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Vitello R, Taouba H, Derand M, Liégeois JF. The Bis(1,2,3,4-tetrahydroisoquinoline) Alkaloids Cepharanthine and Berbamine Are Ligands of SK Channels. ACS Med Chem Lett 2024; 15:215-220. [PMID: 38352826 PMCID: PMC10860169 DOI: 10.1021/acsmedchemlett.3c00452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/22/2023] [Accepted: 12/28/2023] [Indexed: 02/16/2024] Open
Abstract
Cepharanthine, a multitarget alkaloid which has recently been shown to be effective against SARS-Cov-2, and berbamine, an alkaloid characterized as a calcium channel blocker, both share key structural elements with known small conductance calcium-activated potassium (SK) channel blockers. These structural similarities led us to evaluate their affinity for SK channels. Therefore, we performed in vitro binding on SK2 and SK3 subtypes and highlighted micromolar to sub-micromolar affinities. Respectively, the Ki values on SK2 and SK3 are 1,318 μM and 1,091 μM for cepharanthine and 0,284 μM and 0,679 μM for berbamine. These newfound affinities correspond to the concentrations at which the alkaloids are found to be active against several pathologies. As SK interactions occur at the same levels as their therapeutic effects, there is a strong incentive to further investigate whether SK channels are involved in their pharmaceutical potency.
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Affiliation(s)
- Romain Vitello
- University of Liège (ULiège), CIRM, Laboratory of Medicinal Chemistry, Liège (4000), Belgium
| | - Hossein Taouba
- University of Liège (ULiège), CIRM, Laboratory of Medicinal Chemistry, Liège (4000), Belgium
| | - Marine Derand
- University of Liège (ULiège), CIRM, Laboratory of Medicinal Chemistry, Liège (4000), Belgium
| | - Jean-François Liégeois
- University of Liège (ULiège), CIRM, Laboratory of Medicinal Chemistry, Liège (4000), Belgium
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2
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Wang A, Zhou Y, Chen H, Jin J, Mao Y, Tao S, Qiu T. Inhibition of SK Channels in VTA Affects Dopaminergic Neurons to Improve the Depression-Like Behaviors of Post-Stroke Depression Rats. Neuropsychiatr Dis Treat 2023; 19:2127-2139. [PMID: 37840624 PMCID: PMC10572402 DOI: 10.2147/ndt.s426091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 09/22/2023] [Indexed: 10/17/2023] Open
Abstract
Purpose This study aimed to investigate the effect of small-conductance calcium-activated potassium channels (SK channels) on the dopaminergic (DA) neuron pathways in the ventral tegmental area (VTA) during the pathogenesis of post-stroke depression (PSD) and explore the improvement of PSD by inhibiting the SK channels. Patients and Methods Four groups of Sprague-Dawley rats were randomly divided: Control, PSD, SK channel inhibitor (apamin) and SK channel activator (CyPPA) groups. In both control and CyPPA groups, sham surgery was performed. In the other two groups, middle cerebral arteries were occluded. The behavioral indicators related to depression in different groups were compared. Immunofluorescence was used to measure the activity of DA neurons in the VTA, while qRT-PCR was used to assess the expression of SK channel genes. Results The results showed that apamin treatment improved behavioral indicators related to depression compared to the PSD group. Furthermore, the qRT-PCR analysis revealed differential expression of the KCNN1 and KCNN3 subgenes of the SK channels in each group. Immunofluorescence analysis revealed an increase in the expression of DA neurons in the VTA of the PSD group, which was subsequently reduced upon apamin intervention. Conclusion This study suggests that SK channel activation following stroke contributes to depression-related behaviors in PSD rats through increased expression of DA neurons in the VTA. And depression-related behavior is improved in PSD rats by inhibiting the SK channels. The results of this study provide a new understanding of PSD pathogenesis and the possibility of developing new strategies to prevent PSD by targeting SK channels.
