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Gao J, McClenaghan C, Matreyek KA, Grange DK, Nichols CG. Rapid Characterization of the Functional and Pharmacological Consequences of Cantú Syndrome K ATP Channel Mutations in Intact Cells. J Pharmacol Exp Ther 2023; 386:298-309. [PMID: 37527933 PMCID: PMC10449099 DOI: 10.1124/jpet.123.001659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/10/2023] [Accepted: 06/01/2023] [Indexed: 08/03/2023] Open
Abstract
Gain-of-function of KATP channels, resulting from mutations in either KCNJ8 (encoding inward rectifier sub-family 6 [Kir6.1]) or ABCC9 (encoding sulphonylurea receptor [SUR2]), cause Cantú syndrome (CS), a channelopathy characterized by excess hair growth, coarse facial appearance, cardiomegaly, and lymphedema. Here, we established a pipeline for rapid analysis of CS mutation consequences in Landing pad HEK 293 cell lines stably expressing wild type (WT) and mutant human Kir6.1 and SUR2B. Thallium-influx and cell membrane potential, reported by fluorescent Tl-sensitive Fluozin-2 and voltage-sensitive bis-(1,3-dibutylbarbituric acid)trimethine oxonol (DiBAC4(3)) dyes, respectively, were used to assess channel activity. In the Tl-influx assay, CS-associated Kir6.1 mutations increased sensitivity to the ATP-sensitive potassium (KATP) channel activator, pinacidil, but there was strikingly little effect of pinacidil for any SUR2B mutations, reflecting unexpected differences in the molecular mechanisms of Kir6.1 versus SUR2B mutations. Compared with the Tl-influx assay, the DiBAC4(3) assay presents more significant signal changes in response to subtle KATP channel activity changes, and all CS mutants (both Kir6.1 and SUR2B), but not WT channels, caused marked hyperpolarization, demonstrating that all mutants were activated under ambient conditions in intact cells. Most SUR2 CS mutations were markedly inhibited by <100 nM glibenclamide, but sensitivity to inhibition by glibenclamide, repaglinide, and PNU37883A was markedly reduced for Kir6.1 CS mutations. Understanding functional consequences of mutations can help with disease diagnosis and treatment. The analysis pipeline we have developed has the potential to rapidly identify mutational consequences, aiding future CS diagnosis, drug discovery, and individualization of treatment. SIGNIFICANCE STATEMENT: We have developed new fluorescence-based assays of channel activities and drug sensitivities of Cantú syndrome (CS) mutations in human Kir6.1/SUR2B-dependent KATP channels, showing that Kir6.1 mutations increase sensitivity to potassium channel openers, while SUR2B mutations markedly reduce K channel opener (KCO) sensitivity. However, both Kir6.1 and SUR2B CS mutations are both more hyperpolarized than WT cells under basal conditions, confirming pathophysiologically relevant gain-of-function, validating DiBAC4(3) fluorescence to characterize hyperpolarization induced by KATP channel activity under basal, non KCO-activated conditions.
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Affiliation(s)
- Jian Gao
- Department of Cell Biology and Physiology (J.G., C.M.C., C.G.N.), Center for the Investigation of Membrane Excitability Diseases (J.G., C.M.C., D.K.G., C.G.N.), and Division of Genetics and Genomic Medicine, Department of Pediatrics (D.K.G.), Washington University in St. Louis, St. Louis, Missouri; and Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio (K.A.M.)
| | - Conor McClenaghan
- Department of Cell Biology and Physiology (J.G., C.M.C., C.G.N.), Center for the Investigation of Membrane Excitability Diseases (J.G., C.M.C., D.K.G., C.G.N.), and Division of Genetics and Genomic Medicine, Department of Pediatrics (D.K.G.), Washington University in St. Louis, St. Louis, Missouri; and Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio (K.A.M.)
| | - Kenneth A Matreyek
- Department of Cell Biology and Physiology (J.G., C.M.C., C.G.N.), Center for the Investigation of Membrane Excitability Diseases (J.G., C.M.C., D.K.G., C.G.N.), and Division of Genetics and Genomic Medicine, Department of Pediatrics (D.K.G.), Washington University in St. Louis, St. Louis, Missouri; and Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio (K.A.M.)
| | - Dorothy K Grange
- Department of Cell Biology and Physiology (J.G., C.M.C., C.G.N.), Center for the Investigation of Membrane Excitability Diseases (J.G., C.M.C., D.K.G., C.G.N.), and Division of Genetics and Genomic Medicine, Department of Pediatrics (D.K.G.), Washington University in St. Louis, St. Louis, Missouri; and Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio (K.A.M.)
| | - Colin G Nichols
- Department of Cell Biology and Physiology (J.G., C.M.C., C.G.N.), Center for the Investigation of Membrane Excitability Diseases (J.G., C.M.C., D.K.G., C.G.N.), and Division of Genetics and Genomic Medicine, Department of Pediatrics (D.K.G.), Washington University in St. Louis, St. Louis, Missouri; and Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio (K.A.M.)
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Hanson A, McClenaghan C, Weng KC, Colijn S, Stratman AN, Halabi CM, Grange DK, Silva JR, Nichols CG. Electrophysiology of human iPSC-derived vascular smooth muscle cells and cell autonomous consequences of Cantu Syndrome mutations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.29.547088. [PMID: 37425756 PMCID: PMC10327170 DOI: 10.1101/2023.06.29.547088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Objective Cantu Syndrome (CS), a multisystem disease with a complex cardiovascular phenotype, is caused by GoF variants in the Kir6.1/SUR2 subunits of ATP-sensitive potassium (K ATP ) channels, and is characterized by low systemic vascular resistance, as well as tortuous, dilated vessels, and decreased pulse-wave velocity. Thus, CS vascular dysfunction is multifactorial, with distinct hypomyotonic and hyperelastic components. To dissect whether such complexities arise cell-autonomously within vascular smooth muscle cells (VSMCs), or as secondary responses to the pathophysiological milieu, we assessed electrical properties and gene expression in human induced pluripotent stem cell-derived VSMCs (hiPSC-VSMCs), differentiated from control and CS patient-derived hiPSCs, and in native mouse control and CS VSMCs. Approach and Results Whole-cell voltage-clamp of isolated aortic and mesenteric VSMCs isolated from wild type (WT) and Kir6.1[V65M] (CS) mice revealed no difference in voltage-gated K + (K v ) or Ca 2+ currents. K v and Ca 2+ currents were also not different between validated hiPSC-VSMCs differentiated from control and CS patient-derived hiPSCs. Pinacidil-sensitive K ATP currents in control hiPSC-VSMCs were consistent with those in WT mouse VSMCs, and were considerably larger in CS hiPSC-VSMCs. Consistent with lack of any compensatory modulation of other currents, this resulted in membrane hyperpolarization, explaining the hypomyotonic basis of CS vasculopathy. Increased compliance and dilation in isolated CS mouse aortae, was associated with increased elastin mRNA expression. This was consistent with higher levels of elastin mRNA in CS hiPSC-VSMCs, suggesting that the hyperelastic component of CS vasculopathy is a cell-autonomous consequence of vascular K ATP GoF. Conclusions The results show that hiPSC-VSMCs reiterate expression of the same major ion currents as primary VSMCs, validating the use of these cells to study vascular disease. The results further indicate that both the hypomyotonic and hyperelastic components of CS vasculopathy are cell-autonomous phenomena driven by K ATP overactivity within VSMCs.
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Scala R, Maqoud F, McClenaghan C, Harter TM, Perrone MG, Scilimati A, Nichols CG, Tricarico D. Zoledronic Acid Blocks Overactive Kir6.1/SUR2-Dependent K ATP Channels in Skeletal Muscle and Osteoblasts in a Murine Model of Cantú Syndrome. Cells 2023; 12:928. [PMID: 36980269 PMCID: PMC10047381 DOI: 10.3390/cells12060928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/24/2023] [Accepted: 03/11/2023] [Indexed: 03/22/2023] Open
Abstract
Cantú syndrome (CS) is caused by the gain of function mutations in the ABCC9 and KCNJ8 genes encoding, respectively, for the sulfonylureas receptor type 2 (SUR2) and the inwardly rectifier potassium channel 6.1 (Kir6.1) of the ATP-sensitive potassium (KATP) channels. CS is a multi-organ condition with a cardiovascular phenotype, neuromuscular symptoms, and skeletal malformations. Glibenclamide has been proposed for use in CS, but even in animals, the drug is incompletely effective against severe mutations, including the Kir6.1wt/V65M. Patch-clamp experiments showed that zoledronic acid (ZOL) fully reduced the whole-cell KATP currents in bone calvaria cells from wild type (WT/WT) and heterozygous Kir6.1wt/V65MCS mice, with IC50 for ZOL block < 1 nM in each case. ZOL fully reduced KATP current in excised patches in skeletal muscle fibers in WT/WT and CS mice, with IC50 of 100 nM in each case. Interestingly, KATP currents in the bone of heterozygous SUR2wt/A478V mice were less sensitive to ZOL inhibition, showing an IC50 of ~500 nM and a slope of ~0.3. In homozygous SUR2A478V/A478V cells, ZOL failed to fully inhibit the KATP currents, causing only ~35% inhibition at 100 μM, but was responsive to glibenclamide. ZOL reduced the KATP currents in Kir6.1wt/VMCS mice in both skeletal muscle and bone cells but was not effective in the SUR2[A478V] mice fibers. These data indicate a subunit specificity of ZOL action that is important for appropriate CS therapies.
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Affiliation(s)
- Rosa Scala
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Fatima Maqoud
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Conor McClenaghan
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA
| | - Theresa M. Harter
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA
| | - Maria Grazia Perrone
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Antonio Scilimati
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
| | - