1
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Veale EL, Golluscio A, Grand K, Graham JM, Mathie A. A KCNB1 gain of function variant causes developmental delay and speech apraxia but not seizures. Front Pharmacol 2022; 13:1093313. [PMID: 36618935 PMCID: PMC9810754 DOI: 10.3389/fphar.2022.1093313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Objective: Numerous pathogenic variants in KCNB1, which encodes the voltage-gated potassium channel, KV2.1, are linked to developmental and epileptic encephalopathies and associated with loss-of-function, -regulation, and -expression of the channel. Here we describe a novel de novo variant (P17T) occurring in the KV2.1 channel that is associated with a gain-of-function (GoF), with altered steady-state inactivation and reduced sensitivity to the selective toxin, guanxitoxin-1E and is clinically associated with neurodevelopmental disorders, without seizures. Methods: The autosomal dominant variant was identified using whole exome sequencing (WES). The functional effects of the KCNB1 variant on the encoded KV2.1 channel were investigated using whole-cell patch-clamp recordings. Results: We identified a de novo missense variant in the coding region of the KCNB1 gene, c.49C>A which encodes a p.P17T mutation in the N-terminus of the voltage-gated, KV2.1 potassium channel. Electrophysiological studies measuring the impact of the variant on the functional properties of the channel, identified a gain of current, rightward shifts in the steady-state inactivation curve and reduced sensitivity to the blocker, guanxitoxin-1E. Interpretation: The clinical evaluation of this KCNB1 mutation describes a novel variant that is associated with global developmental delays, mild hypotonia and joint laxity, but without seizures. Most of the phenotypic features described are reported for other variants of the KCNB1 gene. However, the absence of early-onset epileptic disorders is a much less common occurrence. This lack of seizure activity may be because other variants reported have resulted in loss-of-function of the encoded KV2.1 potassium channel, whereas this variant causes a gain-of-function.
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Affiliation(s)
- Emma L. Veale
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom
| | - Alessia Golluscio
- Medway School of Pharmacy, University of Kent and University of Greenwich, Chatham Maritime, United Kingdom
| | - Katheryn Grand
- Department of Pediatrics, Harbor-UCLA Medical Center, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - John M. Graham
- Department of Pediatrics, Harbor-UCLA Medical Center, Cedars-Sinai Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States,*Correspondence: Alistair Mathie, ; John M. Graham Jr.,
| | - 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,*Correspondence: Alistair Mathie, ; John M. Graham Jr.,
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2
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McCoull D, Veale EL, Walsh Y, Byrom L, Avkiran T, Large JM, Vaitone E, Gaffey F, Jerman J, Mathie A, Wright PD. Aprepitant is a novel, selective activator of the K2P channel TRAAK. Biochem Biophys Res Commun 2021; 588:41-46. [PMID: 34942533 DOI: 10.1016/j.bbrc.2021.12.031] [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: 12/09/2021] [Accepted: 12/12/2021] [Indexed: 11/02/2022]
Abstract
TRAAK (KCNK4, K2P4.1) is a mechanosensitive two-pore domain potassium (K2P) channel. Due to its expression within sensory neurons and genetic link to neuropathic pain it represents a promising potential target for novel analgesics. In common with many other channels in the wider K2P sub-family, there remains a paucity of small molecule pharmacological tools. Specifically, there is a lack of molecules selective for TRAAK over the other members of the TREK subfamily of K2P channels. We developed a thallium flux assay to allow high throughput screening of compounds and facilitate the identification of novel TRAAK activators. Using a library of ∼1200 drug like molecules we identified Aprepitant as a small molecule activator of TRAAK. Aprepitant is an NK-1 antagonist used to treat nausea and vomiting. Close structural analogues of Aprepitant and a range of NK-1 antagonists were also selected or designed for purchase or brief chemical synthesis and screened for their ability to activate TRAAK. Electrophysiology experiments confirmed that Aprepitant activates both the 'long' and 'short' transcript variants of TRAAK. We also demonstrated that Aprepitant is selective and does not activate other members of the K2P superfamily. This work describes the development of a high throughput assay to identify potential TRAAK activators and subsequent identification and confirmation of the novel TRAAK activator Aprepitant. This discovery identifies a useful tool compound which can be used to further probe the function of TRAAK K2P channels.
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Affiliation(s)
- D McCoull
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK.
| | - E L Veale
- Medway School of Pharmacy, University of Greenwich and University of Kent, Anson Building, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Y Walsh
- Medway School of Pharmacy, University of Greenwich and University of Kent, Anson Building, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - L Byrom
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK
| | - T Avkiran
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK
| | - J M Large
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK
| | - E Vaitone
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK
| | - F Gaffey
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK
| | - J Jerman
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK
| | - A Mathie
- Medway School of Pharmacy, University of Greenwich and University of Kent, Anson Building, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK; School of Engineering, Arts, Science and Technology, University of Suffolk, Ipswich, IP4 1QJ, UK
| | - P D Wright
- LifeArc, Accelerator Building, Open Innovation Campus, Stevenage, SG1 2FX, UK
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3
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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4
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García G, Martínez-Rojas VA, Murbartián J. TREK-1 potassium channels participate in acute and long-lasting nociceptive hypersensitivity induced by formalin in rats. Behav Brain Res 2021; 413:113446. [PMID: 34224765 DOI: 10.1016/j.bbr.2021.113446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 06/18/2021] [Accepted: 07/01/2021] [Indexed: 01/06/2023]
Abstract
TREK-1 channels are expressed in small nociceptive dorsal root ganglion (DRG) neurons where they participate in acute inflammatory and neuropathic pain. However, the role of TREK-1 in persistent pain is not well understood. The aim of this study was to investigate the local peripheral and spinal participation of TREK-1 in formalin-induced acute and long-lasting nociceptive hypersensitivity. Local peripheral or intrathecal pre-treatment with spadin, selective blocker of TREK-1, increased acute flinching behavior and secondary mechanical allodynia and hyperalgesia behavior observed 6 days after formalin injection. Local peripheral or intrathecal pre-treatment with BL-1249, selective opener of TREK-1, decreased long-lasting secondary mechanical allodynia and hyperalgesia induced by formalin. Pre-treatment with BL-1249 prevented the pro-nociceptive effect of spadin on acute nociception and long-lasting mechanical allodynia and hyperalgesia in rats. Pre-treatment with two recombinant channels that produce a high TREK-1 current, S300A and S333A (non-phosphorylated state of TREK-1), reduced formalin-induced acute pain and long-lasting mechanical allodynia and hyperalgesia. Besides, post-treatment with S300A, S333A or BL-1249 reversed long-lasting mechanical allodynia and hyperalgesia induced by formalin. Formalin increased TREK-1 expression at 1 and 6 days in DRG and dorsal spinal cord in rats, whereas that it increased c-fos expression at the DRG. Intrathecal repeated transfection of rats with S300A and S333A or injection with BL-1249 reduced formalin-induced enhanced c-fos expression. Data suggest that TREK-1 activity at peripheral and spinal sites reduces neuronal excitability in the process of acute and long-lasting nociception induced by formalin in rats.
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Affiliation(s)
- Guadalupe García
- Departamento de Farmacobiología, Cinvestav, Sede Sur, Mexico City, Mexico.
| | | | - Janet Murbartián
- Departamento de Farmacobiología, Cinvestav, Sede Sur, Mexico City, Mexico.
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5
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Mathie A, Veale EL, Golluscio A, Holden RG, Walsh Y. Pharmacological Approaches to Studying Potassium Channels. Handb Exp Pharmacol 2021; 267:83-111. [PMID: 34195873 DOI: 10.1007/164_2021_502] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this review, we consider the pharmacology of potassium channels from the perspective of these channels as therapeutic targets. Firstly, we describe the three main families of potassium channels in humans and disease states where they are implicated. Secondly, we describe the existing therapeutic agents which act on potassium channels and outline why these channels represent an under-exploited therapeutic target with potential for future drug development. Thirdly, we consider the evidence desired in order to embark on a drug discovery programme targeting a particular potassium channel. We have chosen two "case studies": activators of the two-pore domain potassium (K2P) channel TREK-2 (K2P10.1), for the treatment of pain and inhibitors of the voltage-gated potassium channel KV1.3, for use in autoimmune diseases such as multiple sclerosis. We describe the evidence base to suggest why these are viable therapeutic targets. Finally, we detail the main technical approaches available to characterise the pharmacology of potassium channels and identify novel regulatory compounds. We draw particular attention to the Comprehensive in vitro Proarrhythmia Assay initiative (CiPA, https://cipaproject.org ) project for cardiac safety, as an example of what might be both desirable and possible in the future, for ion channel regulator discovery projects.
