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https://www.readbyqxmd.com/read/28916793/oligodendroglial-excitability-mediated-by-glutamatergic-inputs-and-nav1-2-activation
#1
Emmanuelle Berret, Tara Barron, Jie Xu, Emily Debner, Eun Jung Kim, Jun Hee Kim
Oligodendrocyte (OL) maturation and axon-glial communication are required for proper myelination in the developing brain. However, physiological properties of OLs remain largely uncharacterized in different brain regions. The roles of oligodendroglial voltage-activated Na(+) channels (Nav) and electrical excitability in relation to maturation to the myelinating stage are controversial, although oligodendroglial excitability is potentially important for promoting axon myelination. Here we show spiking properties of OLs and their role in axon-glial communication in the auditory brainstem...
September 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28905186/antidepressants-inhibit-nav1-3-nav1-7-and-nav1-8-neuronal-voltage-gated-sodium-channels-more-potently-than-nav1-2-and-nav1-6-channels-expressed-in-xenopus-oocytes
#2
Takafumi Horishita, Nobuyuki Yanagihara, Susumu Ueno, Dan Okura, Reiko Horishita, Tomoko Minami, Yuichi Ogata, Yuka Sudo, Yasuhito Uezono, Takeyoshi Sata, Takashi Kawasaki
Tricyclic antidepressants (TCAs) and duloxetine are used to treat neuropathic pain. However, the mechanisms underlying their analgesic effects remain unclear. Although many investigators have shown inhibitory effects of antidepressants on voltage-gated sodium channels (Nav) as a possible mechanism of analgesia, to our knowledge, no one has compared effects on the diverse variety of sodium channel α subunits. We investigated the effects of antidepressants on sodium currents in Xenopus oocytes expressing Nav1...
September 14, 2017: Naunyn-Schmiedeberg's Archives of Pharmacology
https://www.readbyqxmd.com/read/28902151/apetx4-a-novel-sea-anemone-toxin-and-a-modulator-of-the-cancer-relevant-potassium-channel-kv10-1
#3
Lien Moreels, Steve Peigneur, Diogo T Galan, Edwin De Pauw, Lászlo Béress, Etienne Waelkens, Luis A Pardo, Loïc Quinton, Jan Tytgat
The human ether-à-go-go channel (hEag1 or KV10.1) is a cancer-relevant voltage-gated potassium channel that is overexpressed in a majority of human tumors. Peptides that are able to selectively inhibit this channel can be lead compounds in the search for new anticancer drugs. Here, we report the activity-guided purification and electrophysiological characterization of a novel KV10.1 inhibitor from the sea anemone Anthopleura elegantissima. Purified sea anemone fractions were screened for inhibitory activity on KV10...
September 13, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28882890/c-terminal-phosphorylation-of-nav1-5-impairs-fgf13-dependent-regulation-of-channel-inactivation
#4
Sophie Burel, Fabien C Coyan, Maxime Lorenzini, Matthew R Meyer, Cheryl F Lichti, Joan H Brown, Gildas Loussouarn, Flavien Charpentier, Jeanne M Nerbonne, R Reid Townsend, Lars S Maier, Céline Marionneau
Voltage-gated Na(+) (NaV) channels are key regulators of myocardial excitability, and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII)-dependent alterations in NaV1.5 channel inactivation are emerging as a critical determinant of arrhythmias in heart failure. However, the global native phosphorylation pattern of NaV1.5 subunits associated with these arrhythmogenic disorders, and the associated channel regulatory defects remain unknown. Here, we undertook phosphoproteomic analyses to identify and quantify in situ the phosphorylation sites in the NaV1...
September 7, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28880874/discovery-and-mode-of-action-of-a-novel-analgesic-%C3%AE-toxin-from-the-african-spider-ceratogyrus-darlingi
#5
Silmara R Sousa, Joshua S Wingerd, Andreas Brust, Christopher Bladen, Lotten Ragnarsson, Volker Herzig, Jennifer R Deuis, Sebastien Dutertre, Irina Vetter, Gerald W Zamponi, Glenn F King, Paul F Alewood, Richard J Lewis
Spider venoms are rich sources of peptidic ion channel modulators with important therapeutical potential. We screened a panel of 60 spider venoms to find modulators of ion channels involved in pain transmission. We isolated, synthesized and pharmacologically characterized Cd1a, a novel peptide from the venom of the spider Ceratogyrus darlingi. Cd1a reversibly paralysed sheep blowflies (PD50 of 1318 pmol/g) and inhibited human Cav2.2 (IC50 2.6 μM) but not Cav1.3 or Cav3.1 (IC50 > 30 μM) in fluorimetric assays...
