1
|
Rice CA, Stackman RW. The small conductance Ca 2+-activated K + channel activator GW542573X impairs hippocampal memory in C57BL/6J mice. Neuropharmacology 2024; 252:109960. [PMID: 38631563 DOI: 10.1016/j.neuropharm.2024.109960] [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: 01/30/2024] [Revised: 03/22/2024] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
Small conductance Ca2+-activated K+ (SK) channels, expressed throughout the CNS, are comprised of SK1, SK2 and SK3 subunits, assembled as homotetrameric or heterotetrameric proteins. SK channels expressed somatically modulate the excitability of neurons by mediating the medium component of the afterhyperpolarization. Synaptic SK channels shape excitatory postsynaptic potentials and synaptic plasticity. Such SK-mediated effects on neuronal excitability and activity-dependent synaptic strength likely underlie the modulatory influence of SK channels on memory encoding. Converging evidence indicates that several forms of long-term memory are facilitated by administration of the SK channel blocker, apamin, and impaired by administration of the pan-SK channel activator, 1-EBIO, or by overexpression of the SK2 subunit. The selective knockdown of dendritic SK2 subunits facilitates memory to a similar extent as that observed after systemic apamin. SK1 subunits co-assemble with SK2; yet the functional significance of SK1 has not been clearly defined. Here, we examined the effects of GW542573X, a drug that activates SK1 containing SK channels, as well as SK2/3, on several forms of long-term memory in male C57BL/6J mice. Our results indicate that pre-training, but not post-training, systemic GW542573X impaired object memory and fear memory in mice tested 24 h after training. Pre-training direct bilateral infusion of GW542573X into the CA1 of hippocampus impaired object memory encoding. These data suggest that systemic GW542573X impairs long-term memory. These results add to growing evidence that SK2 subunit-, and SK1 subunit-, containing SK channels can regulate behaviorally triggered synaptic plasticity necessary for encoding hippocampal-dependent memory.
Collapse
Affiliation(s)
- Claire A Rice
- Department of Psychology, Jupiter Life Science Initiative and the Stiles-Nicholson Brain Institute, Florida Atlantic University, 5353 Parkside Drive, Jupiter, FL, 33458, USA
| | - Robert W Stackman
- Department of Psychology, Jupiter Life Science Initiative and the Stiles-Nicholson Brain Institute, Florida Atlantic University, 5353 Parkside Drive, Jupiter, FL, 33458, USA.
| |
Collapse
|
2
|
Orfali R, AlFaiz A, Rahman MA, Lau L, Nam YW, Zhang M. K Ca2 and K Ca3.1 Channels in the Airways: A New Therapeutic Target. Biomedicines 2023; 11:1780. [PMID: 37509419 PMCID: PMC10376499 DOI: 10.3390/biomedicines11071780] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/08/2023] [Accepted: 06/13/2023] [Indexed: 07/30/2023] Open
Abstract
K+ channels are involved in many critical functions in lung physiology. Recently, the family of Ca2+-activated K+ channels (KCa) has received more attention, and a massive amount of effort has been devoted to developing selective medications targeting these channels. Within the family of KCa channels, three small-conductance Ca2+-activated K+ (KCa2) channel subtypes, together with the intermediate-conductance KCa3.1 channel, are voltage-independent K+ channels, and they mediate Ca2+-induced membrane hyperpolarization. Many KCa2 channel members are involved in crucial roles in physiological and pathological systems throughout the body. In this article, different subtypes of KCa2 and KCa3.1 channels and their functions in respiratory diseases are discussed. Additionally, the pharmacology of the KCa2 and KCa3.1 channels and the link between these channels and respiratory ciliary regulations will be explained in more detail. In the future, specific modulators for small or intermediate Ca2+-activated K+ channels may offer a unique therapeutic opportunity to treat muco-obstructive lung diseases.
Collapse
Affiliation(s)
- Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Ali AlFaiz
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Liz Lau
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| |
Collapse
|
3
|
Pinheiro S, Pinheiro EMC, Muri EMF, Pessôa JC, Cadorini MA, Greco SJ. Biological activities of [1,2,4]triazolo[1,5-a]pyrimidines and analogs. Med Chem Res 2020. [DOI: 10.1007/s00044-020-02609-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
4
|
Brown BM, Shim H, Christophersen P, Wulff H. Pharmacology of Small- and Intermediate-Conductance Calcium-Activated Potassium Channels. Annu Rev Pharmacol Toxicol 2019; 60:219-240. [PMID: 31337271 DOI: 10.1146/annurev-pharmtox-010919-023420] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The three small-conductance calcium-activated potassium (KCa2) channels and the related intermediate-conductance KCa3.1 channel are voltage-independent K+ channels that mediate calcium-induced membrane hyperpolarization. When intracellular calcium increases in the channel vicinity, it calcifies the flexible N lobe of the channel-bound calmodulin, which then swings over to the S4-S5 linker and opens the channel. KCa2 and KCa3.1 channels are highly druggable and offer multiple binding sites for venom peptides and small-molecule blockers as well as for positive- and negative-gating modulators. In this review, we briefly summarize the physiological role of KCa channels and then discuss the pharmacophores and the mechanism of action of the most commonly used peptidic and small-molecule KCa2 and KCa3.1 modulators. Finally, we describe the progress that has been made in advancing KCa3.1 blockers and KCa2.2 negative- and positive-gating modulators toward the clinic for neurological and cardiovascular diseases and discuss the remaining challenges.
Collapse
Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | - Heesung Shim
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| |
Collapse
|
5
|
Gol RM, Khatri TT, Barot VM. Facile Regioselective On-Water Synthesis of 4,7-Dihydropyrazolo[1,5-a]Pyrimidines and 4,7-Dihydro[1,2,4]Triazolo[1,5-a]Pyrimidines. Chem Heterocycl Compd (N Y) 2019. [DOI: 10.1007/s10593-019-02449-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
6
|
Alnajjar A, Abdelkhalik MM, Raslan MA, Ibraheem SM, Sadek KU. Synthesis of New [1,2,4]Triazolo[1,5-a
]pyrimidine Derivatives: Reactivity of 3-Amino[1,2,4]triazole towards Enaminonitriles and Enaminones. J Heterocycl Chem 2018. [DOI: 10.1002/jhet.3222] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Abdulaziz Alnajjar
- Applied Science Department, College of Technological Studies; Public Authority for Applied Education and Training; P. O. Box 42325 Safat 70654 Kuwait
| | - Mervat Mohammed Abdelkhalik
- Applied Science Department, College of Technological Studies; Public Authority for Applied Education and Training; P. O. Box 42325 Safat 70654 Kuwait
| | | | | | - Kamal Usef Sadek
- Chemistry Department, Faculty of Science; Minia University, Minia; 61519 Egypt
| |
Collapse
|
7
|
A Greener and Efficient Method for Nucleophilic Aromatic Substitution of Nitrogen-Containing Fused Heterocycles. Molecules 2018; 23:molecules23030684. [PMID: 29562645 PMCID: PMC6017854 DOI: 10.3390/molecules23030684] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/12/2018] [Accepted: 03/16/2018] [Indexed: 01/12/2023] Open
Abstract
A simple and efficient methodology for the nucleophilic aromatic substitution of nitrogen-containing fused heterocycles with interesting biological activities has been developed in an environmentally sound manner using polyethylene glycol (PEG-400) as the solvent, leading to the expected compounds in excellent yields in only five minutes.
Collapse
|
8
|
Bachl J, Sampedro D, Mayr J, Díaz Díaz D. Ultrasonication-enhanced gelation properties of a versatile amphiphilic formamidine-based gelator exhibiting both organogelation and hydrogelation abilities. Phys Chem Chem Phys 2018; 19:22981-22994. [PMID: 28816322 DOI: 10.1039/c7cp03529b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We describe the preparation of a novel amphiphilic gelator built from a formamidine core, which is able to form a variety of physical organogels and hydrogels at concentrations ranging from 15 to 150 mg mL-1. Interestingly, ultrasound treatment of isotropic solutions (i.e., gel-precursor) resulted in a remarkable enhancement of the gelation kinetics as well as the gelation scope and characteristic gel properties (e.g., critical gelation concentration, gel-to-sol transition temperature, viscoelastic moduli) in comparison to the heating-cooling protocol typically used to obtain supramolecular gels. Thermoreversibility, thixotropy, injectability and multistimuli responsiveness are some of the most relevant functionalities of these gels. Electron microscopy imaging revealed the formation of entangled networks made of fibers of nanometer diameters and micrometer lengths, with different morphological features depending on the solvent. Insights into the driving forces for molecular aggregations were obtained from FTIR, NMR, PXRD and computational studies. The results suggest a major stabilization of the fibers through additive N-HO hydrogen bonds, in combination with hydrophobic interactions, over π-π stacking interactions.
