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Lee N, Kim S, Lee NY, Jo H, Jeong P, Pagire HS, Pagire SH, Ahn JH, Jin MS, Park CS. Activation mechanism and novel binding sites of the BK Ca channel activator CTIBD. Life Sci Alliance 2024; 7:e202402621. [PMID: 39089879 PMCID: PMC11294680 DOI: 10.26508/lsa.202402621] [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: 01/26/2024] [Revised: 07/12/2024] [Accepted: 07/15/2024] [Indexed: 08/04/2024] Open
Abstract
The large-conductance calcium-activated potassium (BKCa) channel, which is crucial for urinary bladder smooth muscle relaxation, is a potential target for overactive bladder treatment. Our prior work unveiled CTIBD as a promising BKCa channel activator, altering V 1/2 and G max This study investigates CTIBD's activation mechanism, revealing its independence from the Ca2+ and membrane voltage sensing of the BKCa channel. Cryo-electron microscopy disclosed that two CTIBD molecules bind to hydrophobic regions on the extracellular side of the lipid bilayer. Key residues (W22, W203, and F266) are important for CTIBD binding, and their replacement with alanine reduces CTIBD-mediated channel activation. The triple-mutant (W22A/W203A/F266A) channel showed the smallest V 1/2 shift with a minimal impact on activation and deactivation kinetics by CTIBD. At the single-channel level, CTIBD treatment was much less effective at increasing P o in the triple mutant, mainly because of a drastically increased dissociation rate compared with the WT. These findings highlight CTIBD's mechanism, offering crucial insights for developing small-molecule treatments for BKCa-related pathophysiological conditions.
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Affiliation(s)
- Narasaem Lee
- https://ror.org/024kbgz78 School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Subin Kim
- https://ror.org/024kbgz78 School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Na Young Lee
- https://ror.org/024kbgz78 School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Heeji Jo
- https://ror.org/024kbgz78 School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | | | - Haushabhau S Pagire
- https://ror.org/024kbgz78 Department of Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Suvarna H Pagire
- https://ror.org/024kbgz78 Department of Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Jin Hee Ahn
- https://ror.org/024kbgz78 Department of Chemistry, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Mi Sun Jin
- https://ror.org/024kbgz78 School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Chul-Seung Park
- https://ror.org/024kbgz78 School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
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2
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Moldenhauer HJ, Tammen K, Meredith AL. Structural mapping of patient-associated KCNMA1 gene variants. Biophys J 2024; 123:1984-2000. [PMID: 38042986 DOI: 10.1016/j.bpj.2023.11.3404] [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: 09/08/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 12/04/2023] Open
Abstract
KCNMA1-linked channelopathy is a neurological disorder characterized by seizures, motor abnormalities, and neurodevelopmental disabilities. The disease mechanisms are predicted to result from alterations in KCNMA1-encoded BK K+ channel activity; however, only a subset of the patient-associated variants have been functionally studied. The localization of these variants within the tertiary structure or evaluation by pathogenicity algorithms has not been systematically assessed. In this study, 82 nonsynonymous patient-associated KCNMA1 variants were mapped within the BK channel protein. Fifty-three variants localized within cryoelectron microscopy-resolved structures, including 21 classified as either gain of function (GOF) or loss of function (LOF) in BK channel activity. Clusters of LOF variants were identified in the pore, the AC region (RCK1), and near the Ca2+ bowl (RCK2), overlapping with sites of pharmacological or endogenous modulation. However, no clustering was found for GOF variants. To further understand variants of uncertain significance (VUSs), assessments by multiple standard pathogenicity algorithms were compared, and new thresholds for sensitivity and specificity were established from confirmed GOF and LOF variants. An ensemble algorithm was constructed (KCNMA1 meta score (KMS)), consisting of a weighted summation of this trained dataset combined with a structural component derived from the Ca2+-bound and unbound BK channels. KMS assessment differed from the highest-performing individual algorithm (REVEL) at 10 VUS residues, and a subset were studied further by electrophysiology in HEK293 cells. M578T, E656A, and D965V (KMS+;REVEL-) were confirmed to alter BK channel properties in voltage-clamp recordings, and D800Y (KMS-;REVEL+) was assessed as benign under the test conditions. However, KMS failed to accurately assess K457E. These combined results reveal the distribution of potentially disease-causing KCNMA1 variants within BK channel functional domains and pathogenicity evaluation for VUSs, suggesting strategies for improving channel-level predictions in future studies by building on ensemble algorithms such as KMS.
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Affiliation(s)
- Hans J Moldenhauer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Kelly Tammen
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland.
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3
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Harlow RC, Pea GA, Broyhill SE, Patro A, Bromert KH, Stewart RH, Heaps CL, Castorena-Gonzalez JA, Dongaonkar RM, Zawieja SD. Loss of anoctamin 1 reveals a subtle role for BK channels in lymphatic muscle action potentials. J Physiol 2024; 602:3351-3373. [PMID: 38704841 PMCID: PMC11250503 DOI: 10.1113/jp285459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 04/11/2024] [Indexed: 05/07/2024] Open
Abstract
Ca2+ signalling plays a crucial role in determining lymphatic muscle cell excitability and contractility through its interaction with the Ca2+-activated Cl- channel anoctamin 1 (ANO1). In contrast, the large-conductance (BK) Ca2+-activated K+ channel (KCa) and other KCa channels have prominent vasodilatory actions by hyperpolarizing vascular smooth muscle cells. Here, we assessed the expression and contribution of the KCa family to mouse and rat lymphatic collecting vessel contractile function. The BK channel was the only KCa channel consistently expressed in fluorescence-activated cell sorting-purified mouse lymphatic muscle cell lymphatic muscle cells. We used a pharmacological inhibitor of BK channels, iberiotoxin, and small-conductance Ca2+-activated K+ channels, apamin, to inhibit KCa channels acutely in ex vivo isobaric myography experiments and intracellular membrane potential recordings. In basal conditions, BK channel inhibition had little to no effect on either mouse inguinal-axillary lymphatic vessel (MIALV) or rat mesenteric lymphatic vessel contractions or action potentials (APs). We also tested BK channel inhibition under loss of ANO1 either by genetic ablation (Myh11CreERT2-Ano1 fl/fl, Ano1ismKO) or by pharmacological inhibition with Ani9. In both Ano1ismKO MIALVs and Ani9-pretreated MIALVs, inhibition of BK channels increased contraction amplitude, increased peak AP and broadened the peak of the AP spike. In rat mesenteric lymphatic vessels, BK channel inhibition also abolished the characteristic post-spike notch, which was exaggerated with ANO1 inhibition, and significantly increased the peak potential and broadened the AP spike. We conclude that BK channels are present and functional on mouse and rat lymphatic muscle cells but are otherwise masked by the dominance of ANO1. KEY POINTS: Mouse and rat lymphatic muscle cells express functional BK channels. BK channels make little contribution to either rat or mouse lymphatic collecting vessel contractile function in basal conditions across a physiological pressure range. ANO1 limits the peak membrane potential achieved in the action potential and sets a plateau potential limiting the voltage-dependent activation of BK. BK channels are activated when ANO1 is absent or blocked and slightly impair contractile strength by reducing the peak membrane potential achieved in the action potential spike and accelerating the post-spike repolarization.
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Affiliation(s)
- Rebecca C Harlow
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | - Grace A Pea
- Department of Medical Pharmacology & Physiology, University of Missouri, Columbia, MO, USA
| | - Sarah E Broyhill
- Department of Medical Pharmacology & Physiology, University of Missouri, Columbia, MO, USA
| | - Advaya Patro
- Department of Medical Pharmacology & Physiology, University of Missouri, Columbia, MO, USA
| | - Karen H Bromert
- Department of Medical Pharmacology & Physiology, University of Missouri, Columbia, MO, USA
| | - Randolph H Stewart
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | - Cristine L Heaps
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | | | - Ranjeet M Dongaonkar
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX, USA
| | - Scott D Zawieja
- Department of Medical Pharmacology & Physiology, University of Missouri, Columbia, MO, USA
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Son NT, Gianibbi B, Panti A, Spiga O, Bastos JK, Fusi F. Vasorelaxant Activity of (2S)-Sakuranetin and Other Flavonoids Isolated from the Green Propolis of the Caatinga Mimosa tenuiflora. PLANTA MEDICA 2024; 90:454-468. [PMID: 38599606 DOI: 10.1055/a-2294-7042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Some in vitro and in vivo evidence is consistent with the cardiovascular beneficial activity of propolis. As the single actors responsible for this effect have never been identified, an in-depth investigation of flavonoids isolated from the green propolis of the Caatinga Mimosa tenuiflora was performed and their mechanism of action was described. A comprehensive electrophysiology, functional, and molecular docking approach was applied. Most flavanones and flavones were effective CaV1.2 channel blockers with a potency order of (2S)-sakuranetin > eriodictyol-7,3'-methyl ether > quercetin 3-methyl ether > 5,4'-dihydroxy-6,7-dimethoxyflavanone > santin > axillarin > penduletin > kumatakenin, ermanin and viscosine being weak or modest stimulators. Except for eriodictyol 5-O-methyl ether, all the flavonoids were also effective spasmolytic agents of vascular rings, kumatakenin and viscosine also showing an endothelium-dependent activity. (2S)-Sakuranetin also stimulated KCa1.1 channels both in single myocytes and vascular rings. In silico analysis provided interesting insights into the mode of action of (2S)-sakuranetin within both CaV1.2 and KCa1.1 channels. The green propolis of the Caatinga Mimosa tenuiflora is a valuable source of multi-target vasoactive flavonoids: this evidence reinforces its nutraceutical value in the cardiovascular disease prevention arena.
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Affiliation(s)
- Ninh The Son
- Institute of Chemistry, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
- Department of Chemistry, Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Caugiay, Hanoi, Vietnam
| | - Beatrice Gianibbi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Siena, Italy
| | - Alice Panti
- Dipartimento di Scienze della Vita, Università di Siena, Siena, Italy
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Siena, Italy
| | - Jairo Kenupp Bastos
- School of Pharmaceutical Sciences of Ribeirão Preto, Ribeirão Preto, University of São Paulo, Ribeirão Preto-SP, Brazil
| | - Fabio Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Siena, Italy
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5
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Son NT, Gianibbi B, Panti A, Spiga O, Bastos JK, Fusi F. 3,3'-O-dimethylquercetin: A bi-functional vasodilator isolated from green propolis of the Caatinga Mimosa tenuiflora. Eur J Pharmacol 2024; 967:176400. [PMID: 38331336 DOI: 10.1016/j.ejphar.2024.176400] [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: 09/19/2023] [Revised: 01/29/2024] [Accepted: 02/06/2024] [Indexed: 02/10/2024]
Abstract
In the search for novel, bi-functional compounds acting as CaV1.2 channel blockers and K+ channel stimulators, which represent an effective therapy for hypertension, 3,3'-O-dimethylquercetin was isolated for the first time from Brazilian Caatinga green propolis. Its effects were investigated through electrophysiological, functional, and computational approaches. In rat tail artery myocytes, 3,3'-O-dimethylquercetin blocked Ba2+ currents through CaV1.2 channels (IBa1.2) in a concentration-dependent manner, with the inhibition being reversed upon washout. The compound also shifted the voltage dependence of the steady-state inactivation curve to more negative potentials without affecting the slope of the inactivation and activation curves. Furthermore, the flavonoid stimulated KCa1.1 channel currents (IKCa1.1). In silico simulations provided additional evidence for the binding of 3,3'-O-dimethylquercetin to KCa1.1 and CaV1.2 channels and elucidated its mechanism of action. In depolarized rat tail artery rings, the flavonoid induced a concentration-dependent relaxation. Moreover, in rat aorta rings its antispasmodic effect was inversely related to the transmembrane K+ gradient. In conclusion, 3,3'-O-dimethylquercetin demonstrates effective in vitro vasodilatory properties, encouraging the exploration of its scaffold to develop novel derivatives for potential use in the treatment of hypertension.
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Affiliation(s)
- Ninh The Son
- School of Pharmaceutical Sciences of Ribeirão Preto, Ribeirão Preto, University of São Paulo, Avenida Professor Doutor Zeferino Vaz, S/N, 14040-903, Ribeirão Preto-SP, Brazil; Institute of Chemistry, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Caugiay, Hanoi, 10000, Vietnam; Department of Chemistry, Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Caugiay, Hanoi, 10000, Vietnam
| | - Beatrice Gianibbi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100, Siena, Italy
| | - Alice Panti
- Dipartimento di Scienze della Vita, Università di Siena, Via A. Moro 2, 53100, Siena, Italy
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100, Siena, Italy
| | - Jairo Kenupp Bastos
- School of Pharmaceutical Sciences of Ribeirão Preto, Ribeirão Preto, University of São Paulo, Avenida Professor Doutor Zeferino Vaz, S/N, 14040-903, Ribeirão Preto-SP, Brazil.
| | - Fabio Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100, Siena, Italy.
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6
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Kendall RL, Holian A. Lysosomal BK channels facilitate silica-induced inflammation in macrophages. Inhal Toxicol 2024; 36:31-43. [PMID: 38261520 PMCID: PMC11080613 DOI: 10.1080/08958378.2024.2305112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/09/2024] [Indexed: 01/25/2024]
Abstract
BACKGROUND Lysosomal ion channels are proposed therapeutic targets for a number of diseases, including those driven by NLRP3 inflammasome-mediated inflammation. Here, the specific role of the lysosomal big conductance Ca2+-activated K+ (BK) channel was evaluated in a silica model of inflammation in murine macrophages. A specific-inhibitor of BK channel function, paxilline (PAX), and activators NS11021 and NS1619 were utilized to evaluate the role of lysosomal BK channel activity in silica-induced lysosomal membrane permeabilization (LMP) and NLRP3 inflammasome activation resulting in IL-1β release. METHODS Murine macrophages were exposed in vitro to crystalline silica following pretreatment with BK channel inhibitors or activators and LMP, cell death, and IL-1β release were assessed. In addition, the effect of PAX treatment on silica-induced cytosolic K+ decrease was measured. Finally, the effects of BK channel modifiers on lysosomal pH, proteolytic activity, and cholesterol transport were also evaluated. RESULTS PAX pretreatment significantly attenuated silica-induced cell death and IL-1β release. PAX caused an increase in lysosomal pH and decrease in lysosomal proteolytic activity. PAX also caused a significant accumulation of lysosomal cholesterol. BK channel activators NS11021 and NS1619 increased silica-induced cell death and IL-1β release. BK channel activation also caused a decrease in lysosomal pH and increase in lysosomal proteolytic function as well as a decrease in cholesterol accumulation. CONCLUSION Taken together, these results demonstrate that inhibiting lysosomal BK channel activity with PAX effectively reduced silica-induced cell death and IL-1β release. Blocking cytosolic K+ entry into the lysosome prevented LMP through the decrease of lysosomal acidification and proteolytic function and increase in lysosomal cholesterol.
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Affiliation(s)
- Rebekah L Kendall
- Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
| | - Andrij Holian
- Center for Environmental Health Sciences, University of Montana, Missoula, MT, USA
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7
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Moldenhauer HJ, Tammen K, Meredith AL. Structural mapping of patient-associated KCNMA1 gene variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.27.550850. [PMID: 37546746 PMCID: PMC10402178 DOI: 10.1101/2023.07.27.550850] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
KCNMA1-linked channelopathy is a neurological disorder characterized by seizures, motor abnormalities, and neurodevelopmental disabilities. The disease mechanisms are predicted to result from alterations in KCNMA1-encoded BK K+ channel activity; however, only a subset of the patient-associated variants have been functionally studied. The localization of these variants within the tertiary structure or evaluation by pathogenicity algorithms has not been systematically assessed. In this study, 82 nonsynonymous patient-associated KCNMA1 variants were mapped within the BK channel protein. Fifty-three variants localized within cryo-EM resolved structures, including 21 classified as either gain-of-function (GOF) or loss-of-function (LOF) in BK channel activity. Clusters of LOF variants were identified in the pore, the AC region (RCK1), and near the Ca 2+ bowl (RCK2), overlapping with sites of pharmacological or endogenous modulation. However, no clustering was found for GOF variants. To further understand variants of uncertain significance (VUS), assessments by multiple standard pathogenicity algorithms were compared, and new thresholds for sensitivity and specificity were established from confirmed GOF and LOF variants. An ensemble algorithm was constructed (KCNMA1 Meta Score), consisting of a weighted summation of this trained dataset combined with a structural component derived from the Ca 2+ bound and unbound BK channels. KMS assessment differed from the highest performing individual algorithm (REVEL) at 10 VUS residues, and a subset were studied further by electrophysiology in HEK293 cells. M578T, E656A, and D965V (KMS+;REVEL-) were confirmed to alter BK channel properties in voltage-clamp recordings, and D800Y (KMS-;REVEL+) was assessed as benign under the test conditions. However, KMS failed to accurately assess K457E. These combined results reveal the distribution of potentially disease-causing KCNMA1 variants within BK channel functional domains and pathogenicity evaluation for VUS, suggesting strategies for improving channel-level predictions in future studies by building on ensemble algorithms such as KMS.
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8
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Xu M, Zhong XZ, Huang P, Jaślan D, Wang P, Sun X, Weiden EM, EL Hiani Y, Grimm C, Dong XP. TRPML3/BK complex promotes autophagy and bacterial clearance by providing a positive feedback regulation of mTOR via PI3P. Proc Natl Acad Sci U S A 2023; 120:e2215777120. [PMID: 37585464 PMCID: PMC10450854 DOI: 10.1073/pnas.2215777120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 06/22/2023] [Indexed: 08/18/2023] Open
Abstract
TRPML3 is a Ca2+/Na+ release channel residing in both phagophores and endolysosomal membranes. It is activated by PI3P and PI3,5P2. Its activity can be enhanced by high luminal pH and by replacing luminal Na+ with K+. Here, we report that big-conductance Ca2+-activated potassium (BK) channels form a positive feedback loop with TRPML3. Ca2+ release via TRPML3 activates BK, which in turn facilitates TRPML3-mediated Ca2+ release, potentially through removing luminal Na+ inhibition. We further show that TRPML3/BK and mammalian target of rapamycin (mTOR) form another positive feedback loop to facilitate autophagy induction in response to nutrient starvation, i.e., mTOR inhibition upon nutrient starvation activates TRPML3/BK, and this further reduces mTOR activity, thereby increasing autophagy induction. Mechanistically, the feedback regulation between TRPML3/BK and mTOR is mediated by PI3P, an endogenous TRPML3 activator that is enriched in phagophores and is up-regulated by mTOR reduction. Importantly, bacterial infection activates TRPML3 in a BK-dependent manner, and both TRPML3 and BK are required for mTOR suppression and autophagy induction responding to bacterial infection. Suppressing either TRPML3 or BK helps bacteria survival whereas increasing either TRPML3 or BK favors bacterial clearance. Considering that TRPML3/BK is inhibited by low luminal pH but activated by high luminal pH and PI3P in phagophores, we suggest that TRPML3/BK and mTOR form a positive feedback loop via PI3P to ensure efficient autophagy induction in response to nutrient deprivation and bacterial infection. Our study reveals a role of TRPML3-BK coupling in controlling cellular homeostasis and intracellular bacterial clearance via regulating mTOR signaling.
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Affiliation(s)
- Mengnan Xu
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NSB3H 4R2, Canada
| | - Xi Zoë Zhong
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NSB3H 4R2, Canada
| | - Peng Huang
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NSB3H 4R2, Canada
- Chongming Hospital, Shanghai University of Medicine and Health Sciences, Shanghai202150, China
| | - Dawid Jaślan
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich80336, Germany
| | - Pingping Wang
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NSB3H 4R2, Canada
| | - Xue Sun
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NSB3H 4R2, Canada
- Department of Developmental Cell Biology, China Medical University, Shenbei New District, Shenyang110122, China
| | - Eva-Maria Weiden
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich80336, Germany
| | - Yassine EL Hiani
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NSB3H 4R2, Canada
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-Universität, Munich80336, Germany
- Immunology, Infection and Pandemic Research, Fraunhofer Institute for Translational Medicine and Pharmacology, Munich80799, Germany
| | - Xian-Ping Dong
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NSB3H 4R2, Canada
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Ahmed A, Trezza A, Gentile M, Paccagnini E, Panti A, Lupetti P, Spiga O, Bova S, Fusi F. Dynamin-independent Ca V1.2 and K Ca1.1 channels regulation and vascular tone modulation by the mitochondrial fission inhibitors dynasore and dyngo-4a. Eur J Pharmacol 2023; 951:175786. [PMID: 37179045 DOI: 10.1016/j.ejphar.2023.175786] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 05/03/2023] [Accepted: 05/10/2023] [Indexed: 05/15/2023]
Abstract
A role for mitochondrial fission in vascular contraction has been proposed based on the vasorelaxant activity of the dynamin (and mitochondrial fission) inhibitors mdivi-1 and dynasore. However, mdivi-1 is capable to inhibit Ba2+ currents through CaV1.2 channels (IBa1.2), stimulate KCa1.1 channel currents (IKCa1.1), and modulate pathways key to the maintenance of vessel active tone in a dynamin-independent manner. Using a multidisciplinary approach, the present study demonstrates that dynasore, like mdivi-1, is a bi-functional vasodilator, blocking IBa1.2 and stimulating IKCa1.1 in rat tail artery myocytes, as well as promoting relaxation of rat aorta rings pre-contracted by either high K+ or phenylephrine. Conversely, its analogue dyngo-4a, though inhibiting mitochondrial fission triggered by phenylephrine and stimulating IKCa1.1, did not affect IBa1.2 but potentiated both high K+- and phenylephrine-induced contractions. Docking and molecular dynamics simulations identified the molecular basis supporting the different activity of dynasore and dyngo-4a at CaV1.2 and KCa1.1 channels. Mito-tempol only partially counteracted the effects of dynasore and dyngo-4a on phenylephrine-induced tone. In conclusion, the present data, along with previous observations (Ahmed et al., 2022) rise caution for the use of dynasore, mdivi-1, and dyngo-4a as tools to investigate the role of mitochondrial fission in vascular contraction: to this end, a selective dynamin inhibitor and/or a different experimental approach are needed.
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Affiliation(s)
- Amer Ahmed
- Dipartimento di Scienze della Vita, Università di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Alfonso Trezza
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Mariangela Gentile
- Dipartimento di Scienze della Vita, Università di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Eugenio Paccagnini
- Dipartimento di Scienze della Vita, Università di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Alice Panti
- Dipartimento di Scienze della Vita, Università di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Pietro Lupetti
- Dipartimento di Scienze della Vita, Università di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, via A. Moro 2, 53100, Siena, Italy
| | - Sergio Bova
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Fabio Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, via A. Moro 2, 53100, Siena, Italy.
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10
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Gao J, Yin H, Dong Y, Wang X, Liu Y, Wang K. A Novel Role of Uricosuric Agent Benzbromarone in BK Channel Activation and Reduction of Airway Smooth Muscle Contraction. Mol Pharmacol 2023; 103:241-254. [PMID: 36669879 DOI: 10.1124/molpharm.122.000638] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/28/2022] [Accepted: 12/19/2022] [Indexed: 01/21/2023] Open
Abstract
The uricosuric drug benzbromarone, widely used for treatment of gout, hyperpolarizes the membrane potential of airway smooth muscle cells, but how it works remains unknown. Here we show a novel role of benzbromarone in activation of large conductance calcium-activated K+ channels. Benzbromarone results in dose-dependent activation of macroscopic big potassium (BK) currents about 1.7- to 14.5-fold with an EC50 of 111 μM and shifts the voltage-dependent channel activation to a more hyperpolarizing direction about 10 to 54 mV in whole-cell patch clamp recordings. In single-channel recordings, benzbromarone decreases single BKα channel closed dwell time and increases the channel open probability. Coexpressing β1 subunit also enhances BK activation by benzbromarone with an EC50 of 67 μM and a leftward shift of conductance-voltage (G-V) curve about 44 to 138 mV. Site-directed mutagenesis reveals that a motif of three amino acids 329RKK331 in the cytoplasmic linker between S6 and C-terminal regulator of potassium conductance (RCK) gating ring mediates the pharmacological activation of BK channels by benzbromarone. Further ex vivo assay shows that benzbromarone causes reduction of tracheal strip contraction. Taken together, our findings demonstrate that uricosuric benzbromarone activates BK channels through molecular mechanism of action involving the channel RKK motif of S6-RCK linker. Pharmacological activation of BK channel by benzbromarone causes reduction of tracheal strip contraction, holding a repurposing potential for asthma and pulmonary arterial hypertension or BK channelopathies. SIGNIFICANCE STATEMENT: We describe a novel role of uricosuric agent benzbromarone in big potassium (BK) channel activation and relaxation of airway smooth muscle contraction. In this study, we find that benzbromarone is an activator of the large-conductance Ca2+- and voltage-activated K+ channel (BK channel), which serves numerous cellular functions, including control of smooth muscle contraction. Pharmacological activation of BK channel by the FDA-approved drug benzbromarone may hold repurposing potential for treatment of asthma and pulmonary arterial hypertension or BK channelopathies.
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Affiliation(s)
- Jian Gao
- Department of Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing, China (J.G., X.W.); Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (H.Y., Y.D., Y.L., K.W.); and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - Hao Yin
- Department of Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing, China (J.G., X.W.); Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (H.Y., Y.D., Y.L., K.W.); and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - Yanqun Dong
- Department of Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing, China (J.G., X.W.); Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (H.Y., Y.D., Y.L., K.W.); and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - Xintong Wang
- Department of Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing, China (J.G., X.W.); Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (H.Y., Y.D., Y.L., K.W.); and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - Yani Liu
- Department of Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing, China (J.G., X.W.); Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (H.Y., Y.D., Y.L., K.W.); and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
| | - KeWei Wang
- Department of Pharmacology, School of Pharmaceutical Sciences, Peking University, Beijing, China (J.G., X.W.); Department of Pharmacology, School of Pharmacy, Qingdao University Medical College, Qingdao, China (H.Y., Y.D., Y.L., K.W.); and Institute of Innovative Drugs, Qingdao University, Qingdao, China (Y.L., K.W.)
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11
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Ohwada T. 窒素原子を含む結合活性化学種の発見. YAKUGAKU ZASSHI 2023; 143:323-336. [PMID: 37005231 DOI: 10.1248/yakushi.22-00206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
In this review, the authors review and explain their research on "Discovery of Bonding Active Species Containing Nitrogen Atoms" from the past to the present. The authors are interested in new chemical phenomena, especially in the activation of chemical bonds containing nitrogen atoms, and have conducted research to discover chemical bonds with new properties. The activated chemical bonds containing nitrogen atoms are the following (Fig. 1). (1) Rotationally activated C-N bonds by pyramidalization of amide nitrogen atoms (2) N-N bond cleavage ability with reduced bond strength by pyramidalization of nitrosamine nitrogen atoms (3) Transient hetero atom-N bond formation by neighboring group participation of a halogen electron to the nitrogen cation. (4) A unique carbon cation reaction involving nitrogen atoms, especially nitro groups (C-NO2 bond) and ammonium ions (C-NH3+ bond). These purely basic chemistry discoveries unexpectedly led to the creation of functional materials, especially biologically active molecules. We will explain how new chemical bonds led to the creation of new functions.
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Affiliation(s)
- Tomohiko Ohwada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
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12
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Slayden AV, Dyer CL, Ma D, Li W, Bukiya AN, Parrill AL, Dopico AM. Discovery of agonist-antagonist pairs for the modulation of Ca [2]+ and voltage-gated K + channels of large conductance that contain beta1 subunits. Bioorg Med Chem 2022; 68:116876. [PMID: 35716586 PMCID: PMC10464842 DOI: 10.1016/j.bmc.2022.116876] [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: 04/08/2022] [Revised: 05/31/2022] [Accepted: 06/03/2022] [Indexed: 11/02/2022]
Abstract
Large conductance, calcium/voltage-gated potassium channels (BK) regulate critical body processes, including neuronal, secretory and smooth muscle (SM) function. While BK-forming alpha subunits are ubiquitous, accessory beta1 subunits are highly expressed in SM. This makes beta1 an attractive target for pharmaceutical development to treat SM disorders, such as hypertension or cerebrovascular spasm. Compounds activating BK via beta1 have been identified, yet they exhibit low potency and off-target effects while antagonists that limit agonist activity via beta 1 remain unexplored. Beta1-dependent BK ligand-based pharmacophore modeling and ZINC database searches identified 15 commercially available hits. Concentration-response curves on BK alpha + beta1 subunit-mediated currents were obtained in CHO cells. One potent (EC50 = 20 nM) and highly efficacious activator (maximal activation = ×10.3 of control) was identified along with a potent antagonist (KB = 3.02 nM), both of which were dependent on beta1. Our study provides the first proof-of-principle that an agonist/antagonist pair can be used to control beta1-containing BK activity.
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Affiliation(s)
- Alexandria V Slayden
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis TN, 38103, USA
| | - Christy L Dyer
- Department of Chemistry, The University of Memphis, Memphis TN, 38152, USA
| | - Dejian Ma
- Department of Pharmaceutical Sciences, College of Pharmacy, The University of Tennessee Health Science Center, Memphis TN, 38163, USA
| | - Wei Li
- Department of Pharmaceutical Sciences, College of Pharmacy, The University of Tennessee Health Science Center, Memphis TN, 38163, USA
| | - Anna N Bukiya
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis TN, 38103, USA
| | - Abby L Parrill
- Department of Chemistry, The University of Memphis, Memphis TN, 38152, USA
| | - Alex M Dopico
- Department of Pharmacology, Addiction Science and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis TN, 38103, USA.
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13
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Carullo G, Saponara S, Ahmed A, Gorelli B, Mazzotta S, Trezza A, Gianibbi B, Campiani G, Fusi F, Aiello F. Novel Labdane Diterpenes-Based Synthetic Derivatives: Identification of a Bifunctional Vasodilator That Inhibits Ca V1.2 and Stimulates K Ca1.1 Channels. Mar Drugs 2022; 20:md20080515. [PMID: 36005518 PMCID: PMC9410420 DOI: 10.3390/md20080515] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 07/30/2022] [Accepted: 08/11/2022] [Indexed: 11/26/2022] Open
Abstract
Sesquiterpenes such as leucodin and the labdane-type diterpene manool are natural compounds endowed with remarkably in vitro vasorelaxant and in vivo hypotensive activities. Given their structural similarity with the sesquiterpene lactone (+)-sclareolide, this molecule was selected as a scaffold to develop novel vasoactive agents. Functional, electrophysiology, and molecular dynamics studies were performed. The opening of the five-member lactone ring in the (+)-sclareolide provided a series of labdane-based small molecules, promoting a significant in vitro vasorelaxant effect. Electrophysiology data identified 7 as a CaV1.2 channel blocker and a KCa1.1 channel stimulator. These activities were also confirmed in the intact vascular tissue. The significant antagonism caused by the CaV1.2 channel agonist Bay K 8644 suggested that 7 might interact with the dihydropyridine binding site. Docking and molecular dynamic simulations provided the molecular basis of the CaV1.2 channel blockade and KCa1.1 channel stimulation produced by 7. Finally, 7 reduced coronary perfusion pressure and heart rate, while prolonging conduction and refractoriness of the atrioventricular node, likely because of its Ca2+ antagonism. Taken together, these data indicate that the labdane scaffold represents a valuable starting point for the development of new vasorelaxant agents endowed with negative chronotropic properties and targeting key pathways involved in the pathophysiology of hypertension and ischemic cardiomyopathy.
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Affiliation(s)
- Gabriele Carullo
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Simona Saponara
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Amer Ahmed
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Beatrice Gorelli
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Sarah Mazzotta
- Department of Chemistry, University of Milan, Via Golgi 19, 20133 Milano, Italy
| | - Alfonso Trezza
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Beatrice Gianibbi
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Giuseppe Campiani
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Fabio Fusi
- Department of Biotechnology, Chemistry and Pharmacy, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
- Correspondence: (F.F.); (F.A.)
| | - Francesca Aiello
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Edif. Polifunzionale, 87036 Arcavacata di Rende, Italy
- Correspondence: (F.F.); (F.A.)
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14
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Ahmed A, Trezza A, Gentile M, Paccagnini E, Lupetti P, Spiga O, Bova S, Fusi F. The drp-1-mediated mitochondrial fission inhibitor mdivi-1 impacts the function of ion channels and pathways underpinning vascular smooth muscle tone. Biochem Pharmacol 2022; 203:115205. [DOI: 10.1016/j.bcp.2022.115205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/07/2022] [Accepted: 08/02/2022] [Indexed: 11/24/2022]
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15
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Cuong NM, Son NT, Nhan NT, Fukuyama Y, Ahmed A, Saponara S, Trezza A, Gianibbi B, Vigni G, Spiga O, Fusi F. Vietnamese Dalbergia tonkinensis: A Promising Source of Mono- and Bifunctional Vasodilators. Molecules 2022; 27:molecules27144505. [PMID: 35889386 PMCID: PMC9324545 DOI: 10.3390/molecules27144505] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 02/04/2023] Open
Abstract
Hypertension is a risk factor for cardiovascular diseases, which are the main cause of morbidity and mortality in the world. In the search for new molecules capable of targeting KCa1.1 and CaV1.2 channels, the expression of which is altered in hypertension, the in vitro vascular effects of a series of flavonoids extracted from the heartwoods, roots, and leaves of Dalbergia tonkinensis Prain, widely used in traditional medicine, were assessed. Rat aorta rings, tail artery myocytes, and docking and molecular dynamics simulations were used to analyse their effect on these channels. Formononetin, orobol, pinocembrin, and biochanin A showed a marked myorelaxant activity, particularly in rings stimulated by moderate rather than high KCl concentrations. Ba2+ currents through CaV1.2 channels (IBa1.2) were blocked in a concentration-dependent manner by sativanone, 3′-O-methylviolanone, pinocembrin, and biochanin A, while it was stimulated by ambocin. Sativanone, dalsissooside, and eriodictyol inhibited, while tectorigenin 7-O-[β-D-apiofuranosyl-(1→6)-β-D-glucopyranoside], ambocin, butin, and biochanin A increased IKCa1.1. In silico analyses showed that biochanin A, sativanone, and pinocembrin bound with high affinity in target-sensing regions of both channels, providing insight into their potential mechanism of action. In conclusion, Dalbergia tonkinensis is a valuable source of mono- and bifunctional, vasoactive scaffolds for the development of novel antihypertensive drugs.
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Affiliation(s)
- Nguyen Manh Cuong
- Institute of Natural Products Chemistry, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Caugiay, Hanoi 122100, Vietnam
- Correspondence: (N.M.C.); (F.F.)
| | - Ninh The Son
- Institute of Chemistry, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Caugiay, Hanoi 122100, Vietnam;
| | - Ngu Truong Nhan
- Faculty of Science and Technology, Tay Nguyen University, 567 Le Duan, Ea Tam, Buon Ma Thuot 630000, Vietnam;
| | - Yoshiyasu Fukuyama
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima 770-8514, Japan;
| | - Amer Ahmed
- Dipartimento di Scienze della Vita, Università di Siena, Via A. Moro 2, 53100 Siena, Italy; (A.A.); (S.S.)
| | - Simona Saponara
- Dipartimento di Scienze della Vita, Università di Siena, Via A. Moro 2, 53100 Siena, Italy; (A.A.); (S.S.)
| | - Alfonso Trezza
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy; (A.T.); (B.G.); (G.V.); (O.S.)
| | - Beatrice Gianibbi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy; (A.T.); (B.G.); (G.V.); (O.S.)
| | - Ginevra Vigni
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy; (A.T.); (B.G.); (G.V.); (O.S.)
| | - Ottavia Spiga
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy; (A.T.); (B.G.); (G.V.); (O.S.)
| | - Fabio Fusi
- Dipartimento di Biotecnologie, Chimica e Farmacia, Università di Siena, Via A. Moro 2, 53100 Siena, Italy; (A.T.); (B.G.); (G.V.); (O.S.)
- Correspondence: (N.M.C.); (F.F.)
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16
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Zuccolini P, Gavazzo P, Pusch M. BK Channel in the Physiology and in the Cancer of Pancreatic Duct: Impact and Reliability of BK Openers. Front Pharmacol 2022; 13:906608. [PMID: 35685628 PMCID: PMC9171006 DOI: 10.3389/fphar.2022.906608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
BK (KCa 1.1, Slo-1) is a K+ channel characterized by an allosteric regulation of the gating mechanism by Ca2+ binding and voltage, and a high unitary conductance. The channel is expressed in many different tissues, where it is involved in the regulation or the fine-tuning of many physiological processes. Among other organs, BK is expressed in the pancreatic duct, a part of the gland important for the correct ionic composition of the pancreatic juice. Unfortunately, the pancreatic duct is also the site where one of the deadliest cancer types, the pancreatic duct adenocarcinoma (PDAC), develops. In the past years, it has been reported that continuous exposure of cancer cells to BK openers can have a significant impact on cell viability as well as on the ability to proliferate and migrate. Here, we first summarize the main BK channel properties and its roles in pancreatic duct physiology. Then we focus on the potential role of BK as a pharmacological target in PDAC. Moreover, we discuss how results obtained when employing BK activators on cancer cells can, in some cases, be misleading.
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17
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Wrzosek A, Gałecka S, Żochowska M, Olszewska A, Kulawiak B. Alternative Targets for Modulators of Mitochondrial Potassium Channels. Molecules 2022; 27:299. [PMID: 35011530 PMCID: PMC8746388 DOI: 10.3390/molecules27010299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial potassium channels control potassium influx into the mitochondrial matrix and thus regulate mitochondrial membrane potential, volume, respiration, and synthesis of reactive oxygen species (ROS). It has been found that pharmacological activation of mitochondrial potassium channels during ischemia/reperfusion (I/R) injury activates cytoprotective mechanisms resulting in increased cell survival. In cancer cells, the inhibition of these channels leads to increased cell death. Therefore, mitochondrial potassium channels are intriguing targets for the development of new pharmacological strategies. In most cases, however, the substances that modulate the mitochondrial potassium channels have a few alternative targets in the cell. This may result in unexpected or unwanted effects induced by these compounds. In our review, we briefly present the various classes of mitochondrial potassium (mitoK) channels and describe the chemical compounds that modulate their activity. We also describe examples of the multidirectional activity of the activators and inhibitors of mitochondrial potassium channels.
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Affiliation(s)
- Antoni Wrzosek
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Shur Gałecka
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Monika Żochowska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
| | - Anna Olszewska
- Department of Histology, Medical University of Gdansk, 1a Debinki, 80-211 Gdansk, Poland;
| | - Bogusz Kulawiak
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; (A.W.); (S.G.); (M.Ż.)
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18
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Rockman ME, Vouga AG, Rothberg BS. Molecular mechanism of BK channel activation by the smooth muscle relaxant NS11021. J Gen Physiol 2021; 152:151593. [PMID: 32221543 PMCID: PMC7266150 DOI: 10.1085/jgp.201912506] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/12/2020] [Indexed: 12/31/2022] Open
Abstract
Large-conductance Ca2+-activated K+ channels (BK channels) are activated by cytosolic calcium and depolarized membrane potential under physiological conditions. Thus, these channels control electrical excitability in neurons and smooth muscle by gating K+ efflux and hyperpolarizing the membrane in response to Ca2+ signaling. Altered BK channel function has been linked to epilepsy, dyskinesia, and other neurological deficits in humans, making these channels a key target for drug therapies. To gain insight into mechanisms underlying pharmacological modulation of BK channel gating, here we studied mechanisms underlying activation of BK channels by the biarylthiourea derivative, NS11021, which acts as a smooth muscle relaxant. We observe that increasing NS11021 shifts the half-maximal activation voltage for BK channels toward more hyperpolarized voltages, in both the presence and nominal absence of Ca2+, suggesting that NS11021 facilitates BK channel activation primarily by a mechanism that is distinct from Ca2+ activation. 30 µM NS11021 slows the time course of BK channel deactivation at −200 mV by ∼10-fold compared with 0 µM NS11021, while having little effect on the time course of activation. This action is most pronounced at negative voltages, at which the BK channel voltage sensors are at rest. Single-channel kinetic analysis further shows that 30 µM NS11021 increases open probability by 62-fold and increases mean open time from 0.15 to 0.52 ms in the nominal absence of Ca2+ at voltages less than −60 mV, conditions in which BK voltage sensors are largely in the resting state. We could therefore account for the major activating effects of NS11021 by a scheme in which the drug primarily shifts the pore-gate equilibrium toward the open state.
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Affiliation(s)
- Michael E Rockman
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
| | - Alexandre G Vouga
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
| | - Brad S Rothberg
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
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19
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Vouga AG, Rockman ME, Yan J, Jacobson MA, Rothberg BS. State-dependent inhibition of BK channels by the opioid agonist loperamide. J Gen Physiol 2021; 153:212539. [PMID: 34357374 PMCID: PMC8352719 DOI: 10.1085/jgp.202012834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 04/19/2021] [Accepted: 07/08/2021] [Indexed: 12/20/2022] Open
Abstract
Large-conductance Ca2+-activated K+ (BK) channels control a range of physiological functions, and their dysfunction is linked to human disease. We have found that the widely used drug loperamide (LOP) can inhibit activity of BK channels composed of either α-subunits (BKα channels) or α-subunits plus the auxiliary γ1-subunit (BKα/γ1 channels), and here we analyze the molecular mechanism of LOP action. LOP applied at the cytosolic side of the membrane rapidly and reversibly inhibited BK current, an effect that appeared as a decay in voltage-activated BK currents. The apparent affinity for LOP decreased with hyperpolarization in a manner consistent with LOP behaving as an inhibitor of open, activated channels. Increasing LOP concentration reduced the half-maximal activation voltage, consistent with relative stabilization of the LOP-inhibited open state. Single-channel recordings revealed that LOP did not reduce unitary BK channel current, but instead decreased BK channel open probability and mean open times. LOP elicited use-dependent inhibition, in which trains of brief depolarizing steps lead to accumulated reduction of BK current, whereas single brief depolarizing steps do not. The principal effects of LOP on BK channel gating are described by a mechanism in which LOP acts as a state-dependent pore blocker. Our results suggest that therapeutic doses of LOP may act in part by inhibiting K+ efflux through intestinal BK channels.
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Affiliation(s)
- Alexandre G Vouga
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
| | - Michael E Rockman
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX
| | - Marlene A Jacobson
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia PA
| | - Brad S Rothberg
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA
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20
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2-Hydroxy-5-(3,5,7-trihydroxy-4-oxo-4H-chromen-2-yl)phenyl (E)-3-(4-hydroxy-3-methoxyphenyl)acrylate: Synthesis, In Silico Analysis and In Vitro Pharmacological Evaluation. MOLBANK 2021. [DOI: 10.3390/m1258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Quercetin and ferulic acid are two phytochemicals extensively represented in the plant kingdom and daily consumed in considerable amounts through diets. Due to a common phenolic structure, these two molecules share several pharmacological properties, e.g., antioxidant and free radical scavenging, anti-cancer, anti-inflammatory, anti-arrhythmic, and vasorelaxant. The aim of the present work was the combination of the two molecules in a single chemical entity, conceivably endowed with more efficacious vasorelaxant activity. Preliminary in silico studies herein described suggested that the new hybrid compound bound spontaneously and with high affinity on the KCa1.1 channel. Thus, the synthesis of the 3′-ferulic ester derivative of quercetin was achieved and its structure confirmed by 1H- and 13C-NMR spectra, HSQC and HMBC experiments, mass spectrometry, and elementary analysis. The effect of the new hybrid compound on vascular KCa1.1 and CaV1.2 channels revealed a partial loss of the stimulatory activity that characterizes the parent compound quercetin. Therefore, further studies are necessary to identify a better strategy to improve the vascular properties of this flavonoid.
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21
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A multitarget semi-synthetic derivative of the flavonoid morin with improved in vitro vasorelaxant activity: Role of Ca V1.2 and K Ca1.1 channels. Biochem Pharmacol 2021; 185:114429. [PMID: 33513341 DOI: 10.1016/j.bcp.2021.114429] [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] [Received: 10/09/2020] [Revised: 12/28/2020] [Accepted: 01/19/2021] [Indexed: 12/24/2022]
Abstract
CaV1.2 channels play a fundamental role in the regulation of vascular smooth muscle tone. The aim of the present study was to synthesize morin derivatives bearing the nitrophenyl moiety of dihydropyridine Ca2+ antagonists to increase the flavonoid vasorelaxant activity. The effects of morin and its derivatives were assessed on CaV1.2 and KCa1.1 channels, both in vitro and in silico, as well as on the contractile responses of rat aorta rings. All compounds were effective CaV1.2 channel blockers, positioning in the α1C subunit region where standard blockers bind. Among the four newly synthesized morin derivatives, the penta-acetylated morin-1 was the most efficacious Ca2+ antagonist, presenting a vasorelaxant profile superior to that of the parent compound and, contrary to morin, antagonized also the release of Ca2+ from the sarcoplasmic reticulum; surprisingly, it also stimulated KCa1.1 channel current. Computational analysis demonstrated that morin-1 bound close to the KCa1.1 channel S6 segment. In conclusion, these findings open a new avenue for the synthesis of valuable multi-functional, vasorelaxant morin derivatives capable to target several pathways underpinning the pathogenesis of hypertension.
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22
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Martín P, Moncada M, Castillo K, Orsi F, Ducca G, Fernández-Fernández JM, González C, Milesi V. Arachidonic acid effect on the allosteric gating mechanism of BK (Slo1) channels associated with the β1 subunit. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183550. [PMID: 33417967 DOI: 10.1016/j.bbamem.2021.183550] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/04/2020] [Accepted: 12/30/2020] [Indexed: 11/30/2022]
Abstract
Arachidonic acid (AA) is a fatty acid involved in the modulation of several ion channels. Previously, we reported that AA activates the high conductance Ca2+- and voltage-dependent K+ channel (BK) in vascular smooth muscle depending on the expression of the auxiliary β1 subunit. Here, using the patch-clamp technique on BK channel co-expressed with β1 subunit in a heterologous cell expression system, we analyzed whether AA modifies the three functional modules involved in the channel gating: the voltage sensor domain (VSD), the pore domain (PD), and the intracellular calcium sensor domain (CSD). We present evidence that AA activates BK channel in a direct way, inducing VSD stabilization on its active configuration observed as a significant left shift in the Q-V curve obtained from gating currents recordings. Moreover, AA facilitates the channel opening transitions when VSD are at rest, and the CSD are unoccupied. Furthermore, the activation was independent of the intracellular Ca2+ concentration and reduced when the BK channel was co-expressed with the Y74A mutant of the β1 subunit. These results allow us to present new insigths in the mechanism by which AA modulates BK channels co-expressed with its auxiliary β1 subunit.
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Affiliation(s)
- Pedro Martín
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina.
| | - Melisa Moncada
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina.
| | - Karen Castillo
- CINV: Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
| | - Federico Orsi
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina.
| | - Gerónimo Ducca
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina.
| | - José Manuel Fernández-Fernández
- Laboratory of Molecular Physiology, Department of Experimental and Health Sciences, University Pompeu Fabra, 08003 Barcelona, Spain.
| | - Carlos González
- CINV: Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
| | - Verónica Milesi
- Instituto de Estudios Inmunológicos y Fisiopatológicos (IIFP), UNLP, CONICET, asociado CIC PBA, Facultad de Ciencias Exactas, La Plata, Argentina.
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23
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Abstract
Rockman et al. in this issue of JGP describe how NS11021 opens BK channels, which make the compound a better tool to probe physiological roles and gating mechanisms of BK channels.
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Affiliation(s)
- Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO
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24
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Carullo G, Ahmed A, Trezza A, Spiga O, Brizzi A, Saponara S, Fusi F, Aiello F. Design, synthesis and pharmacological evaluation of ester-based quercetin derivatives as selective vascular K Ca1.1 channel stimulators. Bioorg Chem 2020; 105:104404. [PMID: 33142229 DOI: 10.1016/j.bioorg.2020.104404] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/08/2020] [Accepted: 10/19/2020] [Indexed: 12/27/2022]
Abstract
Quercetin represents one of the most studied dietary flavonoids; it exerts a panel of pharmacological activities particularly on the cardiovascular system. Stimulation of vascular KCa1.1 channels contributes to its vasorelaxant activity, which is, however, counteracted in part by its concomitant stimulation of CaV1.2 channels. Therefore, several quercetin hybrid derivatives were designed and synthesized to produce a more selective KCa1.1 channel stimulator, then assessed both in silico and in vitro. All the derivatives interacted with the KCa1.1 channel with similar binding energy values. Among the selected derivatives, 1E was a weak vasodilator, though displaying an interesting CaV1.2 channel blocking activity. The lipoyl derivatives 1F and 3F, though showing pharmacological and electrophysiological features similar to those of quercetin, seemed to be more effective as KCa1.1 channel stimulators as compared to the parent compound. The strategy pursued demonstrated how different chemical substituents on the quercetin core can change/invert its effect on CaV1.2 channels or enhance its KCa1.1 channel stimulatory activity, thus opening new avenues for the synthesis of efficacious vasorelaxant quercetin hybrids.
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Affiliation(s)
- Gabriele Carullo
- Department of Pharmacy, Health and Nutritional Sciences, DoE 2018-2022, University of Calabria, Edificio Polifunzionale, 87036 Rende (CS), Italy; Department of Biotechnology, Chemistry and Pharmacy, DoE 2018-2022, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Amer Ahmed
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Alfonso Trezza
- Department of Biotechnology, Chemistry and Pharmacy, DoE 2018-2022, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Ottavia Spiga
- Department of Biotechnology, Chemistry and Pharmacy, DoE 2018-2022, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Antonella Brizzi
- Department of Biotechnology, Chemistry and Pharmacy, DoE 2018-2022, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
| | - Simona Saponara
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy.
| | - Fabio Fusi
- Department of Biotechnology, Chemistry and Pharmacy, DoE 2018-2022, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy.
| | - Francesca Aiello
- Department of Pharmacy, Health and Nutritional Sciences, DoE 2018-2022, University of Calabria, Edificio Polifunzionale, 87036 Rende (CS), Italy
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25
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Yazdani M, Zhang G, Jia Z, Shi J, Cui J, Chen J. Aromatic interactions with membrane modulate human BK channel activation. eLife 2020; 9:55571. [PMID: 32597752 PMCID: PMC7371421 DOI: 10.7554/elife.55571] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/28/2020] [Indexed: 12/22/2022] Open
Abstract
Large-conductance potassium (BK) channels are transmembrane (TM) proteins that can be synergistically and independently activated by membrane voltage and intracellular Ca2+. The only covalent connection between the cytosolic Ca2+ sensing domain and the TM pore and voltage sensing domains is a 15-residue ‘C-linker’. To determine the linker’s role in human BK activation, we designed a series of linker sequence scrambling mutants to suppress potential complex interplay of specific interactions with the rest of the protein. The results revealed a surprising sensitivity of BK activation to the linker sequence. Combining atomistic simulations and further mutagenesis experiments, we demonstrated that nonspecific interactions of the linker with membrane alone could directly modulate BK activation. The C-linker thus plays more direct roles in mediating allosteric coupling between BK domains than previously assumed. Our results suggest that covalent linkers could directly modulate TM protein function and should be considered an integral component of the sensing apparatus.