2017: PloS One
https://www.readbyqxmd.com/read/28871036/sodium-channel-%C3%AE-2-subunits-prevent-action-potential-propagation-failures-at-axonal-branch-points
#6
In Ha Cho, Lauren C Panzera, Morven Chin, Michael B Hoppa
Neurotransmitter release depends on voltage-gated Na(+) channels (Navs) to successfully propagate an action potential (AP) from the axon hillock to a synaptic terminal. Unmyelinated sections of axon are very diverse structures encompassing branch points and numerous presynaptic terminals with undefined molecular partners of Na(+) channels. Using optical recordings of Ca(2+) and membrane voltage, we demonstrate that Na(+) channel β2 subunits (Navβ2) are required to prevent AP propagation failures across the axonal arborization of cultured rat hippocampal neurons (mixed male and female)...
September 4, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28832970/differential-binding-of-tetrodotoxin-and-its-derivatives-to-voltage-sensitive-sodium-channel-subtypes-nav-1-1-to-nav-1-7
#7
Tadaaki Tsukamoto, Yukie Chiba, Minoru Wakamori, Tomoshi Yamada, Shunsuke Tsunogae, Yuko Cho, Ryo Sakakibara, Takuya Imazu, Shouta Tokoro, Yoshiki Satake, Masaatsu Adachi, Toshio Nishikawa, Mari Yotsu-Yamashita, Keiichi Konoki
BACKGROUND AND PURPOSE: The development of subtype-selective ligands to inhibit voltage-sensitive sodium channels (VSSCs) has been attempted with the aim of developing therapeutic compounds. Tetrodotoxin is a toxin from pufferfish that strongly inhibits VSSCs. Many tetrodotoxin analogues have been identified from marine and terrestrial sources, although their specificity for particular VSSC subtypes has not been investigated. Herein, we describe the binding of 11 tetrodotoxin analogues to human VSSC subtypes Nav 1...
August 18, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28758202/sodium-channel-subtypes-are-differentially-localized-to-pre-and-post-synaptic-sites-in-rat-hippocampus
#8
Kenneth W Johnson, Karl F Herold, Teresa A Milner, Hugh C Hemmings, Jimcy Platholi
Voltage-gated Na(+) channels (Nav ) modulate neuronal excitability, but the roles of the various Nav subtypes in specific neuronal functions such as synaptic transmission are unclear. We investigated expression of the three major brain Nav subtypes (Nav 1.1, Nav 1.2, Nav 1.6) in area CA1 and dentate gyrus of rat hippocampus. Using light and electron microscopy, we found labeling for all three Nav subtypes on dendrites, dendritic spines, and axon terminals, but the proportion of pre- and post-synaptic labeling for each subtype varied within and between subregions of CA1 and dentate gyrus...
July 31, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28749537/sodium-channels-and-pain-from-toxins-to-therapies
#9
REVIEW
Fernanda C Cardoso, Richard J Lewis
Voltage-gated sodium channels (NaV ) are essential to initiation and propagation of action potentials that critically influence our ability to respond to a diverse range of stimuli. Physiological and pharmacological studies have linked abnormal function of Nav channels to many human disorders, including chronic neuropathic pain. These findings, along with the description of the functional properties and expression pattern of NaV channels subtypes, are helping to uncover subtype specific roles in acute and chronic pain, and revealing potential opportunities to target these with selective inhibitors...
July 27, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28735751/structure-of-the-nav1-4-%C3%AE-1-complex-from-electric-eel
#10
Zhen Yan, Qiang Zhou, Lin Wang, Jianping Wu, Yanyu Zhao, Gaoxingyu Huang, Wei Peng, Huaizong Shen, Jianlin Lei, Nieng Yan
Voltage-gated sodium (Nav) channels initiate and propagate action potentials. Here, we present the cryo-EM structure of EeNav1.4, the Nav channel from electric eel, in complex with the β1 subunit at 4.0 Å resolution. The immunoglobulin domain of β1 docks onto the extracellular L5I and L6IV loops of EeNav1.4 via extensive polar interactions, and the single transmembrane helix interacts with the third voltage-sensing domain (VSDIII). The VSDs exhibit "up" conformations, while the intracellular gate of the pore domain is kept open by a digitonin-like molecule...
