scholarly journals Discovery, Pharmacological Characterisation and NMR Structure of the Novel µ-Conotoxin SxIIIC, a Potent and Irreversible NaV Channel Inhibitor

Biomedicines ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 391 ◽  
Author(s):  
Kirsten L. McMahon ◽  
Hue N.T. Tran ◽  
Jennifer R. Deuis ◽  
Richard J. Lewis ◽  
Irina Vetter ◽  
...  
Keyword(s):  
Chronic Pain ◽  
Solution Structure ◽  
Neurological Diseases ◽  
The Novel ◽  
Cone Snail ◽  
Whole Cell Patch Clamp ◽  
Channel Selectivity ◽  
Patch Clamp Electrophysiology ◽  
Α Helix ◽  
Drug Leads

Voltage-gated sodium (NaV) channel subtypes, including NaV1.7, are promising targets for the treatment of neurological diseases, such as chronic pain. Cone snail-derived µ-conotoxins are small, potent NaV channel inhibitors which represent potential drug leads. Of the 22 µ-conotoxins characterised so far, only a small number, including KIIIA and CnIIIC, have shown inhibition against human NaV1.7. We have recently identified a novel µ-conotoxin, SxIIIC, from Conus striolatus. Here we present the isolation of native peptide, chemical synthesis, characterisation of human NaV channel activity by whole-cell patch-clamp electrophysiology and analysis of the NMR solution structure. SxIIIC displays a unique NaV channel selectivity profile (1.4 > 1.3 > 1.1 ≈ 1.6 ≈ 1.7 > 1.2 >> 1.5 ≈ 1.8) when compared to other µ-conotoxins and represents one of the most potent human NaV1.7 putative pore blockers (IC50 152.2 ± 21.8 nM) to date. NMR analysis reveals the structure of SxIIIC includes the characteristic α-helix seen in other µ-conotoxins. Future investigations into structure-activity relationships of SxIIIC are expected to provide insights into residues important for NaV channel pore blocker selectivity and subsequently important for chronic pain drug development.

scholarly journals Effect of Geraniol and Citronellol Essential Oils on the Biophysical Gating Properties of AMPA Receptors

2019 ◽  
Vol 9 (21) ◽  
pp. 4693 ◽  
Author(s):  
Mohammad Qneibi ◽  
Nidal Jaradat ◽  
Nour Emwas
Keyword(s):  
Essential Oils ◽  
Ampa Receptors ◽  
Neurological Diseases ◽  
Whole Cell Patch Clamp ◽  
293 Cells ◽  
Future Drug ◽  
Drug Synthesis ◽  
Patch Clamp Electrophysiology ◽  
Calming Effect ◽  
Natural Template

Essential oils have been advertised endlessly to be very beneficial for the health of humans, and an extensive amount of research examines the validity of such claims. In contribution, the current study evaluates the neuroprotective properties of Citronellol and Geraniol essential oils (EOs). In relationship to the biophysical gating properties of different the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunits, the EOs were administered to HEK293 (Human embryonic kidney 293) cells and examined for any inhibition and effect on desensitization or deactivation rates, using whole-cell patch-clamp electrophysiology. Our results demonstrated the highest levels of inhibition from Citronellol oil by four-fold on all AMPARs subunits. Likewise, Geraniol oil had a similar inhibiting impact on the receptors, and both oils decreased the desensitization and deactivation rates of the inhibited receptors. Thus, the examined EOs of this study portray neuroprotective qualities by targeting AMPARs activation and reducing desensitization and deactivation rates. Finally, the results of the current study entail a better understanding of AMPARs, provides a natural template for future drug synthesis to treat neurological diseases associated with excessive AMPAR activation, and offers a possible mechanism by which these essential oils deploy their ‘calming’ effect.

scholarly journals Chemical Synthesis and NMR Solution Structure of Conotoxin GXIA from Conus geographus

Marine Drugs ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 60
Author(s):  
David A. Armstrong ◽  
Ai-Hua Jin ◽  
Nayara Braga Emidio ◽  
Richard J. Lewis ◽  
Paul F. Alewood ◽  
...  
Keyword(s):  
Solution Structure ◽  
3D Structure ◽  
Voltage Sensor ◽  
Solution Nmr ◽  
Striking Similarity ◽  
Amino Acid Peptide ◽  
Wide Range ◽  
Cone Snails ◽  
Drug Leads ◽  
Β Sheet

