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Hilgers RHP, Das KC. Redox Regulation of K + Channel: Role of Thioredoxin. Antioxid Redox Signal 2024. [PMID: 39099341 DOI: 10.1089/ars.2023.0416] [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] [Indexed: 08/06/2024]
Abstract
Significance: Potassium channels regulate the influx and efflux of K+ ions in various cell types that generate and propagate action potential associated with excitation, contraction, and relaxation of various cell types. Although redox active cysteines are critically important for channel activity, the redox regulation of K+ channels by thioredoxin (Trx) has not been systematically reviewed. Recent Advances: Redox regulation of K+ channel is now increasingly recognized as drug targets in the pathological condition of several cardiovascular disease processes. The role of Trx in regulation of these channels and its implication in pathological conditions have not been adequately reviewed. This review specifically focuses on the redox-regulatory role of Trx on K+ channel structure and function in physiological and pathophysiological conditions. Critical Issues: Ion channels, including K+ channel, have been implicated in the functioning of cardiomyocyte excitation-contraction coupling, vascular hyperpolarization, cellular proliferation, and neuronal stimulation in physiological and pathophysiological conditions. Although oxidation-reduction of ion channels is critically important in their function, the role of Trx, redox regulatory protein in regulation of these channels, and its implication in pathological conditions need to be studied to gain further insight into channel function. Future Directions: Future studies need to map all redox regulatory pathways in channel structure and function using novel mouse models and redox proteomic and signal transduction studies, which modulate various currents and altered excitability of relevant cells implicated in a pathological condition. We are yet at infancy of studies related to redox control of various K+ channels and structured and focused studies with novel animal models. Antioxid. Redox Signal. 00, 00-00.
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Affiliation(s)
- Rob H P Hilgers
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Kumuda C Das
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
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2
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Huang J, Pan X, Yan N. Structural biology and molecular pharmacology of voltage-gated ion channels. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00763-7. [PMID: 39103479 DOI: 10.1038/s41580-024-00763-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2024] [Indexed: 08/07/2024]
Abstract
Voltage-gated ion channels (VGICs), including those for Na+, Ca2+ and K+, selectively permeate ions across the cell membrane in response to changes in membrane potential, thus participating in physiological processes involving electrical signalling, such as neurotransmission, muscle contraction and hormone secretion. Aberrant function or dysregulation of VGICs is associated with a diversity of neurological, psychiatric, cardiovascular and muscular disorders, and approximately 10% of FDA-approved drugs directly target VGICs. Understanding the structure-function relationship of VGICs is crucial for our comprehension of their working mechanisms and role in diseases. In this Review, we discuss how advances in single-particle cryo-electron microscopy have afforded unprecedented structural insights into VGICs, especially on their interactions with clinical and investigational drugs. We present a comprehensive overview of the recent advances in the structural biology of VGICs, with a focus on how prototypical drugs and toxins modulate VGIC activities. We explore how these structures elucidate the molecular basis for drug actions, reveal novel pharmacological sites, and provide critical clues to future drug discovery.
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Affiliation(s)
- Jian Huang
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Xiaojing Pan
- Institute of Bio-Architecture and Bio-Interactions (IBABI), Shenzhen Medical Academy of Research and Translation (SMART), Shenzhen, Guangdong, China.
| | - Nieng Yan
- Institute of Bio-Architecture and Bio-Interactions (IBABI), Shenzhen Medical Academy of Research and Translation (SMART), Shenzhen, Guangdong, China.
- Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, China.
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3
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Sastre D, Colomer-Molera M, de Benito-Bueno A, Valenzuela C, Fernández-Ballester G, Felipe A. KCNE4-dependent modulation of Kv1.3 pharmacology. Biochem Pharmacol 2024; 226:116368. [PMID: 38880360 DOI: 10.1016/j.bcp.2024.116368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 06/11/2024] [Accepted: 06/13/2024] [Indexed: 06/18/2024]
Abstract
The voltage-dependent potassium channel Kv1.3 is a promising therapeutic target for the treatment of autoimmune and chronic inflammatory disorders. Kv1.3 blockers are effective in treating multiple sclerosis (fampridine) and psoriasis (dalazatide). However, most Kv1.3 pharmacological antagonists are not specific enough, triggering potential side effects and limiting their therapeutic use. Functional Kv are oligomeric complexes in which the presence of ancillary subunits shapes their function and pharmacology. In leukocytes, Kv1.3 associates with KCNE4, which reduces the surface abundance and enhances the inactivation of the channel. This mechanism exerts profound consequences on Kv1.3-related physiological responses. Because KCNE peptides alter the pharmacology of Kv channels, we studied the effects of KCNE4 on Kv1.3 pharmacology to gain insights into pharmacological approaches. To that end, we used margatoxin, which binds the channel pore from the extracellular space, and Psora-4, which blocks the channel from the intracellular side. While KCNE4 apparently did not alter the affinity of either margatoxin or Psora-4, it slowed the inhibition kinetics of the latter in a stoichiometry-dependent manner. The results suggested changes in the Kv1.3 architecture in the presence of KCNE4. The data indicated that while the outer part of the channel mouth remains unaffected, KCNE4 disturbs the intracellular architecture of the complex. Various leukocyte types expressing different Kv1.3/KCNE4 configurations participate in the immune response. Our data provide evidence that the presence of these variable architectures, which affect both the structure of the complex and their pharmacology, should be considered when developing putative therapeutic approaches.
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Affiliation(s)
- Daniel Sastre
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain; Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Magalí Colomer-Molera
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
| | | | - Carmen Valenzuela
- Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, 28029 Madrid, Spain
| | | | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain.
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4
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Kalm T, Schob C, Völler H, Gardeitchik T, Gilissen C, Pfundt R, Klöckner C, Platzer K, Klabunde-Cherwon A, Ries M, Syrbe S, Beccaria F, Madia F, Scala M, Zara F, Hofstede F, Simon MEH, van Jaarsveld RH, Oegema R, van Gassen KLI, Holwerda SJB, Barakat TS, Bouman A, van Slegtenhorst M, Álvarez S, Fernández-Jaén A, Porta J, Accogli A, Mancardi MM, Striano P, Iacomino M, Chae JH, Jang S, Kim SY, Chitayat D, Mercimek-Andrews S, Depienne C, Kampmeier A, Kuechler A, Surowy H, Bertini ES, Radio FC, Mancini C, Pizzi S, Tartaglia M, Gauthier L, Genevieve D, Tharreau M, Azoulay N, Zaks-Hoffer G, Gilad NK, Orenstein N, Bernard G, Thiffault I, Denecke J, Herget T, Kortüm F, Kubisch C, Bähring R, Kindler S. Etiological involvement of KCND1 variants in an X-linked neurodevelopmental disorder with variable expressivity. Am J Hum Genet 2024; 111:1206-1221. [PMID: 38772379 PMCID: PMC11179411 DOI: 10.1016/j.ajhg.2024.04.019] [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: 11/09/2023] [Revised: 04/25/2024] [Accepted: 04/25/2024] [Indexed: 05/23/2024] Open
Abstract
Utilizing trio whole-exome sequencing and a gene matching approach, we identified a cohort of 18 male individuals from 17 families with hemizygous variants in KCND1, including two de novo missense variants, three maternally inherited protein-truncating variants, and 12 maternally inherited missense variants. Affected subjects present with a neurodevelopmental disorder characterized by diverse neurological abnormalities, mostly delays in different developmental domains, but also distinct neuropsychiatric signs and epilepsy. Heterozygous carrier mothers are clinically unaffected. KCND1 encodes the α-subunit of Kv4.1 voltage-gated potassium channels. All variant-associated amino acid substitutions affect either the cytoplasmic N- or C-terminus of the channel protein except for two occurring in transmembrane segments 1 and 4. Kv4.1 channels were functionally characterized in the absence and presence of auxiliary β subunits. Variant-specific alterations of biophysical channel properties were diverse and varied in magnitude. Genetic data analysis in combination with our functional assessment shows that Kv4.1 channel dysfunction is involved in the pathogenesis of an X-linked neurodevelopmental disorder frequently associated with a variable neuropsychiatric clinical phenotype.
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Affiliation(s)
- Tassja Kalm
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Claudia Schob
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Hanna Völler
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Thatjana Gardeitchik
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6525 GA, the Netherlands
| | - Christian Gilissen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6525 GA, the Netherlands
| | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6525 GA, the Netherlands
| | - Chiara Klöckner
- Institute of Human Genetics, University of Leipzig Medical Center, 04103 Leipzig, Germany
| | - Konrad Platzer
- Institute of Human Genetics, University of Leipzig Medical Center, 04103 Leipzig, Germany
| | - Annick Klabunde-Cherwon
- Division of Pediatric Epileptology, Centre for Paediatric and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Markus Ries
- Division of Pediatric Epileptology, Centre for Paediatric and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Steffen Syrbe
- Division of Pediatric Epileptology, Centre for Paediatric and Adolescent Medicine, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Francesca Beccaria
- Epilepsy Center, Department of Child Neuropsychiatry, Territorial Social-Health Agency, 46100 Mantova, Italy
| | - Francesca Madia
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Marcello Scala
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16145 Genoa, Italy
| | - Federico Zara
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16145 Genoa, Italy
| | - Floris Hofstede
- Department of General Pediatrics, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, the Netherlands
| | - Marleen E H Simon
- Department of Clinical Genetics, University Medical Center Utrecht, Utrecht 3584 EA, the Netherlands
| | - Richard H van Jaarsveld
- Department of Clinical Genetics, University Medical Center Utrecht, Utrecht 3584 EA, the Netherlands
| | - Renske Oegema
- Department of Clinical Genetics, University Medical Center Utrecht, Utrecht 3584 EA, the Netherlands
| | - Koen L I van Gassen
- Department of Clinical Genetics, University Medical Center Utrecht, Utrecht 3584 EA, the Netherlands
| | - Sjoerd J B Holwerda
- Department of Clinical Genetics, University Medical Center Utrecht, Utrecht 3584 EA, the Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam 3000 CA, the Netherlands; ENCORE Expertise Center for Neurodevelopmental Disorders, Erasmus MC University Medical Center, Rotterdam 3000 CA, the Netherlands; Discovery Unit, Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam 3000 CA, the Netherlands
| | - Arjan Bouman
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam 3000 CA, the Netherlands
| | - Marjon van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam 3000 CA, the Netherlands
| | - Sara Álvarez
- Genomics and Medicine, NIMGenetics, 28108 Madrid, Spain
| | - Alberto Fernández-Jaén
- Pediatric Neurology Department, Quironsalud University Hospital Madrid, School of Medicine, European University of Madrid, 28224 Madrid, Spain
| | - Javier Porta
- Genomics, Genologica Medica, 29016 Málaga, Spain
| | - Andrea Accogli
- Division of Medical Genetics, Department of Specialized Medicine, Montreal Children's Hospital, McGill University Health Centre, QC H4A 3J1 Montreal, Canada; Department of Human Genetics, McGill University, QC H4A 3J1 Montreal, Canada
| | | | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16145 Genoa, Italy; Pediatric Neurology and Neuromuscular Diseases Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Michele Iacomino
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Jong-Hee Chae
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 110-744, Republic of Korea; Department of Genomic Medicine, Rare Disease Center, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - SeSong Jang
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 110-744, Republic of Korea
| | - Soo Y Kim
- Department of Genomic Medicine, Rare Disease Center, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - David Chitayat
- The Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto ON M5G 1E2 Toronto, Canada; Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for SickKids, University of Toronto, M5G 1X8 Toronto, Canada
| | - Saadet Mercimek-Andrews
- Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for SickKids, University of Toronto, M5G 1X8 Toronto, Canada; Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, AB T6G 2H7 Edmonton, Canada
| | - Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany
| | - Antje Kampmeier
- Institute of Human Genetics, University Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany
| | - Alma Kuechler
- Institute of Human Genetics, University Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany
| | - Harald Surowy
- Institute of Human Genetics, University Hospital Essen, University Duisburg-Essen, 45122 Essen, Germany
| | | | | | - Cecilia Mancini
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146 Rome, Italy
| | - Simone Pizzi
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146 Rome, Italy
| | - Marco Tartaglia
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146 Rome, Italy
| | - Lucas Gauthier
- Department of Molecular Genetics and Cytogenomics, Rare and Autoinflammatory Diseases Unit, University Hospital of Montpellier, 34295 Montpellier, France
| | - David Genevieve
- Montpellier University, Inserm U1183, Montpellier, France; Department of Clinical Genetics, University Hospital of Montpellier, 34295 Montpellier, France
| | - Mylène Tharreau
- Department of Molecular Genetics and Cytogenomics, Rare and Autoinflammatory Diseases Unit, University Hospital of Montpellier, 34295 Montpellier, France
| | - Noy Azoulay
- The Genetic Institute of Maccabi Health Services, Rehovot 7610000, Israel; Raphael Recanati Genetics Institute, Beilinson Hospital, Rabin Medical Center, Petach Tikva 49100, Israel
| | - Gal Zaks-Hoffer
- Raphael Recanati Genetics Institute, Beilinson Hospital, Rabin Medical Center, Petach Tikva 49100, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Nesia K Gilad
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel; Pediatric Genetics Unit, Schneider Children's Medical Center of Israel, Petah Tikvah 4920235, Israel
| | - Naama Orenstein
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel; Pediatric Genetics Unit, Schneider Children's Medical Center of Israel, Petah Tikvah 4920235, Israel
| | - Geneviève Bernard
- Division of Medical Genetics, Department of Specialized Medicine, Montreal Children's Hospital, McGill University Health Centre, QC H4A 3J1 Montreal, Canada; Departments of Neurology and Neurosurgery, Pediatrics and Human Genetics, McGill University, Montreal, Canada; Child Health and Human Development Program, Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Isabelle Thiffault
- Genomic Medicine Center, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, MO, USA; UKMC School of Medicine, University of Missouri Kansas City, Kansas City, MO, USA; Department of Pathology and Laboratory Medicine, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Jonas Denecke
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Theresia Herget
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Fanny Kortüm
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Christian Kubisch
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Robert Bähring
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
| | - Stefan Kindler
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
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Zhu JZ, Li P, Zhang Z, Li XG, Zhong J. The CfKOB1 gene related to cell apoptosis is required for pathogenicity and involved in mycovirus-induced hypovirulence in Colletotrichum fructicola. Int J Biol Macromol 2024; 271:132437. [PMID: 38761910 DOI: 10.1016/j.ijbiomac.2024.132437] [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: 04/02/2024] [Revised: 05/13/2024] [Accepted: 05/15/2024] [Indexed: 05/20/2024]
Abstract
Colletotrichum fructicola is a globally significant phytopathogenic fungus. Mycovirus-induced hypovirulence has great potential for biological control and study of fungal pathogenic mechanisms. We previously reported that the mycovirus Colletotrichum alienum partitivirus 1 (CaPV1) is associated with the hypovirulence of C. fructicola, and the present study aimed to further investigate a host factor and its roles in mycovirus-induced hypovirulence. A gene named CfKOB1, which encodes putative protein homologous to the β-subunit of voltage-gated potassium channels and aldo-keto reductase, is downregulated upon CaPV1 infection and significantly upregulated during the early infection phase of Nicotiana benthamiana by C. fructicola. Deleting the CfKOB1 gene resulted in diminished vegetative growth, decreased production of asexual spores, hindered appressorium formation, reduced virulence, and altered tolerance to abiotic stresses. Transcriptome analysis revealed that CfKOB1 regulates many metabolic pathways as well as the cell cycle and apoptosis. Furthermore, enhanced apoptosis was observed in the ΔCfKOB1 mutants. Viral RNA accumulation was significantly increased in the CfKOB1 deletion mutant. Additionally, our findings demonstrated that CaPV1 infection in the WT strain also induced cell apoptosis. Collectively, these results highlight the diverse biological roles of the CfKOB1 gene in the fungus C. fructicola, while it also participates in mycovirus-induced hypovirulence by regulating apoptosis.
