1
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Sánchez-Hernández R, Benítez-Angeles M, Hernández-Vega AM, Rosenbaum T. Recent advances on the structure and the function relationships of the TRPV4 ion channel. Channels (Austin) 2024; 18:2313323. [PMID: 38354101 PMCID: PMC10868539 DOI: 10.1080/19336950.2024.2313323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 01/18/2024] [Indexed: 02/16/2024] Open
Abstract
The members of the superfamily of Transient Receptor Potential (TRP) ion channels are physiologically important molecules that have been studied for many years and are still being intensively researched. Among the vanilloid TRP subfamily, the TRPV4 ion channel is an interesting protein due to its involvement in several essential physiological processes and in the development of various diseases. As in other proteins, changes in its function that lead to the development of pathological states, have been closely associated with modification of its regulation by different molecules, but also by the appearance of mutations which affect the structure and gating of the channel. In the last few years, some structures for the TRPV4 channel have been solved. Due to the importance of this protein in physiology, here we discuss the recent progress in determining the structure of the TRPV4 channel, which has been achieved in three species of animals (Xenopus tropicalis, Mus musculus, and Homo sapiens), highlighting conserved features as well as key differences among them and emphasizing the binding sites for some ligands that play crucial roles in its regulation.
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Affiliation(s)
- Raúl Sánchez-Hernández
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico, Mexico
| | - Miguel Benítez-Angeles
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico, Mexico
| | - Ana M. Hernández-Vega
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico, Mexico
| | - Tamara Rosenbaum
- Departamento de Neurociencia Cognitiva, División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico, Mexico
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2
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Abdelaziz R, Tomczak AP, Neef A, Pardo LA. Revealing a hidden conducting state by manipulating the intracellular domains in K V10.1 exposes the coupling between two gating mechanisms. eLife 2024; 12:RP91420. [PMID: 39259196 DOI: 10.7554/elife.91420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2024] Open
Abstract
The KCNH family of potassium channels serves relevant physiological functions in both excitable and non-excitable cells, reflected in the massive consequences of mutations or pharmacological manipulation of their function. This group of channels shares structural homology with other voltage-gated K+ channels, but the mechanisms of gating in this family show significant differences with respect to the canonical electromechanical coupling in these molecules. In particular, the large intracellular domains of KCNH channels play a crucial role in gating that is still only partly understood. Using KCNH1(KV10.1) as a model, we have characterized the behavior of a series of modified channels that could not be explained by the current models. With electrophysiological and biochemical methods combined with mathematical modeling, we show that the uncovering of an open state can explain the behavior of the mutants. This open state, which is not detectable in wild-type channels, appears to lack the rapid flicker block of the conventional open state. Because it is accessed from deep closed states, it elucidates intermediate gating events well ahead of channel opening in the wild type. This allowed us to study gating steps prior to opening, which, for example, explain the mechanism of gating inhibition by Ca2+-Calmodulin and generate a model that describes the characteristic features of KCNH channels gating.
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Affiliation(s)
- Reham Abdelaziz
- Oncophysiology Group. Max Planck Institute for Multidisciplinary Sciences, City Campus, Göttingen, Germany
| | - Adam P Tomczak
- Oncophysiology Group. Max Planck Institute for Multidisciplinary Sciences, City Campus, Göttingen, Germany
| | - Andreas Neef
- Neurophysics Laboratory, Göttingen Campus Institute for Dynamics of Biological Networks, Göttingen, Germany
| | - Luis A Pardo
- Oncophysiology Group. Max Planck Institute for Multidisciplinary Sciences, City Campus, Göttingen, Germany
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3
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Huang J, Pan X, Yan N. Structural biology and molecular pharmacology of voltage-gated ion channels. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00763-7. [PMID: 39103479 DOI: 10.1038/s41580-024-00763-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2024] [Indexed: 08/07/2024]
Abstract
Voltage-gated ion channels (VGICs), including those for Na+, Ca2+ and K+, selectively permeate ions across the cell membrane in response to changes in membrane potential, thus participating in physiological processes involving electrical signalling, such as neurotransmission, muscle contraction and hormone secretion. Aberrant function or dysregulation of VGICs is associated with a diversity of neurological, psychiatric, cardiovascular and muscular disorders, and approximately 10% of FDA-approved drugs directly target VGICs. Understanding the structure-function relationship of VGICs is crucial for our comprehension of their working mechanisms and role in diseases. In this Review, we discuss how advances in single-particle cryo-electron microscopy have afforded unprecedented structural insights into VGICs, especially on their interactions with clinical and investigational drugs. We present a comprehensive overview of the recent advances in the structural biology of VGICs, with a focus on how prototypical drugs and toxins modulate VGIC activities. We explore how these structures elucidate the molecular basis for drug actions, reveal novel pharmacological sites, and provide critical clues to future drug discovery.
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Affiliation(s)
- Jian Huang
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Xiaojing Pan
- Institute of Bio-Architecture and Bio-Interactions (IBABI), Shenzhen Medical Academy of Research and Translation (SMART), Shenzhen, Guangdong, China.
| | - Nieng Yan
- Institute of Bio-Architecture and Bio-Interactions (IBABI), Shenzhen Medical Academy of Research and Translation (SMART), Shenzhen, Guangdong, China.
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, China.
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4
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Kim ED, Wu X, Lee S, Tibbs GR, Cunningham KP, Di Zanni E, Perez ME, Goldstein PA, Accardi A, Larsson HP, Nimigean CM. Propofol rescues voltage-dependent gating of HCN1 channel epilepsy mutants. Nature 2024; 632:451-459. [PMID: 39085604 DOI: 10.1038/s41586-024-07743-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 06/20/2024] [Indexed: 08/02/2024]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels1 are essential for pacemaking activity and neural signalling2,3. Drugs inhibiting HCN1 are promising candidates for management of neuropathic pain4 and epileptic seizures5. The general anaesthetic propofol (2,6-di-iso-propylphenol) is a known HCN1 allosteric inhibitor6 with unknown structural basis. Here, using single-particle cryo-electron microscopy and electrophysiology, we show that propofol inhibits HCN1 by binding to a mechanistic hotspot in a groove between the S5 and S6 transmembrane helices. We found that propofol restored voltage-dependent closing in two HCN1 epilepsy-associated polymorphisms that act by destabilizing the channel closed state: M305L, located in the propofol-binding site in S5, and D401H in S6 (refs. 7,8). To understand the mechanism of propofol inhibition and restoration of voltage-gating, we tracked voltage-sensor movement in spHCN channels and found that propofol inhibition is independent of voltage-sensor conformational changes. Mutations at the homologous methionine in spHCN and an adjacent conserved phenylalanine in S6 similarly destabilize closing without disrupting voltage-sensor movements, indicating that voltage-dependent closure requires this interface intact. We propose a model for voltage-dependent gating in which propofol stabilizes coupling between the voltage sensor and pore at this conserved methionine-phenylalanine interface in HCN channels. These findings unlock potential exploitation of this site to design specific drugs targeting HCN channelopathies.
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Affiliation(s)
- Elizabeth D Kim
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Xiaoan Wu
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Sangyun Lee
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Gareth R Tibbs
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Kevin P Cunningham
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
- School of Life Sciences, University of Westminster, London, UK
| | - Eleonora Di Zanni
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Marta E Perez
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Peter A Goldstein
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Alessio Accardi
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA
| | - H Peter Larsson
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA.
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden.
| | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA.
- Department of Physiology and Biophysics, Weill Cornell Medical College, New York, NY, USA.
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5
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Stevens-Sostre WA, Flores-Aldama L, Bustos D, Li J, Morais-Cabral JH, Delemotte L, Robertson GA. An intracellular hydrophobic nexus critical for hERG1 channel slow deactivation. Biophys J 2024; 123:2024-2037. [PMID: 38219015 PMCID: PMC11309987 DOI: 10.1016/j.bpj.2024.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/17/2023] [Accepted: 01/09/2024] [Indexed: 01/15/2024] Open
Abstract
Slow deactivation is a critical property of voltage-gated K+ channels encoded by the human Ether-à-go-go-Related Gene 1 (hERG). hERG1 channel deactivation is modulated by interactions between intracellular N-terminal Per-Arnt-Sim (PAS) and C-terminal cyclic nucleotide-binding homology (CNBh) domains. The PAS domain is multipartite, comprising a globular domain (gPAS; residues 26-135) and an N-terminal PAS-cap that is further subdivided into an initial unstructured "tip" (residues 1-12) and an amphipathic α-helical region (residues 13-25). Although the PAS-cap tip has long been considered the effector of slow deactivation, how its position near the gating machinery is controlled has not been elucidated. Here, we show that a triad of hydrophobic interactions among the gPAS, PAS-cap α helix, and the CNBh domains is required to support slow deactivation in hERG1. The primary sequence of this "hydrophobic nexus" is highly conserved among mammalian ERG channels but shows key differences to fast-deactivating Ether-à-go-go 1 (EAG1) channels. Combining sequence analysis, structure-directed mutagenesis, electrophysiology, and molecular dynamics simulations, we demonstrate that polar serine substitutions uncover an intermediate deactivation mode that is also mimicked by deletion of the PAS-cap α helix. Molecular dynamics simulation analyses of the serine-substituted channels show an increase in distance among the residues of the hydrophobic nexus, a rotation of the intracellular gating ring, and a retraction of the PAS-cap tip from its receptor site near the voltage sensor domain and channel gate. These findings provide compelling evidence that the hydrophobic nexus coordinates the respective components of the intracellular gating ring and positions the PAS-cap tip to control hERG1 deactivation gating.
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Affiliation(s)
- Whitney A Stevens-Sostre
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Lisandra Flores-Aldama
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Daniel Bustos
- Centro de Investigación de Estudios Avanzados Del Maule (CIEAM), Vicerrectoría de Investigación y Postgrado, Universidad Católica Del Maule, Talca, Chile; Laboratorio de Bioinformática y Química Computacional (LBQC), Departamento de Medicina Traslacional, Facultad de Medicina, Universidad Católica Del Maule, Talca, Chile
| | - Jin Li
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - João H Morais-Cabral
- Instituto de Investigação e Inovação Em Saude da Universidade Do Porto (i3S); Instituto de Biologia Molecular e Celular, Universidade Do Porto, Porto, Portugal
| | - Lucie Delemotte
- KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden
| | - Gail A Robertson
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
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6
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Lin JL, Chang Y, Tewari D, Cowgill J, Chanda B. Mapping the contribution of the C-linker domain to gating polarity in CNBD channels. Biophys J 2024; 123:2176-2184. [PMID: 38678368 PMCID: PMC11309966 DOI: 10.1016/j.bpj.2024.04.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/23/2024] [Accepted: 04/22/2024] [Indexed: 04/29/2024] Open
Abstract
Ion channels of the cyclic nucleotide-binding domain (CNBD) family play a crucial role in the regulation of key biological processes, such as photoreception and pacemaking activity in the heart. These channels exhibit high sequence and structural similarity but differ greatly in their functional responses to membrane potential. The CNBD family includes hyperpolarization-activated ion channels and depolarization-activated ether-à-go-go channels. Structural and functional studies show that the differences in the coupling interface between these two subfamilies' voltage-sensing domain and pore domain may underlie their differential response to membrane polarity. However, other structural components may also contribute to defining the polarity differences in activation. Here, we focus on the role of the C-terminal domain, which interacts with elements in both the pore and voltage-sensing domains. By generating a series of chimeras involving the C-terminal domain derived from distant members of the CNBD family, we find that the nature of the C-termini profoundly influences the gating polarity of these ion channels. Scanning mutagenesis of the C-linker region, a helix-turn-helix motif connecting the pore helix to the CNBD, reveals that residues at the intersubunit interface between the C-linkers are crucial for hyperpolarization-dependent activation. These findings highlight the unique and unexpected role of the intersubunit interface of the C-linker region in regulating the gating polarity of voltage-gated ion channels.