July 27, 2017: Cell
https://www.readbyqxmd.com/read/28734073/differential-calcium-sensitivity-in-nav-1-5-mixed-syndrome-mutants
#11
Mena Abdelsayed, Alban-Elouen Baruteau, Karen Gibbs, Shubhayan Sanatani, Andrew D Krahn, Vincent Probst, Peter C Ruben
KEY POINTS: SCN5a mutations may express gain-of-function (Long QT Syndrome-3), loss-of-function (Brugada Syndrome 1) or both (mixed syndromes), depending on the mutation and environmental triggers. One such trigger may be an increase in cytosolic calcium, accompanying exercise. Many mixed syndromes mutants, including ∆KPQ, E1784K, 1795insD and Q1909R, are found in calcium-sensitive regions. Elevated cytosolic calcium attenuates gain-of-function properties in ∆KPQ, 1795insD and Q1909R, but not in E1784K...
September 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28734032/characterization-of-the-axon-initial-segment-of-mice-substantia-nigra-dopaminergic-neurons
#12
Cristian González-Cabrera, Rodrigo Meza, Lorena Ulloa, Paulina Merino-Sepúlveda, Valentina Luco, Ana Sanhueza, Alejandro Oñate-Ponce, J Paul Bolam, Pablo Henny
The axon initial segment (AIS) is the site of initiation of action potentials and influences action potential waveform, firing pattern, and rate. In view of the fundamental aspects of motor function and behavior that depend on the firing of substantia nigra pars compacta (SNc) dopaminergic neurons, we identified and characterized their AIS in the mouse. Immunostaining for tyrosine hydroxylase (TH), sodium channels (Nav ) and ankyrin-G (Ank-G) was used to visualize the AIS of dopaminergic neurons. Reconstructions of sampled AIS of dopaminergic neurons revealed variable lengths (12-60 μm) and diameters (0...
July 22, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28726749/ladder-shaped-ion-channel-ligands-current-state-of-knowledge
#13
REVIEW
Yuri B Shmukler, Denis A Nikishin
Ciguatoxins (CTX) and brevetoxins (BTX) are polycyclic ethereal compounds biosynthesized by the worldwide distributed planktonic and epibenthic dinoflagellates of Gambierdiscus and Karenia genera, correspondingly. Ciguatera, evoked by CTXs, is a type of ichthyosarcotoxism, which involves a variety of gastrointestinal and neurological symptoms, while BTXs cause so-called neurotoxic shellfish poisoning. Both types of toxins are reviewed together because of similar mechanisms of their action. These are the only molecules known to activate voltage-sensitive Na⁺-channels in mammals through a specific interaction with site 5 of its α-subunit and may compete for it, which results in an increase in neuronal excitability, neurotransmitter release and impairment of synaptic vesicle recycling...
July 20, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28720591/using-fluorescence-to-understand-%C3%AE-subunit-nav-channel-interactions
#14
Rene Barro-Soria, Sara I Liin, H Peter Larsson
No abstract text is available yet for this article.
July 18, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28720590/mechanisms-of-noncovalent-%C3%AE-subunit-regulation-of-nav-channel-gating
#15
Wandi Zhu, Taylor L Voelker, Zoltan Varga, Angela R Schubert, Jeanne M Nerbonne, Jonathan R Silva
Voltage-gated Na(+) (NaV) channels comprise a macromolecular complex whose components tailor channel function. Key components are the non-covalently bound β1 and β3 subunits that regulate channel gating, expression, and pharmacology. Here, we probe the molecular basis of this regulation by applying voltage clamp fluorometry to measure how the β subunits affect the conformational dynamics of the cardiac NaV channel (NaV1.5) voltage-sensing domains (VSDs). The pore-forming NaV1.5 α subunit contains four domains (DI-DIV), each with a VSD...
July 18, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28712915/comparative-analyses-and-implications-for-antivenom-serotherapy-of-four-moroccan-scorpion-buthus-occitanus-venoms-subspecies-tunetanus-paris-malhommei-and-mardochei
#16
Bruna Luiza Emerich, Maria Elena De Lima, Marie-France Martin-Eauclaire, Pierre E Bougis
Temporary passive immunity such as serotherapy against venoms requires the full knowledge of all venom's components. Here, four venoms from Moroccan common yellow scorpions belonging to Buthus occitanus, subspecies tunetanus, paris, malhommei, and mardochei, all collected in four different restricted areas, were analysed in deep. They were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) and their molecular masse profile determined by off-line MALDI-TOF mass spectrometry. Characterisation of their main components was achieved by enzyme-linked immunosorbent assay (ELISA) using specific antisera against the major lethal scorpion toxins identified so far, i...