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Affiliation(s)
- Jun Zi Zhu
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha City, Hunan Province 410128, PR China
| | - Ping Li
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha City, Hunan Province 410128, PR China
| | - Zhuo Zhang
- Institute of Plant Protection, Hunan Academy of Agricultural Sciences, Changsha City, Hunan Province 410125, PR China
| | - Xiao Gang Li
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha City, Hunan Province 410128, PR China.
| | - Jie Zhong
- Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha City, Hunan Province 410128, PR China.
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6
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Maraslioglu-Sperber A, Pizzi E, Fisch JO, Kattler K, Ritter T, Friauf E. Molecular and functional profiling of cell diversity and identity in the lateral superior olive, an auditory brainstem center with ascending and descending projections. Front Cell Neurosci 2024; 18:1354520. [PMID: 38846638 PMCID: PMC11153811 DOI: 10.3389/fncel.2024.1354520] [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: 12/12/2023] [Accepted: 03/15/2024] [Indexed: 06/09/2024] Open
Abstract
The lateral superior olive (LSO), a prominent integration center in the auditory brainstem, contains a remarkably heterogeneous population of neurons. Ascending neurons, predominantly principal neurons (pLSOs), process interaural level differences for sound localization. Descending neurons (lateral olivocochlear neurons, LOCs) provide feedback into the cochlea and are thought to protect against acoustic overload. The molecular determinants of the neuronal diversity in the LSO are largely unknown. Here, we used patch-seq analysis in mice at postnatal days P10-12 to classify developing LSO neurons according to their functional and molecular profiles. Across the entire sample (n = 86 neurons), genes involved in ATP synthesis were particularly highly expressed, confirming the energy expenditure of auditory neurons. Two clusters were identified, pLSOs and LOCs. They were distinguished by 353 differentially expressed genes (DEGs), most of which were novel for the LSO. Electrophysiological analysis confirmed the transcriptomic clustering. We focused on genes affecting neuronal input-output properties and validated some of them by immunohistochemistry, electrophysiology, and pharmacology. These genes encode proteins such as osteopontin, Kv11.3, and Kvβ3 (pLSO-specific), calcitonin-gene-related peptide (LOC-specific), or Kv7.2 and Kv7.3 (no DEGs). We identified 12 "Super DEGs" and 12 genes showing "Cluster similarity." Collectively, we provide fundamental and comprehensive insights into the molecular composition of individual ascending and descending neurons in the juvenile auditory brainstem and how this may relate to their specific functions, including developmental aspects.
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Affiliation(s)
- Ayse Maraslioglu-Sperber
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Erika Pizzi
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Jonas O. Fisch
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Kathrin Kattler
- Genetics/Epigenetics Group, Department of Biological Sciences, Saarland University, Saarbrücken, Germany
| | - Tamara Ritter
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern-Landau, Kaiserslautern, Germany
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7
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Bhat S, Rousseau J, Michaud C, Lourenço CM, Stoler JM, Louie RJ, Clarkson LK, Lichty A, Koboldt DC, Reshmi SC, Sisodiya SM, Hoytema van Konijnenburg EMM, Koop K, van Hasselt PM, Démurger F, Dubourg C, Sullivan BR, Hughes SS, Thiffault I, Tremblay ES, Accogli A, Srour M, Blunck R, Campeau PM. Mono-allelic KCNB2 variants lead to a neurodevelopmental syndrome caused by altered channel inactivation. Am J Hum Genet 2024; 111:761-777. [PMID: 38503299 PMCID: PMC11023922 DOI: 10.1016/j.ajhg.2024.02.014] [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: 07/28/2023] [Revised: 02/23/2024] [Accepted: 02/25/2024] [Indexed: 03/21/2024] Open
Abstract
Ion channels mediate voltage fluxes or action potentials that are central to the functioning of excitable cells such as neurons. The KCNB family of voltage-gated potassium channels (Kv) consists of two members (KCNB1 and KCNB2) encoded by KCNB1 and KCNB2, respectively. These channels are major contributors to delayed rectifier potassium currents arising from the neuronal soma which modulate overall excitability of neurons. In this study, we identified several mono-allelic pathogenic missense variants in KCNB2, in individuals with a neurodevelopmental syndrome with epilepsy and autism in some individuals. Recurrent dysmorphisms included a broad forehead, synophrys, and digital anomalies. Additionally, we selected three variants where genetic transmission has not been assessed, from two epilepsy studies, for inclusion in our experiments. We characterized channel properties of these variants by expressing them in oocytes of Xenopus laevis and conducting cut-open oocyte voltage clamp electrophysiology. Our datasets indicate no significant change in absolute conductance and conductance-voltage relationships of most disease variants as compared to wild type (WT), when expressed either alone or co-expressed with WT-KCNB2. However, variants c.1141A>G (p.Thr381Ala) and c.641C>T (p.Thr214Met) show complete abrogation of currents when expressed alone with the former exhibiting a left shift in activation midpoint when expressed alone or with WT-KCNB2. The variants we studied, nevertheless, show collective features of increased inactivation shifted to hyperpolarized potentials. We suggest that the effects of the variants on channel inactivation result in hyper-excitability of neurons, which contributes to disease manifestations.
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Affiliation(s)
- Shreyas Bhat
- Center for Interdisciplinary Research on Brain and Learning (CIRCA), Department of Physics and Department of Pharmacology and Physiology, Université de Montréal, Montréal, QC, Canada
| | - Justine Rousseau
- Centre de Recherche Du Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC H3T 1C5, Canada
| | - Coralie Michaud
- Centre de Recherche Du Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, QC H3T 1C5, Canada
| | | | - Joan M Stoler
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | | | | | - Angie Lichty
- Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Daniel C Koboldt
- Steve and Cindy Rasmussen Institute for Genomic Medicine at Nationwide Children's Hospital, Columbus, OH, USA
| | - Shalini C Reshmi
- Steve and Cindy Rasmussen Institute for Genomic Medicine at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital, Columbus, OH, USA
| | - Sanjay M Sisodiya
- Department of Clinical and Experimental Epilepsy, University College London Queen Square Institute of Neurology, London WC1N 3BG, UK
| | | | - Klaas Koop
- Department of Metabolic Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Peter M van Hasselt
- Department of Genetics, Section Metabolic Diagnostics, University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - Christèle Dubourg
- Department of Molecular Genetics and Genomics, Rennes University Hospital, Rennes, France; Université de Rennes, CNRS, IGDR, UMR 6290 Rennes, France
| | - Bonnie R Sullivan
- Division of Clinical Genetics, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Susan S Hughes
- Division of Clinical Genetics, Department of Pediatrics, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Isabelle Thiffault
- Departments of Pediatrics and of Pathology and Laboratory Medicine, Children's Mercy Kansas City, Kansas City, MO, USA
| | - Elisabeth Simard Tremblay
- Department of Neurology and Neurosurgery, McGill University Health Centre, Montréal, QC, Canada; Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montréal, QC, Canada
| | - Andrea Accogli
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Centre, Montréal, QC, Canada; Department of Human Genetics, Faculty of Medicine, McGill University, Montral, QC H3A 1B1, Canada
| | - Myriam Srour
- Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montréal, QC, Canada; Department of Human Genetics, Faculty of Medicine, McGill University, Montral, QC H3A 1B1, Canada
| | - Rikard Blunck
- Center for Interdisciplinary Research on Brain and Learning (CIRCA), Department of Physics and Department of Pharmacology and Physiology, Université de Montréal, Montréal, QC, Canada.
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8
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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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9
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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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10
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Cheng F, Tang YF, Cao Y, Peng SQ, Zhu XR, Sun Y, Wang SH, Wang B, Lu YM. KCNAB2 overexpression inhibits human non-small-cell lung cancer cell growth in vitro and in vivo. Cell Death Discov 2023; 9:382. [PMID: 37852974 PMCID: PMC10584983 DOI: 10.1038/s41420-023-01679-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/26/2023] [Accepted: 10/11/2023] [Indexed: 10/20/2023] Open
Abstract
Non-small-cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancer cases. NSCLC patients often have poor prognosis demanding urgent identification of novel biomarkers and potential therapeutic targets. KCNAB2 (regulatory beta subunit2 of voltage-gated potassium channel), encoding aldosterone reductase, plays a pivotal role in regulating potassium channel activity. In this research, we tested the expression of KCNAB2 as well as its potential functions in human NSCLC. Bioinformatics analysis shows that expression of KCNAB2 mRNA is significantly downregulated in human NSCLC, correlating with poor overall survival. In addition, decreased KCNAB2 expression was detected in different NSCLC cell lines and local human NSCLC tissues. Exogenous overexpression of KCNAB2 potently suppressed growth, proliferation and motility of established human NSCLC cells and promoted NSCLC cells apoptosis. In contrast, CRISPR/Cas9-induced KCNAB2 knockout further promoted the malignant biological behaviors of NSCLC cells. Protein chip analysis in the KCNAB2-overexpressed NSCLC cells revealed that KCNAB2 plays a possible role in AKT-mTOR cascade activation. Indeed, AKT-mTOR signaling activation was potently inhibited following KCNAB2 overexpression in NSCLC cells. It was however augmented by KCNAB2 knockout. In vivo, the growth of subcutaneous KCNAB2-overexpressed A549 xenografts was significantly inhibited. Collectively, KCNAB2 could be a novel effective gene for prognosis prediction of NSCLC. Targeting KCNAB2 may lead to the development of advanced therapies.
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Affiliation(s)
- Feng Cheng
- Department of Respiratory Medicine, Huzhou Central Hospital, Affiliated Central Hospital, Huzhou University, Huzhou, Zhejiang, China
- Huzhou Key Laboratory of Precision Diagnosis and Treatment in Respiratory Diseases, Huzhou Central Hospital, Huzhou, Zhejiang, China
| | - Yu-Fei Tang
- Department of Soochow Medical college, Soochow University, Suzhou, China
| | - Yang Cao
- Department of Respiratory, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Shi-Qing Peng
- Clinical Research and Lab Center, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Xiao-Ren Zhu
- Clinical Research and Lab Center, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Yue Sun
- Clinical Research and Lab Center, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Shu-Hang Wang
- Clinical Research and Lab Center, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China
| | - Bin Wang
- Department of Respiratory Medicine, Huzhou Central Hospital, Affiliated Central Hospital, Huzhou University, Huzhou, Zhejiang, China.
| | - Yi-Min Lu
- Department of Respiratory, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China.
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11
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Dong W, Fekete A, Chen X, Liu H, Beilhartz GL, Chen X, Bahrampour S, Xiong Y, Yang Q, Zhao H, Kong T, Morioka MS, Jung G, Kim JE, Schramek D, Dirks PB, Song Y, Kim TH, He Y, Wanggou S, Li X, Melnyk RA, Wang LY, Huang X. A designer peptide against the EAG2-Kvβ2 potassium channel targets the interaction of cancer cells and neurons to treat glioblastoma. NATURE CANCER 2023; 4:1418-1436. [PMID: 37697045 DOI: 10.1038/s43018-023-00626-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/02/2023] [Indexed: 09/13/2023]
Abstract
Glioblastoma (GBM) is an incurable brain cancer that lacks effective therapies. Here we show that EAG2 and Kvβ2, which are predominantly expressed by GBM cells at the tumor-brain interface, physically interact to form a potassium channel complex due to a GBM-enriched Kvβ2 isoform. In GBM cells, EAG2 localizes at neuron-contacting regions in a Kvβ2-dependent manner. Genetic knockdown of the EAG2-Kvβ2 complex decreases calcium transients of GBM cells, suppresses tumor growth and invasion and extends the survival of tumor-bearing mice. We engineered a designer peptide to disrupt EAG2-Kvβ2 interaction, thereby mitigating tumor growth in patient-derived xenograft and syngeneic mouse models across GBM subtypes without overt toxicity. Neurons upregulate chemoresistant genes in GBM cells in an EAG2-Kvβ2-dependent manner. The designer peptide targets neuron-associated GBM cells and possesses robust efficacy in treating temozolomide-resistant GBM. Our findings may lead to the next-generation therapeutic agent to benefit patients with GBM.
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Affiliation(s)
- Weifan Dong
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Adam Fekete
- Neurosciences and Mental Health Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Xiaodi Chen
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Hongwei Liu
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Greg L Beilhartz
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Xin Chen
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Shahrzad Bahrampour
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Yi Xiong
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Qi Yang
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Hongyu Zhao
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Tian Kong
- Neurosciences and Mental Health Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Malia S Morioka
- Macaulay Honors College, City College of New York, New York, NY, USA
- Advanced Science Research Center at the Graduate Center, City University of New York, New York, NY, USA
| | - Geena Jung
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ji-Eun Kim
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Daniel Schramek
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Centre for Molecular and Systems Biology, Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Peter B Dirks
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Yuanquan Song
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Tae-Hee Kim
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Ye He
- Macaulay Honors College, City College of New York, New York, NY, USA
- Advanced Science Research Center at the Graduate Center, City University of New York, New York, NY, USA
| | - Siyi Wanggou
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Xuejun Li
- Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China
- Hunan International Scientific and Technological Cooperation Base of Brain Tumor Research, Xiangya Hospital, Central South University, Changsha, China
| | - Roman A Melnyk
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Lu-Yang Wang
- Neurosciences and Mental Health Program, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Xi Huang
- Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
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12
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Orlov NA, Kryukova EV, Efremenko AV, Yakimov SA, Toporova VA, Kirpichnikov MP, Nekrasova OV, Feofanov AV. Interactions of the Kv1.1 Channel with Peptide Pore Blockers: A Fluorescent Analysis on Mammalian Cells. MEMBRANES 2023; 13:645. [PMID: 37505011 PMCID: PMC10383195 DOI: 10.3390/membranes13070645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 06/23/2023] [Accepted: 06/27/2023] [Indexed: 07/29/2023]
Abstract
The voltage-gated potassium channel Kv1.1, which is abundant in the CNS and peripheral nervous system, controls neuronal excitability and neuromuscular transmission and mediates a number of physiological functions in non-excitable cells. The development of some diseases is accompanied by changes in the expression level and/or activity of the channels in particular types of cells. To meet the requirements of studies related to the expression and localization of the Kv1.1 channels, we report on the subnanomolar affinity of hongotoxin 1 N-terminally labeled with Atto 488 fluorophore (A-HgTx) for the Kv1.1 channel and its applicability for fluorescent imaging of the channel in living cells. Taking into consideration the pharmacological potential of the Kv1.1 channel, a fluorescence-based analytical system was developed for the study of peptide ligands that block the ion conductivity of Kv1.1 and are potentially able to correct abnormal activity of the channel. The system is based on analysis of the competitive binding of the studied compounds and A-HgTx to the mKate2-tagged human Kv1.1 (S369T) channel, expressed in the plasma membrane of Neuro2a cells. The system was validated by measuring the affinities of the known Kv1.1-channel peptide blockers, such as agitoxin 2, kaliotoxin 1, hongotoxin 1, and margatoxin. Peptide pore blocker Ce1, from the venom of the scorpion Centruroides elegans, was shown to possess a nanomolar affinity for the Kv1.1 channel. It is reported that interactions of the Kv1.1 channel with the studied peptide blockers are not affected by the transition of the channel from the closed to open state. The conclusion is made that the structural rearrangements accompanying the channel transition into the open state do not change the conformation of the P-loop (including the selectivity filter) involved in the formation of the binding site of the peptide pore blockers.
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Affiliation(s)
- Nikita A Orlov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Elena V Kryukova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Anastasia V Efremenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Sergey A Yakimov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Victoria A Toporova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Mikhail P Kirpichnikov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Oksana V Nekrasova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Alexey V Feofanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
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13
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Koch NA, Sonnenberg L, Hedrich UBS, Lauxmann S, Benda J. Loss or gain of function? Effects of ion channel mutations on neuronal firing depend on the neuron type. Front Neurol 2023; 14:1194811. [PMID: 37292138 PMCID: PMC10244640 DOI: 10.3389/fneur.2023.1194811] [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: 03/27/2023] [Accepted: 05/03/2023] [Indexed: 06/10/2023] Open
Abstract
Introduction Clinically relevant mutations to voltage-gated ion channels, called channelopathies, alter ion channel function, properties of ionic currents, and neuronal firing. The effects of ion channel mutations are routinely assessed and characterized as loss of function (LOF) or gain of function (GOF) at the level of ionic currents. However, emerging personalized medicine approaches based on LOF/GOF characterization have limited therapeutic success. Potential reasons are among others that the translation from this binary characterization to neuronal firing is currently not well-understood-especially when considering different neuronal cell types. In this study, we investigate the impact of neuronal cell type on the firing outcome of ion channel mutations. Methods To this end, we simulated a diverse collection of single-compartment, conductance-based neuron models that differed in their composition of ionic currents. We systematically analyzed the effects of changes in ion current properties on firing in different neuronal types. Additionally, we simulated the effects of known mutations in KCNA1 gene encoding the KV1.1 potassium channel subtype associated with episodic ataxia type 1 (EA1). Results These simulations revealed that the outcome of a given change in ion channel properties on neuronal excitability depends on neuron type, i.e., the properties and expression levels of the unaffected ionic currents. Discussion Consequently, neuron-type specific effects are vital to a full understanding of the effects of channelopathies on neuronal excitability and are an important step toward improving the efficacy and precision of personalized medicine approaches.
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Affiliation(s)
- Nils A. Koch
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
| | - Lukas Sonnenberg
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
| | - Ulrike B. S. Hedrich
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Stephan Lauxmann
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Jan Benda
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
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14
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Paulhus K, Glasscock E. Novel Genetic Variants Expand the Functional, Molecular, and Pathological Diversity of KCNA1 Channelopathy. Int J Mol Sci 2023; 24:8826. [PMID: 37240170 PMCID: PMC10219020 DOI: 10.3390/ijms24108826] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/11/2023] [Accepted: 05/13/2023] [Indexed: 05/28/2023] Open
Abstract
The KCNA1 gene encodes Kv1.1 voltage-gated potassium channel α subunits, which are crucial for maintaining healthy neuronal firing and preventing hyperexcitability. Mutations in the KCNA1 gene can cause several neurological diseases and symptoms, such as episodic ataxia type 1 (EA1) and epilepsy, which may occur alone or in combination, making it challenging to establish simple genotype-phenotype correlations. Previous analyses of human KCNA1 variants have shown that epilepsy-linked mutations tend to cluster in regions critical for the channel's pore, whereas EA1-associated mutations are evenly distributed across the length of the protein. In this review, we examine 17 recently discovered pathogenic or likely pathogenic KCNA1 variants to gain new insights into the molecular genetic basis of KCNA1 channelopathy. We provide the first systematic breakdown of disease rates for KCNA1 variants in different protein domains, uncovering potential location biases that influence genotype-phenotype correlations. Our examination of the new mutations strengthens the proposed link between the pore region and epilepsy and reveals new connections between epilepsy-related variants, genetic modifiers, and respiratory dysfunction. Additionally, the new variants include the first two gain-of-function mutations ever discovered for KCNA1, the first frameshift mutation, and the first mutations located in the cytoplasmic N-terminal domain, broadening the functional and molecular scope of KCNA1 channelopathy. Moreover, the recently identified variants highlight emerging links between KCNA1 and musculoskeletal abnormalities and nystagmus, conditions not typically associated with KCNA1. These findings improve our understanding of KCNA1 channelopathy and promise to enhance personalized diagnosis and treatment for individuals with KCNA1-linked disorders.
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Affiliation(s)
| | - Edward Glasscock
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA;
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15
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Navarro-Pérez M, Estadella I, Benavente-Garcia A, Orellana-Fernández R, Petit A, Ferreres JC, Felipe A. The Phosphorylation of Kv1.3: A Modulatory Mechanism for a Multifunctional Ion Channel. Cancers (Basel) 2023; 15:2716. [PMID: 37345053 DOI: 10.3390/cancers15102716] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/04/2023] [Accepted: 05/09/2023] [Indexed: 06/23/2023] Open
Abstract
The voltage-gated potassium channel Kv1.3 plays a pivotal role in a myriad of biological processes, including cell proliferation, differentiation, and apoptosis. Kv1.3 undergoes fine-tuned regulation, and its altered expression or function correlates with tumorigenesis and cancer progression. Moreover, posttranslational modifications (PTMs), such as phosphorylation, have evolved as rapid switch-like moieties that tightly modulate channel activity. In addition, kinases are promising targets in anticancer therapies. The diverse serine/threonine and tyrosine kinases function on Kv1.3 and the effects of its phosphorylation vary depending on multiple factors. For instance, Kv1.3 regulatory subunits (KCNE4 and Kvβ) can be phosphorylated, increasing the complexity of channel modulation. Scaffold proteins allow the Kv1.3 channelosome and kinase to form protein complexes, thereby favoring the attachment of phosphate groups. This review compiles the network triggers and signaling pathways that culminate in Kv1.3 phosphorylation. Alterations to Kv1.3 expression and its phosphorylation are detailed, emphasizing the importance of this channel as an anticancer target. Overall, further research on Kv1.3 kinase-dependent effects should be addressed to develop effective antineoplastic drugs while minimizing side effects. This promising field encourages basic cancer research while inspiring new therapy development.
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Affiliation(s)
- María Navarro-Pérez
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | - Irene Estadella
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | - Anna Benavente-Garcia
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | | | - Anna Petit
- Departament de Patologia, Hospital Universitari de Bellvitge, IDIBELL, L'Hospitalet del Llobregat, 08908 Barcelona, Spain
| | - Joan Carles Ferreres
- Servei d'Anatomia Patològica, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT-CERCA), 08208 Sabadell, Spain
- Departament de Ciències Morfològiques, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
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16
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Zhou Y, Lin Y, Li W, Liu Q, Gong H, Li Y, Luo D. Expression of AKRs superfamily and prognostic in human gastric cancer. Medicine (Baltimore) 2023; 102:e33041. [PMID: 36827074 PMCID: PMC11309706 DOI: 10.1097/md.0000000000033041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 01/27/2023] [Accepted: 01/31/2023] [Indexed: 02/25/2023] Open
Abstract
The human aldo-keto reductase (AKRs) superfamily is involved in the development of various tumors. However, the different expression patterns of AKRs and their prognostic value in gastric cancer (GC) have not been clarified. In this study, we analyzed the gene expression and gene methylation level of AKRs in GC patients and the survival data and immune infiltration based on AKRs expression, using data from different databases. We found that the expression levels of AKR1B10, AKR1C1, AKR1C2, and AKR7A3 in GC tissues were lower and the expression level of AKR6A5 was higher in GC tissues than in normal tissue. These differentially expressed genes (AKR1B10, AKR1C1, AKR1C2, AKR7A3, and AKR6A5) were significantly correlated with the infiltration level. The expression of SPI1 and AKR6A5 in GC was positively correlated. Survival analysis showed that GC levels of AKR6A5 reduced or increased mRNA levels of AKR7A3, and AKR1B10 was expected to have higher overall survival (OS), first progression (FP) survival, and postprogression survival (PPS) rates and a better prognosis. Moreover, the expression of AKR1B1 was found to be correlated with the staging of GC. The methylation of AKR6A5 (KCNAB2) at cg05307871 and cg01907457 was significantly associated with the classification of GC. Meta-analysis and ROC curve analysis show that the expression level of AKR1B1 and the methylation of cg16156182 (KCNAB1), cg11194299 (KCNAB2), cg16132520 (AKR1B1), and cg13801416 (AKR1B1) had a high hazard ratio and a good prognostic value. These data suggest that the expression and methylation of AKR1B1 and AKR6A5 are significantly related to the prognosis.
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Affiliation(s)
- Yujin Zhou
- NHC Key Laboratory of Metabolic Cardiovascular Diseases Research, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
- Laboratory Medicine Center of Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, China
| | - Yi Lin
- Laboratory Medicine Center of Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, China
| | - Wenjing Li
- Laboratory Medicine Center of Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, China
| | - Quan Liu
- Laboratory Medicine Center of Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, China
| | - Hui Gong
- Laboratory Medicine Center of Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, China
| | - Yifan Li
- NHC Key Laboratory of Metabolic Cardiovascular Diseases Research, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
- Laboratory Medicine Center of Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, China
| | - Dixian Luo
- Laboratory Medicine Center of Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, China
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17
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Hu JH, Liu Y, Hoffman DA. Identification of Kv4.2 protein complex and modifications by tandem affinity purification-mass spectrometry in primary neurons. Front Cell Neurosci 2022; 16:1070305. [PMID: 36568885 PMCID: PMC9788671 DOI: 10.3389/fncel.2022.1070305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/24/2022] [Indexed: 12/13/2022] Open
Abstract
Proteins usually form complexes to fulfill variable physiological functions. In neurons, communication relies on synapses where receptors, channels, and anchoring proteins form complexes to precisely control signal transduction, synaptic integration, and action potential firing. Although there are many published protocols to isolate protein complexes in cell lines, isolation in neurons has not been well established. Here we introduce a method that combines lentiviral protein expression with tandem affinity purification followed by mass-spectrometry (TAP-MS) to identify protein complexes in neurons. This protocol can also be used to identify post-translational modifications (PTMs) of synaptic proteins. We used the A-type voltage-gated K+ channel subunit Kv4.2 as the target protein. Kv4.2 is highly expressed in the hippocampus where it contributes to learning and memory through its regulation of neuronal excitability and synaptic plasticity. We tagged Kv4.2 with the calmodulin-binding-peptide (CBP) and streptavidin-binding-peptide (SBP) at its C-terminus and expressed it in neurons via lentivirus. Kv4.2 was purified by two-step TAP and samples were analyzed by MS. MS identified two prominently known Kv4.2 interacting proteins [dipeptidyl peptidase like (DPPs) and Kv channel-interacting proteins (KChIPs)] in addition to novel synaptic proteins including glutamate receptors, a calcium channel, and anchoring proteins. Co-immunoprecipitation and colocalization experiments validated the association of Kv4.2 with glutamate receptors. In addition to protein complex identification, we used TAP-MS to identify Kv4.2 phosphorylation sites. Several known and unknown phosphorylation sites were identified. These findings provide a novel path to identify protein-protein interactions and PTMs in neurons and shed light on mechanisms of neuronal signaling potentially involved in the pathology of neurological diseases.
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18
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Redel-Traub G, Sampson KJ, Kass RS, Bohnen MS. Potassium Channels as Therapeutic Targets in Pulmonary Arterial Hypertension. Biomolecules 2022; 12:1341. [PMID: 36291551 PMCID: PMC9599705 DOI: 10.3390/biom12101341] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 09/16/2022] [Accepted: 09/18/2022] [Indexed: 12/08/2023] Open
Abstract
Pulmonary arterial hypertension (PAH) is a devastating disease with high morbidity and mortality. Deleterious remodeling in the pulmonary arterial system leads to irreversible arterial constriction and elevated pulmonary arterial pressures, right heart failure, and eventually death. The difficulty in treating PAH stems in part from the complex nature of disease pathogenesis, with several signaling compounds known to be involved (e.g., endothelin-1, prostacyclins) which are indeed targets of PAH therapy. Over the last decade, potassium channelopathies were established as novel causes of PAH. More specifically, loss-of-function mutations in the KCNK3 gene that encodes the two-pore-domain potassium channel KCNK3 (or TASK-1) and loss-of-function mutations in the ABCC8 gene that encodes a key subunit, SUR1, of the ATP-sensitive potassium channel (KATP) were established as the first two potassium channelopathies in human cohorts with pulmonary arterial hypertension. Moreover, voltage-gated potassium channels (Kv) represent a third family of potassium channels with genetic changes observed in association with PAH. While other ion channel genes have since been reported in association with PAH, this review focuses on KCNK3, KATP, and Kv potassium channels as promising therapeutic targets in PAH, with recent experimental pharmacologic discoveries significantly advancing the field.
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Affiliation(s)
- Gabriel Redel-Traub
- Department of Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Kevin J. Sampson
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Robert S. Kass
- Department of Molecular Pharmacology and Therapeutics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Michael S. Bohnen
- Division of Cardiology, Department of Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
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19
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Chiu CY, Tsaur ML. K + channel Kv4.1 is expressed in the nociceptors/secondary nociceptive neurons and participates in pain regulation. Eur J Pain 2022; 26:2238-2256. [PMID: 36097791 DOI: 10.1002/ejp.2038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/01/2022] [Accepted: 09/10/2022] [Indexed: 11/11/2022]
Abstract
BACKGROUND Kv4 channels are key components controlling neuronal excitability at membrane potentials below action potential thresholds. It remains elusive whether Kv4.1 participates in pain regulation. METHODS We raised a Kv4.1 antibody to map Kv4.1+ neurons in the superficial dorsal horn of spinal cord and dorsal root ganglion (DRG) of rats. Behavioral, biochemical, and immunohistochemical methods were used to examine whether the activity of Kv4.1+ neurons or Kv4.1 expression level is altered after peripheral nerve injury. RESULTS In lamina I of spinal cord, Kv4.1 immunoreactivity (IR) was detected in neurokinin-1 receptor positive (NK1R)+ projection neurons (the secondary nociceptive neurons) and NK1R+ excitatory interneurons. Kv4.1, KChIP2 and DPP10 were co-expressed in these neurons. Peripheral nerve injury evoked by lumbar spinal nerve ligation (SNL) immediately induced phosphorylated extracellular regulated protein kinase (pERK, an indicator of enhanced neuronal activity) in lamina I Kv4.1+ neurons and lamina II Kv4.2/Kv4.3+ neurons of the spinal cord. Furthermore, Kv4.1 appeared in 59.9% of DRG neurons with variable sizes. Kv4.1 mRNA and protein levels in DRG neurons were gradually decreased after SNL. Following intrathecal injection of Kv4.1 antisense oligodeoxynucleotide (ASO) into naive rats, Kv4.1 protein level was reduced in the DRG, and mechanical but not thermal hypersensitivity was induced. CONCLUSIONS Kv4.1 appears in the secondary nociceptive neurons, and peripheral nerve injury increases the activity of these neurons. Kv4.1 expression in DRG neurons (including half of the nociceptors) is gradually reduced after peripheral nerve injury, and knockdown of Kv4.1 in DRG neurons induces pain. Thus, Kv4.1 participates in pain regulation. SIGNIFICANCE Based on the expression of Kv4.1 and Kv4.3 in the nociceptors, Kv4.1 in the secondary nociceptive neurons, Kv4.1 in spinal lamina I excitatory interneurons that regulate the activity of the secondary nociceptive neurons, as well as Kv4.2 and Kv4.3 in spinal lamina II excitatory interneurons that also regulate the activity of the secondary nociceptive neurons, developing Kv4 activators or genetic manipulation to increase Kv4 channel activity in these pain-related Kv4+ neurons will be useful in future pain therapeutics.
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Affiliation(s)
- Chi-Yuan Chiu
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Meei-Ling Tsaur
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
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20
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Abbott GW. Kv Channel Ancillary Subunits: Where Do We Go from Here? Physiology (Bethesda) 2022; 37:0. [PMID: 35797055 PMCID: PMC9394777 DOI: 10.1152/physiol.00005.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (Kv) channels each comprise four pore-forming α-subunits that orchestrate essential duties such as voltage sensing and K+ selectivity and conductance. In vivo, however, Kv channels also incorporate regulatory subunits-some Kv channel specific, others more general modifiers of protein folding, trafficking, and function. Understanding all the above is essential for a complete picture of the role of Kv channels in physiology and disease.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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21
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Bauer CK, Holling T, Horn D, Laço MN, Abdalla E, Omar OM, Alawi M, Kutsche K. Clinically Relevant KCNQ1 Variants Causing KCNQ1-KCNE2 Gain-of-Function Affect the Ca2+ Sensitivity of the Channel. Int J Mol Sci 2022; 23:ijms23179690. [PMID: 36077086 PMCID: PMC9456291 DOI: 10.3390/ijms23179690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/18/2022] [Accepted: 08/22/2022] [Indexed: 11/16/2022] Open
Abstract
Dominant KCNQ1 variants are well-known for underlying cardiac arrhythmia syndromes. The two heterozygous KCNQ1 missense variants, R116L and P369L, cause an allelic disorder characterized by pituitary hormone deficiency and maternally inherited gingival fibromatosis. Increased K+ conductance upon co-expression of KCNQ1 mutant channels with the beta subunit KCNE2 is suggested to underlie the phenotype; however, the reason for KCNQ1-KCNE2 (Q1E2) channel gain-of-function is unknown. We aimed to discover the genetic defect in a single individual and three family members with gingival overgrowth and identified the KCNQ1 variants P369L and V185M, respectively. Patch-clamp experiments demonstrated increased constitutive K+ conductance of V185M-Q1E2 channels, confirming the pathogenicity of the novel variant. To gain insight into the pathomechanism, we examined all three disease-causing KCNQ1 mutants. Manipulation of the intracellular Ca2+ concentration prior to and during whole-cell recordings identified an impaired Ca2+ sensitivity of the mutant KCNQ1 channels. With low Ca2+, wild-type KCNQ1 currents were efficiently reduced and exhibited a pre-pulse-dependent cross-over of current traces and a high-voltage-activated component. These features were absent in mutant KCNQ1 channels and in wild-type channels co-expressed with calmodulin and exposed to high intracellular Ca2+. Moreover, co-expression of calmodulin with wild-type Q1E2 channels and loading the cells with high Ca2+ drastically increased Q1E2 current amplitudes, suggesting that KCNE2 normally limits the resting Q1E2 conductance by an increased demand for calcified calmodulin to achieve effective channel opening. Our data link impaired Ca2+ sensitivity of the KCNQ1 mutants R116L, V185M and P369L to Q1E2 gain-of-function that is associated with a particular KCNQ1 channelopathy.
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Affiliation(s)
- Christiane K. Bauer
- Department of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
- Correspondence:
| | - Tess Holling
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Denise Horn
- Department of Medical Genetics and Human Genetics, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin and Berlin Institute of Health, 13353 Berlin, Germany
| | - Mário Nôro Laço
- Medical Genetics Unit, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, 3004-561 Coimbra, Portugal
| | - Ebtesam Abdalla
- Department of Human Genetics, Medical Research Institute, Alexandria University, Alexandria 5422031, Egypt
- Genetics Department, Armed Forces College of Medicine (AFCM), Cairo 4460015, Egypt
| | - Omneya Magdy Omar
- Department of Pediatrics, Faculty of Medicine, Alexandria University, Alexandria 5422031, Egypt
| | - Malik Alawi
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
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22
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Diversification of Potassium Currents in Excitable Cells via Kvβ Proteins. Cells 2022; 11:cells11142230. [PMID: 35883673 PMCID: PMC9317154 DOI: 10.3390/cells11142230] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 07/09/2022] [Accepted: 07/12/2022] [Indexed: 12/10/2022] Open
Abstract
Excitable cells of the nervous and cardiovascular systems depend on an assortment of plasmalemmal potassium channels to control diverse cellular functions. Voltage-gated potassium (Kv) channels are central to the feedback control of membrane excitability in these processes due to their activation by depolarized membrane potentials permitting K+ efflux. Accordingly, Kv currents are differentially controlled not only by numerous cellular signaling paradigms that influence channel abundance and shape voltage sensitivity, but also by heteromeric configurations of channel complexes. In this context, we discuss the current knowledge related to how intracellular Kvβ proteins interacting with pore complexes of Shaker-related Kv1 channels may establish a modifiable link between excitability and metabolic state. Past studies in heterologous systems have indicated roles for Kvβ proteins in regulating channel stability, trafficking, subcellular targeting, and gating. More recent works identifying potential in vivo physiologic roles are considered in light of these earlier studies and key gaps in knowledge to be addressed by future research are described.
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23
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Yee JX, Rastani A, Soden ME. The potassium channel auxiliary subunit Kvβ2 ( Kcnab2) regulates Kv1 channels and dopamine neuron firing. J Neurophysiol 2022; 128:62-72. [PMID: 35788155 PMCID: PMC9273274 DOI: 10.1152/jn.00194.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ion channel complexes typically consist of both pore-forming subunits and auxiliary subunits that do not directly conduct current but can regulate trafficking or alter channel properties. Isolating the role of these auxiliary subunits in neurons has proved difficult due to a lack of specific pharmacological agents and the potential for developmental compensation in constitutive knockout models. Here, we use cell-type-specific viral-mediated CRISPR/Cas9 mutagenesis to target the potassium channel auxiliary subunit Kvβ2 (Kcnab2) in dopamine neurons in the adult mouse brain. We find that mutagenesis of Kcnab2 reduces surface expression of Kv1.2, the primary Kv1 pore-forming subunit expressed in dopamine neurons, and shifts the voltage dependence of inactivation of potassium channel currents toward more hyperpolarized potentials. Loss of Kcnab2 broadens the action potential waveform in spontaneously firing dopamine neurons recorded in slice, reduces the afterhyperpolarization amplitude, and increases spike timing irregularity and excitability, all of which is consistent with a reduction in potassium channel current. Similar effects were observed with mutagenesis of the pore-forming subunit Kv1.2 (Kcna2). These results identify Kv1 currents as important contributors to dopamine neuron firing and demonstrate a role for Kvβ2 subunits in regulating the trafficking and gating properties of these ion channels. Furthermore, they demonstrate the utility of CRISPR-mediated mutagenesis in the study of previously difficult to isolate ion channel subunits.NEW & NOTEWORTHY Here, we utilize CRISPR/Cas9-mediated mutagenesis in dopamine neurons in mice to target the gene encoding Kvβ2, an auxiliary subunit that forms a part of Kv1 channel complexes. We find that the absence of Kvβ2 alters action potential properties by reducing surface expression of pore-forming subunits and shifting the voltage dependence of channel inactivation. This work establishes a new function for Kvβ2 subunits and Kv1 complexes in regulating dopamine neuron activity.
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Affiliation(s)
- Joshua X. Yee
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Ariana Rastani
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Marta E. Soden
- Department of Pharmacology, University of Washington, Seattle, Washington
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24
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Zhu H, Yang X, Li Q, Guo J, Ma T, Liu S, Lin S, Zhou Y, Zhao C, Wang J, Sui J. The Sweetpotato Voltage-Gated K + Channel β Subunit, KIbB1, Positively Regulates Low-K + and High-Salinity Tolerance by Maintaining Ion Homeostasis. Genes (Basel) 2022; 13:genes13061100. [PMID: 35741862 PMCID: PMC9222298 DOI: 10.3390/genes13061100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/17/2022] [Accepted: 06/17/2022] [Indexed: 12/26/2022] Open
Abstract
Voltage-gated K+ channel β subunits act as a structural component of Kin channels in different species. The β subunits are not essential to the channel activity but confer different properties through binding the T1 domain or the C-terminal of α subunits. Here, we studied the physiological function of a novel gene, KIbB1, encoding a voltage-gated K+ channel β subunit in sweetpotato. The transcriptional level of this gene was significantly higher in the low-K+-tolerant line than that in the low-K+-sensitive line under K+ deficiency conditions. In Arabidopsis, KIbB1 positively regulated low-K+ tolerance through regulating K+ uptake and translocation. Under high-salinity stress, the growth conditions of transgenic lines were obviously better than wild typr (WT). Enzymatic and non-enzymatic reactive oxygen species (ROS) scavenging were activated in transgenic plants. Accordingly, the malondialdehyde (MDA) content and the accumulation of ROS such as H2O2 and O2− were lower in transgenic lines under salt stress. It was also found that the overexpression of KIbB1 enhanced K+ uptake, but the translocation from root to shoot was not affected under salt stress. This demonstrates that KIbB1 acted as a positive regulator in high-salinity stress resistance through regulating Na+ and K+ uptake to maintain K+/Na+ homeostasis. These results collectively suggest that the mechanisms of KIbB1 in regulating K+ were somewhat different between low-K+ and high-salinity conditions.
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Affiliation(s)
- Hong Zhu
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Xue Yang
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
- Laboratory of Microbiology, Institute of Biology, Hebei Academy of Sciences, Shijiazhuang 050081, China
| | - Qiyan Li
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Jiayu Guo
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Tao Ma
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Shuyan Liu
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Shunyu Lin
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Yuanyuan Zhou
- Crop Research Institute, Shandong Academy of Agricultural Sciences/Scientific Observing and Experimental Station of Tuber and Root Crops in Huang-Huai-Hai Region, Ministry of Agriculture and Rural Affairs, Jinan 250100, China;
| | - Chunmei Zhao
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Jingshan Wang
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
| | - Jiongming Sui
- College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China; (H.Z.); (X.Y.); (Q.L.); (J.G.); (T.M.); (S.L.); (S.L.); (C.Z.); (J.W.)
- Correspondence:
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25
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Roig SR, Cassinelli S, Zeug A, Ponimaskin E, Felipe A. Oligomerization and Spatial Distribution of Kvβ1.1 and Kvβ2.1 Regulatory Subunits. Front Physiol 2022; 13:930769. [PMID: 35784882 PMCID: PMC9247503 DOI: 10.3389/fphys.2022.930769] [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: 04/28/2022] [Accepted: 06/02/2022] [Indexed: 11/13/2022] Open
Abstract
Members of the regulatory Kvβ family modulate the kinetics and traffic of voltage-dependent K+ (Kv) channels. The crystal structure of Kv channels associated with Kvβ peptides suggests a α4/β4 composition. Although Kvβ2 and Kvβ1 form heteromers, evidence supports that only Kvβ2.1 forms tetramers in the absence of α subunits. Therefore, the stoichiometry of the Kvβ oligomers fine-tunes the activity of hetero-oligomeric Kv channel complexes. We demonstrate that Kvβ subtypes form homo- and heterotetramers with similar affinities. The Kvβ1.1/Kvβ2.1 heteromer showed an altered spatial distribution in lipid rafts, recapitulating the Kvβ1.1 pattern. Because Kvβ2 is an active partner of the Kv1.3-TCR complex at the immunological synapse (IS), an association with Kvβ1 would alter this location, shaping the immune response. Differential regulation of Kvβs influences the traffic and architecture of the Kvβ heterotetramer, modulating Kvβ-dependent physiological responses.
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Affiliation(s)
- Sara R. Roig
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
- Imaging Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Andre Zeug
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Evgeni Ponimaskin
- Department of Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
- *Correspondence: Antonio Felipe,
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26
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Glycogen Synthase Kinase 3: Ion Channels, Plasticity, and Diseases. Int J Mol Sci 2022; 23:ijms23084413. [PMID: 35457230 PMCID: PMC9028019 DOI: 10.3390/ijms23084413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 12/15/2022] Open
Abstract
Glycogen synthase kinase 3β (GSK3) is a multifaceted serine/threonine (S/T) kinase expressed in all eukaryotic cells. GSK3β is highly enriched in neurons in the central nervous system where it acts as a central hub for intracellular signaling downstream of receptors critical for neuronal function. Unlike other kinases, GSK3β is constitutively active, and its modulation mainly involves inhibition via upstream regulatory pathways rather than increased activation. Through an intricate converging signaling system, a fine-tuned balance of active and inactive GSK3β acts as a central point for the phosphorylation of numerous primed and unprimed substrates. Although the full range of molecular targets is still unknown, recent results show that voltage-gated ion channels are among the downstream targets of GSK3β. Here, we discuss the direct and indirect mechanisms by which GSK3β phosphorylates voltage-gated Na+ channels (Nav1.2 and Nav1.6) and voltage-gated K+ channels (Kv4 and Kv7) and their physiological effects on intrinsic excitability, neuronal plasticity, and behavior. We also present evidence for how unbalanced GSK3β activity can lead to maladaptive plasticity that ultimately renders neuronal circuitry more vulnerable, increasing the risk for developing neuropsychiatric disorders. In conclusion, GSK3β-dependent modulation of voltage-gated ion channels may serve as an important pharmacological target for neurotherapeutic development.
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27
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Roig SR, Cassinelli S, Navarro-Pérez M, Pérez-Verdaguer M, Estadella I, Capera J, Felipe A. S-acylation-dependent membrane microdomain localization of the regulatory Kvβ2.1 subunit. Cell Mol Life Sci 2022; 79:230. [PMID: 35396942 PMCID: PMC8994742 DOI: 10.1007/s00018-022-04269-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 03/19/2022] [Accepted: 03/19/2022] [Indexed: 12/13/2022]
Abstract
The voltage-dependent potassium (Kv) channel Kvβ family was the first identified group of modulators of Kv channels. Kvβ regulation of the α-subunits, in addition to their aldoketoreductase activity, has been under extensive study. However, scarce information about their specific α-subunit-independent biology is available. The expression of Kvβs is ubiquitous and, similar to Kv channels, is tightly regulated in leukocytes. Although Kvβ subunits exhibit cytosolic distribution, spatial localization, in close contact with plasma membrane Kv channels, is crucial for a proper immune response. Therefore, Kvβ2.1 is located near cell surface Kv1.3 channels within the immunological synapse during lymphocyte activation. The objective of this study was to analyze the structural elements that participate in the cellular distribution of Kvβs. It was demonstrated that Kvβ peptides, in addition to the cytoplasmic pattern, targeted the cell surface in the absence of Kv channels. Furthermore, Kvβ2.1, but not Kvβ1.1, targeted lipid raft microdomains in an S-acylation-dependent manner, which was concomitant with peptide localization within the immunological synapse. A pair of C-terminal cysteines (C301/C311) was mostly responsible for the specific palmitoylation of Kvβ2.1. Several insults altered Kvβ2.1 membrane localization. Therefore, growth factor-dependent proliferation enhanced surface targeting, whereas PKC activation impaired lipid raft expression. However, PSD95 stabilized Kvβ2.1 in these domains. This data shed light on the molecular mechanism by which Kvβ2.1 clusters into immunological synapses during leukocyte activation.
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Affiliation(s)
- Sara R Roig
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.,Imaging Core Facility, Biozentrum University of Basel, 4056, Basel, Switzerland
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - María Navarro-Pérez
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - Mireia Pérez-Verdaguer
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.,Department of Cell Biology, School of Medicine, University of Pittsburgh, 3500 Terrace Street, Pittsburgh, PA, 15261, USA
| | - Irene Estadella
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - Jesusa Capera
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.,Kennedy Institute of Rheumatology, University of Oxford, Oxford, OX3 7FY, UK
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.
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28
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Clerc N, Moqrich A. Diverse roles and modulations of I A in spinal cord pain circuits. Cell Rep 2022; 38:110588. [PMID: 35354022 DOI: 10.1016/j.celrep.2022.110588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/25/2022] [Accepted: 03/08/2022] [Indexed: 11/03/2022] Open
Abstract
This review highlights recent findings of different amplitude ranges, roles, and modulations of A-type K+ currents (IA) in excitatory (GAD67-GFP-) and inhibitory (GAD67-GFP+) interneurons in mouse spinal cord pain pathways. Endogenous neuropeptides, such as TAFA4, oxytocin, and dynorphin in particular, have been reported to modulate IA in these pain pathways, but only TAFA4 has been shown to fully reverse the opposing modulations that occur selectively in LIIo GAD67-GFP- and LIIi GAD67-GFP+ interneurons following both neuropathic and inflammatory pain. If, as hypothesized here, Kv4 subunits underlie IA in both GAD67-GFP- and GAD67-GFP+ interneurons, then IA diversity in spinal cord pain pathways may depend on the interneuron-subtype-selective expression of Kv4 auxiliary subunits with functionally different N-terminal variants. Thus, IA emerges as a good candidate for explaining the mechanisms underlying injury-induced mechanical hypersensitivity.
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Affiliation(s)
- Nadine Clerc
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, 13288 Marseille Cedex 09, France.
| | - Aziz Moqrich
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, 13288 Marseille Cedex 09, France
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29
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D'Avanzo N, Miles AJ, Powl AM, Nichols CG, Wallace BA, O'Reilly AO. The T1-tetramerisation domain of Kv1.2 rescues expression and preserves function of a truncated NaChBac sodium channel. FEBS Lett 2022; 596:772-783. [PMID: 35015304 PMCID: PMC9303580 DOI: 10.1002/1873-3468.14279] [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: 11/11/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 11/18/2022]
Abstract
Cytoplasmic domains frequently promote functional assembly of multimeric ion channels. To investigate structural determinants of this process, we generated the ‘T1‐chimera’ construct of the NaChBac sodium channel by truncating its C‐terminal domain and splicing the T1‐tetramerisation domain of the Kv1.2 channel to the N terminus. Purified T1‐chimera channels were tetrameric, conducted Na+ when reconstituted into proteoliposomes, and were functionally blocked by the drug mibefradil. Both the T1‐chimera and full‐length NaChBac had comparable expression levels in the membrane, whereas a NaChBac mutant lacking a cytoplasmic domain had greatly reduced membrane expression. Our findings support a model whereby bringing the transmembrane regions into close proximity enables their tetramerisation. This phenomenon is found with other channels, and thus, our findings substantiate this as a common assembly mechanism.
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Affiliation(s)
- Nazzareno D'Avanzo
- Department of Pharmacology and Physiology, Université de Montréal, Canada
| | - Andrew J Miles
- Institute of Structural and Molecular Biology, Birkbeck, University of London, UK
| | - Andrew M Powl
- Institute of Structural and Molecular Biology, Birkbeck, University of London, UK
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, USA
| | - B A Wallace
- Institute of Structural and Molecular Biology, Birkbeck, University of London, UK
| | - Andrias O O'Reilly
- School of Biological & Environmental Sciences, Liverpool John Moores University, UK
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30
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Langthaler S, Lozanović Šajić J, Rienmüller T, Weinberg SH, Baumgartner C. Ion Channel Modeling beyond State of the Art: A Comparison with a System Theory-Based Model of the Shaker-Related Voltage-Gated Potassium Channel Kv1.1. Cells 2022; 11:cells11020239. [PMID: 35053355 PMCID: PMC8773569 DOI: 10.3390/cells11020239] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/03/2022] [Accepted: 01/06/2022] [Indexed: 02/04/2023] Open
Abstract
The mathematical modeling of ion channel kinetics is an important tool for studying the electrophysiological mechanisms of the nerves, heart, or cancer, from a single cell to an organ. Common approaches use either a Hodgkin-Huxley (HH) or a hidden Markov model (HMM) description, depending on the level of detail of the functionality and structural changes of the underlying channel gating, and taking into account the computational effort for model simulations. Here, we introduce for the first time a novel system theory-based approach for ion channel modeling based on the concept of transfer function characterization, without a priori knowledge of the biological system, using patch clamp measurements. Using the shaker-related voltage-gated potassium channel Kv1.1 (KCNA1) as an example, we compare the established approaches, HH and HMM, with the system theory-based concept in terms of model accuracy, computational effort, the degree of electrophysiological interpretability, and methodological limitations. This highly data-driven modeling concept offers a new opportunity for the phenomenological kinetic modeling of ion channels, exhibiting exceptional accuracy and computational efficiency compared to the conventional methods. The method has a high potential to further improve the quality and computational performance of complex cell and organ model simulations, and could provide a valuable new tool in the field of next-generation in silico electrophysiology.
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Affiliation(s)
- Sonja Langthaler
- Institute of Health Care Engineering with European Testing Center for Medical Devices, Graz University of Technology, A-8010 Graz, Austria; (S.L.); (J.L.Š.); (T.R.)
| | - Jasmina Lozanović Šajić
- Institute of Health Care Engineering with European Testing Center for Medical Devices, Graz University of Technology, A-8010 Graz, Austria; (S.L.); (J.L.Š.); (T.R.)
