1
|
Neelsen LC, Riel EB, Rinné S, Schmid FR, Jürs BC, Bedoya M, Langer JP, Eymsh B, Kiper AK, Cordeiro S, Decher N, Baukrowitz T, Schewe M. Ion occupancy of the selectivity filter controls opening of a cytoplasmic gate in the K 2P channel TALK-2. Nat Commun 2024; 15:7545. [PMID: 39215031 PMCID: PMC11364775 DOI: 10.1038/s41467-024-51812-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 08/16/2024] [Indexed: 09/04/2024] Open
Abstract
Two-pore domain K+ (K2P) channel activity was previously thought to be controlled primarily via a selectivity filter (SF) gate. However, recent crystal structures of TASK-1 and TASK-2 revealed a lower gate at the cytoplasmic pore entrance. Here, we report functional evidence of such a lower gate in the K2P channel K2P17.1 (TALK-2, TASK-4). We identified compounds (drugs and lipids) and mutations that opened the lower gate allowing the fast modification of pore cysteine residues. Surprisingly, stimuli that directly target the SF gate (i.e., pHe., Rb+ permeation, membrane depolarization) also opened the cytoplasmic gate. Reciprocally, opening of the lower gate reduced the electric work to open the SF via voltage driven ion binding. Therefore, it appears that the SF is so rigidly locked into the TALK-2 protein structure that changes in ion occupancy can pry open a distant lower gate and, vice versa, opening of the lower gate concurrently promote SF gate opening. This concept might extent to other K+ channels that contain two gates (e.g., voltage-gated K+ channels) for which such a positive gate coupling has been suggested, but so far not directly demonstrated.
Collapse
Affiliation(s)
- Lea C Neelsen
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Elena B Riel
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Philipps-University of Marburg, Marburg, Germany
| | | | - Björn C Jürs
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
- MSH Medical School Hamburg, University of Applied Sciences and Medical University, Hamburg, Germany
| | - Mauricio Bedoya
- 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
| | - Jan P Langer
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Bisher Eymsh
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Philipps-University of Marburg, Marburg, Germany
| | - Sönke Cordeiro
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Philipps-University of Marburg, Marburg, Germany.
| | - Thomas Baukrowitz
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany.
| | - Marcus Schewe
- Institute of Physiology, Christian-Albrechts University of Kiel, Kiel, Germany.
| |
Collapse
|
2
|
Mendez-Otalvaro E, Kopec W, de Groot BL. Effect of two activators on the gating of a K 2P channel. Biophys J 2024:S0006-3495(24)00528-9. [PMID: 39161093 DOI: 10.1016/j.bpj.2024.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 06/27/2024] [Accepted: 08/09/2024] [Indexed: 08/21/2024] Open
Abstract
TWIK-related potassium channel 1 (TREK1), a two-pore-domain mammalian potassium (K+) channel, regulates the resting potential across cell membranes, presenting a promising therapeutic target for neuropathy treatment. The gating of this channel converges in the conformation of the narrowest part of the pore: the selectivity filter (SF). Various hypotheses explain TREK1 gating modulation, including the dynamics of loops connecting the SF with transmembrane helices and the stability of hydrogen bond (HB) networks adjacent to the SF. Recently, two small molecules (Q6F and Q5F) were reported as activators that affect TREK1 by increasing its open probability in single-channel current measurements. Here, using molecular dynamics simulations, we investigate the effect of these ligands on the previously proposed modulation mechanisms of TREK1 gating compared to the apo channel. Our findings reveal that loop dynamics at the upper region of the SF exhibit only a weak correlation with permeation events/nonpermeation periods, whereas the HB network behind the SF appears more correlated. These nonpermeation periods arise from both distinct mechanisms: a C-type inactivation (resulting from dilation at the top of the SF), which has been described previously, and a carbonyl flipping in an SF binding site. We find that, besides the prevention of C-type inactivation in the channel, the ligands increase the probability of permeation by modulating the dynamics of the carbonyl flipping, influenced by a threonine residue at the bottom of the SF. These results offer insights for rational ligand design to optimize the gating modulation of TREK1 and related K+ channels.
Collapse
Affiliation(s)
- Edward Mendez-Otalvaro
- Computational Biomolecular Dynamics Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Wojciech Kopec
- Computational Biomolecular Dynamics Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany; Department of Chemistry, Queen Mary University of London, London, United Kingdom.
| | - Bert L de Groot
- Computational Biomolecular Dynamics Group, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
| |
Collapse
|
3
|
Deal PE, Lee H, Mondal A, Lolicato M, Mendonça PRFD, Black H, Jang S, El-Hilali X, Bryant C, Isacoff EY, Renslo AR, Minor DL. Development of covalent chemogenetic K 2P channel activators. Cell Chem Biol 2024; 31:1305-1323.e9. [PMID: 39029456 DOI: 10.1016/j.chembiol.2024.06.006] [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: 11/01/2023] [Revised: 04/19/2024] [Accepted: 06/19/2024] [Indexed: 07/21/2024]
Abstract
K2P potassium channels regulate excitability by affecting cellular resting membrane potential in the brain, cardiovascular system, immune cells, and sensory organs. Despite their important roles in anesthesia, arrhythmia, pain, hypertension, sleep, and migraine, the ability to control K2P function remains limited. Here, we describe a chemogenetic strategy termed CATKLAMP (covalent activation of TREK family K+ channels to clamp membrane potential) that leverages the discovery of a K2P modulator pocket site that reacts with electrophile-bearing derivatives of a TREK subfamily small-molecule activator, ML335, to activate the channel irreversibly. We show that CATKLAMP can be used to probe fundamental aspects of K2P function, as a switch to silence neuronal firing, and is applicable to all TREK subfamily members. Together, our findings exemplify a means to alter K2P channel activity that should facilitate molecular and systems level studies of K2P function and enable the search for new K2P modulators.
Collapse
Affiliation(s)
- Parker E Deal
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA; Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 93858-2330, USA
| | - Haerim Lee
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA
| | - Abhisek Mondal
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA
| | - Marco Lolicato
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA
| | | | - Holly Black
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Seil Jang
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA
| | - Xochina El-Hilali
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 93858-2330, USA
| | - Clifford Bryant
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 93858-2330, USA
| | - Ehud Y Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Weill Neurohub, University of California, Berkeley, Berkeley, CA 94720, USA; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Adam R Renslo
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 93858-2330, USA.
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 93858-2330, USA; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA; Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 93858-2330, USA; California Institute for Quantitative Biomedical Research, University of California, San Francisco, San Francisco, CA 93858-2330, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA 93858-2330, USA.
| |
Collapse
|
4
|
Roy-Chowdhury S, Jang S, Abderemane-Ali F, Naughton F, Grabe M, Minor DL. Structure of the human K 2P13.1(THIK-1) channel reveals a novel hydrophilic pore restriction and lipid cofactor site. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.26.600491. [PMID: 38979306 PMCID: PMC11230452 DOI: 10.1101/2024.06.26.600491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The halothane-inhibited K2P leak potassium channel K2P13.1 (THIK-1)1-3 is found in diverse cells1,4 including neurons1,5 and microglia6-8 where it affects surveillance6, synaptic pruning7, phagocytosis7, and inflammasome-mediated interleukin-1β release6,8,9. As with many K2Ps1,5,10-14 and other voltage-gated ion channel (VGIC) superfamily members3,15,16, polyunsaturated fatty acid (PUFA) lipids modulate K2P13.1 (THIK-1)1,5,14,17 via a poorly understood mechanism. Here, we present cryo-electronmicroscopy (cryo-EM) structures of human K2P13.1 (THIK-1) and mutants in lipid nanodiscs and detergent. These reveal that, unlike other K2Ps13,18-24, K2P13.1 (THIK-1) has a two-chamber aqueous inner cavity obstructed by a M4 transmembrane helix tyrosine (Tyr273, the flow restrictor). This hydrophilic barrier can be opened by an activatory mutation, S136P25, at natural break in the M2 transmembrane helix and by intrinsic channel dynamics. The structures also reveal a buried lipid in the P1/M4 intersubunit interface at a location, the PUFA site, that coincides with the TREK subfamily K2P modulator pocket for small molecule agonists18,26,27. This overlap, together with the effects of mutation on K2P13.1 (THIK-1) PUFA responses, indicates that the PUFA site lipids are K2P13.1 (THIK-1) cofactors. Comparison with the PUFA-responsive VGIC Kv7.1 (KCNQ1)28-31 reveals a shared role for the equivalent pore domain intersubunit interface in lipid modulation, providing a framework for dissecting the effects of PUFAs on the VGIC superfamily. Our findings reveal the unique architecture underlying K2P13.1 (THIK-1) function, highlight the importance of the P1/M4 interface in control of K2Ps by both natural and synthetic agents, and should aid development of THIK subfamily modulators for diseases such as neuroinflammation6,32 and autism6.
Collapse
Affiliation(s)
- Shatabdi Roy-Chowdhury
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Seil Jang
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Fayal Abderemane-Ali
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Fiona Naughton
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Michael Grabe
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, California 93858-2330 USA
| | - Daniel L. Minor
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
- Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, California 93858-2330 USA
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, California 93858-2330 USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, California 93858-2330 USA
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| |
Collapse
|
5
|
Türkaydin B, Schewe M, Riel EB, Schulz F, Biedermann J, Baukrowitz T, Sun H. Atomistic mechanism of coupling between cytosolic sensor domain and selectivity filter in TREK K2P channels. Nat Commun 2024; 15:4628. [PMID: 38821927 PMCID: PMC11143257 DOI: 10.1038/s41467-024-48823-y] [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: 10/13/2023] [Accepted: 05/15/2024] [Indexed: 06/02/2024] Open
Abstract
The two-pore domain potassium (K2P) channels TREK-1 and TREK-2 link neuronal excitability to a variety of stimuli including mechanical force, lipids, temperature and phosphorylation. This regulation involves the C-terminus as a polymodal stimulus sensor and the selectivity filter (SF) as channel gate. Using crystallographic up- and down-state structures of TREK-2 as a template for full atomistic molecular dynamics (MD) simulations, we reveal that the SF in down-state undergoes inactivation via conformational changes, while the up-state structure maintains a stable and conductive SF. This suggests an atomistic mechanism for the low channel activity previously assigned to the down state, but not evident from the crystal structure. Furthermore, experimentally by using (de-)phosphorylation mimics and chemically attaching lipid tethers to the proximal C-terminus (pCt), we confirm the hypothesis that moving the pCt towards the membrane induces the up-state. Based on MD simulations, we propose two gating pathways by which movement of the pCt controls the stability (i.e., conductivity) of the filter gate. Together, these findings provide atomistic insights into the SF gating mechanism and the physiological regulation of TREK channels by phosphorylation.
Collapse
Affiliation(s)
- Berke Türkaydin
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
- Insitute of Chemistry, Technical University of Berlin, Berlin, Germany
| | - Marcus Schewe
- Institute of Physiology, Kiel University, Kiel, Germany.
| | - Elena Barbara Riel
- Institute of Physiology, Kiel University, Kiel, Germany
- Department of Anesthesiology, Weill Cornell Medical College, New York, USA
| | | | - Johann Biedermann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | | | - Han Sun
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.
- Insitute of Chemistry, Technical University of Berlin, Berlin, Germany.
| |
Collapse
|
6
|
Zhi Y, Wu X, Chen Y, Chen X, Chen X, Luo H, Yi X, Lin X, Ma L, Chen Y, Cao Y, Li F, Zhou P. A novel TWIK2 channel inhibitor binds at the bottom of the selectivity filter and protects against LPS-induced experimental endotoxemia in vivo. Biochem Pharmacol 2023; 218:115894. [PMID: 37898389 DOI: 10.1016/j.bcp.2023.115894] [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: 08/26/2023] [Revised: 10/24/2023] [Accepted: 10/25/2023] [Indexed: 10/30/2023]
Abstract
TWIK2 channel plays a critical role in NLRP3 inflammasome activation and mice deficient in TWIK2 channel are protected from sepsis and inflammatory lung injury. However, inhibitors of TWIK2 channel are currently in an early stage of development, and the molecular determinants underlying the chemical modulation of TWIK2 channel remain unexplored. In this study, we identified NPBA and the synthesized derivative NPBA-4 potently and selectively inhibited TWIK2 channel by using whole-cell patch clamp techniques. Furthermore, the mutation of the last residues of the selectivity filter in both P1 and P2 (i.e., T106A, T214A) of TWIK2 channel substantially abolished the effect of NPBA on TWIK2 channel. Our data suggest that NPBA blocked TWIK2 channel through binding at the bottom of the selectivity filter, which was also supported by molecular docking prediction. Moreover, we found that NPBA significantly suppressed NLRP3 inflammasome activation in macrophages and alleviated LPS-induced endotoxemia and organ injury in vivo. Notably, the protective effects of NPBA against LPS-induced endotoxemia were abolished in Kcnk6-/- mice. In summary, our study has uncovered a series of novel inhibitors of TWIK2 channel and revealed their distinct molecular determinants interacting TWIK2 channel. These findings provide new insights into the mechanisms of pharmacological action on TWIK2 channel and opportunities for the development of selective TWIK2 channel modulators to treat related inflammatory diseases.
Collapse
Affiliation(s)
- Yuanxing Zhi
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China; Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, Guangzhou 510282, China
| | - Xiaoyan Wu
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yanshan Chen
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Xingyuan Chen
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Xiangyu Chen
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Hui Luo
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Xin Yi
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Xiuling Lin
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Liang Ma
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yao Chen
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, Guangzhou 510282, China
| | - Ying Cao
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Fengxian Li
- Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, Guangzhou 510282, China
| | - Pingzheng Zhou
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China; Department of Anesthesiology, Zhujiang Hospital of Southern Medical University, Guangzhou 510282, China.
| |
Collapse
|
7
|
Deal PE, Lee H, Mondal A, Lolicato M, de Mendonca PRF, Black H, El-Hilali X, Bryant C, Isacoff EY, Renslo AR, Minor DL. Development of covalent chemogenetic K 2P channel activators. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.15.561774. [PMID: 37905049 PMCID: PMC10614804 DOI: 10.1101/2023.10.15.561774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
K2P potassium channels regulate excitability by affecting cellular resting membrane potential in the brain, cardiovascular system, immune cells, and sensory organs. Despite their important roles in anesthesia, arrhythmia, pain, hypertension, sleep, and migraine, the ability to control K2P function remains limited. Here, we describe a chemogenetic strategy termed CATKLAMP (Covalent Activation of TREK family K+ channels to cLAmp Membrane Potential) that leverages the discovery of a site in the K2P modulator pocket that reacts with electrophile-bearing derivatives of a TREK subfamily small molecule activator, ML335, to activate the channel irreversibly. We show that the CATKLAMP strategy can be used to probe fundamental aspects of K2P function, as a switch to silence neuronal firing, and is applicable to all TREK subfamily members. Together, our findings exemplify a new means to alter K2P channel activity that should facilitate studies both molecular and systems level studies of K2P function and enable the search for new K2P modulators.
Collapse
Affiliation(s)
- Parker E. Deal
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 93858-2330 USA
| | - Haerim Lee
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Abhisek Mondal
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | - Marco Lolicato
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
| | | | - Holly Black
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, United States
| | - Xochina El-Hilali
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 93858-2330 USA
| | - Clifford Bryant
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 93858-2330 USA
| | - Ehud Y. Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, United States
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California 94720, United States
- Weill Neurohub, University of California, Berkeley, Berkeley, California 94720, United States
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
| | - Adam R. Renslo
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 93858-2330 USA
| | - Daniel L. Minor
- Cardiovascular Research Institute, University of California, San Francisco, California 93858-2330 USA
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA
- Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, California 93858-2330 USA
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, California 93858-2330 USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, California 93858-2330 USA
| |
Collapse
|
8
|
Schreiber JA, Derksen A, Goerges G, Schütte S, Sörgel J, Kiper AK, Strutz-Seebohm N, Ruck T, Meuth SG, Decher N, Seebohm G. Cloxyquin activates hTRESK by allosteric modulation of the selectivity filter. Commun Biol 2023; 6:745. [PMID: 37464013 PMCID: PMC10354012 DOI: 10.1038/s42003-023-05114-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 07/07/2023] [Indexed: 07/20/2023] Open
Abstract
The TWIK-related spinal cord K+ channel (TRESK, K2P18.1) is a K2P channel contributing to the maintenance of membrane potentials in various cells. Recently, physiological TRESK function was identified as a key player in T-cell differentiation rendering the channel a new pharmacological target for treatment of autoimmune diseases. The channel activator cloxyquin represents a promising lead compound for the development of a new class of immunomodulators. Identification of cloxyquin binding site and characterization of the molecular activation mechanism can foster the future drug development. Here, we identify the cloxyquin binding site at the M2/M4 interface by mutational scan and analyze the molecular mechanism of action by protein modeling as well as in silico and in vitro electrophysiology using different permeating ion species (K+ / Rb+). In combination with kinetic analyses of channel inactivation, our results suggest that cloxyquin allosterically stabilizes the inner selectivity filter facilitating the conduction process subsequently activating hTRESK.
Collapse
Affiliation(s)
- Julian Alexander Schreiber
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany.
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany.
| | - Anastasia Derksen
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany
| | - Gunnar Goerges
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
| | - Sven Schütte
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Jasmin Sörgel
- Westfälische Wilhelms-Universität Münster, Institut für Pharmazeutische und Medizinische Chemie, Corrensstr. 48, Münster, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Nathalie Strutz-Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
| | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Sven G Meuth
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University Marburg, Marburg, Germany
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, Robert-Koch-Str. 45, Münster, Germany
- Westfälische Wilhelms-Universität Münster, GRK 2515, Chemical biology of ion channels (Chembion), Münster, Germany
| |
Collapse
|
9
|
Herrera-Pérez S, Lamas JA. TREK channels in Mechanotransduction: a Focus on the Cardiovascular System. Front Cardiovasc Med 2023; 10:1180242. [PMID: 37288256 PMCID: PMC10242076 DOI: 10.3389/fcvm.2023.1180242] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 04/26/2023] [Indexed: 06/09/2023] Open
Abstract
Mechano-electric feedback is one of the most important subsystems operating in the cardiovascular system, but the underlying molecular mechanism remains rather unknown. Several proteins have been proposed to explain the molecular mechanism of mechano-transduction. Transient receptor potential (TRP) and Piezo channels appear to be the most important candidates to constitute the molecular mechanism behind of the inward current in response to a mechanical stimulus. However, the inhibitory/regulatory processes involving potassium channels that operate on the cardiac system are less well known. TWIK-Related potassium (TREK) channels have emerged as strong candidates due to their capacity for the regulation of the flow of potassium in response to mechanical stimuli. Current data strongly suggest that TREK channels play a role as mechano-transducers in different components of the cardiovascular system, not only at central (heart) but also at peripheral (vascular) level. In this context, this review summarizes and highlights the main existing evidence connecting this important subfamily of potassium channels with the cardiac mechano-transduction process, discussing molecular and biophysical aspects of such a connection.
Collapse
Affiliation(s)
- Salvador Herrera-Pérez
- Laboratory of Neuroscience, CINBIO, University of Vigo, Vigo, Spain
- Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
| | - José Antonio Lamas
- Laboratory of Neuroscience, CINBIO, University of Vigo, Vigo, Spain
- Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
| |
Collapse
|
10
|
Schmidpeter PAM, Petroff JT, Khajoueinejad L, Wague A, Frankfater C, Cheng WWL, Nimigean CM, Riegelhaupt PM. Membrane phospholipids control gating of the mechanosensitive potassium leak channel TREK1. Nat Commun 2023; 14:1077. [PMID: 36841877 PMCID: PMC9968290 DOI: 10.1038/s41467-023-36765-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/15/2023] [Indexed: 02/27/2023] Open
Abstract
Tandem pore domain (K2P) potassium channels modulate resting membrane potentials and shape cellular excitability. For the mechanosensitive subfamily of K2Ps, the composition of phospholipids within the bilayer strongly influences channel activity. To examine the molecular details of K2P lipid modulation, we solved cryo-EM structures of the TREK1 K2P channel bound to either the anionic lipid phosphatidic acid (PA) or the zwitterionic lipid phosphatidylethanolamine (PE). At the extracellular face of TREK1, a PA lipid inserts its hydrocarbon tail into a pocket behind the selectivity filter, causing a structural rearrangement that recapitulates mutations and pharmacology known to activate TREK1. At the cytoplasmic face, PA and PE lipids compete to modulate the conformation of the TREK1 TM4 gating helix. Our findings demonstrate two distinct pathways by which anionic lipids enhance TREK1 activity and provide a framework for a model that integrates lipid gating with the effects of other mechanosensitive K2P modulators.
Collapse
Affiliation(s)
| | - John T Petroff
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Leila Khajoueinejad
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Aboubacar Wague
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA
| | - Cheryl Frankfater
- Department of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - 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
- Department of Biochemistry, Weill Cornell Medical College, New York, NY, USA
| | - Paul M Riegelhaupt
- Department of Anesthesiology, Weill Cornell Medical College, New York, NY, USA.
| |
Collapse
|
11
|
Pope L, Minor DL. The Polysite Pharmacology of TREK K 2P Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1349:51-65. [PMID: 35138610 DOI: 10.1007/978-981-16-4254-8_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
K2P (KCNK) potassium channels form "background" or "leak" currents that have critical roles in cell excitability control in the brain, cardiovascular system, and somatosensory neurons. Similar to many ion channel families, studies of K2Ps have been limited by poor pharmacology. Of six K2P subfamilies, the thermo- and mechanosensitive TREK subfamily comprising K2P2.1 (TREK-1), K2P4.1 (TRAAK), and K2P10.1 (TREK-2) are the first to have structures determined for each subfamily member. These structural studies have revealed key architectural features that underlie K2P function and have uncovered sites residing at every level of the channel structure with respect to the membrane where small molecules or lipids can control channel function. This polysite pharmacology within a relatively small (~70 kDa) ion channel comprises four structurally defined modulator binding sites that occur above (Keystone inhibitor site), at the level of (K2P modulator pocket), and below (Fenestration and Modulatory lipid sites) the C-type selectivity filter gate that is at the heart of K2P function. Uncovering this rich structural landscape provides the framework for understanding and developing subtype-selective modulators to probe K2P function that may provide leads for drugs for anesthesia, pain, arrhythmia, ischemia, and migraine.
Collapse
Affiliation(s)
- Lianne Pope
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, US
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, US. .,Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA. .,California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA, USA. .,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA, USA. .,Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| |
Collapse
|
12
|
Riel EB, Jürs BC, Cordeiro S, Musinszki M, Schewe M, Baukrowitz T. The versatile regulation of K2P channels by polyanionic lipids of the phosphoinositide and fatty acid metabolism. J Gen Physiol 2022; 154:212926. [PMID: 34928298 PMCID: PMC8693234 DOI: 10.1085/jgp.202112989] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 12/01/2021] [Indexed: 12/29/2022] Open
Abstract
Work over the past three decades has greatly advanced our understanding of the regulation of Kir K+ channels by polyanionic lipids of the phosphoinositide (e.g., PIP2) and fatty acid metabolism (e.g., oleoyl-CoA). However, comparatively little is known regarding the regulation of the K2P channel family by phosphoinositides and by long-chain fatty acid–CoA esters, such as oleoyl-CoA. We screened 12 mammalian K2P channels and report effects of polyanionic lipids on all tested channels. We observed activation of members of the TREK, TALK, and THIK subfamilies, with the strongest activation by PIP2 for TRAAK and the strongest activation by oleoyl-CoA for TALK-2. By contrast, we observed inhibition for members of the TASK and TRESK subfamilies. Our results reveal that TASK-2 channels have both activatory and inhibitory PIP2 sites with different affinities. Finally, we provided evidence that PIP2 inhibition of TASK-1 and TASK-3 channels is mediated by closure of the recently identified lower X-gate as critical mutations within the gate (i.e., L244A, R245A) prevent PIP2-induced inhibition. Our findings establish that K+ channels of the K2P family are highly sensitive to polyanionic lipids, extending our knowledge of the mechanisms of lipid regulation and implicating the metabolism of these lipids as possible effector pathways to regulate K2P channel activity.
Collapse
Affiliation(s)
- Elena B Riel
- Institute of Physiology, Kiel University, Kiel, Germany
| | - Björn C Jürs
- Institute of Physiology, Kiel University, Kiel, Germany.,Medical School Hamburg, University of Applied Sciences and Medical University, Hamburg, Germany
| | | | | | - Marcus Schewe
- Institute of Physiology, Kiel University, Kiel, Germany
| | | |
Collapse
|
13
|
Zhang Q, Fu J, Zhang S, Guo P, Liu S, Shen J, Guo J, Yang H. 'C-type' closed state and gating mechanisms of K2P channels revealed by conformational changes of the TREK-1 channel. J Mol Cell Biol 2022; 14:6504012. [PMID: 35022758 PMCID: PMC9021975 DOI: 10.1093/jmcb/mjac002] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/04/2022] [Accepted: 01/07/2022] [Indexed: 01/10/2023] Open
Abstract
Two-pore domain potassium (K2P) channels gate primarily within the selectivity filter, termed ‘C-type’ gating. Due to the lack of structural insights into the nonconductive (closed) state, ‘C-type’ gating mechanisms remain elusive. Here, molecular dynamics (MD) simulations on TREK-1, a K2P channel, revealed that M4 helix movements induce filter closing in a novel ‘deeper-down’ structure that represents a ‘C-type’ closed state. The ‘down’ structure does not represent the closed state as previously proposed and instead acts as an intermediate state in gating. The study identified the allosteric ‘seesaw’ mechanism of M4 helix movements in modulating filter closing. Finally, guided by this recognition of K2P gating mechanisms, MD simulations revealed that gain-of-function mutations and small-molecule activators activate TREK-1 by perturbing state transitions from open to closed states. Together, we reveal a ‘C-type’ closed state and provide mechanical insights into gating procedures and allosteric regulations for K2P channels.
Collapse
Affiliation(s)
- Qiansen Zhang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Jie Fu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Shaoying Zhang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Peipei Guo
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Shijie Liu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Juwen Shen
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Jiangtao Guo
- Department of Biophysics, and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Huaiyu Yang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, School of Life Sciences, East China Normal University, Shanghai 200241, China
| |
Collapse
|
14
|
Rueda-Ruzafa L, Herrera-Pérez S, Campos-Ríos A, Lamas JA. Are TREK Channels Temperature Sensors? Front Cell Neurosci 2021; 15:744702. [PMID: 34690704 PMCID: PMC8526543 DOI: 10.3389/fncel.2021.744702] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022] Open
Abstract
Internal human body normal temperature fluctuates between 36.5 and 37.5°C and it is generally measured in the oral cavity. Interestingly, most electrophysiological studies on the functioning of ion channels and their role in neuronal behavior are carried out at room temperature, which usually oscillates between 22 and 24°C, even when thermosensitive channels are studied. We very often forget that if the core of the body reached that temperature, the probability of death from cardiorespiratory arrest would be extremely high. Does this mean that we are studying ion channels in dying neurons? Thousands of electrophysiological experiments carried out at these low temperatures suggest that most neurons tolerate this aggression quite well, at least for the duration of the experiments. This also seems to happen with ion channels, although studies at different temperatures indicate large changes in both, neuron and channel behavior. It is known that many chemical, physical and therefore physiological processes, depend to a great extent on body temperature. Temperature clearly affects the kinetics of numerous events such as chemical reactions or conformational changes in proteins but, what if these proteins constitute ion channels and these channels are specifically designed to detect changes in temperature? In this review, we discuss the importance of the potassium channels of the TREK subfamily, belonging to the recently discovered family of two-pore domain channels, in the transduction of thermal sensitivity in different cell types.
Collapse
Affiliation(s)
- Lola Rueda-Ruzafa
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
| | - Salvador Herrera-Pérez
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Grupo de Neurofisiología Experimental y Circuitos Neuronales, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain
| | - Ana Campos-Ríos
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
| | - J A Lamas
- CINBIO, Laboratory of Neuroscience, University of Vigo, Vigo, Spain.,Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), Vigo, Spain
| |
Collapse
|
15
|
Choveau FS, Ben Soussia I, Bichet D, Franck CC, Feliciangeli S, Lesage F. Convergence of Multiple Stimuli to a Single Gate in TREK1 and TRAAK Potassium Channels. Front Pharmacol 2021; 12:755826. [PMID: 34658895 PMCID: PMC8514629 DOI: 10.3389/fphar.2021.755826] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 09/15/2021] [Indexed: 11/30/2022] Open
Abstract
Inhibitory potassium channels of the TREK1/TRAAK family are integrators of multiple stimuli, including temperature, membrane stretch, polyunsaturated fatty acids and pH. How these signals affect the gating of these channels is the subject of intense research. We have previously identified a cytoplasmic domain, pCt, which plays a major role in controlling channel activity. Here, we use pharmacology to show that the effects of pCt, arachidonic acid, and extracellular pH converge to the same gate within the channel. Using a state-dependent inhibitor, fluoxetine, as well as natural and synthetic openers, we provide further evidence that the “up” and “down” conformations identified by crystallography do not correspond to open and closed states of these channels.
Collapse
Affiliation(s)
- Frank S Choveau
- Université Côte D'Azur, INSERM, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, Valbonne, France
| | - Ismail Ben Soussia
- Université Côte D'Azur, INSERM, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, Valbonne, France
| | - Delphine Bichet
- Université Côte D'Azur, INSERM, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, Valbonne, France
| | - Chatelain C Franck
- Université Côte D'Azur, INSERM, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, Valbonne, France
| | - Sylvain Feliciangeli
- Université Côte D'Azur, INSERM, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, Valbonne, France
| | - Florian Lesage
- Université Côte D'Azur, INSERM, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, Valbonne, France
| |
Collapse
|
16
|
Cunningham KP, Clapp LH, Mathie A, Veale EL. The Prostacyclin Analogue, Treprostinil, Used in the Treatment of Pulmonary Arterial Hypertension, is a Potent Antagonist of TREK-1 and TREK-2 Potassium Channels. Front Pharmacol 2021; 12:705421. [PMID: 34267666 PMCID: PMC8276018 DOI: 10.3389/fphar.2021.705421] [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: 05/05/2021] [Accepted: 06/14/2021] [Indexed: 11/24/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is an aggressive vascular remodeling disease that carries a high morbidity and mortality rate. Treprostinil (Remodulin) is a stable prostacyclin analogue with potent vasodilatory and anti-proliferative activity, approved by the FDA and WHO as a treatment for PAH. A limitation of this therapy is the severe subcutaneous site pain and other forms of pain experienced by some patients, which can lead to significant non-compliance. TWIK-related potassium channels (TREK-1 and TREK-2) are highly expressed in sensory neurons, where they play a role in regulating sensory neuron excitability. Downregulation, inhibition or mutation of these channels leads to enhanced pain sensitivity. Using whole-cell patch-clamp electrophysiological recordings, we show, for the first time, that treprostinil is a potent antagonist of human TREK-1 and TREK-2 channels but not of TASK-1 channels. An increase in TASK-1 channel current was observed with prolonged incubation, consistent with its therapeutic role in PAH. To investigate treprostinil-induced inhibition of TREK, site-directed mutagenesis of a number of amino acids, identified as important for the action of other regulatory compounds, was carried out. We found that a gain of function mutation of TREK-1 (Y284A) attenuated treprostinil inhibition, while a selective activator of TREK channels, BL-1249, overcame the inhibitory effect of treprostinil. Our data suggests that subcutaneous site pain experienced during treprostinil therapy may result from inhibition of TREK channels near the injection site and that pre-activation of these channels prior to treatment has the potential to alleviate this nociceptive activity.
Collapse
Affiliation(s)
- Kevin P Cunningham
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom.,Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Lucie H Clapp
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Alistair Mathie
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom.,School of Engineering, Arts, Science and Technology, University of Suffolk, Ipswich, United Kingdom
| | - Emma L Veale
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom
| |
Collapse
|
17
|
Enyeart JJ, Enyeart JA. Human adrenal glomerulosa cells express K2P and GIRK potassium channels that are inhibited by ANG II and ACTH. Am J Physiol Cell Physiol 2021; 321:C158-C175. [PMID: 34038243 DOI: 10.1152/ajpcell.00118.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In whole cell patch clamp recordings, it was discovered that normal human adrenal zona glomerulosa (AZG) cells express members of the three major families of K+ channels. Among these are a two-pore (K2P) leak-type and a G protein-coupled, inwardly rectifying (GIRK) channel, both inhibited by peptide hormones that stimulate aldosterone secretion. The K2P current displayed properties identifying it as TREK-1 (KCNK2). This outwardly rectifying current was activated by arachidonic acid and inhibited by angiotensin II (ANG II), adrenocorticotrophic hormone (ACTH), and forskolin. The activation and inhibition of TREK-1 was coupled to AZG cell hyperpolarization and depolarization, respectively. A second K2P channel, TASK-1 (KCNK3), was expressed at a lower density in AZG cells. Human AZG cells also express inwardly rectifying K+ current(s) (KIR) that include quasi-instantaneous and time-dependent components. This is the first report demonstrating the presence of KIR in whole cell recordings from AZG cells of any species. The time-dependent current was selectively inhibited by ANG II, and ACTH, identifying it as a G protein-coupled (GIRK) channel, most likely KIR3.4 (KCNJ5). The quasi-instantaneous KIR current was not inhibited by ANG II or ACTH and may be a separate non-GIRK current. Finally, AZG cells express a voltage-gated, rapidly inactivating K+ current whose properties identified as KV1.4 (KCNA4), a conclusion confirmed by Northern blot. These findings demonstrate that human AZG cells express K2P and GIRK channels whose inhibition by ANG II and ACTH is likely coupled to depolarization-dependent secretion. They further demonstrate that human AZG K+ channels differ fundamentally from the widely adopted rodent models for human aldosterone secretion.
Collapse
Affiliation(s)
- John J Enyeart
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Judith A Enyeart
- Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, Ohio
| |
Collapse
|
18
|
Natale AM, Deal PE, Minor DL. Structural Insights into the Mechanisms and Pharmacology of K 2P Potassium Channels. J Mol Biol 2021; 433:166995. [PMID: 33887333 PMCID: PMC8436263 DOI: 10.1016/j.jmb.2021.166995] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/08/2021] [Accepted: 04/09/2021] [Indexed: 01/10/2023]
Abstract
Leak currents, defined as voltage and time independent flows of ions across cell membranes, are central to cellular electrical excitability control. The K2P (KCNK) potassium channel class comprises an ion channel family that produces potassium leak currents that oppose excitation and stabilize the resting membrane potential in cells in the brain, cardiovascular system, immune system, and sensory organs. Due to their widespread tissue distribution, K2Ps contribute to many physiological and pathophysiological processes including anesthesia, pain, arrythmias, ischemia, hypertension, migraine, intraocular pressure regulation, and lung injury responses. Structural studies of six homomeric K2Ps have established the basic architecture of this channel family, revealed key moving parts involved in K2P function, uncovered the importance of asymmetric pinching and dilation motions in the K2P selectivity filter (SF) C-type gate, and defined two K2P structural classes based on the absence or presence of an intracellular gate. Further, a series of structures characterizing K2P:modulator interactions have revealed a striking polysite pharmacology housed within a relatively modestly sized (~70 kDa) channel. Binding sites for small molecules or lipids that control channel function are found at every layer of the channel structure, starting from its extracellular side through the portion that interacts with the membrane bilayer inner leaflet. This framework provides the basis for understanding how gating cues sensed by different channel parts control function and how small molecules and lipids modulate K2P activity. Such knowledge should catalyze development of new K2P modulators to probe function and treat a wide range of disorders.
Collapse
Affiliation(s)
- Andrew M Natale
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA
| | - Parker E Deal
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA; Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 94158, USA; California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA 94158, USA; Kavli Institute for Fundamental Neuroscience University of California, San Francisco, CA 94158, USA; Molecular Biophysics and Integrated Bio-imaging Division Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| |
Collapse
|
19
|
Lee H, Lolicato M, Arrigoni C, Minor DL. Production of K 2P2.1 (TREK-1) for structural studies. Methods Enzymol 2021; 653:151-188. [PMID: 34099170 DOI: 10.1016/bs.mie.2021.02.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
K2P (KCNK) potassium channels form 'background' or 'leak' currents that are important for controlling cell excitability in the brain, cardiovascular system, and somatosensory neurons. K2P2.1 (TREK-1) is one of the founding members of this family and one of the first well-characterized polymodal ion channels capable of responding to a variety of physical and chemical gating cues. Of the six K2P subfamilies, the thermo-and mechano-sensitive TREK subfamily comprising K2P2.1 (TREK-1), K2P4.1 (TRAAK), and K2P10.1 (TREK-2) is the first to have structures determined for each subfamily member. These structural studies have revealed key architectural features that provide a framework for understanding how gating cues sensed by different channel elements converge on the K2P selectivity filter C-type gate. TREK family structural studies have also revealed numerous sites where small molecules or lipids bind and affect channel function. This rich structural landscape provides the framework for probing K2P function and for the development of new K2P-directed agents. Such molecules may be useful for affecting processes where TREK channels are important such as anesthesia, pain, arrythmia, ischemia, migraine, intraocular pressure, and lung injury. Production of high quality protein samples is key to addressing new questions about K2P function and pharmacology. Here, we present methods for producing pure K2P2.1 (TREK-1) suitable for advancing towards these goals through structural and biochemical studies.
Collapse
Affiliation(s)
- Haerim Lee
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States
| | - Marco Lolicato
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States
| | - Cristina Arrigoni
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, CA, United States; Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA, United States; California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA, United States; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA, United States; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
| |
Collapse
|
20
|
Abstract
Two-pore domain potassium channels are formed by subunits that each contain two pore-loops moieties. Whether the channels are expressed in yeast or the human central nervous system, two subunits come together to form a single potassium selective pore. TOK1, the first two-domain channel was cloned from Saccharomyces cerevisiae in 1995 and soon thereafter, 15 distinct K2P subunits were identified in the human genome. The human K2P channels are stratified into six K2P subfamilies based on sequence as well as physiological or pharmacological similarities. Functional K2P channels pass background (or "leak") K+ currents that shape the membrane potential and excitability of cells in a broad range of tissues. In the years since they were first described, classical functional assays, latterly coupled with state-of-the-art structural and computational studies have revealed the mechanistic basis of K2P channel gating in response to specific physicochemical or pharmacological stimuli. The growing appreciation that K2P channels can play a pivotal role in the pathophysiology of a growing spectrum of diseases makes a compelling case for K2P channels as targets for drug discovery. Here, we summarize recent advances in unraveling the structure, function, and pharmacology of the K2P channels.
Collapse
Affiliation(s)
- Jordie M Kamuene
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Yu Xu
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Leigh D Plant
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA.
| |
Collapse
|
21
|
Wague A, Joseph TT, Woll KA, Bu W, Vaidya KA, Bhanu NV, Garcia BA, Nimigean CM, Eckenhoff RG, Riegelhaupt PM. Mechanistic insights into volatile anesthetic modulation of K2P channels. eLife 2020; 9:59839. [PMID: 33345771 PMCID: PMC7781597 DOI: 10.7554/elife.59839] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 12/19/2020] [Indexed: 01/01/2023] Open
Abstract
K2P potassium channels are known to be modulated by volatile anesthetic (VA) drugs and play important roles in clinically relevant effects that accompany general anesthesia. Here, we utilize a photoaffinity analog of the VA isoflurane to identify a VA-binding site in the TREK1 K2P channel. The functional importance of the identified site was validated by mutagenesis and biochemical modification. Molecular dynamics simulations of TREK1 in the presence of VA found multiple neighboring residues on TREK1 TM2, TM3, and TM4 that contribute to anesthetic binding. The identified VA-binding region contains residues that play roles in the mechanisms by which heat, mechanical stretch, and pharmacological modulators alter TREK1 channel activity and overlaps with positions found to modulate TASK K2P channel VA sensitivity. Our findings define molecular contacts that mediate VA binding to TREK1 channels and suggest a mechanistic basis to explain how K2P channels are modulated by VAs.
Collapse
Affiliation(s)
- Aboubacar Wague
- Department of Anesthesiology, Weill Cornell Medical College, New York City, United States
| | - Thomas T Joseph
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, United States
| | - Kellie A Woll
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, United States
| | - Weiming Bu
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, United States
| | - Kiran A Vaidya
- Department of Anesthesiology, Weill Cornell Medical College, New York City, United States
| | - Natarajan V Bhanu
- Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Benjamin A Garcia
- Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medical College, New York City, United States.,Department of Physiology and Biophysics, Weill Cornell Medical College, New York City, United States.,Department of Biochemistry, Weill Cornell Medical College, New York City, United States
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, United States
| | - Paul M Riegelhaupt
- Department of Anesthesiology, Weill Cornell Medical College, New York City, United States
| |
Collapse
|
22
|
Mukherjee S, Sikdar SK. Intracellular activation of full-length human TREK-1 channel by hypoxia, high lactate, and low pH denotes polymodal integration by ischemic factors. Pflugers Arch 2020; 473:167-183. [PMID: 33025137 DOI: 10.1007/s00424-020-02471-5] [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: 09/01/2020] [Revised: 09/18/2020] [Accepted: 09/30/2020] [Indexed: 10/23/2022]
Abstract
TREK-1, a two-pore domain potassium channel, responds to ischemic levels of intracellular lactate and acidic pH to provide neuroprotection. There are two splice variants of hTREK1: the shorter splice variant having a shorter N-terminus compared with the full-length hTREK1 with similar C-terminus sequence that is widely expressed in the brain. The shorter variant was reported to be irresponsive to hypoxia-a condition attributed to ischemia, which has put the neuroprotective role of hTREK-1 channel into question. Since interaction between N- and C-terminus of different ion channels shapes their gating, we re-examined the sensitivity of the full-length as well as the shorter hTREK-1 channel to intracellular hypoxia along with lactate. Single-channel data obtained from the excised inside-out patches of the full-length channel expressed in HEK293 cells indicated an increase in activity as opposed to a decrease in activity in the shorter isoform. However, both the isoforms showed an increase in activity under combined hypoxia, 20mM lactate, and low pH 6 condition, albeit with subtle differences in their individual actions, confirming the neuroprotective role played by hTREK-1 irrespective of the differences in the N-terminus among the splice variants. Furthermore, E321A mutant that disrupts the interaction of the C-terminus with the membrane showed a decrease in activity with hypoxia indicating the importance of the C-terminus in the hypoxic response of the full-length hTREK-1. We propose an increase in activity of both the splice variants of hTREK-1 in combined hypoxia, high lactate, and low pH conditions typically associated with ischemia provides neuroprotection.
Collapse
Affiliation(s)
- Sourajit Mukherjee
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Sujit Kumar Sikdar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India.
| |
Collapse
|
23
|
Lolicato M, Natale AM, Abderemane-Ali F, Crottès D, Capponi S, Duman R, Wagner A, Rosenberg JM, Grabe M, Minor DL. K 2P channel C-type gating involves asymmetric selectivity filter order-disorder transitions. SCIENCE ADVANCES 2020; 6:6/44/eabc9174. [PMID: 33127683 PMCID: PMC7608817 DOI: 10.1126/sciadv.abc9174] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 09/10/2020] [Indexed: 05/05/2023]
Abstract
K2P potassium channels regulate cellular excitability using their selectivity filter (C-type) gate. C-type gating mechanisms, best characterized in homotetrameric potassium channels, remain controversial and are attributed to selectivity filter pinching, dilation, or subtle structural changes. The extent to which such mechanisms control C-type gating of innately heterodimeric K2Ps is unknown. Here, combining K2P2.1 (TREK-1) x-ray crystallography in different potassium concentrations, potassium anomalous scattering, molecular dynamics, and electrophysiology, we uncover unprecedented, asymmetric, potassium-dependent conformational changes that underlie K2P C-type gating. These asymmetric order-disorder transitions, enabled by the K2P heterodimeric architecture, encompass pinching and dilation, disrupt the S1 and S2 ion binding sites, require the uniquely long K2P SF2-M4 loop and conserved "M3 glutamate network," and are suppressed by the K2P C-type gate activator ML335. These findings demonstrate that two distinct C-type gating mechanisms can operate in one channel and underscore the SF2-M4 loop as a target for K2P channel modulator development.
Collapse
Affiliation(s)
- Marco Lolicato
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA
| | - Andrew M Natale
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA
| | - Fayal Abderemane-Ali
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA
| | - David Crottès
- Department of Physiology, University of California, San Francisco, CA 93858-2330, USA
| | - Sara Capponi
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA
| | - Ramona Duman
- Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Armin Wagner
- Science Division, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - John M Rosenberg
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Michael Grabe
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA.
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 93858-2330, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA.
- Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 93858-2330, USA
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA 93858-2330, USA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA, 93858-2330, USA
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720 USA
| |
Collapse
|
24
|
Tu N, Liang D, Zhang P. Whole-exome sequencing and genome-wide evolutionary analyses identify novel candidate genes associated with infrared perception in pit vipers. Sci Rep 2020; 10:13033. [PMID: 32747674 PMCID: PMC7400743 DOI: 10.1038/s41598-020-69843-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 07/14/2020] [Indexed: 12/17/2022] Open
Abstract
Pit vipers possess a unique thermal sensory system consisting of facial pits that allow them to detect minute temperature fluctuations within their environments. Biologists have long attempted to elucidate the genetic basis underlying the infrared perception of pit vipers. Early studies have shown that the TRPA1 gene is the thermal sensor associated with infrared detection in pit vipers. However, whether genes other than TRPA1 are also involved in the infrared perception of pit vipers remains unknown. Here, we sequenced the whole exomes of ten snake species and performed genome-wide evolutionary analyses to search for novel candidate genes that might be involved in the infrared perception of pit vipers. We applied both branch-length-comparison and selection-pressure-alteration analyses to identify genes that specifically underwent accelerated evolution in the ancestral lineage of pit vipers. A total of 47 genes were identified. These genes were significantly enriched in the ion transmembrane transporter, stabilization of membrane potential, and temperature gating activity functional categories. The expression levels of these candidate genes in relevant nerve tissues (trigeminal ganglion, dorsal root ganglion, midbrain, and cerebrum) were also investigated in this study. We further chose one of our candidate genes, the potassium channel gene KCNK4, as an example to discuss its possible role in the infrared perception of pit vipers. Our study provides the first genome-wide survey of infrared perception-related genes in pit vipers via comparative evolutionary analyses and reveals valuable candidate genes for future functional studies.
Collapse
Affiliation(s)
- Na Tu
- State Key Laboratory of Biocontrol, College of Ecology and Evolution, School of Life Sciences, Higher Education Mega Center, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Dan Liang
- State Key Laboratory of Biocontrol, College of Ecology and Evolution, School of Life Sciences, Higher Education Mega Center, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Peng Zhang
- State Key Laboratory of Biocontrol, College of Ecology and Evolution, School of Life Sciences, Higher Education Mega Center, Sun Yat-Sen University, Guangzhou, 510006, China.
| |
Collapse
|
25
|
Mathie A, Veale EL, Cunningham KP, Holden RG, Wright PD. Two-Pore Domain Potassium Channels as Drug Targets: Anesthesia and Beyond. Annu Rev Pharmacol Toxicol 2020; 61:401-420. [PMID: 32679007 DOI: 10.1146/annurev-pharmtox-030920-111536] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Two-pore domain potassium (K2P) channels stabilize the resting membrane potential of both excitable and nonexcitable cells and, as such, are important regulators of cell activity. There are many conditions where pharmacological regulation of K2P channel activity would be of therapeutic benefit, including, but not limited to, atrial fibrillation, respiratory depression, pulmonary hypertension, neuropathic pain, migraine, depression, and some forms of cancer. Up until now, few if any selective pharmacological regulators of K2P channels have been available. However, recent publications of solved structures with small-molecule activators and inhibitors bound to TREK-1, TREK-2, and TASK-1 K2P channels have given insight into the pharmacophore requirements for compound binding to these sites. Together with the increasing availability of a number of novel, active, small-molecule compounds from K2P channel screening programs, these advances have opened up the possibility of rational activator and inhibitor design to selectively target K2P channels.
