1
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Oyama M, Watanabe S, Iwai T, Tanabe M. Selective inhibition of A-fiber-mediated excitatory transmission underlies the analgesic effects of KCNQ channel opening in the spinal dorsal horn. Neuropharmacology 2024; 254:109994. [PMID: 38750803 DOI: 10.1016/j.neuropharm.2024.109994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 04/11/2024] [Accepted: 05/10/2024] [Indexed: 05/18/2024]
Abstract
Neuronal voltage-gated KCNQ (Kv7) channels, expressed centrally and peripherally, mediate low-threshold and non-inactivating M-currents responsible for the control of tonic excitability of mammalian neurons. Pharmacological opening of KCNQ channels has been reported to generate analgesic effects in animal models of neuropathic pain. Here, we examined the possible involvement of central KCNQ channels in the analgesic effects of retigabine, a KCNQ channel opener. Behaviorally, intraperitoneally applied retigabine exerted analgesic effects on thermal and mechanical hypersensitivity in male mice developing neuropathic pain after partial sciatic nerve ligation, which was antagonized by the KCNQ channel blocker XE991 preadministered intraperitoneally and intrathecally. Intrathecally applied retigabine also exerted analgesic effects that were inhibited by intrathecally injected XE991. We then explored the synaptic mechanisms underlying the analgesic effects of retigabine in the spinal dorsal horn. Whole-cell recordings were made from dorsal horn neurons in spinal slices with attached dorsal roots from adult male mice developing neuropathic pain, and the effects of retigabine on miniature and afferent-evoked postsynaptic currents were examined. Retigabine reduced the amplitude of A-fiber-mediated EPSCs without affecting C-fiber-mediated excitatory synaptic transmission. A-fiber-mediated EPSCs remained unaltered by retigabine in the presence of XE991, consistently with the behavioral findings. The frequency and amplitude of mEPSCs were not affected by retigabine. Thus, opening of KCNQ channels in the central terminals of primary afferent A-fibers inhibits excitatory synaptic transmission in the spinal dorsal horn, most likely contributing to the analgesic effect of retigabine.
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Affiliation(s)
- Misa Oyama
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan
| | - Shun Watanabe
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan
| | - Takashi Iwai
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan
| | - Mitsuo Tanabe
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan.
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2
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Chuinsiri N, Siraboriphantakul N, Kendall L, Yarova P, Nile CJ, Song B, Obara I, Durham J, Telezhkin V. Calcium-sensing receptor regulates Kv7 channels via G i/o protein signalling and modulates excitability of human induced pluripotent stem cell-derived nociceptive-like neurons. Br J Pharmacol 2024; 181:2676-2696. [PMID: 38627101 DOI: 10.1111/bph.16349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 01/29/2024] [Accepted: 02/15/2024] [Indexed: 07/03/2024] Open
Abstract
BACKGROUND AND PURPOSE Neuropathic pain, a debilitating condition with unmet medical needs, can be characterised as hyperexcitability of nociceptive neurons caused by dysfunction of ion channels. Voltage-gated potassium channels type 7 (Kv7), responsible for maintaining neuronal resting membrane potential and thus excitability, reside under tight control of G protein-coupled receptors (GPCRs). Calcium-sensing receptor (CaSR) is a GPCR that regulates the activity of numerous ion channels, but whether CaSR can control Kv7 channel function has been unexplored until now. EXPERIMENTAL APPROACH Experiments were conducted in recombinant cell models, mouse dorsal root ganglia (DRG) neurons and human induced pluripotent stem cell (hiPSC)-derived nociceptive-like neurons using patch-clamp electrophysiology and molecular biology techniques. KEY RESULTS Our results demonstrate that CaSR is expressed in recombinant cell models, hiPSC-derived nociceptive-like neurons and mouse DRG neurons, and its activation induced depolarisation via Kv7.2/7.3 channel inhibition. The CaSR-Kv7.2/7.3 channel crosslink was mediated via the Gi/o protein-adenylate cyclase-cyclicAMP-protein kinase A signalling cascade. Suppression of CaSR function demonstrated a potential to rescue hiPSC-derived nociceptive-like neurons from algogenic cocktail-induced hyperexcitability. CONCLUSION AND IMPLICATIONS This study demonstrates that the CaSR-Kv7.2/7.3 channel crosslink, via a Gi/o protein signalling pathway, effectively regulates neuronal excitability, providing a feasible pharmacological target for neuronal hyperexcitability management in neuropathic pain.
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Affiliation(s)
- Nontawat Chuinsiri
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
- Institute of Dentistry, Suranaree University of Technology, Nakhon Ratchasima, Thailand
- Oral Health Center, Suranaree University of TechnologyHospital, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | | | - Luke Kendall
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Polina Yarova
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Christopher J Nile
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Bing Song
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
- School of Dentistry, College of Biomedical and Life Sciences, Cardiff University, Cardiff, UK
| | - Ilona Obara
- School of Pharmacy, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Justin Durham
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Vsevolod Telezhkin
- School of Dental Sciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
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3
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Stagno C, Mancuso F, Ciaglia T, Ostacolo C, Piperno A, Iraci N, Micale N. In Silico Methods for the Discovery of Kv7.2/7.3 Channels Modulators: A Comprehensive Review. Molecules 2024; 29:3234. [PMID: 38999185 PMCID: PMC11243076 DOI: 10.3390/molecules29133234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2024] [Revised: 07/03/2024] [Accepted: 07/05/2024] [Indexed: 07/14/2024] Open
Abstract
The growing interest in Kv7.2/7.3 agonists originates from the involvement of these channels in several brain hyperexcitability disorders. In particular, Kv7.2/7.3 mutants have been clearly associated with epileptic encephalopathies (DEEs) as well as with a spectrum of focal epilepsy disorders, often associated with developmental plateauing or regression. Nevertheless, there is a lack of available therapeutic options, considering that retigabine, the only molecule used in clinic as a broad-spectrum Kv7 agonist, has been withdrawn from the market in late 2016. This is why several efforts have been made both by both academia and industry in the search for suitable chemotypes acting as Kv7.2/7.3 agonists. In this context, in silico methods have played a major role, since the precise structures of different Kv7 homotetramers have been only recently disclosed. In the present review, the computational methods used for the design of Kv.7.2/7.3 small molecule agonists and the underlying medicinal chemistry are discussed in the context of their biological and structure-function properties.
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Affiliation(s)
- Claudio Stagno
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Francesca Mancuso
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Tania Ciaglia
- Department of Pharmacy, University of Salerno, Via G. Paolo II, 84084 Fisciano, Italy
| | - Carmine Ostacolo
- Department of Pharmacy, University of Salerno, Via G. Paolo II, 84084 Fisciano, Italy
| | - Anna Piperno
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Nunzio Iraci
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
| | - Nicola Micale
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy
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4
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Rönnelid O, Elinder F. Carboxyl-group compounds activate voltage-gated potassium channels via a distinct mechanism. J Gen Physiol 2024; 156:e202313516. [PMID: 38832889 PMCID: PMC11148469 DOI: 10.1085/jgp.202313516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/14/2024] [Accepted: 05/21/2024] [Indexed: 06/06/2024] Open
Abstract
Voltage-gated ion channels are responsible for the electrical excitability of neurons and cardiomyocytes. Thus, they are obvious targets for pharmaceuticals aimed to modulate excitability. Compounds activating voltage-gated potassium (KV) channels are expected to reduce excitability. To search for new KV-channel activators, we performed a high-throughput screen of 10,000 compounds on a specially designed Shaker KV channel. Here, we report on a large family of channel-activating compounds with a carboxyl (COOH) group as the common motif. The most potent COOH activators are lipophilic (4 < LogP <7) and are suggested to bind at the interface between the lipid bilayer and the channel's positively charged voltage sensor. The negatively charged form of the COOH-group compounds is suggested to open the channel by electrostatically pulling the voltage sensor to an activated state. Several of the COOH-group compounds also activate the therapeutically important KV7.2/7.3 channel and can thus potentially be developed into antiseizure drugs. The COOH-group compounds identified in this study are suggested to act via the same site and mechanism of action as previously studied COOH-group compounds, such as polyunsaturated fatty acids and resin acids, but distinct from sites for several other types of potassium channel-activating compounds.
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Affiliation(s)
- Olle Rönnelid
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Fredrik Elinder
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
- Science for Life Laboratory, Linköping University, Linköping, Sweden
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5
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Krüger J, Lerche H. Retigabine and gabapentin restore channel function and neuronal firing in a cellular model of an epilepsy-associated dominant-negative KCNQ5 variant. Neuropharmacology 2024; 250:109892. [PMID: 38428481 DOI: 10.1016/j.neuropharm.2024.109892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/19/2024] [Accepted: 02/26/2024] [Indexed: 03/03/2024]
Abstract
KCNQ5 encodes the voltage-gated potassium channel KV7.5, a member of the KV7 channel family, which conducts the M-current. This current is a potent regulator of neuronal excitability by regulating membrane potential in the subthreshold range of action potentials and mediating the medium and slow afterhyperpolarization. Recently, we have identified five loss-of-function variants in KCNQ5 in patients with genetic generalized epilepsy. Using the most severe dominant-negative variant (R359C), we set out to investigate pharmacological therapeutic intervention by KV7 channel openers on channel function and neuronal firing. Retigabine and gabapentin increased R359C-derived M-current amplitudes in HEK cells expressing homomeric or heteromeric mutant KV7.5 channels. Retigabine was most effective in restoring K+ currents. Ten μM retigabine was sufficient to reach the level of WT currents without retigabine, whereas 100 μM of gabapentin showed less than half of this effect and application of 50 μM ZnCl2 only significantly increased M-current amplitude in heteromeric channels. Overexpression of KV7.5-WT potently inhibited neuronal firing by increasing the M-current, whereas R359C overexpression had the opposite effect and additionally decreased the medium afterhyperpolarization current. Both aforementioned drugs and Zn2+ reversed the effect of R359C expression by reducing firing to nearly normal levels at high current injections. Our study shows that a dominant-negative variant with a complete loss-of-function in KV7.5 leads to largely increased neuronal firing which may explain a neuronal hyperexcitability in patients. KV7 channel openers, such as retigabine or gabapentin, could be treatment options for patients currently displaying pharmacoresistant epilepsy and carrying loss-of-function variants in KCNQ5.
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Affiliation(s)
- Johanna Krüger
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 27, 72076, Tübingen, Germany.
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 27, 72076, Tübingen, Germany.
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6
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Huang Y, Ma D, Yang Z, Zhao Y, Guo J. Voltage-gated potassium channels KCNQs: Structures, mechanisms, and modulations. Biochem Biophys Res Commun 2023; 689:149218. [PMID: 37976835 DOI: 10.1016/j.bbrc.2023.149218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/19/2023]
Abstract
KCNQ (Kv7) channels are voltage-gated, phosphatidylinositol 4,5-bisphosphate- (PIP2-) modulated potassium channels that play essential roles in regulating the activity of neurons and cardiac myocytes. Hundreds of mutations in KCNQ channels are closely related to various cardiac and neurological disorders, such as long QT syndrome, epilepsy, and deafness, which makes KCNQ channels important drug targets. During the past several years, the application of single-particle cryo-electron microscopy (cryo-EM) technique in the structure determination of KCNQ channels has greatly advanced our understanding of their molecular mechanisms. In this review, we summarize the currently available structures of KCNQ channels, analyze their special voltage gating mechanism, and discuss their activation mechanisms by both the endogenous membrane lipid and the exogenous synthetic ligands. These structural studies of KCNQ channels will guide the development of drugs targeting KCNQ channels.
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Affiliation(s)
- Yuan Huang
- Department of Cardiology, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Demin Ma
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Zhenni Yang
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yiwen Zhao
- The Key Laboratory of Neural and Vascular Biology, The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Ministry of Education, Hebei Medical University, Shijiazhuang, 050011, China
| | - Jiangtao Guo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China.