- Innovation Center of the Faculty of Mechanical Engineering, University of Belgrade, 11000 Belgrade, Serbia
| | - Theresa Rienmüller
- Institute of Health Care Engineering with European Testing Center for Medical Devices, Graz University of Technology, A-8010 Graz, Austria; (S.L.); (J.L.Š.); (T.R.)
| | - Seth H. Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH 43210, USA;
- Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH 43081, USA
| | - Christian Baumgartner
- Institute of Health Care Engineering with European Testing Center for Medical Devices, Graz University of Technology, A-8010 Graz, Austria; (S.L.); (J.L.Š.); (T.R.)
- Correspondence:
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31
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Wang K, Xu F, Maylie J, Xu J. Anti-Müllerian Hormone Regulation of Synaptic Transmission in the Hippocampus Requires MAPK Signaling and Kv4.2 Potassium Channel Activity. Front Neurosci 2022; 15:772251. [PMID: 34975379 PMCID: PMC8716599 DOI: 10.3389/fnins.2021.772251] [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: 09/07/2021] [Accepted: 12/01/2021] [Indexed: 11/13/2022] Open
Abstract
Anti-Müllerian hormone (AMH) is a paracrine factor generated peripherally by the gonads to regulate gonadal function in adult mammals. We recently reported that AMH and AMH-specific receptor Anti-Müllerian hormone receptor 2 (AMHR2) are expressed in the hippocampus, and exogenous AMH protein rapidly increased synaptic transmission and long-term synaptic plasticity at the CA3-CA1 synapses. Here we examined the cell-specific expression of AMHR2 and the cellular mechanism of rapid boosting effect of AMH on synaptic transmission in mouse hippocampus. Immunofluorescence staining showed that AMHR2 was specifically expressed in the soma and dendrites of hippocampal pyramidal neurons, but not glial cells. Electrophysiological recordings on acute hippocampal slices showed that AMH did not affect AMPAR-mediated or N-Methyl-D-aspartic acid receptor (NMDAR)-mediated excitatory postsynaptic currents at the CA3-CA1 synapses. The small-conductance Ca2+-activated K+ channel (SK2) and A-type K+ channel (Kv4.2) contribute to shaping excitatory postsynaptic potentials (EPSPs) at the CA3-CA1 synapses. Bath application of apamin to block SK2 did not alter AMH effect on increasing EPSPs, whereas blocking Kv4.2 channel with 4-aminopyridine, or chelating internal Ca2+ with BAPTA occluded the action of AMH on boosting EPSPs. Kv4.2 activity is regulated by p38 mitogen-activated kinase (MAPK). Blocking p38 MAPK with SB203580 occluded the effect of AMH on increasing EPSPs. These results show that Kv4.2 channel contributes to the rapid action of AMH on boosting synaptic transmission in a Ca2+- and p38 MAPK-dependent manner. Our findings provide functional evidence that AMH enhances synaptic transmission through Kv4.2 channel in the hippocampus, suggesting a possible role of Kv4.2 channel in AMH-regulated neuronal process underlying learning and memory.
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Affiliation(s)
- Kang Wang
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - Fuhua Xu
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - James Maylie
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States
| | - Jing Xu
- Department of Obstetrics and Gynecology, School of Medicine, Oregon Health & Science University, Portland, OR, United States.,Division of Reproductive and Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, United States
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32
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Alles SRA, Smith PA. Peripheral Voltage-Gated Cation Channels in Neuropathic Pain and Their Potential as Therapeutic Targets. FRONTIERS IN PAIN RESEARCH 2021; 2:750583. [PMID: 35295464 PMCID: PMC8915663 DOI: 10.3389/fpain.2021.750583] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/10/2021] [Indexed: 11/25/2022] Open
Abstract
The persistence of increased excitability and spontaneous activity in injured peripheral neurons is imperative for the development and persistence of many forms of neuropathic pain. This aberrant activity involves increased activity and/or expression of voltage-gated Na+ and Ca2+ channels and hyperpolarization activated cyclic nucleotide gated (HCN) channels as well as decreased function of K+ channels. Because they display limited central side effects, peripherally restricted Na+ and Ca2+ channel blockers and K+ channel activators offer potential therapeutic approaches to pain management. This review outlines the current status and future therapeutic promise of peripherally acting channel modulators. Selective blockers of Nav1.3, Nav1.7, Nav1.8, Cav3.2, and HCN2 and activators of Kv7.2 abrogate signs of neuropathic pain in animal models. Unfortunately, their performance in the clinic has been disappointing; some substances fail to meet therapeutic end points whereas others produce dose-limiting side effects. Despite this, peripheral voltage-gated cation channels retain their promise as therapeutic targets. The way forward may include (i) further structural refinement of K+ channel activators such as retigabine and ASP0819 to improve selectivity and limit toxicity; use or modification of Na+ channel blockers such as vixotrigine, PF-05089771, A803467, PF-01247324, VX-150 or arachnid toxins such as Tap1a; the use of Ca2+ channel blockers such as TTA-P2, TTA-A2, Z 944, ACT709478, and CNCB-2; (ii) improving methods for assessing "pain" as opposed to nociception in rodent models; (iii) recognizing sex differences in pain etiology; (iv) tailoring of therapeutic approaches to meet the symptoms and etiology of pain in individual patients via quantitative sensory testing and other personalized medicine approaches; (v) targeting genetic and biochemical mechanisms controlling channel expression using anti-NGF antibodies such as tanezumab or re-purposed drugs such as vorinostat, a histone methyltransferase inhibitor used in the management of T-cell lymphoma, or cercosporamide a MNK 1/2 inhibitor used in treatment of rheumatoid arthritis; (vi) combination therapy using drugs that are selective for different channel types or regulatory processes; (vii) directing preclinical validation work toward the use of human or human-derived tissue samples; and (viii) application of molecular biological approaches such as clustered regularly interspaced short palindromic repeats (CRISPR) technology.
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Affiliation(s)
- Sascha R A Alles
- Department of Anesthesiology and Critical Care Medicine, University of New Mexico School of Medicine, Albuquerque, NM, United States
| | - Peter A Smith
- Department of Pharmacology, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
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33
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Lamothe SM, Kurata HT. Slc7a5 alters Kvβ-mediated regulation of Kv1.2. J Gen Physiol 2021; 152:151687. [PMID: 32311044 PMCID: PMC7335012 DOI: 10.1085/jgp.201912524] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/22/2020] [Accepted: 03/13/2020] [Indexed: 01/15/2023] Open
Abstract
The voltage-gated potassium channel Kv1.2 plays a pivotal role in neuronal excitability and is regulated by a variety of known and unknown extrinsic factors. The canonical accessory subunit of Kv1.2, Kvβ, promotes N-type inactivation and cell surface expression of the channel. We recently reported that a neutral amino acid transporter, Slc7a5, alters the function and expression of Kv1.2. In the current study, we investigated the effects of Slc7a5 on Kv1.2 in the presence of Kvβ1.2 subunits. We observed that Slc7a5-induced suppression of Kv1.2 current and protein expression was attenuated with cotransfection of Kvβ1.2. However, gating effects mediated by Slc7a5, including disinhibition and a hyperpolarizing shift in channel activation, were observed together with Kvβ-mediated inactivation, indicating convergent regulation of Kv1.2 by both regulatory proteins. Slc7a5 influenced several properties of Kvβ-induced inactivation of Kv1.2, including accelerated inactivation, a hyperpolarizing shift and greater extent of steady-state inactivation, and delayed recovery from inactivation. These modified inactivation properties were also apparent in altered deactivation of the Kv1.2/Kvβ/Slc7a5 channel complex. Taken together, these findings illustrate a functional interaction arising from simultaneous regulation of Kv1.2 by Kvβ and Slc7a5, leading to powerful effects on Kv1.2 expression, gating, and overall channel function.
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Affiliation(s)
- Shawn M Lamothe
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Harley T Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
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34
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Commentary on "Immler et al. (2021) The voltage‑gated potassium channel Kv1.3 regulates neutrophil recruitment during inflammation" Cardiovasc Res 2021 (doi:10.1093/cvr/cvab133) : Roll over-Kv1.3 ! The function of a voltage-gated potassium channel in leucocytes revealed. Pflugers Arch 2021; 473:1587-1588. [PMID: 34459985 PMCID: PMC8433102 DOI: 10.1007/s00424-021-02615-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 08/11/2021] [Accepted: 08/12/2021] [Indexed: 10/25/2022]
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35
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Control of Biophysical and Pharmacological Properties of Potassium Channels by Ancillary Subunits. Handb Exp Pharmacol 2021; 267:445-480. [PMID: 34247280 DOI: 10.1007/164_2021_512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Potassium channels facilitate and regulate physiological processes as diverse as electrical signaling, ion, solute and hormone secretion, fluid homeostasis, hearing, pain sensation, muscular contraction, and the heartbeat. Potassium channels are each formed by either a tetramer or dimer of pore-forming α subunits that co-assemble to create a multimer with a K+-selective pore that in most cases is capable of functioning as a discrete unit to pass K+ ions across the cell membrane. The reality in vivo, however, is that the potassium channel α subunit multimers co-assemble with ancillary subunits to serve specific physiological functions. The ancillary subunits impart specific physiological properties that are often required for a particular activity in vivo; in addition, ancillary subunit interaction often alters the pharmacology of the resultant complex. In this chapter the modes of action of ancillary subunits on K+ channel physiology and pharmacology are described and categorized into various mechanistic classes.
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36
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Roig SR, Solé L, Cassinelli S, Colomer-Molera M, Sastre D, Serrano-Novillo C, Serrano-Albarrás A, Lillo MP, Tamkun MM, Felipe A. Calmodulin-dependent KCNE4 dimerization controls membrane targeting. Sci Rep 2021; 11:14046. [PMID: 34234241 PMCID: PMC8263776 DOI: 10.1038/s41598-021-93562-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 06/23/2021] [Indexed: 12/26/2022] Open
Abstract
The voltage-dependent potassium channel Kv1.3 participates in the immune response. Kv1.3 is essential in different cellular functions, such as proliferation, activation and apoptosis. Because aberrant expression of Kv1.3 is linked to autoimmune diseases, fine-tuning its function is crucial for leukocyte physiology. Regulatory KCNE subunits are expressed in the immune system, and KCNE4 specifically tightly regulates Kv1.3. KCNE4 modulates Kv1.3 currents slowing activation, accelerating inactivation and retaining the channel at the endoplasmic reticulum (ER), thereby altering its membrane localization. In addition, KCNE4 genomic variants are associated with immune pathologies. Therefore, an in-depth knowledge of KCNE4 function is extremely relevant for understanding immune system physiology. We demonstrate that KCNE4 dimerizes, which is unique among KCNE regulatory peptide family members. Furthermore, the juxtamembrane tetraleucine carboxyl-terminal domain of KCNE4 is a structural platform in which Kv1.3, Ca2+/calmodulin (CaM) and dimerizing KCNE4 compete for multiple interaction partners. CaM-dependent KCNE4 dimerization controls KCNE4 membrane targeting and modulates its interaction with Kv1.3. KCNE4, which is highly retained at the ER, contains an important ER retention motif near the tetraleucine motif. Upon escaping the ER in a CaM-dependent pattern, KCNE4 follows a COP-II-dependent forward trafficking mechanism. Therefore, CaM, an essential signaling molecule that controls the dimerization and membrane targeting of KCNE4, modulates the KCNE4-dependent regulation of Kv1.3, which in turn fine-tunes leukocyte physiology.
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Affiliation(s)
- Sara R Roig
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.,Imaging Core Facility, Biozentrum, University of Basel, 4056, Basel, Switzerland
| | - Laura Solé
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.,Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, 80523, USA
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - Magalí Colomer-Molera
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - Daniel Sastre
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - Clara Serrano-Novillo
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - Antonio Serrano-Albarrás
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain
| | - M Pilar Lillo
- Instituto de Química Física Rocasolano, CSIC, 28006, Madrid, Spain
| | - Michael M Tamkun
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, 80523, USA
| | - Antonio Felipe
- Molecular Physiology Laboratory, Dpt. de Bioquímica I Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028, Barcelona, Spain.
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37
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Maverick EE, Leek AN, Tamkun MM. Kv2 channel-AMIGO β-subunit assembly modulates both channel function and cell adhesion molecule surface trafficking. J Cell Sci 2021; 134:jcs256339. [PMID: 34137443 PMCID: PMC8255027 DOI: 10.1242/jcs.256339] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 05/17/2021] [Indexed: 11/20/2022] Open
Abstract
The Kv2 channels encode delayed rectifier currents that regulate membrane potential in many tissues. They also have a non-conducting function to form stable junctions between the endoplasmic reticulum and plasma membranes, creating membrane contact sites that mediate functions distinct from membrane excitability. Therefore, proteins that interact with Kv2.1 and Kv2.2 channels can alter conducting and/or non-conducting channel properties. One member of the AMIGO family of proteins is an auxiliary β-subunit for Kv2 channels and modulates Kv2.1 electrical activity. However, the AMIGO family has two additional members of ∼50% similarity that have not yet been characterized as Kv2 β-subunits. In this work, we show that the surface trafficking and localization of all three AMIGOs are controlled by their assembly with both Kv2 channels. Additionally, assembly of each AMIGO with either Kv2.1 or Kv2.2 hyperpolarizes the channel activation midpoint by -10 mV. However, only AMIGO2 significantly slows inactivation and deactivation, leading to a prolonged open state of Kv2 channels. The co-regulatory effects of Kv2s and AMIGOs likely fine-tune both the electrical and non-electrical properties of the cells in which they are expressed.