Collapse
Affiliation(s)
- Alistair Mathie
- Medway School of Pharmacy, University of Greenwich and University of Kent, Kent ME4 4TB, United Kingdom;
| | - Emma L Veale
- Medway School of Pharmacy, University of Greenwich and University of Kent, Kent ME4 4TB, United Kingdom;
| | - Kevin P Cunningham
- Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
| | - Robyn G Holden
- Medway School of Pharmacy, University of Greenwich and University of Kent, Kent ME4 4TB, United Kingdom;
| | | |
Collapse
|
26
|
Pope L, Lolicato M, Minor DL. Polynuclear Ruthenium Amines Inhibit K 2P Channels via a "Finger in the Dam" Mechanism. Cell Chem Biol 2020; 27:511-524.e4. [PMID: 32059793 PMCID: PMC7245552 DOI: 10.1016/j.chembiol.2020.01.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/16/2020] [Accepted: 01/27/2020] [Indexed: 12/11/2022]
Abstract
The trinuclear ruthenium amine ruthenium red (RuR) inhibits diverse ion channels, including K2P potassium channels, TRPs, the calcium uniporter, CALHMs, ryanodine receptors, and Piezos. Despite this extraordinary array, there is limited information for how RuR engages targets. Here, using X-ray crystallographic and electrophysiological studies of an RuR-sensitive K2P, K2P2.1 (TREK-1) I110D, we show that RuR acts by binding an acidic residue pair comprising the "Keystone inhibitor site" under the K2P CAP domain archway above the channel pore. We further establish that Ru360, a dinuclear ruthenium amine not known to affect K2Ps, inhibits RuR-sensitive K2Ps using the same mechanism. Structural knowledge enabled a generalizable design strategy for creating K2P RuR "super-responders" having nanomolar sensitivity. Together, the data define a "finger in the dam" inhibition mechanism acting at a novel K2P inhibitor binding site. These findings highlight the polysite nature of K2P pharmacology and provide a new framework for K2P inhibitor development.
Collapse
Affiliation(s)
- Lianne Pope
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA
| | - Marco Lolicato
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, CA 93858-2330, USA; Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA 93858-2330, USA; California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA 93858-2330, USA; Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA 93858-2330, USA; Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| |
Collapse
|
27
|
Arazi E, Blecher G, Zilberberg N. A regulatory domain in the K 2P2.1 (TREK-1) carboxyl-terminal allows for channel activation by monoterpenes. Mol Cell Neurosci 2020; 105:103496. [PMID: 32320829 DOI: 10.1016/j.mcn.2020.103496] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 04/12/2020] [Accepted: 04/15/2020] [Indexed: 11/30/2022] Open
Abstract
Potassium K2P ('leak') channels conduct current across the entire physiological voltage range and carry leak or 'background' currents that are, in part, time- and voltage-independent. K2P2.1 channels (i.e., TREK-1, KCNK2) are highly expressed in excitable tissues, where they play a key role in the cellular mechanisms of neuroprotection, anesthesia, pain perception, and depression. Here, we report for the first time that human K2P2.1 channel activity is regulated by monoterpenes (MTs). We found that cyclic, aromatic monoterpenes containing a phenol moiety, such as carvacrol, thymol and 4-IPP had the most profound effect on current flowing through the channel (up to a 6-fold increase). By performing sequential truncation of the carboxyl-terminal domain of the channel and testing the activity of several channel regulators, we identified two distinct regulatory domains within this portion of the protein. One domain, as previously reported, was needed for regulation by arachidonic acid, anionic phospholipids, and temperature changes. Within a second domain, a triple arginine residue motif (R344-346), an apparent PIP2-binding site, was found to be essential for regulation by holding potential changes and important for regulation by monoterpenes.
Collapse
Affiliation(s)
- Eden Arazi
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel
| | - Galit Blecher
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel
| | - Noam Zilberberg
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel; Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, P.O.B. 653, Beer-Sheva 8410501, Israel.
| |
Collapse
|
28
|
Cunningham KP, MacIntyre DE, Mathie A, Veale EL. Effects of the ventilatory stimulant, doxapram on human TASK-3 (KCNK9, K2P9.1) channels and TASK-1 (KCNK3, K2P3.1) channels. Acta Physiol (Oxf) 2020; 228:e13361. [PMID: 31423744 PMCID: PMC7003846 DOI: 10.1111/apha.13361] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 08/14/2019] [Accepted: 08/15/2019] [Indexed: 01/16/2023]
Abstract
AIMS The mode of action by which doxapram acts as a respiratory stimulant in humans is controversial. Studies in rodent models, have shown that doxapram is a more potent and selective inhibitor of TASK-1 and TASK-1/TASK-3 heterodimer channels, than TASK-3. Here we investigate the direct effect of doxapram and chirally separated, individual positive and negative enantiomers of the compound, on both human and mouse, homodimeric and heterodimeric variants of TASK-1 and TASK-3. METHODS Whole-cell patch clamp electrophysiology on tsA201 cells was used to assess the potency of doxapram on cloned human or mouse TASK-1, TASK-3 and TASK-2 channels. Mutations of amino acids in the pore-lining region of TASK-3 channels were introduced using site-directed mutagenesis. RESULTS Doxapram was an equipotent inhibitor of human TASK-1 and TASK-3 channels, compared with mouse channel variants, where it was more selective for TASK-1 and heterodimers of TASK-1 and TASK-3. The effect of doxapram could be attenuated by either the removal of the C-terminus of human TASK-3 channels or mutations of particular hydrophobic residues in the pore-lining region. These mutations, however, did not alter the effect of a known extracellular inhibitor of TASK-3, zinc. The positive enantiomer of doxapram, GAL-054, was a more potent antagonist of TASK channels, than doxapram, whereas the negative enantiomer, GAL-053, had little inhibitory effect. CONCLUSION These data show that in contrast to rodent channels, doxapram is a potent inhibitor of both TASK-1 and TASK-3 human channels, providing further understanding of the pharmacological profile of doxapram in humans and informing the development of new therapeutic agents.
Collapse
Affiliation(s)
- Kevin P. Cunningham
- Medway School of PharmacyUniversity of Greenwich and University of KentChatham MaritimeUK
| | - D. Euan MacIntyre
- Department of Drug DiscoveryGalleon Pharmaceuticals, IncHorshamPennsylvania
| | - Alistair Mathie
- Medway School of PharmacyUniversity of Greenwich and University of KentChatham MaritimeUK
| | - Emma L. Veale
- Medway School of PharmacyUniversity of Greenwich and University of KentChatham MaritimeUK
| |
Collapse
|
29
|
Mammalian Mechanoelectrical Transduction: Structure and Function of Force-Gated Ion Channels. Cell 2019; 179:340-354. [PMID: 31585078 DOI: 10.1016/j.cell.2019.08.049] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 08/08/2019] [Accepted: 08/26/2019] [Indexed: 12/19/2022]
Abstract
The conversion of force into an electrical cellular signal is mediated by the opening of different types of mechanosensitive ion channels (MSCs), including TREK/TRAAK K2P channels, Piezo1/2, TMEM63/OSCA, and TMC1/2. Mechanoelectrical transduction plays a key role in hearing, balance, touch, and proprioception and is also implicated in the autonomic regulation of blood pressure and breathing. Thus, dysfunction of MSCs is associated with a variety of inherited and acquired disease states. Significant progress has recently been made in identifying these channels, solving their structure, and understanding the gating of both hyperpolarizing and depolarizing MSCs. Besides prototypical activation by membrane tension, additional gating mechanisms involving channel curvature and/or tethered elements are at play.
Collapse
|
30
|
Anderson EO, Schneider ER, Matson JD, Gracheva EO, Bagriantsev SN. TMEM150C/Tentonin3 Is a Regulator of Mechano-gated Ion Channels. Cell Rep 2019; 23:701-708. [PMID: 29669276 PMCID: PMC5929159 DOI: 10.1016/j.celrep.2018.03.094] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 02/21/2018] [Accepted: 03/20/2018] [Indexed: 11/24/2022] Open
Abstract
Neuronal mechano-sensitivity relies on mechano-gated ion channels, but pathways regulating their activity remain poorly understood. TMEM150C was proposed to mediate mechano-activated current in proprioceptive neurons. Here, we studied functional interaction of TMEM150C with mechano-gated ion channels from different classes (Piezo2, Piezo1, and the potassium channel TREK-1) using two independent methods of mechanical stimulation. We found that TMEM150C significantly prolongs the duration of the mechano-current produced by all three channels, decreases apparent activation threshold in Piezo2, and induces persistent current in Piezo1. We also show that TMEM150C is co-expressed with Piezo2 in trigeminal neurons, expanding its role beyond proprioceptors. Finally, we cloned TMEM150C from the trigeminal neurons of the tactile-foraging domestic duck and showed that it functions similarly to the mouse ortholog, demonstrating evolutionary conservation among vertebrates. Our studies reveal TMEM150C as a general regulator of mechano-gated ion channels from different classes.
Collapse
Affiliation(s)
- Evan O Anderson
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Eve R Schneider
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Jon D Matson
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Elena O Gracheva
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Sviatoslav N Bagriantsev
- Department of Cellular & Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, USA.
| |
Collapse
|
31
|
Al-Moubarak E, Veale EL, Mathie A. Pharmacologically reversible, loss of function mutations in the TM2 and TM4 inner pore helices of TREK-1 K2P channels. Sci Rep 2019; 9:12394. [PMID: 31455781 PMCID: PMC6712037 DOI: 10.1038/s41598-019-48855-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/09/2019] [Indexed: 01/21/2023] Open
Abstract
A better understanding of the gating of TREK two pore domain potassium (K2P) channels and their activation by compounds such as the negatively charged activator, flufenamic acid (FFA) is critical in the search for more potent and selective activators of these channels. Currents through wild-type and mutated human K2P channels expressed in tsA201 cells were measured using whole-cell patch-clamp recordings in the presence and absence of FFA. Mutation of the TM2.6 residue of TREK-1 to a phenylalanine (G171F) and a similar mutation of TM4.6 (A286F) substantially reduced current through TREK-1 channels. In complementary experiments, replacing the natural F residues at the equivalent position in TRESK channels, significantly enhanced current. Known, gain of function mutations of TREK-1 (G137I, Y284A) recovered current through these mutated channels. This reduction in current could be also be reversed pharmacologically, by FFA. However, an appropriate length MTS (MethaneThioSulfonate) cross-linking reagent (MTS14) restricted the activation of TREK-1_A286C channels by repeated application of FFA. This suggests that the cross-linker stabilises the channel in a conformation which blunts FFA activation. Pharmacologically reversible mutations of TREK channels will help to clarify the importance of these channels in pathophysiological conditions such as pain and depression.
Collapse
Affiliation(s)
- Ehab Al-Moubarak
- Medway School of Pharmacy, University of Kent, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Emma L Veale
- Medway School of Pharmacy, University of Kent, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Alistair Mathie
- Medway School of Pharmacy, University of Kent, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK.
| |
Collapse
|
32
|
Lv J, Liang Y, Zhang S, Lan Q, Xu Z, Wu X, Kang L, Ren J, Cao Y, Wu T, Lin KL, Yung KKL, Cao X, Pang J, Zhou P. DCPIB, an Inhibitor of Volume-Regulated Anion Channels, Distinctly Modulates K2P Channels. ACS Chem Neurosci 2019; 10:2786-2793. [PMID: 30935201 DOI: 10.1021/acschemneuro.9b00010] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
K2P potassium channels stabilize the resting membrane potential in nearly all cells and have been implicated in several neuronal, cardiovascular, and immune diseases. DCPIB, a known specific and potent inhibitor of volume-regulated anion channels (VRAC), has been reported to activate TREK1 and TREK2 in astrocytes and in vitro recently. In the present study, we demonstrated DCPIB also voltage dependently activated TRAAK besides TREK1/TREK2, showing DCPIB activated all TREK subfamily members. In contrast, the compound potently inhibited several other K2P channels with no voltage dependence, including TRESK, TASK1, and TASK3. DCPIB displayed superior selectivity toward TRESK with an IC50 of 0.14 μM, demonstrating at least 100-fold higher affinity over TREK1/TRAAK channels. Furthermore, the impaired ion selectivity filter region greatly impaired the activating effect of DCPIB on TREK1 but not the inhibitory effect of DCPIB on TRESK. This indicates distinct molecular determinants underlying the effect of DCPIB on TREK1 or TRESK channels. Our results showed that DCPIB played diverse effects on K2P channels and could be a useful tool for further investigating structure-function studies of K2P channels.