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Affiliation(s)
- Alistair Mathie
- Medway School of Pharmacy, University of Kent, Kent, UK. .,Medway School of Pharmacy, University of Greenwich, London, UK. .,School of Engineering, Arts, Science and Technology, University of Suffolk, Ipswich, UK.
| | - Emma L Veale
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
| | - Alessia Golluscio
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
| | - Robyn G Holden
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
| | - Yvonne Walsh
- Medway School of Pharmacy, University of Kent, Kent, UK.,Medway School of Pharmacy, University of Greenwich, London, UK
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6
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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.
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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
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7
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Walsh Y, Leach M, Veale EL, Mathie A. Block of TREK and TRESK K2P channels by lamotrigine and two derivatives sipatrigine and CEN-092. Biochem Biophys Rep 2021; 26:101021. [PMID: 34041373 PMCID: PMC8144350 DOI: 10.1016/j.bbrep.2021.101021] [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: 03/26/2021] [Revised: 04/29/2021] [Accepted: 05/07/2021] [Indexed: 11/30/2022] Open
Abstract
TREK and TRESK K2P channels are widely expressed in the nervous system, particularly in sensory neurons, where they regulate neuronal excitability. In this study, using whole-cell patch-clamp electrophysiology, we characterise the inhibitory effect of the anticonvulsant lamotrigine and two derivatives, sipatrigine and 3,5-diamino-6-(3,5-bistrifluoromethylphenyl)-1,2,4-triazine (CEN-092) on these channels. Sipatrigine was found to be a more effective inhibitor than lamotrigine of TREK-1, TREK-2 and TRESK channels. Sipatrigine was slightly more potent on TREK-1 channels (EC50 = 16 μM) than TRESK (EC50 = 34 μM) whereas lamotrigine was equally effective on TREK-1 and TRESK. Sipatrigine was less effective on a short isoform of TREK-2, suggesting the N terminus of the channel is important for both inhibition and subsequent over-recovery. Inhibition of TREK-1 and TREK-2 channels by sipatrigine was reduced by mutation of a leucine residue associated with the norfluoxetine binding site on these channels (L289A and L320A on TREK-1 and TREK-2, respectively) but these did not affect inhibition by lamotrigine. Inhibition of TRESK by sipatrigine and lamotrigine was attenuated by mutation of bulky phenylalanine residues (F145A and F352A) in the inner pore helix. However, phosphorylation mutations did not alter the effect of sipatrigine. CEN-092 was a more effective inhibitor of TRESK channels than TREK-1 channels. It is concluded that lamotrigine, sipatrigine and CEN-092 are all inhibitors of TREK and TRESK channels but do not greatly discriminate between them. The actions of these compounds may contribute to their current and potential use in the treatment of pain and depression. Lamotrigine blocks TREK and TRESK potassium channels at clinical concentrations. Sipatrigine is more effective than lamotrigine at blocking TREK and TRESK channels. Mutation of norfluoxetine binding site on TREK channels attenuates sipatrigine block. Residues in the inner pore region of TRESK channels regulate sipatrigine block. The novel lamotrigine derivative, CEN-092, blocks TRESK channels.
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Affiliation(s)
- Yvonne Walsh
- Medway School of Pharmacy, University of Kent and University of Greenwich, Central Avenue, Chatham Maritime, ME4 4TB, UK
- University of Greenwich, Central Avenue, Chatham Maritime, ME4 4TB, UK
| | - Michael Leach
- University of Greenwich, Central Avenue, Chatham Maritime, ME4 4TB, UK
| | - Emma L. Veale
- Medway School of Pharmacy, University of Kent and University of Greenwich, Central Avenue, Chatham Maritime, ME4 4TB, UK
| | - Alistair Mathie
- Medway School of Pharmacy, University of Kent and University of Greenwich, Central Avenue, Chatham Maritime, ME4 4TB, UK
- School of Engineering, Arts, Science and Technology, University of Suffolk, Waterfront Building, Neptune Quay, Ipswich, IP4 1QJ, UK
- Corresponding author.Medway School of Pharmacy, University of Kent and University of Greenwich, Central Avenue, Chatham Maritime, ME4 4TB, UK.
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8
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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.
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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.
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9
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Huang L, Xu G, Jiang R, Luo Y, Zuo Y, Liu J. Development of Non-opioid Analgesics Targeting Two-pore Domain Potassium Channels. Curr Neuropharmacol 2021; 20:16-26. [PMID: 33827408 PMCID: PMC9199554 DOI: 10.2174/1570159x19666210407152528] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/14/2021] [Accepted: 03/24/2021] [Indexed: 02/08/2023] Open
Abstract
Two-pore domain potassium (K2P) channels are a diverse family of potassium channels. K2P channels generate background leak potassium currents to regulate cellular excitability and are thereby involved in a wide range of neurological disorders. K2P channels are modulated by a variety of physicochemical factors such as mechanical stretch, temperature, and pH. In the the peripheral nervous system (PNS), K2P channels are widely expressed in nociceptive neurons and play a critical roles in pain perception. In this review, we summarize the recent advances in the pharmacological properties of K2P channels, with a focus on the exogenous small-molecule activators targeting K2P channels. We emphasize the subtype-selectivity, cellular and in vivo pharmacological properties of all the reported small-molecule activators. The key underlying analgesic mechanisms mediated by K2P are also summarized based on the data in the literature from studies using small-molecule activators and genetic knock-out animals. We discuss advantages and limitations of the translational perspectives of K2P in pain medicine and provide outstanding questions for future studies in the end.
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Affiliation(s)
- Lu Huang
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Guangyin Xu
- Department of Physiology and Neurobiology, Institute of Neuroscience, Medical College of Soochow University, Suzhou, 215123, Jiangsu. China
| | - Ruotian Jiang
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Yuncheng Luo
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Yunxia Zuo
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
| | - Jin Liu
- Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610000, Sichuan. China
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10
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Abstract
Heterologous expression of recombinant ion channel subunits in mammalian cell lines allows for characterization of their functional properties and pharmacological regulation. In this chapter, we describe methods for thawing, refreezing, passaging, cell culture, and transfection of tsA201 cells suitable for electrophysiology and imaging experiments. Furthermore, we discuss the strengths and limitations of using these methods.
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11
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McCoull D, Ococks E, Large JM, Tickle DC, Mathie A, Jerman J, Wright PD. A "Target Class" Screen to Identify Activators of Two-Pore Domain Potassium (K2P) Channels. SLAS DISCOVERY 2020; 26:428-438. [PMID: 33375888 PMCID: PMC7900820 DOI: 10.1177/2472555220976126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Two-pore domain potassium (K2P) channels carry background (or leak) potassium
current and play a key role in regulating resting membrane potential and
cellular excitability. Accumulating evidence points to a role for K2Ps in human
pathophysiologies, most notably in pain and migraine, making them attractive
targets for therapeutic intervention. However, there remains a lack of selective
pharmacological tools. The aim of this work was to apply a “target class”
approach to investigate the K2P superfamily and identify novel activators across
all the described subclasses of K2P channels. Target class drug discovery allows
for the leveraging of accumulated knowledge and maximizing synergies across a
family of targets and serves as an additional approach to standard target-based
screening. A common assay platform using baculovirus (BacMam) to transiently
express K2P channels in mammalian cells and a thallium flux assay to determine
channel activity was developed, allowing the simultaneous screening of multiple
targets. Importantly, this system, by allowing precise titration of channel
function, allows optimization to facilitate the identification of activators. A
representative set of channels (THIK-1, TWIK-1, TREK-2, TASK-3, and TASK-2) were
screened against a library of Food and Drug Administration (FDA)-approved
compounds and the LifeArc Index Set. Activators were then analyzed in
concentration–response format across all channels to assess selectivity. Using
the target class approach to investigate the K2P channels has enabled us to
determine which of the K2Ps are amenable to small-molecule activation, de-risk
multiple channels from a technical point of view, and identify a diverse range
of previously undescribed pharmacology.
