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Abrahamyan A, Eldstrom J, Sahakyan H, Karagulyan N, Mkrtchyan L, Karapetyan T, Sargsyan E, Kneussel M, Nazaryan K, Schwarz JR, Fedida D, Vardanyan V. Mechanism of external K+ sensitivity of KCNQ1 channels. J Gen Physiol 2023; 155:213880. [PMID: 36809486 PMCID: PMC9960071 DOI: 10.1085/jgp.202213205] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 12/20/2022] [Accepted: 01/31/2023] [Indexed: 02/23/2023] Open
Abstract
KCNQ1 voltage-gated K+ channels are involved in a wide variety of fundamental physiological processes and exhibit the unique feature of being markedly inhibited by external K+. Despite the potential role of this regulatory mechanism in distinct physiological and pathological processes, its exact underpinnings are not well understood. In this study, using extensive mutagenesis, molecular dynamics simulations, and single-channel recordings, we delineate the molecular mechanism of KCNQ1 modulation by external K+. First, we demonstrate the involvement of the selectivity filter in the external K+ sensitivity of the channel. Then, we show that external K+ binds to the vacant outermost ion coordination site of the selectivity filter inducing a diminution in the unitary conductance of the channel. The larger reduction in the unitary conductance compared to whole-cell currents suggests an additional modulatory effect of external K+ on the channel. Further, we show that the external K+ sensitivity of the heteromeric KCNQ1/KCNE complexes depends on the type of associated KCNE subunits.
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Affiliation(s)
- Astghik Abrahamyan
- Molecular Neuroscience Group, Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
| | - Jodene Eldstrom
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia , Vancouver, BC, Canada
| | - Harutyun Sahakyan
- Laboratory of Computational Modeling of Biological Processes, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
| | - Nare Karagulyan
- Molecular Neuroscience Group, Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
| | - Liana Mkrtchyan
- Molecular Neuroscience Group, Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
| | - Tatev Karapetyan
- Molecular Neuroscience Group, Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
| | - Ernest Sargsyan
- Molecular Neuroscience Group, Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
| | - Matthias Kneussel
- Institute for Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg , Hamburg, Germany
| | - Karen Nazaryan
- Laboratory of Computational Modeling of Biological Processes, Institute of Molecular Biology of National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
| | - Jürgen R Schwarz
- Institute for Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg , Hamburg, Germany
| | - David Fedida
- Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia , Vancouver, BC, Canada
| | - Vitya Vardanyan
- Molecular Neuroscience Group, Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia , Yerevan, Armenia
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2
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Dellin M, Rohrbeck I, Asrani P, Schreiber JA, Ritter N, Glorius F, Wünsch B, Budde T, Temme L, Strünker T, Stallmeyer B, Tüttelmann F, Meuth SG, Spehr M, Matschke J, Steinbicker A, Gatsogiannis C, Stoll R, Strutz-Seebohm N, Seebohm G. The second PI(3,5)P 2 binding site in the S0 helix of KCNQ1 stabilizes PIP 2-at the primary PI1 site with potential consequences on intermediate-to-open state transition. Biol Chem 2023; 404:241-254. [PMID: 36809224 DOI: 10.1515/hsz-2022-0247] [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: 08/05/2022] [Accepted: 12/13/2022] [Indexed: 02/23/2023]
Abstract
The Phosphatidylinositol 3-phosphate 5-kinase Type III PIKfyve is the main source for selectively generated phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), a known regulator of membrane protein trafficking. PI(3,5)P2 facilitates the cardiac KCNQ1/KCNE1 channel plasma membrane abundance and therewith increases the macroscopic current amplitude. Functional-physical interaction of PI(3,5)P2 with membrane proteins and its structural impact is not sufficiently understood. This study aimed to identify molecular interaction sites and stimulatory mechanisms of the KCNQ1/KCNE1 channel via the PIKfyve-PI(3,5)P2 axis. Mutational scanning at the intracellular membrane leaflet and nuclear magnetic resonance (NMR) spectroscopy identified two PI(3,5)P2 binding sites, the known PIP2 site PS1 and the newly identified N-terminal α-helix S0 as relevant for functional PIKfyve effects. Cd2+ coordination to engineered cysteines and molecular modeling suggest that repositioning of S0 stabilizes the channel s open state, an effect strictly dependent on parallel binding of PI(3,5)P2 to both sites.
