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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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Zhang Y, Fan S, He L, Li L. The ZDHHC13/ZDHHC17 subfamily: From biological functions to therapeutic targets of diseases. Pharmacol Res 2024; 209:107418. [PMID: 39306022 DOI: 10.1016/j.phrs.2024.107418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 09/11/2024] [Accepted: 09/11/2024] [Indexed: 10/03/2024]
Abstract
The ZDHHC13/ZDHHC17 subfamily belongs to the zinc finger DHHC-domain containing (ZDHHC) family, including ZDHHC13 and ZDHHC17. Recent studies have shown that the ZDHHC13/ZDHHC17 subfamily is involved in various pathological and physiological processes, including S-palmitoylation, Mg2+ transport, and CALCOCO1-mediated Golgiphagy. Moreover, the ZDHHC13/ZDHHC17 subfamily plays a crucial role in the occurrence and development of many diseases, including Huntington disease (HD), osteoporosis, atopic dermatitis, diabetes, and cancer. In the present review, we describe the distribution, structure, and post-translational modifications (PTMs) of the ZDHHC13/ZDHHC17 subfamily. Moreover, we effectively summarize the biological functions and associated diseases of this subfamily. Given the pleiotropy of the ZDHHC13/ZDHHC17 subfamily, it is imperative to conduct further research on its members to comprehend the pertinent pathophysiological mechanisms and to devise tactics for managing and controlling various diseases.
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Affiliation(s)
- Ying Zhang
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang, Hunan 421001, China
| | - Sisi Fan
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang, Hunan 421001, China
| | - Lu He
- The First Affiliated Hospital, Department of Neurosurgery, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China.
| | - Lanfang Li
- Institute of Pharmacy and Pharmacology, Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hengyang, Hunan 421001, China.
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3
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Ferraguto C, Piquemal-Lagoueillat M, Lemaire V, Moreau MM, Trazzi S, Uguagliati B, Ciani E, Bertrand SS, Louette E, Bontempi B, Pietropaolo S. Therapeutic efficacy of the BKCa channel opener chlorzoxazone in a mouse model of Fragile X syndrome. Neuropsychopharmacology 2024:10.1038/s41386-024-01956-6. [PMID: 39223257 DOI: 10.1038/s41386-024-01956-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 06/30/2024] [Accepted: 07/23/2024] [Indexed: 09/04/2024]
Abstract
Fragile X syndrome (FXS) is an X-linked neurodevelopmental disorder characterized by several behavioral abnormalities, including hyperactivity, anxiety, sensory hyper-responsiveness, and autistic-like symptoms such as social deficits. Despite considerable efforts, effective pharmacological treatments are still lacking, prompting the need for exploring the therapeutic value of existing drugs beyond their original approved use. One such repurposed drug is chlorzoxazone which is classified as a large-conductance calcium-dependent potassium (BKCa) channel opener. Reduced BKCa channel functionality has been reported in FXS patients, suggesting that molecules activating these channels could serve as promising treatments for this syndrome. Here, we sought to characterize the therapeutic potential of chlorzoxazone using the Fmr1-KO mouse model of FXS which recapitulates the main phenotypes of FXS, including BKCa channel alterations. Chlorzoxazone, administered either acutely or chronically, rescued hyperactivity and acoustic hyper-responsiveness as well as impaired social interactions exhibited by Fmr1-KO mice. Chlorzoxazone was more efficacious in alleviating these phenotypes than gaboxadol and metformin, two repurposed treatments for FXS that do not target BKCa channels. Systemic administration of chlorzoxazone modulated the neuronal activity-dependent gene c-fos in selected brain areas of Fmr1-KO mice, corrected aberrant hippocampal dendritic spines, and was able to rescue impaired BKCa currents recorded from hippocampal and cortical neurons of these mutants. Collectively, these findings provide further preclinical support for BKCa channels as a valuable therapeutic target for treating FXS and encourage the repurposing of chlorzoxazone for clinical applications in FXS and other related neurodevelopmental diseases.
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Affiliation(s)
| | | | - Valerie Lemaire
- Univ. Bordeaux, CNRS, EPHE, INCIA, UMR 5287, Bordeaux, France
| | - Maïté M Moreau
- Univ. Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Stefania Trazzi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Beatrice Uguagliati
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Elisabetta Ciani
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | | | | | - Bruno Bontempi
- Univ. Bordeaux, CNRS, EPHE, INCIA, UMR 5287, Bordeaux, France
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4
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Lorenz J, Eisenhardt C, Mittermair T, Kulle AE, Holterhus PM, Fobker M, Boenigk W, Nordhoff V, Behre HM, Strünker T, Brenker C. The sperm-specific K + channel Slo3 is inhibited by albumin and steroids contained in reproductive fluids. Front Cell Dev Biol 2024; 12:1275116. [PMID: 39310227 PMCID: PMC11413451 DOI: 10.3389/fcell.2024.1275116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 07/19/2024] [Indexed: 09/25/2024] Open
Abstract
To locate and fertilize the egg, sperm probe the varying microenvironment prevailing at different stages during their journey across the female genital tract. To this end, they are equipped with a unique repertoire of mostly sperm-specific proteins. In particular, the flagellar Ca2+ channel CatSper has come into focus as a polymodal sensor used by human sperm to register ligands released into the female genital tract. Here, we provide the first comprehensive study on the pharmacology of the sperm-specific human Slo3 channel, shedding light on its modulation by reproductive fluids and their constituents. We show that seminal fluid and contained prostaglandins and Zn2+ do not affect the channel, whereas human Slo3 is inhibited in a non-genomic fashion by diverse steroids as well as by albumin, which are released into the oviduct along with the egg. This indicates that not only CatSper but also Slo3 harbours promiscuous ligand-binding sites that can accommodate structurally diverse molecules, suggesting that Slo3 is involved in chemosensory signalling in human sperm.
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Affiliation(s)
- Johannes Lorenz
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Clara Eisenhardt
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Teresa Mittermair
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Alexandra E. Kulle
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, Christian-Albrechts-University, Kiel, Germany
| | - Paul Martin Holterhus
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, Christian-Albrechts-University, Kiel, Germany
| | - Manfred Fobker
- Center for Laboratory Medicine, University Hospital, Münster, Germany
| | - Wolfgang Boenigk
- Max Planck Institute for Neurobiology of Behaviour—Caesar, Bonn, Germany
| | - Verena Nordhoff
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | | | - Timo Strünker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Christoph Brenker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
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5
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Celik B, Leal AF, Tomatsu S. Potential Targeting Mechanisms for Bone-Directed Therapies. Int J Mol Sci 2024; 25:8339. [PMID: 39125906 PMCID: PMC11312506 DOI: 10.3390/ijms25158339] [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: 05/21/2024] [Revised: 07/23/2024] [Accepted: 07/24/2024] [Indexed: 08/12/2024] Open
Abstract
Bone development is characterized by complex regulation mechanisms, including signal transduction and transcription factor-related pathways, glycobiological processes, cellular interactions, transportation mechanisms, and, importantly, chemical formation resulting from hydroxyapatite. Any abnormal regulation in the bone development processes causes skeletal system-related problems. To some extent, the avascularity of cartilage and bone makes drug delivery more challenging than that of soft tissues. Recent studies have implemented many novel bone-targeting approaches to overcome drawbacks. However, none of these strategies fully corrects skeletal dysfunction, particularly in growth plate-related ones. Although direct recombinant enzymes (e.g., Vimizim for Morquio, Cerezyme for Gaucher, Elaprase for Hunter, Mepsevii for Sly diseases) or hormone infusions (estrogen for osteoporosis and osteoarthritis), traditional gene delivery (e.g., direct infusion of viral or non-viral vectors with no modifications on capsid, envelope, or nanoparticles), and cell therapy strategies (healthy bone marrow or hematopoietic stem cell transplantation) partially improve bone lesions, novel delivery methods must be addressed regarding target specificity, less immunogenicity, and duration in circulation. In addition to improvements in bone delivery, potential regulation of bone development mechanisms involving receptor-regulated pathways has also been utilized. Targeted drug delivery using organic and inorganic compounds is a promising approach in mostly preclinical settings and future clinical translation. This review comprehensively summarizes the current bone-targeting strategies based on bone structure and remodeling concepts while emphasizing potential approaches for future bone-targeting systems.
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Affiliation(s)
- Betul Celik
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA;
- Nemours Children’s Health, 1600 Rockland Rd., Wilmington, DE 19803, USA;
| | - Andrés Felipe Leal
- Nemours Children’s Health, 1600 Rockland Rd., Wilmington, DE 19803, USA;
- Institute for the Study of Inborn Errors of Metabolism, Faculty of Science, Pontificia Universidad Javeriana, Bogotá 110231, Colombia
| | - Shunji Tomatsu
- Nemours Children’s Health, 1600 Rockland Rd., Wilmington, DE 19803, USA;
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501-1193, Japan
- Department of Pediatrics, Thomas Jefferson University, Philadelphia, PA 19144, USA
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6
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Kshatri A, Rivero-Pérez B, Giraldez T. Subunit-specific inhibition of BK channels by piperine. Biophys J 2024; 123:1942-1953. [PMID: 37700524 PMCID: PMC11309970 DOI: 10.1016/j.bpj.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 08/03/2023] [Accepted: 09/08/2023] [Indexed: 09/14/2023] Open
Abstract
Piperine is the principal alkaloid present in black pepper and is well-known for its diverse pharmacological effects, including inhibition of different ion channels. Large conductance Ca2+-activated K+ channels (BK) are widely expressed across several tissues and play a vital role in many physiological functions. In this study, we investigated the pharmacological effects of piperine on various BK channel subunit compositions (BKα, BKαβ1,4, BKαγ1,3) expressed in HEK293T cells. Piperine in zero Ca2+ reversibly inhibited currents from the pore-forming BKα channels in a dose-dependent manner with a half-maximal inhibitory concentration (IC50) of 4.8 μM. Elevating the internal Ca2+ concentration from 0 to 100 μM significantly attenuated the inhibitory effects of piperine on BKα channels. The mutation G311S in the pore domain failed to alter the modulatory effects of piperine, whereas deletion of the entire cytoplasmic domain from BKα channels ablated its inhibitory effects. Addition of either BKβ1 or β4 regulatory subunits did not alter the efficacy of piperine on BKα channels. Interestingly, co-expression of either BKγ1 or BKγ3 subunits greatly diminished the ability of piperine to inhibit BKα channels. Our findings demonstrate that piperine is a potent natural modulator of BKα/BKαβ1,4 subunits but not BKαγ1,3 subunits. The mechanism of piperine modulation appeared to be allosteric and differs from that of other BK pore blockers (paxilline, peptide toxins, and quaternary ammonium compounds). Together, our results unravel the potential of piperine to inhibit BK channels, providing a new tool to explore mechanisms underlying the effects of regulatory subunits.
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Affiliation(s)
- Aravind Kshatri
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain; Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Belinda Rivero-Pérez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain; Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Teresa Giraldez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain; Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain.