Collapse
Affiliation(s)
- Jinyan Lv
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Yemei Liang
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Shiqing Zhang
- Department of Biology, Faculty of Science, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region, China
| | - Qunsheng Lan
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Ziwei Xu
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Xiaoyan Wu
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Lijun Kang
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jing Ren
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Ying Cao
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Ting Wu
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Ka Li Lin
- Department of Biology, Faculty of Science, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region, China
| | - Ken Kin Lam Yung
- Department of Biology, Faculty of Science, Hong Kong Baptist University, Kowloon Tong, Hong Kong Special Administrative Region, China
| | - Xiong Cao
- Key Laboratory of Mental Health of the Ministry of Education, Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Jianxin Pang
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Pingzheng Zhou
- Guangdong Provincial Key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China
| |
Collapse
|
33
|
Şterbuleac D. Molecular determinants of chemical modulation of two-pore domain potassium channels. Chem Biol Drug Des 2019; 94:1596-1614. [PMID: 31124599 DOI: 10.1111/cbdd.13571] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/29/2019] [Accepted: 05/05/2019] [Indexed: 12/16/2022]
Abstract
The K+ ion channels comprising the two-pore domain (K2P) family have specific biophysical roles in generating the critical regulatory K+ current. Ion flow through K2P channels and, implicitly, channel regulation is mediated by diverse metabolic and physical inputs such as mechanical stimulation, interaction with lipids or endogenous regulators, intra- or extracellular pH, and phosphorylation, while their function can be finely tuned by chemical compounds. In the latter category, some drug-channel interactions can lead to side effects or have clinical action, while identifying novel chemical modulators of K2Ps is an area of intense research. Due to their cellular and therapeutic importance, much attention was turned to these channels in recent years and several experimental approaches have pinpointed the molecular determinants of K2P chemical modulation. Given their unique structural features and properties, chemical modulators act on K2P channels in multiple and diverse ways. In this review, the particularities of K2P modulation by chemical compounds, such as binding modality, affinity, or position, are identified, synthesized, and linked to structural and functional properties in order to refer to how activators and blockers modify channel function and vice versa, focusing on specificity related to protein structure (and its modification) and cross-linking information among different subfamilies.
Collapse
Affiliation(s)
- Daniel Şterbuleac
- Doctoral School of Biology, Faculty of Biology, "Alexandru Ioan Cuza" University of Iasi, Iasi, Romania
| |
Collapse
|
34
|
Tian F, Qiu Y, Lan X, Li M, Yang H, Gao Z. A Small-Molecule Compound Selectively Activates K2P Channel TASK-3 by Acting at Two Distant Clusters of Residues. Mol Pharmacol 2019; 96:26-35. [DOI: 10.1124/mol.118.115303] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/17/2019] [Indexed: 11/22/2022] Open
|
35
|
Ben Soussia I, El Mouridi S, Kang D, Leclercq-Blondel A, Khoubza L, Tardy P, Zariohi N, Gendrel M, Lesage F, Kim EJ, Bichet D, Andrini O, Boulin T. Mutation of a single residue promotes gating of vertebrate and invertebrate two-pore domain potassium channels. Nat Commun 2019; 10:787. [PMID: 30770809 PMCID: PMC6377628 DOI: 10.1038/s41467-019-08710-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 01/23/2019] [Indexed: 01/28/2023] Open
Abstract
Mutations that modulate the activity of ion channels are essential tools to understand the biophysical determinants that control their gating. Here, we reveal the conserved role played by a single amino acid position (TM2.6) located in the second transmembrane domain of two-pore domain potassium (K2P) channels. Mutations of TM2.6 to aspartate or asparagine increase channel activity for all vertebrate K2P channels. Using two-electrode voltage-clamp and single-channel recording techniques, we find that mutation of TM2.6 promotes channel gating via the selectivity filter gate and increases single channel open probability. Furthermore, channel gating can be progressively tuned by using different amino acid substitutions. Finally, we show that the role of TM2.6 was conserved during evolution by rationally designing gain-of-function mutations in four Caenorhabditis elegans K2P channels using CRISPR/Cas9 gene editing. This study thus describes a simple and powerful strategy to systematically manipulate the activity of an entire family of potassium channels. Mutations that modulate the activity of ion channels are essential tools to understand the biophysical determinants that control their gating. Here authors reveal the role played by a single residue in the second transmembrane domain of vertebrate and invertebrate two-pore domain potassium channels.
Collapse
Affiliation(s)
- Ismail Ben Soussia
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Sonia El Mouridi
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Dawon Kang
- Department of Physiology, College of Medicine and Institute of Health Sciences, Gyeongsang National University, Jinju, 52727, South Korea
| | - Alice Leclercq-Blondel
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Lamyaa Khoubza
- Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, CNRS UMR 7275, Université de Nice Sophia Antipolis, Valbonne, 06560, France
| | - Philippe Tardy
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Nora Zariohi
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Marie Gendrel
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France
| | - Florian Lesage
- Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, CNRS UMR 7275, Université de Nice Sophia Antipolis, Valbonne, 06560, France
| | - Eun-Jin Kim
- Department of Physiology, College of Medicine and Institute of Health Sciences, Gyeongsang National University, Jinju, 52727, South Korea
| | - Delphine Bichet
- Institut de Pharmacologie Moléculaire et Cellulaire, LabEx ICST, CNRS UMR 7275, Université de Nice Sophia Antipolis, Valbonne, 06560, France
| | - Olga Andrini
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France.
| | - Thomas Boulin
- Institut NeuroMyoGène, Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U1217, Lyon, 69008, France.
| |
Collapse
|
36
|
Pope L, Arrigoni C, Lou H, Bryant C, Gallardo-Godoy A, Renslo AR, Minor DL. Protein and Chemical Determinants of BL-1249 Action and Selectivity for K 2P Channels. ACS Chem Neurosci 2018; 9:3153-3165. [PMID: 30089357 PMCID: PMC6302903 DOI: 10.1021/acschemneuro.8b00337] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
K2P potassium channels generate leak currents that stabilize the resting membrane potential of excitable cells. Various K2P channels are implicated in pain, ischemia, depression, migraine, and anesthetic responses, making this family an attractive target for small molecule modulator development efforts. BL-1249, a compound from the fenamate class of nonsteroidal anti-inflammatory drugs is known to activate K2P2.1(TREK-1), the founding member of the thermo- and mechanosensitive TREK subfamily; however, its mechanism of action and effects on other K2P channels are not well-defined. Here, we demonstrate that BL-1249 extracellular application activates all TREK subfamily members but has no effect on other K2P subfamilies. Patch clamp experiments demonstrate that, similar to the diverse range of other chemical and physical TREK subfamily gating cues, BL-1249 stimulates the selectivity filter "C-type" gate that controls K2P function. BL-1249 displays selectivity among the TREK subfamily, activating K2P2.1(TREK-1) and K2P10.1(TREK-2) ∼10-fold more potently than K2P4.1(TRAAK). Investigation of mutants and K2P2.1(TREK-1)/K2P4.1(TRAAK) chimeras highlight the key roles of the C-terminal tail in BL-1249 action and identify the M2/M3 transmembrane helix interface as a key site of BL-1249 selectivity. Synthesis and characterization of a set of BL-1249 analogs demonstrates that both the tetrazole and opposing tetralin moieties are critical for function, whereas the conformational mobility between the two ring systems impacts selectivity. Together, our findings underscore the landscape of modes by which small molecules can affect K2P channels and provide crucial information for the development of better and more selective K2P modulators of the TREK subfamily.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Daniel L. Minor
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
| |
Collapse
|
37
|
Vitali V, Jozefkowicz C, Canessa Fortuna A, Soto G, González Flecha FL, Alleva K. Cooperativity in proton sensing by PIP aquaporins. FEBS J 2018; 286:991-1002. [PMID: 30430736 DOI: 10.1111/febs.14701] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 11/05/2018] [Accepted: 11/13/2018] [Indexed: 11/28/2022]
Abstract
One of the most intriguing properties of plasma membrane intrinsic protein (PIP) aquaporins (AQPs) is their ability to modulate water transport by sensing different levels of intracellular pH through the assembly of homo- and heterotetrameric molecular species in the plasma membrane. In this work, using a phenomenological modeling approach, we demonstrate that cooperativity in PIP biological response cannot be directly attributed to a cooperative proton binding, as it is usually considered, since it could also be the consequence of a cooperative conformation transition between open and closed states of the channel. Moreover, our results show that, when mixed populations of homo- and heterotetrameric PIP channels are coexpressed in the plasma membrane of the same cell, the observed decrease in the degree of positive cooperativity would result from the simultaneous presence of molecular species with different levels of proton sensing. Indeed, the random mixing between different PIP paralogues as subunits in a single tetramer, plus the possibility of mixed populations of homo- and heterotetrameric PIP channels widen the spectrum of cooperative responses of a cell membrane. Our approach offers a deep understanding of cooperative transport of AQP channels, as members of a multiprotein family where the relevant proton binding sites of each member have not been clearly elucidated yet.
Collapse
Affiliation(s)
- Victoria Vitali
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológica (IQUIFIB), Argentina.,Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Fisicomatemática, Argentina
| | - Cintia Jozefkowicz
- Instituto Nacional de Tecnología Agropecuaria, INTA, Castelar, Argentina.,CONICET, Buenos Aires, Argentina
| | - Agustina Canessa Fortuna
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológica (IQUIFIB), Argentina.,Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Fisicomatemática, Argentina
| | - Gabriela Soto
- Instituto Nacional de Tecnología Agropecuaria, INTA, Castelar, Argentina.,CONICET, Buenos Aires, Argentina
| | - F Luis González Flecha
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológica (IQUIFIB), Argentina
| | - Karina Alleva
- Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisicoquímica Biológica (IQUIFIB), Argentina.,Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Fisicomatemática, Argentina
| |
Collapse
|
38
|
Nedumaran B, Pineda RH, Rudra P, Lee S, Malykhina AP. Association of genetic polymorphisms in the pore domains of mechano-gated TREK-1 channel with overactive lower urinary tract symptoms in humans. Neurourol Urodyn 2018; 38:144-150. [PMID: 30350878 DOI: 10.1002/nau.23862] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 09/03/2018] [Indexed: 12/12/2022]
Abstract
AIMS Mechanosensitivity of the urinary bladder is regulated by many factors including mechano-gated two-pore domain (K2 P, KCNK) potassium channels. TWIK-related K+ channel, TREK-1, is a predominantly expressed member of K2 P channel family in the human detrusor, and its expression and function are diminished in patients with overactive lower urinary tract symptoms (LUTS). The changes in channel activity may result from spontaneously occurring gene mutations. The aim of this study was to compare single nucleotide polymorphisms (SNPs) in TREK-1 channel between patients with LUTS and healthy donors. METHODS Six SNPs (rs370266806, rs373919966, rs758937019, rs769301539, rs772497750, and rs775158737) in two pore domains of human TREK-1 gene were analyzed using TaqMan SNP genotyping assay with manufacturer-designed primers and allele-specific probes. The screening was done in control bladders and detrusor specimens from patients with overactive LUTS. Statistical analyses were performed using R, Fisher's exact test and Hardy-Weinberg Equilibrium. RESULTS Six SNPs in two pore domains of the human TREK-1 gene were analyzed in human bladder specimens. The frequencies of rs758937019-CT genotype (P = 0.0016) and rs758937019-T allele (P = 0.0022) were significantly higher in the group with overactive LUTS. There was no significant association of rs775158737-GA genotype and rs775158737-A allele with the overactive LUTS, though they were present only in the overactive LUTS group. CONCLUSIONS Our results provide evidence that altered expression and function of TREK-1 channel in patients with overactive LUTS could be due to genetic polymorphisms in the pore domains of TREK-1 channel (rs758937019).