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Affiliation(s)
- Maurice Dellin
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
| | - Ina Rohrbeck
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
| | - Purva Asrani
- Faculty of Chemistry and Biochemistry, Biomolecular NMR Spectroscopy and RUBiospek|NMR, Ruhr University of Bochum, Universitätsstraße 150, D-44780, Bochum, Germany
| | - Julian A Schreiber
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
| | - Nadine Ritter
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Frank Glorius
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, D-48149, Münster, Germany
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Thomas Budde
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
- Institute of Physiology I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149, Münster, Germany
| | - Louisa Temme
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Timo Strünker
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Domagkstraße 11, D-48149, Münster, Germany
- Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Birgit Stallmeyer
- Institute of Reproductive Genetics, University of Münster, Vesaliusweg 12-14, D-48149, Münster, Germany
| | - Frank Tüttelmann
- Institute of Reproductive Genetics, University of Münster, Vesaliusweg 12-14, D-48149, Münster, Germany
| | - Sven G Meuth
- Department of Neurology, Heinrich Heine University Düsseldorf, Moorenstraße 5, D-40225, Düsseldorf, Germany
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Worringerweg 3, D-52074, Aachen, Germany
| | - Johann Matschke
- Institute of Cell Biology (Cancer Research), University Hospital Essen, University of Duisburg-Essen, D-45147, Essen, Germany
| | - Andrea Steinbicker
- Goethe University Frankfurt and University Hospital Frankfurt, Theodor-Stern-Kai 7, D-60590, Frankfurt, Germany
| | - Christos Gatsogiannis
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Busso-Peus Strasse 10, D-48149, Germany
| | - Raphael Stoll
- Faculty of Chemistry and Biochemistry, Biomolecular NMR Spectroscopy and RUBiospek|NMR, Ruhr University of Bochum, Universitätsstraße 150, D-44780, Bochum, Germany
| | - Nathalie Strutz-Seebohm
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
| | - Guiscard Seebohm
- IfGH-Cellular Electrophysiology, Department of Cardiology and Angiology, University Hospital of Münster, Robert-Koch Str. 45, D-48149, Münster, Germany
- GRK 2515, Chemical biology of ion channels (Chembion), Westfälische Wilhelms-Universität Münster, Münster, Germany
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3
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Renkhold L, Kollmann R, Inderwiedenstraße L, Kienitz MC. PKC-isoform specific regulation of receptor desensitization and KCNQ1/KCNE1 K + channel activity by mutant α 1B-adrenergic receptors. Cell Signal 2021; 91:110228. [PMID: 34958868 DOI: 10.1016/j.cellsig.2021.110228] [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: 10/25/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 11/25/2022]
Abstract
Activation of a specific protein kinase C (PKC) isoform during stimulation of Gq protein-coupled receptors (GqPCRs) is determined by homologous receptor desensitization that controls the spatiotemporal formation of downstream Gq signalling molecules. Furthermore, GqPCR-activated PKC isoforms specifically regulate receptor activity via a negative feedback mechanism. In the present study, we investigated the contribution of several phosphorylation sites in the α1B-adrenergic receptor (α1B-AR) for PKC and G protein coupled receptor kinase 2 (GRK2) to homologous receptor desensitization and effector modulation. We analyzed signalling events downstream to human wildtype α1B-ARs and α1B-ARs lacking PKC or GRK2 phosphorylation sites (Δ391-401, α1B-ΔPKC-AR and Δ402-520, α1B-ΔGRK-AR) by means of FRET-based biosensors in HEK293 that served as online-assays of receptor activity. K+ currents through KCNQ1/KCNE1 channels (IKs), which are regulated by both phosphatidylinositol 4,5-bisphosphate (PIP2)-depletion and/or phosphorylation by PKC, were measured as a functional readout of wildtype and mutant α1B-AR receptor activity. As a novel finding, we provide evidence that deletion of PKC and GRK2 phosphorylation sites in α1B-ARs abrogates the contribution of PKCα to homologous receptor desensitization. Instead, the time course of mutant receptor activity was specifically modulated by PKCβ. Mutant α1B-ARs displayed pronounced homologous receptor desensitization that was abolished by PKCβ-specific pharmacological inhibitors. IKs modulation during stimulation of wildtype and mutant α1B-ARs displayed transient inhibition and current facilitation after agonist withdrawal with reduced capability of mutant α1B-ARs to induce IKs inhibition. Pharmacological inhibition of the PKCβ isoform did not augment IKs reduction by mutant α1B-ARs, but shifted IKs modulation towards current facilitation. Coexpression of an inactive (dominant-negative) PKCδ isoform (DN-PKCδ) abolished IKs facilitation in α1B-ΔGRK-AR-expressing cells, but not in α1B-ΔPKC-AR-expressing cells. The data indicate that the differential modulation of IKs activity by α1B-ΔGRK- and α1B-ΔPKC-receptors is attributed to the activation of entirely distinct novel PKC isoforms. To summarize, specific phosphorylation sites within the wildtype and mutant α1B-adrenergic receptors are targeted by different PKC isoforms, resulting in differential regulation of receptor desensitization and effector function.