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7
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Li Q, Chen G, Yan J. Transmembrane determinants of voltage-gating differences between BK (Slo1) and Slo3 channels. Biophys J 2024; 123:2154-2166. [PMID: 38637987 PMCID: PMC11309983 DOI: 10.1016/j.bpj.2024.04.016] [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: 11/17/2023] [Revised: 02/01/2024] [Accepted: 04/15/2024] [Indexed: 04/20/2024] Open
Abstract
Voltage-gated potassium channels are critical in modulating cellular excitability, with Slo (slowpoke) channels forming a unique family characterized by their large conductance and dual regulation by electrical signals and intracellular messengers. Despite their structural and evolutionary similarities, Slo1 and Slo3 channels exhibit significant differences in their voltage-gating properties. This study investigates the molecular determinants that differentiate the voltage-gating properties of human Slo1 and mouse Slo3 channels. Utilizing Slo1/Slo3 chimeras, we pinpointed the selectivity filter region as a key factor in the Slo3 channel's reduced conductance at negative voltages. The S6 transmembrane (TM) segment was identified as pivotal for the Slo3 channel's biphasic deactivation kinetics at these voltages. Additionally, the S4 and S6 TM segments were found to be responsible for the gradual slope in the Slo3 channel's conductance-voltage relationship, while multiple TM regions appear to be involved in the Slo3 channel's requirement of strong depolarization for activation. Mutations in the Slo1's S5 and S6 TM segments revealed three residues (I233, L302, and M304) that likely play a crucial role in the allosteric coupling between the voltage sensors and the pore gate.
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Affiliation(s)
- Qin Li
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Guanxing Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas.
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8
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Hu L, Chen W, Qian A, Li YP. Wnt/β-catenin signaling components and mechanisms in bone formation, homeostasis, and disease. Bone Res 2024; 12:39. [PMID: 38987555 PMCID: PMC11237130 DOI: 10.1038/s41413-024-00342-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 04/27/2024] [Accepted: 05/12/2024] [Indexed: 07/12/2024] Open
Abstract
Wnts are secreted, lipid-modified proteins that bind to different receptors on the cell surface to activate canonical or non-canonical Wnt signaling pathways, which control various biological processes throughout embryonic development and adult life. Aberrant Wnt signaling pathway underlies a wide range of human disease pathogeneses. In this review, we provide an update of Wnt/β-catenin signaling components and mechanisms in bone formation, homeostasis, and diseases. The Wnt proteins, receptors, activators, inhibitors, and the crosstalk of Wnt signaling pathways with other signaling pathways are summarized and discussed. We mainly review Wnt signaling functions in bone formation, homeostasis, and related diseases, and summarize mouse models carrying genetic modifications of Wnt signaling components. Moreover, the therapeutic strategies for treating bone diseases by targeting Wnt signaling, including the extracellular molecules, cytosol components, and nuclear components of Wnt signaling are reviewed. In summary, this paper reviews our current understanding of the mechanisms by which Wnt signaling regulates bone formation, homeostasis, and the efforts targeting Wnt signaling for treating bone diseases. Finally, the paper evaluates the important questions in Wnt signaling to be further explored based on the progress of new biological analytical technologies.
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Affiliation(s)
- Lifang Hu
- Laboratory for Bone Metabolism, Xi'an Key Laboratory of Special Medicine and Health Engineering, Key Laboratory for Space Biosciences and Biotechnology, Research Center for Special Medicine and Health Systems Engineering, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, 710072, China
| | - Wei Chen
- Division in Cellular and Molecular Medicine, Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, Tulane University, New Orleans, LA, 70112, USA
| | - Airong Qian
- Laboratory for Bone Metabolism, Xi'an Key Laboratory of Special Medicine and Health Engineering, Key Laboratory for Space Biosciences and Biotechnology, Research Center for Special Medicine and Health Systems Engineering, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, 710072, China.
| | - Yi-Ping Li
- Division in Cellular and Molecular Medicine, Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, Tulane University, New Orleans, LA, 70112, USA.
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Whelan SCM, Mutchler SM, Han A, Priestley C, Satlin LM, Kleyman TR, Shi S. Kcnma1 alternative splicing in mouse kidney: regulation during development and by dietary K + intake. Am J Physiol Renal Physiol 2024; 327:F49-F60. [PMID: 38779757 DOI: 10.1152/ajprenal.00100.2024] [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: 03/29/2024] [Revised: 04/30/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
The pore-forming α-subunit of the large-conductance K+ (BK) channel is encoded by a single gene, KCNMA1. BK channel-mediated K+ secretion in the kidney is crucial for overall renal K+ homeostasis in both physiological and pathological conditions. BK channels achieve phenotypic diversity by various mechanisms, including substantial exon rearrangements at seven major alternative splicing sites. However, KCNMA1 alternative splicing in the kidney has not been characterized. The present study aims to identify the major splice variants of mouse Kcnma1 in whole kidney and distal nephron segments. We designed primers that specifically cross exons within each alternative splice site of mouse Kcnma1 and performed real-time quantitative RT-PCR (RT-qPCR) to quantify relative abundance of each splice variant. Our data suggest that Kcnma1 splice variants within mouse kidney are less diverse than in the brain. During postnatal kidney development, most Kcnma1 splice variants at site 5 and the COOH terminus increase in abundance over time. Within the kidney, the regulation of Kcnma1 alternative exon splicing within these two sites by dietary K+ loading is both site and sex specific. In microdissected distal tubules, the Kcnma1 alternative splicing profile, as well as its regulation by dietary K+, are distinctly different than in the whole kidney, suggesting segment and/or cell type specificity in Kcnma1 splicing events. Overall, our data provide evidence that Kcnma1 alternative splicing is regulated during postnatal development and may serve as an important adaptive mechanism to dietary K+ loading in mouse kidney.NEW & NOTEWORTHY We identified the major Kcnma1 splice variants that are specifically expressed in the whole mouse kidney or aldosterone-sensitive distal nephron segments. Our data suggest that Kcnma1 alternative splicing is developmentally regulated and subject to changes in dietary K+.
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Affiliation(s)
| | - Stephanie M Mutchler
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Agnes Han
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Catherine Priestley
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Thomas R Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Shujie Shi
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
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10
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Jarva TM, Phillips NM, Von Eiff C, Poulakis GR, Naylor G, Feldheim KA, Flynt AS. Gene expression, evolution, and the genetics of electrosensing in the smalltooth sawfish, Pristis pectinata. Ecol Evol 2024; 14:e11260. [PMID: 38694751 PMCID: PMC11057056 DOI: 10.1002/ece3.11260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 03/14/2024] [Accepted: 03/28/2024] [Indexed: 05/04/2024] Open
Abstract
Sawfishes (Pristidae) are large, highly threatened rays named for their tooth-studded rostrum, which is used for prey sensing and capture. Of all five species, the smalltooth sawfish, Pristis pectinata, has experienced the greatest decline in range, currently found in only ~20% of its historic range. To better understand the genetic underpinnings of these taxonomically and morphologically unique animals, we collected transcriptomic data from several tissue types, mapped them to the recently completed reference genome, and contrasted the patterns observed with comparable data from other elasmobranchs. Evidence of positive selection was detected in 79 genes in P. pectinata, several of which are involved in growth factor/receptor tyrosine kinase signaling and body symmetry and may be related to the unique morphology of sawfishes. Changes in these genes may impact cellular responses to environmental conditions such as temperature, dissolved oxygen, and salinity. Data acquired also allow for examination of the molecular components of P. pectinata electrosensory systems, which are highly developed in sawfishes and have likely been influential in their evolutionary success.
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Affiliation(s)
- Taiya M. Jarva
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
| | - Nicole M. Phillips
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
| | - Cory Von Eiff
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
| | - Gregg R. Poulakis
- Charlotte Harbor Field LaboratoryFish and Wildlife Research Institute, Florida Fish and Wildlife Conservation CommissionPort CharlotteFloridaUSA
| | - Gavin Naylor
- Florida Program for Shark ResearchUniversity of FloridaGainesvilleFloridaUSA
| | - Kevin A. Feldheim
- Pritzker Laboratory for Molecular Systematics and Evolution, the Field MuseumChicagoIllinoisUSA
| | - Alex S. Flynt
- School of Biological, Environmental, and Earth SciencesThe University of Southern MississippiHattiesburgMississippiUSA
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11
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Redhardt M, Raunser S, Raisch T. Cryo-EM structure of the Slo1 potassium channel with the auxiliary γ1 subunit suggests a mechanism for depolarization-independent activation. FEBS Lett 2024; 598:875-888. [PMID: 38553946 DOI: 10.1002/1873-3468.14863] [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: 11/04/2023] [Revised: 02/20/2024] [Accepted: 03/06/2024] [Indexed: 04/23/2024]
Abstract
Mammalian Ca2+-dependent Slo K+ channels can stably associate with auxiliary γ subunits which fundamentally alter their behavior. By a so far unknown mechanism, the four γ subunits reduce the need for voltage-dependent activation and, thereby, allow Slo to open independently of an action potential. Here, using cryo-EM, we reveal how the transmembrane helix of γ1/LRRC26 binds and presumably stabilizes the activated voltage-sensor domain of Slo1. The activation is further enhanced by an intracellular polybasic stretch which locally changes the charge gradient across the membrane. Our data provide a possible explanation for Slo1 regulation by the four γ subunits and also their different activation efficiencies. This suggests a novel activation mechanism of voltage-gated ion channels by auxiliary subunits.
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Affiliation(s)
- Milena Redhardt
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Tobias Raisch
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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12
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Cordero Padilla K, Monefeldt GA, Guevárez Galán A, Marrero HG, Lloret-Torres ME, Velázquez-Marrero C. BK ZERO isoform HEK293 stably transfected cell lines differing 3'UTRs to assess miR-9 regulation. PLoS One 2024; 19:e0298966. [PMID: 38502673 PMCID: PMC10950231 DOI: 10.1371/journal.pone.0298966] [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: 09/26/2023] [Accepted: 01/30/2024] [Indexed: 03/21/2024] Open
Abstract
Research has identified the large conductance voltage- and calcium-activated potassium channel (BK) as a key regulator of neuronal excitability genetically associated to behavioral alcohol tolerance. Sensitivity to ethanol at the molecular level is characterized by acute potentiation of channel activity. BK isoforms show variations in alcohol sensitivity and are differentially distributed on the plasma membrane surface in response to prolonged exposure. MicroRNA (MiRNA) targeting of alcohol-sensitive isoforms coupled with active internalization of BK channels in response to ethanol are believed to be key in establishing homeostatic adaptations that produce persistent changes within the plasma membrane of neurons. In fact, microRNA 9 (miR-9) upregulated expression is a key event in persistent alcohol tolerance mediating acute EtOH desensitization of BK channels. The exact nature of these interactions remains a current topic of discussion. To further study the effects of miR-9 on the expression and distribution of BK channel isoforms we designed an experimental model by transfecting human BK channel isoforms ZERO heterologous constructs in human embryonic kidney cells 293 (HEK293) cells respectively expressing 2.1 (miR-9 responsive), 2.2 (unresponsive) and control (no sequence) 3'untranslated region (3'UTR) miRNA recognition sites. We used imaging techniques to characterize the stably transfected monoclonal cell lines, and electrophysiology to validate channel activity. Finally, we used immunocytochemistry to validate isoform responsiveness to miR-9. Our findings suggest the cell lines were successfully transfected to express either the 2.1 or 2.2 version of ZERO. Patch clamp recordings confirm that these channels retain their functionality and immunohistochemistry shows differential responses to miR-9, making these cells viable for use in future alcohol dependence studies.
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Affiliation(s)
- Katherine Cordero Padilla
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
- Windsor University School of Medicine, St. Kitts, West Indies
| | - Gerardo Alvarado Monefeldt
- Department of Biology, University of Puerto Rico Cayey Campus, Cayey, Puerto Rico
- Samuel Merritt University, Oakland, California, United States of America
| | - Adriel Guevárez Galán
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
- Department of Biology, University of Puerto Rico Bayamón Campus, Bayamón, Puerto Rico
| | - Hector G. Marrero
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Mario E. Lloret-Torres
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Cristina Velázquez-Marrero
- Department of Anatomy and Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
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13
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Morris PG, Taylor JD, Paton JFR, Nogaret A. Single shot detection of alterations across multiple ionic currents from assimilation of cell membrane dynamics. Sci Rep 2024; 14:6031. [PMID: 38472404 DOI: 10.1038/s41598-024-56576-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/08/2024] [Indexed: 03/14/2024] Open
Abstract
The dysfunction of ion channels is a causative factor in a variety of neurological diseases, thereby defining the implicated channels as key drug targets. The detection of functional changes in multiple specific ionic currents currently presents a challenge, particularly when the neurological causes are either a priori unknown, or are unexpected. Traditional patch clamp electrophysiology is a powerful tool in this regard but is low throughput. Here, we introduce a single-shot method for detecting alterations amongst a range of ion channel types from subtle changes in membrane voltage in response to a short chaotically driven current clamp protocol. We used data assimilation to estimate the parameters of individual ion channels and from these we reconstructed ionic currents which exhibit significantly lower error than the parameter estimates. Such reconstructed currents thereby become sensitive predictors of functional alterations in biological ion channels. The technique correctly predicted which ionic current was altered, and by approximately how much, following pharmacological blockade of BK, SK, A-type K+ and HCN channels in hippocampal CA1 neurons. We anticipate this assay technique could aid in the detection of functional changes in specific ionic currents during drug screening, as well as in research targeting ion channel dysfunction.
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Affiliation(s)
- Paul G Morris
- Department of Physics, University of Bath, Claverton Down, Bath, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Joseph D Taylor
- Department of Physics, University of Bath, Claverton Down, Bath, UK
| | - Julian F R Paton
- Manaaki Manawa - the Centre for Heart Research, Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Grafton, Auckland, New Zealand
| | - Alain Nogaret
- Department of Physics, University of Bath, Claverton Down, Bath, UK.
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14
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Blömer LA, Giacalone E, Abbas F, Filipis L, Tegolo D, Migliore M, Canepari M. Kinetics and functional consequences of BK channels activation by N-type Ca 2+ channels in the dendrite of mouse neocortical layer-5 pyramidal neurons. Front Cell Neurosci 2024; 18:1353895. [PMID: 38419657 PMCID: PMC10899506 DOI: 10.3389/fncel.2024.1353895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 01/24/2024] [Indexed: 03/02/2024] Open
Abstract
The back-propagation of an action potential (AP) from the axon/soma to the dendrites plays a central role in dendritic integration. This process involves an intricate orchestration of various ion channels, but a comprehensive understanding of the contribution of each channel type remains elusive. In this study, we leverage ultrafast membrane potential recordings (Vm) and Ca2+ imaging techniques to shed light on the involvement of N-type voltage-gated Ca2+ channels (VGCCs) in layer-5 neocortical pyramidal neurons' apical dendrites. We found a selective interaction between N-type VGCCs and large-conductance Ca2+-activated K+ channels (BK CAKCs). Remarkably, we observe that BK CAKCs are activated within a mere 500 μs after the AP peak, preceding the peak of the Ca2+ current triggered by the AP. Consequently, when N-type VGCCs are inhibited, the early broadening of the AP shape amplifies the activity of other VGCCs, leading to an augmented total Ca2+ influx. A NEURON model, constructed to replicate and support these experimental results, reveals the critical coupling between N-type and BK channels. This study not only redefines the conventional role of N-type VGCCs as primarily involved in presynaptic neurotransmitter release but also establishes their distinct and essential function as activators of BK CAKCs in neuronal dendrites. Furthermore, our results provide original functional validation of a physical interaction between Ca2+ and K+ channels, elucidated through ultrafast kinetic reconstruction. This insight enhances our understanding of the intricate mechanisms governing neuronal signaling and may have far-reaching implications in the field.
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Affiliation(s)
- Laila Ananda Blömer
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
| | - Elisabetta Giacalone
- Institute of Biophysics, National Research Council, Palermo, Italy
- Dipartimento Matematica e Informatica, Universitá degli Studi di Palermo, Palermo, Italy
| | - Fatima Abbas
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
| | - Luiza Filipis
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
| | - Domenico Tegolo
- Dipartimento Matematica e Informatica, Universitá degli Studi di Palermo, Palermo, Italy
| | - Michele Migliore
- Institute of Biophysics, National Research Council, Palermo, Italy
| | - Marco Canepari
- LIPhy, CNRS, Université Grenoble Alpes, Grenoble, France
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France
- Institut National de la Santé et Recherche Médicale, Paris, France
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15
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Yamanouchi D, Kasuya G, Nakajo K, Kise Y, Nureki O. Dual allosteric modulation of voltage and calcium sensitivities of the Slo1-LRRC channel complex. Mol Cell 2023; 83:4555-4569.e4. [PMID: 38035882 DOI: 10.1016/j.molcel.2023.11.005] [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: 10/02/2022] [Revised: 09/15/2023] [Accepted: 11/06/2023] [Indexed: 12/02/2023]
Abstract
Modulation of large conductance intracellular ligand-activated potassium (BK) channel family (Slo1-3) by auxiliary subunits allows diverse physiological functions in excitable and non-excitable cells. Cryoelectron microscopy (cryo-EM) structures of voltage-gated potassium (Kv) channel complexes have provided insights into how voltage sensitivity is modulated by auxiliary subunits. However, the modulation mechanisms of BK channels, particularly as ligand-activated ion channels, remain unknown. Slo1 is a Ca2+-activated and voltage-gated BK channel and is expressed in neurons, muscle cells, and epithelial cells. Using cryo-EM and electrophysiology, we show that the LRRC26-γ1 subunit modulates not only voltage but also Ca2+ sensitivity of Homo sapiens Slo1. LRRC26 stabilizes the active conformation of voltage-senor domains of Slo1 by an extracellularly S4-locking mechanism. Furthermore, it also stabilizes the active conformation of Ca2+-sensor domains of Slo1 intracellularly, which is functionally equivalent to intracellular Ca2+ in the activation of Slo1. Such a dual allosteric modulatory mechanism may be general in regulating the intracellular ligand-activated BK channel complexes.
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Affiliation(s)
- Daichi Yamanouchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Go Kasuya
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan.
| | - Koichi Nakajo
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan
| | - Yoshiaki Kise
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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16
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Kallure GS, Pal K, Zhou Y, Lingle CJ, Chowdhury S. High-resolution structures illuminate key principles underlying voltage and LRRC26 regulation of Slo1 channels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.20.572542. [PMID: 38187713 PMCID: PMC10769243 DOI: 10.1101/2023.12.20.572542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Multi-modal regulation of Slo1 channels by membrane voltage, intracellular calcium, and auxiliary subunits enables its pleiotropic physiological functions. Our understanding of how voltage impacts Slo1 conformational dynamics and the mechanisms by which auxiliary subunits, particularly of the LRRC (Leucine Rich Repeat containing) family of proteins, modulate its voltage gating remain unresolved. Here, we used single particle cryo-electron microscopy to determine structures of human Slo1 mutants which functionally stabilize the closed pore (F315A) or the activated voltage-sensor (R207A). Our structures, obtained under calcium-free conditions, reveal that a key step in voltage-sensing by Slo1 involves a rotameric flip of the voltage-sensing charges (R210 and R213) moving them by ∼6 Å across a hydrophobic gasket. Next we obtained reconstructions of a complex of human Slo1 with the human LRRC26 (γ1) subunit in absence of calcium. Together with extensive biochemical tests, we show that the extracellular domains of γ1 form a ring of interlocked dominos that stabilizes the quaternary assembly of the complex and biases Slo1:γ1 assembly towards high stoichiometric complexes. The transmembrane helix of γ1 is kinked and tightly packed against the Slo1 voltage-sensor. We hypothesize that γ1 subunits exert relatively small effects on early steps in voltage-gating but structurally stabilize non-S4 helices of Slo1 voltage-sensor which energetically facilitate conformational rearrangements that occur late in voltage stimulated transitions.
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17
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North KC, Shaw AA, Bukiya AN, Dopico AM. Progesterone activation of β 1-containing BK channels involves two binding sites. Nat Commun 2023; 14:7248. [PMID: 37945687 PMCID: PMC10636063 DOI: 10.1038/s41467-023-42827-w] [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: 11/18/2022] [Accepted: 10/23/2023] [Indexed: 11/12/2023] Open
Abstract
Progesterone (≥1 µM) is used in recovery of cerebral ischemia, an effect likely contributed to by cerebrovascular dilation. The targets of this progesterone action are unknown. We report that micromolar (µM) progesterone activates mouse cerebrovascular myocyte BK channels; this action is lost in β1-/- mice myocytes and in lipid bilayers containing BK α subunit homomeric channels but sustained on β1/β4-containing heteromers. Progesterone binds to both regulatory subunits, involving two steroid binding sites conserved in β1-β4: high-affinity (sub-µM), which involves Trp87 in β1 loop, and low-affinity (µM) defined by TM1 Tyr32 and TM2 Trp163. Thus progesterone, but not its oxime, bridges TM1-TM2. Mutation of the high-affinity site blunts channel activation by progesterone underscoring a permissive role of the high-affinity site: progesterone binding to this site enables steroid binding at the low-affinity site, which activates the channel. In support of our model, cerebrovascular dilation evoked by μM progesterone is lost by mutating Tyr32 or Trp163 in β1 whereas these mutations do not affect alcohol-induced cerebrovascular constriction. Furthermore, this alcohol action is effectively counteracted both in vitro and in vivo by progesterone but not by its oxime.
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Affiliation(s)
- Kelsey C North
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, 38103, USA
| | - Andrew A Shaw
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, 38103, 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
| | - 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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18
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Figueiredo IAD, Ferreira SRD, Fernandes JM, Silva BA, Vasconcelos LHC, Cavalcante FA. A review of the pathophysiology and the role of ion channels on bronchial asthma. Front Pharmacol 2023; 14:1236550. [PMID: 37841931 PMCID: PMC10568497 DOI: 10.3389/fphar.2023.1236550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 09/08/2023] [Indexed: 10/17/2023] Open
Abstract
Asthma is one of the main non-communicable chronic diseases and affects a huge portion of the population. It is a multifactorial disease, classified into several phenotypes, being the allergic the most frequent. The pathophysiological mechanism of asthma involves a Th2-type immune response, with high concentrations of allergen-specific immunoglobulin E, eosinophilia, hyperreactivity and airway remodeling. These mechanisms are orchestrated by intracellular signaling from effector cells, such as lymphocytes and eosinophils. Ion channels play a fundamental role in maintaining the inflammatory response on asthma. In particular, transient receptor potential (TRP), stock-operated Ca2+ channels (SOCs), Ca2+-activated K+ channels (IKCa and BKCa), calcium-activated chloride channel (TMEM16A), cystic fibrosis transmembrane conductance regulator (CFTR), piezo-type mechanosensitive ion channel component 1 (PIEZO1) and purinergic P2X receptor (P2X). The recognition of the participation of these channels in the pathological process of asthma is important, as they become pharmacological targets for the discovery of new drugs and/or pharmacological tools that effectively help the pharmacotherapeutic follow-up of this disease, as well as the more specific mechanisms involved in worsening asthma.
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Affiliation(s)
- Indyra Alencar Duarte Figueiredo
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
| | - Sarah Rebeca Dantas Ferreira
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
| | - Jayne Muniz Fernandes
- Graduação em Farmácia, Departamento de Ciências Farmacêuticas, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
| | - Bagnólia Araújo da Silva
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
- Departamento de Ciências Farmacêuticas, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
| | - Luiz Henrique César Vasconcelos
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
- Departamento de Fisiologia e Patologia, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
| | - Fabiana de Andrade Cavalcante
- Programa de Pós-graduação em Produtos Naturais e Sintéticos Bioativos, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
- Departamento de Fisiologia e Patologia, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Paraíba, Brazil
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19
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Chen G, Li Q, Webb TI, Hollywood MA, Yan J. BK channel modulation by positively charged peptides and auxiliary γ subunits mediated by the Ca2+-bowl site. J Gen Physiol 2023; 155:e202213237. [PMID: 37130264 PMCID: PMC10163825 DOI: 10.1085/jgp.202213237] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 01/12/2023] [Accepted: 04/13/2023] [Indexed: 05/04/2023] Open
Abstract
The large-conductance, Ca2+-, and voltage-activated K+ (BK) channel consists of the pore-forming α (BKα) subunit and regulatory β and γ subunits. The γ1-3 subunits facilitate BK channel activation by shifting the voltage-dependence of channel activation toward the hyperpolarization direction by about 50-150 mV in the absence of Ca2+. We previously found that the intracellular C-terminal positively charged regions of the γ subunits play important roles in BK channel modulation. In this study, we found that the intracellular C-terminal region of BKα is indispensable in BK channel modulation by the γ1 subunit. Notably, synthetic peptide mimics of the γ1-3 subunits' C-terminal positively charged regions caused 30-50 mV shifts in BKα channel voltage-gating toward the hyperpolarization direction. The cationic cell-penetrating HIV-1 Tat peptide exerted a similar BK channel-activating effect. The BK channel-activating effects of the synthetic peptides were reduced in the presence of Ca2+ and markedly ablated by both charge neutralization of the Ca2+-bowl site and high ionic strength, suggesting the involvement of electrostatic interactions. The efficacy of the γ subunits in BK channel modulation was reduced by charge neutralization of the Ca2+-bowl site. However, BK channel modulation by the γ1 subunit was little affected by high ionic strength and the positively charged peptide remained effective in BK channel modulation in the presence of the γ1 subunit. These findings identify positively charged peptides as BK channel modulators and reveal a role for the Ca2+-bowl site in BK channel modulation by positively charged peptides and the C-terminal positively charged regions of auxiliary γ subunits.
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Affiliation(s)
- Guanxing Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Qin Li
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Timothy I. Webb
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mark A. Hollywood
- The Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Neuroscience and Biochemistry and Cell Biology Graduate Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, TX, USA
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20
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Mysiewicz SC, Hawks SM, Bukiya AN, Dopico AM. Differential Functional Contribution of BK Channel Subunits to Aldosterone-Induced Channel Activation in Vascular Smooth Muscle and Eventual Cerebral Artery Dilation. Int J Mol Sci 2023; 24:ijms24108704. [PMID: 37240049 DOI: 10.3390/ijms24108704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/03/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Calcium/voltage-activated potassium channels (BK) control smooth muscle (SM) tone and cerebral artery diameter. They include channel-forming α and regulatory β1 subunits, the latter being highly expressed in SM. Both subunits participate in steroid-induced modification of BK activity: β1 provides recognition for estradiol and cholanes, resulting in BK potentiation, whereas α suffices for BK inhibition by cholesterol or pregnenolone. Aldosterone can modify cerebral artery function independently of its effects outside the brain, yet BK involvement in aldosterone's cerebrovascular action and identification of channel subunits, possibly involved in steroid action, remains uninvestigated. Using microscale thermophoresis, we demonstrated that each subunit type presents two recognition sites for aldosterone: at 0.3 and ≥10 µM for α and at 0.3-1 µM and ≥100 µM for β1. Next, we probed aldosterone on SM BK activity and diameter of middle cerebral artery (MCA) isolated from β1-/- vs. wt mice. Data showed that β1 leftward-shifted aldosterone-induced BK activation, rendering EC50~3 μM and ECMAX ≥ 10 μM, at which BK activity increased by 20%. At similar concentrations, aldosterone mildly yet significantly dilated MCA independently of circulating and endothelial factors. Lastly, aldosterone-induced MCA dilation was lost in β1-/- mice. Therefore, β1 enables BK activation and MCA dilation by low µM aldosterone.
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Affiliation(s)
- Steven C Mysiewicz
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103, USA
| | - Sydney M Hawks
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN 38103, 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
| | - 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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21
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Takács R, Kovács P, Ebeid RA, Almássy J, Fodor J, Ducza L, Barrett-Jolley R, Lewis R, Matta C. Ca2+-Activated K+ Channels in Progenitor Cells of Musculoskeletal Tissues: A Narrative Review. Int J Mol Sci 2023; 24:ijms24076796. [PMID: 37047767 PMCID: PMC10095002 DOI: 10.3390/ijms24076796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/01/2023] [Accepted: 04/04/2023] [Indexed: 04/08/2023] Open
Abstract
Musculoskeletal disorders represent one of the main causes of disability worldwide, and their prevalence is predicted to increase in the coming decades. Stem cell therapy may be a promising option for the treatment of some of the musculoskeletal diseases. Although significant progress has been made in musculoskeletal stem cell research, osteoarthritis, the most-common musculoskeletal disorder, still lacks curative treatment. To fine-tune stem-cell-based therapy, it is necessary to focus on the underlying biological mechanisms. Ion channels and the bioelectric signals they generate control the proliferation, differentiation, and migration of musculoskeletal progenitor cells. Calcium- and voltage-activated potassium (KCa) channels are key players in cell physiology in cells of the musculoskeletal system. This review article focused on the big conductance (BK) KCa channels. The regulatory function of BK channels requires interactions with diverse sets of proteins that have different functions in tissue-resident stem cells. In this narrative review article, we discuss the main ion channels of musculoskeletal stem cells, with a focus on calcium-dependent potassium channels, especially on the large conductance BK channel. We review their expression and function in progenitor cell proliferation, differentiation, and migration and highlight gaps in current knowledge on their involvement in musculoskeletal diseases.
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Affiliation(s)
- Roland Takács
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Patrik Kovács
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Rana Abdelsattar Ebeid
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, Semmelweis University, H-1428 Budapest, Hungary
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - László Ducza
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Richard Barrett-Jolley
- Department of Musculoskeletal Biology, Faculty of Health and Life Sciences, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Rebecca Lewis
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Csaba Matta
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
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22
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Nguyen NH, Brodsky JL. The cellular pathways that maintain the quality control and transport of diverse potassium channels. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2023; 1866:194908. [PMID: 36638864 PMCID: PMC9908860 DOI: 10.1016/j.bbagrm.2023.194908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/20/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
Potassium channels are multi-subunit transmembrane proteins that permit the selective passage of potassium and play fundamental roles in physiological processes, such as action potentials in the nervous system and organismal salt and water homeostasis, which is mediated by the kidney. Like all ion channels, newly translated potassium channels enter the endoplasmic reticulum (ER) and undergo the error-prone process of acquiring post-translational modifications, folding into their native conformations, assembling with other subunits, and trafficking through the secretory pathway to reach their final destinations, most commonly the plasma membrane. Disruptions in these processes can result in detrimental consequences, including various human diseases. Thus, multiple quality control checkpoints evolved to guide potassium channels through the secretory pathway and clear potentially toxic, aggregation-prone misfolded species. We will summarize current knowledge on the mechanisms underlying potassium channel quality control in the secretory pathway, highlight diseases associated with channel misfolding, and suggest potential therapeutic routes.
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Affiliation(s)
- Nga H Nguyen
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA.
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Potassium channelopathies associated with epilepsy-related syndromes and directions for therapeutic intervention. Biochem Pharmacol 2023; 208:115413. [PMID: 36646291 DOI: 10.1016/j.bcp.2023.115413] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
A number of mutations to members of several CNS potassium (K) channel families have been identified which result in rare forms of neonatal onset epilepsy, or syndromes of which one prominent characteristic is a form of epilepsy. Benign Familial Neonatal Convulsions or Seizures (BFNC or BFNS), also referred to as Self-Limited Familial Neonatal Epilepsy (SeLNE), results from mutations in 2 members of the KV7 family (KCNQ) of K channels; while generally self-resolving by about 15 weeks of age, these mutations significantly increase the probability of generalized seizure disorders in the adult, in some cases they result in more severe developmental syndromes. Epilepsy of Infancy with Migrating Focal Seizures (EIMSF), or Migrating Partial Seizures of Infancy (MMPSI), is a rare severe form of epilepsy linked primarily to gain of function mutations in a member of the sodium-dependent K channel family, KCNT1 or SLACK. Finally, KCNMA1 channelopathies, including Liang-Wang syndrome (LIWAS), are rare combinations of neurological symptoms including seizure, movement abnormalities, delayed development and intellectual disabilities, with Liang-Wang syndrome an extremely serious polymalformative syndrome with a number of neurological sequelae including epilepsy. These are caused by mutations in the pore-forming subunit of the large-conductance calcium-activated K channel (BK channel) KCNMA1. The identification of these rare but significant channelopathies has resulted in a resurgence of interest in their treatment by direct pharmacological or genetic modulation. We will briefly review the genetics, biophysics and pharmacology of these K channels, their linkage with the 3 syndromes described above, and efforts to more effectively target these syndromes.
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Ca 2+-Activated K + Channels and the Regulation of the Uteroplacental Circulation. Int J Mol Sci 2023; 24:ijms24021349. [PMID: 36674858 PMCID: PMC9867535 DOI: 10.3390/ijms24021349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/13/2023] Open
Abstract
Adequate uteroplacental blood supply is essential for the development and growth of the placenta and fetus during pregnancy. Aberrant uteroplacental perfusion is associated with pregnancy complications such as preeclampsia, fetal growth restriction (FGR), and gestational diabetes. The regulation of uteroplacental blood flow is thus vital to the well-being of the mother and fetus. Ca2+-activated K+ (KCa) channels of small, intermediate, and large conductance participate in setting and regulating the resting membrane potential of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) and play a critical role in controlling vascular tone and blood pressure. KCa channels are important mediators of estrogen/pregnancy-induced adaptive changes in the uteroplacental circulation. Activation of the channels hyperpolarizes uteroplacental VSMCs/ECs, leading to attenuated vascular tone, blunted vasopressor responses, and increased uteroplacental blood flow. However, the regulation of uteroplacental vascular function by KCa channels is compromised in pregnancy complications. This review intends to provide a comprehensive overview of roles of KCa channels in the regulation of the uteroplacental circulation under physiological and pathophysiological conditions.