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Affiliation(s)
- Mahdieh Yazdani
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | - Guohui Zhang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St Louis, United States
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, United States
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St Louis, United States
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St Louis, United States
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, United States.,Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, United States
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26
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Reed JT, Pareek T, Sriramula S, Pabbidi MR. Aging influences cerebrovascular myogenic reactivity and BK channel function in a sex-specific manner. Cardiovasc Res 2020; 116:1372-1385. [PMID: 31738403 DOI: 10.1093/cvr/cvz314] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/06/2019] [Accepted: 11/15/2019] [Indexed: 11/14/2022] Open
Abstract
AIMS The myogenic reactivity of the middle cerebral arteries (MCA) protects the brain by altering the diameter in response to changes in lumen pressure. Large conductance potassium (BK) channels are known to regulate the myogenic reactivity, yet, it is not clear how aging alters the myogenic reactivity via the BK channel in males and females. Thus, we hypothesize that age-associated changes in BK channel subunits modulate the myogenic reactivity in a sex-specific manner. METHODS AND RESULTS We used vascular reactivity, patch-clamp, and biochemical methods to measure myogenic reactivity, BK channel function, and expression, respectively in cerebral vessels of adult and aged male and female Sprague Dawley rats. Our results suggest that aging and ovariectomy (OVX) exaggerated the myogenic reactivity of MCA in females but attenuated it in males. Aging induced outward eutrophic remodelling in females but inward hypertrophic remodelling in males. Aging decreased total, Kv, BK channel currents, and spontaneous transient outward currents (STOC) in vascular smooth muscle cells isolated from females, but not in males. Aging increased BKα subunit mRNA and protein both in males and females. However, aging decreased BKβ1 subunit protein and mRNA in females only. In males, BKβ1 mRNA is increased, but protein is decreased. Iberiotoxin-induced MCA constriction is lower in aged females but higher in aged males. Activation of BKα (10 µM NS1619) and BKβ1 (10 µM S-Equol) subunits failed to increase STOCs and were unable to decrease the myogenic reactivity of MCA in aged female but not in aged male rats. OVX decreased, but chronic supplementation of oestradiol restored BK channel expression and function. CONCLUSION Overall our results suggest that aging or OVX-associated downregulation of the BKβ1 expression and function in females results in exaggerated myogenic reactivity of MCA. However, age-associated increase in BK channel function in males attenuated myogenic reactivity of MCA.
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Affiliation(s)
- Joseph T Reed
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA
| | - Tanya Pareek
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA
| | - Srinivas Sriramula
- Department of Pharmacology and Toxicology, Brody School of Medicine at East Carolina University, 600 Moye Blvd, Greenville, NC 27834-4300, USA
| | - Mallikarjuna R Pabbidi
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216-4505, USA
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27
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Haidar O, O'Neill N, Staunton CA, Bavan S, O'Brien F, Zouggari S, Sharif U, Mobasheri A, Kumagai K, Barrett-Jolley R. Pro-inflammatory Cytokines Drive Deregulation of Potassium Channel Expression in Primary Synovial Fibroblasts. Front Physiol 2020; 11:226. [PMID: 32265733 PMCID: PMC7105747 DOI: 10.3389/fphys.2020.00226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 02/27/2020] [Indexed: 01/15/2023] Open
Abstract
The synovium secretes synovial fluid, but is also richly innervated with nociceptors and acts as a gateway between avascular joint tissues and the circulatory system. Resident fibroblast-like synoviocytes' (FLS) calcium-activated potassium channels (K Ca) change in activity in arthritis models and this correlates with FLS activation. Objective To investigate this activation in an in vitro model of inflammatory arthritis; 72 h treatment with cytokines TNFα and IL1β. Methods FLS cells were isolated from rat synovial membranes. We analyzed global changes in FLS mRNA by RNA-sequencing, then focused on FLS ion channel genes and the corresponding FLS electrophysiological phenotype and finally modeling data with ingenuity pathway analysis (IPA) and MATLAB. Results IPA showed significant activation of inflammatory, osteoarthritic and calcium signaling canonical pathways by cytokines, and we identified ∼200 channel gene transcripts. The large K Ca (BK) channel consists of the pore forming Kcnma1 together with β-subunits. Following cytokine treatment, a significant increase in Kcnma1 RNA abundance was detected by qPCR and changes in several ion channels were detected by RNA-sequencing, including a loss of BK channel β-subunit expression Kcnmb1/2 and an increase in Kcnmb3. In electrophysiological experiments, there was a decrease in over-all current density at 20 mV without change in chord conductance at this potential. Conclusion TNFα and IL1β treatment of FLS in vitro recapitulated several common features of inflammatory arthritis at the transcriptomic level, including increase in Kcnma1 and Kcnmb3 gene expression.
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Affiliation(s)
- Omar Haidar
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Nathanael O'Neill
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Caroline A Staunton
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Selvan Bavan
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Fiona O'Brien
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Sarah Zouggari
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Umar Sharif
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom
| | - Ali Mobasheri
- Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland.,Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, Vilnius, Lithuania.,Department of Orthopedics and Department of Rheumatology & Clinical Immunology, UMC Utrecht, Utrecht, Netherlands.,Versus Arthritis Centre for Sport, Exercise and Osteoarthritis Research, Queen's Medical Centre, Nottingham, United Kingdom
| | - Kosuke Kumagai
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom.,Department of Orthopaedic Surgery, Shiga University of Medical Science, Shiga, Japan
| | - Richard Barrett-Jolley
- Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom.,Versus Arthritis Centre for Sport, Exercise and Osteoarthritis Research, Queen's Medical Centre, Nottingham, United Kingdom
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28
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Loss-of-function BK channel mutation causes impaired mitochondria and progressive cerebellar ataxia. Proc Natl Acad Sci U S A 2020; 117:6023-6034. [PMID: 32132200 DOI: 10.1073/pnas.1920008117] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Despite a growing number of ion channel genes implicated in hereditary ataxia, it remains unclear how ion channel mutations lead to loss-of-function or death of cerebellar neurons. Mutations in the gene KCNMA1, encoding the α-subunit of the BK channel have emerged as responsible for a variety of neurological phenotypes. We describe a mutation (BKG354S) in KCNMA1, in a child with congenital and progressive cerebellar ataxia with cognitive impairment. The mutation in the BK channel selectivity filter dramatically reduced single-channel conductance and ion selectivity. The BKG354S channel trafficked normally to plasma, nuclear, and mitochondrial membranes, but caused reduced neurite outgrowth, cell viability, and mitochondrial content. Small interfering RNA (siRNA) knockdown of endogenous BK channels had similar effects. The BK activator, NS1619, rescued BKG354S cells but not siRNA-treated cells, by selectively blocking the mutant channels. When expressed in cerebellum via adenoassociated virus (AAV) viral transfection in mice, the mutant BKG354S channel, but not the BKWT channel, caused progressive impairment of several gait parameters consistent with cerebellar dysfunction from 40- to 80-d-old mice. Finally, treatment of the patient with chlorzoxazone, a BK/SK channel activator, partially improved motor function, but ataxia continued to progress. These studies indicate that a loss-of-function BK channel mutation causes ataxia and acts by reducing mitochondrial and subsequently cellular viability.
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29
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Bailey CS, Moldenhauer HJ, Park SM, Keros S, Meredith AL. KCNMA1-linked channelopathy. J Gen Physiol 2019; 151:1173-1189. [PMID: 31427379 PMCID: PMC6785733 DOI: 10.1085/jgp.201912457] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 08/13/2019] [Indexed: 12/20/2022] Open
Abstract
Bailey et al. review a new neurological channelopathy associated with KCNMA1, encoding the BK voltage- and Ca2+-activated K+ channel. KCNMA1 encodes the pore-forming α subunit of the “Big K+” (BK) large conductance calcium and voltage-activated K+ channel. BK channels are widely distributed across tissues, including both excitable and nonexcitable cells. Expression levels are highest in brain and muscle, where BK channels are critical regulators of neuronal excitability and muscle contractility. A global deletion in mouse (KCNMA1−/−) is viable but exhibits pathophysiology in many organ systems. Yet despite the important roles in animal models, the consequences of dysfunctional BK channels in humans are not well characterized. Here, we summarize 16 rare KCNMA1 mutations identified in 37 patients dating back to 2005, with an array of clinically defined pathological phenotypes collectively referred to as “KCNMA1-linked channelopathy.” These mutations encompass gain-of-function (GOF) and loss-of-function (LOF) alterations in BK channel activity, as well as several variants of unknown significance (VUS). Human KCNMA1 mutations are primarily associated with neurological conditions, including seizures, movement disorders, developmental delay, and intellectual disability. Due to the recent identification of additional patients, the spectrum of symptoms associated with KCNMA1 mutations has expanded but remains primarily defined by brain and muscle dysfunction. Emerging evidence suggests the functional BK channel alterations produced by different KCNMA1 alleles may associate with semi-distinct patient symptoms, such as paroxysmal nonkinesigenic dyskinesia (PNKD) with GOF and ataxia with LOF. However, due to the de novo origins for the majority of KCNMA1 mutations identified to date and the phenotypic variability exhibited by patients, additional evidence is required to establish causality in most cases. The symptomatic picture developing from patients with KCNMA1-linked channelopathy highlights the importance of better understanding the roles BK channels play in regulating cell excitability. Establishing causality between KCNMA1-linked BK channel dysfunction and specific patient symptoms may reveal new treatment approaches with the potential to increase therapeutic efficacy over current standard regimens.
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Affiliation(s)
- Cole S Bailey
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Hans J Moldenhauer
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Su Mi Park
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Sotirios Keros
- Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, SD
| | - Andrea L Meredith
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
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30
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Large-conductance Ca 2+- and voltage-gated K + channels form and break interactions with membrane lipids during each gating cycle. Proc Natl Acad Sci U S A 2019; 116:8591-8596. [PMID: 30967508 DOI: 10.1073/pnas.1901381116] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Membrane depolarization and intracellular Ca2+ promote activation of the large-conductance Ca2+- and voltage-gated (Slo1) big potassium (BK) channel. We examined the physical interactions that stabilize the closed and open conformations of the ion conduction gate of the human Slo1 channel using electrophysiological and computational approaches. The results show that the closed conformation is stabilized by intersubunit ion-ion interactions involving negative residues (E321 and E324) and positive residues (329RKK331) at the cytoplasmic ends of the transmembrane S6 segments ("RKK ring"). When the channel gate is open, the RKK ring is broken and the positive residues instead make electrostatic interactions with nearby membrane lipid oxygen atoms. E321 and E324 are stabilized by water. When the 329RKK331 residues are mutated to hydrophobic amino acids, these residues form even stronger hydrophobic interactions with the lipid tails to promote the open conformation, shifting the voltage dependence of activation to the negative direction by up to 400 mV and stabilizing the selectivity filter region. Thus, the RKK segment forms electrostatic interactions with oxygen atoms from two sources, other amino acid residues (E321/E324), and membrane lipids, depending on the gate status. Each time the channel opens and closes, the aforementioned interactions are formed and broken. This lipid-dependent Slo1 gating may explain how amphipathic signaling molecules and pharmacologically active agents influence the channel activity, and a similar mechanism may be operative in other ion channels.
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31
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Gessner G, Sahoo N, Swain SM, Hirth G, Schönherr R, Mede R, Westerhausen M, Brewitz HH, Heimer P, Imhof D, Hoshi T, Heinemann SH. CO-independent modification of K + channels by tricarbonyldichlororuthenium(II) dimer (CORM-2). Eur J Pharmacol 2017; 815:33-41. [PMID: 28987271 DOI: 10.1016/j.ejphar.2017.10.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/26/2017] [Accepted: 10/04/2017] [Indexed: 12/11/2022]
Abstract
Although toxic when inhaled in high concentrations, the gas carbon monoxide (CO) is endogenously produced in mammals, and various beneficial effects are reported. For potential medicinal applications and studying the molecular processes underlying the pharmacological action of CO, so-called CO-releasing molecules (CORMs), such as tricabonyldichlororuthenium(II) dimer (CORM-2), have been developed and widely used. Yet, it is not readily discriminated whether an observed effect of a CORM is caused by the released CO gas, the CORM itself, or any of its intermediate or final breakdown products. Focusing on Ca2+- and voltage-dependent K+ channels (KCa1.1) and voltage-gated K+ channels (Kv1.5, Kv11.1) relevant for cardiac safety pharmacology, we demonstrate that, in most cases, the functional impacts of CORM-2 on these channels are not mediated by CO. Instead, when dissolved in aqueous solutions, CORM-2 has the propensity of forming Ru(CO)2 adducts, preferentially to histidine residues, as demonstrated with synthetic peptides using mass-spectrometry analysis. For KCa1.1 channels we show that H365 and H394 in the cytosolic gating ring structure are affected by CORM-2. For Kv11.1 channels (hERG1) the extracellularly accessible histidines H578 and H587 are CORM-2 targets. The strong CO-independent action of CORM-2 on Kv11.1 and Kv1.5 channels can be completely abolished when CORM-2 is applied in the presence of an excess of free histidine or human serum albumin; cysteine and methionine are further potential targets. Off-site effects similar to those reported here for CORM-2 are found for CORM-3, another ruthenium-based CORM, but are diminished when using iron-based CORM-S1 and absent for manganese-based CORM-EDE1.