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Affiliation(s)
| | | | | | | | - Alistair Mathie
- Medway School of Pharmacy, University of Kent, Chatham Maritime, Kent, UK
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12
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K 2P2.1 (TREK-1) potassium channel activation protects against hyperoxia-induced lung injury. Sci Rep 2020; 10:22011. [PMID: 33319831 PMCID: PMC7738539 DOI: 10.1038/s41598-020-78886-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 12/01/2020] [Indexed: 12/20/2022] Open
Abstract
No targeted therapies exist to counteract Hyperoxia (HO)-induced Acute Lung Injury (HALI). We previously found that HO downregulates alveolar K2P2.1 (TREK-1) K+ channels, which results in worsening lung injury. This decrease in TREK-1 levels leaves a subset of channels amendable to pharmacological intervention. Therefore, we hypothesized that TREK-1 activation protects against HALI. We treated HO-exposed mice and primary alveolar epithelial cells (AECs) with the novel TREK-1 activators ML335 and BL1249, and quantified physiological, histological, and biochemical lung injury markers. We determined the effects of these drugs on epithelial TREK-1 currents, plasma membrane potential (Em), and intracellular Ca2+ (iCa) concentrations using fluorometric assays, and blocked voltage-gated Ca2+ channels (CaV) as a downstream mechanism of cytokine secretion. Once-daily, intra-tracheal injections of HO-exposed mice with ML335 or BL1249 improved lung compliance, histological lung injury scores, broncho-alveolar lavage protein levels and cell counts, and IL-6 and IP-10 concentrations. TREK-1 activation also decreased IL-6, IP-10, and CCL-2 secretion from primary AECs. Mechanistically, ML335 and BL1249 induced TREK-1 currents in AECs, counteracted HO-induced cell depolarization, and lowered iCa2+ concentrations. In addition, CCL-2 secretion was decreased after L-type CaV inhibition. Therefore, Em stabilization with TREK-1 activators may represent a novel approach to counteract HALI.
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13
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García G, Méndez-Reséndiz KA, Oviedo N, Murbartián J. PKC- and PKA-dependent phosphorylation modulates TREK-1 function in naïve and neuropathic rats. J Neurochem 2020; 157:2039-2054. [PMID: 33006141 DOI: 10.1111/jnc.15204] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 09/23/2020] [Accepted: 09/25/2020] [Indexed: 02/07/2023]
Abstract
PKC and PKA phosphorylation inhibit TREK-1 channels downstream of Gs protein-coupled receptor activation in vitro. However, the role of phosphorylation of TREK-1 in neuropathic pain is unknown. The purpose of this study was to investigate whether altered TREK-1 channel function by PKA and PKC modulators contributes to antiallodynia in neuropathic rats. Furthermore, we investigated if the in vitro described sites for PKC and PKA phosphorylation (S300 and S333, respectively) participate in the modulation of TREK-1 in naïve and neuropathic rats. L5/L6 spinal nerve ligation (SNL) induced tactile allodynia. Intrathecal injection of BL-1249 (TREK-1 activator) reversed nerve injury-induced tactile allodynia, whereas spadin (TREK-1 blocker) produced tactile allodynia in naïve rats and reversed the antiallodynic effect induced by BL-1249 in neuropathic rats. Intrathecal administration of rottlerin or Rp-cAMPs (PKC and PKA inhibitors, respectively) enhanced the antiallodynia observed with BL-1249 in neuropathic rats. In contrast, pretreatment with PdBu or forskolin (PKC and PKA activators, respectively) reduced the BL-1249-induced antiallodynia. Intrathecal injection of two high-activity TREK-1 recombinant channels, using a in vivo transfection method with lipofectamine, with mutations at PKC/PKA phosphosites (S300A and S333A) reversed tactile allodynia in neuropathic rats, with no effect in naïve rats. In contrast, transfection of two low-activity TREK-1 recombinant channels with phosphomimetic mutations at those sites (S300D and S333D) produced tactile allodynia in naïve rats and interfered with antiallodynic effects of rottlerin/BL-1249 or Rp-cAMPs/BL-1249. Data suggest that TREK-1 channel activity can be dynamically tuned in vivo by PKC/PKA to provoke allodynia and modulate its antiallodynic role in neuropathic pain.
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Affiliation(s)
- Guadalupe García
- Departamento de Farmacobiología, Cinvestav, Sede Sur., Mexico City, Mexico
| | | | - Norma Oviedo
- Unidad de Investigación Médica en Inmunología e Infectología, Centro Médico Nacional, La Raza, Instituto Mexicano del Seguro Social., Mexico City, Mexico
| | - Janet Murbartián
- Departamento de Farmacobiología, Cinvestav, Sede Sur., Mexico City, Mexico
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14
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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.
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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.
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15
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Clinical Importance of the Human Umbilical Artery Potassium Channels. Cells 2020; 9:cells9091956. [PMID: 32854241 PMCID: PMC7565333 DOI: 10.3390/cells9091956] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/21/2020] [Accepted: 08/24/2020] [Indexed: 02/06/2023] Open
Abstract
Potassium (K+) channels are usually predominant in the membranes of vascular smooth muscle cells (SMCs). These channels play an important role in regulating the membrane potential and vessel contractility-a role that depends on the vascular bed. Thus, the activity of K+ channels represents one of the main mechanisms regulating the vascular tone in physiological and pathophysiological conditions. Briefly, the activation of K+ channels in SMC leads to hyperpolarization and vasorelaxation, while its inhibition induces depolarization and consequent vascular contraction. Currently, there are four different types of K+ channels described in SMCs: voltage-dependent K+ (KV) channels, calcium-activated K+ (KCa) channels, inward rectifier K+ (Kir) channels, and 2-pore domain K+ (K2P) channels. Due to the fundamental role of K+ channels in excitable cells, these channels are promising therapeutic targets in clinical practice. Therefore, this review discusses the basic properties of the various types of K+ channels, including structure, cellular mechanisms that regulate their activity, and new advances in the development of activators and blockers of these channels. The vascular functions of these channels will be discussed with a focus on vascular SMCs of the human umbilical artery. Then, the clinical importance of K+ channels in the treatment and prevention of cardiovascular diseases during pregnancy, such as gestational hypertension and preeclampsia, will be explored.
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16
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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.
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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;
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17
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Ma R, Lewis A. Spadin Selectively Antagonizes Arachidonic Acid Activation of TREK-1 Channels. Front Pharmacol 2020; 11:434. [PMID: 32317978 PMCID: PMC7154116 DOI: 10.3389/fphar.2020.00434] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/20/2020] [Indexed: 12/13/2022] Open
Abstract
TREK-1 channel activity is a critical regulator of neuronal, cardiac, and smooth muscle physiology and pathology. The antidepressant peptide, spadin, has been proposed to be a TREK-1-specific blocker. Here we sought to examine the mechanism of action underlying spadin inhibition of TREK-1 channels. Heterologous expression in Xenopus laevis oocytes and electrophysiological analysis using two-electrode voltage clamp in standard bath solutions was used to characterize the pharmacological profile of wild-type and mutant murine TREK-1 and TREK-2 channels using previously established human K2P activators; arachidonic acid (AA), cis-4,7,10,13,16,19-docosahexaenoic acid (DHA), BL-1249, and cinnamyl-3,4-dihydroxy-α-cyanocinnamate (CDC) and inhibitors; spadin and barium (Ba2+). Mouse TREK-1 and TREK-2 channel currents were both significantly increased by AA, BL-1249, and CDC, similar to their human homologs. Under basal conditions, both TREK-1 and TREK-2 currents were insensitive to application of spadin, but could be blocked by Ba2+. Spadin did not significantly inhibit either TREK-1 or TREK-2 currents either chemically activated by AA, BL-1249, or CDC, or structurally activated via a gating mutation. However, pre-exposure to spadin significantly perturbed the subsequent activation of TREK-1 currents by AA, but not TREK-2. Furthermore, spadin was unable to prevent activation of TREK-1 by BL-1249, CDC, or the related bioactive lipid, DHA. Spadin specifically antagonizes the activation of TREK-1 channels by AA, likely via an allosteric mechanism. Lack of intrinsic activity may explain the absence of clinical side effects during antidepressant therapy.