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Affiliation(s)
- Lina Renkhold
- Klinik für Hautkrankheiten, Universitätsklinikum Münster, Von-Esmarch-Str. 58, D-48149 Münster, Deutschland, Germany
| | - Rike Kollmann
- Department of Cellular Physiology, Institute of Physiology, Ruhr University Bochum, Universitätsstrasse 150, D-44801 Bochum, Germany
| | - Leonie Inderwiedenstraße
- Department of Cellular Physiology, Institute of Physiology, Ruhr University Bochum, Universitätsstrasse 150, D-44801 Bochum, Germany
| | - Marie-Cecile Kienitz
- Department of Cellular Physiology, Institute of Physiology, Ruhr University Bochum, Universitätsstrasse 150, D-44801 Bochum, Germany.
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5
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Kodirov SA. Tale of tail current. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 150:78-97. [PMID: 31238048 DOI: 10.1016/j.pbiomolbio.2019.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/22/2019] [Accepted: 06/20/2019] [Indexed: 02/07/2023]
Abstract
The largest biomass of channel proteins is located in unicellular organisms and bacteria that have no organs. However, orchestrated bidirectional ionic currents across the cell membrane via the channels are important for the functioning of organs of organisms, and equally concern both fauna or flora. Several ion channels are activated in the course of action potentials. One of the hallmarks of voltage-dependent channels is a 'tail current' - deactivation as observed after prior and sufficient activation predominantly at more depolarized potentials e.g. for Kv while upon hyperpolarization for HCN α subunits. Tail current also reflects the timing of channel closure that is initiated upon termination of stimuli. Finally, deactivation of currents during repolarization could be a selective estimate for given channel as in case of HERG, if dedicated long and more depolarized 'tail pulse' is used. Since from a holding potential of e.g. -70 mV are often a family of outward K+ currents comprising IA and IK are simultaneously activated in native cells.
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Affiliation(s)
- Sodikdjon A Kodirov
- Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia; Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA; Almazov Federal Heart, Blood and Endocrinology Centre, Saint Petersburg, 197341, Russia; Institute of Experimental Medicine, I. P. Pavlov Department of Physiology, Russian Academy of Medical Sciences, Saint Petersburg, Russia; Laboratory of Emotions' Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, 02-093, Poland.
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7
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Kienitz MC, Vladimirova D, Müller C, Pott L, Rinne A. Receptor Species-dependent Desensitization Controls KCNQ1/KCNE1 K+ Channels as Downstream Effectors of Gq Protein-coupled Receptors. J Biol Chem 2016; 291:26410-26426. [PMID: 27834678 DOI: 10.1074/jbc.m116.746974] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 11/09/2016] [Indexed: 12/17/2022] Open
Abstract
Activation of Gq protein-coupled receptors (GqPCRs) might induce divergent cellular responses, related to receptor-specific activation of different branches of the Gq signaling pathway. Receptor-specific desensitization provides a mechanism of effector modulation by restricting the spatiotemporal activation of signaling components downstream of Gq We quantified signaling events downstream of GqPCR activation with FRET-based biosensors in CHO and HEK 293 cells. KCNQ1/KCNE1 channels (IKs) were measured as a functional readout of receptor-specific activation. Activation of muscarinic M1 receptors (M1-Rs) caused robust and reversible inhibition of IKs. In contrast, activation of α1B-adrenergic receptors (α1B-ARs) induced transient inhibition of IKs, which turned into delayed facilitation after agonist withdrawal. As a novel finding, we demonstrate that GqPCR-specific kinetics of IKs modulation are determined by receptor-specific desensitization, evident at the level of Gαq activation, phosphatidylinositol 4,5-bisphosphate (PIP2) depletion, and diacylglycerol production. Sustained IKs inhibition during M1-R stimulation is attributed to robust membrane PIP2 depletion, whereas the rapid desensitization of α1B-AR delimits PIP2 reduction and augments current activation by protein kinase C (PKC). Overexpression of Ca2+-independent PKCδ did not affect the time course of α1B-AR-induced diacylglycerol formation, excluding a contribution of PKCδ to α1B-AR desensitization. Pharmacological inhibition of Ca2+-dependent PKC isoforms abolished fast α1B receptor desensitization and augmented IKs reduction, but did not affect IKs facilitation. These data indicate a contribution of Ca2+-dependent PKCs to α1B-AR desensitization, whereas IKs facilitation is induced by Ca2+-independent PKC isoforms. In contrast, neither inhibition of Ca2+-dependent/Ca2+-independent isoforms nor overexpression of PKCδ induced M1 receptor desensitization, excluding a contribution of PKC to M1-R-induced IKs modulation.
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Affiliation(s)
- Marie-Cécile Kienitz
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Dilyana Vladimirova
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Christian Müller
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Lutz Pott
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
| | - Andreas Rinne
- From the Institute of Physiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780 Bochum, Germany
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