July 13, 2017: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28658526/reverse-pharmacogenomics-carbamazepine-normalizes-activation-and-attenuates-thermal-induced-hyperexcitability-of-sensory-neurons-due-to-nav1-7-mutation-i234t
#17
Yang Yang, Talia Adi, Philip Effraim, Lubin Chen, Sulayman D Dib-Hajj, Stephen G Waxman
BACKGROUND AND PURPOSE: Pharmacotherapy for pain currently involves trial-and-error. A previous study on inherited erythromelalgia (a genetic model of neuropathic pain due to mutations in voltage-gated sodium channel Nav1.7) used genomics, structural modeling, biophysical and pharmacological analyses to guide pharmacotherapy, and showed that carbamazepine normalizes voltage-dependence of activation of the Nav1.7-S241T mutant channel, reducing pain in patients carrying this mutation. However, whether this approach is applicable to other Nav mutations is still unknown...
June 28, 2017: British Journal of Pharmacology
https://www.readbyqxmd.com/read/28635024/a-small-molecule-activator-of-nav-1-1-channels-increases-fast-spiking-interneuron-excitability-and-gabaergic-transmission-in%C3%A2-vitro-and-has-anti-convulsive-effects-in%C3%A2-vivo
#18
Kristen Frederiksen, Dunguo Lu, Jinhui Yang, Henrik Sindal Jensen, Jesper Frank Bastlund, Peter Hjørringgaard Larsen, Henry Liu, François Crestey, Kim Dekermendjian, Lassina Badolo, Morten Laursen, Charlotte Hougaard, Charles Yang, Niels Svenstrup, Morten Grunnet
Nav 1.1 (SCN1A) channels primarily located in gamma-aminobutyric acid (GABA)ergic fast-spiking interneurons are pivotal for action potential generation and propagation in these neurons. Inappropriate function of fast-spiking interneurons, leading to disinhibition of pyramidal cells and network desynchronization, correlates with decreased cognitive capability. Further, reduced functionality of Nav 1.1 channels is linked to various diseases in the central nervous system. There is, at present, however no subtype selective pharmacological activators of Nav 1...
August 2017: European Journal of Neuroscience
https://www.readbyqxmd.com/read/28620187/discovery-and-identification-of-o-o-diethyl-o-4-5-phenyl-4-5-dihydroisoxazol-3-yl-phenyl-phosphorothioate-xp-1408-as-a-novel-mode-of-action-of-organophosphorus-insecticides
#19
Zhigang Zeng, Ying Yan, Bingfeng Wang, Niu Liu, Hanhong Xu
Organophosphorus (OP) insecticides play an important role in pest control. Many OP insecticides have been removed from the market because of their high toxicity to humans. We designed and synthesized a new OP insecticide with the goal of providing a low cost, and less toxic insecticide. The mode of action of O, O-diethyl O-(4-(5-phenyl-4, 5-dihydroisoxazol-3-yl) phenyl) phosphorothioate (XP-1408) was studied in Drosophila melanogaster. Bioassays showed that XP-1408 at a concentration of 50 mg/L delayed larval development...
June 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28607094/pharmacology-of-the-nav1-1-domain-iv-voltage-sensor-reveals-coupling-between-inactivation-gating-processes
#20
Jeremiah D Osteen, Kevin Sampson, Vivek Iyer, David Julius, Frank Bosmans
The Nav1.1 voltage-gated sodium channel is a critical contributor to excitability in the brain, where pathological loss of function leads to such disorders as epilepsy, Alzheimer's disease, and autism. This voltage-gated sodium (Nav) channel subtype also plays an important role in mechanical pain signaling by primary afferent somatosensory neurons. Therefore, pharmacologic modulation of Nav1.1 represents a potential strategy for treating excitability disorders of the brain and periphery. Inactivation is a complex aspect of Nav channel gating and consists of fast and slow components, each of which may involve a contribution from one or more voltage-sensing domains...
June 27, 2017: Proceedings of the National Academy of Sciences of the United States of America
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