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Affiliation(s)
- Ruolin Ma
- School of Pharmacy and Biomedical Sciences, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Anthony Lewis
- School of Pharmacy and Biomedical Sciences, Institute of Biomedical and Biomolecular Sciences, University of Portsmouth, Portsmouth, United Kingdom
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18
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Rivas-Ramírez P, Reboreda A, Rueda-Ruzafa L, Herrera-Pérez S, Lamas JA. PIP 2 Mediated Inhibition of TREK Potassium Currents by Bradykinin in Mouse Sympathetic Neurons. Int J Mol Sci 2020; 21:ijms21020389. [PMID: 31936257 PMCID: PMC7014146 DOI: 10.3390/ijms21020389] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/30/2019] [Accepted: 01/02/2020] [Indexed: 12/17/2022] Open
Abstract
Bradykinin (BK), a hormone inducing pain and inflammation, is known to inhibit potassium M-currents (IM) and to increase the excitability of the superior cervical ganglion (SCG) neurons by activating the Ca2+-calmodulin pathway. M-current is also reduced by muscarinic agonists through the depletion of membrane phosphatidylinositol 4,5-biphosphate (PIP2). Similarly, the activation of muscarinic receptors inhibits the current through two-pore domain potassium channels (K2P) of the “Tandem of pore-domains in a Weakly Inward rectifying K+ channel (TWIK)-related channels” (TREK) subfamily by reducing PIP2 in mouse SCG neurons (mSCG). The aim of this work was to test and characterize the modulation of TREK channels by bradykinin. We used the perforated-patch technique to investigate riluzole (RIL) activated currents in voltage- and current-clamp experiments. RIL is a drug used in the palliative treatment of amyotrophic lateral sclerosis and, in addition to blocking voltage-dependent sodium channels, it also selectively activates the K2P channels of the TREK subfamily. A cell-attached patch-clamp was also used to investigate TREK-2 single channel currents. We report here that BK reduces spike frequency adaptation (SFA), inhibits the riluzole-activated current (IRIL), which flows mainly through TREK-2 channels, by about 45%, and reduces the open probability of identified single TREK-2 channels in cultured mSCG cells. The effect of BK on IRIL was precluded by the bradykinin receptor (B2R) antagonist HOE-140 (d-Arg-[Hyp3, Thi5, d-Tic7, Oic8]BK) but also by diC8PIP2 which prevents PIP2 depletion when phospholipase C (PLC) is activated. On the contrary, antagonizing inositol triphosphate receptors (IP3R) using 2-aminoethoxydiphenylborane (2-APB) or inhibiting protein kinase C (PKC) with bisindolylmaleimide did not affect the inhibition of IRIL by BK. In conclusion, bradykinin inhibits TREK-2 channels through the activation of B2Rs resulting in PIP2 depletion, much like we have demonstrated for muscarinic agonists. This mechanism implies that TREK channels must be relevant for the capture of information about pain and visceral inflammation.
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19
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Wright PD, McCoull D, Walsh Y, Large JM, Hadrys BW, Gaurilcikaite E, Byrom L, Veale EL, Jerman J, Mathie A. Pranlukast is a novel small molecule activator of the two-pore domain potassium channel TREK2. Biochem Biophys Res Commun 2019; 520:35-40. [DOI: 10.1016/j.bbrc.2019.09.093] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 09/21/2019] [Indexed: 11/29/2022]
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20
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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.
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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.
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21
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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.
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Affiliation(s)
- Daniel Şterbuleac
- Doctoral School of Biology, Faculty of Biology, "Alexandru Ioan Cuza" University of Iasi, Iasi, Romania
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22
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Djillani A, Mazella J, Heurteaux C, Borsotto M. Role of TREK-1 in Health and Disease, Focus on the Central Nervous System. Front Pharmacol 2019; 10:379. [PMID: 31031627 PMCID: PMC6470294 DOI: 10.3389/fphar.2019.00379] [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: 01/14/2019] [Accepted: 03/26/2019] [Indexed: 01/22/2023] Open
Abstract
TREK-1 is the most studied background K2P channel. Its main role is to control cell excitability and maintain the membrane potential below the threshold of depolarization. TREK-1 is multi-regulated by a variety of physical and chemical stimuli which makes it a very promising and challenging target in the treatment of several pathologies. It is mainly expressed in the brain but also in heart, smooth muscle cells, endocrine pancreas, and prostate. In the nervous system, TREK-1 is involved in many physiological and pathological processes such as depression, neuroprotection, pain, and anesthesia. These properties explain why many laboratories and pharmaceutical companies have been focusing their research on screening and developing highly efficient modulators of TREK-1 channels. In this review, we summarize the different roles of TREK-1 that have been investigated so far in attempt to characterize pharmacological tools and new molecules to modulate cellular functions controlled by TREK-1.
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Affiliation(s)
- Alaeddine Djillani
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France
| | - Jean Mazella
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France
| | - Catherine Heurteaux
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France
| | - Marc Borsotto
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR7275, Université Côte d'Azur, Valbonne, France
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23
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Lamas JA, Fernández-Fernández D. Tandem pore TWIK-related potassium channels and neuroprotection. Neural Regen Res 2019; 14:1293-1308. [PMID: 30964046 PMCID: PMC6524494 DOI: 10.4103/1673-5374.253506] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
TWIK-related potassium channels (TREK) belong to a subfamily of the two-pore domain potassium channels family with three members, TREK1, TREK2 and TWIK-related arachidonic acid-activated potassium channels. The two-pore domain potassium channels is the last big family of channels being discovered, therefore it is not surprising that most of the information we know about TREK channels predominantly comes from the study of heterologously expressed channels. Notwithstanding, in this review we pay special attention to the limited amount of information available on native TREK-like channels and real neurons in relation to neuroprotection. Mainly we focus on the role of free fatty acids, lysophospholipids and other neuroprotective agents like riluzole in the modulation of TREK channels, emphasizing on how important this modulation may be for the development of new therapies against neuropathic pain, depression, schizophrenia, epilepsy, ischemia and cardiac complications.
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Affiliation(s)
- J Antonio Lamas
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, Vigo, Galicia, Spain
| | - Diego Fernández-Fernández
- Laboratory of Neuroscience, Biomedical Research Center (CINBIO), University of Vigo, Vigo, Galicia, Spain
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24
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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.
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Affiliation(s)
| | | | | | | | | | | | - Daniel L. Minor
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 United States
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25
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Miranda-Lara CA, Ortiz MI, Rodríguez-Ramos F, Chávez-Piña AE. Synergistic interaction between docosahexaenoic acid and diclofenac on inflammation, nociception, and gastric security models in rats. Drug Dev Res 2018; 79:239-246. [PMID: 30188586 DOI: 10.1002/ddr.21438] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/11/2018] [Indexed: 12/24/2022]
Abstract
Preclinical Research & Development The addition of polyunsaturated fatty acids to nonsteroidal anti-inflammatory drugs can increase their antinociceptive activity and produce a gastroprotective effect. The aim of the present study was to examine the effects of the interaction between docosahexaenoic acid (DHA) and diclofenac on inflammation (fixed ratios 1:1, 1:3, and 3:1), nociception (fixed ratio 1:3), and gastric injury in rats. DHA, diclofenac, or combinations of DHA and diclofenac produced anti-inflammatory and antinociceptive effects in rat. The administration of diclofenac produced significant gastric damage, but this effect was not observed with either DHA or the DHA-diclofenac combinations. Effective dose (ED30 ) values were estimated for each individual drug and analyzed isobolographically. The anti-inflammatory experimental ED30 values were 6.97 mg/kg (1:1 fixed ratio), 1.1 mg/kg (1:3 fixed ratio), and 11.34 mg/kg (3:1 fixed ratio). These values were significantly lower (p < .05) than the theoretical ED30 values: 67.94 mg/kg (1:1), 35.37 mg/kg (1:3), and 100.51 mg/kg (3:1). The antinociceptive experimental value was 1.25 mg/kg (1:3 fixed ratio). This value was lower (p < .05) than the theoretical ED30 , which was predicted to be 15.92 mg/kg. These data indicate that the DHA-diclofenac combinations interact at the systemic level, produce minor gastric damage, and potentially have therapeutic advantages for the clinical treatment of inflammatory pain.