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Affiliation(s)
- Guido Gessner
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena & Jena University Hospital, Hans-Knöll-Str. 2, D-07745 Jena, Germany
| | - Nirakar Sahoo
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena & Jena University Hospital, Hans-Knöll-Str. 2, D-07745 Jena, Germany
| | - Sandip M Swain
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena & Jena University Hospital, Hans-Knöll-Str. 2, D-07745 Jena, Germany
| | - Gianna Hirth
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena & Jena University Hospital, Hans-Knöll-Str. 2, D-07745 Jena, Germany
| | - Roland Schönherr
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena & Jena University Hospital, Hans-Knöll-Str. 2, D-07745 Jena, Germany
| | - Ralf Mede
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Jena, Germany
| | - Matthias Westerhausen
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Jena, Germany
| | - Hans Henning Brewitz
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Pascal Heimer
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Diana Imhof
- Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, Bonn, Germany
| | - Toshinori Hoshi
- Department of Physiology, University of Pennsylvania, Philadelphia, USA
| | - Stefan H Heinemann
- Center for Molecular Biomedicine, Department of Biophysics, Friedrich Schiller University Jena & Jena University Hospital, Hans-Knöll-Str. 2, D-07745 Jena, Germany.
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32
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Baker D, Pryce G, Visintin C, Sisay S, Bondarenko AI, Vanessa Ho WS, Jackson SJ, Williams TE, Al-Izki S, Sevastou I, Okuyama M, Graier WF, Stevenson LA, Tanner C, Ross R, Pertwee RG, Henstridge CM, Irving AJ, Schulman J, Powell K, Baker MD, Giovannoni G, Selwood DL. Big conductance calcium-activated potassium channel openers control spasticity without sedation. Br J Pharmacol 2017; 174:2662-2681. [PMID: 28677901 PMCID: PMC5522996 DOI: 10.1111/bph.13889] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/27/2017] [Accepted: 05/17/2017] [Indexed: 12/19/2022] Open
Abstract
Background and Purpose Our initial aim was to generate cannabinoid agents that control spasticity, occurring as a consequence of multiple sclerosis (MS), whilst avoiding the sedative side effects associated with cannabis. VSN16R was synthesized as an anandamide (endocannabinoid) analogue in an anti‐metabolite approach to identify drugs that target spasticity. Experimental Approach Following the initial chemistry, a variety of biochemical, pharmacological and electrophysiological approaches, using isolated cells, tissue‐based assays and in vivo animal models, were used to demonstrate the activity, efficacy, pharmacokinetics and mechanism of action of VSN16R. Toxicological and safety studies were performed in animals and humans. Key Results VSN16R had nanomolar activity in tissue‐based, functional assays and dose‐dependently inhibited spasticity in a mouse experimental encephalomyelitis model of MS. This effect occurred with over 1000‐fold therapeutic window, without affecting normal muscle tone. Efficacy was achieved at plasma levels that are feasible and safe in humans. VSN16R did not bind to known CB1/CB2/GPPR55 cannabinoid‐related receptors in receptor‐based assays but acted on a vascular cannabinoid target. This was identified as the major neuronal form of the big conductance, calcium‐activated potassium (BKCa) channel. Drug‐induced opening of neuronal BKCa channels induced membrane hyperpolarization, limiting excessive neural‐excitability and controlling spasticity. Conclusions and Implications We identified the neuronal form of the BKCa channel as the target for VSN16R and demonstrated that its activation alleviates neuronal excitability and spasticity in an experimental model of MS, revealing a novel mechanism to control spasticity. VSN16R is a potential, safe and selective ligand for controlling neural hyper‐excitability in spasticity.
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Affiliation(s)
- David Baker
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.,Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, UK
| | - Gareth Pryce
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.,Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, UK
| | - Cristina Visintin
- Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, UK.,Department of Medicinal Chemistry, UCL Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Sofia Sisay
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Alexander I Bondarenko
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.,A.A. Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - W S Vanessa Ho
- Vascular Biology Research Centre. St. George's, University of London, London, UK
| | - Samuel J Jackson
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Thomas E Williams
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Sarah Al-Izki
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Ioanna Sevastou
- Department of Medicinal Chemistry, UCL Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Masahiro Okuyama
- Department of Medicinal Chemistry, UCL Wolfson Institute for Biomedical Research, University College London, London, UK
| | - Wolfgang F Graier
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Lesley A Stevenson
- Vascular Biology Research Centre. St. George's, University of London, London, UK
| | - Carolyn Tanner
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Ruth Ross
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Roger G Pertwee
- Department of Biomedical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Christopher M Henstridge
- Neurosciences Institute, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Andrew J Irving
- Neurosciences Institute, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Jesse Schulman
- Canbex Therapeutics Ltd, London BioScience Innovation Centre, London, UK
| | - Keith Powell
- Canbex Therapeutics Ltd, London BioScience Innovation Centre, London, UK
| | - Mark D Baker
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gavin Giovannoni
- Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.,Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, UK
| | - David L Selwood
- Department of Medicinal Chemistry, UCL Wolfson Institute for Biomedical Research, University College London, London, UK
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A New Synthetic Route Towards Picealactone a from an Abietic Acid. Chem Nat Compd 2017. [DOI: 10.1007/s10600-017-2084-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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The Slo(w) path to identifying the mitochondrial channels responsible for ischemic protection. Biochem J 2017; 474:2067-2094. [PMID: 28600454 DOI: 10.1042/bcj20160623] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/10/2017] [Accepted: 02/13/2017] [Indexed: 12/19/2022]
Abstract
Mitochondria play an important role in tissue ischemia and reperfusion (IR) injury, with energetic failure and the opening of the mitochondrial permeability transition pore being the major causes of IR-induced cell death. Thus, mitochondria are an appropriate focus for strategies to protect against IR injury. Two widely studied paradigms of IR protection, particularly in the field of cardiac IR, are ischemic preconditioning (IPC) and volatile anesthetic preconditioning (APC). While the molecular mechanisms recruited by these protective paradigms are not fully elucidated, a commonality is the involvement of mitochondrial K+ channel opening. In the case of IPC, research has focused on a mitochondrial ATP-sensitive K+ channel (mitoKATP), but, despite recent progress, the molecular identity of this channel remains a subject of contention. In the case of APC, early research suggested the existence of a mitochondrial large-conductance K+ (BK, big conductance of potassium) channel encoded by the Kcnma1 gene, although more recent work has shown that the channel that underlies APC is in fact encoded by Kcnt2 In this review, we discuss both the pharmacologic and genetic evidence for the existence and identity of mitochondrial K+ channels, and the role of these channels both in IR protection and in regulating normal mitochondrial function.
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Latorre R, Castillo K, Carrasquel-Ursulaez W, Sepulveda RV, Gonzalez-Nilo F, Gonzalez C, Alvarez O. Molecular Determinants of BK Channel Functional Diversity and Functioning. Physiol Rev 2017; 97:39-87. [DOI: 10.1152/physrev.00001.2016] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Large-conductance Ca2+- and voltage-activated K+ (BK) channels play many physiological roles ranging from the maintenance of smooth muscle tone to hearing and neurosecretion. BK channels are tetramers in which the pore-forming α subunit is coded by a single gene ( Slowpoke, KCNMA1). In this review, we first highlight the physiological importance of this ubiquitous channel, emphasizing the role that BK channels play in different channelopathies. We next discuss the modular nature of BK channel-forming protein, in which the different modules (the voltage sensor and the Ca2+ binding sites) communicate with the pore gates allosterically. In this regard, we review in detail the allosteric models proposed to explain channel activation and how the models are related to channel structure. Considering their extremely large conductance and unique selectivity to K+, we also offer an account of how these two apparently paradoxical characteristics can be understood consistently in unison, and what we have learned about the conduction system and the activation gates using ions, blockers, and toxins. Attention is paid here to the molecular nature of the voltage sensor and the Ca2+ binding sites that are located in a gating ring of known crystal structure and constituted by four COOH termini. Despite the fact that BK channels are coded by a single gene, diversity is obtained by means of alternative splicing and modulatory β and γ subunits. We finish this review by describing how the association of the α subunit with β or with γ subunits can change the BK channel phenotype and pharmacology.
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Affiliation(s)
- Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Willy Carrasquel-Ursulaez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Romina V. Sepulveda
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Fernando Gonzalez-Nilo
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Carlos Gonzalez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Osvaldo Alvarez
- Centro Interdisciplinario de Neurociencia de Valparaíso and Doctorado en Ciencias Mención Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile; Universidad Andres Bello, Facultad de Ciencias Biologicas, Center for Bioinformatics and Integrative Biology, Avenida Republica 239, Santiago, Chile and Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
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Yan Z, Hu B, Huang Z, Zhong L, Guo X, Weng A, Xiao F, Zeng W, Zhang Y, Ding J, Hou P. Single Channel Recordings Reveal Differential β2 Subunit Modulations Between Mammalian and Drosophila BKCa(β2) Channels. PLoS One 2016; 11:e0163308. [PMID: 27755549 PMCID: PMC5068790 DOI: 10.1371/journal.pone.0163308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 09/07/2016] [Indexed: 12/23/2022] Open
Abstract
Large-conductance Ca2+- and voltage-activated potassium (BK) channels are widely expressed in tissues. As a voltage and calcium sensor, BK channels play significant roles in regulating the action potential frequency, neurotransmitter release, and smooth muscle contraction. After associating with the auxiliary β2 subunit, mammalian BK(β2) channels (mouse or human Slo1/β2) exhibit enhanced activation and complete inactivation. However, how the β2 subunit modulates the Drosophila Slo1 channel remains elusive. In this study, by comparing the different functional effects on heterogeneous BK(β2) channel, we found that Drosophila Slo1/β2 channel exhibits “paralyzed”-like and incomplete inactivation as well as slow activation. Further, we determined three different modulations between mammalian and Drosophila BK(β2) channels: 1) dSlo1/β2 doesn’t have complete inactivation. 2) β2(K33,R34,K35) delays the dSlo1/Δ3-β2 channel activation. 3) dSlo1/β2 channel has enhanced pre-inactivation than mSlo1/β2 channel. The results in our study provide insights into the different modulations of β2 subunit between mammalian and Drosophila Slo1/β2 channels and structural basis underlie the activation and pre-inactivation of other BK(β) complexes.
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Affiliation(s)
- Zhenzhen Yan
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Bin Hu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Zhigang Huang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Ling Zhong
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, 63130, United States
| | - Xiying Guo
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Anxi Weng
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Feng Xiao
- Key Laboratory of Image Processing and Intelligent Control, Huazhong University of Science and Technology, Ministry of Education, Department of Biomedical Engineering, College of Life Science and Technology, Wuhan, Hubei, China
| | - Wenping Zeng
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Yan Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Jiuping Ding
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
- * E-mail: (PH); (JD)
| | - Panpan Hou
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, 63130, United States
- * E-mail: (PH); (JD)
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37
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Zhong XZ, Sun X, Cao Q, Dong G, Schiffmann R, Dong XP. BK channel agonist represents a potential therapeutic approach for lysosomal storage diseases. Sci Rep 2016; 6:33684. [PMID: 27670435 PMCID: PMC5037385 DOI: 10.1038/srep33684] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/31/2016] [Indexed: 12/21/2022] Open
Abstract
Efficient lysosomal Ca2+ release plays an essential role in lysosomal trafficking. We have recently shown that lysosomal big conductance Ca2+-activated potassium (BK) channel forms a physical and functional coupling with the lysosomal Ca2+ release channel Transient Receptor Potential Mucolipin-1 (TRPML1). BK and TRPML1 forms a positive feedback loop to facilitate lysosomal Ca2+ release and subsequent lysosome membrane trafficking. However, it is unclear whether the positive feedback mechanism is common for other lysosomal storage diseases (LSDs) and whether BK channel agonists rescue abnormal lysosomal storage in LSDs. In this study, we assessed the effect of BK agonist, NS1619 and NS11021 in a number of LSDs including NPC1, mild cases of mucolipidosis type IV (ML4) (TRPML1-F408∆), Niemann-Pick type A (NPA) and Fabry disease. We found that TRPML1-mediated Ca2+ release was compromised in these LSDs. BK activation corrected the impaired Ca2+ release in these LSDs and successfully rescued the abnormal lysosomal storage of these diseases by promoting TRPML1-mediated lysosomal exocytosis. Our study suggests that BK channel activation stimulates the TRPML1-BK positive reinforcing loop to correct abnormal lysosomal storage in LSDs. Drugs targeting BK channel represent a potential therapeutic approach for LSDs.
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Affiliation(s)
- Xi Zoë Zhong
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, B3H 4R2, Nova Scotia, Canada
| | - Xue Sun
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, B3H 4R2, Nova Scotia, Canada
| | - Qi Cao
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, B3H 4R2, Nova Scotia, Canada
| | - Gaofeng Dong
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, B3H 4R2, Nova Scotia, Canada
| | - Raphael Schiffmann
- Institute of Metabolic Disease, Baylor Research Institute, 3812 Elm Street, Dallas, TX, 75226, USA
| | - Xian-Ping Dong
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, B3H 4R2, Nova Scotia, Canada
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Kshatri AS, Li Q, Yan J, Large RJ, Sergeant GP, McHale NG, Thornbury KD, Hollywood MA. Differential efficacy of GoSlo-SR compounds on BKα and BKαγ 1-4 channels. Channels (Austin) 2016; 11:66-78. [PMID: 27440457 DOI: 10.1080/19336950.2016.1213930] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Large conductance, voltage and Ca2+ activated K+ channels (BK channels) are abundantly expressed throughout the body and are important regulators of smooth muscle tone and neuronal excitability. Their dysfunction is implicated in various diseases including overactive bladder, hypertension and erectile dysfunction. Therefore, BK channel openers bear significant therapeutic potential to treat the above diseases. GoSlo-SR compounds were designed to be potent and efficacious BK channel openers. Although their structural activity relationships, activation in both BKα and BKαβ channels and the hypothetical mode of action of these compounds has been studied in detail in recent years, their effectiveness to open the BKαγ channels still remains unexplored. In this study, we have examined the efficacy of 3 closely related GoSlo-SR openers, GoSlo-SR-5-6 (SR-5-6), GoSlo-SR-5-44 (SR-5-44) and GoSlo-SR-5-130 (SR-5-130) using inside out patches on BKα channels coexpressed with 4 different LRRC (γ1-4) subunits in HEK293 cells. Our data suggests that the activation effects due to SR-5-6 were not significantly affected in the presence of γ1-4 subunits. Interestingly, the effects of more efficacious BK channel opener SR-5-44 were altered by different γ subunits. In cells expressing BKα channels, the shift in V1/2 (ΔV1/2) induced by SR-5-44 (3 μM) was -76 ± 3 mV, whereas it was significantly reduced by ∼70 % in BKαγ1 channels (ΔV1/2= -23 ± 3, p < 0.001, ANOVA). In BKαγ2 channels the ΔV1/2 was -36 ± 1 mV, which was less than that observed in BKαγ3 and BKαγ4 channels where the ΔV1/2 was -47 ± 5 mV, and -82 ± 5 mV, respectively. Additionally, the excitatory effects of a 'β specific' BK channel opener, SR-5-130 were only partially restored in the patches containing BKαγ1-4 channels. Together this data highlights that subtle modifications in GoSlo-SR structures alter their effectiveness on BK channels with accessory γ subunits and this study might provide a scaffold for the development of more tissue specific BK channel openers.
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Affiliation(s)
- Aravind S Kshatri
- a The Smooth Muscle Research Center, Dundalk Institute of Technology , Dundalk , Ireland
| | - Qin Li
- b Department of Anesthesiology and Preoperative Medicine , The University of Texas MD Anderson Cancer Center , Houston , TX , USA
| | - Jiusheng Yan
- b Department of Anesthesiology and Preoperative Medicine , The University of Texas MD Anderson Cancer Center , Houston , TX , USA
| | - Roddy J Large
- a The Smooth Muscle Research Center, Dundalk Institute of Technology , Dundalk , Ireland.,c Ion Channel Biotechnology Center, Dundalk Institute of Technology , Dundalk , Ireland
| | - Gerard P Sergeant
- a The Smooth Muscle Research Center, Dundalk Institute of Technology , Dundalk , Ireland.,c Ion Channel Biotechnology Center, Dundalk Institute of Technology , Dundalk , Ireland
| | - Noel G McHale
- a The Smooth Muscle Research Center, Dundalk Institute of Technology , Dundalk , Ireland.,c Ion Channel Biotechnology Center, Dundalk Institute of Technology , Dundalk , Ireland
| | - Keith D Thornbury
- a The Smooth Muscle Research Center, Dundalk Institute of Technology , Dundalk , Ireland.,c Ion Channel Biotechnology Center, Dundalk Institute of Technology , Dundalk , Ireland
| | - Mark A Hollywood
- a The Smooth Muscle Research Center, Dundalk Institute of Technology , Dundalk , Ireland.,c Ion Channel Biotechnology Center, Dundalk Institute of Technology , Dundalk , Ireland
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Hoshi T, Heinemann SH. Modulation of BK Channels by Small Endogenous Molecules and Pharmaceutical Channel Openers. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:193-237. [PMID: 27238265 DOI: 10.1016/bs.irn.2016.03.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Voltage- and Ca(2+)-activated K(+) channels of big conductance (BK channels) are abundantly found in various organs and their relevance for smooth muscle tone and neuronal signaling is well documented. Dysfunction of BK channels is implicated in an array of human diseases involving many organs including the nervous, pulmonary, cardiovascular, renal, and urinary systems. In humans a single gene (KCNMA1) encodes the pore-forming α subunit (Slo1) of BK channels, but the channel properties are variable because of alternative splicing, tissue- and subcellular-specific auxiliary subunits (β, γ), posttranslational modifications, and a multitude of endogenous signaling molecules directly affecting the channel function. Initiatives to develop drugs capable of activating BK channels (channel openers) therefore need to consider the tissue-specific variability of BK channel structure and the potential interference with endogenously produced regulatory factors. The atomic structural basis of BK channel function is only beginning to be revealed. However, building on detailed knowledge of BK channel function, including its single-channel characteristics, voltage- and Ca(2+) dependence of channel gating, and modulation by diffusible messengers, a multi-tier allosteric model of BK channel gating (Horrigan and Aldrich (HA) model) has become a valuable tool in studying modulation of the channel. Using the conceptual framework of the HA model, we here review the functional impact of endogenous modulatory factors and select small synthetic compounds that regulate BK channel activity. Furthermore, we devise experimental approaches for studying BK channel-drug interactions with the aim to classify BK-modulating substances according to their molecular mode of action.
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Affiliation(s)
- T Hoshi
- University of Pennsylvania, Philadelphia, PA, United States.
| | - S H Heinemann
- Friedrich Schiller University Jena & Jena University Hospital, Jena, Germany
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Abstract
BK channels are universal regulators of cell excitability, given their exceptional unitary conductance selective for K(+), joint activation mechanism by membrane depolarization and intracellular [Ca(2+)] elevation, and broad expression pattern. In this chapter, we discuss the structural basis and operational principles of their activation, or gating, by membrane potential and calcium. We also discuss how the two activation mechanisms interact to culminate in channel opening. As members of the voltage-gated potassium channel superfamily, BK channels are discussed in the context of archetypal family members, in terms of similarities that help us understand their function, but also seminal structural and biophysical differences that confer unique functional properties.
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Affiliation(s)
- A Pantazis
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, United States
| | - R Olcese
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, United States.
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Modulation of BK Channel Function by Auxiliary Beta and Gamma Subunits. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:51-90. [PMID: 27238261 DOI: 10.1016/bs.irn.2016.03.015] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The large-conductance, Ca(2+)- and voltage-activated K(+) (BK) channel is ubiquitously expressed in mammalian tissues and displays diverse biophysical or pharmacological characteristics. This diversity is in part conferred by channel modulation with different regulatory auxiliary subunits. To date, two distinct classes of BK channel auxiliary subunits have been identified: β subunits and γ subunits. Modulation of BK channels by the four auxiliary β (β1-β4) subunits has been well established and intensively investigated over the past two decades. The auxiliary γ subunits, however, were identified only very recently, which adds a new dimension to BK channel regulation and improves our understanding of the physiological functions of BK channels in various tissues and cell types. This chapter will review the current understanding of BK channel modulation by auxiliary β and γ subunits, especially the latest findings.
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Mede R, Klein M, Claus RA, Krieck S, Quickert S, Görls H, Neugebauer U, Schmitt M, Gessner G, Heinemann SH, Popp J, Bauer M, Westerhausen M. CORM-EDE1: A Highly Water-Soluble and Nontoxic Manganese-Based photoCORM with a Biogenic Ligand Sphere. Inorg Chem 2015; 55:104-13. [PMID: 26672620 DOI: 10.1021/acs.inorgchem.5b01904] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
[Mn(CO)5Br] reacts with cysteamine and 4-amino-thiophenyl with a ratio of 2:3 in refluxing tetrahydrofuran to the complexes of the type [{(OC)3Mn}2(μ-SCH2CH2NH3)3]Br2 (1, CORM-EDE1) and [{(OC)3Mn}2(μ-SC6H4-4-NH3)3]Br2 (2, CORM-EDE2). Compound 2 precipitates during refluxing of the tetrahydrofuran solution as a yellow solid whereas 1 forms a red oil that slowly solidifies. Recrystallization of 2 from water yields the HBr-free complex [{(OC)3Mn}2(μ-S-C6H4-4-NH2)2(μ-SC6H4-4-NH3)] (3). The n-propylthiolate ligand (which is isoelectronic to the bridging thiolate of 1) leads to the formation of the di- and tetranuclear complexes [(OC)4Mn(μ-S-nPr)2]2 and [(OC)3Mn(μ-S-nPr)]4. CORM-EDE1 possesses ideal properties to administer carbon monoxide to biological and medicinal tissues upon irradiation (photoCORM). Isolated crystalline CORM-EDE1 can be handled at ambient and aerobic conditions. This complex is nontoxic, highly soluble in water, and indefinitely stable therein in the absence of air and phosphate buffer. CORM-EDE1 is stable as frozen stock in aqueous solution without any limitations, and these stock solutions maintain their CO release properties. The reducing dithionite does not interact with CORM-EDE1, and therefore, the myoglobin assay represents a valuable tool to study the release kinetics of this photoCORM. After CO liberation, the formation of MnHPO4 in aqueous buffer solution can be verified.
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Affiliation(s)
- Ralf Mede
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena , Humboldtstraße, 8, D-07743 Jena, Germany
| | - Moritz Klein
- Leibniz Institute of Photonic Technology (IPHT) , Albert-Einstein-Straße 9, D-07745 Jena, Germany
| | - Ralf A Claus
- Center for Sepsis Control and Care (CSCC), Friedrich Schiller University Jena and Jena University Hospital , Erlanger Allee 101, D-07747 Jena, Germany
| | - Sven Krieck
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena , Humboldtstraße, 8, D-07743 Jena, Germany
| | - Stefanie Quickert
- Center for Molecular Biomedicine (CMB), Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital , Hans-Knöll-Straße 2, D-07745 Jena, Germany
| | - Helmar Görls
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena , Humboldtstraße, 8, D-07743 Jena, Germany
| | - Ute Neugebauer
- Leibniz Institute of Photonic Technology (IPHT) , Albert-Einstein-Straße 9, D-07745 Jena, Germany.,Center for Sepsis Control and Care (CSCC), Friedrich Schiller University Jena and Jena University Hospital , Erlanger Allee 101, D-07747 Jena, Germany
| | - Michael Schmitt
- Institute of Physical Chemistry, Friedrich Schiller University Jena , Helmholtzweg 4, D-07743 Jena, Germany
| | - Guido Gessner
- Center for Molecular Biomedicine (CMB), Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital , Hans-Knöll-Straße 2, D-07745 Jena, Germany
| | - Stefan H Heinemann
- Center for Molecular Biomedicine (CMB), Department of Biophysics, Friedrich Schiller University Jena and Jena University Hospital , Hans-Knöll-Straße 2, D-07745 Jena, Germany
| | - Jürgen Popp
- Leibniz Institute of Photonic Technology (IPHT) , Albert-Einstein-Straße 9, D-07745 Jena, Germany.,Center for Sepsis Control and Care (CSCC), Friedrich Schiller University Jena and Jena University Hospital , Erlanger Allee 101, D-07747 Jena, Germany.,Institute of Physical Chemistry, Friedrich Schiller University Jena , Helmholtzweg 4, D-07743 Jena, Germany
| | - Michael Bauer
- Center for Sepsis Control and Care (CSCC), Friedrich Schiller University Jena and Jena University Hospital , Erlanger Allee 101, D-07747 Jena, Germany
| | - Matthias Westerhausen
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena , Humboldtstraße, 8, D-07743 Jena, Germany
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Cui YM, Liu XL, Zhang WM, Lin HX, Ohwada T, Ido K, Sawada K. The synthesis and BK channel-opening activity of N-acylaminoalkyloxime derivatives of dehydroabietic acid. Bioorg Med Chem Lett 2015; 26:283-287. [PMID: 26707391 DOI: 10.1016/j.bmcl.2015.12.038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 11/25/2015] [Accepted: 12/11/2015] [Indexed: 11/16/2022]
Abstract
A series of N-acylaminoalkyloxime derivatives of dehydroabietic acid were synthesized and evaluated for BK channel-opening activities in an assay system of CHO-K1 cells expressing hBKα channels. The structure-activity relationship study revealed that a non-covalent interaction between the S atom of the 2-thiophene and the carbonyl O atom may contribute to conformation restriction for interaction with the ion channel. This research could guide the design and synthesis of novel abietane-based BK channel opener.