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Affiliation(s)
- Jenna L Lin
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri; Graduate Program in Biochemistry, Biophysics, & Structural Biology, Washington University School of Medicine, St. Louis, Missouri
| | - Yongchang Chang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - Debanjan Tewari
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - John Cowgill
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - Baron Chanda
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri; Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri.
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7
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Kunzmann P, Krumbach JH, Saponaro A, Moroni A, Thiel G, Hamacher K. Anisotropic Network Analysis of Open/Closed HCN4 Channel Advocates Asymmetric Subunit Cooperativity in cAMP Modulation of Gating. J Chem Inf Model 2024; 64:4727-4738. [PMID: 38830626 PMCID: PMC11203669 DOI: 10.1021/acs.jcim.4c00360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/07/2024] [Accepted: 05/10/2024] [Indexed: 06/05/2024]
Abstract
Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are opened in an allosteric manner by membrane hyperpolarization and cyclic nucleotides such as cAMP. Because of conflicting reports from experimental studies on whether cAMP binding to the four available binding sites in the channel tetramer operates cooperatively in gating, we employ here a computational approach as a promising route to examine ligand-induced conformational changes after binding to individual sites. By combining an elastic network model (ENM) with linear response theory (LRT) for modeling the apo-holo transition of the cyclic nucleotide-binding domain (CNBD) in HCN channels, we observe a distinct pattern of cooperativity matching the "positive-negative-positive" cooperativity reported from functional studies. This cooperativity pattern is highly conserved among HCN subtypes (HCN4, HCN1), but only to a lesser extent visible in structurally related channels, which are only gated by voltage (KAT1) or cyclic nucleotides (TAX4). This suggests an inherent cooperativity between subunits in HCN channels as part of a ligand-triggered gating mechanism in these channels.
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Affiliation(s)
- Patrick Kunzmann
- Department
of Biology, Computational Biology & Simulation, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Jan H. Krumbach
- Department
of Biology, Computational Biology & Simulation, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Andrea Saponaro
- Department
of Pharmacology and Biomolecular Sciences, University of Milano, via Balzaretti 9, 20133 Milano, Italy
| | - Anna Moroni
- Department
of Biosciences, Ion Channel Biophysics, University of Milan, via Celoria 26, 20133 Milan, Italy
| | - Gerhard Thiel
- Department
of Biology, Membrane Biophysics, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
- Centre
for Synthetic Biology, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Kay Hamacher
- Department
of Biology, Computational Biology & Simulation, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
- Centre
for Synthetic Biology, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
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8
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Burtscher V, Mount J, Huang J, Cowgill J, Chang Y, Bickel K, Chen J, Yuan P, Chanda B. Structural basis for hyperpolarization-dependent opening of human HCN1 channel. Nat Commun 2024; 15:5216. [PMID: 38890331 PMCID: PMC11189445 DOI: 10.1038/s41467-024-49599-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 06/11/2024] [Indexed: 06/20/2024] Open
Abstract
Hyperpolarization and cyclic nucleotide (HCN) activated ion channels are critical for the automaticity of action potentials in pacemaking and rhythmic electrical circuits in the human body. Unlike most voltage-gated ion channels, the HCN and related plant ion channels activate upon membrane hyperpolarization. Although functional studies have identified residues in the interface between the voltage-sensing and pore domain as crucial for inverted electromechanical coupling, the structural mechanisms for this unusual voltage-dependence remain unclear. Here, we present cryo-electron microscopy structures of human HCN1 corresponding to Closed, Open, and a putative Intermediate state. Our structures reveal that the downward motion of the gating charges past the charge transfer center is accompanied by concomitant unwinding of the inner end of the S4 and S5 helices, disrupting the tight gating interface observed in the Closed state structure. This helix-coil transition at the intracellular gating interface accompanies a concerted iris-like dilation of the pore helices and underlies the reversed voltage dependence of HCN channels.
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Affiliation(s)
- Verena Burtscher
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
| | - Jonathan Mount
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jian Huang
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA
| | - John Cowgill
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Yongchang Chang
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
| | - Kathleen Bickel
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA
| | - Peng Yuan
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA.
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA.
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Baron Chanda
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA.
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA.
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA.
- Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO, USA.
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9
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Cheng YJ, Wu Y, Wei HQ, Liao YJ, Qu LP, Pan YH, Liu LJ, Bi WT. A novel mutation in hERG gene associated with azithromycin-induced acquired long QT syndrome. Mol Biol Rep 2024; 51:520. [PMID: 38625436 DOI: 10.1007/s11033-024-09421-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 03/06/2024] [Indexed: 04/17/2024]
Abstract
BACKGROUND Mutations in human ether-à-go-go-related gene (hERG) potassium channels are closely associated with long QT syndrome (LQTS). Previous studies have demonstrated that macrolide antibiotics increase the risk of cardiovascular diseases. To date, the mechanisms underlying acquired LQTS remain elusive. METHODS A novel hERG mutation I1025N was identified in an azithromycin-treated patient with acquired long QT syndrome via Sanger sequencing. The mutant I1025N plasmid was transfected into HEK-293 cells, which were subsequently incubated with azithromycin. The effect of azithromycin and mutant I1025N on the hERG channel was evaluated via western blot, immunofluorescence, and electrophysiology techniques. RESULTS The protein expression of the mature hERG protein was down-regulated, whereas that of the immature hERG protein was up-regulated in mutant I1025N HEK-293 cells. Azithromycin administration resulted in a negative effect on the maturation of the hERG protein. Additionally, the I1025N mutation exerted an inhibitory effect on hERG channel current. Moreover, azithromycin inhibited hERG channel current in a concentration-dependent manner. The I1025N mutation and azithromycin synergistically decreased hERG channel expression and hERG current. However, the I1025N mutation and azithromycin did not alter channel gating dynamics. CONCLUSIONS These findings suggest that hERG gene mutations might be involved in the genetic susceptibility mechanism underlying acquired LQTS induced by azithromycin.
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Affiliation(s)
- Yun-Jiu Cheng
- Department of Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Yang Wu
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Hui-Qiang Wei
- Department of Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
| | - Yi-Jian Liao
- The First Clinical Medical College, Guangdong Medical University, Zhanjiang, China
| | - Li-Ping Qu
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Yue-Han Pan
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China
| | - Li-Juan Liu
- Department of Cardiology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
- NHC Key Laboratory of Assisted Circulation and Vascular Diseases, Sun Yat-sen University, Guangzhou, China.
| | - Wen-Tao Bi
- Department of Cardiovascular Medicine, People's Hospital of Macheng City, Macheng, China.
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10
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Wu X, Cunningham KP, Bruening-Wright A, Pandey S, Larsson HP. Loose Coupling between the Voltage Sensor and the Activation Gate in Mammalian HCN Channels Suggests a Gating Mechanism. Int J Mol Sci 2024; 25:4309. [PMID: 38673895 PMCID: PMC11050684 DOI: 10.3390/ijms25084309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Voltage-gated potassium (Kv) channels and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels share similar structures but have opposite gating polarity. Kv channels have a strong coupling (>109) between the voltage sensor (S4) and the activation gate: when S4s are activated, the gate is open to >80% but, when S4s are deactivated, the gate is open <10-9 of the time. Using noise analysis, we show that the coupling between S4 and the gate is <200 in HCN channels. In addition, using voltage clamp fluorometry, locking the gate open in a Kv channel drastically altered the energetics of S4 movement. In contrast, locking the gate open or decreasing the coupling between S4 and the gate in HCN channels had only minor effects on the energetics of S4 movement, consistent with a weak coupling between S4 and the gate. We propose that this loose coupling is a prerequisite for the reversed voltage gating in HCN channels.
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Affiliation(s)
- Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (X.W.); (K.P.C.)
| | - Kevin P. Cunningham
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (X.W.); (K.P.C.)
- School of Life Sciences, University of Westminster, London W1W 6UW, UK
| | | | - Shilpi Pandey
- Oregan National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA;
| | - H. Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; (X.W.); (K.P.C.)
- Department of Biomedical and Clinical Sciences, Linköping University, 58185 Linköping, Sweden
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11
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Das A, Bysack A, Raghuraman H. Cholesterol modulates the structural dynamics of the paddle motif loop of KvAP voltage sensor. Curr Res Struct Biol 2024; 7:100137. [PMID: 38500801 PMCID: PMC10945132 DOI: 10.1016/j.crstbi.2024.100137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/29/2024] [Accepted: 03/03/2024] [Indexed: 03/20/2024] Open
Abstract
KvAP is a prokaryotic Kv channel, which has been widely used as a model system to understand voltage- and lipid-dependent gating mechanisms. In phospholipid membranes, the KvAP-VSD adopts the activated/'Up' conformation, whereas the presence of non-phospholipids in membranes favours the structural transition to resting/'Down' state. The S3b-S4 paddle motif loop of KvAP-VSD is functionally important as this participates in protein-protein interactions and is the target for animal toxins. In this study, we have monitored the modulatory role of cholesterol - the physiologically-relevant non-phospholipid - on the organization and dynamics of the S3b-S4 loop of the isolated KvAP-VSD in membranes by site-directed fluorescence approaches using the environmental sensitivity of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-ethylenediamine (NBD) fluorescence. Our results show that cholesterol alters the dynamic nature (rotational and hydration dynamics) of S3b-S4 loop in a segmental fashion, i.e., the residues 110 to 114 and 115 to 117 behave differently in the presence of cholesterol, which is accompanied by considerable change in conformational heterogeneity. Further, quantitative depth measurements using the parallax quenching method reveal that the sensor loop is located at the shallow interfacial region of cholesterol-containing membranes, suggesting that the sensor loop organization is not directly correlated with S4 helix movement. Our results clearly show that cholesterol-induced changes in bilayer properties may not be the predominant factor for the sensor loop's altered structural dynamics, but can be attributed to the conformational change of the KvAP-VSD in cholesterol-containing membranes. Overall, these results are relevant for gating mechanisms, particularly the lipid-dependent gating, of Kv channels in membranes.
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Affiliation(s)
- Anindita Das
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - Arpan Bysack
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
| | - H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, 400 094, India
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12
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Ma B, Shi S, Guo W, Zhang H, Zhao Z, An H. Liensinine, a Novel and Food-Derived Compound, Exerts Potent Antihepatoma Efficacy via Inhibiting the Kv10.1 Channel. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:4689-4702. [PMID: 38382537 DOI: 10.1021/acs.jafc.3c06142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Plant metabolites from natural product extracts offer unique advantages against carcinogenesis in the development of drugs. The target-based virtual screening from food-derived compounds represents a promising approach for tumor therapy. In this study, we performed virtual screening to target the presumed inhibitor-binding pocket and identified a highly potent Kv10.1 inhibitor, liensinine (Lien), which can inhibit the channel in a dose-dependent way with an IC50 of 0.24 ± 0.07 μM. Combining molecular dynamics simulations with mutagenesis experiments, our data show that Lien interacts with Kv10.1 by binding with Y539, T543, D551, E553, and H601 in the C-linker domain of Kv10.1. In addition, the interaction of sequence alignment and 3D structural modeling revealed differences between the C-linker domain of the Kv10.1 channel and the Kv11.1 channel. Furthermore, antitumor experiments revealed that Lien suppresses the proliferation and migration of HCC both in vitro and in vivo. In summary, the food-derived compound, Lien, may serve as a lead compound for antihepatoma therapeutic drugs targeting Kv10.1.
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Affiliation(s)
- Biao Ma
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China
- Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Sai Shi
- Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, Tianjin 300072, China
| | - Wei Guo
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Zhen Zhao
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
| | - Hailong An
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300401, China
- Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin 300401, China
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Health Sciences & Biomedical Engineering, Hebei University of Technology, Tianjin 300401, China
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13
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Gomez-Lagunas F, Barriga-Montoya C, Pardo JP. State-independent inhibition of the oncogenic Kv10.1 channel by desethylamiodarone, a comparison with amiodarone. Pflugers Arch 2024; 476:323-335. [PMID: 38063872 PMCID: PMC10847070 DOI: 10.1007/s00424-023-02893-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/28/2023] [Accepted: 11/24/2023] [Indexed: 02/08/2024]
Abstract
Kv10.1 is a voltage-dependent K channel whose ectopic expression is associated with several human cancers. Additionally, Kv10.1 has structure-function properties which are not yet well understood. We are using drugs of clinical importance in an attempt to gain insight on the relationship between pharmacology and characteristic functional properties of this channel. Herein, we report the interaction of desethylamiodarone (desAd), the active metabolic product of the antiarrhythmic amiodarone with Kv10.1: desAd binds to both closed and open channels, with most inhibition taking place from the open state, with affinity ~ 5 times smaller than that of amiodarone. Current inhibition by desAd and amiodarone is not synergistic. Upon repolarization desAd becomes trapped in Kv10.1 and thereafter dissociates slowly from closed-and-blocked channels. The addition of the Cole-Moore shift plus desAd open-pore-block time courses yields an increasing phase on the steady-state inhibition curve (H∞) at hyperpolarized holding potentials. In contrast to amiodarone, desAd does not inhibit the Kv10.1 Cole-Moore shift, suggesting that a relevant hydrophobic interaction between amiodarone and Kv10.1 participates in the inhibition of the Cole-Moore shift, which is lost with desAd.
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Affiliation(s)
- F Gomez-Lagunas
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico City, México.
| | - C Barriga-Montoya
- Department of Physiology, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico City, México
| | - J P Pardo
- Department of Biochemistry, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico City, México
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14
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Ghorbani M, Wang ZJ, Chen X, Tiwari PB, Klauda JB, Brelidze TI. Chlorpromazine inhibits EAG1 channels by altering the coupling between the PAS, CNBH and pore domains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.23.581826. [PMID: 38464246 PMCID: PMC10925124 DOI: 10.1101/2024.02.23.581826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
EAG1 depolarization-activated potassium selective channels are important targets for treatment of cancer and neurological disorders. EAG1 channels are formed by a tetrameric subunit assembly with each subunit containing an N-terminal Per-Arnt-Sim (PAS) domain and C-terminal cyclic nucleotide-binding homology (CNBH) domain. The PAS and CNBH domains from adjacent subunits interact and form an intracellular tetrameric ring that regulates the EAG1 channel gating, including the movement of the voltage sensor domain (VSD) from closed to open states. Small molecule ligands can inhibit EAG1 channels by binding to their PAS domains. However, the allosteric pathways of this inhibition are not known. Here we show that chlorpromazine, a PAS domain small molecule binder, alters interactions between the PAS and CNBH domains and decreases the coupling between the intracellular tetrameric ring and the pore of the channel, while having little effect on the coupling between the PAS and VSD domains. In addition, chlorpromazine binding to the PAS domain did not alter Cole-Moore shift characteristic of EAG1 channels, further indicating that chlorpromazine has no effect on VSD movement from the deep closed to opened states. Our study provides a framework for understanding global pathways of EAG1 channel regulation by small molecule PAS domain binders.
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15
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González-González MA, Conde SV, Latorre R, Thébault SC, Pratelli M, Spitzer NC, Verkhratsky A, Tremblay MÈ, Akcora CG, Hernández-Reynoso AG, Ecker M, Coates J, Vincent KL, Ma B. Bioelectronic Medicine: a multidisciplinary roadmap from biophysics to precision therapies. Front Integr Neurosci 2024; 18:1321872. [PMID: 38440417 PMCID: PMC10911101 DOI: 10.3389/fnint.2024.1321872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/10/2024] [Indexed: 03/06/2024] Open
Abstract
Bioelectronic Medicine stands as an emerging field that rapidly evolves and offers distinctive clinical benefits, alongside unique challenges. It consists of the modulation of the nervous system by precise delivery of electrical current for the treatment of clinical conditions, such as post-stroke movement recovery or drug-resistant disorders. The unquestionable clinical impact of Bioelectronic Medicine is underscored by the successful translation to humans in the last decades, and the long list of preclinical studies. Given the emergency of accelerating the progress in new neuromodulation treatments (i.e., drug-resistant hypertension, autoimmune and degenerative diseases), collaboration between multiple fields is imperative. This work intends to foster multidisciplinary work and bring together different fields to provide the fundamental basis underlying Bioelectronic Medicine. In this review we will go from the biophysics of the cell membrane, which we consider the inner core of neuromodulation, to patient care. We will discuss the recently discovered mechanism of neurotransmission switching and how it will impact neuromodulation design, and we will provide an update on neuronal and glial basis in health and disease. The advances in biomedical technology have facilitated the collection of large amounts of data, thereby introducing new challenges in data analysis. We will discuss the current approaches and challenges in high throughput data analysis, encompassing big data, networks, artificial intelligence, and internet of things. Emphasis will be placed on understanding the electrochemical properties of neural interfaces, along with the integration of biocompatible and reliable materials and compliance with biomedical regulations for translational applications. Preclinical validation is foundational to the translational process, and we will discuss the critical aspects of such animal studies. Finally, we will focus on the patient point-of-care and challenges in neuromodulation as the ultimate goal of bioelectronic medicine. This review is a call to scientists from different fields to work together with a common endeavor: accelerate the decoding and modulation of the nervous system in a new era of therapeutic possibilities.
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Affiliation(s)
- María Alejandra González-González
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, United States
- Department of Pediatric Neurology, Baylor College of Medicine, Houston, TX, United States
| | - Silvia V. Conde
- iNOVA4Health, NOVA Medical School, Faculdade de Ciências Médicas, NOVA University, Lisbon, Portugal
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Stéphanie C. Thébault
- Laboratorio de Investigación Traslacional en salud visual (D-13), Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
| | - Marta Pratelli
- Neurobiology Department, Kavli Institute for Brain and Mind, UC San Diego, La Jolla, CA, United States
| | - Nicholas C. Spitzer
- Neurobiology Department, Kavli Institute for Brain and Mind, UC San Diego, La Jolla, CA, United States
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
- Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
- Department of Forensic Analytical Toxicology, School of Forensic Medicine, China Medical University, Shenyang, China
- International Collaborative Center on Big Science Plan for Purinergic Signaling, Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Department of Stem Cell Biology, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Department of Molecular Medicine, Université Laval, Québec City, QC, Canada
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Cuneyt G. Akcora
- Department of Computer Science, University of Central Florida, Orlando, FL, United States
| | | | - Melanie Ecker
- Department of Biomedical Engineering, University of North Texas, Denton, TX, United States
| | | | - Kathleen L. Vincent
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX, United States
| | - Brandy Ma
- Stanley H. Appel Department of Neurology, Houston Methodist Hospital, Houston, TX, United States
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16
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Liu J, Lu J, Ji W, Lu G, Wang J, Ye T, Jiang Y, Zheng J, Yu P, Liu N, Jiang Y, Mao L. Ion-Selective Micropipette Sensor for In Vivo Monitoring of Sodium Ion with Crown Ether-Encapsulated Metal-Organic Framework Subnanopores. Anal Chem 2024; 96:2651-2657. [PMID: 38306178 DOI: 10.1021/acs.analchem.3c05366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
In vivo sensing of the dynamics of ions with high selectivity is essential for gaining molecular insights into numerous physiological and pathological processes. In this work, we report an ion-selective micropipette sensor (ISMS) through the integration of functional crown ether-encapsulated metal-organic frameworks (MOFs) synthesized in situ within the micropipette tip. The ISMS features distinctive sodium ion (Na+) conduction and high selectivity toward Na+ sensing. The selectivity is attributed to the synergistic effects of subnanoconfined space and the specific coordination of 18-crown-6 toward potassium ions (K+), which largely increase the steric hindrance and transport resistance for K+ to pass through the ISMS. Furthermore, the ISMS exhibits high stability and sensitivity, facilitating real-time monitoring of Na+ dynamics in the living rat brain during spreading of the depression events process. In light of the diversity of crown ethers and MOFs, we believe this study paves the way for a nanofluidic platform for in vivo sensing and neuromorphic electrochemical sensing.
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Affiliation(s)
- Jiahao Liu
- Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jiahao Lu
- College of Chemistry, Beijing Normal University, Beijing 100875, China
- Beijing National Laboratory for Molecular Science, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Wenliang Ji
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Guangwen Lu
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jiao Wang
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Tingyan Ye
- Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China
| | - Yisha Jiang
- Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China
| | - Juanjuan Zheng
- Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China
| | - Ping Yu
- Beijing National Laboratory for Molecular Science, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Nannan Liu
- Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325027, China
| | - Yanan Jiang
- College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Lanqun Mao
- College of Chemistry, Beijing Normal University, Beijing 100875, China
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17
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Ma B, Shi S, Ren S, Qu C, Zhao Z, An H. Corydaline binds to a druggable pocket of hEAG1 channel and inhibits hepatic carcinoma cell viability. Eur J Pharmacol 2024; 962:176240. [PMID: 38048981 DOI: 10.1016/j.ejphar.2023.176240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 11/22/2023] [Accepted: 11/28/2023] [Indexed: 12/06/2023]
Abstract
Ether-à-go-go (EAG) potassium channels play a crucial role in the regulation of neuronal excitability and cancer progression, rendering them potential drug targets for cancer therapy. However, the scarcity of information regarding the selection sites on hEAG1 has posed a challenge in the discovery of new hEAG1 inhibitors. In this study, we introduced a novel natural product, corydaline, which selectively inhibits the hEAG1 channel without sensitivity to other KCNH channels. The IC50 of corydaline for the hEAG1 channel was 11.3 ± 0.6 μM, whereas the IC50 for hEAG2 and hERG1 were 73.6 ± 9.9 μM and 111.4 ± 8.5 μM, respectively. Molecular dynamics simulations together with site-directed mutagenesis, have unveiled that the site corydaline forms interactions with Lys217, Phe273, Pro276, Trp295 and Arg366, situated within the intracellular transmembrane segments S1-S4 of the voltage-sensor domain, be considered a novel drug pocket for hEAG1. Additionally, the intergaration of sequence alignment and 3D structural modeling revealed differences between the voltage sensor domain of hEAG1 channel and other EAG channels, suggesting the feasibility of a VSD modulation approach that could potentially lead to the selective inhibition of hEAG1 channels. Furthermore, antitumor experiments demonstrated that corydaline can inhibit the proliferation and migration of hepatic carcinoma cells by targeting hEAG1. The identification of this novel druggable pocket offers the possibility for drug screening against diseases linked to abnormal hEAG1 channels.
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Affiliation(s)
- Biao Ma
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, 300401, China; Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin, 300401, China; Key Laboratory of Molecular Biophysics, Hebei Province, China; Institute of Biophysics, School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Sai Shi
- Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, Tianjin, 300072, China
| | - Shuxi Ren
- School of Sciences, Hebei University of Technology, Tianjin, 300401, China
| | - Chang Qu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, 300401, China; Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin, 300401, China; Key Laboratory of Molecular Biophysics, Hebei Province, China; Institute of Biophysics, School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Zhen Zhao
- Key Laboratory of Molecular Biophysics, Hebei Province, China; Institute of Biophysics, School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin, 300401, China.
| | - Hailong An
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin, 300401, China; Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability of Hebei Province, Hebei University of Technology, Tianjin, 300401, China; Key Laboratory of Molecular Biophysics, Hebei Province, China; Institute of Biophysics, School of Health Sciences and Biomedical Engineering, Hebei University of Technology, Tianjin, 300401, China.