Conotoxins are disulfide-rich peptides found in the venom of cone snails. Due to their exquisite potency and high selectivity for a wide range of voltage and ligand gated ion channels they are attractive drug leads in neuropharmacology. Recently, cone snails were found to have the capability to rapidly switch between venom types with different proteome profiles in response to predatory or defensive stimuli. A novel conotoxin, GXIA (original name G117), belonging to the I3-subfamily was identified as the major component of the predatory venom of piscivorous Conus geographus. Using 2D solution NMR spectroscopy techniques, we resolved the 3D structure for GXIA, the first structure reported for the I3-subfamily and framework XI family. The 32 amino acid peptide is comprised of eight cysteine residues with the resultant disulfide connectivity forming an ICK+1 motif. With a triple stranded β-sheet, the GXIA backbone shows striking similarity to several tarantula toxins targeting the voltage sensor of voltage gated potassium and sodium channels. Supported by an amphipathic surface, the structural evidence suggests that GXIA is able to embed in the membrane and bind to the voltage sensor domain of a putative ion channel target.

scholarly journals The acquisition and generalization of fear of touch

2020 ◽  
Vol 20 (4) ◽  
pp. 809-819 ◽  
Author(s):  
Emma E. Biggs ◽  
Ann Meulders ◽  
Amanda L. Kaas ◽  
Rainer Goebel ◽  
Johan W. S. Vlaeyen
Keyword(s):  
Chronic Pain ◽  
Stimulus Generalization ◽  
Spontaneous Pain ◽  
The Novel ◽  
Vibrotactile Stimulation ◽  
Differential Acquisition ◽  
New Locations ◽  
Conditioned Responses ◽  
Primary Focus ◽  
Post Hoc

AbstractObjectivesContemporary fear-avoidance models of chronic pain posit that fear of pain, and overgeneralization of fear to non-threatening stimuli is a potential pathway to chronic pain. While increasing experimental evidence supports this hypothesis, a comprehensive investigation requires testing in multiple modalities due to the diversity of symptomatology among individuals with chronic pain. In the present study we used an established tactile fear conditioning paradigm as an experimental model of allodynia and spontaneous pain fluctuations, to investigate whether stimulus generalization occurs resulting in fear of touch spreading to new locations.MethodsIn our paradigm, innocuous touch is presented either paired (predictable context) or unpaired (unpredictable context) with a painful electrocutaneous stimulus (pain-US). In the predictable context, vibrotactile stimulation to the index or little finger was paired with the pain-US (CS+), whilst stimulation of the other finger was never paired with pain (CS−). In the unpredictable context, vibrotactile stimulation to the index and little fingers of the opposite hand (CS1 and CS2) was unpaired with pain, but pain-USs occurred unpredictable during the intertrial interval. During the subsequent generalization phase, we tested the spreading of conditioned responses (self-reported fear of touch and pain expectancy) to the (middle and ring) fingers between the CS+ and CS−, and between the CS1 and CS2.ResultsDifferential fear acquisition was evident in the predictable context from increased self-reported pain expectancy and self-reported fear for the CS + compared to the CS−. However, expectancy and fear ratings to the novel generalization stimuli (GS+ and GS−) were comparable to the responses elicited by the CS−. Participants reported equal levels of pain expectancy and fear to the CS1 and CS2 in the unpredictable context. However, the acquired fear did not spread in this context either: participants reported less pain expectancy and fear to the GS1 and GS2 than to the CS1 and CS2. As in our previous study, we did not observe differential acquisition in the startle responses.ConclusionsWhilst our findings for the acquisition of fear of touch replicate the results from our previous study (Biggs et al., 2017), there was no evidence of fear generalization. We discuss the limitations of the present study, with a primary focus on procedural issues that were further investigated with post-hoc analyses, concluding that the present results do not show support for the hypothesis that stimulus generalization underlies spreading of fear of touch to new locations, and discuss how this may be the consequence of a context change that prevented transfer of acquisition.

scholarly journals Authenticity as a Resilience Factor Against CV-19 Threat Among Those With Chronic Pain and Posttraumatic Stress Disorder