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Affiliation(s)
- Anqi Wang
- First Clinical Medical College, Zhejiang Chinese Medical University, Zhejiang, People’s Republic of China
| | - Yujia Zhou
- Second Clinical Medical College, Zhejiang Chinese Medical University, Zhejiang, People’s Republic of China
| | - Huangying Chen
- First Clinical Medical College, Zhejiang Chinese Medical University, Zhejiang, People’s Republic of China
| | - Jiawei Jin
- First Clinical Medical College, Zhejiang Chinese Medical University, Zhejiang, People’s Republic of China
| | - Yingqi Mao
- Faculty of Chinese Medicine, Macau University of Science and Technology, Macau, People’s Republic of China
| | - Shuiliang Tao
- Basic Medicine College, Zhejiang Chinese Medical University, Zhejiang, People’s Republic of China
| | - Tao Qiu
- Department of Neurology, The First Affiliated Hospital of Zhejiang Chinese Medical University, Zhejiang, People’s Republic of China
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Kouba S, Braire J, Félix R, Chantôme A, Jaffrès PA, Lebreton J, Dubreuil D, Pipelier M, Zhang X, Trebak M, Vandier C, Mathé-Allainmat M, Potier-Cartereau M. Lipidic synthetic alkaloids as SK3 channel modulators. Synthesis and biological evaluation of 2-substituted tetrahydropyridine derivatives with potential anti-metastatic activity. Eur J Med Chem 2020; 186:111854. [PMID: 31753515 DOI: 10.1016/j.ejmech.2019.111854] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 11/04/2019] [Indexed: 11/18/2022]
Abstract
Small Conductance Calcium (Ca2+)-activated potassium (K+) channels (SKCa) are now proved to be involved in many cancer cell behaviors such as proliferation or migration. The SK3 channel isoform was particularly described in breast cancer where it can be associated with the Orai1 Ca2+ channel to form a complex that regulates the Ca2+ homeostasis during tumor development and acts as a potent mediator of bone metastases development in vivo. Until now, very few specific blockers of Orai1 and/or SK3 have been developed as potential anti-metastatic compounds. In this study, we illustrated the synthesis of new families of lipophilic pyridine and tetrahydropyridine derivatives designed as potential modulators of SK3 channel. The toxicity of the newly synthesized compounds and their migration effects were evaluated on the breast cancer cell line MDA-MB-435s. Two molecules (7a and 10c) demonstrated a significant decrease in the SK3 channel-dependent migration as well as the SK3/Orai1-related Ca2+ entry. Current measurements showed that these compounds are more likely SK3-selective. Taken all together these results suggest that such molecules could be considered as promising anti-metastatic drugs in breast cancer.
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Affiliation(s)
- Sana Kouba
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Julien Braire
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Romain Félix
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Aurélie Chantôme
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Paul-Alain Jaffrès
- University of Brest, CNRS, CEMCA, UMR 6521, 6 Avenue Victor Le Gorgeu, 29238, Brest, France
| | - Jacques Lebreton
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Didier Dubreuil
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Muriel Pipelier
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France
| | - Xuexin Zhang
- Pennylvania State University College of Medicine, Department of Cellular and Molecular Physiology, 700 HMC Crescent Road, Hershey, PA, 17033, USA
| | - Mohamed Trebak
- Pennylvania State University College of Medicine, Department of Cellular and Molecular Physiology, 700 HMC Crescent Road, Hershey, PA, 17033, USA
| | - Christophe Vandier
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France
| | - Monique Mathé-Allainmat
- University of Nantes, CNRS, Faculty of Sciences, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, 2, Rue de La Houssinière, 44322, Nantes Cedex 3, France.
| | - Marie Potier-Cartereau
- University of Tours, Inserm U1069 Nutrition, Croissance et Cancer (N2C), Faculty of Medicine, 10 Boulevard Tonnellé, 37032, Tours Cedex, France.
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Dilly S, Badarau E, Dufour F, Nistor I, Hubert P, Seutin V, Wouters J, Liégeois JF. Structural analysis of some bis-(8-isopropyl-isoquinolinium) derivatives reveals a preferential folded conformation leading to a stereoselective attack by sodium borohydride. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.06.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Liégeois JF, Wouters J, Seutin V, Dilly S. Bis-(1,2,3,4-tetrahydroisoquinolinium): A Chiral Scaffold for Developing High-Affinity Ligands for SK Channels. ChemMedChem 2014; 9:737-40. [DOI: 10.1002/cmdc.201400028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Yang D, Arifhodzic L, Ganellin CR, Jenkinson DH. Further studies on bis-charged tetraazacyclophanes as potent inhibitors of small conductance Ca(2+)-activated K+ channels. Eur J Med Chem 2013; 63:907-23. [PMID: 23685886 DOI: 10.1016/j.ejmech.2013.02.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 02/21/2013] [Accepted: 02/22/2013] [Indexed: 11/20/2022]
Abstract
Previously, quinolinium-based tetraazacyclophanes, such as UCL 1684 and UCL 1848, have been shown to be extraordinarily sensitive to changes in chemical structure (especially to the size of the cyclophane system) with respect to activity as potent non-peptidic blockers of the small conductance Ca(2+)-activated K(+) ion channels (SKCa). The present work has sought to optimize the structure of the linking chains in UCL 1848. We report the synthesis and SKCa channel-blocking activity of 29 analogues of UCL 1848 in which the central CH2 of UCL 1848 is replaced by other groups X or Y = O, S, CF2, CO, CHOH, CC, CHCH, CHMe to explore whether subtle changes in bond length or flexibility can improve potency still further. The possibility of improving potency by introducing ring substituents has also been explored by synthesizing and testing 25 analogues of UCL 1684 and UCL 1848 with substituents (NO2, NH2, CF3, F, Cl, CH3, OCH3, OCF3, OH) in the 5, 6 or 7 positions of the aminoquinolinium rings. As in our earlier work, each compound was assayed for inhibition of the afterhyperpolarization (AHP) in rat sympathetic neurons, an action mediated by the SK3 subtype of the SKCa channel. One of the new compounds (39, R(7) = Cl, UCL 2053) is twice as potent as UCL 1848 and UCL 1684: seven are comparable in activity.