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Affiliation(s)
- Emily E. Maverick
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
- Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO 80523, USA
| | - Ashley N. Leek
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
- Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO 80523, USA
| | - Michael M. Tamkun
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
- Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO 80523, USA
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
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38
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Pleiner T, Hazu M, Tomaleri GP, Januszyk K, Oania RS, Sweredoski MJ, Moradian A, Guna A, Voorhees RM. WNK1 is an assembly factor for the human ER membrane protein complex. Mol Cell 2021; 81:2693-2704.e12. [PMID: 33964204 DOI: 10.1016/j.molcel.2021.04.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 03/02/2021] [Accepted: 04/14/2021] [Indexed: 12/13/2022]
Abstract
The assembly of nascent proteins into multi-subunit complexes is a tightly regulated process that must occur at high fidelity to maintain cellular homeostasis. The ER membrane protein complex (EMC) is an essential insertase that requires seven membrane-spanning and two soluble cytosolic subunits to function. Here, we show that the kinase with no lysine 1 (WNK1), known for its role in hypertension and neuropathy, functions as an assembly factor for the human EMC. WNK1 uses a conserved amphipathic helix to stabilize the soluble subunit, EMC2, by binding to the EMC2-8 interface. Shielding this hydrophobic surface prevents promiscuous interactions of unassembled EMC2 and directly competes for binding of E3 ubiquitin ligases, permitting assembly. Depletion of WNK1 thus destabilizes both the EMC and its membrane protein clients. This work describes an unexpected role for WNK1 in protein biogenesis and defines the general requirements of an assembly factor that will apply across the proteome.
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Affiliation(s)
- Tino Pleiner
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Masami Hazu
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Giovani Pinton Tomaleri
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Kurt Januszyk
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Robert S Oania
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Michael J Sweredoski
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Annie Moradian
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Alina Guna
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
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Bali KK, Gandla J, Rangel DR, Castaldi L, Mouritzen P, Agarwal N, Schmelz M, Heppenstall P, Kuner R. A genome-wide screen reveals microRNAs in peripheral sensory neurons driving painful diabetic neuropathy. Pain 2021; 162:1334-1351. [PMID: 33492037 DOI: 10.1097/j.pain.0000000000002159] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 11/23/2020] [Indexed: 12/25/2022]
Abstract
ABSTRACT Diabetes is a leading cause of peripheral neuropathy (diabetic peripheral neuropathy, DPN), and uncontrolled long-lasting hyperglycemia leads to severe complications. A major proportion of diabetics develop excruciating pain with a variable course. Mechanisms leading to painful DPN are not completely understood and treatment options limited. We hypothesized that epigenetic modulation at the level of microRNA (miRNA) expression triggered by metabolic imbalance and nerve damage regulates the course of pain development. We used clinically relevant preclinical models, genome-wide screening, in silico analyses, cellular assays, miRNA fluorescent in situ hybridization, in vivo molecular manipulations, and behavioral analyses in the current study. We identified miRNAs and their targets that critically impact on nociceptive hypersensitivity in painful DPN. Our analyses identify miR-33 and miR-380 expressed in nociceptive neurons as critical denominators of diabetic pain and miR-124-1 as a mediator of physiological nociception. Our comprehensive analyses on the putative mRNA targets for miR-33 or miR-124-1 identified a set of mRNAs that are regulated after miR-33 or miR-124-1 overexpression in dorsal root ganglia in vivo. Our results shed light on the regulation of DPN pathophysiology and implicate specific miRNAs as novel therapeutic targets for treating painful DPN.
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Affiliation(s)
- Kiran Kumar Bali
- Department of Molecular Pharmacology, Pharmacology Institute, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany . Dr. Bali is now with the Department of Experimental Pain Research, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jagadeesh Gandla
- Department of Molecular Pharmacology, Pharmacology Institute, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany . Dr. Bali is now with the Department of Experimental Pain Research, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Daniel Rojas Rangel
- Department of Molecular Pharmacology, Pharmacology Institute, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany . Dr. Bali is now with the Department of Experimental Pain Research, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | | | | | - Nitin Agarwal
- Department of Molecular Pharmacology, Pharmacology Institute, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany . Dr. Bali is now with the Department of Experimental Pain Research, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Martin Schmelz
- Department of Experimental Pain Research, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | | | - Rohini Kuner
- Department of Molecular Pharmacology, Pharmacology Institute, Medical Faculty Heidelberg, Heidelberg University, Heidelberg, Germany . Dr. Bali is now with the Department of Experimental Pain Research, Mannheim Center for Translational Neuroscience (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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40
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Kojima A, Mi X, Fukushima Y, Ding WG, Omatsu-Kanbe M, Matsuura H. Elevation of propofol sensitivity of cardiac I Ks channel by KCNE1 polymorphism D85N. Br J Pharmacol 2021; 178:2690-2708. [PMID: 33763865 DOI: 10.1111/bph.15460] [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: 07/10/2020] [Revised: 03/13/2021] [Accepted: 03/16/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The slowly activating delayed rectifier K+ channel (IKs ), composed of pore-forming KCNQ1 α-subunits and ancillary KCNE1 β-subunits, regulates ventricular repolarization in human heart. Propofol, at clinically used concentrations, modestly inhibits the intact (wild-type) IKs channels and is therefore unlikely to appreciably prolong QT interval in ECG during anaesthesia. However, little information is available concerning the inhibitory effect of propofol on IKs channel associated with its gene variants implicated in QT prolongation. The KCNE1 single nucleotide polymorphism leading to D85N is associated with drug-induced QT prolongation and therefore regarded as a clinically important genetic variant. This study examined whether KCNE1-D85N affects the sensitivity of IKs to inhibition by propofol. EXPERIMENTAL APPROACH Whole-cell patch-clamp and immunostaining experiments were conducted in HEK293 cells and/or mouse cardiomyocyte-derived HL-1 cells, transfected with wild-type KCNQ1, wild-type or variant KCNE1 cDNAs. KEY RESULTS Propofol inhibited KCNQ1/KCNE1-D85N current more potently than KCNQ1/KCNE1 current in HEK293 cells and HL-1 cells. Immunostaining experiments in HEK293 cells revealed that pretreatment with propofol (10 μM) did not appreciably affect cell membrane expression of KCNQ1 and KCNE1 proteins in KCNQ1/KCNE1 and KCNQ1/KCNE1-D85N channels. CONCLUSION AND IMPLICATIONS The KCNE1 polymorphism D85N significantly elevates the sensitivity of IKs to inhibition by propofol. This study detects a functionally important role of KCNE1-D85N polymorphism in conferring genetic susceptibility to propofol-induced QT prolongation and further suggests the possibility that the inhibitory action of anaesthetics on ionic currents becomes exaggerated in patients carrying variants in genes encoding ion channels.
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Affiliation(s)
- Akiko Kojima
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Japan
| | - Xinya Mi
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
| | - Yutaka Fukushima
- Department of Anesthesiology, Shiga University of Medical Science, Otsu, Japan
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
| | | | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Japan
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Murano H, Kaneko T, Zaw SYM, Sone PP, Zaw ZCT, Okada Y, Sunakawa M, Katsube KI, Okiji T. Pulp inflammation induces Kv1.1 K + channel down-regulation in rat thalamus. Oral Dis 2021; 28:1674-1681. [PMID: 33811796 DOI: 10.1111/odi.13866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 03/07/2021] [Accepted: 03/16/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVES Signals from inflamed tooth pulp activate thalamic neurons to evoke central sensitization. We aimed to gain insights into the mechanisms mediating the early phase of pulpal inflammation-induced thalamic neural and glial activation. MATERIALS AND METHODS Pulpal inflammation was induced via the application of mustard oil (MO) to the upper first molar of Wistar rats with local anesthesia (LA) or saline injection. After 0.5, 1, 2, and 24 hr, contralateral thalami were subjected to microarrays, a real-time polymerase chain reaction and immunohistochemistry to identify differentially expressed genes and assess potassium voltage-gated channel subfamily A member 1 (Kv1.1)-expressing axons and glial fibrillary acidic protein (GFAP)-expressing astrocytes. RESULTS The Kv1.1 gene (Kcna1) was down-regulated and the density of Kv1.1-expressing axons decreased in non-anesthetized rats, but not in anesthetized rats 1 hr after the MO treatment. The density of GFAP-expressing astrocytes increased in both groups until 24 hr after the MO treatment, with a greater increase being observed in the saline-injection group than in the LA group. CONCLUSIONS MO induced the transient down-regulation of Kcna1, transiently reduced the density of Kv1.1-expressing axons, and increased astrocytes in thalami within 1 hr of pulpal application. These results suggest central sensitization represented by neuronal hyperexcitability and astrocyte activation.
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Affiliation(s)
- Hiroki Murano
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Tomoatsu Kaneko
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Su Yee Myo Zaw
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Phyo Pyai Sone
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Zar Chi Thein Zaw
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Yamato Okada
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Mitsuhiro Sunakawa
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | | | - Takashi Okiji
- Department of Pulp Biology and Endodontics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
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Deletion of Kvβ2 (AKR6) Attenuates Isoproterenol Induced Cardiac Injury with Links to Solute Carrier Transporter SLC41a3 and Circadian Clock Genes. Metabolites 2021; 11:metabo11040201. [PMID: 33805250 PMCID: PMC8066990 DOI: 10.3390/metabo11040201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/14/2021] [Accepted: 03/22/2021] [Indexed: 11/17/2022] Open
Abstract
Kvβ subunits belong to the aldo-keto reductase superfamily, which plays a significant role in ion channel regulation and modulates the physiological responses. However, the role of Kvβ2 in cardiac pathophysiology was not studied, and therefore, in the present study, we hypothesized that Kvβ2 plays a significant role in cardiovascular pathophysiology by modulating the cardiac excitability and gene responses. We utilized an isoproterenol-infused mouse model to investigate the role of Kvβ2 and the cardiac function, biochemical changes, and molecular responses. The deletion of Kvβ2 attenuated the QTc (corrected QT interval) prolongation at the electrocardiographic (ECG) level after a 14-day isoproterenol infusion, whereas the QTc was significantly prolonged in the littermate wildtype group. Monophasic action potentials verified the ECG changes, suggesting that cardiac changes and responses due to isoproterenol infusion are mediated similarly at both the in vivo and ex vivo levels. Moreover, the echocardiographic function showed no further decrease in the ejection fraction in the isoproterenol-stimulated Kvβ2 knockout (KO) group, whereas the wildtype mice showed significantly decreased function. These experiments revealed that Kvβ2 plays a significant role in cardiovascular pathophysiology. Furthermore, the present study revealed SLC41a3, a major solute carrier transporter affected with a significantly decreased expression in KO vs. wildtype hearts. The electrical function showed that the decreased expression of SLC41a3 in Kvβ2 KO hearts led to decreased Mg2+ responses, whereas, in the wildtype hearts, Mg2+ caused action potential duration (APD) shortening. Based on the in vivo, ex vivo, and molecular evaluations, we identified that the deletion of Kvβ2 altered the cardiac pathophysiology mediated by SLC41a3 and altered the NAD (nicotinamide adenine dinucleotide)-dependent gene responses.
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43
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Ashton C, Rhie SK, Carmichael JD, Zada G. Role of KCNAB2 expression in modulating hormone secretion in somatotroph pituitary adenoma. J Neurosurg 2021; 134:787-793. [PMID: 32109873 DOI: 10.3171/2019.12.jns192435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/17/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Prior profiling of the human pituitary adenoma (PA) DNA methylome showed the potassium channel subunit-encoding gene KCNAB2 to be highly differentially methylated between nonfunctional PAs (NFPAs) and growth hormone (GH)-secreting PAs, with greater KCNAB2 methylation detected in secretory PAs. KCNAB2 encodes an aldo-keto reductase that, among other things, negatively regulates members of the voltage-gated potassium channel (Kv) family. In this study, the authors aimed to determine whether modulation of Kcnab2 expression would alter GH secretion in the GH3 mammosomatotroph rat cell line. In addition, they examined whether dosing GH3 cells with the antiarrhythmic drug quinidine, a known inhibitor of Kv and voltage-gated sodium channels, would affect hormonal secretion. METHODS Previously generated RNA-seq data were reanalyzed to compare KCNAB2 expression levels in human NFPAs and GH-secreting PAs. Kcnab2 was overexpressed in GH3 cells using plasmid transfection and knocked down using shRNA, with confirmation by quantitative polymerase chain reaction (qPCR). GH concentrations in cell culture supernatants collected 24 hours after cell seeding were measured using enzyme-linked immunosorbent assay (ELISA). Separately, quinidine was administered to GH3 cells at graduated doses. GH and prolactin concentrations in supernatants collected 48 hours after quinidine treatment were measured by fluorometric immunoassay. RESULTS Modulation of expression at the transcript level in GH3 cells resulted in proportionate changes in the expression of GH mRNA and secretion of GH peptide, as confirmed by qPCR and ELISA. Specifically, partial knockdown of Kcnab2 was associated with fewer GH RNA transcripts and less GH secretion compared with controls, while augmentation of Kcnab2 expression was associated with more GH transcripts and secretion than the controls. Administration of quinidine (≥ 50 µM) reduced both GH and prolactin secretion in a dose-dependent fashion (p ≤ 0.05). CONCLUSIONS GH secretion in a somatotroph cell line is partially dependent on KCNAB2 gene expression and may be mitigated in vitro by quinidine. These results collectively suggest a potential new target and pharmacological candidate to be considered in the development of clinical therapeutics for acromegaly.