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Wang ZW, Trussell LO, Vedantham K. Regulation of Neurotransmitter Release by K + Channels. ADVANCES IN NEUROBIOLOGY 2023; 33:305-331. [PMID: 37615872 DOI: 10.1007/978-3-031-34229-5_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
K+ channels play potent roles in the process of neurotransmitter release by influencing the action potential waveform and modulating neuronal excitability and release probability. These diverse effects of K+ channel activation are ensured by the wide variety of K+ channel genes and their differential expression in different cell types. Accordingly, a variety of K+ channels have been implicated in regulating neurotransmitter release, including the Ca2+- and voltage-gated K+ channel Slo1 (also known as BK channel), voltage-gated K+ channels of the Kv3 (Shaw-type), Kv1 (Shaker-type), and Kv7 (KCNQ) families, G-protein-gated inwardly rectifying K+ (GIRK) channels, and SLO-2 (a Ca2+-. Cl-, and voltage-gated K+ channel in C. elegans). These channels vary in their expression patterns, subcellular localization, and biophysical properties. Their roles in neurotransmitter release may also vary depending on the synapse and physiological or experimental conditions. This chapter summarizes key findings about the roles of K+ channels in regulating neurotransmitter release.
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Affiliation(s)
- Zhao-Wen Wang
- Department of Neuroscience, University of Connecticut School of Medicine, Farmington, CT, USA.
| | - Laurence O Trussell
- Oregon Hearing Research Center & Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Kiranmayi Vedantham
- Department of Neuroscience, University of Connecticut School of Medicine, Farmington, CT, USA
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26
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Vaithianathan T, Schneider EH, Bukiya AN, Dopico AM. Cholesterol and PIP 2 Modulation of BK Ca Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:217-243. [PMID: 36988883 PMCID: PMC10683925 DOI: 10.1007/978-3-031-21547-6_8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Ca2+/voltage-gated, large conductance K+ channels (BKCa) are formed by homotetrameric association of α (slo1) subunits. Their activity, however, is suited to tissue-specific physiology largely due to their association with regulatory subunits (β and γ types), chaperone proteins, localized signaling, and the channel's lipid microenvironment. PIP2 and cholesterol can modulate BKCa activity independently of downstream signaling, yet activating Ca2+i levels and regulatory subunits control ligand action. At physiological Ca2+i and voltages, cholesterol and PIP2 reduce and increase slo1 channel activity, respectively. Moreover, slo1 proteins provide sites that seem to recognize cholesterol and PIP2: seven CRAC motifs in the slo1 cytosolic tail and a string of positively charged residues (Arg329, Lys330, Lys331) immediately after S6, respectively. A model that could explain the modulation of BKCa activity by cholesterol and/or PIP2 is hypothesized. The roles of additional sites, whether in slo1 or BKCa regulatory subunits, for PIP2 and/or cholesterol to modulate BKCa function are also discussed.
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Affiliation(s)
- Thirumalini Vaithianathan
- Department Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Elizabeth H Schneider
- Department Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Anna N Bukiya
- Department Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Alex M Dopico
- Department Pharmacology, Addiction Science, and Toxicology, College of Medicine, The University of Tennessee Health Science Center, Memphis, TN, USA.
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27
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Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
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28
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Feher A, Pethő Z, Szanto TG, Klekner Á, Tajti G, Batta G, Hortobágyi T, Varga Z, Schwab A, Panyi G. Mapping the functional expression of auxiliary subunits of K Ca1.1 in glioblastoma. Sci Rep 2022; 12:22023. [PMID: 36539587 PMCID: PMC9768140 DOI: 10.1038/s41598-022-26196-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
Glioblastoma (GBM) is the most aggressive glial tumor, where ion channels, including KCa1.1, are candidates for new therapeutic options. Since the auxiliary subunits linked to KCa1.1 in GBM are largely unknown we used electrophysiology combined with pharmacology and gene silencing to address the functional expression of KCa1.1/β subunits complexes in both primary tumor cells and in the glioblastoma cell line U-87 MG. The pattern of the sensitivity (activation/inhibition) of the whole-cell currents to paxilline, lithocholic acid, arachidonic acid, and iberiotoxin; the presence of inactivation of the whole-cell current along with the loss of the outward rectification upon exposure to the reducing agent DTT collectively argue that KCa1.1/β3 complex is expressed in U-87 MG. Similar results were found using human primary glioblastoma cells isolated from patient samples. Silencing the β3 subunit expression inhibited carbachol-induced Ca2+ transients in U-87 MG thereby indicating the role of the KCa1.1/β3 in the Ca2+ signaling of glioblastoma cells. Functional expression of the KCa1.1/β3 complex, on the other hand, lacks cell cycle dependence. We suggest that the KCa1.1/β3 complex may have diagnostic and therapeutic potential in glioblastoma in the future.
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Affiliation(s)
- Adam Feher
- Department of Biophysics and Cell Biology, Faculty of Medicine, University Debrecen, Debrecen, Hungary
| | - Zoltán Pethő
- Department of Biophysics and Cell Biology, Faculty of Medicine, University Debrecen, Debrecen, Hungary
- Institute of Physiology II, University Münster, Münster, Germany
| | - Tibor G Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, University Debrecen, Debrecen, Hungary
| | - Álmos Klekner
- Department of Neurosurgery, Faculty of Medicine, University Debrecen, Debrecen, Hungary
| | - Gabor Tajti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University Debrecen, Debrecen, Hungary
| | - Gyula Batta
- Department of Genetics and Applied Microbiology, University Debrecen, Debrecen, Hungary
| | - Tibor Hortobágyi
- Faculty of Medicine, Institute of Pathology, University of Szeged, Szeged, Hungary
- ELKH-DE Cerebrovascular and Neurodegenerative Research Group, Department of Neurology, Faculty of Medicine, University Debrecen, Debrecen, Hungary
| | - Zoltan Varga
- Department of Biophysics and Cell Biology, Faculty of Medicine, University Debrecen, Debrecen, Hungary
| | - Albrecht Schwab
- Institute of Physiology II, University Münster, Münster, Germany
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University Debrecen, Debrecen, Hungary.
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29
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Kassa M, Bradley J, Jalil A, Llano I. KCa1.1 channels contribute to optogenetically driven post-stimulation silencing in cerebellar molecular layer interneurons. J Gen Physiol 2022; 155:213661. [PMID: 36326690 PMCID: PMC9640226 DOI: 10.1085/jgp.202113004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 07/06/2022] [Accepted: 10/07/2022] [Indexed: 11/06/2022] Open
Abstract
Using cell-attached recordings from molecular layer interneurons (MLI) of the cerebellar cortex of adult mice expressing channel rhodopsin 2, we show that wide-field optical activation induces an increase in firing rate during illumination and a firing pause when the illumination ends (post-stimulation silencing; PSS). Significant spike rate changes with respect to basal firing rate were observed for optical activations lasting 200 ms and 1 s as well as for 1 s long trains of 10 ms pulses at 50 Hz. For all conditions, the net effect of optical activation on the integrated spike rate is significantly reduced because of PSS. Three lines of evidence indicate that this PSS is due to intrinsic factors. Firstly, PSS is induced when the optical stimulation is restricted to a single MLI using a 405-nm laser delivering a diffraction-limited spot at the focal plane. Secondly, PSS is not affected by block of GABA-A or GABA-B receptors, ruling out synaptic interactions amongst MLIs. Thirdly, PSS is mimicked in whole-cell recording experiments by step depolarizations under current clamp. Activation of Ca-dependent K channels during the spike trains appears as a likely candidate to underlie PSS. Using immunocytochemistry, we find that one such channel type, KCa1.1, is present in the somato-dendritic and axonal compartments of MLIs. In cell-attached recordings, charybdotoxin and iberiotoxin significantly reduce the optically induced PSS, while TRAM-34 does not affect it, suggesting that KCa1.1 channels, but not KCa3.1 channels, contribute to PSS.
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Affiliation(s)
- Merouann Kassa
- Université Paris Cité, Centre National de la Recherche Scientifique, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Jonathan Bradley
- Institut de Biologie de l’Ecole Normale Superieure (IBENS), Ecole Normale Superieure, Centre National de la Recherche Scientifique, INSERM, Paris Sciences et Lettres Research University, Paris, France
| | - Abdelali Jalil
- Université Paris Cité, Centre National de la Recherche Scientifique, Saints-Pères Paris Institute for the Neurosciences, Paris, France
| | - Isabel Llano
- Université Paris Cité, Centre National de la Recherche Scientifique, Saints-Pères Paris Institute for the Neurosciences, Paris, France
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30
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Blackwell JA, Silva JF, Louis EM, Savu A, Largent-Milnes TM, Brooks HL, Pires PW. Cerebral arteriolar and neurovascular dysfunction after chemically induced menopause in mice. Am J Physiol Heart Circ Physiol 2022; 323:H845-H860. [PMID: 36149767 PMCID: PMC9602916 DOI: 10.1152/ajpheart.00276.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/20/2022] [Accepted: 09/20/2022] [Indexed: 12/14/2022]
Abstract
Cognitive decline is linked to decreased cerebral blood flow, particularly in women after menopause. Impaired cerebrovascular function precedes the onset of dementia, possibly because of reduced functional dilation in parenchymal arterioles. These vessels are bottlenecks of the cerebral microcirculation, and dysfunction can limit functional hyperemia in the brain. Large-conductance Ca2+-activated K+ channels (BKCa) are the final effectors of several pathways responsible for functional hyperemia, and their expression is modulated by estrogen. However, it remains unknown whether BKCa function is altered in cerebral parenchymal arterioles after menopause. Using a chemically induced model of menopause, the 4-vinylcyclohexene diepoxide (VCD) model, which depletes follicles while maintaining intact ovaries, we hypothesized that menopause would be associated with reduced functional vasodilatory responses in cerebral parenchymal arterioles of wild-type mice via reduced BKCa function. Using pressure myography of isolated parenchymal arterioles, we observed that menopause (Meno) induced a significant increase in spontaneous myogenic tone. Endothelial function, assessed as nitric oxide production and dilation after cholinergic stimulation or endothelium-dependent hyperpolarization pathways, was unaffected by Meno. BKCa function was significantly impaired in Meno compared with control, without changes in voltage-gated K+ channel activity. Cerebral functional hyperemia, measured by laser-speckle contrast imaging during whisker stimulation, was significantly blunted in Meno mice, without detectable changes in basal perfusion. However, behavioral testing identified no change in cognition. These findings suggest that menopause induces cerebral microvascular and neurovascular deficits.NEW & NOTEWORTHY Cerebral parenchymal arterioles from menopause mice showed increased myogenic tone. We identified an impairment in smooth muscle cell BKCa channel activity, without a reduction in endothelium-dependent dilation or nitric oxide production. Microvascular dysfunction was associated with a reduction in neurovascular responses after somatosensory stimulation. Despite the neurovascular impairment, cognitive abilities were maintained in menopausal mice.