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Affiliation(s)
- Christopher Allan Miranda-Lara
- Maestría en Ciencias en Biomedicina Molecular, Escuela Nacional de Medicina y Homeopatía del Instituto Politécnico Nacional, Ciudad de México, Mexico
| | - Mario I Ortiz
- Área Académica de Medicina del Instituto de Ciencias de la Salud, Universidad Autónoma del Estado de Hidalgo, Pachuca, Hidalgo, Mexico
| | - Fernando Rodríguez-Ramos
- Departamento de Sistemas Biológicos, División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana-Xochimilco, Cuidad de México, Mexico
| | - Aracely Evangelina Chávez-Piña
- Maestría en Ciencias en Biomedicina Molecular, Escuela Nacional de Medicina y Homeopatía del Instituto Politécnico Nacional, Ciudad de México, Mexico.,Laboratorio de Farmacología, Doctorado en Ciencias en Biotecnología, Escuela Nacional de Medicina y Homeopatía del Instituto Politécnico Nacional, Ciudad de México, Mexico
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26
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Gada K, Plant LD. Two-pore domain potassium channels: emerging targets for novel analgesic drugs: IUPHAR Review 26. Br J Pharmacol 2018; 176:256-266. [PMID: 30325008 DOI: 10.1111/bph.14518] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/23/2018] [Accepted: 08/18/2018] [Indexed: 01/02/2023] Open
Abstract
Chronic pain is a debilitating and increasingly common medical problem with few effective treatments. In addition to the direct and indirect economic burden of pain syndromes, the concomitant increase in prescriptions for narcotics has contributed to a sharp rise in deaths associated with drug misuse - the 'opioid crisis'. Together, these issues highlight the unmet clinical and social need for a new generation of safe, efficacious analgesics. The detection and transmission of pain stimuli is largely mediated by somatosensory afferent fibres of the dorsal root ganglia. These nociceptive cells express an array of membrane proteins that have received significant attention as attractive targets for new pain medications. Among these, a growing body of evidence supports a role for the two-pore domain potassium (K2P) family of K+ channels. Here, we provide a concise review of the K2P channels, their role in pain biology and their potential as targets for novel analgesic agents.
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Affiliation(s)
- Kirin Gada
- Department of Pharmaceutical Sciences in the School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| | - Leigh D Plant
- Department of Pharmaceutical Sciences in the School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
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27
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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).
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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
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28
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Fernández-Fernández D, Cadaveira-Mosquera A, Rueda-Ruzafa L, Herrera-Pérez S, Veale EL, Reboreda A, Mathie A, Lamas JA. Activation of TREK currents by riluzole in three subgroups of cultured mouse nodose ganglion neurons. PLoS One 2018; 13:e0199282. [PMID: 29928032 PMCID: PMC6013220 DOI: 10.1371/journal.pone.0199282] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 06/05/2018] [Indexed: 01/12/2023] Open
Abstract
Two-pore domain potassium channels (K2P) constitute major candidates for the regulation of background potassium currents in mammalian cells. Channels of the TREK subfamily are also well positioned to play an important role in sensory transduction due to their sensitivity to a large number of physiological and physical stimuli (pH, mechanical, temperature). Following our previous report describing the molecular expression of different K2P channels in the vagal sensory system, here we confirm that TREK channels are functionally expressed in neurons from the mouse nodose ganglion (mNG). Neurons were subdivided into three groups (A, Ah and C) based on their response to tetrodotoxin and capsaicin. Application of the TREK subfamily activator riluzole to isolated mNG neurons evoked a concentration-dependent outward current in the majority of cells from all the three subtypes studied. Riluzole increased membrane conductance and hyperpolarized the membrane potential by approximately 10 mV when applied to resting neurons. The resting potential was similar in all three groups, but C cells were clearly less excitable and showed smaller hyperpolarization-activated currents at -100 mV and smaller sustained currents at -30 mV. Our results indicate that the TREK subfamily of K2P channels might play an important role in the maintenance of the resting membrane potential in sensory neurons of the autonomic nervous system, suggesting its participation in the modulation of vagal reflexes.
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Affiliation(s)
- Diego Fernández-Fernández
- Department of Functional Biology and Health Sciences, Faculty of Biology–CINBIO, University of Vigo, Vigo, Galicia, Spain
- * E-mail: (DFF); (JAL)
| | - Alba Cadaveira-Mosquera
- Department of Functional Biology and Health Sciences, Faculty of Biology–CINBIO, University of Vigo, Vigo, Galicia, Spain
| | - Lola Rueda-Ruzafa
- Department of Functional Biology and Health Sciences, Faculty of Biology–CINBIO, University of Vigo, Vigo, Galicia, Spain
| | - Salvador Herrera-Pérez
- Department of Functional Biology and Health Sciences, Faculty of Biology–CINBIO, University of Vigo, Vigo, Galicia, Spain
| | - Emma L. Veale
- Medway School of Pharmacy, University of Kent, Chatham Maritime, Kent, United Kingdom
| | - Antonio Reboreda
- Department of Functional Biology and Health Sciences, Faculty of Biology–CINBIO, University of Vigo, Vigo, Galicia, Spain
| | - Alistair Mathie
- Medway School of Pharmacy, University of Kent, Chatham Maritime, Kent, United Kingdom
| | - J. Antonio Lamas
- Department of Functional Biology and Health Sciences, Faculty of Biology–CINBIO, University of Vigo, Vigo, Galicia, Spain
- * E-mail: (DFF); (JAL)
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29
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Loucif AJC, Saintot P, Liu J, Antonio BM, Zellmer SG, Yoger K, Veale EL, Wilbrey A, Omoto K, Cao L, Gutteridge A, Castle NA, Stevens EB, Mathie A. GI-530159, a novel, selective, mechanosensitive two-pore-domain potassium (K 2P ) channel opener, reduces rat dorsal root ganglion neuron excitability. Br J Pharmacol 2018; 175:2272-2283. [PMID: 29150838 PMCID: PMC5980259 DOI: 10.1111/bph.14098] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 11/09/2017] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE TREK two-pore-domain potassium (K2P ) channels play a critical role in regulating the excitability of somatosensory nociceptive neurons and are important mediators of pain perception. An understanding of the roles of TREK channels in pain perception and, indeed, in other pathophysiological conditions, has been severely hampered by the lack of potent and/or selective activators and inhibitors. In this study, we describe a new, selective opener of TREK channels, GI-530159. EXPERIMENTAL APPROACH The effect of GI-530159 on TREK channels was demonstrated using 86 Rb efflux assays, whole-cell and single-channel patch-clamp recordings from recombinant TREK channels. The expression of K2P 2.1 (TREK1), K2P 10.1 (TREK2) and K2P 4.1 (TRAAK) channels was determined using transcriptome analysis from single dorsal root ganglion (DRG) cells. Current-clamp recordings from cultured rat DRG neurons were used to measure the effect of GI-530159 on neuronal excitability. KEY RESULTS For recombinant human TREK1 channels, GI-530159 had similar low EC50 values in Rb efflux experiments and electrophysiological recordings. It activated TREK2 channels, but it had no detectable action on TRAAK channels nor any significant effect on other K channels tested. Current-clamp recordings from cultured rat DRG neurones showed that application of GI-530159 at 1 μM resulted in a significant reduction in firing frequency and a small hyperpolarization of resting membrane potential. CONCLUSIONS AND IMPLICATIONS This study provides pharmacological evidence for the presence of mechanosensitive TREK K2P channels in sensory neurones and suggests that development of selective K2P channel openers like GI-530159 could aid in the development of novel analgesic agents. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Affiliation(s)
| | | | | | | | | | | | - Emma L Veale
- Medway School of PharmacyUniversity of KentChatham MaritimeKentUK
| | | | | | | | | | | | | | - Alistair Mathie
- Medway School of PharmacyUniversity of KentChatham MaritimeKentUK
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30
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Ma R, Seifi M, Papanikolaou M, Brown JF, Swinny JD, Lewis A. TREK-1 Channel Expression in Smooth Muscle as a Target for Regulating Murine Intestinal Contractility: Therapeutic Implications for Motility Disorders. Front Physiol 2018; 9:157. [PMID: 29563879 PMCID: PMC5845753 DOI: 10.3389/fphys.2018.00157] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/16/2018] [Indexed: 11/24/2022] Open
Abstract
Gastrointestinal (GI) motility disorders such as irritable bowel syndrome (IBS) can occur when coordinated smooth muscle contractility is disrupted. Potassium (K+) channels regulate GI smooth muscle tone and are key to GI tract relaxation, but their molecular and functional phenotypes are poorly described. Here we define the expression and functional roles of mechano-gated K2P channels in mouse ileum and colon. Expression and distribution of the K2P channel family were investigated using quantitative RT-PCR (qPCR), immunohistochemistry and confocal microscopy. The contribution of mechano-gated K2P channels to mouse intestinal muscle tension was studied pharmacologically using organ bath. Multiple K2P gene transcripts were detected in mouse ileum and colon whole tissue preparations. Immunohistochemistry confirmed TREK-1 expression was smooth muscle specific in both ileum and colon, whereas TREK-2 and TRAAK channels were detected in enteric neurons but not smooth muscle. In organ bath, mechano-gated K2P channel activators (Riluzole, BL-1249, flufenamic acid, and cinnamyl 1-3,4-dihydroxy-alpha-cyanocinnamate) induced relaxation of KCl and CCh pre-contracted ileum and colon tissues and reduced the amplitude of spontaneous contractions. These data reveal the specific expression of mechano-gated K2P channels in mouse ileum and colon tissues and highlight TREK-1, a smooth muscle specific K2P channel in GI tract, as a potential therapeutic target for combating motility pathologies arising from hyper-contractility.
