scholarly journals Special Delivery: Potential Mechanisms of Botulinum Neurotoxin Uptake and Trafficking within Motor Nerve Terminals

2020 ◽  
Vol 21 (22) ◽  
pp. 8715
Author(s):  
Brittany M. Winner ◽  
Skylar M. L. Bodt ◽  
Patrick M. McNutt
Keyword(s):  
Motor Neurons ◽  
Botulinum Neurotoxin ◽  
Motor Nerve ◽  
Snare Proteins ◽  
Vesicle Recycling ◽  
Release Of Acetylcholine ◽  
Botulinum Neurotoxins ◽  
Protein Toxins ◽  
Molecular Toxicity ◽  
Presynaptic Proteins

Botulinum neurotoxins (BoNTs) are highly potent, neuroparalytic protein toxins that block the release of acetylcholine from motor neurons and autonomic synapses. The unparalleled toxicity of BoNTs results from the highly specific and localized cleavage of presynaptic proteins required for nerve transmission. Currently, the only pharmacotherapy for botulism is prophylaxis with antitoxin, which becomes progressively less effective as symptoms develop. Treatment for symptomatic botulism is limited to supportive care and artificial ventilation until respiratory function spontaneously recovers, which can take weeks or longer. Mechanistic insights into intracellular toxin behavior have progressed significantly since it was shown that toxins exploit synaptic endocytosis for entry into the nerve terminal, but fundamental questions about host-toxin interactions remain unanswered. Chief among these are mechanisms by which BoNT is internalized into neurons and trafficked to sites of molecular toxicity. Elucidating how receptor-bound toxin is internalized and conditions under which the toxin light chain engages with target SNARE proteins is critical for understanding the dynamics of intoxication and identifying novel therapeutics. Here, we discuss the implications of newly discovered modes of synaptic vesicle recycling on BoNT uptake and intraneuronal trafficking.

scholarly journals Generation of High-Titer Neutralizing Antibodies against Botulinum Toxins A, B, and E by DNA Electrotransfer

2009 ◽  
Vol 77 (5) ◽  
pp. 2221-2229 ◽  
Author(s):  
C. Trollet ◽  
Y. Pereira ◽  
A. Burgain ◽  
E. Litzler ◽  
M. Mezrahi ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Cellular Localization ◽  
Botulinum Neurotoxin ◽  
High Titer ◽  
Efficient Production ◽  
Dna Encoding ◽  
Chain Fragment ◽  
Release Of Acetylcholine ◽  
Botulinum Neurotoxins ◽  
New Strategies

ABSTRACT Botulinum neurotoxins are known to be among the most toxic known substances. They produce severe paralysis by preventing the release of acetylcholine at the neuromuscular junction. Thus, new strategies for efficient production of safe and effective anti-botulinum neurotoxin antisera have been a high priority. Here we describe the use of DNA electrotransfer into the skeletal muscle to enhance antiserum titers against botulinum toxin serotypes A, B, and E in mice. We treated animals with codon-optimized plasmid DNA encoding the nontoxic but highly immunogenic C-terminal heavy chain fragment of the toxin. By employing both codon optimization and the electrotransfer procedure, the immune response and corresponding neutralizing antiserum titers were markedly increased. The cellular localization of the antigen and the immunization regimens were also shown to increase neutralizing titers to >100 IU/ml. This study demonstrates that DNA electrotransfer is an effective procedure for raising neutralizing antiserum titers to remarkably high levels.

scholarly journals Mechanisms of clostridial neurotoxin binding and entry

2016 ◽  
Author(s):  
◽  
Joshua R. Burns
Keyword(s):  
Synaptic Vesicle ◽  
Motor Neurons ◽  
Heavy Chain ◽  
Snare Proteins ◽  
Single Chain ◽  
Tetanus Neurotoxin ◽  
Vesicle Exocytosis ◽  
Botulinum Neurotoxins ◽  
Clostridial Neurotoxin ◽  
Axonal Trafficking

The botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) make up the clostridial neurotoxin (CNT) family. The CNTs are produced by Clostridium botulinum and Clostridum tetani respectively, and are the most potent human protein toxins. Eight CNT family members have been identified: seven botulinum neurotoxins (A-G) and tetanus neurotoxin (TeNT). Intoxication with BoNT is largely restricted to peripheral motor neurons, and results in flaccid paralysis. TeNT is sorted into a retrograde axonal trafficking pathway, transported to the central nervous system, and causes spastic paralysis. The CNTs are typical AB toxins. They are secreted as ~150 kDa single chain proteins that undergo processing to produce a disulfide linked, dichain active form. The “A” or active domain is ~50 kDa zinc dependent protease, also known as the light chain (LC), that inhibits synaptic vesicle fusion with the plasma membrane through cleavage of soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) proteins. LCs cleave one of three neuronal SNARE proteins, preventing synaptic vesicle exocytosis. The “B” subunit is ~100 kDa, and contains a heavy chain translocation domain (HCT) and heavy chain receptor binding domain (HCR). Through an unclear mechanism, the HCT undergoes a conformational change upon acidification and forms pH dependent channels, facilitating transport of the LC into the neuronal cytosol. The HCR binds neuronal receptors on the presynaptic membrane of α-motor neurons. In order to explain the neuronal specificity of the CNTs, a dual receptor model was put forward. One co-receptor is ganglioside, a glycosphingolipid with a carbohydrate backbone decorated with sialic acids and a sphingolipid anchor. To satisfy the coreceptor model, the CNTs bind either a resident synaptic vesicle protein or a second ganglioside. The focus of this work was to examine mechanisms of CNT binding and translocation to better understand CNT pathogenesis. Special emphasis was placed on understanding the ganglioside binding interactions in retrograde axonal trafficking, BoNT/A1 and A2 subtype specific ganglioside interactions, and the role of receptor contributions in CNT translocation. Improving our understanding of basic mechanisms of CNT pathogenesis, including binding, entry, and translocation we can improve inhibitor designs, vaccine development, and further CNT platforms for pharmaceutical development.

scholarly journals Synaptotagmins I and II mediate entry of botulinum neurotoxin B into cells

2003 ◽  
Vol 162 (7) ◽  
pp. 1293-1303 ◽  
Author(s):  
Min Dong ◽  
David A. Richards ◽  
Michael C. Goodnough ◽  
William H. Tepp ◽  
Eric A. Johnson ◽  
...  
Keyword(s):  
Pc12 Cells ◽  
Neurotransmitter Release ◽  
Botulinum Neurotoxin ◽  
Motor Nerve ◽  
Secretory Vesicle ◽  
Loss Of Function ◽  
Protein Receptors ◽  
Botulinum Neurotoxins ◽  
Protein Components ◽  
Activity Dependent

Botulinum neurotoxins (BoNTs) cause botulism by entering neurons and cleaving proteins that mediate neurotransmitter release; disruption of exocytosis results in paralysis and death. The receptors for BoNTs are thought to be composed of both proteins and gangliosides; however, protein components that mediate toxin entry have not been identified. Using gain-of-function and loss-of-function approaches, we report here that the secretory vesicle proteins, synaptotagmins (syts) I and II, mediate the entry of BoNT/B (but not BoNT/A or E) into PC12 cells. Further, we demonstrate that BoNT/B entry into PC12 cells and rat diaphragm motor nerve terminals was activity dependent and can be blocked using fragments of syt II that contain the BoNT/B-binding domain. Finally, we show that syt II fragments, in conjunction with gangliosides, neutralized BoNT/B in intact mice. These findings establish that syts I and II can function as protein receptors for BoNT/B.

scholarly journals Botulinum Toxin in Pediatric Neurology

2015 ◽  
Vol 2 ◽  
pp. 2333794X1559014
Author(s):  
Eman M. I. Moawad ◽  
Enas Abdallah Ali Abdallah
Keyword(s):  
Botulinum Toxin ◽  
Neurological Disorders ◽  
Botulinum Neurotoxin ◽  
Current Data ◽  
Presynaptic Membrane ◽  
Pain Syndromes ◽  
Release Of Acetylcholine ◽  
Botulinum Neurotoxins ◽  
Neurological Conditions ◽  
Spore Forming Bacteria

Botulinum neurotoxins are natural molecules produced by anaerobic spore-forming bacteria called Clostradium boltulinum. The toxin has a peculiar mechanism of action by preventing the release of acetylcholine from the presynaptic membrane. Consequently, it has been used in the treatment of various neurological conditions related to muscle hyperactivity and/or spasticity. Also, it has an impact on the autonomic nervous system by acting on smooth muscle, leading to its use in the management of pain syndromes. The use of botulinum toxin in children separate from adults has received very little attention in the literature. This review presents the current data on the use of botulinum neurotoxin to treat various neurological disorders in children.

scholarly journals Targeted delivery into motor nerve terminals of inhibitors for SNARE-cleaving proteases via liposomes coupled to an atoxic botulinum neurotoxin

FEBS Journal ◽  
2012 ◽  
Vol 279 (14) ◽  
pp. 2555-2567 ◽  
Author(s):  
Om P. Edupuganti ◽  
Saak V. Ovsepian ◽  
Jiafu Wang ◽  
Tomas H. Zurawski ◽  
James J. Schmidt ◽  
...  
Keyword(s):  
Targeted Delivery ◽  
Botulinum Neurotoxin ◽  
Motor Nerve ◽  
Nerve Terminals ◽  
Motor Nerve Terminals

scholarly journals Variations in the Botulinum Neurotoxin Binding Domain and the Potential for Novel Therapeutics

Toxins ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 421 ◽  
Author(s):  
Jonathan Davies ◽  
Sai Liu ◽  
K. Acharya
Keyword(s):  
Botulinum Neurotoxin ◽  
Neuronal Cell ◽  
Binding Domain ◽  
Novel Therapeutics ◽  
Specific Targeting ◽  
Zinc Metalloprotease ◽  
Botulinum Neurotoxins ◽  
Translocation Domain ◽  
Subtype Differences

Botulinum neurotoxins (BoNTs) are categorised into immunologically distinct serotypes BoNT/A to /G). Each serotype can also be further divided into subtypes based on differences in amino acid sequence. BoNTs are ~150 kDa proteins comprised of three major functional domains: an N-terminal zinc metalloprotease light chain (LC), a translocation domain (HN), and a binding domain (HC). The HC is responsible for targeting the BoNT to the neuronal cell membrane, and each serotype has evolved to bind via different mechanisms to different target receptors. Most structural characterisations to date have focussed on the first identified subtype within each serotype (e.g., BoNT/A1). Subtype differences within BoNT serotypes can affect intoxication, displaying different botulism symptoms in vivo, and less emphasis has been placed on investigating these variants. This review outlines the receptors for each BoNT serotype and describes the basis for the highly specific targeting of neuronal cell membranes. Understanding receptor binding is of vital importance, not only for the generation of novel therapeutics but also for understanding how best to protect from intoxication.

scholarly journals Botulism (type A) in a horse - case report

2016 ◽  
Vol 85 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Sevim Kasap ◽  
Hasan Batmaz ◽  
Meric Kocaturk ◽  
Frank Gessler ◽  
Serkan Catık ◽  
...  
Keyword(s):  
Botulinum Neurotoxin ◽  
Clinical Signs ◽  
Type A ◽  
Serum Samples ◽  
Specific Antibodies ◽  
Thoroughbred Horse ◽  
Botulinum Neurotoxin Type A ◽  
Botulinum Neurotoxins ◽  
First Time ◽  
Colonic Content

This paper presents the case of a six year-old, male, thoroughbred horse with clinical signs of inappetence, weakness, and incoordination when walking. Clinical examination showed that the horse staggered and leaned to the left side. Feedstuff was present inside and around its mouth. Salivation was increased and there was no reflex at the palpebrae and tongue. The horse had difficulty swallowing and the tone of its tail was reduced. Botulism was diagnosed based on the clinical signs. Antibiotic (ceftiofur) and fluid-electrolyte treatment was commenced. Next day, neostigmin was added to the horse’s treatment, and it became recumbent. The horse’s palpebral, tongue and tail reflexes returned partially after neostigmine methylsulphate treatment on the same day and it stood up on day four. However, it could not swallow anything during the whole week, so after getting permission from the owner, the horse was euthanized on day 10. Samples of the colonic content and blood serum were sent by courier to the laboratory for toxin neutralization, however, botulinum neurotoxins could not be detected. After that, serum samples from days 6 and 10 were sent to another laboratory for testing for botulinum neurotoxin antibodies by ELISA. Specific antibodies against botulinum neurotoxin type A were measured, indicating a previous, immuno-relevant contact with the toxin. This seroconversion for type A supports the clinical botulism diagnosis. Type A botulism is rarely seen in Europe and has been detected in a horse in Turkey for the first time.

scholarly journals Frizzled3 controls axonal development in distinct populations of cranial and spinal motor neurons

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Zhong L Hua ◽  
Philip M Smallwood ◽  
Jeremy Nathans
Keyword(s):  
Cell Death ◽  
Motor Neurons ◽  
Planar Cell Polarity ◽  
Motor Nerve ◽  
Normal Wave ◽  
Axon Growth ◽  
Axonal Growth ◽  
Cell Complexes ◽  
Developing Neurons

Disruption of the Frizzled3 (Fz3) gene leads to defects in axonal growth in the VIIth and XIIth cranial motor nerves, the phrenic nerve, and the dorsal motor nerve in fore- and hindlimbs. In Fz3−/− limbs, dorsal axons stall at a precise location in the nerve plexus, and, in contrast to the phenotypes of several other axon path-finding mutants, Fz3−/− dorsal axons do not reroute to other trajectories. Affected motor neurons undergo cell death 2 days prior to the normal wave of developmental cell death that coincides with innervation of muscle targets, providing in vivo evidence for the idea that developing neurons with long-range axons are programmed to die unless their axons arrive at intermediate targets on schedule. These experiments implicate planar cell polarity (PCP) signaling in motor axon growth and they highlight the question of how PCP proteins, which form cell–cell complexes in epithelia, function in the dynamic context of axonal growth.

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