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Affiliation(s)
- Jade A Blackwell
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Josiane F Silva
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Emma M Louis
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Andrea Savu
- Department of Physiology, University of Arizona, Tucson, Arizona
| | - Tally M Largent-Milnes
- Department of Pharmacology, University of Arizona, Tucson, Arizona
- Bio5 Institute, University of Arizona, Tucson, Arizona
| | - Heddwen L Brooks
- Department of Physiology, University of Arizona, Tucson, Arizona
- Bio5 Institute, University of Arizona, Tucson, Arizona
- Sarver Heart Center, University of Arizona, Tucson, Arizona
| | - Paulo W Pires
- Department of Physiology, University of Arizona, Tucson, Arizona
- Bio5 Institute, University of Arizona, Tucson, Arizona
- Sarver Heart Center, University of Arizona, Tucson, Arizona
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31
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Daghbouche-Rubio N, López-López JR, Pérez-García MT, Cidad P. Vascular smooth muscle ion channels in essential hypertension. Front Physiol 2022; 13:1016175. [PMID: 36213221 PMCID: PMC9540222 DOI: 10.3389/fphys.2022.1016175] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 08/31/2022] [Indexed: 11/13/2022] Open
Abstract
Hypertension is a highly prevalent chronic disease and the major risk factor for cardiovascular diseases, the leading cause of death worldwide. Hypertension is characterized by an increased vascular tone determined by the contractile state of vascular smooth muscle cells that depends on intracellular calcium levels. The interplay of ion channels determine VSMCs membrane potential and thus intracellular calcium that controls the degree of contraction, vascular tone and blood pressure. Changes in ion channels expression and function have been linked to hypertension, but the mechanisms and molecular entities involved are not completely clear. Furthermore, the literature shows discrepancies regarding the contribution of different ion channels to hypertension probably due to differences both in the vascular preparation and in the model of hypertension employed. Animal models are essential to study this multifactorial disease but it is also critical to know their characteristics to interpret properly the results obtained. In this review we summarize previous studies, using the hypertensive mouse (BPH) and its normotensive control (BPN), focused on the identified changes in the expression and function of different families of ion channels. We will focus on L-type voltage-dependent Ca2+ channels (Cav1.2), canonical transient receptor potential channels and four different classes of K+ channels: voltage-activated (Kv), large conductance Ca2+-activated (BK), inward rectifiers (Kir) and ATP-sensitive (KATP) K+ channels. We will describe the role of these channels in hypertension and we will discuss the importance of integrating individual changes in a global context to understand the complex interplay of ion channels in hypertension.
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32
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Potassium Channels in the Uterine Vasculature: Role in Healthy and Complicated Pregnancies. Int J Mol Sci 2022; 23:ijms23169446. [PMID: 36012712 PMCID: PMC9409294 DOI: 10.3390/ijms23169446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/16/2022] [Accepted: 08/19/2022] [Indexed: 11/28/2022] Open
Abstract
A progressive increase in maternal uterine and placental blood flow must occur during pregnancy to sustain the development of the fetus. Changes in maternal vasculature enable an increased uterine blood flow, placental nutrient and oxygen exchange, and subsequent fetal development. K+ channels are important modulators of vascular function, promoting vasodilation, inducing cell proliferation, and regulating cell signaling. Different types of K+ channels, such as Ca2+-activated, ATP-sensitive, and voltage-gated, have been implicated in the adaptation of maternal vasculature during pregnancy. Conversely, K+ channel dysfunction has been associated with vascular-related complications of pregnancy, including intrauterine growth restriction and pre-eclampsia. In this article, we provide an updated and comprehensive literature review that highlights the relevance of K+ channels as regulators of uterine vascular reactivity and their potential as therapeutic targets.
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33
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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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34
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The function of BK channels extracted and purified within SMALPs. Biochem J 2022; 479:1609-1619. [PMID: 35851603 PMCID: PMC9444072 DOI: 10.1042/bcj20210628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 06/27/2022] [Accepted: 07/19/2022] [Indexed: 11/17/2022]
Abstract
Human BK channels are large voltage and Ca2+-activated K+ channels, involved in several important functions within the body. The core channel is a tetramer of α subunits, and its function is modulated by the presence of β and γ accessory subunits. BK channels composed of α subunits, as well as BK channels composed of α and β1 subunits, were successfully solubilised from HEK cells with styrene maleic acid (SMA) polymer and purified by nickel affinity chromatography. Native SMA–PAGE analysis of the purified proteins showed the α subunits were extracted as a tetramer. In the presence of β1 subunits, they were co-extracted with the α subunits as a heteromeric complex. Purified SMA lipid particles (SMALPs) containing BK channel could be inserted into planar lipid bilayers (PLB) and single channel currents recorded, showing a high conductance (≈260 pS), as expected. The open probability was increased in the presence of co-purified β1 subunits. However, voltage-dependent gating of the channel was restricted. In conclusion, we have demonstrated that SMA can be used to effectively extract and purify large, complex, human ion channels, from low expressing sources. That these large channels can be incorporated into PLB from SMALPs and display voltage-dependent channel activity. However, the SMA appears to reduce the voltage dependent gating of the channels.
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35
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Discovery and characterization of a potent activator of the BK Ca channel that relives overactive bladder syndrome in rats. Eur J Pharmacol 2022; 927:175055. [PMID: 35644420 DOI: 10.1016/j.ejphar.2022.175055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 05/13/2022] [Accepted: 05/19/2022] [Indexed: 11/21/2022]
Abstract
The large-conductance Ca2+-activated K+ channel (BKCa channel) is involved in repolarizing the membrane potential and has a variety of cellular functions. The BKCa channel is highly expressed in bladder smooth muscle and mediates muscle relaxation. Compounds that activate the BKCa channel have therapeutic potential against pathological symptoms associated with the overactivity of bladder smooth muscle. In this regard, we screened a chemical library of 9938 compounds to identify novel BKCa channel activators. A cell-based fluorescence assay identified a structural family of compounds containing a common tricyclic quinazoline ring that activated the BKCa channel. The most potent compound TTQC-1 (7-bromo-N-(3-methylphenyl)-5-oxo-1-thioxo-4,5-dihydro[1,3]thiazolo[3,4-a]quinazoline-3-carboxamide) directly and reversibly activated the macroscopic current of BKCa channels expressed in Xenopus oocytes from both sides of the cellular membrane. TTQC-1 increased the maximum conductance and shifted the half activation voltage to the left. The apparent half-maximal effective concentration and dissociation constant were 2.8 μM and 7.95 μM, respectively. TTQC-1 delayed the kinetics of channel deactivation without affecting channel activation. The activation effects were observed over a wide range of intracellular Ca2+ concentrations and dependent on the co-expression of β1 and β4 auxiliary subunits, which are highly expressed in urinary bladder. In the isolated smooth muscle cells of rat urinary bladder, TTQC-1 increased the K+ currents which can be blocked by iberiotoxin. Finally, oral administration of TTQC-1 to hypertensive rats decreased the urination frequency. Therefore, TTQC-1 is a BKCa channel activator with a novel structure that is a potential therapeutic candidate for BKCa channel-related diseases, such as overactive bladder syndrome.
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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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Gonzalez-Perez V, Zhou Y, Ciorba MA, Lingle CJ. The LRRC family of BK channel regulatory subunits: potential roles in health and disease. J Physiol 2022; 600:1357-1371. [PMID: 35014034 PMCID: PMC8930516 DOI: 10.1113/jp281952] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/04/2022] [Indexed: 11/08/2022] Open
Abstract
Large conductance K+ channels, termed BK channels, regulate a variety of cellular and physiological functions. Although universally activated by changes in voltage or [Ca2+ ]i , the threshold for BK channel activation varies among loci of expression, often arising from cell-specific regulatory subunits including a family of leucine rich repeat-containing (LRRC) γ subunits (LRRC26, LRRC52, LRRC55 and LRRC38). The 'founding' member of this family, LRRC26, was originally identified as a tumour suppressor in various cancers. An LRRC26 knockout (KO) mouse model recently revealed that LRRC26 is also highly expressed in secretory epithelial cells and partners with BK channels in the salivary gland and colonic goblet cells to promote sustained K+ fluxes likely essential for normal secretory function. To accomplish this, LRRC26 negatively shifts the range of BK channel activation such that channels contribute to K+ flux near typical epithelial cell resting conditions. In colon, the absence of LRRC26 increases vulnerability to colitis. LRRC26-containing BK channels are also likely important regulators of epithelial function in other loci, including airways, female reproductive tract and mammary gland. Based on an LRRC52 KO mouse model, LRRC52 regulation of large conductance K+ channels plays a role both in sperm function and in cochlear inner hair cells. Although our understanding of LRRC-containing BK channels remains rudimentary, KO mouse models may help define other organs in which LRRC-containing channels support normal function. A key topic for future work concerns identification of endogenous mechanisms, whether post-translational or via gene regulation, that may impact LRRC-dependent pathologies.
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Affiliation(s)
- Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO, USA
| | - Yu Zhou
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO, USA
| | - Matthew A Ciorba
- Department of Internal Medicine, Division of Gastroenterology, Washington University School of Medicine, St Louis, MO, USA
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO, USA
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Chen G, Li Q, Yan J. The leucine-rich repeat domains of BK channel auxiliary γ subunits regulate their expression, trafficking, and channel-modulation functions. J Biol Chem 2022; 298:101664. [PMID: 35104503 PMCID: PMC8892010 DOI: 10.1016/j.jbc.2022.101664] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/16/2022] [Accepted: 01/26/2022] [Indexed: 11/25/2022] Open
Abstract
As high-conductance calcium- and voltage-dependent potassium channels, BK channels consist of pore-forming, voltage-, and Ca2+-sensing α and auxiliary subunits. The leucine-rich repeat (LRR) domain-containing auxiliary γ subunits potently modulate the voltage dependence of BK channel activation. Despite their dominant size in whole protein masses, the function of the LRR domain in BK channel γ subunits is unknown. We here investigated the function of these LRR domains in BK channel modulation by the auxiliary γ1-3 (LRRC26, LRRC52, and LRRC55) subunits. Using cell surface protein immunoprecipitation, we validated the predicted extracellular localization of the LRR domains. We then refined the structural models of mature proteins on the membrane via molecular dynamic simulations. By replacement of the LRR domain with extracellular regions or domains of non-LRR proteins, we found that the LRR domain is nonessential for the maximal channel-gating modulatory effect but is necessary for the all-or-none phenomenon of BK channel modulation by the γ1 subunit. Mutational and enzymatic blockade of N-glycosylation in the γ1-3 subunits resulted in a reduction or loss of BK channel modulation by γ subunits. Finally, by analyzing their expression in whole cells and on the plasma membrane, we found that blockade of N-glycosylation drastically reduced total expression of the γ2 subunit and the cell surface expression of the γ1 and γ3 subunits. We conclude that the LRR domains play key roles in the regulation of the expression, cell surface trafficking, and channel-modulation functions of the BK channel γ subunits.
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Affiliation(s)
- Guanxing Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Qin Li
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA; Graduate Programs of Neuroscience and Biochemistry and Cell Biology, The University of Texas MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, Texas, USA.
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Tikhonov DB, Zhorov BS. P-Loop Channels: Experimental Structures, and Physics-Based and Neural Networks-Based Models. MEMBRANES 2022; 12:membranes12020229. [PMID: 35207150 PMCID: PMC8876033 DOI: 10.3390/membranes12020229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/09/2022] [Accepted: 02/09/2022] [Indexed: 01/27/2023]
Abstract
The superfamily of P-loop channels includes potassium, sodium, and calcium channels, as well as TRP channels and ionotropic glutamate receptors. A rapidly increasing number of crystal and cryo-EM structures have revealed conserved and variable elements of the channel structures. Intriguing differences are seen in transmembrane helices of channels, which may include π-helical bulges. The bulges reorient residues in the helices and thus strongly affect their intersegment contacts and patterns of ligand-sensing residues. Comparison of the experimental structures suggests that some π-bulges are dynamic: they may appear and disappear upon channel gating and ligand binding. The AlphaFold2 models represent a recent breakthrough in the computational prediction of protein structures. We compared some crystal and cryo-EM structures of P-loop channels with respective AlphaFold2 models. Folding of the regions, which are resolved experimentally, is generally similar to that predicted in the AlphaFold2 models. The models also reproduce some subtle but significant differences between various P-loop channels. However, patterns of π-bulges do not necessarily coincide in the experimental and AlphaFold2 structures. Given the importance of dynamic π-bulges, further studies involving experimental and theoretical approaches are necessary to understand the cause of the discrepancy.