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Affiliation(s)
- Yong-Mei Cui
- Department of Chemistry, Innovative Drug Research Center, College of Sciences, Shanghai University, Shanghai 200444, China.
| | - Xin-Lan Liu
- Department of Chemistry, Innovative Drug Research Center, College of Sciences, Shanghai University, Shanghai 200444, China
| | - Wen-Ming Zhang
- Department of Chemistry, Innovative Drug Research Center, College of Sciences, Shanghai University, Shanghai 200444, China
| | - Hai-Xia Lin
- Department of Chemistry, Innovative Drug Research Center, College of Sciences, Shanghai University, Shanghai 200444, China
| | - Tomohiko Ohwada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan.
| | - Katsutoshi Ido
- Tsukuba Research Laboratories, Eisai Co. Ltd, Ibaraki 300-2635, Japan
| | - Kohei Sawada
- Tsukuba Research Laboratories, Eisai Co. Ltd, Ibaraki 300-2635, Japan
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Tian Y, Ullrich F, Xu R, Heinemann SH, Hou S, Hoshi T. Two distinct effects of PIP2 underlie auxiliary subunit-dependent modulation of Slo1 BK channels. ACTA ACUST UNITED AC 2015; 145:331-43. [PMID: 25825171 PMCID: PMC4380209 DOI: 10.1085/jgp.201511363] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP2) plays a critical role in modulating the function of numerous ion channels, including large-conductance Ca(2+)- and voltage-dependent K(+) (BK, Slo1) channels. Slo1 BK channel complexes include four pore-forming Slo1 (α) subunits as well as various regulatory auxiliary subunits (β and γ) that are expressed in different tissues. We examined the molecular and biophysical mechanisms underlying the effects of brain-derived PIP2 on human Slo1 BK channel complexes with different subunit compositions that were heterologously expressed in human embryonic kidney cells. PIP2 inhibited macroscopic currents through Slo1 channels without auxiliary subunits and through Slo1 + γ1 complexes. In contrast, PIP2 markedly increased macroscopic currents through Slo1 + β1 and Slo1 + β4 channel complexes and failed to alter macroscopic currents through Slo1 + β2 and Slo1 + β2 Δ2-19 channel complexes. Results obtained at various membrane potentials and divalent cation concentrations suggest that PIP2 promotes opening of the ion conduction gate in all channel types, regardless of the specific subunit composition. However, in the absence of β subunits positioned near the voltage-sensor domains (VSDs), as in Slo1 and probably Slo1 + γ1, PIP2 augments the negative surface charge on the cytoplasmic side of the membrane, thereby shifting the voltage dependence of VSD-mediated activation in the positive direction. When β1 or β4 subunits occupy the space surrounding the VSDs, only the stimulatory effect of PIP2 is evident. The subunit compositions of native Slo1 BK channels differ in various cell types; thus, PIP2 may exert distinct tissue- and divalent cation-dependent modulatory influences.
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Affiliation(s)
- Yutao Tian
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104
| | - Florian Ullrich
- Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital, D-07745 Jena, Germany
| | - Rong Xu
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104
| | - Stefan H Heinemann
- Department of Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University Jena and Jena University Hospital, D-07745 Jena, Germany
| | - Shangwei Hou
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Toshinori Hoshi
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104
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2014 Conway review lecture, Royal Academy of Medicine in Ireland: “S6, drugs and RCK and Bowl”. Ir J Med Sci 2015; 185:1-10. [PMID: 26477033 DOI: 10.1007/s11845-015-1362-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/21/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND The Conway Review Lecture is held annually by the Royal Academy of Medicine in Ireland Biomedical Sciences Section, to remember the life and scientific work of a world class Irish scientist, Professor Edward J Conway. AIMS This years lecture will focus on large conductance Ca2+ activated K+ (BK) channels and aims to describe how a combination of techniques can be used to unravel drug effects on ion channels at a molecular level. METHODS Experiments were performed using a range of techniques including patch clamp electrophysiology, mutagenesis, structural biology and mathematical modeling. RESULTS Our data suggest that the novel BK channel opener GoSlo-SR-5-6 mediates its effects via an interaction with 2 residues on S6 (S317 and I326) and a residue on the S4/S5 linker (L227). CONCLUSIONS We hypothesize that this novel opener activates BK channels by altering an interaction between the S4/S5 linker and the pore-forming S6 transmembrane helix.
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Ottosson NE, Wu X, Nolting A, Karlsson U, Lund PE, Ruda K, Svensson S, Konradsson P, Elinder F. Resin-acid derivatives as potent electrostatic openers of voltage-gated K channels and suppressors of neuronal excitability. Sci Rep 2015; 5:13278. [PMID: 26299574 PMCID: PMC4547393 DOI: 10.1038/srep13278] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 07/13/2015] [Indexed: 11/12/2022] Open
Abstract
Voltage-gated ion channels generate cellular excitability, cause diseases when mutated, and act as drug targets in hyperexcitability diseases, such as epilepsy, cardiac arrhythmia and pain. Unfortunately, many patients do not satisfactorily respond to the present-day drugs. We found that the naturally occurring resin acid dehydroabietic acid (DHAA) is a potent opener of a voltage-gated K channel and thereby a potential suppressor of cellular excitability. DHAA acts via a non-traditional mechanism, by electrostatically activating the voltage-sensor domain, rather than directly targeting the ion-conducting pore domain. By systematic iterative modifications of DHAA we synthesized 71 derivatives and found 32 compounds more potent than DHAA. The most potent compound, Compound 77, is 240 times more efficient than DHAA in opening a K channel. This and other potent compounds reduced excitability in dorsal root ganglion neurons, suggesting that resin-acid derivatives can become the first members of a new family of drugs with the potential for treatment of hyperexcitability diseases.
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Affiliation(s)
- Nina E Ottosson
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Xiongyu Wu
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Andreas Nolting
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Urban Karlsson
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Per-Eric Lund
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Katinka Ruda
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Stefan Svensson
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Peter Konradsson
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Fredrik Elinder
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
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Large RJ, Kshatri A, Webb TI, Roy S, Akande A, Bradley E, Sergeant GP, Thornbury KD, McHale NG, Hollywood MA. Effects of the novel BK (KCa 1.1) channel opener GoSlo-SR-5-130 are dependent on the presence of BKβ subunits. Br J Pharmacol 2015; 172:2544-56. [PMID: 25598230 DOI: 10.1111/bph.13085] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 12/12/2014] [Accepted: 01/02/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND AND PURPOSE GoSlo-SR compounds are efficacious BK (KCa 1.1) channel openers, but little is known about their mechanism of action or effect on bladder contractility. We examined the effects of two closely related compounds on BK currents and bladder contractions. EXPERIMENTAL APPROACH A combination of electrophysiology, molecular biology and synthetic chemistry was used to examine the effects of two novel channel agonists on BK channels from bladder smooth muscle cells and in HEK cells expressing BKα alone or in combination with either β1 or β4 subunits. KEY RESULTS GoSlo-SR-5-6 shifted the voltage required for half maximal activation (V1/2 ) of BK channels approximately -100 mV, irrespective of the presence of regulatory β subunits. The deaminated derivative, GoSlo-SR-5-130, also shifted the activation V1/2 in smooth muscle cells by approximately -100 mV; however, this was reduced by ∼80% in HEK cells expressing only BKα subunits. When β1 or β4 subunits were co-expressed with BKα, efficacy was restored. GoSlo-SR-5-130 caused a concentration-dependent reduction in spontaneous bladder contraction amplitude and this was abolished by iberiotoxin, consistent with an effect on BK channels. CONCLUSIONS AND IMPLICATIONS GoSlo-SR-5-130 required β1 or β4 subunits to mediate its full effects, whereas GoSlo-SR-5-6 worked equally well in the absence or presence of β subunits. GoSlo-SR-5-130 inhibited spontaneous bladder contractions by activating BK channels. The novel BK channel opener, GoSlo-SR-5-130, is approximately fivefold more efficacious on BK channels with regulatory β subunits and may be a useful scaffold in the development of drugs to treat diseases such as overactive bladder.
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Affiliation(s)
- R J Large
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland
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Yang H, Zhang G, Cui J. BK channels: multiple sensors, one activation gate. Front Physiol 2015; 6:29. [PMID: 25705194 PMCID: PMC4319557 DOI: 10.3389/fphys.2015.00029] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 01/19/2015] [Indexed: 01/01/2023] Open
Abstract
Ion transport across cell membranes is essential to cell communication and signaling. Passive ion transport is mediated by ion channels, membrane proteins that create ion conducting pores across cell membrane to allow ion flux down electrochemical gradient. Under physiological conditions, majority of ion channel pores are not constitutively open. Instead, structural region(s) within these pores breaks the continuity of the aqueous ion pathway, thereby serves as activation gate(s) to control ions flow in and out. To achieve spatially and temporally regulated ion flux in cells, many ion channels have evolved sensors to detect various environmental stimuli or the metabolic states of the cell and trigger global conformational changes, thereby dynamically operate the opening and closing of their activation gate. The sensors of ion channels can be broadly categorized as chemical sensors and physical sensors to respond to chemical (such as neural transmitters, nucleotides and ions) and physical (such as voltage, mechanical force and temperature) signals, respectively. With the rapidly growing structural and functional information of different types of ion channels, it is now critical to understand how ion channel sensors dynamically control their gates at molecular and atomic level. The voltage and Ca2+ activated BK channels, a K+ channel with an electrical sensor and multiple chemical sensors, provide a unique model system for us to understand how physical and chemical energy synergistically operate its activation gate.
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Affiliation(s)
- Huanghe Yang
- Ion Channel Research Unit, Duke University Medical Center Durham, NC, USA ; Department of Biochemistry, Duke University Medical Center Durham, NC, USA
| | - Guohui Zhang
- Department of Biomedical Engineering, Washington University in Saint Louis St. Louis, MO, USA
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in Saint Louis St. Louis, MO, USA ; Cardiac Bioelectricity and Arrhythmia Center, Washington University in Saint Louis St. Louis, MO, USA ; Center for The Investigation of Membrane Excitability Disorders, Washington University in Saint Louis St. Louis, MO, USA
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Molecular mechanisms underlying the effect of the novel BK channel opener GoSlo: involvement of the S4/S5 linker and the S6 segment. Proc Natl Acad Sci U S A 2015; 112:2064-9. [PMID: 25653338 DOI: 10.1073/pnas.1400555112] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
GoSlo-SR-5-6 is a novel large-conductance Ca(2+)-activated K(+) (BK) channel agonist that shifts the activation V1/2 of these channels in excess of -100 mV when applied at a concentration of 10 μM. Although the structure-activity relationship of this family of molecules has been established, little is known about how they open BK channels. To help address this, we used a combination of electrophysiology, mutagenesis, and mathematical modeling to investigate the molecular mechanisms underlying the effect of GoSlo-SR-5-6. Our data demonstrate that the effects of this agonist are practically abolished when three point mutations are made: L227A in the S4/S5 linker in combination with S317R and I326A in the S6C region. Our data suggest that GoSlo-SR-5-6 interacts with the transmembrane domain of the channel to enhance pore opening. The Horrigan-Aldrich model suggests that GoSlo-SR-5-6 works by stabilizing the open conformation of the channel and the activated state of the voltage sensors, yet decouples the voltage sensors from the pore gate.
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50
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Clements RT, Terentyev D, Sellke FW. Ca 2+-Activated K + Channels as Therapeutic Targets for Myocardial and Vascular Protection. Circ J 2015; 79:455-62. [DOI: 10.1253/circj.cj-15-0015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Richard T. Clements
- Department of Surgery, Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University
| | - Dmitry Terentyev
- Department of Medicine, Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University
| | - Frank W. Sellke
- Department of Surgery, Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University
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