Collapse
Affiliation(s)
- Jürgen Bachl
- Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
| | - Diego Sampedro
- Departamento de Química, Universidad de La Rioja, Madre de Dios, 51, Logroño 26006, Spain
| | - Judith Mayr
- Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
| | - David Díaz Díaz
- Universität Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany. and Institute of Advanced Chemistry of Catalonia (IQAC-CSIC), Spain
| |
Collapse
|
9
|
Nam YW, Orfali R, Liu T, Yu K, Cui M, Wulff H, Zhang M. Structural insights into the potency of SK channel positive modulators. Sci Rep 2017; 7:17178. [PMID: 29214998 PMCID: PMC5719431 DOI: 10.1038/s41598-017-16607-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 11/15/2017] [Indexed: 12/26/2022] Open
Abstract
Small-conductance Ca2+-activated K+ (SK) channels play essential roles in the regulation of cellular excitability and have been implicated in neurological and cardiovascular diseases through both animal model studies and human genetic association studies. Over the past two decades, positive modulators of SK channels such as NS309 and 1-EBIO have been developed. Our previous structural studies have identified the binding pocket of 1-EBIO and NS309 that is located at the interface between the channel and calmodulin. In this study, we took advantage of four compounds with potencies varying over three orders of magnitude, including 1-EBIO, NS309, SKS-11 (6-bromo-5-methyl-1H-indole-2,3-dione-3-oxime) and SKS-14 (7-fluoro-3-(hydroxyimino)indolin-2-one). A combination of x-ray crystallographic, computational and electrophysiological approaches was utilized to investigate the interactions between the positive modulators and their binding pocket. A strong trend exists between the interaction energy of the compounds within their binding site calculated from the crystal structures, and the potency of these compounds in potentiating the SK2 channel current determined by electrophysiological recordings. Our results further reveal that the difference in potency of the positive modulators in potentiating SK2 channel activity may be attributed primarily to specific electrostatic interactions between the modulators and their binding pocket.
Collapse
Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences & Structural Biology Research Center, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences & Structural Biology Research Center, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Tingting Liu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kunqian Yu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Boston, MA, 02115, USA
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California, Davis, CA, 95616, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences & Structural Biology Research Center, Chapman University School of Pharmacy, Irvine, CA, 92618, USA.
| |
Collapse
|
10
|
Brown BM, Shim H, Zhang M, Yarov-Yarovoy V, Wulff H. Structural Determinants for the Selectivity of the Positive KCa3.1 Gating Modulator 5-Methylnaphtho[2,1- d]oxazol-2-amine (SKA-121). Mol Pharmacol 2017; 92:469-480. [PMID: 28760780 DOI: 10.1124/mol.117.109421] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/27/2017] [Indexed: 12/20/2022] Open
Abstract
Intermediate-conductance (KCa3.1) and small-conductance (KCa2) calcium-activated K+ channels are gated by calcium binding to calmodulin (CaM) molecules associated with the calmodulin-binding domain (CaM-BD) of these channels. The existing KCa activators, such as naphtho[1,2-d]thiazol-2-ylamine (SKA-31), 6,7-dichloro-1H-indole-2,3-dione 3-oxime (NS309), and 1-ethylbenzimidazolin-2-one (EBIO), activate both channel types with similar potencies. In a previous chemistry effort, we optimized the benzothiazole pharmacophore of SKA-31 toward KCa3.1 selectivity and identified 5-methylnaphtho[2,1-d]oxazol-2-amine (SKA-121), which exhibits 40-fold selectivity for KCa3.1 over KCa2.3. To understand why introduction of a single CH3 group in five-position of the benzothiazole/oxazole system could achieve such a gain in selectivity for KCa3.1 over KCa2.3, we first localized the binding site of the benzothiazoles/oxazoles to the CaM-BD/CaM interface and then used computational modeling software to generate models of the KCa3.1 and KCa2.3 CaM-BD/CaM complexes with SKA-121. Based on a combination of mutagenesis and structural modeling, we suggest that all benzothiazole/oxazole-type KCa activators bind relatively "deep" in the CaM-BD/CaM interface and hydrogen bond with E54 on CaM. In KCa3.1, SKA-121 forms an additional hydrogen bond network with R362. In contrast, NS309 sits more "forward" and directly hydrogen bonds with R362 in KCa3.1. Mutating R362 to serine, the corresponding residue in KCa2.3 reduces the potency of SKA-121 by 7-fold, suggesting that R362 is responsible for the generally greater potency of KCa activators on KCa3.1. The increase in SKA-121's KCa3.1 selectivity compared with its parent, SKA-31, seems to be due to better overall shape complementarity and hydrophobic interactions with S372 and M368 on KCa3.1 and M72 on CaM at the KCa3.1-CaM-BD/CaM interface.
Collapse
Affiliation(s)
- Brandon M Brown
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Heesung Shim
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Miao Zhang
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Vladimir Yarov-Yarovoy
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| | - Heike Wulff
- Department of Pharmacology (B.M.B., H.S., H.W.), Department of Physiology and Membrane Biology (V.Y.-Y.), School of Medicine, and Department of Chemistry (H.S.), University of California, Davis, California; and Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, California (M.Z.)
| |
Collapse
|
11
|
Honrath B, Krabbendam IE, Culmsee C, Dolga AM. Small conductance Ca 2+-activated K + channels in the plasma membrane, mitochondria and the ER: Pharmacology and implications in neuronal diseases. Neurochem Int 2017; 109:13-23. [PMID: 28511953 DOI: 10.1016/j.neuint.2017.05.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/24/2017] [Accepted: 05/08/2017] [Indexed: 12/14/2022]
Abstract
Ca2+-activated K+ (KCa) channels regulate after-hyperpolarization in many types of neurons in the central and peripheral nervous system. Small conductance Ca2+-activated K+ (KCa2/SK) channels, a subfamily of KCa channels, are widely expressed in the nervous system, and in the cardiovascular system. Voltage-independent SK channels are activated by alterations in intracellular Ca2+ ([Ca2+]i) which facilitates the opening of these channels through binding of Ca2+ to calmodulin that is constitutively bound to the SK2 C-terminus. In neurons, SK channels regulate synaptic plasticity and [Ca2+]i homeostasis, and a number of recent studies elaborated on the emerging neuroprotective potential of SK channel activation in conditions of excitotoxicity and cerebral ischemia, as well as endoplasmic reticulum (ER) stress and oxidative cell death. Recently, SK channels were discovered in the inner mitochondrial membrane and in the membrane of the endoplasmic reticulum which sheds new light on the underlying molecular mechanisms and pathways involved in SK channel-mediated protective effects. In this review, we will discuss the protective properties of pharmacological SK channel modulation with particular emphasis on intracellularly located SK channels as potential therapeutic targets in paradigms of neuronal dysfunction.
Collapse
Affiliation(s)
- Birgit Honrath
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
| |
Collapse
|
12
|
|
13
|
Christophersen P, Wulff H. Pharmacological gating modulation of small- and intermediate-conductance Ca(2+)-activated K(+) channels (KCa2.x and KCa3.1). Channels (Austin) 2015. [PMID: 26217968 DOI: 10.1080/19336950.2015.1071748] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
This short review discusses pharmacological modulation of the opening/closing properties (gating) of small- and intermediate-conductance Ca(2+)-activated K(+) channels (KCa2 and KCa3.1) with special focus on mechanisms-of-action, selectivity, binding sites, and therapeutic potentials. Despite KCa channel gating-modulation being a relatively novel field in drug discovery, efforts in this area have already revealed a surprising plethora of pharmacological sites-of-actions and channel subtype selectivity exerted by different chemical classes. The currently published positive modulators show that such molecules are potentially useful for the treatment of various neurodegenerative disorders such as ataxia, alcohol dependence, and epilepsy as well as hypertension. The negative KCa2 modulators are very effective agents for atrial fibrillation. The prediction is that further unraveling of the molecular details of gating pharmacology will allow for the design of even more potent and subtype selective KCa modulators entering into drug development for these indications.