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7
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Pökl M, Sridhar A, Frampton DJA, Linhart VA, Delemotte L, Liin SI. Subtype-specific modulation of human K V 7 channels by the anticonvulsant cannabidiol through a lipid-exposed pore-domain site. Br J Pharmacol 2023; 180:2956-2972. [PMID: 37377025 DOI: 10.1111/bph.16183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/16/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND AND PURPOSE Cannabidiol (CBD) is used clinically as an anticonvulsant. Its precise mechanism of action has remained unclear. CBD was recently demonstrated to enhance the activity of the neuronal KV 7.2/7.3 channel, which may be one important contributor to CBD anticonvulsant effect. Curiously, CBD inhibits the closely related cardiac KV 7.1/KCNE1 channel. Whether and how CBD affects other KV 7 subtypes remains uninvestigated and the CBD interaction sites mediating these diverse effects remain unknown. EXPERIMENTAL APPROACH Here, we used electrophysiology, molecular dynamics simulations, molecular docking and site-directed mutagenesis to address these questions. KEY RESULTS We found that CBD modulates the activity of all human KV 7 subtypes and that the effects are subtype dependent. CBD enhanced the activity of KV 7.2-7.5 subtypes, seen as a V50 shift towards more negative voltages or increased maximum conductance. In contrast, CBD inhibited the KV 7.1 and KV 7.1/KCNE1 channels, seen as a V50 shift towards more positive voltages and reduced conductance. In KV 7.2 and KV 7.4, we propose a CBD interaction site at the subunit interface in the pore domain that overlaps with the interaction site of other compounds, notably the anticonvulsant retigabine. However, CBD relies on other residues for its effects than the conserved tryptophan that is critical for retigabine effects. We propose a similar, though not identical CBD site in KV 7.1, with a non-conserved phenylalanine being important. CONCLUSIONS AND IMPLICATIONS We identify novel targets of CBD, contributing to a better understanding of CBD clinical effects and provide mechanistic insights into how CBD modulates different KV 7 subtypes.
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Affiliation(s)
- Michael Pökl
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Akshay Sridhar
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - Damon J A Frampton
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Veronika A Linhart
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Lucie Delemotte
- Department of Applied Physics, Science for Life Laboratory, KTH Royal Institute of Technology, Solna, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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8
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Villegas-Esguevillas M, Cho S, Vera-Zambrano A, Kwon JW, Barreira B, Telli G, Navarro-Dorado J, Morales-Cano D, de Olaiz B, Moreno L, Greenwood I, Pérez-Vizcaíno F, Kim SJ, Climent B, Cogolludo A. The novel K V7 channel activator URO-K10 exerts enhanced pulmonary vascular effects independent of the KCNE4 regulatory subunit. Biomed Pharmacother 2023; 164:114952. [PMID: 37295249 DOI: 10.1016/j.biopha.2023.114952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/23/2023] [Accepted: 05/27/2023] [Indexed: 06/12/2023] Open
Abstract
KV7 channels exert a pivotal role regulating vascular tone in several vascular beds. In this context, KV7 channel agonists represent an attractive strategy for the treatment of pulmonary arterial hypertension (PAH). Therefore, in this study, we have explored the pulmonary vascular effects of the novel KV7 channel agonist URO-K10. Consequently, the vasodilator and electrophysiological effects of URO-K10 were tested in rat and human pulmonary arteries (PA) and PA smooth muscle cells (PASMC) using myography and patch-clamp techniques. Protein expression was also determined by Western blot. Morpholino-induced knockdown of KCNE4 was assessed in isolated PA. PASMC proliferation was measured by BrdU incorporation assay. In summary, our data show that URO-K10 is a more effective relaxant of PA than the classical KV7 activators retigabine and flupirtine. URO-K10 enhanced KV currents in PASMC and its electrophysiological and relaxant effects were inhibited by the KV7 channel blocker XE991. The effects of URO-K10 were confirmed in human PA. URO-K10 also exhibited antiproliferative effects in human PASMC. Unlike retigabine and flupirtine, URO-K10-induced pulmonary vasodilation was not affected by morpholino-induced knockdown of the KCNE4 regulatory subunit. Noteworthy, the pulmonary vasodilator efficacy of this compound was considerably increased under conditions mimicking the ionic remodelling (as an in vitro model of PAH) and in PA from monocrotaline-induced pulmonary hypertensive rats. Taking all together, URO-K10 behaves as a KCNE4-independent KV7 channel activator with much increased pulmonary vascular effects compared to classical KV7 channel activators. Our study identifies a promising new drug in the context of PAH.
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Affiliation(s)
- Marta Villegas-Esguevillas
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain; CIBER Enfermedades Respiratorias (Ciberes), Madrid, Spain
| | - Suhan Cho
- Department of Physiology, College of Medicine, Seoul National University, Seoul, South Korea
| | - Alba Vera-Zambrano
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain; CIBER Enfermedades Respiratorias (Ciberes), Madrid, Spain
| | - Jae Won Kwon
- Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain
| | - Bianca Barreira
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain; CIBER Enfermedades Respiratorias (Ciberes), Madrid, Spain
| | - Göcken Telli
- Department of Pharmacology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
| | - Jorge Navarro-Dorado
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain
| | - Daniel Morales-Cano
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain; CIBER Enfermedades Respiratorias (Ciberes), Madrid, Spain
| | - Beatriz de Olaiz
- Department of Thoracic Surgery, Hospital Universitario de Getafe, Getafe, Spain
| | - Laura Moreno
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain; CIBER Enfermedades Respiratorias (Ciberes), Madrid, Spain
| | - Iain Greenwood
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, United Kingdom
| | - Francisco Pérez-Vizcaíno
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain; CIBER Enfermedades Respiratorias (Ciberes), Madrid, Spain
| | - Sung Joon Kim
- Department of Physiology, College of Medicine, Seoul National University, Seoul, South Korea
| | - Belén Climent
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
| | - Angel Cogolludo
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, Madrid, Spain; Institute of Health Research Gregorio Marañón (IiSGM), Madrid, Spain; CIBER Enfermedades Respiratorias (Ciberes), Madrid, Spain
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9
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Yang GM, Tian FY, Shen YW, Yang CY, Yuan H, Li P, Gao ZB. Functional characterization and in vitro pharmacological rescue of KCNQ2 pore mutations associated with epileptic encephalopathy. Acta Pharmacol Sin 2023; 44:1589-1599. [PMID: 36932231 PMCID: PMC10374643 DOI: 10.1038/s41401-023-01073-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 02/26/2023] [Indexed: 03/19/2023] Open
Abstract
Mutations in the KCNQ2 gene encoding KV7.2 subunit that mediates neuronal M-current cause a severe form of developmental and epileptic encephalopathy (DEE). Electrophysiological evaluation of KCNQ2 mutations has been proved clinically useful in improving outcome prediction and choosing rational anti-seizure medications (ASMs). In this study we described the clinical characteristics, electrophysiological phenotypes and the in vitro response to KCNQ openers of five KCNQ2 pore mutations (V250A, N258Y, H260P, A265T and G290S) from seven patients diagnosed with KCNQ2-DEE. The KCNQ2 variants were transfected into Chinese hamster ovary (CHO) cells alone, in combination with KCNQ3 (1:1) or with wild-type KCNQ2 (KCNQ2-WT) and KCNQ3 in a ratio of 1:1:2, respectively. Their expression and electrophysiological function were assessed. When transfected alone or in combination with KCNQ3, none of these mutations affected the membrane expression of KCNQ2, but most failed to induce a potassium current except A265T, in which trace currents were observed when co-transfected with KCNQ3. When co-expressed with KCNQ2-WT and KCNQ3 (1:1:2), the currents at 0 mV of these mutations were decreased by 30%-70% compared to the KCNQ2/3 channel, which could be significantly rescued by applying KCNQ openers including the approved antiepileptic drug retigabine (RTG, 10 μM), as well as two candidates subjected to clinical trials, pynegabine (HN37, 1 μM) and XEN1101 (1 μM). These newly identified pathologic variants enrich the KCNQ2-DEE mutation hotspots in the pore-forming domain. This electrophysiological study provides a rational basis for personalized therapy with KCNQ openers in DEE patients carrying loss-of-function (LOF) mutations in KCNQ2.
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Affiliation(s)
- Gui-Mei Yang
- School of Pharmacy, Zunyi Medical University, Zunyi, 563000, China
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, 528400, China
| | - Fu-Yun Tian
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, 528400, China.
- Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
| | - Yan-Wen Shen
- Department of Pediatrics, The First Medical Center of PLA General Hospital, Beijing, 100853, China
- Department of Pediatric neurology, Children's Hospital of Fudan university at Xiamen, Xiamen, 361006, China
| | - Chuan-Yan Yang
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, 528400, China
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, 211198, China
| | - Hui Yuan
- School of Pharmacy, Zunyi Medical University, Zunyi, 563000, China
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, 528400, China
| | - Ping Li
- School of Pharmacy, Zunyi Medical University, Zunyi, 563000, China.
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, 528400, China.
- Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China.
| | - Zhao-Bing Gao
- School of Pharmacy, Zunyi Medical University, Zunyi, 563000, China.
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan, 528400, China.
- Center for Neurological and Psychiatric Research and Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, 510515, China.
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10
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Manville RW, Hogenkamp D, Abbott GW. Ancient medicinal plant rosemary contains a highly efficacious and isoform-selective KCNQ potassium channel opener. Commun Biol 2023; 6:644. [PMID: 37322081 PMCID: PMC10272180 DOI: 10.1038/s42003-023-05021-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 06/06/2023] [Indexed: 06/17/2023] Open
Abstract
Voltage-gated potassium (Kv) channels in the KCNQ subfamily serve essential roles in the nervous system, heart, muscle and epithelia. Different heteromeric KCNQ complexes likely serve distinct functions in the brain but heteromer subtype-specific small molecules for research or therapy are lacking. Rosemary (Salvia rosmarinus) is an evergreen plant used medicinally for millennia for neurological and other disorders. Here, we report that rosemary extract is a highly efficacious opener of heteromeric KCNQ3/5 channels, with weak effects on KCNQ2/3. Using functional screening we find that carnosic acid, a phenolic diterpene from rosemary, is a potent, highly efficacious, PIP2 depletion-resistant KCNQ3 opener with lesser effects on KCNQ5 and none on KCNQ1 or KCNQ2. Carnosic acid is also highly selective for KCNQ3/5 over KCNQ2/3 heteromers. Medicinal chemistry, in silico docking, and mutagenesis reveal that carboxylate-guanidinium ionic bonding with an S4-5 linker arginine underlies the KCNQ3 opening proficiency of carnosic acid, the effects of which on KCNQ3/5 suggest unique therapeutic potential and a molecular basis for ancient neurotherapeutic use of rosemary.
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Affiliation(s)
- Rían W Manville
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Derk Hogenkamp
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA.
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11
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Chen KJ, Yoshimura R, Edmundo CA, Truong TM, Civelli O, Alachkar A, Abbott GW. Behavioral and neuro-functional consequences of eliminating the KCNQ3 GABA binding site in mice. Front Mol Neurosci 2023; 16:1192628. [PMID: 37305551 PMCID: PMC10248464 DOI: 10.3389/fnmol.2023.1192628] [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: 03/23/2023] [Accepted: 05/09/2023] [Indexed: 06/13/2023] Open
Abstract
Voltage-gated potassium (Kv) channels formed by α subunits KCNQ2-5 are important in regulating neuronal excitability. We previously found that GABA directly binds to and activates channels containing KCNQ3, challenging the traditional understanding of inhibitory neurotransmission. To investigate the functional significance and behavioral role of this direct interaction, mice with a mutated KCNQ3 GABA binding site (Kcnq3-W266L) were generated and subjected to behavioral studies. Kcnq3-W266L mice exhibited distinctive behavioral phenotypes, of which reduced nociceptive and stress responses were profound and sex-specific. In female Kcnq3-W266L mice, the phenotype was shifted towards more nociceptive effects, while in male Kcnq3-W266L mice, it was shifted towards the stress response. In addition, female Kcnq3-W266L mice exhibited lower motor activity and reduced working spatial memory. The neuronal activity in the lateral habenula and visual cortex was altered in the female Kcnq3-W266L mice, suggesting that GABAergic activation of KCNQ3 in these regions may play a role in the regulation of the responses. Given the known overlap between the nociceptive and stress brain circuits, our data provide new insights into a sex-dependent role of KCNQ3 in regulating neural circuits involved in nociception and stress, via its GABA binding site. These findings identify new targets for effective treatments for neurological and psychiatric conditions such as pain and anxiety.
