scholarly journals Neurotoxic peptides from the venom of the giant Australian stinging tree

2020 ◽  
Vol 6 (38) ◽  
pp. eabb8828
Author(s):  
Edward K. Gilding ◽  
Sina Jami ◽  
Jennifer R. Deuis ◽  
Mathilde R. Israel ◽  
Peta J. Harvey ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Sodium Channels ◽  
Sensory Neurons ◽  
Convergent Evolution ◽  
3D Structure ◽  
Cone Snail ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Sensory Effects ◽  
Mammalian Skin

Stinging trees from Australasia produce remarkably persistent and painful stings upon contact of their stiff epidermal hairs, called trichomes, with mammalian skin. Dendrocnide-induced acute pain typically lasts for several hours, and intermittent painful flares can persist for days and weeks. Pharmacological activity has been attributed to small-molecule neurotransmitters and inflammatory mediators, but these compounds alone cannot explain the observed sensory effects. We show here that the venoms of Australian Dendrocnide species contain heretofore unknown pain-inducing peptides that potently activate mouse sensory neurons and delay inactivation of voltage-gated sodium channels. These neurotoxins localize specifically to the stinging hairs and are miniproteins of 4 kDa, whose 3D structure is stabilized in an inhibitory cystine knot motif, a characteristic shared with neurotoxins found in spider and cone snail venoms. Our results provide an intriguing example of inter-kingdom convergent evolution of animal and plant venoms with shared modes of delivery, molecular structure, and pharmacology.

scholarly journals Neuropathic Pain Develops Normally in Mice Lacking both Nav1.7 and Nav1.8

2005 ◽  
Vol 1 ◽  
pp. 1744-8069-1-24 ◽  
Author(s):  
Mohammed A Nassar ◽  
Alessandra Levato ◽  
L Caroline Stirling ◽  
John N Wood
Keyword(s):  
Neuropathic Pain ◽  
Sodium Channels ◽  
Sensory Neurons ◽  
Inflammatory Pain ◽  
Pain Thresholds ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Pain Symptoms ◽  
Α Subunits

Two voltage gated sodium channel α-subunits, Nav1.7 and Nav1.8, are expressed at high levels in nociceptor terminals and have been implicated in the development of inflammatory pain. Mis-expression of voltage-gated sodium channels by damaged sensory neurons has also been implicated in the development of neuropathic pain, but the role of Nav1.7 and Nav1.8 is uncertain. Here we show that deleting Nav1.7 has no effect on the development of neuropathic pain. Double knockouts of both Nav1.7 and Nav1.8 also develop normal levels of neuropathic pain, despite a lack of inflammatory pain symptoms and altered mechanical and thermal acute pain thresholds. These studies demonstrate that, in contrast to the highly significant role for Nav1.7 in determining inflammatory pain thresholds, the development of neuropathic pain does not require the presence of either Nav1.7 or Nav1.8 alone or in combination.

scholarly journals Conserved Expression of Nav1.7 and Nav1.8 Contribute to the Spontaneous and Thermally Evoked Excitability in IL-6 and NGF-Sensitized Adult Dorsal Root Ganglion Neurons In Vitro

2020 ◽  
Vol 7 (2) ◽  
pp. 44
Author(s):  
Rahul R. Atmaramani ◽  
Bryan J. Black ◽  
June Bryan de la Peña ◽  
Zachary T. Campbell ◽  
Joseph J. Pancrazio
Keyword(s):  
Sodium Channels ◽  
Sensory Neurons ◽  
Inflammatory Pain ◽  
Dorsal Root Ganglion Neurons ◽  
Electrode Arrays ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Ganglion Neurons

Sensory neurons respond to noxious stimuli by relaying information from the periphery to the central nervous system via action potentials driven by voltage-gated sodium channels, specifically Nav1.7 and Nav1.8. These channels play a key role in the manifestation of inflammatory pain. The ability to screen compounds that modulate voltage-gated sodium channels using cell-based assays assumes that key channels present in vivo is maintained in vitro. Prior electrophysiological work in vitro utilized acutely dissociated tissues, however, maintaining this preparation for long periods is difficult. A potential alternative involves multi-electrode arrays which permit long-term measurements of neural spike activity and are well suited for assessing persistent sensitization consistent with chronic pain. Here, we demonstrate that the addition of two inflammatory mediators associated with chronic inflammatory pain, nerve growth factor (NGF) and interleukin-6 (IL-6), to adult DRG neurons increases their firing rates on multi-electrode arrays in vitro. Nav1.7 and Nav1.8 proteins are readily detected in cultured neurons and contribute to evoked activity. The blockade of both Nav1.7 and Nav1.8, has a profound impact on thermally evoked firing after treatment with IL-6 and NGF. This work underscores the utility of multi-electrode arrays for pharmacological studies of sensory neurons and may facilitate the discovery and mechanistic analyses of anti-nociceptive compounds.

scholarly journals Voltage-Gated Sodium Channels: A Prominent Target of Marine Toxins

Marine Drugs ◽  
2021 ◽  
Vol 19 (10) ◽  
pp. 562
Author(s):  
Rawan Mackieh ◽  
Rita Abou-Nader ◽  
Rim Wehbe ◽  
César Mattei ◽  
Christian Legros ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Physiological Role ◽  
Supporting Cell ◽  
Cone Snail ◽  
Marine Toxins ◽  
Marine Animals ◽  
Communication Signals ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Wide Range

Voltage-gated sodium channels (VGSCs) are considered to be one of the most important ion channels given their remarkable physiological role. VGSCs constitute a family of large transmembrane proteins that allow transmission, generation, and propagation of action potentials. This occurs by conducting Na+ ions through the membrane, supporting cell excitability and communication signals in various systems. As a result, a wide range of coordination and physiological functions, from locomotion to cognition, can be accomplished. Drugs that target and alter the molecular mechanism of VGSCs’ function have highly contributed to the discovery and perception of the function and the structure of this channel. Among those drugs are various marine toxins produced by harmful microorganisms or venomous animals. These toxins have played a key role in understanding the mode of action of VGSCs and in mapping their various allosteric binding sites. Furthermore, marine toxins appear to be an emerging source of therapeutic tools that can relieve pain or treat VGSC-related human channelopathies. Several studies documented the effect of marine toxins on VGSCs as well as their pharmaceutical applications, but none of them underlined the principal marine toxins and their effect on VGSCs. Therefore, this review aims to highlight the neurotoxins produced by marine animals such as pufferfish, shellfish, sea anemone, and cone snail that are active on VGSCs and discuss their pharmaceutical values.

scholarly journals The Role of Voltage-Gated Sodium Channels in Pain Signaling

2019 ◽  
Vol 99 (2) ◽  
pp. 1079-1151 ◽  
Author(s):  
David L. Bennett ◽  
Alex J. Clark ◽  
Jianying Huang ◽  
Stephen G. Waxman ◽  
Sulayman D. Dib-Hajj
Keyword(s):  
Chronic Pain ◽  
Sodium Channels ◽  
Sensory Neuron ◽  
Sensory Neurons ◽  
Expression Patterns ◽  
Sensory Transduction ◽  
Gene Variants ◽  
Sensory Stimuli ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels

Acute pain signaling has a key protective role and is highly evolutionarily conserved. Chronic pain, however, is maladaptive, occurring as a consequence of injury and disease, and is associated with sensitization of the somatosensory nervous system. Primary sensory neurons are involved in both of these processes, and the recent advances in understanding sensory transduction and human genetics are the focus of this review. Voltage-gated sodium channels (VGSCs) are important determinants of sensory neuron excitability: they are essential for the initial transduction of sensory stimuli, the electrogenesis of the action potential, and neurotransmitter release from sensory neuron terminals. Nav1.1, Nav1.6, Nav1.7, Nav1.8, and Nav1.9 are all expressed by adult sensory neurons. The biophysical characteristics of these channels, as well as their unique expression patterns within subtypes of sensory neurons, define their functional role in pain signaling. Changes in the expression of VGSCs, as well as posttranslational modifications, contribute to the sensitization of sensory neurons in chronic pain states. Furthermore, gene variants in Nav1.7, Nav1.8, and Nav1.9 have now been linked to human Mendelian pain disorders and more recently to common pain disorders such as small-fiber neuropathy. Chronic pain affects one in five of the general population. Given the poor efficacy of current analgesics, the selective expression of particular VGSCs in sensory neurons makes these attractive targets for drug discovery. The increasing availability of gene sequencing, combined with structural modeling and electrophysiological analysis of gene variants, also provides the opportunity to better target existing therapies in a personalized manner.

Sensory renal innervation: a kidney-specific firing activity due to a unique expression pattern of voltage-gated sodium channels?