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Affiliation(s)
- Donglai Yang
- Department of Chemistry, University College London, Gower Street, London WC1E 6BT, UK
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7
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The interactions of apamin and tetraethylammonium are differentially affected by single mutations in the pore mouth of small conductance calcium-activated potassium (SK) channels. Biochem Pharmacol 2013; 85:560-9. [DOI: 10.1016/j.bcp.2012.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
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8
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Dilly S, Poncin S, Lamy C, Liégeois JF, Seutin V. Physiologie, pharmacologie et modélisation de canaux potassiques. Med Sci (Paris) 2012; 28:395-402. [DOI: 10.1051/medsci/2012284017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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9
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Synthesis and radioligand binding studies of bis-(8-isopropyl-isoquinolinium) derivatives as ligands for apamin-sensitive sites on cloned SK2 and SK3 channels. Bioorg Med Chem Lett 2011; 21:6756-9. [DOI: 10.1016/j.bmcl.2011.09.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 09/08/2011] [Accepted: 09/13/2011] [Indexed: 11/20/2022]
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10
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Ghasemi Z, Hassanpour-Ezatti M, Kamalinejad M, Janahmadi M. Functional involvement of Ca2+ and Ca2+-activated K+ channels in anethol-induced changes in Ca2+ dependent excitability of F1 neurons in Helix aspersa. Fitoterapia 2011; 82:750-6. [DOI: 10.1016/j.fitote.2011.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 03/10/2011] [Accepted: 03/15/2011] [Indexed: 11/16/2022]
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11
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Dilly S, Lamy C, Marrion NV, Liégeois JF, Seutin V. Ion-channel modulators: more diversity than previously thought. Chembiochem 2011; 12:1808-12. [PMID: 21726033 DOI: 10.1002/cbic.201100236] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Indexed: 12/11/2022]
Abstract
Ion-channel function can be modified in various ways. For example, numerous studies have shown that currents through voltage-gated ion channels are affected by pore block or modification of voltage dependence of activation/inactivation. Recent experiments performed on various ion channels show that allosteric modulation is an important mechanism for affecting channel function. For instance, in K(Ca)2 (formerly SK) channels, the prototypic "blocker" apamin prevents conduction by an allosteric mechanism, while TRPV1 channels are prevented from closing by a tarantula toxin, DkTx, through an interaction with residues located away from the selectivity filter. The recent evidence, therefore, suggests that in several ion channels, the region around the outer mouth of the pore is rich in binding sites and could be exploited therapeutically. These discoveries also suggest that the pharmacological vocabulary should be adapted to define these various actions.
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Affiliation(s)
- Sébastien Dilly
- Laboratory of Medicinal Chemistry and CIRM, University of Liège, 1 Avenue de l'Hôpital, 4000 Liège, Belgium.
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12
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Weatherall KL, Goodchild SJ, Jane DE, Marrion NV. Small conductance calcium-activated potassium channels: From structure to function. Prog Neurobiol 2010; 91:242-55. [DOI: 10.1016/j.pneurobio.2010.03.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 03/05/2010] [Accepted: 03/24/2010] [Indexed: 10/19/2022]
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13
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Lamy C, Goodchild SJ, Weatherall KL, Jane DE, Liégeois JF, Seutin V, Marrion NV. Allosteric block of KCa2 channels by apamin. J Biol Chem 2010; 285:27067-27077. [PMID: 20562108 DOI: 10.1074/jbc.m110.110072] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of small conductance calcium-activated potassium (K(Ca)2) channels can regulate neuronal firing and synaptic plasticity. They are characterized by their high sensitivity to the bee venom toxin apamin, but the mechanism of block is not understood. For example, apamin binds to both K(Ca)2.2 and K(Ca)2.3 with the same high affinity (K(D) approximately 5 pM for both subtypes) but requires significantly higher concentrations to block functional current (IC(50) values of approximately 100 pM and approximately 5 nM, respectively). This suggests that steps beyond binding are needed for channel block to occur. We have combined patch clamp and binding experiments on cell lines with molecular modeling and mutagenesis to gain more insight into the mechanism of action of the toxin. An outer pore histidine residue common to both subtypes was found to be critical for both binding and block by the toxin but not for block by tetraethylammonium (TEA) ions. These data indicated that apamin blocks K(Ca)2 channels by binding to a site distinct from that used by TEA, supported by a finding that the onset of block by apamin was not affected by the presence of TEA. Structural modeling of ligand-channel interaction indicated that TEA binds deep within the channel pore, which contrasted with apamin being modeled to interact with the channel outer pore by utilizing the outer pore histidine residue. This multidisciplinary approach suggested that apamin does not behave as a classical pore blocker but blocks using an allosteric mechanism that is consistent with observed differences between binding affinity and potency of block.
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Affiliation(s)
- Cédric Lamy
- Laboratory of Pharmacology and Groupe Interdisciplinaire de Génoprotéomique Appliquée Neurosciences, University of Liège, 4000 Liège, Belgium
| | - Samuel J Goodchild
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Kate L Weatherall
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - David E Jane
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Jean-François Liégeois
- Laboratory of Medicinal Chemistry and Centre Interfacultaire de Recherche du Medicament, University of Liège, 4000 Liège, Belgium
| | - Vincent Seutin
- Laboratory of Pharmacology and Groupe Interdisciplinaire de Génoprotéomique Appliquée Neurosciences, University of Liège, 4000 Liège, Belgium
| | - Neil V Marrion
- Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, United Kingdom.
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Goodchild SJ, Lamy C, Seutin V, Marrion NV. Inhibition of K(Ca)2.2 and K(Ca)2.3 channel currents by protonation of outer pore histidine residues. ACTA ACUST UNITED AC 2010; 134:295-308. [PMID: 19786583 PMCID: PMC2757770 DOI: 10.1085/jgp.200910252] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Ion channels are often modulated by changes in extracellular pH, with most examples resulting from shifts in the ionization state of histidine residue(s) in the channel pore. The application of acidic extracellular solution inhibited expressed K(Ca)2.2 (SK2) and K(Ca)2.3 (SK3) channel currents, with K(Ca)2.3 (pIC(50) of approximately 6.8) being approximately fourfold more sensitive than K(Ca)2.2 (pIC(50) of approximately 6.2). Inhibition was found to be voltage dependent, resulting from a shift in the affinity for the rectifying intracellular divalent cation(s) at the inner mouth of the selectivity filter. The inhibition by extracellular protons resulted from a reduction in the single-channel conductance, without significant changes in open-state kinetics or open probability. K(Ca)2.2 and K(Ca)2.3 subunits both possess a histidine residue in their outer pore region between the transmembrane S5 segment and the pore helix, with K(Ca)2.3 also exhibiting an additional histidine residue between the selectivity filter and S6. Mutagenesis revealed that the outer pore histidine common to both channels was critical for inhibition. The greater sensitivity of K(Ca)2.3 currents to protons arose from the additional histidine residue in the pore, which was more proximal to the conduction pathway and in the electrostatic vicinity of the ion conduction pathway. The decrease of channel conductance by extracellular protons was mimicked by mutation of the outer pore histidine in K(Ca)2.2 to an asparagine residue. These data suggest that local interactions involving the outer turret histidine residues are crucial to enable high conductance openings, with protonation inhibiting current by changing pore shape.