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Affiliation(s)
- Kiki J. Chen
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
| | - Ryan Yoshimura
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Clarissa Adriana Edmundo
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
| | - Tri Minh Truong
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
| | - Olivier Civelli
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
| | - Amal Alachkar
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
- UC Irvine Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, United States
- Institute for Genomics and Bioinformatics, School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, United States
| | - Geoffrey W. Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
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12
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Kanyo R, Lamothe SM, Urrutia A, Goodchild SJ, Allison WT, Dean R, Kurata HT. Site and Mechanism of ML252 Inhibition of Kv7 Voltage-Gated Potassium Channels. FUNCTION 2023; 4:zqad021. [PMID: 37342413 PMCID: PMC10278987 DOI: 10.1093/function/zqad021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 04/27/2023] [Accepted: 04/28/2023] [Indexed: 06/22/2023] Open
Abstract
Kv7 (KCNQ) voltage-gated potassium channels are critical regulators of neuronal excitability and are candidate targets for development of antiseizure medications. Drug discovery efforts have identified small molecules that modulate channel function and reveal mechanistic insights into Kv7 channel physiological roles. While Kv7 channel activators have therapeutic benefits, inhibitors are useful for understanding channel function and mechanistic validation of candidate drugs. In this study, we reveal the mechanism of a Kv7.2/Kv7.3 inhibitor, ML252. We used docking and electrophysiology to identify critical residues involved in ML252 sensitivity. Most notably, Kv7.2[W236F] or Kv7.3[W265F] mutations strongly attenuate ML252 sensitivity. This tryptophan residue in the pore is also required for sensitivity to certain activators, including retigabine and ML213. We used automated planar patch clamp electrophysiology to assess competitive interactions between ML252 and different Kv7 activator subtypes. A pore-targeted activator (ML213) weakens the inhibitory effects of ML252, whereas a distinct activator subtype (ICA-069673) that targets the voltage sensor does not prevent ML252 inhibition. Using transgenic zebrafish larvae expressing an optical reporter (CaMPARI) to measure neural activity in-vivo, we demonstrate that Kv7 inhibition by ML252 increases neuronal excitability. Consistent with in-vitro data, ML213 suppresses ML252 induced neuronal activity, while the voltage-sensor targeted activator ICA-069673 does not prevent ML252 actions. In summary, this study establishes a binding site and mechanism of action of ML252, classifying this poorly understood drug as a pore-targeted Kv7 channel inhibitor that binds to the same tryptophan residue as commonly used pore-targeted Kv7 activators. ML213 and ML252 likely have overlapping sites of interaction in the pore Kv7.2 and Kv7.3 channels, resulting in competitive interactions. In contrast, the VSD-targeted activator ICA-069673 does not prevent channel inhibition by ML252.
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Affiliation(s)
- Richard Kanyo
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, 9-70 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada
| | - Shawn M Lamothe
- Dept. of Pharmacology, Alberta Diabetes Institute, University of Alberta, 9-70 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada
| | - Arturo Urrutia
- Dept. of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
| | - Samuel J Goodchild
- Dept. of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
| | - W Ted Allison
- Dept. of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Richard Dean
- Dept. of Cellular and Molecular Biology, Xenon Pharmaceuticals Inc., 3650 Gilmore Way, Burnaby, BC V5G 4W8, Canada
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13
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Oh KS, Roh JW, Joo SY, Ryu K, Kim JA, Kim SJ, Jang SH, Koh YI, Kim DH, Kim HY, Choi M, Jung J, Namkung W, Nam JH, Choi JY, Gee HY. Overlooked KCNQ4 variants augment the risk of hearing loss. Exp Mol Med 2023; 55:844-859. [PMID: 37009795 PMCID: PMC10167218 DOI: 10.1038/s12276-023-00976-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/28/2022] [Accepted: 01/17/2023] [Indexed: 04/04/2023] Open
Abstract
Pathogenic variants of KCNQ4 cause symmetrical, late-onset, progressive, high-frequency-affected hearing loss, which eventually involves all frequencies with age. To understand the contribution of KCNQ4 variants to hearing loss, we analyzed whole-exome and genome sequencing data from patients with hearing loss and individuals whose hearing phenotypes were unknown. In KCNQ4, we identified seven missense variants and one deletion variant in 9 hearing loss patients and 14 missense variants in the Korean population with an unknown hearing loss phenotype. The p.R420W and p.R447W variants were found in both cohorts. To investigate the effects of these variants on KCNQ4 function, we performed whole-cell patch clamping and examined their expression levels. Except for p.G435Afs*61, all KCNQ4 variants exhibited normal expression patterns similar to those of wild-type KCNQ4. The p.R331Q, p.R331W, p.G435Afs*61, and p.S691G variants, which were identified in patients with hearing loss, showed a potassium (K+) current density lower than or similar to that of p.L47P, a previously reported pathogenic variant. The p.S185W and p.R216H variants shifted the activation voltage to hyperpolarized voltages. The channel activity of the p.S185W, p.R216H, p.V672M, and p.S691G KCNQ4 proteins was rescued by the KCNQ activators retigabine or zinc pyrithione, whereas p.G435Afs*61 KCNQ4 proteins were partially rescued by sodium butyrate, a chemical chaperone. Additionally, the structure of the variants predicted using AlphaFold2 showed impaired pore configurations, as did the patch-clamp data. Our findings suggest that KCNQ4 variants may be overlooked in hearing loss that starts in adulthood. Some of these variants are medically treatable; hence, genetic screening for KCNQ4 is important.
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Affiliation(s)
- Kyung Seok Oh
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Jae Won Roh
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Sun Young Joo
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Kunhi Ryu
- Yonsei University College of Pharmacy, Incheon, 21983, Republic of Korea
| | - Jung Ah Kim
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Se Jin Kim
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Seung Hyun Jang
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Young Ik Koh
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Da Hye Kim
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Hye-Youn Kim
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea
| | - Murim Choi
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Jinsei Jung
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Wan Namkung
- Yonsei University College of Pharmacy, Incheon, 21983, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, Gyeongju, 38066, Republic of Korea.
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Gyeonggi-do, 10326, Republic of Korea.
| | - Jae Young Choi
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea.
| | - Heon Yung Gee
- Department of Pharmacology, Graduate School of Medical Science, Yonsei University College of Medicine, Brain Korea 21 Project, Seoul, 03722, Republic of Korea.
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14
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Wurm KW, Bartz FM, Schulig L, Bodtke A, Bednarski PJ, Link A. Replacing the oxidation-sensitive triaminoaryl chemotype of problematic K V 7 channel openers: Exploration of a nicotinamide scaffold. Arch Pharm (Weinheim) 2023; 356:e2200473. [PMID: 36395379 DOI: 10.1002/ardp.202200473] [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: 09/08/2022] [Revised: 10/13/2022] [Accepted: 10/18/2022] [Indexed: 11/18/2022]
Abstract
KV 7 channel openers have proven their therapeutic value in the treatment of pain as well as epilepsy and, moreover, they hold the potential to expand into additional indications with unmet medical needs. However, the clinically validated but meanwhile discontinued KV 7 channel openers flupirtine and retigabine bear an oxidation-sensitive triaminoraryl scaffold, which is suspected of causing adverse drug reactions via the formation of quinoid oxidation products. Here, we report the design and synthesis of nicotinamide analogs and related compounds that remediate the liability in the chemical structure of flupirtine and retigabine. Optimization of a nicotinamide lead structure yielded analogs with excellent KV 7.2/3 opening activity, as evidenced by EC50 values approaching the single-digit nanomolar range. On the other hand, weighted KV 7.2/3 opening activity data including inactive compounds allowed for the establishment of structure-activity relationships and a plausible binding mode hypothesis verified by docking and molecular dynamics simulations.
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Affiliation(s)
- Konrad W Wurm
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Frieda-Marie Bartz
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Lukas Schulig
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Anja Bodtke
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Patrick J Bednarski
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Andreas Link
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
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15
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Jeong DJ, Kim KW, Suh BC. Dual regulation of Kv7.2/7.3 channels by long-chain n-alcohols. J Gen Physiol 2022; 155:213769. [PMID: 36534082 PMCID: PMC9767652 DOI: 10.1085/jgp.202213191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 10/31/2022] [Accepted: 12/02/2022] [Indexed: 12/23/2022] Open
Abstract
Normal alcohols (n-alcohols) can induce anesthetic effects by acting on neuronal ion channels. Recent studies have revealed the effects of n-alcohols on various ion channels; however, the underlying molecular mechanisms remain unclear. Here, we provide evidence that long-chain n-alcohols have dual effects on Kv7.2/7.3 channels, resulting in channel activation as the net effect. Using heterologous expression systems, we found that n-alcohols could differentially regulate the Kv7.2/7.3 channel depending on their chain length. Treatment with short-chain ethanol and propanol diminished Kv7.2/7.3 currents, whereas treatment with long-chain hexanol and octanol enhanced the currents. However, the long-chain alcohols failed to potentiate Kv7.2 currents pre-activated by retigabine. Instead, they inhibited the currents, similar to short-chain ethanol. The stimulatory effect of the long-chain n-alcohols was also converted into an inhibitory one in the mutant Kv7.2(W236L) channels, while the inhibitory effect of ethanol did not differ between wild-type Kv7.2 and mutant Kv7.2(W236L). The inhibition of currents by n-alcohols was also seen in Kv7.1 channel which does not have the tryptophan (W) residue in S5. These findings suggest that long-chain n-alcohols exhibit dual effects through independent working sites on the Kv7.2 channel. Finally, we confirmed that the hydroxyl group with a negative electrostatic potential surface is essential for the dual actions of n-alcohol. Together, our data suggest that long-chain n-alcohols regulate Kv7.2/7.3 channels by interacting with both stimulatory and inhibitory sites and that their stimulatory action depends on the conserved tryptophan 236 residue in S5 and could be important for triggering their anesthetic effects.
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Affiliation(s)
- Da-Jeong Jeong
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
| | - Kwon-Woo Kim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea
| | - Byung-Chang Suh
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea,Correspondence to Byung-Chang Suh:
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16
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Combinations of classical and non-classical voltage dependent potassium channel openers suppress nociceptor discharge and reverse chronic pain signs in a rat model of Gulf War illness. Neurotoxicology 2022; 93:186-199. [PMID: 36216193 DOI: 10.1016/j.neuro.2022.10.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/27/2022] [Accepted: 10/05/2022] [Indexed: 11/15/2022]
Abstract
In a companion paper we examined whether combinations of Kv7 channel openers (Retigabine and Diclofenac; RET, DIC) could be effective modifiers of deep tissue nociceptor activity; and whether such combinations could then be optimized for use as safe analgesics for pain-like signs that developed in a rat model of GWI (Gulf War Illness) pain. In the present report, we examined the combinations of Retigabine/Meclofenamate (RET/MEC) and Meclofenamate/Diclofenac (MEC/DIC). Voltage clamp experiments were performed on deep tissue nociceptors isolated from rat DRG (dorsal root ganglion). In voltage clamp studies, a stepped voltage protocol was applied (-55 to -40 mV; Vh=-60 mV; 1500 msec) and Kv7 evoked currents were subsequently isolated by Linopirdine subtraction. MEC greatly enhanced voltage dependent conductance and produced exceptional maximum sustained currents of 6.01 ± 0.26 pA/pF (EC50: 62.2 ± 8.99 μM). Combinations of RET/MEC, and MEC/DIC substantially amplified resting currents at low concentrations. MEC/DIC also greatly improved voltage dependent conductance. In current clamp experiments, a cholinergic challenge test (Oxotremorine-M, 10 μM; OXO), associated with our GWI rat model, produced powerful action potential (AP) bursts (85 APs). Optimized combinations of RET/MEC (5 and 0.5 μM) and MEC/DIC (0.5 and 2.5 μM) significantly reduced AP discharges to 3 and 7 Aps, respectively. Treatment of pain-like ambulatory behavior in our rat model with a RET/MEC combination (5 and 0.5 mg/kg) successfully rescued ambulation deficits, but could not be fully separated from the effect of RET alone. Further development of this approach is recommended.
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17
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Musella S, Carotenuto L, Iraci N, Baroli G, Ciaglia T, Nappi P, Basilicata MG, Salviati E, Barrese V, Vestuto V, Pignataro G, Pepe G, Sommella E, Di Sarno V, Manfra M, Campiglia P, Gomez-Monterrey I, Bertamino A, Taglialatela M, Ostacolo C, Miceli F. Beyond Retigabine: Design, Synthesis, and Pharmacological Characterization of a Potent and Chemically Stable Neuronal Kv7 Channel Activator with Anticonvulsant Activity. J Med Chem 2022; 65:11340-11364. [PMID: 35972998 PMCID: PMC9421656 DOI: 10.1021/acs.jmedchem.2c00911] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
![]()
Neuronal Kv7 channels represent important pharmacological
targets
for hyperexcitability disorders including epilepsy. Retigabine is
the prototype Kv7 activator clinically approved for seizure treatment;
however, severe side effects associated with long-term use have led
to its market discontinuation. Building upon the recently described
cryoEM structure of Kv7.2 complexed with retigabine and on previous
structure–activity relationship studies, a small library of
retigabine analogues has been designed, synthesized, and characterized
for their Kv7 opening ability using both fluorescence- and electrophysiology-based
assays. Among all tested compounds, 60 emerged as a potent
and photochemically stable neuronal Kv7 channel activator. Compared
to retigabine, compound 60 displayed a higher brain/plasma
distribution ratio, a longer elimination half-life, and more potent
and effective anticonvulsant effects in an acute seizure model in
mice. Collectively, these data highlight compound 60 as
a promising lead compound for the development of novel Kv7 activators
for the treatment of hyperexcitability diseases.
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Affiliation(s)
- Simona Musella
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Lidia Carotenuto
- Department of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via Pansini, 5, Naples 80131, Italy
| | - Nunzio Iraci
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences (CHIBIOFARAM), University of Messina, Viale Ferdinando Stagno d'Alcontres 31, Messina 98166, Italy
| | - Giulia Baroli
- Department of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via Pansini, 5, Naples 80131, Italy
| | - Tania Ciaglia
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Piera Nappi
- Department of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via Pansini, 5, Naples 80131, Italy
| | | | - Emanuela Salviati
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Vincenzo Barrese
- Department of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via Pansini, 5, Naples 80131, Italy
| | - Vincenzo Vestuto
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Giuseppe Pignataro
- Department of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via Pansini, 5, Naples 80131, Italy
| | - Giacomo Pepe
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Eduardo Sommella
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Veronica Di Sarno
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Michele Manfra
- Department of Science, University of Basilicata, Via dell'Ateneo Lucano 10, Potenza 85100, Italy
| | - Pietro Campiglia
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Isabel Gomez-Monterrey
- Department of Pharmacy, University Federico II of Naples, Via D. Montesano 49, Naples 80131, Italy
| | - Alessia Bertamino
- Department of Pharmacy, University of Salerno, Via G. Paolo II 132, Fisciano 84084, Salerno, Italy
| | - Maurizio Taglialatela
- Department of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via Pansini, 5, Naples 80131, Italy
| | - Carmine Ostacolo
- Department of Pharmacy, University Federico II of Naples, Via D. Montesano 49, Naples 80131, Italy
| | - Francesco Miceli
- Department of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via Pansini, 5, Naples 80131, Italy
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18
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Yang ND, Kanyo R, Zhao L, Li J, Kang PW, Dou AK, White KM, Shi J, Nerbonne JM, Kurata HT, Cui J. Electro-mechanical coupling of KCNQ channels is a target of epilepsy-associated mutations and retigabine. SCIENCE ADVANCES 2022; 8:eabo3625. [PMID: 35857840 PMCID: PMC9299555 DOI: 10.1126/sciadv.abo3625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
KCNQ2 and KCNQ3 form the M-channels that are important in regulating neuronal excitability. Inherited mutations that alter voltage-dependent gating of M-channels are associated with neonatal epilepsy. In the homolog KCNQ1 channel, two steps of voltage sensor activation lead to two functionally distinct open states, the intermediate-open (IO) and activated-open (AO), which define the gating, physiological, and pharmacological properties of KCNQ1. However, whether the M-channel shares the same mechanism is unclear. Here, we show that KCNQ2 and KCNQ3 feature only a single conductive AO state but with a conserved mechanism for the electro-mechanical (E-M) coupling between voltage sensor activation and pore opening. We identified some epilepsy-linked mutations in KCNQ2 and KCNQ3 that disrupt E-M coupling. The antiepileptic drug retigabine rescued KCNQ3 currents that were abolished by a mutation disrupting E-M coupling, suggesting that modulating the E-M coupling in KCNQ channels presents a potential strategy for antiepileptic therapy.
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Affiliation(s)
- Nien-Du Yang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Richard Kanyo
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Lu Zhao
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jingru Li
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Po Wei Kang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Alex Kelly Dou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Kelli McFarland White
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jeanne M. Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Harley T. Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
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19
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Specchio N, Pietrafusa N, Perucca E, Cross JH. New paradigms for the treatment of pediatric monogenic epilepsies: Progressing toward precision medicine. Epilepsy Behav 2022; 131:107961. [PMID: 33867301 DOI: 10.1016/j.yebeh.2021.107961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/25/2022]
Abstract
Despite the availability of 28 antiseizure medications (ASMs), one-third of people with epilepsy fail to achieve sustained freedom from seizures. Clinical outcome is even poorer for children with developmental and epileptic encephalopathies (DEEs), many of which are due to single-gene mutations. Discovery of causative genes, however, has paved the way to understanding the molecular mechanism underlying these epilepsies, and to the rational application, or development, of precision treatments aimed at correcting the specific functional defects or their consequences. This article provides an overview of current progress toward precision medicine (PM) in the management of monogenic pediatric epilepsies, by focusing on four different scenarios, namely (a) rational selection of ASMs targeting specifically the underlying pathogenetic mechanisms; (b) development of targeted therapies based on novel molecules; (c) use of dietary treatments or food constituents aimed at correcting specific metabolic defects; and (d) repurposing of medications originally approved for other indications. This article is part of the Special Issue "Severe Infantile Epilepsies".
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Affiliation(s)
- Nicola Specchio
- Rare and Complex Epilepsy Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy.
| | - Nicola Pietrafusa
- Rare and Complex Epilepsy Unit, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Full Member of European Reference Network EpiCARE, Rome, Italy
| | - Emilio Perucca
- Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy
| | - J Helen Cross
- UCL NIHR BRC Great Ormond Street Institute of Child Health and Great Ormond Street Hospital for Children, London, UK
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20
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Vanoye CG, Desai RR, Ji Z, Adusumilli S, Jairam N, Ghabra N, Joshi N, Fitch E, Helbig KL, McKnight D, Lindy AS, Zou F, Helbig I, Cooper EC, George AL. High-throughput evaluation of epilepsy-associated KCNQ2 variants reveals functional and pharmacological heterogeneity. JCI Insight 2022; 7:156314. [PMID: 35104249 PMCID: PMC8983144 DOI: 10.1172/jci.insight.156314] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hundreds of genetic variants in KCNQ2 encoding the voltage-gated potassium channel KV7.2 are associated with early onset epilepsy and/or developmental disability, but the functional consequences of most variants are unknown. Absent functional annotation for KCNQ2 variants hinders identification of individuals who may benefit from emerging precision therapies. We employed automated patch clamp recordings to assess at, to our knowledge, an unprecedented scale the functional and pharmacological properties of 79 missense and 2 inframe deletion KCNQ2 variants. Among the variants we studied were 18 known pathogenic variants, 24 mostly rare population variants, and 39 disease-associated variants with unclear functional effects. We analyzed electrophysiological data recorded from 9,480 cells. The functional properties of 18 known pathogenic variants largely matched previously published results and validated automated patch clamp for this purpose. Unlike rare population variants, most disease-associated KCNQ2 variants exhibited prominent loss-of-function with dominant-negative effects, providing strong evidence in support of pathogenicity. All variants responded to retigabine, although there were substantial differences in maximal responses. Our study demonstrated that dominant-negative loss-of-function is a common mechanism associated with missense KCNQ2 variants. Importantly, we observed genotype-dependent differences in the response of KCNQ2 variants to retigabine, a proposed precision therapy for KCNQ2 developmental and epileptic encephalopathy.
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Affiliation(s)
- Carlos G. Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Reshma R. Desai
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Zhigang Ji
- Departments of Neurology, Neuroscience, Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Sneha Adusumilli
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nirvani Jairam
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nora Ghabra
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nishtha Joshi
- Departments of Neurology, Neuroscience, Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Eryn Fitch
- The Epilepsy NeuroGenetics Initiative (ENGIN), and,Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Katherine L. Helbig
- The Epilepsy NeuroGenetics Initiative (ENGIN), and,Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | | | | | - Ingo Helbig
- The Epilepsy NeuroGenetics Initiative (ENGIN), and,Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Edward C. Cooper
- Departments of Neurology, Neuroscience, Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Alfred L. George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.,Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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21
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Abstract
Since prehistory, human species have depended on plants for both food and medicine. Even in countries with ready access to modern medicines, alternative treatments are still highly regarded and commonly used. Unlike modern pharmaceuticals, many botanical medicines are in widespread use despite a lack of safety and efficacy data derived from controlled clinical trials and often unclear mechanisms of action. Contributing to this are the complex and undefined composition and likely multifactorial mechanisms of action and multiple targets of many botanical medicines. Here, we review the newfound importance of the ubiquitous KCNQ subfamily of voltage-gated potassium channels as targets for botanical medicines, including basil, capers, cilantro, lavender, fennel, chamomile, ginger, and Camellia, Sophora, and Mallotus species. We discuss the implications for the traditional use of these plants for disorders such as seizures, hypertension, and diabetes and the molecular mechanisms of plant secondary metabolite effects on KCNQ channels.
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Affiliation(s)
- Kaitlyn E Redford
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California 92697, USA;
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California 92697, USA;
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22
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Development of KVO treatment strategies for chronic pain in a rat model of Gulf War Illness. Toxicol Appl Pharmacol 2022; 434:115821. [PMID: 34896435 DOI: 10.1016/j.taap.2021.115821] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/01/2021] [Accepted: 12/04/2021] [Indexed: 12/19/2022]
Abstract
We examined whether combinations of Kv7 channel openers could be effective modifiers of deep tissue nociceptor activity; and whether such combinations could then be optimized for use as safe analgesics for pain-like signs that developed in a rat model of GWI (Gulf War Illness) pain. Voltage clamp experiments were performed on subclassified nociceptors isolated from rat DRG (dorsal root ganglion). A stepped voltage protocol was applied (-55 to -40 mV; Vh = -60 mV; 1500 ms) and Kv7 evoked currents were subsequently isolated by linopirdine subtraction. Directly activated and voltage activated K+ currents were characterized in the presence and absence of Retigabine (5-100 μM) and/or Diclofenac (50-140 μM). Retigabine produced substantial voltage dependent effects and a maximal sustained current of 1.14 pA/pF ± 0.15 (ED50: 62.7 ± 3.18 μM). Diclofenac produced weak voltage dependent effects but a similar maximum sustained current of 1.01 ± 0.26 pA/pF (ED50: 93.2 ± 8.99 μM). Combinations of Retigabine and Diclofenac substantially amplified resting currents but had little effect on voltage dependence. Using a cholinergic challenge test (Oxotremorine, 10 μM) associated with our GWI rat model, combinations of Retigabine (5 uM) and Diclofenac (2.5, 20 and 50 μM) substantially reduced or totally abrogated action potential discharge to the cholinergic challenge. When combinations of Retigabine and Diclofenac were used to relieve pain-signs in our rat model of GWI, only those combinations associated with serious subacute side effects could relieve pain-like behaviors.