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Shah KR, Guan X, Yan J. Structural and Functional Coupling of Calcium-Activated BK Channels and Calcium-Permeable Channels Within Nanodomain Signaling Complexes. Front Physiol 2022; 12:796540. [PMID: 35095560 PMCID: PMC8795833 DOI: 10.3389/fphys.2021.796540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 12/28/2021] [Indexed: 11/13/2022] Open
Abstract
Biochemical and functional studies of ion channels have shown that many of these integral membrane proteins form macromolecular signaling complexes by physically associating with many other proteins. These macromolecular signaling complexes ensure specificity and proper rates of signal transduction. The large-conductance, Ca2+-activated K+ (BK) channel is dually activated by membrane depolarization and increases in intracellular free Ca2+ ([Ca2+]i). The activation of BK channels results in a large K+ efflux and, consequently, rapid membrane repolarization and closing of the voltage-dependent Ca2+-permeable channels to limit further increases in [Ca2+]i. Therefore, BK channel-mediated K+ signaling is a negative feedback regulator of both membrane potential and [Ca2+]i and plays important roles in many physiological processes and diseases. However, the BK channel formed by the pore-forming and voltage- and Ca2+-sensing α subunit alone requires high [Ca2+]i levels for channel activation under physiological voltage conditions. Thus, most native BK channels are believed to co-localize with Ca2+-permeable channels within nanodomains (a few tens of nanometers in distance) to detect high levels of [Ca2+]i around the open pores of Ca2+-permeable channels. Over the last two decades, advancement in research on the BK channel’s coupling with Ca2+-permeable channels including recent reports involving NMDA receptors demonstrate exemplary models of nanodomain structural and functional coupling among ion channels for efficient signal transduction and negative feedback regulation. We hereby review our current understanding regarding the structural and functional coupling of BK channels with different Ca2+-permeable channels.
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Affiliation(s)
- Kunal R. Shah
- Department of Anesthesiology & Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Xin Guan
- Department of Anesthesiology & Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Jiusheng Yan
- Department of Anesthesiology & Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
- Neuroscience Program, Graduate School of Biomedical Sciences, UT Health, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
- Biochemistry and Cell Biology Program, Graduate School of Biomedical Sciences, UT Health, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
- *Correspondence: Jiusheng Yan,
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Ochoa SV, Otero L, Aristizabal-Pachon AF, Hinostroza F, Carvacho I, Torres YP. Hypoxic Regulation of the Large-Conductance, Calcium and Voltage-Activated Potassium Channel, BK. Front Physiol 2022; 12:780206. [PMID: 35002762 PMCID: PMC8727448 DOI: 10.3389/fphys.2021.780206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/15/2021] [Indexed: 11/15/2022] Open
Abstract
Hypoxia is a condition characterized by a reduction of cellular oxygen levels derived from alterations in oxygen balance. Hypoxic events trigger changes in cell-signaling cascades, oxidative stress, activation of pro-inflammatory molecules, and growth factors, influencing the activity of various ion channel families and leading to diverse cardiovascular diseases such as myocardial infarction, ischemic stroke, and hypertension. The large-conductance, calcium and voltage-activated potassium channel (BK) has a central role in the mechanism of oxygen (O2) sensing and its activity has been related to the hypoxic response. BK channels are ubiquitously expressed, and they are composed by the pore-forming α subunit and the regulatory subunits β (β1–β4), γ (γ1–γ4), and LINGO1. The modification of biophysical properties of BK channels by β subunits underly a myriad of physiological function of these proteins. Hypoxia induces tissue-specific modifications of BK channel α and β subunits expression. Moreover, hypoxia modifies channel activation kinetics and voltage and/or calcium dependence. The reported effects on the BK channel properties are associated with events such as the increase of reactive oxygen species (ROS) production, increases of intracellular Calcium ([Ca2+]i), the regulation by Hypoxia-inducible factor 1α (HIF-1α), and the interaction with hemeproteins. Bronchial asthma, chronic obstructive pulmonary diseases (COPD), and obstructive sleep apnea (OSA), among others, can provoke hypoxia. Untreated OSA patients showed a decrease in BK-β1 subunit mRNA levels and high arterial tension. Treatment with continuous positive airway pressure (CPAP) upregulated β1 subunit mRNA level, decreased arterial pressures, and improved endothelial function coupled with a reduction in morbidity and mortality associated with OSA. These reports suggest that the BK channel has a role in the response involved in hypoxia-associated hypertension derived from OSA. Thus, this review aims to describe the mechanisms involved in the BK channel activation after a hypoxic stimulus and their relationship with disorders like OSA. A deep understanding of the molecular mechanism involved in hypoxic response may help in the therapeutic approaches to treat the pathological processes associated with diseases involving cellular hypoxia.
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Affiliation(s)
- Sara V Ochoa
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia.,Semillero de Investigación, Biofísica y Fisiología de Canales Iónicos, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Liliana Otero
- Center of Dental Research Dentistry Faculty, Pontificia Universidad Javeriana, Bogotá, Colombia
| | | | - Fernando Hinostroza
- Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del Maule, Talca, Chile.,Centro de Investigación de Estudios Avanzados del Maule, CIEAM, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile.,Facultad de Ciencias de la Salud, Centro de Investigación en Neuropsicología y Neurociencias Cognitivas, Universidad Católica del Maule, Talca, Chile
| | - Ingrid Carvacho
- Department of Biology and Chemistry, Faculty of Basic Sciences, Universidad Católica del Maule, Talca, Chile
| | - Yolima P Torres
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia.,Semillero de Investigación, Biofísica y Fisiología de Canales Iónicos, Pontificia Universidad Javeriana, Bogotá, Colombia
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Imaizumi Y. Reciprocal Relationship between Ca 2+ Signaling and Ca 2+-Gated Ion Channels as a Potential Target for Drug Discovery. Biol Pharm Bull 2022; 45:1-18. [PMID: 34980771 DOI: 10.1248/bpb.b21-00896] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cellular Ca2+ signaling functions as one of the most common second messengers of various signal transduction pathways in cells and mediates a number of physiological roles in a cell-type dependent manner. Ca2+ signaling also regulates more general and fundamental cellular activities, including cell proliferation and apoptosis. Among ion channels, Ca2+-permeable channels in the plasma membrane as well as endo- and sarcoplasmic reticulum membranes play important roles in Ca2+ signaling by directly contributing to the influx of Ca2+ from extracellular spaces or its release from storage sites, respectively. Furthermore, Ca2+-gated ion channels in the plasma membrane often crosstalk reciprocally with Ca2+ signals and are central to the regulation of cellular functions. This review focuses on the physiological and pharmacological impact of i) Ca2+-gated ion channels as an apparatus for the conversion of cellular Ca2+ signals to intercellularly propagative electrical signals and ii) the opposite feedback regulation of Ca2+ signaling by Ca2+-gated ion channel activities in excitable and non-excitable cells.
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Affiliation(s)
- Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University
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43
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Estrogen-Induced Uterine Vasodilation in Pregnancy and Preeclampsia. MATERNAL-FETAL MEDICINE 2022; 4:52-60. [PMID: 35072088 PMCID: PMC8772435 DOI: 10.1097/fm9.0000000000000132] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 11/09/2021] [Indexed: 12/02/2022] Open
Abstract
Normal pregnancy is associated with dramatically increased estrogen biosynthesis whose role is believed to raise uterine blood flow to facilitate the bi-directional maternal-fetal exchanges of gases (O2 and CO2), to deliver nutrients, and exhaust wastes to support fetal development and survival. Constrained uterine blood flow in pregnancy is a leading cause of preeclampsia with fetal growth restriction, rendering investigations of uterine hemodynamics to hold a high promise to inform pathways as targets for therapeutic interventions for preeclampsia. The mechanisms of estrogen-induced uterine vasodilation in pregnancy have long been attributed to enhanced endothelium production of nitric oxide, but clinical trials targeting this pathway that dominates uterine hemodynamics have achieved no to little success. Emerging evidence has recently shown a novel proangiogenic vasodilatory role of hydrogen sulfide in regulating uterine hemodynamics in pregnancy and preeclampsia, provoking a new field of perinatal research in searching for alternative pathways for pregnancy disorders especially preeclampsia and intrauterine growth restriction. This minireview is intended to summarize the nitric oxide pathway and to discuss the emerging hydrogen sulfide pathway in modulating estrogen-induced uterine vasodilation in pregnancy and preeclampsia.
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Moldenhauer HJ, Dinsdale RL, Alvarez S, Fernández-Jaén A, Meredith AL. Effect of an autism-associated KCNMB2 variant, G124R, on BK channel properties. Curr Res Physiol 2022; 5:404-413. [PMID: 36203817 PMCID: PMC9531041 DOI: 10.1016/j.crphys.2022.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 08/26/2022] [Accepted: 09/20/2022] [Indexed: 11/30/2022] Open
Abstract
BK K+ channels are critical regulators of neuron and muscle excitability, comprised of a tetramer of pore-forming αsubunits from the KCNMA1 gene and cell- and tissue-selective β subunits (KCNMB1-4). Mutations in KCNMA1 are associated with neurological disorders, including autism. However, little is known about the role of neuronal BK channel β subunits in human neuropathology. The β2 subunit is expressed in central neurons and imparts inactivation to BK channels, as well as altering activation and deactivation gating. In this study, we report the functional effect of G124R, a novel KCNMB2 mutation obtained from whole-exome sequencing of a patient diagnosed with autism spectrum disorder. Residue G124, located in the extracellular loop between TM1 and TM2, is conserved across species, and the G124R missense mutation is predicted deleterious with computational tools. To investigate the pathogenicity potential, BK channels were co-expressed with β2WT and β2G124R subunits in HEK293T cells. BK/β2 currents were assessed from inside-out patches under physiological K+ conditions (140/6 mM K+ and 10 μM Ca2+) during activation and inactivation (voltage-dependence and kinetics). Using β2 subunits lacking inactivation (β2IR) revealed that currents from BK/β2IRG124R channels activated 2-fold faster and deactivated 2-fold slower compared with currents from BK/β2IRWT channels, with no change in the voltage-dependence of activation (V1/2). Despite the changes in the BK channel opening and closing, BK/β2G124R inactivation rates (τinact and τrecovery), and the V1/2 of inactivation, were unaltered compared with BK/β2WT channels under standard steady-state voltage protocols. Action potential-evoked current was also unchanged. Thus, the mutant phenotype suggests the β2G124R TM1-TM2 extracellular loop could regulate BK channel activation and deactivation kinetics. However, additional evidence is needed to validate pathogenicity for this patient-associated variant in KCNMB2. KCNMA1 channelopathy is a neurobehavioral disorder associated with seizures, dyskinesia, and intellectual disability. KCNMB2 encodes an accessory β subunit that confers inactivation to the KCNMA1 pore-forming α subunit BK channel. The KCNMB2-G124R variant, identified in an autistic individual, affects BK/β2 channel activation but not inactivation.