Collapse
Affiliation(s)
| | - Heike Wulff
- b Department of Pharmacology ; University of California, Davis ; Davis , CA USA
| |
Collapse
|
14
|
Oliván-Viguera A, Valero MS, Coleman N, Brown BM, Laría C, Murillo MD, Gálvez JA, Díaz-de-Villegas MD, Wulff H, Badorrey R, Köhler R. A novel pan-negative-gating modulator of KCa2/3 channels, fluoro-di-benzoate, RA-2, inhibits endothelium-derived hyperpolarization-type relaxation in coronary artery and produces bradycardia in vivo. Mol Pharmacol 2014; 87:338-48. [PMID: 25468883 DOI: 10.1124/mol.114.095745] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Small/intermediate conductance KCa channels (KCa2/3) are Ca(2+)/calmodulin regulated K(+) channels that produce membrane hyperpolarization and shape neurologic, epithelial, cardiovascular, and immunologic functions. Moreover, they emerged as therapeutic targets to treat cardiovascular disease, chronic inflammation, and some cancers. Here, we aimed to generate a new pharmacophore for negative-gating modulation of KCa2/3 channels. We synthesized a series of mono- and dibenzoates and identified three dibenzoates [1,3-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate) (RA-2), 1,2-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate), and 1,4-phenylenebis(methylene) bis(3-fluoro-4-hydroxybenzoate)] with inhibitory efficacy as determined by patch clamp. Among them, RA-2 was the most drug-like and inhibited human KCa3.1 with an IC50 of 17 nM and all three human KCa2 subtypes with similar potencies. RA-2 at 100 nM right-shifted the KCa3.1 concentration-response curve for Ca(2+) activation. The positive-gating modulator naphtho[1,2-d]thiazol-2-ylamine (SKA-31) reversed channel inhibition at nanomolar RA-2 concentrations. RA-2 had no considerable blocking effects on distantly related large-conductance KCa1.1, Kv1.2/1.3, Kv7.4, hERG, or inwardly rectifying K(+) channels. In isometric myography on porcine coronary arteries, RA-2 inhibited bradykinin-induced endothelium-derived hyperpolarization (EDH)-type relaxation in U46619-precontracted rings. Blood pressure telemetry in mice showed that intraperitoneal application of RA-2 (≤100 mg/kg) did not increase blood pressure or cause gross behavioral deficits. However, RA-2 decreased heart rate by ≈145 beats per minute, which was not seen in KCa3.1(-/-) mice. In conclusion, we identified the KCa2/3-negative-gating modulator, RA-2, as a new pharmacophore with nanomolar potency. RA-2 may be of use to generate structurally new types of negative-gating modulators that could help to define the physiologic and pathomechanistic roles of KCa2/3 in the vasculature, central nervous system, and during inflammation in vivo.
Collapse
Affiliation(s)
- Aida Oliván-Viguera
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Marta Sofía Valero
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Nicole Coleman
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Brandon M Brown
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Celia Laría
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - María Divina Murillo
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - José A Gálvez
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - María D Díaz-de-Villegas
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Heike Wulff
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Ramón Badorrey
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.)
| | - Ralf Köhler
- Aragon Institute of Health Sciences, Zaragoza, Spain (A.O.-V., R.K.); GIMACES, Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V., C.L.); Department of Pharmacology, School of Medicine, University of California Davis, Davis, California (N.C., B.M.B, H.W.); Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Zaragoza, Spain (M.D.M.); Departamento de Catálisis y Procesos Catalíticos, Instituto de Síntesis Química y Catálisis Homogénea, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Zaragoza, Spain (M.D.D.-V., J.A.G., R.B.); and Fundación Agencia Aragonesa para la Investigación y Desarrollo (R.K.).
| |
Collapse
|
15
|
Garneau L, Klein H, Lavoie MF, Brochiero E, Parent L, Sauvé R. Aromatic-aromatic interactions between residues in KCa3.1 pore helix and S5 transmembrane segment control the channel gating process. ACTA ACUST UNITED AC 2014; 143:289-307. [PMID: 24470490 PMCID: PMC4001770 DOI: 10.1085/jgp.201311097] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Interactions between aromatic amino acid residues in the pore helix and S5 transmembrane domain control gating of the Ca2+-activated potassium channel KCa3.1. The Ca2+-activated potassium channel KCa3.1 is emerging as a therapeutic target for a large variety of health disorders. One distinguishing feature of KCa3.1 is that the channel open probability at saturating Ca2+ concentrations (Pomax) is low, typically 0.1–0.2 for KCa3.1 wild type. This observation argues for the binding of Ca2+ to the calmodulin (CaM)–KCa3.1 complex, promoting the formation of a preopen closed-state configuration leading to channel opening. We have previously shown that the KCa3.1 active gate is most likely located at the level of the selectivity filter. As Ca2+-dependent gating of KCa3.1 originates from the binding of Ca2+ to CaM in the C terminus, the hypothesis of a gate located at the level of the selectivity filter requires that the conformational change initiated in the C terminus be transmitted to the S5 and S6 transmembrane helices, with a resulting effect on the channel pore helix directly connected to the selectivity filter. A study was thus undertaken to determine to what extent the interactions between the channel pore helix with the S5 and S6 transmembrane segments contribute to KCa3.1 gating. Molecular dynamics simulations first revealed that the largest contact area between the pore helix and the S5 plus S6 transmembrane helices involves residue F248 at the C-terminal end of the pore helix. Unitary current recordings next confirmed that modulating aromatic–aromatic interactions between F248 and W216 of the S5 transmembrane helical segment and/or perturbing the interactions between F248 and residues in S6 surrounding the glycine hinge G274 cause important changes in Pomax. This work thus provides the first evidence for a key contribution of the pore helix in setting Pomax by stabilizing the channel closed configuration through aromatic–aromatic interactions involving F248 of the pore helix. We propose that the interface pore helix/S5 constitutes a promising site for designing KCa3.1 potentiators.
Collapse
Affiliation(s)
- Line Garneau
- Department of Physiology and Membrane Protein Research Group, 2 Centre de recherche du Centre hospitalier de l'Université de Montréal, and 3 Department of Medicine, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
| | | | | | | | | | | |
Collapse
|
16
|
Coleman N, Brown BM, Oliván-Viguera A, Singh V, Olmstead MM, Valero MS, Köhler R, Wulff H. New positive Ca2+-activated K+ channel gating modulators with selectivity for KCa3.1. Mol Pharmacol 2014; 86:342-57. [PMID: 24958817 DOI: 10.1124/mol.114.093286] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Small-conductance (KCa2) and intermediate-conductance (KCa3.1) calcium-activated K(+) channels are voltage-independent and share a common calcium/calmodulin-mediated gating mechanism. Existing positive gating modulators like EBIO, NS309, or SKA-31 activate both KCa2 and KCa3.1 channels with similar potency or, as in the case of CyPPA and NS13001, selectively activate KCa2.2 and KCa2.3 channels. We performed a structure-activity relationship (SAR) study with the aim of optimizing the benzothiazole pharmacophore of SKA-31 toward KCa3.1 selectivity. We identified SKA-111 (5-methylnaphtho[1,2-d]thiazol-2-amine), which displays 123-fold selectivity for KCa3.1 (EC50 111 ± 27 nM) over KCa2.3 (EC50 13.7 ± 6.9 μM), and SKA-121 (5-methylnaphtho[2,1-d]oxazol-2-amine), which displays 41-fold selectivity for KCa3.1 (EC50 109 nM ± 14 nM) over KCa2.3 (EC50 4.4 ± 1.6 μM). Both compounds are 200- to 400-fold selective over representative KV (KV1.3, KV2.1, KV3.1, and KV11.1), NaV (NaV1.2, NaV1.4, NaV1.5, and NaV1.7), as well as CaV1.2 channels. SKA-121 is a typical positive-gating modulator and shifts the calcium-concentration response curve of KCa3.1 to the left. In blood pressure telemetry experiments, SKA-121 (100 mg/kg i.p.) significantly lowered mean arterial blood pressure in normotensive and hypertensive wild-type but not in KCa3.1(-/-) mice. SKA-111, which was found in pharmacokinetic experiments to have a much longer half-life and to be much more brain penetrant than SKA-121, not only lowered blood pressure but also drastically reduced heart rate, presumably through cardiac and neuronal KCa2 activation when dosed at 100 mg/kg. In conclusion, with SKA-121, we generated a KCa3.1-specific positive gating modulator suitable for further exploring the therapeutical potential of KCa3.1 activation.