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23
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Abbott GW, Redford KE, Yoshimura RF, Manville RW, Moreira L, Tran K, Arena G, Kookootsedes A, Lasky E, Gunnison E. KCNQ and KCNE Isoform-Dependent Pharmacology Rationalizes Native American Dual Use of Specific Plants as Both Analgesics and Gastrointestinal Therapeutics. Front Physiol 2021; 12:777057. [PMID: 34858215 PMCID: PMC8632246 DOI: 10.3389/fphys.2021.777057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 10/14/2021] [Indexed: 12/12/2022] Open
Abstract
Indigenous peoples of the Americas are proficient in botanical medicine. KCNQ family voltage-gated potassium (Kv) channels are sensitive to a variety of ligands, including plant metabolites. Here, we screened methanolic extracts prepared from 40 Californian coastal redwood forest plants for effects on Kv current and membrane potential in Xenopus oocytes heterologously expressing KCNQ2/3, which regulates excitability of neurons, including those that sense pain. Extracts from 9 of the 40 plant species increased KCNQ2/3 current at –60 mV by ≥threefold (maximally, 15-fold by Urtica dioica) and/or hyperpolarized membrane potential by ≥-3 mV (maximally, –11 mV by Arctostaphylos glandulosa). All nine plants have traditionally been used as both analgesics and gastrointestinal therapeutics. Of two extracts tested, both acted as KCNQ-dependent analgesics in mice. KCNQ2/3 activation at physiologically relevant, subthreshold membrane potentials by tannic acid, gallic acid and quercetin provided molecular correlates for analgesic action of several of the plants. While tannic acid also activated KCNQ1 and KCNQ1-KCNE1 at hyperpolarized, negative membrane potentials, it inhibited KCNQ1-KCNE3 at both negative and positive membrane potentials, mechanistically rationalizing historical use of tannic acid-containing plants as gastrointestinal therapeutics. KCNE dependence of KCNQ channel modulation by plant metabolites therefore provides a molecular mechanistic basis for Native American use of specific plants as both analgesics and gastrointestinal aids.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Kaitlyn E Redford
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Ryan F Yoshimura
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Rían W Manville
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Luiz Moreira
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Kevin Tran
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Grey Arena
- Redwood Creek Vegetation Team, National Park Service, Sausalito, CA, United States
| | | | - Emma Lasky
- Redwood Creek Vegetation Team, National Park Service, Sausalito, CA, United States
| | - Elliot Gunnison
- Redwood Creek Vegetation Team, National Park Service, Sausalito, CA, United States
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24
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Progression of KCNQ4 related genetic hearing loss: a narrative review. JOURNAL OF BIO-X RESEARCH 2021. [DOI: 10.1097/jbr.0000000000000112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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25
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Larsson JE, Karlsson U, Wu X, Liin SI. Combining endocannabinoids with retigabine for enhanced M-channel effect and improved KV7 subtype selectivity. J Gen Physiol 2021; 152:151732. [PMID: 32365171 PMCID: PMC7398146 DOI: 10.1085/jgp.202012576] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/25/2020] [Indexed: 12/22/2022] Open
Abstract
Retigabine is unique among anticonvulsant drugs by targeting the neuronal M-channel, which is composed of KV7.2/KV7.3 and contributes to the negative neuronal resting membrane potential. Unfortunately, retigabine causes adverse effects, which limits its clinical use. Adverse effects may be reduced by developing M-channel activators with improved KV7 subtype selectivity. The aim of this study was to evaluate the prospect of endocannabinoids as M-channel activators, either in isolation or combined with retigabine. Human KV7 channels were expressed in Xenopus laevis oocytes. The effect of extracellular application of compounds with different properties was studied using two-electrode voltage clamp electrophysiology. Site-directed mutagenesis was used to construct channels with mutated residues to aid in the mechanistic understanding of these effects. We find that arachidonoyl-L-serine (ARA-S), a weak endocannabinoid, potently activates the human M-channel expressed in Xenopus oocytes. Importantly, we show that ARA-S activates the M-channel via a different mechanism and displays a different KV7 subtype selectivity compared with retigabine. We demonstrate that coapplication of ARA-S and retigabine at low concentrations retains the effect on the M-channel while limiting effects on other KV7 subtypes. Our findings suggest that improved KV7 subtype selectivity of M-channel activators can be achieved through strategically combining compounds with different subtype selectivity.
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Affiliation(s)
- Johan E Larsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Urban Karlsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Xiongyu Wu
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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26
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Naffaa MM, Al-Ewaidat OA. Ligand modulation of KCNQ-encoded (K V7) potassium channels in the heart and nervous system. Eur J Pharmacol 2021; 906:174278. [PMID: 34174270 DOI: 10.1016/j.ejphar.2021.174278] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/06/2021] [Accepted: 06/18/2021] [Indexed: 10/21/2022]
Abstract
KCNQ-encoded (KV7) potassium channels are diversely distributed in the human tissues, associated with many physiological processes and pathophysiological conditions. These channels are increasingly used as drug targets for treating diseases. More selective and potent molecules on various types of the KV7 channels are desirable for appropriate therapies. The recent knowledge of the structure and function of human KCNQ-encoded channels makes it more feasible to achieve these goals. This review discusses the role and mechanism of action of many molecules in modulating the function of the KCNQ-encoded potassium channels in the heart and nervous system. The effects of these compounds on KV7 channels help to understand their involvement in many diseases, and to search for more selective and potent ligands to be used in the treatment of many disorders such as various types of cardiac arrhythmias, epilepsy, and pain.
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Affiliation(s)
- Moawiah M Naffaa
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, 27710, USA; Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
| | - Ola A Al-Ewaidat
- Faculty of Medicine, The University of Jordan, Amman, 11942, Jordan
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27
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Ottosson NE, Silverå Ejneby M, Wu X, Estrada-Mondragón A, Nilsson M, Karlsson U, Schupp M, Rognant S, Jepps TA, Konradsson P, Elinder F. Synthetic resin acid derivatives selectively open the hK V 7.2/7.3 channel and prevent epileptic seizures. Epilepsia 2021; 62:1744-1758. [PMID: 34085706 DOI: 10.1111/epi.16932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/19/2021] [Accepted: 05/03/2021] [Indexed: 01/10/2023]
Abstract
OBJECTIVE About one third of all patients with epilepsy have pharmacoresistant seizures. Thus there is a need for better pharmacological treatments. The human voltage-gated potassium (hKV ) channel hKV 7.2/7.3 is a validated antiseizure target for compounds that activate this channel. In a previous study we have shown that resin acid derivatives can activate the hKV 7.2/7.3 channel. In this study we investigated if these channel activators have the potential to be developed into a new type of antiseizure drug. Thus we examined their structure-activity relationships and the site of action on the hKV 7.2/7.3 channel, if they have unwanted cardiac and cardiovascular effects, and their potential antiseizure effect. METHODS Ion channels were expressed in Xenopus oocytes or mammalian cell lines and explored with two-electrode voltage-clamp or automated patch-clamp techniques. Unwanted vascular side effects were investigated with isometric tension recordings. Antiseizure activity was studied in an electrophysiological zebrafish-larvae model. RESULTS Fourteen resin acid derivatives were tested on hKV 7.2/7.3. The most efficient channel activators were halogenated and had a permanently negatively charged sulfonyl group. The compounds did not bind to the sites of other hKV 7.2/7.3 channel activators, retigabine, or ICA-069673. Instead, they interacted with the most extracellular gating charge of the S4 voltage-sensing helix, and the effects are consistent with an electrostatic mechanism. The compounds altered the voltage dependence of hKV 7.4, but in contrast to retigabine, there were no effects on the maximum conductance. Consistent with these data, the compounds had less smooth muscle-relaxing effect than retigabine. The compounds had almost no effect on the voltage dependence of hKV 11.1, hNaV 1.5, or hCaV 1.2, or on the amplitude of hKV 11.1. Finally, several resin acid derivatives had clear antiseizure effects in a zebrafish-larvae model. SIGNIFICANCE The described resin acid derivatives hold promise for new antiseizure medications, with reduced risk for adverse effects compared with retigabine.
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Affiliation(s)
- Nina E Ottosson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Malin Silverå Ejneby
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Xiongyu Wu
- Department of Physics, Chemistry, and Biology, Linköping University, Linköping, Sweden
| | | | - Michelle Nilsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Urban Karlsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | | | - Salomé Rognant
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Andrew Jepps
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Peter Konradsson
- Department of Physics, Chemistry, and Biology, Linköping University, Linköping, Sweden
| | - Fredrik Elinder
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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28
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Wright AB, Sukhanova KY, Elmslie KS. K V7 channels are potential regulators of the exercise pressor reflex. J Neurophysiol 2021; 126:1-10. [PMID: 34038189 DOI: 10.1152/jn.00700.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The exercise pressor reflex (EPR) originates in skeletal muscle and is activated by exercise-induced signals to increase arterial blood pressure and cardiac output. Muscle ischemia can elicit the EPR, which can be inappropriately activated in patients with peripheral vascular disease or heart failure to increase the incidence of myocardial infarction. We seek to better understand the receptor/channels that control excitability of group III and group IV muscle afferent fibers that give rise to the EPR. Bradykinin (BK) is released within contracting muscle and can evoke the EPR. However, the mechanism is incompletely understood. KV7 channels strongly regulate neuronal excitability and are inhibited by BK. We have identified KV7 currents in muscle afferent neurons by their characteristic activation/deactivation kinetics, enhancement by the KV7 activator retigabine, and block by KV7 specific inhibitor XE991. The blocking of KV7 current by different XE991 concentrations suggests that the KV7 current is generated by both KV7.2/7.3 (high affinity) and KV7.5 (low affinity) channels. The KV7 current was inhibited by 300 nM BK in neurons with diameters consistent with both group III and group IV afferents. The inhibition of KV7 by BK could be a mechanism by which this metabolic mediator generates the EPR. Furthermore, our results suggest that KV7 channel activators such as retigabine, could be used to reduce cardiac stress resulting from the exacerbated EPR in patients with cardiovascular disease.NEW & NOTEWORTHY KV7 channels control neuronal excitability. We show that these channels are expressed in muscle afferents and generate currents that are blocked by XE991 and bradykinin (BK). The XE991 block suggests that KV7 current is generated by KV7.2/3 and KV7.5 channels. The BK inhibition of KV7 channels may explain how BK activates the exercise pressor reflex (EPR). Retigabine can enhance KV7 current, which could help control the inappropriately activated EPR in patients with cardiovascular disease.
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Affiliation(s)
- Andrew B Wright
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Khrystyna Yu Sukhanova
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
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29
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Varghese N, Lauritano A, Taglialatela M, Tzingounis AV. KCNQ3 is the principal target of retigabine in CA1 and subicular excitatory neurons. J Neurophysiol 2021; 125:1440-1449. [PMID: 33729829 DOI: 10.1152/jn.00564.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Retigabine is a first-in-class potassium channel opener approved for patients with epilepsy. Unfortunately, several side effects have limited its use in clinical practice, overshadowing its beneficial effects. Multiple studies have shown that retigabine acts by enhancing the activity of members of the voltage-gated KCNQ (Kv7) potassium channel family, particularly the neuronal KCNQ channels KCNQ2-KCNQ5. However, it is currently unknown whether retigabine's action in neurons is mediated by all KCNQ neuronal channels or by only a subset. This knowledge is necessary to elucidate retigabine's mechanism of action in the central nervous system and its adverse effects and to design more effective and selective retigabine analogs. In this study, we show that the action of retigabine in excitatory neurons strongly depends on the presence of KCNQ3 channels. Deletion of Kcnq3 severely limited the ability of retigabine to reduce neuronal excitability in mouse CA1 and subiculum excitatory neurons. In addition, we report that in the absence of KCNQ3 channels, retigabine can enhance CA1 pyramidal neuron activity, leading to a greater number of action potentials and reduced spike frequency adaptation; this finding further supports a key role of KCNQ3 channels in mediating the action of retigabine. Our work provides new insight into the action of retigabine in forebrain neurons, clarifying retigabine's action in the nervous system.NEW & NOTEWORTHY Retigabine has risen to prominence as a first-in-class potassium channel opener approved by the Food and Drug Administration, with potential for treating multiple neurological disorders. Here, we demonstrate that KCNQ3 channels are the primary target of retigabine in excitatory neurons, as deleting these channels greatly diminishes the effect of retigabine in pyramidal neurons. Our data provide the first indication that retigabine controls neuronal firing properties primarily through KCNQ3 channels.
