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Structural modelling and mutant cycle analysis predict pharmacoresponsiveness of a Nav1.7 mutant channel
Mutations of the NaV1.7 voltage-gated sodium channel are implicated in abnormal pain signal transduction. Yang and colleagues perform structural modeling, mutant cycle analysis and electrophysiology on specific mutants and find that they can accurately predict their response profiles to channel blockers.
- Yang Yang
- , Sulayman D. Dib-Hajj
- & Stephen G. Waxman
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CaV1.3-selective L-type calcium channel antagonists as potential new therapeutics for Parkinson's disease
L-type calcium channels comprising the CaV1.3 subunit have been linked to the generation of mitochondrial oxidant stress in Parkinson’s disease. Kang et al. identify pyrimidine-2,4,6-triones as a potential molecular scaffold, which they modify to develop a potent and highly selective CaV1.3 antagonist.
- Soosung Kang
- , Garry Cooper
- & Richard B. Silverman
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| Open AccessStructure of a bacterial voltage-gated sodium channel pore reveals mechanisms of opening and closing
Sodium-gated ion channels open and close in response to the flow of ions. Here, McCusker et al.report the open structure of a sodium-gated ion channel pore from a bacterial homologue, and show, by comparison with the closed structure, that the movement of a C-terminal helix is sufficient to open the channel.
- Emily C. McCusker
- , Claire Bagnéris
- & B.A. Wallace
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Robust photoregulation of GABAA receptors by allosteric modulation with a propofol analogue
The design of chemical photoswitches could potentially lead to the development of novel therapeutics that regulates neurotransmission. In this study, a light-sensitive modified derivative of propofol is shown to activate GABAA receptors in Xenopusoocytes, rat ganglion cells and mouse cerebellar slices.
- Lan Yue
- , Michal Pawlowski
- & David R. Pepperberg
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Identification of the functional binding pocket for compounds targeting small-conductance Ca2+-activated potassium channels
Small- and intermediate-conductance K+channels are activated by calcium-bound calmodulin and modulated by small molecules. In this study, a functional binding pocket for the 1-EBIO class of modulators is described and is located at the calmodulin-channel interface.
- Miao Zhang
- , John M. Pascal
- & Ji-Fang Zhang
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Organellar mechanosensitive channels in fission yeast regulate the hypo-osmotic shock response
Mechanosensitive channels are required to sense cell swelling in response to osmotic shock. Nakayamaet al.report that Msy1 and Msy2 are the fission yeast homologues of the bacterial mechanosensitive channel MscS, and are required for regulating intracellular calcium in response to cell swelling.
- Yoshitaka Nakayama
- , Kenjiro Yoshimura
- & Hidetoshi Iida
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Controlled delivery of bioactive molecules into live cells using the bacterial mechanosensitive channel MscL
The bacterial channel protein MscL opens in response to mechanical forces and could be exploited for vesicular-based drug delivery. Doerneret al. show that functional MscL can be expressed in mammalian cells and facilitate the controlled cellular uptake of relatively large, membrane-impermeable bioactive molecules.
- Julia F. Doerner
- , Sebastien Febvay
- & David E. Clapham
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Gating of cyclic nucleotide-gated channels is voltage dependent
Cyclic nucleotide-gated channels are apparently voltage insensitive despite having the S4-type voltage sensor. Marchesiet al.show that the gating of wild-type CNGA1 and native CNG channels is voltage-independent in the presence of Li+, Na+ and K+, but that it is voltage-dependent in the presence of Rb+, Cs+ and organic cations.
- Arin Marchesi
- , Monica Mazzolini
- & Vincent Torre
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| Open AccessStructure of the Acid-sensing ion channel 1 in complex with the gating modifier Psalmotoxin 1
The activity of the Acid sensing ion channel 1, ASIC1, can be modulated by the gating modifier Psalmotoxin 1 but the molecular mechanism is unclear. Dawsonet al. report the structure of chicken ASIC1 bound to Psalmotoxin 1 and find that the toxin locks two regulatory regions of the channel into a desensitized conformation.