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Affiliation(s)
- Ruolin Ma
- School of Pharmacy and Biomedical Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Mohsen Seifi
- School of Pharmacy and Biomedical Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Maria Papanikolaou
- School of Pharmacy and Biomedical Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - James F Brown
- School of Pharmacy and Biomedical Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Jerome D Swinny
- School of Pharmacy and Biomedical Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Anthony Lewis
- School of Pharmacy and Biomedical Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
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31
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Ortiz MI, Cariño-Cortés R, Ponce-Monter HA, Castañeda-Hernández G, Chávez-Piña AE. Pharmacological interaction of α-bisabolol and diclofenac on nociception, inflammation, and gastric integrity in rats. Drug Dev Res 2017; 79:29-37. [DOI: 10.1002/ddr.21418] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 11/26/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Mario I. Ortiz
- Área Académica de Medicina del Instituto de Ciencias de la Salud, Universidad Autónoma del Estado de Hidalgo; Pachuca Hidalgo Mexico
| | - Raquel Cariño-Cortés
- Área Académica de Medicina del Instituto de Ciencias de la Salud, Universidad Autónoma del Estado de Hidalgo; Pachuca Hidalgo Mexico
| | - Héctor A. Ponce-Monter
- Área Académica de Medicina del Instituto de Ciencias de la Salud, Universidad Autónoma del Estado de Hidalgo; Pachuca Hidalgo Mexico
| | - Gilberto Castañeda-Hernández
- Departamento de Farmacología; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional; Ciudad de México Mexico
| | - Aracely Evangelina Chávez-Piña
- Laboratorio de Farmacología, Programa Institucional en Biomedicina Molecular; Escuela Nacional de Medicina y Homeopatía del Instituto Politécnico Nacional; Ciudad de México Mexico
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32
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Decher N, Ortiz-Bonnin B, Friedrich C, Schewe M, Kiper AK, Rinné S, Seemann G, Peyronnet R, Zumhagen S, Bustos D, Kockskämper J, Kohl P, Just S, González W, Baukrowitz T, Stallmeyer B, Schulze-Bahr E. Sodium permeable and "hypersensitive" TREK-1 channels cause ventricular tachycardia. EMBO Mol Med 2017; 9:403-414. [PMID: 28242754 PMCID: PMC5376757 DOI: 10.15252/emmm.201606690] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In a patient with right ventricular outflow tract (RVOT) tachycardia, we identified a heterozygous point mutation in the selectivity filter of the stretch-activated K2P potassium channel TREK-1 (KCNK2 or K2P2.1). This mutation introduces abnormal sodium permeability to TREK-1. In addition, mutant channels exhibit a hypersensitivity to stretch-activation, suggesting that the selectivity filter is directly involved in stretch-induced activation and desensitization. Increased sodium permeability and stretch-sensitivity of mutant TREK-1 channels may trigger arrhythmias in areas of the heart with high physical strain such as the RVOT We present a pharmacological strategy to rescue the selectivity defect of the TREK-1 pore. Our findings provide important insights for future studies of K2P channel stretch-activation and the role of TREK-1 in mechano-electrical feedback in the heart.
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Affiliation(s)
- Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Beatriz Ortiz-Bonnin
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Corinna Friedrich
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Marcus Schewe
- Institute of Physiology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg, Marburg, Germany
| | - Gunnar Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sven Zumhagen
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Daniel Bustos
- Center for Bioinformatics and Molecular Simulation, University of Talca, Talca, Chile
| | - Jens Kockskämper
- Institute of Pharmacology and Clinical Pharmacy, Biochemical and Pharmacological Center (BPC) Philipps-University of Marburg, Marburg, Germany
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, Medical Center - University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Steffen Just
- Molecular Cardiology, University Hospital Ulm, Ulm, Germany
| | - Wendy González
- Center for Bioinformatics and Molecular Simulation, University of Talca, Talca, Chile
| | - Thomas Baukrowitz
- Institute of Physiology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Birgit Stallmeyer
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Münster, Germany
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33
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Nematian-Ardestani E, Jarerattanachat V, Aryal P, Sansom MSP, Tucker SJ. The effects of stretch activation on ionic selectivity of the TREK-2 K2P K + channel. Channels (Austin) 2017; 11:482-486. [PMID: 28723241 PMCID: PMC5626358 DOI: 10.1080/19336950.2017.1356955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The TREK-2 (KCNK10) K2P potassium channel can be regulated by variety of polymodal stimuli including pressure. In a recent study, we demonstrated that this mechanosensitive K+ channel responds to changes in membrane tension by undergoing a major structural change from its ‘down’ state to the more expanded ‘up’ state conformation. These changes are mostly restricted to the lower part of the protein within the bilayer, but are allosterically coupled to the primary gating mechanism located within the selectivity filter. However, any such structural changes within the filter also have the potential to alter ionic selectivity and there are reports that some K2Ps, including TREK channels, exhibit a dynamic ionic selectivity. In this addendum to our previous study we have therefore examined whether the selectivity of TREK-2 is altered by stretch activation. Our results reveal that the filter remains stable and highly selective for K+ over Na+ during stretch activation, and that permeability to a range of other cations (Rb+, Cs+ and NH4+) also does not change. The asymmetric structural changes that occur during stretch activation therefore allow the channel to respond to changes in membrane tension without a loss of K+ selectivity.
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Affiliation(s)
- Ehsan Nematian-Ardestani
- a Clarendon Laboratory, Department of Physics and OXION Initiative in Ion Channels and Disease , University of Oxford , Oxford , UK
| | - Viwan Jarerattanachat
- a Clarendon Laboratory, Department of Physics and OXION Initiative in Ion Channels and Disease , University of Oxford , Oxford , UK
| | - Prafulla Aryal
- a Clarendon Laboratory, Department of Physics and OXION Initiative in Ion Channels and Disease , University of Oxford , Oxford , UK
| | - Mark S P Sansom
- a Clarendon Laboratory, Department of Physics and OXION Initiative in Ion Channels and Disease , University of Oxford , Oxford , UK
| | - Stephen J Tucker
- a Clarendon Laboratory, Department of Physics and OXION Initiative in Ion Channels and Disease , University of Oxford , Oxford , UK
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34
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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.
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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
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35
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Decher N, Kiper AK, Rinné S. Stretch-activated potassium currents in the heart: Focus on TREK-1 and arrhythmias. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:223-232. [PMID: 28526352 DOI: 10.1016/j.pbiomolbio.2017.05.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/09/2017] [Accepted: 05/15/2017] [Indexed: 12/26/2022]
Abstract
This review focuses on the role and the molecular candidates of the cardiac stretch-activated potassium current (SAK). The functional properties of the two-pore domain potassium (K2P) channel TREK-1, a major candidate for the cardiac SAK, are analyzed and the molecular mechanism of stretch-activation in K2P potassium channels is discussed. Furthermore, the functional modulation of TREK-1 by different cardiac interaction partners, as well as evidence for the functional role of the stretch-dependent TREK-1 and its putative subunits in the heart is reviewed. In addition, we summarize the recent evidence that TREK-1 is involved in the pathogenesis of human cardiac arrhythmias.
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Affiliation(s)
- Niels Decher
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Deutschhausstrasse 1-2, 35037 Marburg, Germany.
| | - Aytug K Kiper
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Deutschhausstrasse 1-2, 35037 Marburg, Germany
| | - Susanne Rinné
- Institute for Physiology and Pathophysiology, AG Vegetative Physiology, Deutschhausstrasse 1-2, 35037 Marburg, Germany
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36
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Shaikh SS, Chen YC, Halsall SA, Nahorski MS, Omoto K, Young GT, Phelan A, Woods CG. A Comprehensive Functional Analysis of NTRK1 Missense Mutations Causing Hereditary Sensory and Autonomic Neuropathy Type IV (HSAN IV). Hum Mutat 2016; 38:55-63. [PMID: 27676246 PMCID: PMC5299464 DOI: 10.1002/humu.23123] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/19/2016] [Accepted: 09/07/2016] [Indexed: 11/07/2022]
Abstract
Hereditary sensory and autonomic neuropathy type IV (HSAN IV) is an autosomal recessive disorder characterized by a complete lack of pain perception and anhidrosis. Here, we studied a cohort of seven patients with HSAN IV and describe a comprehensive functional analysis of seven novel NTRK1 missense mutations, c.1550G >A, c.1565G >A, c.1970T >C, c.2096T >C, c.2254T >A, c.2288G >C, and c.2311C >T, corresponding to p.G517E, p.G522E, p.L657P, p.I699T, p.C752S, p.C763S, and p.R771C, all of which were predicted pathogenic by in silico analysis. The results allowed us to assess the pathogenicity of each mutation and to gain novel insights into tropomyosin receptor kinase A (TRKA) downstream signaling. Each mutation was systematically analyzed for TRKA glycosylation states, intracellular and cell membrane expression patterns, nerve growth factor stimulated TRKA autophosphorylation, TRKA-Y496 phosphorylation, PLCγ activity, and neurite outgrowth. We showed a diverse range of functional effects: one mutation appeared fully functional, another had partial activity in all assays, one mutation affected only the PLCγ pathway and four mutations were proved null in all assays. Thus, we conclude that complete abolition of TRKA kinase activity is not the only pathogenic mechanism underlying HSAN IV. By corollary, the assessment of the clinical pathogenicity of HSAN IV mutations is more complex than initially predicted and requires a multifaceted approach.
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Affiliation(s)
- Samiha S Shaikh
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Ya-Chun Chen
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | | | - Michael S Nahorski
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Kiyoyuki Omoto
- Neuroscience and Pain Research Unit, Pfizer Ltd, Great Abington, UK
| | - Gareth T Young
- Neuroscience and Pain Research Unit, Pfizer Ltd, Great Abington, UK
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37
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Weng W, Chen Y, Wang M, Zhuang Y, Behnisch T. Potentiation of Schaffer-Collateral CA1 Synaptic Transmission by eEF2K and p38 MAPK Mediated Mechanisms. Front Cell Neurosci 2016; 10:247. [PMID: 27826228 PMCID: PMC5078695 DOI: 10.3389/fncel.2016.00247] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/10/2016] [Indexed: 12/20/2022] Open
Abstract
The elongation factor 2 kinase (eEF2K), likewise known as CaMKIII, has been demonstrated to be involved in antidepressant responses of NMDA receptor antagonists. Even so, it remains open whether direct inhibition of eEF2K without altering up-stream or other signaling pathways affects hippocampal synaptic transmission and neuronal network synchrony. Inhibition of eEF2K by the selective and potent eEF2K inhibitor A-484954 induced a fast pre-synaptically mediated enhancement of synaptic transmission and synchronization of neural network activity. The eEF2K-inhibition mediated potentiation of synaptic transmission of hippocampal CA1 neurons is most notably independent of protein synthesis and does not rely on protein kinase C, protein kinase A or mitogen-activated protein kinase (MAPK)/extracellular signal-regulated protein kinase 1/2. Moreover, the strengthening of synaptic transmission in the response to the inhibition of eEF2K was strongly attenuated by the inhibition of p38 MAPK. In addition, we show the involvement of barium-sensitive and more specific the TWIK-related potassium-1 (TREK-1) channels in the eEF2K-inhibition mediated potentiation of synaptic transmission. These findings reveal a novel pathway of eEF2K mediated regulation of hippocampal synaptic transmission. Further research is required to study whether such compounds could be beneficial for the development of mood disorder treatments with a fast-acting antidepressant response.
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Affiliation(s)
- Weiguang Weng
- The Institutes of Brain Science, The State Key Laboratory of Medical Neurobiology, and the Collaborative Innovation Center for Brain Science, Fudan University Shanghai, China
| | - Ying Chen
- The Institutes of Brain Science, The State Key Laboratory of Medical Neurobiology, and the Collaborative Innovation Center for Brain Science, Fudan University Shanghai, China
| | - Man Wang
- The Institutes of Brain Science, The State Key Laboratory of Medical Neurobiology, and the Collaborative Innovation Center for Brain Science, Fudan University Shanghai, China
| | - Yinghan Zhuang
- The Institutes of Brain Science, The State Key Laboratory of Medical Neurobiology, and the Collaborative Innovation Center for Brain Science, Fudan University Shanghai, China
| | - Thomas Behnisch
- The Institutes of Brain Science, The State Key Laboratory of Medical Neurobiology, and the Collaborative Innovation Center for Brain Science, Fudan University Shanghai, China
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Monteillier A, Loucif A, Omoto K, Stevens EB, Lainez S, Saintot PP, Cao L, Pryde DC. Investigation of the structure activity relationship of flufenamic acid derivatives at the human TRESK channel K 2P 18.1. Bioorg Med Chem Lett 2016; 26:4919-4924. [DOI: 10.1016/j.bmcl.2016.09.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 11/30/2022]
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Reed AP, Bucci G, Abd-Wahab F, Tucker SJ. Dominant-Negative Effect of a Missense Variant in the TASK-2 (KCNK5) K+ Channel Associated with Balkan Endemic Nephropathy. PLoS One 2016; 11:e0156456. [PMID: 27228168 PMCID: PMC4882002 DOI: 10.1371/journal.pone.0156456] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 05/14/2016] [Indexed: 11/20/2022] Open
Abstract
TASK-2, a member of the Two-Pore Domain (K2P) subfamily of K+ channels, is encoded by the KCNK5 gene. The channel is expressed primarily in renal epithelial tissues and a potentially deleterious missense variant in KCNK5 has recently been shown to be prevalent amongst patients predisposed to the development of Balkan Endemic Nephropathy (BEN), a chronic tubulointerstitial renal disease of unknown etiology. In this study we show that this variant (T108P) results in a complete loss of channel function and is associated with a major reduction in TASK-2 channel subunits at the cell surface. Furthermore, these mutant subunits have a suppressive or ‘dominant-negative’ effect on channel function when coexpressed with wild-type subunits. This missense variant is located at the extracellular surface of the M2 transmembrane helix and by using a combination of structural modelling and further functional analysis we also show that this highly-conserved threonine residue is critical for the correct function of other K2P channels. These results therefore provide further structural and functional insights into the possible pathophysiological effects of this missense variant in TASK-2.
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Affiliation(s)
- Alan P. Reed
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Giovanna Bucci
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Firdaus Abd-Wahab
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Stephen J. Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
- OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Veale EL, Mathie A. Aristolochic acid, a plant extract used in the treatment of pain and linked to Balkan endemic nephropathy, is a regulator of K2P channels. Br J Pharmacol 2016; 173:1639-52. [PMID: 26914156 PMCID: PMC4842925 DOI: 10.1111/bph.13465] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 02/08/2016] [Accepted: 02/15/2016] [Indexed: 01/08/2023] Open
Abstract
Background and Purpose Aristolochic acid (AristA) is found in plants used in traditional medicines to treat pain. We investigated the action of AristA on TREK and TRESK, potassium (K2P) channels, which are potential therapeutic targets in pain. Balkan endemic nephropathy (BEN) is a renal disease associated with AristA consumption. A mutation of TASK‐2 (K2P5.1) channels (T108P) is seen in some patients susceptible to BEN, so we investigated how both this mutation and AristA affected TASK‐2 channels. Experimental Approach 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 AristA. Key Results TREK‐1‐ and TREK‐2‐mediated currents were enhanced by AristA (100 μM), whereas TRESK was inhibited. Inhibition of TRESK did not depend on the phosphorylation of key intracellular serines but was completely blocked by mutation of bulky residues in the inner pore (F145A_F352A). The TASK‐2_T108P mutation markedly reduced both current density and ion selectivity. A related mutation (T108C) had similar but less marked effects. External alkalization and application of flufenamic acid enhanced TASK‐2 and TASK‐2_T108C current but did not affect TASK‐2_T108P current. AristA (300 μM) produced a modest enhancement of TASK‐2 current. Conclusions and Implications Enhancement of TREK‐1 and TREK‐2 and inhibition of TRESK by AristA may contribute to therapeutically useful effects of this compound in pain. Whilst AristA is unlikely to interact directly with TASK‐2 channels in BEN, loss of functional TASK‐2 channels may indirectly increase susceptibility to AristA toxicity.
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Affiliation(s)
- Emma L Veale
- Medway School of Pharmacy, University of Kent, Kent, UK
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Mixing and matching TREK/TRAAK subunits generate heterodimeric K2P channels with unique properties. Proc Natl Acad Sci U S A 2016; 113:4200-5. [PMID: 27035965 DOI: 10.1073/pnas.1522748113] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The tandem of pore domain in a weak inwardly rectifying K(+) channel (Twik)-related acid-arachidonic activated K(+) channel (TRAAK) and Twik-related K(+) channels (TREK) 1 and TREK2 are active as homodimers gated by stretch, fatty acids, pH, and G protein-coupled receptors. These two-pore domain potassium (K2P) channels are broadly expressed in the nervous system where they control excitability. TREK/TRAAK KO mice display altered phenotypes related to nociception, neuroprotection afforded by polyunsaturated fatty acids, learning and memory, mood control, and sensitivity to general anesthetics. These channels have emerged as promising targets for the development of new classes of anesthetics, analgesics, antidepressants, neuroprotective agents, and drugs against addiction. Here, we show that the TREK1, TREK2, and TRAAK subunits assemble and form active heterodimeric channels with electrophysiological, regulatory, and pharmacological properties different from those of homodimeric channels. Heteromerization occurs between all TREK variants produced by alternative splicing and alternative translation initiation. These results unveil a previously unexpected diversity of K2P channels that will be challenging to analyze in vivo, but which opens new perspectives for the development of clinically relevant drugs.
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Vivier D, Bennis K, Lesage F, Ducki S. Perspectives on the Two-Pore Domain Potassium Channel TREK-1 (TWIK-Related K(+) Channel 1). A Novel Therapeutic Target? J Med Chem 2015; 59:5149-57. [PMID: 26588045 DOI: 10.1021/acs.jmedchem.5b00671] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Potassium (K(+)) channels are membrane proteins expressed in most living cells that selectively control the flow of K(+) ions. More than 80 genes encode the K(+) channel subunits in the human genome. The TWIK-related K(+) channel (TREK-1) belongs to the two-pore domain K(+) channels (K2P) and displays various properties including sensitivity to physical (membrane stretch, acidosis, temperature) and chemical stimuli (signaling lipids, volatile anesthetics). The distribution of TREK-1 in the central nervous system, coupled with the physiological consequences of its opening and closing, leads to the emergence of this channel as an attractive therapeutic target. We review the TREK-1 channel, its structural and functional properties, and the pharmacological agents (agonists and antagonists) able to modulate its gating.
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Affiliation(s)
- Delphine Vivier
- Université Clermont Auvergne, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.,CNRS, UMR6296, ICCF, F-63171 Aubiere, France
| | - Khalil Bennis
- Université Clermont Auvergne, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.,CNRS, UMR6296, ICCF, F-63171 Aubiere, France
| | - Florian Lesage
- Labex ICST, Institut de Pharmacologie Moléculaire et Cellulaire, UMR CNRS 7275, Université de Nice Sophia Antipolis, F-06560 Valbonne, France
| | - Sylvie Ducki
- Université Clermont Auvergne, ENSCCF, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.,CNRS, UMR6296, ICCF, F-63171 Aubiere, France
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Dong YY, Pike ACW, Mackenzie A, McClenaghan C, Aryal P, Dong L, Quigley A, Grieben M, Goubin S, Mukhopadhyay S, Ruda GF, Clausen MV, Cao L, Brennan PE, Burgess-Brown NA, Sansom MSP, Tucker SJ, Carpenter EP. K2P channel gating mechanisms revealed by structures of TREK-2 and a complex with Prozac. Science 2015; 347:1256-9. [PMID: 25766236 DOI: 10.1126/science.1261512] [Citation(s) in RCA: 212] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
TREK-2 (KCNK10/K2P10), a two-pore domain potassium (K2P) channel, is gated by multiple stimuli such as stretch, fatty acids, and pH and by several drugs. However, the mechanisms that control channel gating are unclear. Here we present crystal structures of the human TREK-2 channel (up to 3.4 angstrom resolution) in two conformations and in complex with norfluoxetine, the active metabolite of fluoxetine (Prozac) and a state-dependent blocker of TREK channels. Norfluoxetine binds within intramembrane fenestrations found in only one of these two conformations. Channel activation by arachidonic acid and mechanical stretch involves conversion between these states through movement of the pore-lining helices. These results provide an explanation for TREK channel mechanosensitivity, regulation by diverse stimuli, and possible off-target effects of the serotonin reuptake inhibitor Prozac.
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Affiliation(s)
- Yin Yao Dong
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Ashley C W Pike
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Alexandra Mackenzie
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK. Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Conor McClenaghan
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK. OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PN, UK
| | - Prafulla Aryal
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK. OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PN, UK. Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Liang Dong
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Andrew Quigley
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Mariana Grieben
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | - Solenne Goubin
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | | | - Gian Filippo Ruda
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK. Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | - Michael V Clausen
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Lishuang Cao
- Pfizer Neusentis, Granta Park, Cambridge CB21 6GS, UK
| | - Paul E Brennan
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK. Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford OX3 7FZ, UK
| | | | - Mark S P Sansom
- OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PN, UK. Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Stephen J Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK. OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PN, UK.
| | - Elisabeth P Carpenter
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK. OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PN, UK.
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Sepúlveda FV, Pablo Cid L, Teulon J, Niemeyer MI. Molecular aspects of structure, gating, and physiology of pH-sensitive background K2P and Kir K+-transport channels. Physiol Rev 2015; 95:179-217. [PMID: 25540142 DOI: 10.1152/physrev.00016.2014] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
K(+) channels fulfill roles spanning from the control of excitability to the regulation of transepithelial transport. Here we review two groups of K(+) channels, pH-regulated K2P channels and the transport group of Kir channels. After considering advances in the molecular aspects of their gating based on structural and functional studies, we examine their participation in certain chosen physiological and pathophysiological scenarios. Crystal structures of K2P and Kir channels reveal rather unique features with important consequences for the gating mechanisms. Important tasks of these channels are discussed in kidney physiology and disease, K(+) homeostasis in the brain by Kir channel-equipped glia, and central functions in the hearing mechanism in the inner ear and in acid secretion by parietal cells in the stomach. K2P channels fulfill a crucial part in central chemoreception probably by virtue of their pH sensitivity and are central to adrenal secretion of aldosterone. Finally, some unorthodox behaviors of the selectivity filters of K2P channels might explain their normal and pathological functions. Although a great deal has been learned about structure, molecular details of gating, and physiological functions of K2P and Kir K(+)-transport channels, this has been only scratching at the surface. More molecular and animal studies are clearly needed to deepen our knowledge.
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Affiliation(s)
- Francisco V Sepúlveda
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - L Pablo Cid
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - Jacques Teulon
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - María Isabel Niemeyer
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
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Mathie A, Veale EL. Two-pore domain potassium channels: potential therapeutic targets for the treatment of pain. Pflugers Arch 2014; 467:931-43. [DOI: 10.1007/s00424-014-1655-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/11/2014] [Accepted: 11/13/2014] [Indexed: 01/01/2023]
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