2021 ◽  
Vol 12 ◽  
Author(s):  
David E. Reed ◽  
Elizabeth Lehinger ◽  
Briana Cobos ◽  
Kenneth E. Vail ◽  
Paul S. Nabity ◽  
...  
Keyword(s):  
Posttraumatic Stress Disorder ◽  
Chronic Pain ◽  
Posttraumatic Stress ◽  
Stress Disorder ◽  
Brief Pain Inventory ◽  
The Novel ◽  
Ptsd Symptoms ◽  
Physical Conditions ◽  
Resilience Factors ◽  
Novel Coronavirus

ObjectiveThe novel coronavirus (2019; CV-19) is linked to increases in emotional distress and may be particularly problematic for those with pre-existing mental and physical conditions, such as chronic pain and posttraumatic stress disorder (PTSD). However, little empirical research has been published on resilience factors in these individuals. The present study aims to examine authenticity as a resilience factor among those with chronic pain and/or PTSD.MethodsPrior to the national response to the pandemic (January 10-24, 2020), participants were screened for pain-related disability (Oswestry Disability Index; ODI) and PTSD symptoms (Posttraumatic Checklist for DSM-5; PCL-5), and on the basis of those responses were categorized into one of four groups: healthy, chronic pain only, PTSD only, or comorbid chronic pain and PTSD. During the CV-19 pandemic (May 5-May 13, 2020), participants responded again to the ODI and PCL-5, in addition to the Wood Authenticity Scale, Brief Pain Inventory, and items related to the CV-19 pandemic.ResultsA total of 110 participants (54.55% women), aged 42.19 (SD = 13.16), completed the survey during the pandemic. The comorbid group endorsed higher levels of CV-19 Threat and Impact compared to all other groups. Authenticity moderated this relationship relevant to CV-19 Threat among those in the chronic pain only group, and not in any other group.ConclusionThe comorbid group endorsed higher levels of CV-19 Threat and Impact compared to all other groups. Importantly, greater authenticity was associated with less CV-19 Threat in the chronic pain only group, and not in any other group. The present study also highlights the importance of engaging authentically for those with chronic pain during the pandemic.

scholarly journals Repurposing of Drugs Targeted Against COVID-19 Spike Receptor for Treatment: An In silico Approach

2021 ◽  
Vol 11 (5) ◽  
pp. 13740-13753
Keyword(s):  
Rna Viruses ◽  
Neurological Diseases ◽  
Data Bank ◽  
Spike Protein ◽  
The Novel ◽  
Converting Enzyme ◽  
Enzyme Protein ◽  
Receptor Structure ◽  
Ligand Structure ◽  
Biological Field

An escalating pandemic by the novel SARS-CoV2 is spreading across the globe at a rate. An urgent need for therapy is needed. Initially, the virus appeared first in Wuhan, China, and later approximately in 187 countries worldwide. Coronaviruses are causative of respiratory as well as neurological diseases in humans. The novel zoonotic disease-causing coronaviruses are single-stranded RNA viruses. The coronavirus's outer structure consists of spike protein made up of glycoproteins, which binds to ACE (Angiotensin Converting Enzyme) protein when infected in humans. In the current study, 37 compounds that are already used in the biological field as anti-viral compounds are observed with bioinformatics tools. The repurposing drugs are docked against the spike receptor by molecular Docking. The ligand structure and the receptor structure are retrieved from Protein Data Bank. Patch dock server is an open freeware available for docking procedures. The results include acceleration and score of matched properties showing the feasibility of working the drug against SARS-nCoV. For the visualization of the final docked product, PyMOL and RasWin software’s are used. The scores of each ligand docked against the receptor show the compatibility working against the COVID-19 disease.

scholarly journals Solution Structure of the Carbon Storage Regulator Protein CsrA from Escherichia coli

2005 ◽  
Vol 187 (10) ◽  
pp. 3496-3501 ◽  
Author(s):  
Pablo Gutiérrez ◽  
Yan Li ◽  
Michael J. Osborne ◽  
Ekaterina Pomerantseva ◽  
Qian Liu ◽  
...  
Keyword(s):  
Carbon Storage ◽  
Solution Structure ◽  
Rna Binding ◽  
Binding Motif ◽  
Binding Properties ◽  
Nmr Titration ◽  
C Terminus ◽  
Regulator Protein ◽  
Carbon Storage Regulator ◽  
Α Helix

ABSTRACT The carbon storage regulator A (CsrA) is a protein responsible for the repression of a variety of stationary-phase genes in bacteria. In this work, we describe the nuclear magnetic resonance (NMR)-based structure of the CsrA dimer and its RNA-binding properties. CsrA is a dimer of two identical subunits, each composed of five strands, a small α-helix and a flexible C terminus. NMR titration experiments suggest that the β1-β2 and β3-β4 loops and the C-terminal helix are important elements in RNA binding. Even though the β3-β4 loop contains a highly conserved RNA-binding motif, GxxG, typical of KH domains, our structure excludes CsrA from being a member of this protein family, as previously suggested. A mechanism for the recognition of mRNAs downregulated by CsrA is proposed.