Collapse
Affiliation(s)
- Balachandar Nedumaran
- Division of Urology, Department of Surgery, University of Colorado Denver, Aurora, Colorado.,Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado Denver, Aurora, Colorado
| | - Ricardo H Pineda
- Division of Urology, Department of Surgery, University of Colorado Denver, Aurora, Colorado
| | - Pratyaydipta Rudra
- Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Denver, Aurora, Colorado
| | - Sanghee Lee
- Department of Urology, University of California San Diego, La Jolla, California
| | - Anna P Malykhina
- Division of Urology, Department of Surgery, University of Colorado Denver, Aurora, Colorado
| |
Collapse
|
39
|
Soussia IB, Choveau FS, Blin S, Kim EJ, Feliciangeli S, Chatelain FC, Kang D, Bichet D, Lesage F. Antagonistic Effect of a Cytoplasmic Domain on the Basal Activity of Polymodal Potassium Channels. Front Mol Neurosci 2018; 11:301. [PMID: 30233308 PMCID: PMC6131555 DOI: 10.3389/fnmol.2018.00301] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 08/09/2018] [Indexed: 02/06/2023] Open
Abstract
TREK/TRAAK channels are polymodal K+ channels that convert very diverse stimuli, including bioactive lipids, mechanical stretch and temperature, into electrical signals. The nature of the structural changes that regulate their activity remains an open question. Here, we show that a cytoplasmic domain (the proximal C-ter domain, pCt) exerts antagonistic effects in TREK1 and TRAAK. In basal conditions, pCt favors activity in TREK1 whereas it impairs TRAAK activity. Using the conformation-dependent binding of fluoxetine, we show that TREK1 and TRAAK conformations at rest are different, and under the influence of pCt. Finally, we show that depleting PIP2 in live cells has a more pronounced inhibitory effect on TREK1 than on TRAAK. This differential regulation of TREK1 and TRAAK is related to a previously unrecognized PIP2-binding site (R329, R330, and R331) present within TREK1 pCt, but not in TRAAK pCt. Collectively, these new data point out pCt as a major regulatory domain of these channels and suggest that the binding of PIP2 to the pCt of TREK1 results in the stabilization of the conductive conformation in basal conditions.
Collapse
Affiliation(s)
- Ismail Ben Soussia
- Université Côte d'Azur, INSERM, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Labex ICST, Valbonne, France
| | - Frank S Choveau
- Université Côte d'Azur, INSERM, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Labex ICST, Valbonne, France
| | - Sandy Blin
- Université Côte d'Azur, INSERM, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Labex ICST, Valbonne, France
| | - Eun-Jin Kim
- Department of Physiology, College of Medicine, Institute of Health Sciences, Gyeongsang National University, Jinju, South Korea
| | - Sylvain Feliciangeli
- Université Côte d'Azur, INSERM, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Labex ICST, Valbonne, France
| | - Franck C Chatelain
- Université Côte d'Azur, INSERM, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Labex ICST, Valbonne, France
| | - Dawon Kang
- Department of Physiology, College of Medicine, Institute of Health Sciences, Gyeongsang National University, Jinju, South Korea
| | - Delphine Bichet
- Université Côte d'Azur, INSERM, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Labex ICST, Valbonne, France
| | - Florian Lesage
- Université Côte d'Azur, INSERM, Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, Labex ICST, Valbonne, France
| |
Collapse
|
40
|
Lengyel M, Czirják G, Enyedi P. TRESK background potassium channel is not gated at the helix bundle crossing near the cytoplasmic end of the pore. PLoS One 2018; 13:e0197622. [PMID: 29763475 PMCID: PMC5953468 DOI: 10.1371/journal.pone.0197622] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 05/05/2018] [Indexed: 12/20/2022] Open
Abstract
Two-pore domain K+ channels (K2P) are responsible for background K+ currents and regulate the resting membrane potential and cellular excitability. Their activity is controlled by a large variety of physicochemical factors and intracellular signaling pathways. The majority of these effects converge on the intracellular C-terminus of the channels, resulting in the modification of the gating at the selectivity filter. Another gating mechanism, the activation gate at the helix bundle crossing is also well documented in other K+ channel families, however, it remains uncertain whether this type of gating is functional in K2P channels. The regulation of TWIK-related spinal cord K+ channel (TRESK) is different from the other K2P channels. Regulatory factors acting via the C-terminus are not known, instead channel activity is modified by the phosphorylation/dephosphorylation of the unusually long intracellular loop between the 2nd and 3rd transmembrane segments. These unique structural elements of the regulation lead us to examine channel gating at the bundle crossing region. Ba2+ was applied to the intracellular side of excised membrane patches and the characteristics of the channel block were determined. We compared the kinetics of the development of Ba2+ block when the channels were phosphorylated (inhibited) or dephosphorylated (activated) and also in different mutants mimicking the two functional states. Neither the phosphorylation/dephosphorylation nor the point mutations influenced the development of Ba2+ block, suggesting that the conformational changes of the bundle crossing region do not contribute to the phosphorylation-dependent gating of TRESK.
Collapse
Affiliation(s)
- Miklós Lengyel
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Gábor Czirják
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Péter Enyedi
- Department of Physiology, Semmelweis University, Budapest, Hungary
- * E-mail:
| |
Collapse
|
41
|
Hoffstaetter LJ, Bagriantsev SN, Gracheva EO. TRPs et al.: a molecular toolkit for thermosensory adaptations. Pflugers Arch 2018; 470:745-759. [PMID: 29484488 PMCID: PMC5945325 DOI: 10.1007/s00424-018-2120-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/03/2018] [Accepted: 02/05/2018] [Indexed: 12/19/2022]
Abstract
The ability to sense temperature is crucial for the survival of an organism. Temperature influences all biological operations, from rates of metabolic reactions to protein folding, and broad behavioral functions, from feeding to breeding, and other seasonal activities. The evolution of specialized thermosensory adaptations has enabled animals to inhabit extreme temperature niches and to perform specific temperature-dependent behaviors. The function of sensory neurons depends on the participation of various types of ion channels. Each of the channels involved in neuronal excitability, whether through the generation of receptor potential, action potential, or the maintenance of the resting potential have temperature-dependent properties that can tune the neuron's response to temperature stimuli. Since the function of all proteins is affected by temperature, animals need adaptations not only for detecting different temperatures, but also for maintaining sensory ability at different temperatures. A full understanding of the molecular mechanism of thermosensation requires an investigation of all channel types at each step of thermosensory transduction. A fruitful avenue of investigation into how different molecules can contribute to the fine-tuning of temperature sensitivity is to study the specialized adaptations of various species. Given the diversity of molecular participants at each stage of sensory transduction, animals have a toolkit of channels at their disposal to adapt their thermosensitivity to their particular habitats or behavioral circumstances.
Collapse
Affiliation(s)
- Lydia J Hoffstaetter
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8026, USA
- Department of Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8026, USA
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8026, USA
| | - Sviatoslav N Bagriantsev
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8026, USA
| | - Elena O Gracheva
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8026, USA.
- Department of Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8026, USA.
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, 333 Cedar Street, New Haven, CT, 06520-8026, USA.
| |
Collapse
|
42
|
Global versus local mechanisms of temperature sensing in ion channels. Pflugers Arch 2018; 470:733-744. [PMID: 29340775 DOI: 10.1007/s00424-017-2102-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 12/15/2017] [Accepted: 12/19/2017] [Indexed: 02/07/2023]
Abstract
Ion channels turn diverse types of inputs, ranging from neurotransmitters to physical forces, into electrical signals. Channel responses to ligands generally rely on binding to discrete sensor domains that are coupled to the portion of the channel responsible for ion permeation. By contrast, sensing physical cues such as voltage, pressure, and temperature arises from more varied mechanisms. Voltage is commonly sensed by a local, domain-based strategy, whereas the predominant paradigm for pressure sensing employs a global response in channel structure to membrane tension changes. Temperature sensing has been the most challenging response to understand and whether discrete sensor domains exist for pressure and temperature has been the subject of much investigation and debate. Recent exciting advances have uncovered discrete sensor modules for pressure and temperature in force-sensitive and thermal-sensitive ion channels, respectively. In particular, characterization of bacterial voltage-gated sodium channel (BacNaV) thermal responses has identified a coiled-coil thermosensor that controls channel function through a temperature-dependent unfolding event. This coiled-coil thermosensor blueprint recurs in other temperature sensitive ion channels and thermosensitive proteins. Together with the identification of ion channel pressure sensing domains, these examples demonstrate that "local" domain-based solutions for sensing force and temperature exist and highlight the diversity of both global and local strategies that channels use to sense physical inputs. The modular nature of these newly discovered physical signal sensors provides opportunities to engineer novel pressure-sensitive and thermosensitive proteins and raises new questions about how such modular sensors may have evolved and empowered ion channel pores with new sensibilities.
Collapse
|
43
|
McClenaghan C, Schewe M, Aryal P, Carpenter EP, Baukrowitz T, Tucker SJ. Polymodal activation of the TREK-2 K2P channel produces structurally distinct open states. J Gen Physiol 2017; 147:497-505. [PMID: 27241700 PMCID: PMC4886281 DOI: 10.1085/jgp.201611601] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 05/09/2016] [Indexed: 01/08/2023] Open
Abstract
TREK channels, which are gated open by a wide range of stimuli, exist in at least two conformations known as “up” and “down.” McClenaghan et al. show that the channel can be open in both of these conformations and that gating is primarily achieved by the channel’s selectivity filter. The TREK subfamily of two-pore domain (K2P) K+ channels exhibit polymodal gating by a wide range of physical and chemical stimuli. Crystal structures now exist for these channels in two main states referred to as the “up” and “down” conformations. However, recent studies have resulted in contradictory and mutually exclusive conclusions about the functional (i.e., conductive) status of these two conformations. To address this problem, we have used the state-dependent TREK-2 inhibitor norfluoxetine that can only bind to the down state, thereby allowing us to distinguish between these two conformations when activated by different stimuli. Our results reconcile these previously contradictory gating models by demonstrating that activation by pressure, temperature, voltage, and pH produce more than one structurally distinct open state and reveal that channel activation does not simply involve switching between the up and down conformations. These results also highlight the diversity of structural mechanisms that K2P channels use to integrate polymodal gating signals.
Collapse
Affiliation(s)
- Conor McClenaghan
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, England, UK OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PU, England, UK
| | - Marcus Schewe
- Department of Physiology, University of Kiel, 24118 Kiel, Germany
| | - Prafulla Aryal
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, England, UK OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PU, England, UK
| | - Elisabeth P Carpenter
- OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PU, England, UK Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, England, UK
| | | | - Stephen J Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, England, UK OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PU, England, UK
| |
Collapse
|
44
|
Woo J, Jun YK, Zhang YH, Nam JH, Shin DH, Kim SJ. Identification of critical amino acids in the proximal C-terminal of TREK-2 K + channel for activation by acidic pH i and ATP-dependent inhibition. Pflugers Arch 2017; 470:327-337. [PMID: 28988317 DOI: 10.1007/s00424-017-2072-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/30/2017] [Accepted: 09/19/2017] [Indexed: 02/06/2023]
Abstract
TWIK-related two-pore domain K+ channels (TREKs) are regulated by intracellular pH (pHi) and Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). Previously, Glu306 in proximal C-terminal (pCt) of mouse TREK-1 was identified as the pHi-sensing residue. The direction of PI(4,5)P2 sensitivity is controversial, and we have recently shown that TREKs are inhibited by intracellular ATP via endogenous PI(4,5)P2 formation. Here we investigate the anionic and cationic residues of pCt for the pHi and ATP-sensitivity in human TREK-2 (hTREK-2). In inside-out patch clamp recordings (ITREK-2,i-o), acidic pHi-induced activation was absent in E332A and was partly attenuated in E335A. Neutralization of cationic Lys (K330A) also eliminated the acidic pHi sensitivity of ITREK-2,i-o. Unlike the inhibition of wild-type (WT) ITREK-2,i-o by intracellular ATP, neither E332A nor K330A was sensitive to ATP. Nevertheless, exogenous PI(4,5)P2 (10 μM) abolished ITREK-2 i-o in all the above mutants as well as in WT, indicating unspecific inhibition by exogenous PI(4,5)P2. In whole-cell recordings of TREK-2 (ITREK-2,w-c), K330A and E332A showed higher or fully active basal activity, showing attenuated or insignificant activation by 2-APB, arachidonic acid, or acidic pHe 6.9. ITREK-1,w-c of WT is largely suppressed by pHe 6.9, and the inhibition is slightly attenuated in K312A and E315A. The results show concerted roles of the oppositely charged Lys and Glu in pCt for the ATP-dependent low basal activity and pHi sensitivity.