Collapse
Affiliation(s)
- Nichole Coleman
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Brandon M Brown
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Aida Oliván-Viguera
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Vikrant Singh
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Marilyn M Olmstead
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Marta Sofia Valero
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Ralf Köhler
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| | - Heike Wulff
- Department of Pharmacology (N.C., B.M.B., V.S., H.W.), School of Medicine, and Department of Chemistry (M.M.O.), University of California, Davis, California; Aragon Institute of Health Sciences, Instituto de Investigación Sanitaria, Fundación Agencia Aragonesa para la Investigación y el Desarrollo, Zaragoza, Spain (A.O.-V., R.K.); and Grupo de Investigación del Medio Ambiente del Centro de Estudios Superiores, Faculty of Health Sciences, Universidad San Jorge, Villanueva de Gállego, Spain (M.S.V.)
| |
Collapse
|
17
|
Jenkins DP, Yu W, Brown BM, Løjkner LD, Wulff H. Development of a QPatch automated electrophysiology assay for identifying KCa3.1 inhibitors and activators. Assay Drug Dev Technol 2013; 11:551-60. [PMID: 24351043 PMCID: PMC3870577 DOI: 10.1089/adt.2013.543] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The intermediate-conductance Ca(2+)-activated K(+) channel KCa3.1 (also known as KCNN4, IK1, or the Gárdos channel) plays an important role in the activation of T and B cells, mast cells, macrophages, and microglia by regulating membrane potential, cellular volume, and calcium signaling. KCa3.1 is further involved in the proliferation of dedifferentiated vascular smooth muscle cells and fibroblast and endothelium-derived hyperpolarization responses in the vascular endothelium. Accordingly, KCa3.1 inhibitors are therapeutically interesting as immunosuppressants and for the treatment of a wide range of fibroproliferative disorders, whereas KCa3.1 activators constitute a potential new class of endothelial function preserving antihypertensives. Here, we report the development of QPatch assays for both KCa3.1 inhibitors and activators. During assay optimization, the Ca(2+) sensitivity of KCa3.1 was studied using varying intracellular Ca(2+) concentrations. A free Ca(2+) concentration of 1 μM was chosen to optimally test inhibitors. To identify activators, which generally act as positive gating modulators, a lower Ca(2+) concentration (∼200 nM) was used. The QPatch results were benchmarked against manual patch-clamp electrophysiology by determining the potency of several commonly used KCa3.1 inhibitors (TRAM-34, NS6180, ChTX) and activators (EBIO, riluzole, SKA-31). Collectively, our results demonstrate that the QPatch provides a comparable but much faster approach to study compound interactions with KCa3.1 channels in a robust and reliable assay.
Collapse
Affiliation(s)
| | - Weifeng Yu
- Sophion Bioscience, Inc., North Brunswick, New Jersey
| | - Brandon M. Brown
- Department of Pharmacology, University of California, Davis, California
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California
| |
Collapse
|
18
|
Lam J, Coleman N, Garing ALA, Wulff H. The therapeutic potential of small-conductance KCa2 channels in neurodegenerative and psychiatric diseases. Expert Opin Ther Targets 2013; 17:1203-20. [PMID: 23883298 DOI: 10.1517/14728222.2013.823161] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION KCa2 or small-conductance Ca(2+)-activated K(+) channels (SK) are expressed in many areas of the central nervous system where they participate in the regulation of neuronal afterhyperpolarization and excitability, and also serve as negative feedback regulators on the glutamate-NMDA pathway. AREAS COVERED This review focuses on the role of KCa2 channels in learning and memory and their potential as therapeutic targets for Alzheimer's and Parkinson's disease, ataxia, schizophrenia and alcohol dependence. EXPERT OPINION There currently exists relatively solid evidence supporting the use of KCa2 activators for ataxia. Genetic KCa2 channel suppression in deep cerebellar neurons induces ataxia, while KCa2 activators like 1-EBIO, SKA-31 and NS13001 improve motor deficits in mouse models of episodic ataxia (EA) and spinal cerebellar ataxia (SCA). Use of KCa2 activators for ataxia is further supported by a report that riluzole improves ataxia in a small clinical trial. Based on accumulating literature evidence, KCa2 activators further appear attractive for the treatment of alcohol dependence and withdrawal. Regarding Alzheimer's disease, Parkinson's disease and schizophrenia, further research, including long-term studies in disease relevant animal models, will be needed to determine whether KCa2 channels constitute valid targets and whether activators or inhibitors would be needed to positively affect disease outcomes.