- Roger J.P. Dawson
- , Jörg Benz
- & Armin Ruf
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| Open AccessThe cytoplasmic coiled-coil mediates cooperative gating temperature sensitivity in the voltage-gated H+ channel Hv1
In the dimeric voltage-gated H+channel, Hv1/VSOP, the gating of each subunit is coupled, but the molecular basis of dimer formation and intersubunit coupling is unclear. This study shows that channel assembly and cooperative gating are mediated by the cytoplasmic domain.
- Yuichiro Fujiwara
- , Tatsuki Kurokawa
- & Yasushi Okamura
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| Open AccessDistinct Nav1.7-dependent pain sensations require different sets of sensory and sympathetic neurons
Sodium channel Nav1.7 is essential for acute human pain but its role in chronic neuropathic pain is unclear. Minett and colleagues show that Nav1.7 expression specifically in sympathetic neurons, rather than sensory neurons, is required for the development of chronic neuropathic pain after injury.
- Michael S. Minett
- , Mohammed A. Nassar
- & John N. Wood
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| Open AccessThe C-terminal helical bundle of the tetrameric prokaryotic sodium channel accelerates the inactivation rate
Many channels have cytosolic domains which regulate channel function. Irieet al. show that the cytosolic C-terminal region of NavSulP, a prokaryotic voltage-gated sodium channel, forms a four-helix bundle which stabilises the tetrameric channel and accelerates channel inactivation.
- Katsumasa Irie
- , Takushi Shimomura
- & Yoshinori Fujiyoshi
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Nanodomain Ca2+ of Ca2+ channels detected by a tethered genetically encoded Ca2+ sensor
Calcium nanodomains arise from the cytoplasmic mouth of calcium channels but have not been directly visualized. In this study, the nanodomain of the CaV2.2 calcium channel is imaged using total internal reflection fluorescence microscopy and a genetically encoded calcium sensor attached to the carboxy terminus.
- Lai Hock Tay
- , Ivy E. Dick
- & David T. Yue
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Transient activation of specific neurons in mice by selective expression of the capsaicin receptor
The ability to spatially and temporally control excitation of neuronsin vivo is an invaluable tool. By expressing the TRPV1 receptor in specific neuronal populations, Güler et al. have developed a rapid and noninvasive method to stimulate neuronal activity by the simple administration of capsaicin.
- Ali D. Güler
- , Aundrea Rainwater
- & Richard D. Palmiter
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Lipid storage disorders block lysosomal trafficking by inhibiting a TRP channel and lysosomal calcium release
Accumulation of lysosomal lipids is a feature of Niemann'-Picks (NP) disease, but how these lipids contribute to the disease is unclear. In this study, calcium released via the lysosomal TRPML1 channel is shown to be reduced in NP-type C cells, and sphingomyelins are found to inhibit the channel's activity.
- Dongbiao Shen
- , Xiang Wang
- & Haoxing Xu
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| Open AccessStructure of the pentameric ligand-gated ion channel ELIC cocrystallized with its competitive antagonist acetylcholine
The pentameric ligand gated ion channel fromErwinia chrysanthemi(ELIC) is similar in structure to the nicotinic acetylcholine receptor, a member of the Cys-loop receptor family. This study reports the crystal structure of ELIC bound to acetylcholine and shows that acetylcholine is a competitive antagonist of ELIC.
- Jianjun Pan
- , Qiang Chen
- & Pei Tang
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Perturbation of sodium channel structure by an inherited Long QT Syndrome mutation
Perturbation of the cardiac voltage-gated sodium channel, NaV1.5, by drugs or inherited mutation can underlie and trigger cardiac arrhythmias. Here, the role of the NaV1.5 carboxy terminus in channel inactivation is investigated, and structural details of an arrhythmia associated H6 mutant are reported.
- Ian W. Glaaser
- , Jeremiah D. Osteen
- & Robert S. Kass
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| Open AccessActivation of TRPC6 channels is essential for lung ischaemia–reperfusion induced oedema in mice
The signalling cascade involved in lung ischaemia–reperfusion-induced oedema is poorly understood. Using knockout mice, Weissmannet al. propose a model in which reactive oxygen species production by endothelial NOX2 leads to phospholipase C-γ activation, DAG kinase inhibition and subsequent TRPC6 activation.
- Norbert Weissmann
- , Akylbek Sydykov
- & Alexander Dietrich
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Structural rearrangements underlying ligand-gating in Kir channels
Inward rectifier potassium channels are regulated by a range of ligands that act on a common gate, but the structural details of gating are unclear. Here, the molecular motions associated with gating of KirBac1.1 channels are assessed using small molecule fluorescent probes attached to introduced cysteines.
- Shizhen Wang
- , Sun-Joo Lee
- & Colin G. Nichols
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Modulation of rod photoreceptor output by HCN1 channels is essential for regular mesopic cone vision
At light levels where both rods and cones are active, their signals converge into shared downstream retinal circuitry. Using HCN1 deficient mice, this study shows that the signals from cone photoreceptors are overwhelmed when rod output is not regulated, suggesting a mechanism for how these systems interact.
- Mathias W. Seeliger
- , Arne Brombas
- & Frank Müller
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NMDA receptor activation requires remodelling of intersubunit contacts within ligand-binding heterodimers
In non-NMDA glutamate receptors, intersubunit contacts within agonist binding domains affect functional desensitization. Now, NMDA receptor activation, but not desensitization, is shown to involve rearrangements at the heterodimer interface, suggesting that the intersubunit contacts of NMDA and non-NMDA receptors may have distinct functional roles.
- William F. Borschel
- , Swetha E. Murthy
- & Gabriela K. Popescu
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| Open AccessMolecular mechanism for 3:1 subunit stoichiometry of rod cyclic nucleotide-gated ion channels
The assembly mechanisms of heteromeric ion channels are poorly understood. Using a range of techniques, Shuartet al.determine the mechanism by which rod photoreceptor cyclic nucleotide-gated channels assume a 3:1 stoichiometry of CNGA1 and CNGB1 subunits.
- Noah G. Shuart
- , Yoni Haitin
- & William N. Zagotta
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| Open AccessEditing of human KV1.1 channel mRNAs disrupts binding of the N-terminus tip at the intracellular cavity
RNA editing is important in regulating neuronal excitability, and a specific editing event has been shown to alter the permeation pathway of voltage-gate potassium channels. Gonzalezet al.find that the tip of the channel's inactivation gate makes a direct hydrophobic interaction with the edited position.
- Carlos Gonzalez
- , Angelica Lopez-Rodriguez
- & Miguel Holmgren
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Outlines of the pore in open and closed conformations describe the gating mechanism of ASIC1
The pore gating mechanism of the proton-activated sodium channel ASIC1 is poorly understood. Canessaet al.study the shape of the ion pathway in the ASIC1 channel in its open and closed states, and reveal the opening, closing and desensitization mechanisms of the channel.
- Tianbo Li
- , Youshan Yang
- & Cecilia M. Canessa
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TRPV3 regulates nitric oxide synthase-independent nitric oxide synthesis in the skin
Nitric oxide can be produced by nitric oxide synthase or by nitrite reduction, but whether the latter occurs inside cells is unknown. Here, the TRPV3 ion channel is shown to induce nitrite-dependent nitric oxide production in keratinocytes, where it has a role in thermosensory behaviour and wound healing.
- Takashi Miyamoto
- , Matt J. Petrus
- & Ardem Patapoutian
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| Open AccessRequirement of calcium-activated chloride channels in the activation of mouse vomeronasal neurons
The vomeronasal organ detects pheromones, which are thought to activate TRPC2 channels on the surface of vomeronasal neurons. Using TRPC2 knockout mice, the authors show that urinary pheromones can also activate these neurons via calcium-activated chloride channels, suggesting a TRPC2-independent pathway for sensing pheromones.