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18
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Glukhov G, Karlova M, Kravchuk E, Glukhova A, Trifonova E, Sokolova OS. Purification of Potassium Ion Channels Using Styrene-Maleic Acid Copolymers. Methods Mol Biol 2024; 2796:73-86. [PMID: 38856895 DOI: 10.1007/978-1-0716-3818-7_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Structural studies require the production of target proteins in large quantities and with a high degree of purity. For membrane proteins, the bottleneck in determining their structure is the extraction of the target protein from the cell membranes. A detergent that improperly mimics the hydrophobic environment of the protein of interest can also significantly alter its structure. Recently, using lipodiscs with styrene-maleic acid (SMA), copolymers became a promising strategy for the purification of membrane proteins. Here, we describe in detail the one-step affinity purification of potassium ion channels solubilized in SMA and sample preparation for future structural studies.
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Affiliation(s)
- Grigory Glukhov
- Faculty of Biology, Shenzhen MSU-BIT University, Shenzhen, China
| | - Maria Karlova
- Faculty of Biology, Moscow Lomonosov University, Moscow, Russia
| | | | - Anna Glukhova
- Faculty of Biology, Shenzhen MSU-BIT University, Shenzhen, China
| | | | - Olga S Sokolova
- Faculty of Biology, Shenzhen MSU-BIT University, Shenzhen, China.
- Faculty of Biology, Moscow Lomonosov University, Moscow, Russia.
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19
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Tiwari PB, Kamgar-Dayhoff P, Tiwari P, McKillop MI, Brelidze TI. Use of Surface Plasmon Resonance Technique for Studies of Inter-domain Interactions in Ion Channels. Methods Mol Biol 2024; 2796:105-118. [PMID: 38856898 PMCID: PMC11225882 DOI: 10.1007/978-1-0716-3818-7_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Ion channels are transmembrane proteins essential for cellular functions and are important drug targets. Surface plasmon resonance (SPR) is a powerful technique for investigating protein-protein and protein-small molecule ligand interactions. SPR has been underutilized for studies of ion channels, even though it could provide a wealth of information on the mechanisms of ion channel regulation and aid in ion channel drug discovery. Here we provide a detailed description of the use of SPR technology for investigating inter-domain interactions in KCNH potassium-selective and voltage-gated ion channels.
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Affiliation(s)
- Purushottam B Tiwari
- Department of Oncology, Georgetown University Medical Center, Washington, DC, USA
| | - Pareesa Kamgar-Dayhoff
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, USA
| | - Prakriti Tiwari
- Department of Oncology, Georgetown University Medical Center, Washington, DC, USA
- Department of Biology, College of Arts & Sciences, Georgetown University, Washington, DC, USA
| | - Maria I McKillop
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, USA
| | - Tinatin I Brelidze
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, USA.
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20
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Wang ZJ, Ghorbani M, Chen X, Tiwari PB, Klauda JB, Brelidze TI. Molecular mechanism of EAG1 channel inhibition by imipramine binding to the PAS domain. J Biol Chem 2023; 299:105391. [PMID: 37898402 PMCID: PMC10687071 DOI: 10.1016/j.jbc.2023.105391] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/17/2023] [Accepted: 10/19/2023] [Indexed: 10/30/2023] Open
Abstract
Ether-a-go-go (EAG) channels are key regulators of neuronal excitability and tumorigenesis. EAG channels contain an N-terminal Per-Arnt-Sim (PAS) domain that can regulate currents from EAG channels by binding small molecules. The molecular mechanism of this regulation is not clear. Using surface plasmon resonance and electrophysiology we show that a small molecule ligand imipramine can bind to the PAS domain of EAG1 channels and inhibit EAG1 currents via this binding. We further used a combination of molecular dynamics (MD) simulations, electrophysiology, and mutagenesis to investigate the molecular mechanism of EAG1 current inhibition by imipramine binding to the PAS domain. We found that Tyr71, located at the entrance to the PAS domain cavity, serves as a "gatekeeper" limiting access of imipramine to the cavity. MD simulations indicate that the hydrophobic electrostatic profile of the cavity facilitates imipramine binding and in silico mutations of hydrophobic cavity-lining residues to negatively charged glutamates decreased imipramine binding. Probing the PAS domain cavity-lining residues with site-directed mutagenesis, guided by MD simulations, identified D39 and R84 as residues essential for the EAG1 channel inhibition by imipramine binding to the PAS domain. Taken together, our study identified specific residues in the PAS domain that could increase or decrease EAG1 current inhibition by imipramine binding to the PAS domain. These findings should further the understanding of molecular mechanisms of EAG1 channel regulation by ligands and facilitate the development of therapeutic agents targeting these channels.
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Affiliation(s)
- Ze-Jun Wang
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Mahdi Ghorbani
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, USA
| | - Xi Chen
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Purushottam B Tiwari
- Department of Oncology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, USA; Institute for Physical Science and Technology and Biophysics Graduate Program, University of Maryland, College Park, Maryland, USA.
| | - Tinatin I Brelidze
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia, USA.
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21
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Spafford JD. A governance of ion selectivity based on the occupancy of the "beacon" in one- and four-domain calcium and sodium channels. Channels (Austin) 2023; 17:2191773. [PMID: 37075164 PMCID: PMC10120453 DOI: 10.1080/19336950.2023.2191773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023] Open
Abstract
One of nature's exceptions was discovered when a Cav3 T-type channel was observed to switch phenotype from a calcium channel into a sodium channel by neutralizing an aspartate residue in the high field strength (HFS) +1 position within the ion selectivity filter. The HFS+1 site is dubbed a "beacon" for its location at the entryway just above the constricted, minimum radius of the HFS site's electronegative ring. A classification is proposed based on the occupancy of the HFS+1 "beacon" which correlates with the calcium- or sodium-selectivity phenotype. If the beacon is a glycine, or neutral, non-glycine residue, then the cation channel is calcium-selective or sodium-permeable, respectively (Class I). Occupancy of a beacon aspartate are calcium-selective channels (Class II) or possessing a strong calcium block (Class III). A residue lacking in position of the sequence alignment for the beacon are sodium channels (Class IV). The extent to which animal channels are sodium-selective is dictated in the occupancy of the HFS site with a lysine residue (Class III/IV). Governance involving the beacon solves the quandary the HFS site as a basis for ion selectivity, where an electronegative ring of glutamates at the HFS site generates a sodium-selective channel in one-domain channels but generates a calcium-selective channel in four-domain channels. Discovery of a splice variant in an exceptional channel revealed nature's exploits, highlighting the "beacon" as a principal determinant for calcium and sodium selectivity, encompassing known ion channels composed of one and four domains, from bacteria to animals.
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Affiliation(s)
- J David Spafford
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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22
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Chandy KG, Sanches K, Norton RS. Structure of the voltage-gated potassium channel K V1.3: Insights into the inactivated conformation and binding to therapeutic leads. Channels (Austin) 2023; 17:2253104. [PMID: 37695839 PMCID: PMC10496531 DOI: 10.1080/19336950.2023.2253104] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/23/2023] [Accepted: 08/24/2023] [Indexed: 09/13/2023] Open
Abstract
The voltage-gated potassium channel KV1.3 is an important therapeutic target for the treatment of autoimmune and neuroinflammatory diseases. The recent structures of KV1.3, Shaker-IR (wild-type and inactivating W434F mutant) and an inactivating mutant of rat KV1.2-KV2.1 paddle chimera (KVChim-W362F+S367T+V377T) reveal that the transition of voltage-gated potassium channels from the open-conducting conformation into the non-conducting inactivated conformation involves the rupture of a key intra-subunit hydrogen bond that tethers the selectivity filter to the pore helix. Breakage of this bond allows the side chains of residues at the external end of the selectivity filter (Tyr447 and Asp449 in KV1.3) to rotate outwards, dilating the outer pore and disrupting ion permeation. Binding of the peptide dalazatide (ShK-186) and an antibody-ShK fusion to the external vestibule of KV1.3 narrows and stabilizes the selectivity filter in the open-conducting conformation, although K+ efflux is blocked by the peptide occluding the pore through the interaction of ShK-Lys22 with the backbone carbonyl of KV1.3-Tyr447 in the selectivity filter. Electrophysiological studies on ShK and the closely-related peptide HmK show that ShK blocks KV1.3 with significantly higher potency, even though molecular dynamics simulations show that ShK is more flexible than HmK. Binding of the anti-KV1.3 nanobody A0194009G09 to the turret and residues in the external loops of the voltage-sensing domain enhances the dilation of the outer selectivity filter in an exaggerated inactivated conformation. These studies lay the foundation to further define the mechanism of slow inactivation in KV channels and can help guide the development of future KV1.3-targeted immuno-therapeutics.
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Affiliation(s)
- K. George Chandy
- LKCMedicine-ICESing Ion Channel Platform, Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Karoline Sanches
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
| | - Raymond S. Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
- ARC Centre for Fragment-Based Design, Monash University, Parkville, Victoria, Australia
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23
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Emigh Cortez AM, DeMarco KR, Furutani K, Bekker S, Sack JT, Wulff H, Clancy CE, Vorobyov I, Yarov-Yarovoy V. Structural modeling of hERG channel-drug interactions using Rosetta. Front Pharmacol 2023; 14:1244166. [PMID: 38035013 PMCID: PMC10682396 DOI: 10.3389/fphar.2023.1244166] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/23/2023] [Indexed: 12/02/2023] Open
Abstract
The human ether-a-go-go-related gene (hERG) not only encodes a potassium-selective voltage-gated ion channel essential for normal electrical activity in the heart but is also a major drug anti-target. Genetic hERG mutations and blockage of the channel pore by drugs can cause long QT syndrome, which predisposes individuals to potentially deadly arrhythmias. However, not all hERG-blocking drugs are proarrhythmic, and their differential affinities to discrete channel conformational states have been suggested to contribute to arrhythmogenicity. We used Rosetta electron density refinement and homology modeling to build structural models of open-state hERG channel wild-type and mutant variants (Y652A, F656A, and Y652A/F656 A) and a closed-state wild-type channel based on cryo-electron microscopy structures of hERG and EAG1 channels. These models were used as protein targets for molecular docking of charged and neutral forms of amiodarone, nifekalant, dofetilide, d/l-sotalol, flecainide, and moxifloxacin. We selected these drugs based on their different arrhythmogenic potentials and abilities to facilitate hERG current. Our docking studies and clustering provided atomistic structural insights into state-dependent drug-channel interactions that play a key role in differentiating safe and harmful hERG blockers and can explain hERG channel facilitation through drug interactions with its open-state hydrophobic pockets.