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Affiliation(s)
| | | | - John D Carmichael
- 3Medicine (Division of Endocrinology), Keck School of Medicine, University of Southern California, Los Angeles, California
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Cercós P, Peraza DA, de Benito-Bueno A, Socuéllamos PG, Aziz-Nignan A, Arrechaga-Estévez D, Beato E, Peña-Acevedo E, Albert A, González-Vera JA, Rodríguez Y, Martín-Martínez M, Valenzuela C, Gutiérrez-Rodríguez M. Pharmacological Approaches for the Modulation of the Potassium Channel K V4.x and KChIPs. Int J Mol Sci 2021; 22:ijms22031419. [PMID: 33572566 PMCID: PMC7866805 DOI: 10.3390/ijms22031419] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 02/06/2023] Open
Abstract
Ion channels are macromolecular complexes present in the plasma membrane and intracellular organelles of cells. Dysfunction of ion channels results in a group of disorders named channelopathies, which represent an extraordinary challenge for study and treatment. In this review, we will focus on voltage-gated potassium channels (KV), specifically on the KV4-family. The activation of these channels generates outward currents operating at subthreshold membrane potentials as recorded from myocardial cells (ITO, transient outward current) and from the somata of hippocampal neurons (ISA). In the heart, KV4 dysfunctions are related to Brugada syndrome, atrial fibrillation, hypertrophy, and heart failure. In hippocampus, KV4.x channelopathies are linked to schizophrenia, epilepsy, and Alzheimer's disease. KV4.x channels need to assemble with other accessory subunits (β) to fully reproduce the ITO and ISA currents. β Subunits affect channel gating and/or the traffic to the plasma membrane, and their dysfunctions may influence channel pharmacology. Among KV4 regulatory subunits, this review aims to analyze the KV4/KChIPs interaction and the effect of small molecule KChIP ligands in the A-type currents generated by the modulation of the KV4/KChIP channel complex. Knowledge gained from structural and functional studies using activators or inhibitors of the potassium current mediated by KV4/KChIPs will better help understand the underlying mechanism involving KV4-mediated-channelopathies, establishing the foundations for drug discovery, and hence their treatments.
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Affiliation(s)
- Pilar Cercós
- Instituto de Química Médica (IQM-CSIC), 28006 Madrid, Spain; (P.C.); (M.M.-M.)
| | - Diego A. Peraza
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Angela de Benito-Bueno
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Paula G. Socuéllamos
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Abdoul Aziz-Nignan
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Dariel Arrechaga-Estévez
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Escarle Beato
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Emilio Peña-Acevedo
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Armando Albert
- Instituto de Química Física Rocasolano (IQFR-CSIC), 28006 Madrid, Spain;
| | - Juan A. González-Vera
- Departamento de Físicoquímica, Facultad de Farmacia, Universidad de Granada, 18071 Granada, Spain;
| | - Yoel Rodríguez
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | | | - Carmen Valenzuela
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: ; (C.V.); (M.G.-R.); Tel.: +34-91-585-4493 (C.V.); +34-91-258-7493 (M.-G.R.)
| | - Marta Gutiérrez-Rodríguez
- Instituto de Química Médica (IQM-CSIC), 28006 Madrid, Spain; (P.C.); (M.M.-M.)
- Correspondence: ; (C.V.); (M.G.-R.); Tel.: +34-91-585-4493 (C.V.); +34-91-258-7493 (M.-G.R.)
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Ohanyan V, Raph SM, Dwenger MM, Hu X, Pucci T, Mack G, Moore JB, Chilian WM, Bhatnagar A, Nystoriak MA. Myocardial Blood Flow Control by Oxygen Sensing Vascular Kvβ Proteins. Circ Res 2021; 128:738-751. [PMID: 33499656 DOI: 10.1161/circresaha.120.317715] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Vahagn Ohanyan
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown (V.O., T.P., G.M., W.M.C.)
| | - Sean M Raph
- Division of Environmental Medicine, Department of Medicine, Diabetes and Obesity Center, University of Louisville, KY (S.M.R., M.M.D., X.H., J.B.M., A.B., M.A.N.)
| | - Marc M Dwenger
- Division of Environmental Medicine, Department of Medicine, Diabetes and Obesity Center, University of Louisville, KY (S.M.R., M.M.D., X.H., J.B.M., A.B., M.A.N.)
| | - Xuemei Hu
- Division of Environmental Medicine, Department of Medicine, Diabetes and Obesity Center, University of Louisville, KY (S.M.R., M.M.D., X.H., J.B.M., A.B., M.A.N.)
| | - Thomas Pucci
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown (V.O., T.P., G.M., W.M.C.)
| | - Gregory Mack
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown (V.O., T.P., G.M., W.M.C.)
| | - Joseph B Moore
- Division of Environmental Medicine, Department of Medicine, Diabetes and Obesity Center, University of Louisville, KY (S.M.R., M.M.D., X.H., J.B.M., A.B., M.A.N.)
| | - William M Chilian
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown (V.O., T.P., G.M., W.M.C.)
| | - Aruni Bhatnagar
- Division of Environmental Medicine, Department of Medicine, Diabetes and Obesity Center, University of Louisville, KY (S.M.R., M.M.D., X.H., J.B.M., A.B., M.A.N.)
| | - Matthew A Nystoriak
- Division of Environmental Medicine, Department of Medicine, Diabetes and Obesity Center, University of Louisville, KY (S.M.R., M.M.D., X.H., J.B.M., A.B., M.A.N.)
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Abstract
Kv7.1-Kv7.5 (KCNQ1-5) K+ channels are voltage-gated K+ channels with major roles in neurons, muscle cells and epithelia where they underlie physiologically important K+ currents, such as neuronal M current and cardiac IKs. Specific biophysical properties of Kv7 channels make them particularly well placed to control the activity of excitable cells. Indeed, these channels often work as 'excitability breaks' and are targeted by various hormones and modulators to regulate cellular activity outputs. Genetic deficiencies in all five KCNQ genes result in human excitability disorders, including epilepsy, arrhythmias, deafness and some others. Not surprisingly, this channel family attracts considerable attention as potential drug targets. Here we will review biophysical properties and tissue expression profile of Kv7 channels, discuss recent advances in the understanding of their structure as well as their role in various neurological, cardiovascular and other diseases and pathologies. We will also consider a scope for therapeutic targeting of Kv7 channels for treatment of the above health conditions.
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Zemel BM, Zhi L, Brown EV, Tymanskyj SR, Liang Q, Covarrubias M. PKCε associates with the Kv3.4 channel to promote its expression in a kinase activity-dependent manner. FASEB J 2021; 35:e21241. [PMID: 33368632 DOI: 10.1096/fj.201901877r] [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: 07/24/2019] [Revised: 11/05/2020] [Accepted: 11/19/2020] [Indexed: 01/16/2023]
Abstract
The voltage-gated potassium channel Kv3.4 is a crucial regulator of nociceptive signaling in the dorsal root ganglion (DRG) and the dorsal horn of the spinal cord. Moreover, Kv3.4 dysfunction has been linked to neuropathic pain. Although kinases and phosphatases can directly modulate Kv3.4 gating, the signaling mechanisms regulating the expression and stability of the Kv3.4 protein are generally unknown. We explored a potential role of PKCε and found an unexpected interaction that has a positive effect on Kv3.4 expression. Co-immunoprecipitation studies revealed a physical association between PKCε and Kv3.4 in both heterologous cells and rat DRG neurons. Furthermore, in contrast to the wild-type and constitutively active forms of PKCε, expression of a catalytically inactive form of the enzyme inhibits Kv3.4 expression and membrane localization through a dominant negative effect. Co-expression of Kv3.4 with the wild-type, constitutively active, or catalytically inactive forms of PKCε had no significant effects on Kv3.4 gating. These results suggest that a novel physical interaction of the Kv3.4 channel with functional PKCε primarily determines its stability and localization in DRG neurons. This interaction is akin to those of previously identified accessory ion channel proteins, which could be significant in neural tissues where Kv3.4 regulates electrical signaling.
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Affiliation(s)
- Benjamin M Zemel
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.,Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA.,Vollum Institute, Oregon Health and Science University, Portland, OR, USA
| | - Lianteng Zhi
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.,Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA
| | - Eric V Brown
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.,Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA
| | - Stephen R Tymanskyj
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.,Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA
| | - Qiansheng Liang
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.,Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA
| | - Manuel Covarrubias
- Department of Neuroscience and Vickie and Jack Farber Institute for Neuroscience, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.,Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA
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Barrett PQ, Guagliardo NA, Bayliss DA. Ion Channel Function and Electrical Excitability in the Zona Glomerulosa: A Network Perspective on Aldosterone Regulation. Annu Rev Physiol 2020; 83:451-475. [PMID: 33176563 DOI: 10.1146/annurev-physiol-030220-113038] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aldosterone excess is a pathogenic factor in many hypertensive disorders. The discovery of numerous somatic and germline mutations in ion channels in primary hyperaldosteronism underscores the importance of plasma membrane conductances in determining the activation state of zona glomerulosa (zG) cells. Electrophysiological recordings describe an electrically quiescent behavior for dispersed zG cells. Yet, emerging data indicate that in native rosette structures in situ, zG cells are electrically excitable, generating slow periodic voltage spikes and coordinated bursts of Ca2+ oscillations. We revisit data to understand how a multitude of conductances may underlie voltage/Ca2+ oscillations, recognizing that zG layer self-renewal and cell heterogeneity may complicate this task. We review recent data to understand rosette architecture and apply maxims derived from computational network modeling to understand rosette function. The challenge going forward is to uncover how the rosette orchestrates the behavior of a functional network of conditional oscillators to control zG layer performance and aldosterone secretion.
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Affiliation(s)
- Paula Q Barrett
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA; , ,
| | - Nick A Guagliardo
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA; , ,
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA; , ,
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The potassium channel subunit K vβ1 serves as a major control point for synaptic facilitation. Proc Natl Acad Sci U S A 2020; 117:29937-29947. [PMID: 33168717 PMCID: PMC7703594 DOI: 10.1073/pnas.2000790117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nerve terminals generally engage in two opposite and essential forms of synaptic plasticity (facilitation or depression) that play critical roles in learning and memory. While the molecular components of both types of terminals are similar with regards to vesicle fusion, much less is known about their molecular control of electrical signaling. Measurements of the electrical impulses (action potentials) underlying these two forms of plasticity have been difficult in small nerve terminals due to their size. In this study we deployed optical physiology measurements to overcome this size barrier. Here, we identify a unique mechanism (Kvβ1 subunit) that enables broadening of the presynaptic action potentials that selectively supports synaptic facilitation, but does not alter any other aspects of nerve terminal function. Analysis of the presynaptic action potential’s (APsyn) role in synaptic facilitation in hippocampal pyramidal neurons has been difficult due to size limitations of axons. We overcame these size barriers by combining high-resolution optical recordings of membrane potential, exocytosis, and Ca2+ in cultured hippocampal neurons. These recordings revealed a critical and selective role for Kv1 channel inactivation in synaptic facilitation of excitatory hippocampal neurons. Presynaptic Kv1 channel inactivation was mediated by the Kvβ1 subunit and had a surprisingly rapid onset that was readily apparent even in brief physiological stimulation paradigms including paired-pulse stimulation. Genetic depletion of Kvβ1 blocked all broadening of the APsyn during high-frequency stimulation and eliminated synaptic facilitation without altering the initial probability of vesicle release. Thus, using all quantitative optical measurements of presynaptic physiology, we reveal a critical role for presynaptic Kv channels in synaptic facilitation at presynaptic terminals of the hippocampus upstream of the exocytic machinery.
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Song L, Barrett DG, Cox KL, Efanov AM, Syed SK, Tomandl D, Willard FS. A High-Throughput Assay for the Pancreatic Islet Beta-Cell Potassium Channel: Use in the Pharmacological Characterization of Insulin Secretagogues Identified from Phenotypic Screening. Assay Drug Dev Technol 2020; 19:27-37. [PMID: 33164547 DOI: 10.1089/adt.2020.1011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Phenotypic screening is a neoclassical approach for drug discovery. We conducted phenotypic screening for insulin secretion enhancing agents using INS-1E insulinoma cells as a model system for pancreatic beta-cells. A principal regulator of insulin secretion in beta-cells is the metabolically regulated potassium channel Kir6.2/SUR1 complex. To characterize hit compounds, we developed an assay to quantify endogenous potassium channel activity in INS-1E cells. We quantified ligand-regulated potassium channel activity in INS-1E cells using fluorescence imaging and thallium flux. Potassium channel activity was metabolically regulated and coupled to insulin secretion. The pharmacology of channel opening agents (diazoxide) and closing agents (sulfonylureas) was used to validate the applicability of the assay. A precise high-throughput assay was enabled, and phenotypic screening hits were triaged to enable a higher likelihood of discovering chemical matter with novel and useful mechanisms of action.
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Affiliation(s)
- Luyan Song
- Quantitative Biology, Lilly Research Laboratories, Indianapolis, Indiana, USA
| | - David G Barrett
- Discovery Chemistry, Lilly Research Laboratories, Indianapolis, Indiana, USA
| | - Karen L Cox
- Quantitative Biology, Lilly Research Laboratories, Indianapolis, Indiana, USA
| | - Alexander M Efanov
- Diabetes and Complications Therapeutic Area, Lilly Research Laboratories, Indianapolis, Indiana, USA
| | - Samreen K Syed
- Diabetes and Complications Therapeutic Area, Lilly Research Laboratories, Indianapolis, Indiana, USA
| | - Dirk Tomandl
- Discovery Informatics, Lilly Research Laboratories, Indianapolis, Indiana, USA
| | - Francis S Willard
- Quantitative Biology, Lilly Research Laboratories, Indianapolis, Indiana, USA
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