Collapse
Affiliation(s)
- Jenny Lam
- University of California, Davis, Department of Pharmacology , 451 Health Sciences Drive, Genome and Biomedical Sciences Facility Room 3502, Davis, CA 95616 , USA +1 530 754 6135 ; +1 530 752 7710 ;
| | | | | | | |
Collapse
|
19
|
Endothelial small-conductance and intermediate-conductance KCa channels: an update on their pharmacology and usefulness as cardiovascular targets. J Cardiovasc Pharmacol 2013; 61:102-12. [PMID: 23107876 DOI: 10.1097/fjc.0b013e318279ba20] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Most cardiovascular researchers are familiar with intermediate-conductance KCa3.1 and small-conductance KCa2.3 channels because of their contribution to endothelium-derived hyperpolarization. However, to immunologists and neuroscientists, these channels are primarily known for their role in lymphocyte activation and neuronal excitability. KCa3.1 is involved in the proliferation and migration of T cells, B cells, mast cells, macrophages, fibroblasts, and dedifferentiated vascular smooth muscle cells and is, therefore, being pursued as a potential target for use in asthma, immunosuppression, and fibroproliferative disorders. In contrast, the 3 KCa2 channels (KCa2.1, KCa2.2, and KCa2.3) contribute to the neuronal medium afterhyperpolarization and, depending on the type of neuron, are involved in determining firing rates and frequencies or in regulating bursting. KCa2 activators are accordingly being studied as potential therapeutics for ataxia and epilepsy, whereas KCa2 channel inhibitors like apamin have long been known to improve learning and memory in rodents. Given this background, we review the recent discoveries of novel KCa3.1 and KCa2.3 modulators and critically assess the potential of KCa activators for the treatment of diabetes and cardiovascular diseases by improving endothelium-derived hyperpolarizations.
Collapse
|
20
|
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.
Collapse
Affiliation(s)
- Donglai Yang
- Department of Chemistry, University College London, Gower Street, London WC1E 6BT, UK
| | | | | | | |
Collapse
|
21
|
Balut CM, Hamilton KL, Devor DC. Trafficking of intermediate (KCa3.1) and small (KCa2.x) conductance, Ca(2+)-activated K(+) channels: a novel target for medicinal chemistry efforts? ChemMedChem 2012; 7:1741-55. [PMID: 22887933 DOI: 10.1002/cmdc.201200226] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 07/09/2012] [Indexed: 12/22/2022]
Abstract
Ca(2+)-activated K(+) (KCa) channels play a pivotal role in the physiology of a wide variety of tissues and disease states, including vascular endothelia, secretory epithelia, certain cancers, red blood cells (RBC), neurons, and immune cells. Such widespread involvement has generated an intense interest in elucidating the function and regulation of these channels, with the goal of developing pharmacological strategies aimed at selective modulation of KCa channels in various disease states. Herein we give an overview of the molecular and functional properties of these channels and their therapeutic importance. We discuss the achievements made in designing pharmacological tools that control the function of KCa channels by modulating their gating properties. Moreover, this review discusses the recent advances in our understanding of KCa channel assembly and anterograde trafficking toward the plasma membrane, the micro-domains in which these channels are expressed within the cell, and finally the retrograde trafficking routes these channels take following endocytosis. As the regulation of intracellular trafficking by agonists as well as the protein-protein interactions that modify these events continue to be explored, we anticipate this will open new therapeutic avenues for the targeting of these channels based on the pharmacological modulation of KCa channel density at the plasma membrane.
Collapse
Affiliation(s)
- Corina M Balut
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | | | | |
Collapse
|