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Affiliation(s)
- Aiyana M. Emigh Cortez
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | - Kevin R. DeMarco
- Biophysics Graduate Group, University of California, Davis, Davis, CA, United States
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
| | - Kazuharu Furutani
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Pharmacology, Tokushima Bunri University, Tokushima, Japan
| | - Slava Bekker
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- American River College, Sacramento, CA, United States
| | - Jon T. Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Colleen E. Clancy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
- Center for Precision Medicine and Data Sciences, University of California, Davis, Davis, CA, United States
| | - Igor Vorobyov
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States
- Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA, United States
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24
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Burtscher V, Mount J, Cowgill J, Chang Y, Bickel K, Yuan P, Chanda B. Structural Basis for Hyperpolarization-dependent Opening of the Human HCN1 Channel. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.17.553623. [PMID: 37645882 PMCID: PMC10462129 DOI: 10.1101/2023.08.17.553623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Hyperpolarization and cyclic-nucleotide (HCN) activated ion channels play a critical role in generating self-propagating action potentials in pacemaking and rhythmic electrical circuits in the human body. Unlike most voltage-gated ion channels, the HCN channels activate upon membrane hyperpolarization, but the structural mechanisms underlying this gating behavior remain unclear. Here, we present cryo-electron microscopy structures of human HCN1 in Closed, Intermediate, and Open states. Our structures reveal that the inward motion of two gating charges past the charge transfer center (CTC) and concomitant tilting of the S5 helix drives the opening of the central pore. In the intermediate state structure, a single gating charge is positioned below the CTC and the pore appears closed, whereas in the open state structure, both charges move past CTC and the pore is fully open. Remarkably, the downward motion of the voltage sensor is accompanied by progressive unwinding of the inner end of S4 and S5 helices disrupting the tight gating interface that stabilizes the Closed state structure. This "melting" transition at the intracellular gating interface leads to a concerted iris-like displacement of S5 and S6 helices, resulting in pore opening. These findings reveal key structural features that are likely to underlie reversed voltage-dependence of HCN channels.
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Affiliation(s)
- Verena Burtscher
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Jonathan Mount
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John Cowgill
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Yongchang Chang
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
| | - Kathleen Bickel
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
| | - Peng Yuan
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Baron Chanda
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO, USA
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25
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Costa F, Ocello R, Guardiani C, Giacomello A, Masetti M. Integrated Approach Including Docking, MD Simulations, and Network Analysis Highlights the Action Mechanism of the Cardiac hERG Activator RPR260243. J Chem Inf Model 2023; 63:4888-4899. [PMID: 37504578 PMCID: PMC10428221 DOI: 10.1021/acs.jcim.3c00596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Indexed: 07/29/2023]
Abstract
hERG is a voltage-gated potassium channel involved in the heart contraction whose defections are associated with the cardiac arrhythmia Long QT Syndrome type 2. The activator RPR260243 (RPR) represents a possible candidate to pharmacologically treat LQTS2 because it enhances the opening of the channel. However, the molecular detail of its action mechanism remains quite elusive. Here, we address the problem using a combination of docking, molecular dynamics simulations, and network analysis. We show that the drug preferably binds at the interface between the voltage sensor and the pore, enhancing the canonical activation path and determining a whole-structure rearrangement of the channel that slightly impairs inactivation.
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Affiliation(s)
- Flavio Costa
- Dipartimento
di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, via Eudossiana 18, 00184 Rome, Italy
| | - Riccardo Ocello
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum−Università di Bologna, via Belmeloro 6, 40126 Bologna, Italy
| | - Carlo Guardiani
- Dipartimento
di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, via Eudossiana 18, 00184 Rome, Italy
| | - Alberto Giacomello
- Dipartimento
di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, via Eudossiana 18, 00184 Rome, Italy
| | - Matteo Masetti
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum−Università di Bologna, via Belmeloro 6, 40126 Bologna, Italy
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26
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Catacuzzeno L, Conti F, Franciolini F. Fifty years of gating currents and channel gating. J Gen Physiol 2023; 155:e202313380. [PMID: 37410612 PMCID: PMC10324510 DOI: 10.1085/jgp.202313380] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/12/2023] [Accepted: 06/02/2023] [Indexed: 07/08/2023] Open
Abstract
We celebrate this year the 50th anniversary of the first electrophysiological recordings of the gating currents from voltage-dependent ion channels done in 1973. This retrospective tries to illustrate the context knowledge on channel gating and the impact gating-current recording had then, and how it continued to clarify concepts, elaborate new ideas, and steer the scientific debate in these 50 years. The notion of gating particles and gating currents was first put forward by Hodgkin and Huxley in 1952 as a necessary assumption for interpreting the voltage dependence of the Na and K conductances of the action potential. 20 years later, gating currents were actually recorded, and over the following decades have represented the most direct means of tracing the movement of the gating charges and gaining insights into the mechanisms of channel gating. Most work in the early years was focused on the gating currents from the Na and K channels as found in the squid giant axon. With channel cloning and expression on heterologous systems, other channels as well as voltage-dependent enzymes were investigated. Other approaches were also introduced (cysteine mutagenesis and labeling, site-directed fluorometry, cryo-EM crystallography, and molecular dynamics [MD] modeling) to provide an integrated and coherent view of voltage-dependent gating in biological macromolecules. The layout of this retrospective reflects the past 50 years of investigations on gating currents, first addressing studies done on Na and K channels and then on other voltage-gated channels and non-channel structures. The review closes with a brief overview of how the gating-charge/voltage-sensor movements are translated into pore opening and the pathologies associated with mutations targeting the structures involved with the gating currents.
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Affiliation(s)
- Luigi Catacuzzeno
- Department of Chemistry Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Franco Conti
- Department of Physics, University of Genova, Genova, Italy
| | - Fabio Franciolini
- Department of Chemistry Biology and Biotechnology, University of Perugia, Perugia, Italy
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27
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Gómez-Herrera MA, Patlán E, Estrada-Garrido A, Hernández-Cruz A, Luis E. Fluorescent membrane potential assay for drug screening on Kv10.1 channel: identification of BL-1249 as a channel activator. Front Pharmacol 2023; 14:1238503. [PMID: 37554982 PMCID: PMC10404814 DOI: 10.3389/fphar.2023.1238503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 07/12/2023] [Indexed: 08/10/2023] Open
Abstract
Resting membrane potential is a bioelectric property of all cells. Multiple players govern this property, the ion channels being the most important. Ion channel dysfunction can affect cells' resting membrane potential and could be associated with numerous diseases. Therefore, the drug discovery focus on ion channels has increased yearly. In addition to patch-clamp, cell-based fluorescent assays have shown a rapid and reliable method for searching new ion channel modulators. Here, we used a cell-based membrane potential assay to search for new blockers of the Kv10.1, a potassium channel strongly associated with cancer progression and a promising target in anticancer therapy. We found that fluoxetine and miconazole can inhibit the Kv10.1 channel in the micromolar range. In contrast, BL-1249 potentiates Kv10.1 currents in a dose-dependent manner, becoming the first molecule described as an activator of the channel. These results demonstrate that cell-based membrane potential assay can accelerate the discovery of new Kv10.1 modulators.
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Affiliation(s)
- Mirsha Aseret Gómez-Herrera
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Enikar Patlán
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Armando Estrada-Garrido
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Universidad Tecnológica de México (UNITEC)—Campus Ecatepec, Estado de México, Mexico
| | - Arturo Hernández-Cruz
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Enoch Luis
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Cátedras CONAHCYT—Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
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28
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Li S, Wang Y, Wang C, Zhang Y, Sun D, Zhou P, Tian C, Liu S. Cryo-EM structure reveals a symmetry reduction of the plant outward-rectifier potassium channel SKOR. Cell Discov 2023; 9:67. [PMID: 37391403 DOI: 10.1038/s41421-023-00572-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 05/30/2023] [Indexed: 07/02/2023] Open
Affiliation(s)
- Siyu Li
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, Anhui Engineering Laboratory of Peptide Drug, Anhui Laboratory of Advanced Photonic Science and Technology, University of Science and Technology of China, Hefei, Anhui, China
| | - Yuanxia Wang
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, Anhui Engineering Laboratory of Peptide Drug, Anhui Laboratory of Advanced Photonic Science and Technology, University of Science and Technology of China, Hefei, Anhui, China
| | - Chenyang Wang
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, Anhui Engineering Laboratory of Peptide Drug, Anhui Laboratory of Advanced Photonic Science and Technology, University of Science and Technology of China, Hefei, Anhui, China
| | - Yong Zhang
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, Anhui Engineering Laboratory of Peptide Drug, Anhui Laboratory of Advanced Photonic Science and Technology, University of Science and Technology of China, Hefei, Anhui, China
| | - Demeng Sun
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, Anhui Engineering Laboratory of Peptide Drug, Anhui Laboratory of Advanced Photonic Science and Technology, University of Science and Technology of China, Hefei, Anhui, China
| | - Peng Zhou
- School of Life Science, Hefei Normal University, Hefei, Anhui, China.
| | - Changlin Tian
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, Anhui Engineering Laboratory of Peptide Drug, Anhui Laboratory of Advanced Photonic Science and Technology, University of Science and Technology of China, Hefei, Anhui, China.
- The Anhui Provincial Key Laboratory of High Magnetic Resonance Image, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, China.
| | - Sanling Liu
- Department of Endocrinology, Institute of Endocrine and Metabolic Diseases, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Joint Center for Biological Analytical Chemistry, Anhui Engineering Laboratory of Peptide Drug, Anhui Laboratory of Advanced Photonic Science and Technology, University of Science and Technology of China, Hefei, Anhui, China.
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29
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Chaigne S, Barbeau S, Ducret T, Guinamard R, Benoist D. Pathophysiological Roles of the TRPV4 Channel in the Heart. Cells 2023; 12:1654. [PMID: 37371124 DOI: 10.3390/cells12121654] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/10/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
The transient receptor potential vanilloid 4 (TRPV4) channel is a non-selective cation channel that is mostly permeable to calcium (Ca2+), which participates in intracellular Ca2+ handling in cardiac cells. It is widely expressed through the body and is activated by a large spectrum of physicochemical stimuli, conferring it a role in a variety of sensorial and physiological functions. Within the cardiovascular system, TRPV4 expression is reported in cardiomyocytes, endothelial cells (ECs) and smooth muscle cells (SMCs), where it modulates mitochondrial activity, Ca2+ homeostasis, cardiomyocytes electrical activity and contractility, cardiac embryonic development and fibroblast proliferation, as well as vascular permeability, dilatation and constriction. On the other hand, TRPV4 channels participate in several cardiac pathological processes such as the development of cardiac fibrosis, hypertrophy, ischemia-reperfusion injuries, heart failure, myocardial infarction and arrhythmia. In this manuscript, we provide an overview of TRPV4 channel implications in cardiac physiology and discuss the potential of the TRPV4 channel as a therapeutic target against cardiovascular diseases.
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Affiliation(s)
- Sébastien Chaigne
- IHU LIRYC Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, 33600 Bordeaux, France
- Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM U1045, University of Bordeaux, 33600 Pessac, France
- Electrophysiology and Ablation Unit, Bordeaux University Hospital, 33604 Pessac, France
| | - Solène Barbeau
- Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM U1045, University of Bordeaux, 33600 Pessac, France
| | - Thomas Ducret
- Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM U1045, University of Bordeaux, 33600 Pessac, France
| | - Romain Guinamard
- UR4650, Physiopathologie et Stratégies d'Imagerie du Remodelage Cardiovasculaire, GIP Cyceron, Université de Caen Normandie, 14032 Caen, France
| | - David Benoist
- IHU LIRYC Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, 33600 Bordeaux, France
- Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM U1045, University of Bordeaux, 33600 Pessac, France
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30
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Wu X, Cunningham KP, Ramentol R, Perez ME, Larsson HP. Similar voltage-sensor movement in spHCN channels can cause closing, opening, or inactivation. J Gen Physiol 2023; 155:e202213170. [PMID: 36752823 PMCID: PMC9948645 DOI: 10.1085/jgp.202213170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 11/22/2022] [Accepted: 01/27/2023] [Indexed: 02/09/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels contribute to the rhythmic firing of pacemaker neurons and cardiomyocytes. Mutations in HCN channels are associated with cardiac arrhythmia and epilepsy. HCN channels belong to the superfamily of voltage-gated K+ channels, most of which are activated by depolarization. HCN channels, however, are activated by hyperpolarization. The mechanism behind this reversed gating polarity of HCN channels is not clear. We here show that sea urchin HCN (spHCN) channels with mutations in the C-terminal part of the voltage sensor use the same voltage-sensor movement to either close or open in response to hyperpolarizations depending on the absence or presence of cAMP. Our results support that non-covalent interactions at the C-terminal end of the voltage sensor are critical for HCN gating polarity. These interactions are also critical for the proper closing of the channels because these mutations exhibit large constitutive currents. Since a similar voltage-sensor movement can cause both depolarization- and hyperpolarization-activation in the same channel, this suggests that the coupling between the voltage sensor and the pore is changed to create channels opened by different polarities. We also show an identical voltage-sensor movement in activated and inactivated spHCN channels and suggest a model for spHCN activation and inactivation. Our results suggest the possibility that channels open by opposite voltage dependence, such as HCN and the related EAG channels, use the same voltage-sensor movement but different coupling mechanisms between the voltage sensor and the gate.