Collapse
Affiliation(s)
- Joohan Woo
- Department of Physiology, College of Medicine, Seoul National University, 103 Daehak-ro, Jongno-Gu, Seoul, 03080, Korea
| | - Young Keul Jun
- Department of Physiology, College of Medicine, Seoul National University, 103 Daehak-ro, Jongno-Gu, Seoul, 03080, Korea
| | - Yin-Hua Zhang
- Department of Physiology, College of Medicine, Seoul National University, 103 Daehak-ro, Jongno-Gu, Seoul, 03080, Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea
| | - Dong Hoon Shin
- Department of Pharmacology, Yonsei University, Seoul, Korea.
| | - Sung Joon Kim
- Department of Physiology, College of Medicine, Seoul National University, 103 Daehak-ro, Jongno-Gu, Seoul, 03080, Korea.
| |
Collapse
|
45
|
Lolicato M, Arrigoni C, Mori T, Sekioka Y, Bryant C, Clark KA, Minor DL. K 2P2.1 (TREK-1)-activator complexes reveal a cryptic selectivity filter binding site. Nature 2017; 547:364-368. [PMID: 28693035 PMCID: PMC5778891 DOI: 10.1038/nature22988] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 05/12/2017] [Indexed: 12/11/2022]
Abstract
Polymodal K2P (KCNK) thermo- and mechanosensitive TREK1 potassium channels, generate ‘leak’ currents that regulate neuronal excitability, respond to lipids, temperature, and mechanical stretch, and influence pain, temperature perception, and anesthetic responses1–3. These dimeric voltage-gated ion channel (VGIC) superfamily members have a unique topology comprising two pore forming regions per subunit4–6. Contrasting other potassium channels, K2Ps use a selectivity filter ‘C-type’ gate7–10 as the principal gating site. Despite recent advances3,11,12, K2Ps suffer from a poor pharmacologic profile limiting mechanistic and biological studies. Here, we describe a new small molecule TREK activator class that directly stimulates the C-type gate by acting as molecular wedges that restrict interdomain interface movement behind the selectivity filter. Structures of K2P2.1(TREK-1) alone with two selective K2P2.1(TREK-1) and K2P10.1(TREK-2) activators, an N-aryl-sulfonamide, ML335, and a thiophene-carboxamide, ML402, define a cryptic binding pocket unlike other ion channel small molecule binding sites and, together with functional studies, identify a cation-π interaction that controls selectivity. Together, our data unveil a previously unknown, druggable K2P site that stabilizes the C-type gate ‘leak mode’ and provide direct evidence for K2P selectivity filter gating.
Collapse
Affiliation(s)
- Marco Lolicato
- Cardiovascular Research Institute, University of California, San Francisco, California 941158-9001, USA
| | - Cristina Arrigoni
- Cardiovascular Research Institute, University of California, San Francisco, California 941158-9001, USA
| | - Takahiro Mori
- Ono Pharmaceutical Co. Ltd, Mishima-Gun, Osaka 618-8585, Japan
| | - Yoko Sekioka
- Ono Pharmaceutical Co. Ltd, Mishima-Gun, Osaka 618-8585, Japan
| | - Clifford Bryant
- Small Molecule Discovery Center, University of California, San Francisco, California 93858-2330, USA
| | - Kimberly A Clark
- Cardiovascular Research Institute, University of California, San Francisco, California 941158-9001, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, California 941158-9001, USA.,Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, California 941158-9001, USA.,California Institute for Quantitative Biomedical Research, University of California, San Francisco, California 941158-9001, USA.,Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, California 941158-9001, USA.,Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| |
Collapse
|
46
|
Dickerson MT, Vierra NC, Milian SC, Dadi PK, Jacobson DA. Osteopontin activates the diabetes-associated potassium channel TALK-1 in pancreatic β-cells. PLoS One 2017; 12:e0175069. [PMID: 28403169 PMCID: PMC5389796 DOI: 10.1371/journal.pone.0175069] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 03/20/2017] [Indexed: 12/17/2022] Open
Abstract
Glucose-stimulated insulin secretion (GSIS) relies on β-cell Ca2+ influx, which is modulated by the two-pore-domain K+ (K2P) channel, TALK-1. A gain-of-function polymorphism in KCNK16, the gene encoding TALK-1, increases risk for developing type-2 diabetes. While TALK-1 serves an important role in modulating GSIS, the regulatory mechanism(s) that control β-cell TALK-1 channels are unknown. Therefore, we employed a membrane-specific yeast two-hybrid (MYTH) assay to identify TALK-1-interacting proteins in human islets, which will assist in determining signaling modalities that modulate TALK-1 function. Twenty-one proteins from a human islet cDNA library interacted with TALK-1. Some of these interactions increased TALK-1 activity, including intracellular osteopontin (iOPN). Intracellular OPN is highly expressed in β-cells and is upregulated under pre-diabetic conditions to help maintain normal β-cell function; however, the functional role of iOPN in β-cells is poorly understood. We found that iOPN colocalized with TALK-1 in pancreatic sections and coimmunoprecipitated with human islet TALK-1 channels. As human β-cells express two K+ channel-forming variants of TALK-1, regulation of these TALK-1 variants by iOPN was assessed. At physiological voltages iOPN activated TALK-1 transcript variant 3 channels but not TALK-1 transcript variant 2 channels. Activation of TALK-1 channels by iOPN also hyperpolarized resting membrane potential (Vm) in HEK293 cells and in primary mouse β-cells. Intracellular OPN was also knocked down in β-cells to test its effect on β-cell TALK-1 channel activity. Reducing β-cell iOPN significantly decreased TALK-1 K+ currents and increased glucose-stimulated Ca2+ influx. Importantly, iOPN did not affect the function of other K2P channels or alter Ca2+ influx into TALK-1 deficient β-cells. These results reveal the first protein interactions with the TALK-1 channel and found that an interaction with iOPN increased β-cell TALK-1 K+ currents. The TALK-1/iOPN complex caused Vm hyperpolarization and reduced β-cell glucose-stimulated Ca2+ influx, which is predicted to inhibit GSIS.
Collapse
Affiliation(s)
- Matthew T. Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Nicholas C. Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sarah C. Milian
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Prasanna K. Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - David A. Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| |
Collapse
|
47
|
Rungta RL, Osmanski BF, Boido D, Tanter M, Charpak S. Light controls cerebral blood flow in naive animals. Nat Commun 2017; 8:14191. [PMID: 28139643 PMCID: PMC5290324 DOI: 10.1038/ncomms14191] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 12/07/2016] [Indexed: 01/05/2023] Open
Abstract
Optogenetics is increasingly used to map brain activation using techniques that rely on functional hyperaemia, such as opto-fMRI. Here we test whether light stimulation protocols similar to those commonly used in opto-fMRI or to study neurovascular coupling modulate blood flow in mice that do not express light sensitive proteins. Combining two-photon laser scanning microscopy and ultrafast functional ultrasound imaging, we report that in the naive mouse brain, light per se causes a calcium decrease in arteriolar smooth muscle cells, leading to pronounced vasodilation, without excitation of neurons and astrocytes. This photodilation is reversible, reproducible and energy-dependent, appearing at about 0.5 mJ. These results impose careful consideration on the use of photo-activation in studies involving blood flow regulation, as well as in studies requiring prolonged and repetitive stimulations to correct cellular defects in pathological models. They also suggest that light could be used to locally increase blood flow in a controlled fashion. Combination of optogenetics and BOLD fMRI is routinely used to map neuronal activity upon photostimulation. Here the authors show that light, shone at intensities used in optogenetic studies, dilates vessels and increases blood flow independently of exogenous light-sensitive proteins in the mouse brain.
Collapse
Affiliation(s)
- Ravi L Rungta
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Bruno-Félix Osmanski
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Davide Boido
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| | - Mickael Tanter
- Institut Langevin, Espci Paris, CNRS UMR 7587, INSERM U979, PSL Research University, 17 rue Moreau, Paris 75012, France
| | - Serge Charpak
- INSERM U1128, Laboratory of Neurophysiology and New Microscopies, Université Paris Descartes, Paris 75006, France
| |
Collapse
|
48
|
Ezquerra-Romano I, Ezquerra A. Highway to thermosensation: a traced review, from the proteins to the brain. Rev Neurosci 2017; 28:45-57. [PMID: 27754972 DOI: 10.1515/revneuro-2016-0039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 08/07/2016] [Indexed: 01/09/2023]
Abstract
Temperature maintenance and detection are essential for the survival and perpetuation of any species. This review is focused on thermosensation; thus a detailed and traced explanation of the anatomical and physiological characteristics of each component of this sensation is given. First, the proteins that react to temperature changes are identified; next, the nature of the neurons involved in thermosensation is described; and then, the pathways from the skin through the spinal cord to the brain are outlined. Finally, the areas of the brain and their interconnections where thermoperception arises are explained. Transduction of the external and internal temperature information is essentially mediated by the transient receptor potential ion channels (TRPs). These proteins are embedded in the neurons' membrane and they hyper- or de-polarize neurons in function of the intrinsic voltage and the temperature changes. There are distinct TRP sensors for different temperature ranges. Interestingly, the primary afferent neurons have either cold or hot receptors, so they are dedicated separately to cold or hot sensation. The information is transmitted by different pathways from the skin to the brain, where it either remains separated or is integrated to generate a response. It seems that both the determination of how thermoperception is produced and how we interact with the world are dependent on the particular arrangement and nature of the components, the way of transduction of information and the communication between these elements.
Collapse
|
49
|
Cox CD, Bavi N, Martinac B. Origin of the Force: The Force-From-Lipids Principle Applied to Piezo Channels. CURRENT TOPICS IN MEMBRANES 2016; 79:59-96. [PMID: 28728824 DOI: 10.1016/bs.ctm.2016.09.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Piezo channels are a ubiquitously expressed, principal type of molecular force sensor in eukaryotes. They enable cells to decode a myriad of physical stimuli and are essential components of numerous mechanosensory processes. Central to their physiological role is the ability to change conformation in response to mechanical force. Here we discuss the evolutionary origin of Piezo in relation to other MS channels in addition to the force that gates Piezo channels. In particular, we discuss whether Piezo channels are inherently mechanosensitive in accordance with the force-from-lipid paradigm which has been firmly established for bacterial MS channels and two-pore domain K+ (K2P) channels. We also discuss the evidence supporting a reliance on or direct interaction with structural scaffold proteins of the cytoskeleton and extracellular matrix according to the force-from-filament principle. In doing so, we explain the false dichotomy that these distinctions represent. We also discuss the possible unifying models that shed light on channel mechanosensitivity at the molecular level.
Collapse
Affiliation(s)
- C D Cox
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia; University of New South Wales, Darlinghurst, NSW, Australia
| | - N Bavi
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia; University of New South Wales, Darlinghurst, NSW, Australia
| | - B Martinac
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia; University of New South Wales, Darlinghurst, NSW, Australia
| |
Collapse
|
50
|
Exploring functional roles of TRPV1 intracellular domains with unstructured peptide-insertion screening. Sci Rep 2016; 6:33827. [PMID: 27666400 PMCID: PMC5035920 DOI: 10.1038/srep33827] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 08/30/2016] [Indexed: 01/23/2023] Open
Abstract
TRPV1 is a polymodal nociceptor for diverse physical and chemical stimuli that interact with different parts of the channel protein. Recent cryo-EM studies revealed detailed channel structures, opening the door for mapping structural elements mediating activation by each stimulus. Towards this goal, here we have combined unstructured peptide-insertion screening (UPS) with electrophysiological and fluorescence recordings to explore structural and functional roles of the intracellular regions of TRPV1 in mediating various activation stimuli. We found that most of the tightly packed protein regions did not tolerate structural perturbation by UPS when tested, indicating that structural integrity of the intracellular region is critical. In agreement with previous reports, Ca2+-dependent desensitization is strongly dependent on both intracellular N- and C-terminal domains; insertions of an unstructured peptide between these domains and the transmembrane core domain nearly eliminated Ca2+-dependent desensitization. In contrast, channel activations by capsaicin, low pH, divalent cations, and even heat are mostly intact in mutant channels containing the same insertions. These observations suggest that the transmembrane core domain of TRPV1, but not the intracellular domains, is responsible for sensing these stimuli.
Collapse
|