munich, Germany
| | - Ernst Wagner
- Pharmaceutical Biotechnology, Center for System-Based Drug Research, Ludwig-Maximilians-University, Munich, Germany
- Center for Nanoscience (CeNS), Ludwig-Maximilians-University, Munich, Germany
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Anniballi F, Lonati D, Fiore A, Auricchio B, De Medici D, Locatelli CA. New targets in the search for preventive and therapeutic agents for botulism. Expert Rev Anti Infect Ther 2014; 12:1075-86. [PMID: 25089560 DOI: 10.1586/14787210.2014.945917] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Botulism is a severe neuroparalytic disease resulting from exposure to one of the most poisonous toxins to humans. Because of this high potency and the use of toxins as biological weapons, botulism is a public health concern and each case represents an emergency. Current therapy involves respiratory supportive care and anti-toxins administration. As a preventive measure, vaccination against toxins represents an effective strategy but is undesirable due the rarity of botulism and the effectiveness of toxins in treating several neuromuscular disorders. This paper summarizes the current issues in botulism treatment and prevention, highlighting the challenge for future researches.
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Affiliation(s)
- Fabrizio Anniballi
- Department of Veterinary Public Health and Food Safety, National Reference Centre for Botulism, Istituto Superiore di Sanità, Viale Regina Elena, 299 - 00161 Rome, Italy
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Rossetto O, Pirazzini M, Montecucco C. Botulinum neurotoxins: genetic, structural and mechanistic insights. Nat Rev Microbiol 2014; 12:535-49. [PMID: 24975322 DOI: 10.1038/nrmicro3295] [Citation(s) in RCA: 378] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Botulinum neurotoxins (BoNTs) are produced by anaerobic bacteria of the genus Clostridium and cause a persistent paralysis of peripheral nerve terminals, which is known as botulism. Neurotoxigenic clostridia belong to six phylogenetically distinct groups and produce more than 40 different BoNT types, which inactivate neurotransmitter release owing to their metalloprotease activity. In this Review, we discuss recent studies that have improved our understanding of the genetics and structure of BoNT complexes. We also describe recent insights into the mechanisms of BoNT entry into the general circulation, neuronal binding, membrane translocation and neuroparalysis.
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Affiliation(s)
- Ornella Rossetto
- 1] Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy. [2] National Research Council Institute of Neuroscience, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy. [3]
| | - Marco Pirazzini
- 1] Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy. [2] National Research Council Institute of Neuroscience, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy. [3]
| | - Cesare Montecucco
- 1] Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy. [2] National Research Council Institute of Neuroscience, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy
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Friedman M, Rasooly R. Review of the inhibition of biological activities of food-related selected toxins by natural compounds. Toxins (Basel) 2013; 5:743-75. [PMID: 23612750 PMCID: PMC3705290 DOI: 10.3390/toxins5040743] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 04/05/2013] [Accepted: 04/16/2013] [Indexed: 11/17/2022] Open
Abstract
There is a need to develop food-compatible conditions to alter the structures of fungal, bacterial, and plant toxins, thus transforming toxins to nontoxic molecules. The term 'chemical genetics' has been used to describe this approach. This overview attempts to survey and consolidate the widely scattered literature on the inhibition by natural compounds and plant extracts of the biological (toxicological) activity of the following food-related toxins: aflatoxin B1, fumonisins, and ochratoxin A produced by fungi; cholera toxin produced by Vibrio cholerae bacteria; Shiga toxins produced by E. coli bacteria; staphylococcal enterotoxins produced by Staphylococcus aureus bacteria; ricin produced by seeds of the castor plant Ricinus communis; and the glycoalkaloid α-chaconine synthesized in potato tubers and leaves. The reduction of biological activity has been achieved by one or more of the following approaches: inhibition of the release of the toxin into the environment, especially food; an alteration of the structural integrity of the toxin molecules; changes in the optimum microenvironment, especially pH, for toxin activity; and protection against adverse effects of the toxins in cells, animals, and humans (chemoprevention). The results show that food-compatible and safe compounds with anti-toxin properties can be used to reduce the toxic potential of these toxins. Practical applications and research needs are suggested that may further facilitate reducing the toxic burden of the diet. Researchers are challenged to (a) apply the available methods without adversely affecting the nutritional quality, safety, and sensory attributes of animal feed and human food and (b) educate food producers and processors and the public about available approaches to mitigating the undesirable effects of natural toxins that may present in the diet.
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Affiliation(s)
- Mendel Friedman
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, USDA, Albany, CA 94710, USA
| | - Reuven Rasooly
- Foodborne Contaminants Research Unit, Agricultural Research Service, USDA, Albany, CA 94710, USA; E-Mail:
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