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Affiliation(s)
- Xiaoan Wu
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Kevin P. Cunningham
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Rosamary Ramentol
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Marta E. Perez
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - H. Peter Larsson
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
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31
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Tipper E, Leitão N, Dangeville P, Lawson DM, Charpentier M. A novel mutant allele of AtCNGC15 reveals a dual function of nuclear calcium release in the root meristem. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:2572-2584. [PMID: 36715622 PMCID: PMC10112680 DOI: 10.1093/jxb/erad041] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 01/27/2023] [Indexed: 06/06/2023]
Abstract
Calcium release to the nucleoplasm of root meristem cells was demonstrated to modulate root development. The calcium channel encoded by cyclic nucleotide-gated channel (CNGC) 15 localizes at the nuclear envelope in young Arabidopsis seedlings. In contrast, at later stages of root growth, overexpression analysis showed that AtCNGC15 can relocalize to the plasma membrane to mediate primary nitrate-induced gene expression. This raises the question as to whether nuclear localized AtCNGC15 is required for root apical meristem development in young Arabidopsis seedlings, and whether nitrate signalling occurs independently of nuclear localized AtCNGC15 at this developmental stage. In this study, we characterize a novel mutant allele of AtCNGC15 and demonstrate that the mutation of a highly conserved aspartic acid in the C-linker domain is sufficient to impair the gating of AtCNCG15. We demonstrate that AtCNGC15 mediates the nuclear calcium release that modulates root apical meristem development and nitrate-induced LBD39 expression. We also show that, in the presence of nitrate, the relocalization of AtCNGC15 at the plasma membrane occurs specifically in the columella cells. Our results further suggest that the induction of LBD37, LBD38, and LBD39 in the presence of nitrate is modulated by different inputs of cytoplasmic or nuclear calcium release.
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Affiliation(s)
- Emily Tipper
- Department of Cell and Developmental Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | | | - Pierre Dangeville
- Department of Cell and Developmental Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | - David M Lawson
- Department of Biological Chemistry, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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32
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Zhang M, Shan Y, Pei D. Mechanism underlying delayed rectifying in human voltage-mediated activation Eag2 channel. Nat Commun 2023; 14:1470. [PMID: 36928654 PMCID: PMC10020445 DOI: 10.1038/s41467-023-37204-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 03/07/2023] [Indexed: 03/18/2023] Open
Abstract
The transmembrane voltage gradient is a general physico-chemical cue that regulates diverse biological function through voltage-gated ion channels. How voltage sensing mediates ion flows remains unknown at the molecular level. Here, we report six conformations of the human Eag2 (hEag2) ranging from closed, pre-open, open, and pore dilation but non-conducting states captured by cryo-electron microscopy (cryo-EM). These multiple states illuminate dynamics of the selectivity filter and ion permeation pathway with delayed rectifier properties and Cole-Moore effect at the atomic level. Mechanistically, a short S4-S5 linker is coupled with the constrict sites to mediate voltage transducing in a non-domain-swapped configuration, resulting transitions for constrict sites of F464 and Q472 from gating to open state stabilizing for voltage energy transduction. Meanwhile, an additional potassium ion occupied at positions S6 confers the delayed rectifier property and Cole-Moore effects. These results provide insight into voltage transducing and potassium current across membrane, and shed light on the long-sought Cole-Moore effects.
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Affiliation(s)
- Mingfeng Zhang
- Fudan University, 200433, Shanghai, China
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, 310000, Hangzhou, China
| | - Yuanyue Shan
- Fudan University, 200433, Shanghai, China
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, 310000, Hangzhou, China
| | - Duanqing Pei
- Laboratory of Cell Fate Control, School of Life Sciences, Westlake University, 310000, Hangzhou, China.
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33
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Lara A, Simonson BT, Ryan JF, Jegla T. Genome-Scale Analysis Reveals Extensive Diversification of Voltage-Gated K+ Channels in Stem Cnidarians. Genome Biol Evol 2023; 15:6994550. [PMID: 36669828 PMCID: PMC9989356 DOI: 10.1093/gbe/evad009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/04/2023] [Accepted: 01/16/2023] [Indexed: 01/22/2023] Open
Abstract
Ion channels are highly diverse in the cnidarian model organism Nematostella vectensis (Anthozoa), but little is known about the evolutionary origins of this channel diversity and its conservation across Cnidaria. Here, we examined the evolution of voltage-gated K+ channels in Cnidaria by comparing genomes and transcriptomes of diverse cnidarian species from Anthozoa and Medusozoa. We found an average of over 40 voltage-gated K+ channel genes per species, and a phylogenetic reconstruction of the Kv, KCNQ, and Ether-a-go-go (EAG) gene families identified 28 voltage-gated K+ channels present in the last common ancestor of Anthozoa and Medusozoa (23 Kv, 1 KCNQ, and 4 EAG). Thus, much of the diversification of these channels took place in the stem cnidarian lineage prior to the emergence of modern cnidarian classes. In contrast, the stem bilaterian lineage, from which humans evolved, contained no more than nine voltage-gated K+ channels. These results hint at a complexity to electrical signaling in all cnidarians that contrasts with the perceived anatomical simplicity of their neuromuscular systems. These data provide a foundation from which the function of these cnidarian channels can be investigated, which will undoubtedly provide important insights into cnidarian physiology.
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Affiliation(s)
- Adolfo Lara
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, Florida, USA
| | - Benjamin T Simonson
- Department of Biology and Huck Institutes for the Life Sciences, Penn State University, University Park, Pennsylvania, USA
| | - Joseph F Ryan
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, Florida, USA.,Department of Biology, University of Florida, Gainesville, Florida, USA
| | - Timothy Jegla
- Department of Biology and Huck Institutes for the Life Sciences, Penn State University, University Park, Pennsylvania, USA
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34
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Bassetto CAZ, Costa F, Guardiani C, Bezanilla F, Giacomello A. Noncanonical electromechanical coupling paths in cardiac hERG potassium channel. Nat Commun 2023; 14:1110. [PMID: 36849440 PMCID: PMC9971164 DOI: 10.1038/s41467-023-36730-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 02/15/2023] [Indexed: 03/01/2023] Open
Abstract
Voltage-gated potassium channels are involved in many physiological processes such as nerve impulse transmission, the heartbeat, and muscle contraction. However, for many of them the molecular determinants of the gating mechanism remain elusive. Here, using a combination of theoretical and experimental approaches, we address this problem focusing on the cardiac hERG potassium channel. Network analysis of molecular dynamics trajectories reveals the presence of a kinematic chain of residues that couples the voltage sensor domain to the pore domain and involves the S4/S1 and S1/S5 subunit interfaces. Mutagenesis experiments confirm the role of these residues and interfaces in the activation and inactivation mechanisms. Our findings demonstrate the presence of an electromechanical transduction path crucial for the non-domain-swapped hERG channel gating that resembles the noncanonical path identified in domain-swapped K+ channels.
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Affiliation(s)
- Carlos A Z Bassetto
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Flavio Costa
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Rome, Italy
| | - Carlo Guardiani
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Rome, Italy
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
- Centro Interdisciplinario de Neurociencias, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso, Chile.
| | - Alberto Giacomello
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Rome, Italy.
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Abstract
Polycystin subunits can form hetero- and homotetrameric ion channels in the membranes of various compartments of the cell. Homotetrameric polycystin channels are voltage- and calcium-modulated, whereas heterotetrameric versions are proposed to be ligand- or autoproteolytically regulated. Their importance is underscored by variants associated with autosomal dominant polycystic kidney disease and by vital roles in fertilization and embryonic development. The diversity in polycystin assembly and subcellular distribution allows for a multitude of sensory functions by this class of channels. In this review, we highlight their recent structural and functional characterization, which has provided a molecular blueprint to investigate the conformational changes required for channel opening in response to unique stimuli. We consider each polycystin channel type individually, discussing how they contribute to sensory cell biology, as well as their impact on the physiology of various tissues.
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Affiliation(s)
- Orhi Esarte Palomero
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA;
| | - Megan Larmore
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA;
| | - Paul G DeCaen
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA;
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Hsieh CH, Chou CC, Fang YC, Hsu PH, Chiu YH, Yang CS, Jow GM, Tang CY, Jeng CJ. 14-3-3 proteins regulate cullin 7-mediated Eag1 degradation. Cell Biosci 2023; 13:18. [PMID: 36717938 PMCID: PMC9885684 DOI: 10.1186/s13578-023-00969-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Mutations in the human gene encoding the neuron-specific Eag1 (KV10.1; KCNH1) potassium channel are linked to congenital neurodevelopmental diseases. Disease-causing mutant Eag1 channels manifest aberrant gating function and defective protein homeostasis. Both the E3 ubiquitin ligase cullin 7 (Cul7) and the small acid protein 14-3-3 serve as binding partners of Eag1. Cul7 mediates proteasomal and lysosomal degradation of Eag1 protein, whereas over-expression of 14-3-3 notably reduces Eag1 channel activity. It remains unclear whether 14-3-3 may also contribute to Eag1 protein homeostasis. RESULTS In human cell line and native rat neurons, disruptions of endogenous 14-3-3 function with the peptide inhibitor difopein or specific RNA interference up-regulated Eag1 protein level in a transcription-independent manner. Difopein hindered Eag1 protein ubiquitination at the endoplasmic reticulum and the plasma membrane, effectively promoting the stability of both immature and mature Eag1 proteins. Suppression of endogenous 14-3-3 function also reduced excitotoxicity-associated Eag1 degradation in neurons. Difopein diminished Cul7-mediated Eag1 degradation, and Cul7 knock-down abolished the effect of difopein on Eag1. Inhibition of endogenous 14-3-3 function substantially perturbed the interaction of Eag1 with Cul7. Further structural analyses suggested that the intracellular Per-Arnt-Sim (PAS) domain and cyclic nucleotide-binding homology domain (CNBHD) of Eag1 are essential for the regulatory effect of 14-3-3 proteins. Significantly, suppression of endogenous 14-3-3 function reduced Cul7-mediated degradation of disease-associated Eag1 mutant proteins. CONCLUSION Overall these results highlight a chaperone-like role of endogenous 14-3-3 proteins in regulating Eag1 protein homeostasis, as well as a therapeutic potential of 14-3-3 modulators in correcting defective protein expression of disease-causing Eag1 mutants.