2013 ◽  
Vol 304 (5) ◽  
pp. F491-F497 ◽  
Author(s):  
Wolfgang Freisinger ◽  
Johannes Schatz ◽  
Tilmann Ditting ◽  
Angelika Lampert ◽  
Sonja Heinlein ◽  
...  
Keyword(s):  
Action Potential ◽  
Sodium Channels ◽  
Sensory Neurons ◽  
Firing Pattern ◽  
Drg Neurons ◽  
Action Potential Firing ◽  
Tonic Firing ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Potential Firing

Sensory neurons with afferent axons from the kidney are extraordinary in their response to electrical stimulation. More than 50% exhibit a tonic firing pattern, i.e., sustained action potential firing throughout depolarizing, pointing to an increased excitability, whereas nonrenal neurons show mainly a phasic response, i.e., less than five action potentials. Here we investigated whether these peculiar firing characteristics of renal afferent neurons are due to differences in the expression of voltage-gated sodium channels (Navs). Dorsal root ganglion (DRG) neurons from rats (Th11-L2) were recorded by the current-clamp technique and distinguished as “tonic” or “phasic.” In voltage-clamp recordings, Navs were characterized by their tetrodotoxoxin (TTX) sensitivity, and their molecular identity was revealed by RT-PCR. The firing pattern of 66 DRG neurons (41 renal and 25 nonrenal) was investigated. Renal neurons exhibited more often a tonic firing pattern (56.1 vs. 12%). Tonic neurons showed a more positive threshold (−21.75 ± 1.43 vs.−29.33 ± 1.63 mV; P < 0.05), a higher overshoot (56.74 [53.6–60.96] vs. 46.79 mV [38.63–54.75]; P < 0.05) and longer action potential duration (4.61 [4.15–5.85] vs. 3.35 ms [2.12–5.67]; P < 0.05). These findings point to an increased presence of the TTX-resistant Navs 1.8 and 1.9. Furthermore, tonic neurons exhibited a relatively higher portion of TTX-resistant sodium currents. Interestingly, mRNA expression of TTX-resistant sodium channels was significantly increased in renal, predominantly tonic, DRG neurons. Hence, under physiological conditions, renal sensory neurons exhibit predominantly a firing pattern associated with higher excitability. Our findings support that this is due to an increased expression and activation of TTX-resistant Navs.

scholarly journals Voltage-gated sodium channels in nociceptiveversusnon-nociceptive nodose vagal sensory neurons innervating guinea pig lungs

2008 ◽  
Vol 586 (5) ◽  
pp. 1321-1336 ◽  
Author(s):  
Kevin Kwong ◽  
Michael J. Carr ◽  
Anna Gibbard ◽  
Tony J. Savage ◽  
Kuljit Singh ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Sodium Channels ◽  
Sensory Neurons ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels

scholarly journals Insights into the origins of fish hunting in venomous cone snails from studies of Conus tessulatus

2015 ◽  
Vol 112 (16) ◽  
pp. 5087-5092 ◽  
Author(s):  
Joseph W. Aman ◽  
Julita S. Imperial ◽  
Beatrix Ueberheide ◽  
Min-Min Zhang ◽  
Manuel Aguilar ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Molecular Mechanisms ◽  
Prey Capture ◽  
Sequence Similarity ◽  
Cone Snail ◽  
Evolutionary Transitions ◽  
Voltage Gated ◽  
Channel Inactivation ◽  
Voltage Gated Sodium Channels ◽  
Cone Snails

Prey shifts in carnivorous predators are events that can initiate the accelerated generation of new biodiversity. However, it is seldom possible to reconstruct how the change in prey preference occurred. Here we describe an evolutionary “smoking gun” that illuminates the transition from worm hunting to fish hunting among marine cone snails, resulting in the adaptive radiation of fish-hunting lineages comprising ∼100 piscivorous Conus species. This smoking gun is δ-conotoxin TsVIA, a peptide from the venom of Conus tessulatus that delays inactivation of vertebrate voltage-gated sodium channels. C. tessulatus is a species in a worm-hunting clade, which is phylogenetically closely related to the fish-hunting cone snail specialists. The discovery of a δ-conotoxin that potently acts on vertebrate sodium channels in the venom of a worm-hunting cone snail suggests that a closely related ancestral toxin enabled the transition from worm hunting to fish hunting, as δ-conotoxins are highly conserved among fish hunters and critical to their mechanism of prey capture; this peptide, δ-conotoxin TsVIA, has striking sequence similarity to these δ-conotoxins from piscivorous cone snail venoms. Calcium-imaging studies on dissociated dorsal root ganglion (DRG) neurons revealed the peptide’s putative molecular target (voltage-gated sodium channels) and mechanism of action (inhibition of channel inactivation). The results were confirmed by electrophysiology. This work demonstrates how elucidating the specific interactions between toxins and receptors from phylogenetically well-defined lineages can uncover molecular mechanisms that underlie significant evolutionary transitions.

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