The novel and potent anti-depressive action of triptolide and its influences on hippocampal neuroinflammation in a rat model of depression comorbidity of chronic pain

2017 ◽  
Vol 64 ◽  
pp. 180-194 ◽  
Author(s):  
Xiaofan Hu ◽  
Yulin Dong ◽  
Xiaohang Jin ◽  
Chunkui Zhang ◽  
Ting Zhang ◽  
...  
Keyword(s):  
Chronic Pain ◽  
Rat Model ◽  
The Novel

scholarly journals Solution structure of the strawberry allergen Fra a 1

2012 ◽  
Vol 32 (6) ◽  
pp. 567-575 ◽  
Author(s):  
Christian Seutter von Loetzen ◽  
Kristian Schweimer ◽  
Wilfried Schwab ◽  
Paul Rösch ◽  
Olivia Hartl-Spiegelhauer
Keyword(s):  
Solution Structure ◽  
Three Dimensional ◽  
Protein Family ◽  
Dimensional Structure ◽  
Hydrophobic Pocket ◽  
Pigment Synthesis ◽  
Family Protein ◽  
Pr10 Protein ◽  
Α Helix

The PR10 family protein Fra a 1E from strawberry (Fragaria x ananassa) is down-regulated in white strawberry mutants, and transient RNAi (RNA interference)-mediated silencing experiments confirmed that Fra a 1 is involved in fruit pigment synthesis. In the present study, we determined the solution structure of Fra a 1E. The protein fold is identical with that of other members of the PR10 protein family and consists of a seven-stranded antiparallel β-sheet, two short V-shaped α-helices and a long C-terminal α-helix that encompass a hydrophobic pocket. Whereas Fra a 1E contains the glycine-rich loop that is highly conserved throughout the protein family, the volume of the hydrophobic pocket and the size of its entrance are much larger than expected. The three-dimensional structure may shed some light on its physiological function and may help to further understand the role of PR10 proteins in plants.

scholarly journals Current injection and receptor-mediated excitation produce similar maximal firing rates in hypoglossal motoneurons

2016 ◽  
Vol 115 (3) ◽  
pp. 1307-1313 ◽  
Author(s):  
Hilary E. Wakefield ◽  
Ralph F. Fregosi ◽  
Andrew J. Fuglevand
Keyword(s):  
Time Course ◽  
Input Resistance ◽  
Current Injection ◽  
Synaptic Activity ◽  
High Concentration ◽  
Membrane Potential Change ◽  
Firing Rates ◽  
Whole Cell Patch Clamp ◽  
Patch Clamp Electrophysiology ◽  
High Firing

The maximum firing rates of motoneurons (MNs), activated in response to synaptic drive, appear to be much lower than that elicited by current injection. It could be that the decrease in input resistance associated with increased synaptic activity (but not current injection) might blunt overall changes in membrane depolarization and thereby limit spike-frequency output. To test this idea, we recorded, in the same cells, maximal firing responses to current injection and to synaptic activation. We prepared 300 μm medullary slices in neonatal rats that contained hypoglossal MNs and used whole-cell patch-clamp electrophysiology to record their maximum firing rates in response to triangular-ramp current injections and to glutamate receptor-mediated excitation. Brief pressure pulses of high-concentration glutamate led to significant depolarization, high firing rates, and temporary cessation of spiking due to spike inactivation. In the same cells, we applied current clamp protocols that approximated the time course of membrane potential change associated with glutamate application and with peak current levels large enough to cause spike inactivation. Means (SD) of maximum firing rates obtained in response to glutamate application were nearly identical to those obtained in response to ramp current injection [glutamate 47.1 ± 12.0 impulses (imp)/s, current injection 47.5 ± 11.2 imp/s], even though input resistance was 40% less during glutamate application compared with current injection. Therefore, these data suggest that the reduction in input resistance associated with receptor-mediated excitation does not, by itself, limit the maximal firing rate responses in MNs.

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