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Affiliation(s)
- Samuel J Goodchild
- Department of Physiology and Pharmacology, University of Bristol, England, UK
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15
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Sørensen US, Strøbæk D, Christophersen P, Hougaard C, Jensen ML, Nielsen EØ, Peters D, Teuber L. Synthesis and Structure−Activity Relationship Studies of 2-(N-Substituted)-aminobenzimidazoles as Potent Negative Gating Modulators of Small Conductance Ca2+-Activated K+ Channels. J Med Chem 2008; 51:7625-34. [DOI: 10.1021/jm800809f] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
| | - Dorte Strøbæk
- NeuroSearch A/S, Pederstrupvej 93, DK-2750 Ballerup, Denmark
| | | | | | | | | | - Dan Peters
- NeuroSearch A/S, Pederstrupvej 93, DK-2750 Ballerup, Denmark
| | - Lene Teuber
- NeuroSearch A/S, Pederstrupvej 93, DK-2750 Ballerup, Denmark
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16
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Initial SAR studies on apamin-displacing 2-aminothiazole blockers of calcium-activated small conductance potassium channels. Bioorg Med Chem Lett 2008; 18:5316-9. [DOI: 10.1016/j.bmcl.2008.08.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 08/07/2008] [Accepted: 08/08/2008] [Indexed: 11/22/2022]
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17
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Preliminary SAR studies on non-apamin-displacing 4-(aminomethylaryl)pyrrazolopyrimidine K(Ca) channel blockers. Bioorg Med Chem Lett 2008; 18:5694-7. [PMID: 18824351 DOI: 10.1016/j.bmcl.2008.08.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 08/07/2008] [Accepted: 08/08/2008] [Indexed: 11/22/2022]
Abstract
An exploratory SAR study on a series of potent, non-apamin-displacing 4-(aminomethylaryl)pyrazolopyrimidine K(Ca) channel blockers is described and their selectivity against K(Ca) channel subtypes is reported. The most potent analog, 5-chloro-N-(thiophen-2-ylmethyl)pyrazolo[1,5-a]pyrimidin-7-amine (24) displayed sub-micromolar activity in both a thallium flux and whole-cell electrophysiology assay and did not displace apamin in a competitive binding study.
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Wulff H, Zhorov BS. K+ channel modulators for the treatment of neurological disorders and autoimmune diseases. Chem Rev 2008; 108:1744-73. [PMID: 18476673 PMCID: PMC2714671 DOI: 10.1021/cr078234p] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA.
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Strøbaek D, Hougaard C, Johansen TH, Sørensen US, Nielsen EØ, Nielsen KS, Taylor RDT, Pedarzani P, Christophersen P. Inhibitory Gating Modulation of Small Conductance Ca2+-Activated K+Channels by the Synthetic Compound (R)-N-(Benzimidazol-2-yl)-1,2,3,4-tetrahydro-1-naphtylamine (NS8593) Reduces Afterhyperpolarizing Current in Hippocampal CA1 Neurons. Mol Pharmacol 2006; 70:1771-82. [PMID: 16926279 DOI: 10.1124/mol.106.027110] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
SK channels are small conductance Ca(2+)-activated K(+) channels important for the control of neuronal excitability, the fine tuning of firing patterns, and the regulation of synaptic mechanisms. The classic SK channel pharmacology has largely focused on the peptide apamin, which acts extracellularly by a pore-blocking mechanism. 1-Ethyl-2-benzimidazolinone (1-EBIO) and 6,7-dichloro-1H-indole-2,3-dione 3-oxime (NS309) have been identified as positive gating modulators that increase the apparent Ca(2+) sensitivity of SK channels. In the present study, we describe inhibitory gating modulation as a novel principle for selective inhibition of SK channels. In whole-cell patch-clamp experiments, the compound (R)-N-(benzimidazol-2-yl)-1,2,3,4-tetrahydro-1-naphtylamine (NS8593) reversibly inhibited recombinant SK3-mediated currents (human SK3 and rat SK3) with potencies around 100 nM. However, in contrast to known pore blockers, NS8593 did not inhibit (125)I-apamin binding. Using excised patches, it was demonstrated that NS8593 decreased the Ca(2+) sensitivity by shifting the activation curve for Ca(2+) to the right, only slightly affecting the maximal Ca(2+)-activated SK current. NS8593 inhibited all the SK1-3 subtypes Ca(2+)-dependently (K(d) = 0.42, 0.60, and 0.73 microM, respectively, at 0.5 microM Ca(2+)), whereas the compound did not affect the Ca(2+)-activated K(+) channels of intermediate and large conductance (hIK and hBK channels, respectively). The site of action was accessible from both sides of the membrane, and the NS8593-mediated inhibition was prevented in the presence of a high concentration of the positive modulator NS309. NS8593 was further tested on mouse CA1 neurons in hippocampal slices and shown to inhibit the apaminand tubocurarine-sensitive SK-mediated afterhyperpolarizing current, at a concentration of 3 microM.
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Affiliation(s)
- Dorte Strøbaek
- NeuroSearch A/S, Pederstrupvej 93, DK 2750 Ballerup, Denmark
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