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Affiliation(s)
- Nissi Varghese
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Anna Lauritano
- Department of Neuroscience, University of Naples Federico II, Naples, Italy
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30
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Activation of KCNQ4 as a Therapeutic Strategy to Treat Hearing Loss. Int J Mol Sci 2021; 22:ijms22052510. [PMID: 33801540 PMCID: PMC7958948 DOI: 10.3390/ijms22052510] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/16/2021] [Accepted: 02/22/2021] [Indexed: 12/14/2022] Open
Abstract
Potassium voltage-gated channel subfamily q member 4 (KCNQ4) is a voltage-gated potassium channel that plays essential roles in maintaining ion homeostasis and regulating hair cell membrane potential. Reduction of the activity of the KCNQ4 channel owing to genetic mutations is responsible for nonsyndromic hearing loss, a typically late-onset, initially high-frequency loss progressing over time. In addition, variants of KCNQ4 have also been associated with noise-induced hearing loss and age-related hearing loss. Therefore, the discovery of small compounds activating or potentiating KCNQ4 is an important strategy for the curative treatment of hearing loss. In this review, we updated the current concept of the physiological role of KCNQ4 in the inner ear and the pathologic mechanism underlying the role of KCNQ4 variants with regard to hearing loss. Finally, we focused on currently developed KCNQ4 activators and their pros and cons, paving the way for the future development of specific KCNQ4 activators as a remedy for hearing loss.
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31
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Li X, Zhang Q, Guo P, Fu J, Mei L, Lv D, Wang J, Lai D, Ye S, Yang H, Guo J. Molecular basis for ligand activation of the human KCNQ2 channel. Cell Res 2021; 31:52-61. [PMID: 32884139 PMCID: PMC7852908 DOI: 10.1038/s41422-020-00410-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 08/14/2020] [Indexed: 01/10/2023] Open
Abstract
The voltage-gated potassium channel KCNQ2 is responsible for M-current in neurons and is an important drug target to treat epilepsy, pain and several other diseases related to neuronal hyper-excitability. A list of synthetic compounds have been developed to directly activate KCNQ2, yet our knowledge of their activation mechanism is limited, due to lack of high-resolution structures. Here, we report cryo-electron microscopy (cryo-EM) structures of the human KCNQ2 determined in apo state and in complex with two activators, ztz240 or retigabine, which activate KCNQ2 through different mechanisms. The activator-bound structures, along with electrophysiology analysis, reveal that ztz240 binds at the voltage-sensing domain and directly stabilizes it at the activated state, whereas retigabine binds at the pore domain and activates the channel by an allosteric modulation. By accurately defining ligand-binding sites, these KCNQ2 structures not only reveal different ligand recognition and activation mechanisms, but also provide a structural basis for drug optimization and design.
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Affiliation(s)
- Xiaoxiao Li
- Department of Biophysics, and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310058, China
| | - Qiansen Zhang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Peipei Guo
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Jie Fu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China
| | - Lianghe Mei
- Suzhou Institute of Drug Innovation, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 108 Yuxin Road, Suzhou, Jiangsu, 215123, China
| | - Dashuai Lv
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Jiangqin Wang
- Department of Biophysics, and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310058, China
| | - Dongwu Lai
- Department of Cardiology, Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310016, China
| | - Sheng Ye
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310058, China
- School of Life Sciences, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, 300072, China
| | - Huaiyu Yang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, 500 Dongchuan Road, Shanghai, 200241, China.
| | - Jiangtao Guo
- Department of Biophysics, and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310058, China.
- Department of Cardiology, Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310016, China.
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Liu Y, Bian X, Wang K. Pharmacological Activation of Neuronal Voltage-Gated Kv7/KCNQ/M-Channels for Potential Therapy of Epilepsy and Pain. Handb Exp Pharmacol 2021; 267:231-251. [PMID: 33837465 DOI: 10.1007/164_2021_458] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Native M-current is a low-threshold, slowly activating potassium current that exerts an inhibitory control over neuronal excitability. The M-channel is primarily co-assembled by heterotetrameric Kv7.2/KCNQ2 and Kv7.3/KCNQ3 subunits that are specifically expressed in the brain and peripheral nociceptive and visceral sensory neurons in the spinal cord. Reduction of M-channel function leads to neuronal hyperexcitability that defines the fundamental mechanism of neurological disorders such as epilepsy and pain, indicating that pharmacological activation of Kv7/KCNQ/M-channels may serve the basis for the therapy. The well-known KCNQ opener retigabine (ezogabine or Potiga) was approved by FDA in 2011 as an anticonvulsant used for an adjunctive treatment of partial epilepsies. Unfortunately, retigabine was discontinued in 2017 due to its side effects of blue-colored appearance of the skin and eyes after prolonged intake. In addition, flupirtine, a structural derivative of retigabine and a centrally acting non-opioid analgesic, was also withdrawn in 2018 for liver toxicity. Fortunately, these side effects are compound-structures related and can be avoided. Thus, further identification and development of novel potent and selective Kv7 channel openers may lead to an effective therapy with improved safety window for anti-epilepsy and anti-nociception.
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Affiliation(s)
- Yani Liu
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - Xiling Bian
- Department of Pharmacology, Peking University School of Pharmaceutical Sciences, Beijing, China
| | - KeWei Wang
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China. .,Institute of Innovative Drugs Qingdao University, Qingdao, China.
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33
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Abstract
Kv7.1-Kv7.5 (KCNQ1-5) K+ channels are voltage-gated K+ channels with major roles in neurons, muscle cells and epithelia where they underlie physiologically important K+ currents, such as neuronal M current and cardiac IKs. Specific biophysical properties of Kv7 channels make them particularly well placed to control the activity of excitable cells. Indeed, these channels often work as 'excitability breaks' and are targeted by various hormones and modulators to regulate cellular activity outputs. Genetic deficiencies in all five KCNQ genes result in human excitability disorders, including epilepsy, arrhythmias, deafness and some others. Not surprisingly, this channel family attracts considerable attention as potential drug targets. Here we will review biophysical properties and tissue expression profile of Kv7 channels, discuss recent advances in the understanding of their structure as well as their role in various neurological, cardiovascular and other diseases and pathologies. We will also consider a scope for therapeutic targeting of Kv7 channels for treatment of the above health conditions.
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34
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Age-related hearing loss pertaining to potassium ion channels in the cochlea and auditory pathway. Pflugers Arch 2020; 473:823-840. [PMID: 33336302 PMCID: PMC8076138 DOI: 10.1007/s00424-020-02496-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/27/2020] [Accepted: 11/10/2020] [Indexed: 12/12/2022]
Abstract
Age-related hearing loss (ARHL) is the most prevalent sensory deficit in the elderly and constitutes the third highest risk factor for dementia. Lifetime noise exposure, genetic predispositions for degeneration, and metabolic stress are assumed to be the major causes of ARHL. Both noise-induced and hereditary progressive hearing have been linked to decreased cell surface expression and impaired conductance of the potassium ion channel KV7.4 (KCNQ4) in outer hair cells, inspiring future therapies to maintain or prevent the decline of potassium ion channel surface expression to reduce ARHL. In concert with KV7.4 in outer hair cells, KV7.1 (KCNQ1) in the stria vascularis, calcium-activated potassium channels BK (KCNMA1) and SK2 (KCNN2) in hair cells and efferent fiber synapses, and KV3.1 (KCNC1) in the spiral ganglia and ascending auditory circuits share an upregulated expression or subcellular targeting during final differentiation at hearing onset. They also share a distinctive fragility for noise exposure and age-dependent shortfalls in energy supply required for sustained surface expression. Here, we review and discuss the possible contribution of select potassium ion channels in the cochlea and auditory pathway to ARHL. We postulate genes, proteins, or modulators that contribute to sustained ion currents or proper surface expressions of potassium channels under challenging conditions as key for future therapies of ARHL.
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Baldwin SN, Sandow SL, Mondéjar-Parreño G, Stott JB, Greenwood IA. K V7 Channel Expression and Function Within Rat Mesenteric Endothelial Cells. Front Physiol 2020; 11:598779. [PMID: 33364977 PMCID: PMC7750541 DOI: 10.3389/fphys.2020.598779] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 11/13/2020] [Indexed: 01/04/2023] Open
Abstract
Background and Purpose: Arterial diameter is dictated by the contractile state of the vascular smooth muscle cells (VSMCs), which is modulated by direct and indirect inputs from endothelial cells (ECs). Modulators of KCNQ-encoded kV7 channels have considerable impact on arterial diameter and these channels are known to be expressed in VSMCs but not yet defined in ECs. However, expression of kV7 channels in ECs would add an extra level of vascular control. This study aims to characterize the expression and function of KV7 channels within rat mesenteric artery ECs. Experimental Approach: In rat mesenteric artery, KCNQ transcript and KV7 channel protein expression were determined via RT-qPCR, immunocytochemistry, immunohistochemistry and immunoelectron microscopy. Wire myography was used to determine vascular reactivity. Key Results: KCNQ transcript was identified in isolated ECs and VSMCs. KV7.1, KV7.4 and KV7.5 protein expression was determined in both isolated EC and VSMC and in whole vessels. Removal of ECs attenuated vasorelaxation to two structurally different KV7.2-5 activators S-1 and ML213. KIR2 blockers ML133, and BaCl2 also attenuated S-1 or ML213-mediated vasorelaxation in an endothelium-dependent process. KV7 inhibition attenuated receptor-dependent nitric oxide (NO)-mediated vasorelaxation to carbachol, but had no impact on relaxation to the NO donor, SNP. Conclusion and Implications: In rat mesenteric artery ECs, KV7.4 and KV7.5 channels are expressed, functionally interact with endothelial KIR2.x channels and contribute to endogenous eNOS-mediated relaxation. This study identifies KV7 channels as novel functional channels within rat mesenteric ECs and suggests that these channels are involved in NO release from the endothelium of these vessels.
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Affiliation(s)
- Samuel N Baldwin
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, London, United Kingdom
| | - Shaun L Sandow
- Biomedical Science, School of Health and Sports Science, University of the Sunshine Coast, Maroochydore, QLD, Australia
| | - Gema Mondéjar-Parreño
- Department of Pharmacology and Toxicology, School of Medicine, Complutense University of Madrid, Madrid, Spain
| | - Jennifer B Stott
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, London, United Kingdom
| | - Iain A Greenwood
- Vascular Biology Research Centre, Institute of Molecular and Clinical Sciences, St George's University of London, London, United Kingdom
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Li T, Wu K, Yue Z, Wang Y, Zhang F, Shen H. Structural Basis for the Modulation of Human KCNQ4 by Small-Molecule Drugs. Mol Cell 2020; 81:25-37.e4. [PMID: 33238160 DOI: 10.1016/j.molcel.2020.10.037] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/28/2020] [Accepted: 10/28/2020] [Indexed: 12/17/2022]
Abstract
Among the five KCNQ channels, also known as the Kv7 voltage-gated potassium (Kv) channels, KCNQ2-KCNQ5 control neuronal excitability. Dysfunctions of KCNQ2-KCNQ5 are associated with neurological disorders such as epilepsy, deafness, and neuropathic pain. Here, we report the cryoelectron microscopy (cryo-EM) structures of human KCNQ4 and its complexes with the opener retigabine or the blocker linopirdine at overall resolutions of 2.5, 3.1, and 3.3 Å, respectively. In all structures, a phosphatidylinositol 4,5-bisphosphate (PIP2) molecule inserts its head group into a cavity within each voltage-sensing domain (VSD), revealing an unobserved binding mode for PIP2. Retigabine nestles in each fenestration, inducing local shifts. Instead of staying within the central pore, linopirdine resides in a cytosolic cavity underneath the inner gate. Electrophysiological analyses of various mutants corroborated the structural observations. Our studies reveal the molecular basis for the modulatory mechanism of neuronal KCNQ channels and provide a framework for structure-facilitated drug discovery targeting these important channels.
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Affiliation(s)
- Tian Li
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Kun Wu
- Emergency Medicine Clinical Research Center, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Medical Research Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, China
| | - Zhenlei Yue
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Yifei Wang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Fan Zhang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China
| | - Huaizong Shen
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China; Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310024, China.
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Kurata HT. Chemical regulation of Kv7 channels: Diverse scaffolds, sites, and mechanisms of action. J Gen Physiol 2020; 152:151830. [PMID: 32484852 PMCID: PMC7398145 DOI: 10.1085/jgp.202012598] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Kv7 channels are powerfully regulated by a wide variety of physiological and pharmacological signals. Larsson et al. describe the direct modulation of Kv7 channels by endocannabinoids and explore how combinations of Kv7 activators with distinct subtype specificities might lead to effective and selective drug cocktails.
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Affiliation(s)
- Harley T Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
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38
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Impact of predictive, preventive and precision medicine strategies in epilepsy. Nat Rev Neurol 2020; 16:674-688. [PMID: 33077944 DOI: 10.1038/s41582-020-0409-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/01/2020] [Indexed: 12/15/2022]
Abstract
Over the last decade, advances in genetics, neuroimaging and EEG have enabled the aetiology of epilepsy to be identified earlier in the disease course than ever before. At the same time, progress in the study of experimental models of epilepsy has provided a better understanding of the mechanisms underlying the condition and has enabled the identification of therapies that target specific aetiologies. We are now witnessing the impact of these advances in our daily clinical practice. Thus, now is the time for a paradigm shift in epilepsy treatment from a reactive attitude, treating patients after the onset of epilepsy and the initiation of seizures, to a proactive attitude that is more broadly integrated into a 'P4 medicine' approach. This P4 approach, which is personalized, predictive, preventive and participatory, puts patients at the centre of their own care and, ultimately, aims to prevent the onset of epilepsy. This aim will be achieved by adapting epilepsy treatments not only to a given syndrome but also to a given patient and moving from the usual anti-seizure treatments to personalized treatments designed to target specific aetiologies. In this Review, we present the current state of this ongoing revolution, emphasizing the impact on clinical practice.
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39
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Malysz J, Petkov GV. Detrusor Smooth Muscle K V7 Channels: Emerging New Regulators of Urinary Bladder Function. Front Physiol 2020; 11:1004. [PMID: 33041840 PMCID: PMC7526500 DOI: 10.3389/fphys.2020.01004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/23/2020] [Indexed: 01/21/2023] Open
Abstract
Relaxation and contraction of the urinary bladder smooth muscle, also known as the detrusor smooth muscle (DSM), facilitate the micturition cycle. DSM contractility depends on cell excitability, which is established by the synchronized activity of multiple diverse ion channels. K+ channels, the largest family of channels, control DSM excitability by maintaining the resting membrane potential and shaping the action potentials that cause the phasic contractions. Among the members of the voltage-gated K+ (KV) channel superfamily, KV type 7 (KV7) channels - KV7.1-KV7.5 members encoded by KCNQ1-KCNQ5 genes - have been recently identified as functional regulators in various cell types including vascular, cardiac, and neuronal cells. Their regulatory roles in DSM, however, are just now emerging and remain to be elucidated. To address this gap, our research group has initiated the systematic investigation of human DSM KV7 channels in collaboration with clinical urologists. In this comprehensive review, we summarize the current understanding of DSM Kv7 channels and highlight recent discoveries in the field. We describe KV7 channel expression profiles at the mRNA and protein levels, and further elaborate on functional effects of KV7 channel selective modulators on DSM excitability, contractility, and intracellular Ca2+ dynamics in animal species along with in vivo studies and the limited data on human DSM. Within each topic, we highlight the main observations, current gaps in knowledge, and most pressing questions and concepts in need of resolution. We emphasize the lack of systematic studies on human DSM KV7 channels that are now actively ongoing in our laboratory.
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Affiliation(s)
- John Malysz
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Georgi V. Petkov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, United States
- Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Department of Urology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
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40
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Grupe M, Bentzen BH, Benned-Jensen T, Nielsen V, Frederiksen K, Jensen HS, Jacobsen AM, Skibsbye L, Sams AG, Grunnet M, Rottländer M, Bastlund JF. In vitro and in vivo characterization of Lu AA41178: A novel, brain penetrant, pan-selective Kv7 potassium channel opener with efficacy in preclinical models of epileptic seizures and psychiatric disorders. Eur J Pharmacol 2020; 887:173440. [PMID: 32745603 DOI: 10.1016/j.ejphar.2020.173440] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/29/2022]
Abstract
Activation of the voltage-gated Kv7 channels holds therapeutic promise in several neurological and psychiatric disorders, including epilepsy, schizophrenia, and depression. Here, we present a pharmacological characterization of Lu AA41178, a novel, pan-selective Kv7.2-7.5 opener, using both in vitro assays and a broad range of in vivo assays with relevance to epilepsy, schizophrenia, and depression. Electrophysiological characterization in Xenopus oocytes expressing human Kv7.2-Kv7.5 confirmed Lu AA41178 as a pan-selective opener of Kv7 channels by significantly left-shifting the activation threshold. Additionally, Lu AA41178 was tested in vitro for off-target effects, demonstrating a clean Kv7-selective profile, with no impact on common cardiac ion channels, and no potentiating activity on GABAA channels. Lu AA41178 was evaluated across preclinical in vivo assays with relevance to neurological and psychiatric disorders. In the maximum electroshock seizure threshold test and PTZ seizure threshold test, Lu AA41178 significantly increased the seizure thresholds in mice, demonstrating anticonvulsant efficacy. Lu AA41178 demonstrated antipsychotic-like activity by reducing amphetamine-induced hyperlocomotion in mice as well as lowering conditioned avoidance responses in rats. In the mouse forced swim test, a model with antidepressant predictivity, Lu AA41178 significantly reduced immobility. Additionally, behavioral effects typically observed with Kv7 openers was also characterized. In vivo assays were accompanied by plasma and brain exposures, revealing minimum effective plasma levels <1000 ng/ml. Lu AA41178, a potent opener of neuronal Kv7 channels demonstrate efficacy in assays of epilepsy, schizophrenia and depression and might serve as a valuable tool for exploring the role of Kv7 channels in both neurological and psychiatric disorders.
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Affiliation(s)
- Morten Grupe
- H. Lundbeck A/S, Ottiliavej 9, 2500 Valby, Denmark.
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark
| | | | | | | | | | | | | | | | | | - Mario Rottländer
- CMC Outsourcing, Novo Nordisk A/S, Smoermosevej 17-19, 2880 Bagsvaerd, Denmark
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41
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Wilenkin B, Burris KD, Eastwood BJ, Sher E, Williams AC, Priest BT. Development of an Electrophysiological Assay for Kv7 Modulators on IonWorks Barracuda. Assay Drug Dev Technol 2020; 17:310-321. [PMID: 31634018 DOI: 10.1089/adt.2019.942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Relief from chronic pain continues to represent a large unmet need. The voltage-gated potassium channel Kv7.2/7.3, also known as KCNQ2/3, is a key contributor to the control of resting membrane potential and excitability in nociceptive neurons and represents a promising target for potential therapeutics. In this study, we present a medium throughput electrophysiological assay for the identification and characterization of modulators of Kv7.2/7.3 channels, using the IonWorks Barracuda™ automated voltage clamp platform. The assay combines a family of voltage steps used to construct conductance curves with a unique analysis method. Kv7.2/7.3 modulators shift the activation voltage and/or change the maximal conductance of the current, and both parameters have been used to quantify compound mediated effects. Both effects are expected to modulate neuronal excitability in vivo. The analysis method described assigns a single potency value that combines changes in activation voltage and maximal conductance and is expected to predict compound mediated changes in excitability.
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Affiliation(s)
- Benjamin Wilenkin
- Department of Quantitative Biology, Eli Lilly and Company, Indianapolis, Indiana
| | - Kevin D Burris
- Department of Quantitative Biology, Eli Lilly and Company, Indianapolis, Indiana
| | - Brian J Eastwood
- Department of Statistics, Eli Lilly and Company, Indianapolis, Indiana
| | - Emanuele Sher
- Department of Discovery Pain Group, Eli Lilly and Company, Indianapolis, Indiana
| | - Andrew C Williams
- Department of Medicinal Chemistry, Eli Lilly and Company, Indianapolis, Indiana
| | - Birgit T Priest
- Department of Quantitative Biology, Eli Lilly and Company, Indianapolis, Indiana
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42
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Abstract
Kv7 channels (Kv7.1-7.5) are voltage-gated K+ channels that can be modulated by five β-subunits (KCNE1-5). Kv7.1-KCNE1 channels produce the slow-delayed rectifying K+ current, IKs, which is important during the repolarization phase of the cardiac action potential. Kv7.2-7.5 are predominantly neuronally expressed and constitute the muscarinic M-current and control the resting membrane potential in neurons. Kv7.1 produces drastically different currents as a result of modulation by KCNE subunits. This flexibility allows the Kv7.1 channel to have many roles depending on location and assembly partners. The pharmacological sensitivity of Kv7.1 channels differs from that of Kv7.2-7.5 and is largely dependent upon the number of β-subunits present in the channel complex. As a result, the development of pharmaceuticals targeting Kv7.1 is problematic. This review discusses the roles and the mechanisms by which different signaling pathways affect Kv7.1 and KCNE channels and could potentially provide different ways of targeting the channel.
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Affiliation(s)
- Emely Thompson
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
| | - David Fedida
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada;
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43
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Redford KE, Abbott GW. The ubiquitous flavonoid quercetin is an atypical KCNQ potassium channel activator. Commun Biol 2020; 3:356. [PMID: 32641720 PMCID: PMC7343821 DOI: 10.1038/s42003-020-1089-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/18/2020] [Indexed: 12/11/2022] Open
Abstract
Many commonly consumed plants are used as folk medicines, often with unclear molecular mechanisms. Recent studies uncovered the ubiquitous and influential KCNQ family of voltage-gated potassium (Kv) channels as a therapeutic target for several medicinal plant compounds. Capers - immature flower buds of Capparis spinosa - have been consumed for food and medicinal purposes for millennia. Here, we show that caper extract hyperpolarizes cells expressing KCNQ1 or KCNQ2/3 Kv channels. Capers are the richest known natural source of quercetin, the most consumed dietary flavonoid. Quercetin potentiated KCNQ1/KCNE1, KCNQ2/3 and KCNQ4 currents but, unusually, not KCNQ5. Strikingly, quercetin augmented both activation and inactivation of KCNQ1, via a unique KCNQ activation mechanism involving sites atop the voltage sensor and in the pore. The findings uncover a novel potential molecular basis for therapeutic effects of quercetin-rich foods and a new chemical space for atypical modes of KCNQ channel modulation. Kaitlyn E. Redford and Geoffrey W. Abbott show that quercetin, a flavonoid highly expressed in capers, potentiates KCNQ currents to varying degrees depending on the subunit composition of the channel complex. By combining in silico docking, mutagenesis, and electrophysiology they show that this flavonoid can bind KCNQ channels atop the voltage sensor and within the pore module, highlighting an atypical mode of channel modulation.