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Affiliation(s)
- Chang-Heng Hsieh
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chia-Cheng Chou
- grid.36020.370000 0000 8889 3720National Laboratory Animal Center, National Applied Research Laboratories, Taipei, Taiwan
| | - Ya-Ching Fang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Po-Hao Hsu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Yi-Hung Chiu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chi-Sheng Yang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Guey-Mei Jow
- grid.256105.50000 0004 1937 1063School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan
| | - Chih-Yung Tang
- grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Chung-Jiuan Jeng
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.260539.b0000 0001 2059 7017Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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37
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Zangerl-Plessl EM, Wu W, Sanguinetti MC, Stary-Weinzinger A. Binding of RPR260243 at the intracellular side of the hERG1 channel pore domain slows closure of the helix bundle crossing gate. Front Mol Biosci 2023; 10:1137368. [PMID: 36911523 PMCID: PMC9996038 DOI: 10.3389/fmolb.2023.1137368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 02/07/2023] [Indexed: 02/25/2023] Open
Abstract
The opening and closing of voltage-dependent potassium channels is dependent on a tight coupling between movement of the voltage sensing S4 segments and the activation gate. A specific interaction between intracellular amino- and carboxyl-termini is required for the characteristically slow rate of channel closure (deactivation) of hERG1 channels. Compounds that increase hERG1 channel currents represent a novel approach for prevention of arrhythmia associated with prolonged ventricular repolarization. RPR260243 (RPR), a quinoline oxo-propyl piperidine derivative, inhibits inactivation and dramatically slows the rate of hERG1 channel deactivation. Here we report that similar to its effect on wild-type channels, RPR greatly slows the deactivation rate of hERG1 channels missing their amino-termini, or of split channels lacking a covalent link between the voltage sensor domain and the pore domain. By contrast, RPR did not slow deactivation of C-terminal truncated hERG1 channels or D540K hERG1 mutant channels activated by hyperpolarization. Together, these findings indicate that ability of RPR to slow deactivation requires an intact C-terminus, does not slow deactivation by stabilizing an interaction involving the amino-terminus or require a covalent link between the voltage sensor and pore domains. All-atom molecular dynamics simulations using the cryo-EM structure of the hERG1 channel revealed that RPR binds to a pocket located at the intracellular ends of helices S5 and S6 of a single subunit. The slowing of channel deactivation by RPR may be mediated by disruption of normal S5-S6 interactions.
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Affiliation(s)
| | - Wei Wu
- Department of Internal Medicine, Nora Eccles Harrison Cardiovascular Research & Training Institute, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT, United States
| | - Michael C Sanguinetti
- 3 Department of Internal Medicine, Division of Cardiovascular Medicine, Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt LakeCity, UT, United States
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38
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Kudaibergenova M, Guo J, Khan HM, Lees-Miller J, Mousaei M, Miranda W, Ngo VA, Noskov SY, Tieleman DP, Duff HJ. The voltage-sensing domain of a hERG1 mutant is a cation-selective channel. Biophys J 2022; 121:4585-4599. [PMID: 36815709 PMCID: PMC9748372 DOI: 10.1016/j.bpj.2022.10.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/29/2022] [Accepted: 10/24/2022] [Indexed: 11/24/2022] Open
Abstract
A cationic leak current known as an "omega current" may arise from mutations of the first charged residue in the S4 of the voltage sensor domains of sodium and potassium voltage-gated channels. The voltage-sensing domains (VSDs) in these mutated channels act as pores allowing nonspecific passage of cations, such as Li+, K+, Cs+, and guanidinium. Interestingly, no omega currents have been previously detected in the nonswapped voltage-gated potassium channels such as the human-ether-a-go-go-related (hERG1), hyperpolarization-activated cyclic nucleotide-gated, and ether-a-go-go channels. In this work, we discovered a novel omega current by mutating the first charged residue of the S4 of the hERG1, K525 to serine. To characterize this omega current, we used various probes, including the hERG1 pore domain blocker, dofetilide, to show that the omega current does not require cation flux via the canonical pore domain. In addition, the omega flux does not cross the conventional selectivity filter. We also show that the mutated channel (K525S hERG1) conducts guanidinium. These data are indicative of the formation of an omega current channel within the VSD. Using molecular dynamics simulations with replica-exchange umbrella sampling simulations of the wild-type hERG1 and the K525S hERG1, we explored the molecular underpinnings governing the cation flow in the VSD of the mutant. We also show that the wild-type hERG1 may form water crevices supported by the biophysical surface accessibility data. Overall, our multidisciplinary study demonstrates that the VSD of hERG1 may act as a cation-selective channel wherein a mutation of the first charged residue in the S4 generates an omega current. Our simulation uncovers the atomistic underpinning of this mechanism.
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Affiliation(s)
- Meruyert Kudaibergenova
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Jiqing Guo
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Hanif M Khan
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - James Lees-Miller
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Mahdi Mousaei
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Williams Miranda
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Van A Ngo
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Sergei Yu Noskov
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada.
| | - Henry J Duff
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada.
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39
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Abstract
Voltage-dependent ion channels regulate the opening of their pores by sensing the membrane voltage. This process underlies the propagation of action potentials and other forms of electrical activity in cells. The voltage dependence of these channels is governed by the transmembrane displacement of the positive charged S4 helix within their voltage-sensor domains. We use cryo-electron microscopy to visualize this movement in the mammalian Eag voltage-dependent potassium channel in lipid membrane vesicles with a voltage difference across the membrane. Multiple structural configurations show that the applied electric field displaces S4 toward the cytoplasm by two helical turns, resulting in an extended interfacial helix near the inner membrane leaflet. The position of S4 in this down conformation is sterically incompatible with an open pore, thus explaining how movement of the voltage sensor at hyperpolarizing membrane voltages locks the pore shut in this kind of voltage-dependent K+ (Kv) channel. The structures solved in lipid bilayer vesicles detail the intricate interplay between Kv channels and membranes, from showing how arginines are stabilized deep within the membrane and near phospholipid headgroups, to demonstrating how the channel reshapes the inner leaflet of the membrane itself.
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40
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Dickinson MS, Pourmal S, Gupta M, Bi M, Stroud RM. Symmetry Reduction in a Hyperpolarization-Activated Homotetrameric Ion Channel. Biochemistry 2022; 61:2177-2181. [PMID: 34964607 PMCID: PMC9931035 DOI: 10.1021/acs.biochem.1c00654] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Plants obtain nutrients from the soil via transmembrane transporters and channels in their root hairs, from which ions radially transport in toward the xylem for distribution across the plant body. We determined structures of the hyperpolarization-activated channel AKT1 from Arabidopsis thaliana, which mediates K+ uptake from the soil into plant roots. These structures of AtAKT1 embedded in lipid nanodiscs show that the channel undergoes a reduction of C4 to C2 symmetry, possibly to regulate its electrical activation.
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Affiliation(s)
- Miles Sasha Dickinson
- Department of Biochemistry and Biophysics, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94158, United States
- Chemistry and Chemical Biology Graduate Program, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94143, United States
| | - Sergei Pourmal
- Department of Biochemistry and Biophysics, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94158, United States
- Chemistry and Chemical Biology Graduate Program, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94143, United States
| | - Meghna Gupta
- Department of Biochemistry and Biophysics, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94158, United States
| | - Maxine Bi
- Department of Biochemistry and Biophysics, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94158, United States
- Graduate Group in Biophysics, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94143, United States
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94158, United States
- Chemistry and Chemical Biology Graduate Program, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94143, United States
- Graduate Group in Biophysics, University of California San Francisco, Genentech Hall, 600 16th Street, San Francisco, California 94143, United States
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41
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New Diarylamine K V10.1 Inhibitors and Their Anticancer Potential. Pharmaceutics 2022; 14:pharmaceutics14091963. [PMID: 36145712 PMCID: PMC9501377 DOI: 10.3390/pharmaceutics14091963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 11/17/2022] Open
Abstract
Expression of the voltage-gated potassium channel KV10.1 (Eag1) has been detected in over 70% of human cancers, making the channel a promising new target for new anticancer drug discovery. A new structural class of KV10.1 inhibitors was prepared by structural optimisation and exploration of the structure–activity relationship of the previously published hit compound ZVS-08 (1) and its optimised analogue 2. The potency and selectivity of the new inhibitors between KV10.1 and hERG were investigated using whole-cell patch-clamp experiments. We obtained two new optimised KV10.1 inhibitors, 17a and 18b, with improved nanomolar IC50 values of 568 nM and 214 nM, respectively. Compound 17a exhibited better ratio between IC50 values for hEAG1 and hERG than previously published diarylamine inhibitors. Compounds 17a and 18b moderately inhibited the growth of the KV10.1-expressing cell line MCF-7 in two independent assays. In addition, 17a and 18b also inhibited the growth of hERG-expressing Panc-1 cells with higher potency compared with MCF-7 cells. The main obstacle for newly developed diarylamine KV10.1 inhibitors remains the selectivity toward the hERG channel, which needs to be addressed with targeted drug design strategies in the future.
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42
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TTYH family members form tetrameric complexes at the cell membrane. Commun Biol 2022; 5:886. [PMID: 36042377 PMCID: PMC9427776 DOI: 10.1038/s42003-022-03862-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Accepted: 08/18/2022] [Indexed: 11/08/2022] Open
Abstract
The conserved Tweety homolog (TTYH) family consists of three paralogs in vertebrates, displaying a ubiquitous expression pattern. Although considered as ion channels for almost two decades, recent structural and functional analyses refuted this role. Intriguingly, while all paralogs shared a dimeric stoichiometry following detergent solubilization, their structures revealed divergence in their relative subunit orientation. Here, we determined the stoichiometry of intact mouse TTYH (mTTYH) complexes in cells. Using cross-linking and single-molecule fluorescence microscopy, we demonstrate that mTTYH1 and mTTYH3 form tetramers at the plasma membrane, stabilized by interactions between their extracellular domains. Using blue-native PAGE, fluorescence-detection size-exclusion chromatography, and hydrogen/deuterium exchange mass spectrometry (HDX-MS), we reveal that detergent solubilization results in tetramers destabilization, leading to their dissolution into dimers. Moreover, HDX-MS demonstrates that the extracellular domains are stabilized in the context of the tetrameric mTTYH complex. Together, our results expose the innate tetrameric organization of TTYH complexes at the cell membrane. Future structural analyses of these assemblies in native membranes are required to illuminate their long-sought cellular function.
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43
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Intracellular hemin is a potent inhibitor of the voltage-gated potassium channel Kv10.1. Sci Rep 2022; 12:14645. [PMID: 36030326 PMCID: PMC9420133 DOI: 10.1038/s41598-022-18975-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/23/2022] [Indexed: 11/08/2022] Open
Abstract
Heme, an iron-protoporphyrin IX complex, is a cofactor bound to various hemoproteins and supports a broad range of functions, such as electron transfer, oxygen transport, signal transduction, and drug metabolism. In recent years, there has been a growing recognition of heme as a non-genomic modulator of ion channel functions. Here, we show that intracellular free heme and hemin modulate human ether à go-go (hEAG1, Kv10.1) voltage-gated potassium channels. Application of hemin to the intracellular side potently inhibits Kv10.1 channels with an IC50 of about 4 nM under ambient and 63 nM under reducing conditions in a weakly voltage-dependent manner, favoring inhibition at resting potential. Functional studies on channel mutants and biochemical analysis of synthetic and recombinant channel fragments identified a heme-binding motif CxHx8H in the C-linker region of the Kv10.1 C terminus, with cysteine 541 and histidines 543 and 552 being important for hemin binding. Binding of hemin to the C linker may induce a conformational constraint that interferes with channel gating. Our results demonstrate that heme and hemin are endogenous modulators of Kv10.1 channels and could be exploited to modulate Kv10.1-mediated cellular functions.