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Affiliation(s)
- Hans J. Moldenhauer
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ria L. Dinsdale
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Alberto Fernández-Jaén
- Dept. of Pediatric Neurology, Hospital Universitario Quirónsalud, School of Medicine, Universidad Europea de, Madrid, Spain
| | - Andrea L. Meredith
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Corresponding author. Dept. of Physiology University of Maryland School of Medicine, 655 W. Baltimore St. Baltimore, MD, 21201, USA.
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Yang C, Yang Z, Tong K, Wang J, Yang W, Yu R, Jiang F, Ji Y. Homology modeling and molecular docking simulation of martentoxin as a specific inhibitor of the BK channel. ANNALS OF TRANSLATIONAL MEDICINE 2022; 10:71. [PMID: 35282126 PMCID: PMC8848368 DOI: 10.21037/atm-21-6967] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 01/13/2022] [Indexed: 11/18/2022]
Abstract
Background Large conductance calcium-activated potassium channel (BK channel) is gated by both voltage and calcium ions and is widely distributed in excitable and nonexcitable cells. BK channel plays an important role in epilepsy and other diseases, but BK channel subtype-specific drugs are still extremely rare. Martentoxin was previously isolated from the venom of members of Scorpionidae and shown to be composed of 37 amino acids. Research has shown that the pharmacological selectivity of martentoxin to the BK channel is higher than that to other potassium channels. Therefore, it is of great significance to study the mechanism of interaction between martentoxin and BK channels. Methods The three-dimensional structure of BK channel pore region was constructed by homologous modeling method, and the key amino acid sites of BK channel interaction with martentoxin were analyzed by protein-protein docking, molecular dynamic simulation and virtual alanine mutation. Results Based on homologous modeling of BK channel pore structure and protein-protein docking analysis, Phe1, Lys28 and Arg35 of martentoxin were found to be key amino acids in toxin BK channel interaction. Conclusions This study reveals the structural basis of martentoxin interaction with BK channel. These results will contribute to the design of BK channel specific blockers based on the structure of martentoxin.
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Affiliation(s)
- Chao Yang
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Zihao Yang
- College of Life Sciences and Food Engineering, Huaiyin Institute of Technology, Huai'an, China
| | - Kuiyuan Tong
- College of Life Sciences and Food Engineering, Huaiyin Institute of Technology, Huai'an, China
| | - Jiawei Wang
- School of Life and Medicine Sciences, Shanghai University, Shanghai, China
| | - Wanli Yang
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Ruihua Yu
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Feng Jiang
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Yonghua Ji
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China.,School of Life and Medicine Sciences, Shanghai University, Shanghai, China
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Ohya S, Kajikuri J, Endo K, Kito H, Matsui M. K Ca1.1 K + Channel Inhibition Overcomes Resistance to Antiandrogens and Doxorubicin in a Human Prostate Cancer LNCaP Spheroid Model. Int J Mol Sci 2021; 22:13553. [PMID: 34948357 PMCID: PMC8706449 DOI: 10.3390/ijms222413553] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 12/13/2021] [Indexed: 12/21/2022] Open
Abstract
Several types of K+ channels play crucial roles in tumorigenicity, stemness, invasiveness, and drug resistance in cancer. Spheroid formation of human prostate cancer (PC) LNCaP cells with ultra-low attachment surface cultureware induced the up-regulation of cancer stem cell markers, such as NANOG, and decreased the protein degradation of the Ca2+-activated K+ channel KCa1.1 by down-regulating the E3 ubiquitin ligase, FBXW7, compared with LNCaP monolayers. Accordingly, KCa1.1 activator-induced hyperpolarizing responses were larger in isolated cells from LNCaP spheroids. The pharmacological inhibition of KCa1.1 overcame the resistance of LNCaP spheroids to antiandrogens and doxorubicin (DOX). The protein expression of androgen receptors (AR) was significantly decreased by LNCaP spheroid formation and reversed by KCa1.1 inhibition. The pharmacological and genetic inhibition of MDM2, which may be related to AR protein degradation in PC stem cells, revealed that MDM2 was responsible for the acquisition of antiandrogen resistance in LNCaP spheroids, which was overcome by KCa1.1 inhibition. Furthermore, a member of the multidrug resistance-associated protein subfamily of ABC transporters, MRP5 was responsible for the acquisition of DOX resistance in LNCaP spheroids, which was also overcome by KCa1.1 inhibition. Collectively, the present results suggest the potential of KCa1.1 in LNCaP spheroids, which mimic PC stem cells, as a therapeutic target for overcoming antiandrogen- and DOX-resistance in PC cells.
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Affiliation(s)
- Susumu Ohya
- Department of Pharmacology, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-8601, Japan; (J.K.); (K.E.); (H.K.); (M.M.)
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González-Cota AL, Santana-Calvo C, Servín-Vences R, Orta G, Balderas E. Regulatory mechanisms of mitochondrial BK Ca channels. Channels (Austin) 2021; 15:424-437. [PMID: 33955332 PMCID: PMC8117780 DOI: 10.1080/19336950.2021.1919463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/05/2021] [Accepted: 04/05/2021] [Indexed: 02/06/2023] Open
Abstract
The mitochondrial BKCa channel (mitoBKCa) is a splice variant of plasma membrane BKCa (Maxi-K, BKCa, Slo1, KCa1.1). While a high-resolution structure of mitoBKCa is not available yet, functional and structural studies of the plasma membrane BKCa have provided important clues on the gating of the channel by voltage and Ca2+, as well as the interaction with auxiliary subunits. To date, we know that the control of expression of mitoBKCa, targeting and voltage-sensitivity strongly depends on its association with its regulatory β1-subunit, which overall participate in the control of mitochondrial Ca2+-overload in cardiac myocytes. Moreover, novel regulatory mechanisms of mitoBKCa such as β-subunits and amyloid-β have recently been proposed. However, major basic questions including how the regulatory BKCa-β1-subunit reaches mitochondria and the mechanism through which amyloid-β impairs mitoBKCa channel function remain to be addressed.
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Affiliation(s)
- Ana L. González-Cota
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, UNAM. Av. Universidad 2001, Cuernavaca, Morelos, México
| | - Carmen Santana-Calvo
- Instituto Gulbenkian de Ciência. Rua da Quinta Grande 6, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica, Universida de Nova de Lisboa. Av. da República, Oeiras, Portugal
| | - Rocío Servín-Vences
- Department of Neuroscience, The Scripps Research Institute. 10550 North Torrey Pines Road, La Jolla, CA, USA
| | - Gerardo Orta
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, UNAM. Av. Universidad 2001, Cuernavaca, Morelos, México
| | - Enrique Balderas
- Nora Eccles Harrison Cardiovascular Research & Training Institute, University of Utah, Salt Lake City, UT, USA
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Miller JP, Moldenhauer HJ, Keros S, Meredith AL. An emerging spectrum of variants and clinical features in KCNMA1-linked channelopathy. Channels (Austin) 2021; 15:447-464. [PMID: 34224328 PMCID: PMC8259716 DOI: 10.1080/19336950.2021.1938852] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/18/2021] [Accepted: 06/01/2021] [Indexed: 12/13/2022] Open
Abstract
KCNMA1-linked channelopathy is an emerging neurological disorder characterized by heterogeneous and overlapping combinations of movement disorder, seizure, developmental delay, and intellectual disability. KCNMA1 encodes the BK K+ channel, which contributes to both excitatory and inhibitory neuronal and muscle activity. Understanding the basis of the disorder is an important area of active investigation; however, the rare prevalence has hampered the development of large patient cohorts necessary to establish genotype-phenotype correlations. In this review, we summarize 37 KCNMA1 alleles from 69 patients currently defining the channelopathy and assess key diagnostic and clinical hallmarks. At present, 3 variants are classified as gain-of-function with respect to BK channel activity, 14 loss-of-function, 15 variants of uncertain significance, and putative benign/VUS. Symptoms associated with these variants were curated from patient-provided information and prior publications to define the spectrum of clinical phenotypes. In this newly expanded cohort, seizures showed no differential distribution between patients harboring GOF and LOF variants, while movement disorders segregated by mutation type. Paroxysmal non-kinesigenic dyskinesia was predominantly observed among patients with GOF alleles of the BK channel, although not exclusively so, while additional movement disorders were observed in patients with LOF variants. Neurodevelopmental and structural brain abnormalities were prevalent in patients with LOF mutations. In contrast to mutations, disease-associated KCNMA1 single nucleotide polymorphisms were not predominantly related to neurological phenotypes but covered a wider set of peripheral physiological functions. Together, this review provides additional evidence exploring the genetic and biochemical basis for KCNMA1-linked channelopathy and summarizes the clinical repository of patient symptoms across multiple types of KCNMA1 gene variants.
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Affiliation(s)
- Jacob P. Miller
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hans J. Moldenhauer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sotirios Keros
- Department of Pediatrics, Weill Cornell Medical College, New York, NY, USA
| | - Andrea L. Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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Sancho M, Kyle BD. The Large-Conductance, Calcium-Activated Potassium Channel: A Big Key Regulator of Cell Physiology. Front Physiol 2021; 12:750615. [PMID: 34744788 PMCID: PMC8567177 DOI: 10.3389/fphys.2021.750615] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/29/2021] [Indexed: 12/01/2022] Open
Abstract
Large-conductance Ca2+-activated K+ channels facilitate the efflux of K+ ions from a variety of cells and tissues following channel activation. It is now recognized that BK channels undergo a wide range of pre- and post-translational modifications that can dramatically alter their properties and function. This has downstream consequences in affecting cell and tissue excitability, and therefore, function. While finding the “silver bullet” in terms of clinical therapy has remained elusive, ongoing research is providing an impressive range of viable candidate proteins and mechanisms that associate with and modulate BK channel activity, respectively. Here, we provide the hallmarks of BK channel structure and function generally, and discuss important milestones in the efforts to further elucidate the diverse properties of BK channels in its many forms.
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Affiliation(s)
- Maria Sancho
- Department of Pharmacology, University of Vermont, Burlington, VT, United States
| | - Barry D Kyle
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
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Lu T, Lee HC. Coronary Large Conductance Ca 2+-Activated K + Channel Dysfunction in Diabetes Mellitus. Front Physiol 2021; 12:750618. [PMID: 34744789 PMCID: PMC8567020 DOI: 10.3389/fphys.2021.750618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/14/2021] [Indexed: 11/24/2022] Open
Abstract
Diabetes mellitus (DM) is an independent risk of macrovascular and microvascular complications, while cardiovascular diseases remain a leading cause of death in both men and women with diabetes. Large conductance Ca2+-activated K+ (BK) channels are abundantly expressed in arteries and are the key ionic determinant of vascular tone and organ perfusion. It is well established that the downregulation of vascular BK channel function with reduced BK channel protein expression and altered intrinsic BK channel biophysical properties is associated with diabetic vasculopathy. Recent efforts also showed that diabetes-associated changes in signaling pathways and transcriptional factors contribute to the downregulation of BK channel expression. This manuscript will review our current understandings on the molecular, physiological, and biophysical mechanisms that underlie coronary BK channelopathy in diabetes mellitus.
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Affiliation(s)
- Tong Lu
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Hon-Chi Lee
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
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