- SangSeong Kim
- , Limei Ma
- & C. Ron Yu
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Molecular basis for class Ib anti-arrhythmic inhibition of cardiac sodium channels
Class I anti-arrhythmic drugs act at cardiac sodium channels and are subdivided into classes Ia-c based on their effects on the electrocardiogram. Here, class Ib drugs are found to rely on cation–pi interactions for their activity, whereas class Ib and Ic drugs rely significantly less on this interaction.
- Stephan A. Pless
- , Jason D. Galpin
- & Christopher A. Ahern
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The neural circuits and sensory channels mediating harsh touch sensation in Caenorhabditis elegans
The mechanisms by which animals distinguish between harsh and gentle touch are unclear. UsingCaenorhabditis elegansas a model system, the authors identify neural circuits and touch-sensitive ion channels that are required for harsh touch sensation.
- Wei Li
- , Lijun Kang
- & X.Z. Shawn Xu
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Ligand-specific deactivation time course of GluN1/GluN2D NMDA receptors
N-methyl-D-aspartate receptors mediate excitatory synaptic transmission, and those containing GluN2D subunits have an unusually long deactivation time. Vance et al. show that the conformational variability of the ligand-binding domain and the structure of the activating ligand influence deactivation time.
- Katie M. Vance
- , Noriko Simorowski
- & Hiro Furukawa
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| Open AccessRespiratory distress and perinatal lethality in Nedd4-2-deficient mice
In vitrostudies have suggested that the ubiquitin ligase, Nedd4-2, regulates several proteins, including the epithelial sodium channel. Here by examining Nedd4-2-deficient mice, the authors demonstrate that Nedd4-2 is essential for epithelial sodium channel regulation, fetal and postnatal lung function and animal survival.
- Natasha A. Boase
- , Grigori Y. Rychkov
- & Sharad Kumar
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| Open AccessLipid-dependent gating of a voltage-gated potassium channel
Lipid phosphodiesters affect the conformation of certain potassium channels, but the details of the lipid-channel interactions are unclear. Here, the KvAP channel is found to switch from an active to a resting state when the channels are transferred from a phospholipid membrane to a bilayer lacking phosphodiesters.
- Hui Zheng
- , Weiran Liu
- & Qiu-Xing Jiang
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| Open AccessErrors in the measurement of voltage-activated ion channels in cell-attached patch-clamp recordings
Voltage-activated ion channels can be measured in neurons using the cell-attached patch-clamp technique. Williams and Wozny show that this technique is prone to errors that are caused by the flow of current through the ion channels; a method to correct for these discrepancies is described.
- Stephen R. Williams
- & Christian Wozny
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A novel gene required for male fertility and functional CATSPER channel formation in spermatozoa
The CATSPER heteromeric ion channel complex is required for male fertility and six protein components of the complex have been identified. In this study, the authors identify a seventh gene, CATSPERδ, which is necessary for functional CatSper channels and hyperactivated sperm motility.
- Jean-Ju Chung
- , Betsy Navarro
- & David E. Clapham
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| Open AccessTRPM7 is essential for Mg2+ homeostasis in mammals
Magnesium is an essential element of the diet and is a cofactor for many enzymes. In this study, the channel kinase TRPM7 is shown to be essential for magnesium homeostasis, and heterozygous mice lacking the kinase domain show a defect in absorption of magnesium from the diet.
- Lillia V. Ryazanova
- , Lusliany J. Rondon
- & Alexey G. Ryazanov
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A subunit-selective potentiator of NR2C- and NR2D-containing NMDA receptors
NMDA receptors are complexes of NR1 and NR2 subunits that mediate excitatory synaptic transmission and have roles in neurological disorders. Here, a subunit-selective potentiator of NMDA receptors is identified, which may allow the evaluation of the functional roles of individual NMDA receptor subunits.
- Praseeda Mullasseril
- , Kasper B. Hansen
- & Stephen F. Traynelis
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| Open AccessPore-opening mechanism in trimeric P2X receptor channels
A recent X-ray structure revealed the closed state of a P2X receptor ion channel. Here, Li and colleagues probe the structural rearrangements that take place during channel opening by measuring the effects of covalent modification of engineered cysteines.
- Mufeng Li
- , Toshimitsu Kawate
- & Kenton J. Swartz