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44
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Luis E, Anaya-Hernández A, León-Sánchez P, Durán-Pastén ML. The Kv10.1 Channel: A Promising Target in Cancer. Int J Mol Sci 2022; 23:ijms23158458. [PMID: 35955591 PMCID: PMC9369319 DOI: 10.3390/ijms23158458] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/25/2022] [Accepted: 07/27/2022] [Indexed: 12/19/2022] Open
Abstract
Carcinogenesis is a multistage process involving the dysregulation of multiple genes, proteins, and pathways that make any normal cell acquire a cancer cell phenotype. Therefore, it is no surprise that numerous ion channels could be involved in this process. Since their discovery and subsequent cloning, ion channels have been established as therapeutic targets in excitable cell pathologies (e.g., cardiac arrhythmias or epilepsy); however, their involvement in non-excitable cell pathologies is relatively recent. Among all ion channels, the voltage-gated potassium channels Kv10.1 have been established as a promising target in cancer treatment due to their high expression in tumoral tissues compared to low levels in healthy tissues.
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Affiliation(s)
- Enoch Luis
- Cátedras CONACYT—Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico; (P.L.-S.); (M.L.D.-P.)
- Correspondence:
| | - Arely Anaya-Hernández
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Km. 10.5 Autopista Tlaxcala-San Martín, Tlaxcala 90120, Mexico;
| | - Paulina León-Sánchez
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico; (P.L.-S.); (M.L.D.-P.)
| | - María Luisa Durán-Pastén
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico; (P.L.-S.); (M.L.D.-P.)
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Ong ST, Tyagi A, Chandy KG, Bhushan S. Mechanisms Underlying C-type Inactivation in Kv Channels: Lessons From Structures of Human Kv1.3 and Fly Shaker-IR Channels. Front Pharmacol 2022; 13:924289. [PMID: 35833027 PMCID: PMC9271579 DOI: 10.3389/fphar.2022.924289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/06/2022] [Indexed: 11/13/2022] Open
Abstract
Voltage-gated potassium (Kv) channels modulate the function of electrically-excitable and non-excitable cells by using several types of “gates” to regulate ion flow through the channels. An important gating mechanism, C-type inactivation, limits ion flow by transitioning Kv channels into a non-conducting inactivated state. Here, we highlight two recent papers, one on the human Kv1.3 channel and the second on the Drosophila Shaker Kv channel, that combined cryogenic electron microscopy and molecular dynamics simulation to define mechanisms underlying C-type inactivation. In both channels, the transition to the non-conducting inactivated conformation begins with the rupture of an intra-subunit hydrogen bond that fastens the selectivity filter to the pore helix. The freed filter swings outwards and gets tethered to an external residue. As a result, the extracellular end of the selectivity filter dilates and K+ permeation through the pore is impaired. Recovery from inactivation may entail a reversal of this process. Such a reversal, at least partially, is induced by the peptide dalazatide. Binding of dalazatide to external residues in Kv1.3 frees the filter to swing inwards. The extracellular end of the selectivity filter narrows allowing K+ to move in single file through the pore typical of conventional knock-on conduction. Inter-subunit hydrogen bonds that stabilize the outer pore in the dalazatide-bound structure are equivalent to those in open-conducting conformations of Kv channels. However, the intra-subunit bond that fastens the filter to the pore-helix is absent, suggesting an incomplete reversal of the process. These mechanisms define how Kv channels self-regulate the flow of K+ by changing the conformation of the selectivity filter.
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Affiliation(s)
- Seow Theng Ong
- LKCMedicine-ICESing Ion Channel Platform, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Anu Tyagi
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Singapore and Nanyang Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore
| | - K. George Chandy
- LKCMedicine-ICESing Ion Channel Platform, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
- *Correspondence: K. George Chandy, ; Shashi Bhushan,
| | - Shashi Bhushan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- Singapore and Nanyang Institute of Structural Biology, Nanyang Technological University, Singapore, Singapore
- *Correspondence: K. George Chandy, ; Shashi Bhushan,
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Abstract
In neurosecretion, allosteric communication between voltage sensors and Ca2+ binding in BK channels is crucially involved in damping excitatory stimuli. Nevertheless, the voltage-sensing mechanism of BK channels is still under debate. Here, based on gating current measurements, we demonstrate that two arginines in the transmembrane segment S4 (R210 and R213) function as the BK gating charges. Significantly, the energy landscape of the gating particles is electrostatically tuned by a network of salt bridges contained in the voltage sensor domain (VSD). Molecular dynamics simulations and proton transport experiments in the hyperpolarization-activated R210H mutant suggest that the electric field drops off within a narrow septum whose boundaries are defined by the gating charges. Unlike Kv channels, the charge movement in BK appears to be limited to a small displacement of the guanidinium moieties of R210 and R213, without significant movement of the S4.
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Del Vecchio G, Galindo-Sánchez CE, Tripp-Valdez MA, López-Landavery EA, Rosas C, Mascaró M. Transcriptomic response in thermally challenged seahorses Hippocampus erectus: The effect of magnitude and rate of temperature change. Comp Biochem Physiol B Biochem Mol Biol 2022; 262:110771. [PMID: 35691555 DOI: 10.1016/j.cbpb.2022.110771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 05/17/2022] [Accepted: 06/06/2022] [Indexed: 10/18/2022]
Abstract
Hippocampus erectus inhabiting the shallow coastal waters of the southern Gulf of Mexico are naturally exposed to marked temperature variations occurring in different temporal scales. Under such heterogeneous conditions, a series of physiological and biochemical adjustments take place to restore and maintain homeostasis. This study investigated the molecular mechanisms involved in the response of H. erectus to increased temperature using transcriptome analysis based on RNA-Seq technology. Data was obtained from seahorses after 0.5-h exposure to combinations of different target temperatures (26 °C: control, and increased to 30 and 33 °C) and rates of thermal increase (abrupt: < 5 min; gradual: 1-1.5 °C every 3 h). The transcriptome of seahorses was assembled de novo using Trinity software to obtain 29,211 genes and 30,479 transcripts comprising 27,520,965 assembled bases. Seahorse exposure to both 30 and 33 °C triggered characteristic processes of the cellular stress response, regardless of the rate of thermal change. The transcriptomic profiles of H. erectus suggest an arrest of muscle development processes, the activation of heat shock proteins, and a switch to anaerobic metabolism within the first 0.5 h of exposure to target temperatures to ensure energy supply. Interestingly, apoptotic processes involving caspase were activated principally in gradual treatments, suggesting that prolonged exposure to even sublethal temperatures results in the accumulation of deleterious effects that may eventually terminate in cellular death. Results herein validate 30 °C and 33 °C as potential upper limits of thermal tolerance for H. erectus at the southernmost boundary of its geographic distribution.
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Affiliation(s)
- G Del Vecchio
- Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - C E Galindo-Sánchez
- Departamento de Biotecnología Marina, Laboratorio de Genómica Funcional, CICESE, Ensenada, Baja California, Mexico. https://twitter.com/ClaraGalindo3
| | - M A Tripp-Valdez
- Departamento de Biotecnología Marina, Laboratorio de Genómica Funcional, CICESE, Ensenada, Baja California, Mexico. https://twitter.com/MiguelTripp
| | - E A López-Landavery
- Departamento de Biotecnología Marina, Laboratorio de Genómica Funcional, CICESE, Ensenada, Baja California, Mexico. https://twitter.com/EdgarLo30205255
| | - C Rosas
- Unidad Multidisciplinaria de Docencia e Investigación-Sisal, Facultad de Ciencias, Universidad Nacional Autónoma de México, Sisal, Yucatán, Mexico. https://twitter.com/DrCarlosRosasV
| | - M Mascaró
- Unidad Multidisciplinaria de Docencia e Investigación-Sisal, Facultad de Ciencias, Universidad Nacional Autónoma de México, Sisal, Yucatán, Mexico.
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Yelshanskaya MV, Sobolevsky AI. Ligand-Binding Sites in Vanilloid-Subtype TRP Channels. Front Pharmacol 2022; 13:900623. [PMID: 35652046 PMCID: PMC9149226 DOI: 10.3389/fphar.2022.900623] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 04/06/2022] [Indexed: 02/02/2023] Open
Abstract
Vanilloid-subfamily TRP channels TRPV1-6 play important roles in various physiological processes and are implicated in numerous human diseases. Advances in structural biology, particularly the "resolution revolution" in cryo-EM, have led to breakthroughs in molecular characterization of TRPV channels. Structures with continuously improving resolution uncover atomic details of TRPV channel interactions with small molecules and protein-binding partners. Here, we provide a classification of structurally characterized binding sites in TRPV channels and discuss the progress that has been made by structural biology combined with mutagenesis, functional recordings, and molecular dynamics simulations toward understanding of the molecular mechanisms of ligand action. Given the similarity in structural architecture of TRP channels, 16 unique sites identified in TRPV channels may be shared between TRP channel subfamilies, although the chemical identity of a particular ligand will likely depend on the local amino-acid composition. The characterized binding sites and molecular mechanisms of ligand action create a diversity of druggable targets to aid in the design of new molecules for tuning TRP channel function in disease conditions.
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Affiliation(s)
| | - Alexander I. Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, United States
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Ye W, Zhao H, Dai Y, Wang Y, Lo YH, Jan LY, Lee CH. Activation and closed-state inactivation mechanisms of the human voltage-gated K V4 channel complexes. Mol Cell 2022; 82:2427-2442.e4. [PMID: 35597238 DOI: 10.1016/j.molcel.2022.04.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/03/2022] [Accepted: 04/24/2022] [Indexed: 12/30/2022]
Abstract
The voltage-gated ion channel activity depends on both activation (transition from the resting state to the open state) and inactivation. Inactivation is a self-restraint mechanism to limit ion conduction and is as crucial to membrane excitability as activation. Inactivation can occur when the channel is open or closed. Although open-state inactivation is well understood, the molecular basis of closed-state inactivation has remained elusive. We report cryo-EM structures of human KV4.2 channel complexes in inactivated, open, and closed states. Closed-state inactivation of KV4 involves an unprecedented symmetry breakdown for pore closure by only two of the four S4-S5 linkers, distinct from known mechanisms of open-state inactivation. We further capture KV4 in a putative resting state, revealing how voltage sensor movements control the pore. Moreover, our structures provide insights regarding channel modulation by KChIP2 and DPP6 auxiliary subunits. Our findings elucidate mechanisms of closed-state inactivation and voltage-dependent activation of the KV4 channel.
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Affiliation(s)
- Wenlei Ye
- Department of Physiology, University of California, San Francisco, CA 94158, USA
| | - Hongtu Zhao
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yaxin Dai
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yingdi Wang
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Yu-Hua Lo
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Lily Yeh Jan
- Department of Physiology, University of California, San Francisco, CA 94158, USA; Howard Hughes Medical Institute, University of California, San Francisco, CA 94158, USA.
| | - Chia-Hsueh Lee
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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50
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Sanchez-Conde FG, Jimenez-Vazquez EN, Auerbach DS, Jones DK. The ERG1 K+ Channel and Its Role in Neuronal Health and Disease. Front Mol Neurosci 2022; 15:890368. [PMID: 35600076 PMCID: PMC9113952 DOI: 10.3389/fnmol.2022.890368] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022] Open
Abstract
The ERG1 potassium channel, encoded by KCNH2, has long been associated with cardiac electrical excitability. Yet, a growing body of work suggests that ERG1 mediates physiology throughout the human body, including the brain. ERG1 is a regulator of neuronal excitability, ERG1 variants are associated with neuronal diseases (e.g., epilepsy and schizophrenia), and ERG1 serves as a potential therapeutic target for neuronal pathophysiology. This review summarizes the current state-of-the-field regarding the ERG1 channel structure and function, ERG1’s relationship to the mammalian brain and highlights key questions that have yet to be answered.
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Affiliation(s)
| | - Eric N. Jimenez-Vazquez
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - David S. Auerbach
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, United States
- *Correspondence: David S. Auerbach,
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
- David K. Jones,
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