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Affiliation(s)
- Kaitlyn E Redford
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA.
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44
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Mondejar-Parreño G, Perez-Vizcaino F, Cogolludo A. Kv7 Channels in Lung Diseases. Front Physiol 2020; 11:634. [PMID: 32676036 PMCID: PMC7333540 DOI: 10.3389/fphys.2020.00634] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/18/2020] [Indexed: 12/23/2022] Open
Abstract
Lung diseases constitute a global health concern causing disability. According to WHO in 2016, respiratory diseases accounted for 24% of world population mortality, the second cause of death after cardiovascular diseases. The Kv7 channels family is a group of voltage-dependent K+ channels (Kv) encoded by KCNQ genes that are involved in various physiological functions in numerous cell types, especially, cardiac myocytes, smooth muscle cells, neurons, and epithelial cells. Kv7 channel α-subunits are regulated by KCNE1–5 ancillary β-subunits, which modulate several characteristics of Kv7 channels such as biophysical properties, cell-location, channel trafficking, and pharmacological sensitivity. Kv7 channels are mainly expressed in two large groups of lung tissues: pulmonary arteries (PAs) and bronchial tubes. In PA, Kv7 channels are expressed in pulmonary artery smooth muscle cells (PASMCs); while in the airway (trachea, bronchus, and bronchioles), Kv7 channels are expressed in airway smooth muscle cells (ASMCs), airway epithelial cells (AEPs), and vagal airway C-fibers (VACFs). The functional role of Kv7 channels may vary depending on the cell type. Several studies have demonstrated that the impairment of Kv7 channel has a strong impact on pulmonary physiology contributing to the pathophysiology of different respiratory diseases such as cystic fibrosis, asthma, chronic obstructive pulmonary disease, chronic coughing, lung cancer, and pulmonary hypertension. Kv7 channels are now recognized as playing relevant physiological roles in many tissues, which have encouraged the search for Kv7 channel modulators with potential therapeutic use in many diseases including those affecting the lung. Modulation of Kv7 channels has been proposed to provide beneficial effects in a number of lung conditions. Therefore, Kv7 channel openers/enhancers or drugs acting partly through these channels have been proposed as bronchodilators, expectorants, antitussives, chemotherapeutics and pulmonary vasodilators.
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Affiliation(s)
- Gema Mondejar-Parreño
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain.,Ciber Enfermedades Respiratorias (Ciberes), Madrid, Spain.,Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Madrid, Spain
| | - Francisco Perez-Vizcaino
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain.,Ciber Enfermedades Respiratorias (Ciberes), Madrid, Spain.,Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Madrid, Spain
| | - Angel Cogolludo
- Departamento de Farmacología y Toxicología, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain.,Ciber Enfermedades Respiratorias (Ciberes), Madrid, Spain.,Instituto de Investigación Sanitaria Gregorio Marañón (IISGM), Madrid, Spain
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Abbott GW. KCNQs: Ligand- and Voltage-Gated Potassium Channels. Front Physiol 2020; 11:583. [PMID: 32655402 PMCID: PMC7324551 DOI: 10.3389/fphys.2020.00583] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/11/2020] [Indexed: 12/26/2022] Open
Abstract
Voltage-gated potassium (Kv) channels in the KCNQ (Kv7) family are essential features of a broad range of excitable and non-excitable cell types and are found in organisms ranging from Hydra vulgaris to Homo sapiens. Although they are firmly in the superfamily of S4 domain-bearing voltage-sensing ion channels, KCNQ channels are highly sensitive to a range of endogenous and exogenous small molecules that act directly on the pore, the voltage-sensing domain, or the interface between the two. The focus of this review is regulation of KCNQs by direct binding of neurotransmitters and metabolites from both animals and plants and the role of the latter in the effects of plants consumed for food and as traditional folk medicines. The conceptual question arises: Are KCNQs voltage-gated channels that are also sensitive to ligands or ligand-gated channels that are also sensitive to voltage?
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
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Villalba-Galea CA. Modulation of K V7 Channel Deactivation by PI(4,5)P 2. Front Pharmacol 2020; 11:895. [PMID: 32636742 PMCID: PMC7318307 DOI: 10.3389/fphar.2020.00895] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 06/02/2020] [Indexed: 01/16/2023] Open
Abstract
The activity of KV7 channels critically contributes to the regulation of cellular electrical excitability in many cell types. In the central nervous system, the heteromeric KV7.2/KV7.3 channel is thought to be the chief molecular entity giving rise to M-currents. These K+-currents as so called because they are inhibited by the activation of Gq protein-coupled muscarinic receptors. In general, activation of Gq protein-coupled receptors (GqPCRs) decreases the concentration of the phosphoinositide PI(4,5)P2 which is required for KV7 channel activity. It has been recently reported that the deactivation rate of KV7.2/KV7.3 channels decreases as a function of activation. This suggests that the activated/open channel stabilizes as activation persists. This property has been regarded as evidence for the existence of modal behavior in the activity of these channels. In particular, it has been proposed that the heteromeric KV7.2/KV7.3 channel has at least two modes of activity that can be distinguished by both their deactivation kinetics and sensitivity to Retigabine. The current study was aimed at understanding the effect of PI(4,5)P2 depletion on the modal behavior of KV7.2/KV7.3 channels. Here, it was hypothesized that depleting the membrane of P(4,5)P2 would hamper the stabilization of the activated/open channel, resulting in higher rates of deactivation of the heteromeric KV7.2/KV7.3 channel. In addressing this question, it was found that the activity-dependent slowdown of the deactivation was not as prominent when channels were co-expressed with the chimeric phosphoinositide-phosphatase Ci-VS-TPIP or when cells were treated with the phosphoinositide kinase inhibitor Wortmannin. Further, it was observed that either of these approaches to deplete PI(4,5)P2 had a higher impact on the kinetic of deactivation following prolonged activation, while having little or no effect when activation was short-lived. Furthermore, it was observed that the action of either Ci-VS-TPIP or Wortmannin reduced the effect of Retigabine on the kinetics of deactivation, having a higher impact when activation was prolonged. These combined observations led to the conclusion that the deactivation kinetic of KV7.2/KV7.3 channels was sensitive to PI(4,5)P2 depletion in an activation-dependent manner, displaying a stronger effect on deactivation following prolonged activation.
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Affiliation(s)
- Carlos A. Villalba-Galea
- Department of Physiology and Pharmacology, Thomas J. Long School of Pharmacy, University of the Pacific, Stockton, CA, United States
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Van Theemsche KM, Van de Sande DV, Snyders DJ, Labro AJ. Hydrophobic Drug/Toxin Binding Sites in Voltage-Dependent K + and Na + Channels. Front Pharmacol 2020; 11:735. [PMID: 32499709 PMCID: PMC7243439 DOI: 10.3389/fphar.2020.00735] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 05/04/2020] [Indexed: 12/26/2022] Open
Abstract
In the Nav channel family the lipophilic drugs/toxins binding sites and the presence of fenestrations in the channel pore wall are well defined and categorized. No such classification exists in the much larger Kv channel family, although certain lipophilic compounds seem to deviate from binding to well-known hydrophilic binding sites. By mapping different compound binding sites onto 3D structures of Kv channels, there appear to be three distinct lipid-exposed binding sites preserved in Kv channels: the front and back side of the pore domain, and S2-S3/S3-S4 clefts. One or a combination of these sites is most likely the orthologous equivalent of neurotoxin site 5 in Nav channels. This review describes the different lipophilic binding sites and location of pore wall fenestrations within the Kv channel family and compares it to the knowledge of Nav channels.
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Affiliation(s)
- Kenny M Van Theemsche
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
| | - Dieter V Van de Sande
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
| | - Dirk J Snyders
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
| | - Alain J Labro
- Laboratory of Molecular, Cellular, and Network Excitability, University of Antwerp, Antwerp, Belgium
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Shi S, Li J, Sun F, Chen Y, Pang C, Geng Y, Qi J, Guo S, Wang X, Zhang H, Zhan Y, An H. Molecular Mechanisms and Structural Basis of Retigabine Analogues in Regulating KCNQ2 Channel. J Membr Biol 2020; 253:167-181. [DOI: 10.1007/s00232-020-00113-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/05/2020] [Indexed: 12/22/2022]
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Sills GJ, Rogawski MA. Mechanisms of action of currently used antiseizure drugs. Neuropharmacology 2020; 168:107966. [PMID: 32120063 DOI: 10.1016/j.neuropharm.2020.107966] [Citation(s) in RCA: 230] [Impact Index Per Article: 57.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 01/09/2020] [Accepted: 01/12/2020] [Indexed: 02/08/2023]
Abstract
Antiseizure drugs (ASDs) prevent the occurrence of seizures; there is no evidence that they have disease-modifying properties. In the more than 160 years that orally administered ASDs have been available for epilepsy therapy, most agents entering clinical practice were either discovered serendipitously or with the use of animal seizure models. The ASDs originating from these approaches act on brain excitability mechanisms to interfere with the generation and spread of epileptic hyperexcitability, but they do not address the specific defects that are pathogenic in the epilepsies for which they are prescribed, which in most cases are not well understood. There are four broad classes of such ASD mechanisms: (1) modulation of voltage-gated sodium channels (e.g. phenytoin, carbamazepine, lamotrigine), voltage-gated calcium channels (e.g. ethosuximide), and voltage-gated potassium channels [e.g. retigabine (ezogabine)]; (2) enhancement of GABA-mediated inhibitory neurotransmission (e.g. benzodiazepines, tiagabine, vigabatrin); (3) attenuation of glutamate-mediated excitatory neurotransmission (e.g. perampanel); and (4) modulation of neurotransmitter release via a presynaptic action (e.g. levetiracetam, brivaracetam, gabapentin, pregabalin). In the past two decades there has been great progress in identifying the pathophysiological mechanisms of many genetic epilepsies. Given this new understanding, attempts are being made to engineer specific small molecule, antisense and gene therapies that functionally reverse or structurally correct pathogenic defects in epilepsy syndromes. In the near future, these new therapies will begin a paradigm shift in the treatment of some rare genetic epilepsy syndromes, but targeted therapies will remain elusive for the vast majority of epilepsies until their causes are identified. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.
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Affiliation(s)
- Graeme J Sills
- School of Life Sciences, University of Glasgow, Glasgow, UK.
| | - Michael A Rogawski
- Department of Neurology, School of Medicine, University of California, Davis, Sacramento, CA, USA; Department of Pharmacology, School of Medicine, University of California, Davis, Sacramento, CA, USA
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Mir A, Qahtani M, Bashir S. GRIN2A -Related Severe Epileptic Encephalopathy Treated with Memantine: An Example of Precision Medicine. J Pediatr Genet 2019; 9:252-257. [PMID: 32765929 DOI: 10.1055/s-0039-3401028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 11/04/2019] [Indexed: 01/07/2023]
Abstract
Epileptic spasm (ES) is one of the seizure types which is difficult to treat. Next-generation sequencing has facilitated rapid gene discovery that is linked to ES and GRIN2A being one of them. Genotype-driven precision medicine is on the horizon and is a targeted treatment approach toward the precise molecular cause of the disease. GRIN2A gene encodes for a subunit of N-methyl-D-aspartate (NMDA) receptor and it has been suggested from in vitro studies and few case reports that memantine, a NMDA receptor antagonist, was shown to reduce seizures in patients with GRIN2A mutations. Here, we describe a patient with a novel GRIN2A mutation and severe drug-resistant ES who became seizure free with memantine.
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Affiliation(s)
- Ali Mir
- Department of Pediatric Neurology, Neuroscience Center, King Fahad Specialist Hospital, Dammam, Saudi Arabia
| | - Mohammed Qahtani
- Department of Pediatric Neurology, Neuroscience Center, King Fahad Specialist Hospital, Dammam, Saudi Arabia
| | - Shahid Bashir
- Neuroscience Center, King Fahad Specialist Hospital, Dammam, Saudi Arabia.,Berenson-Allen Center for Non-invasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States
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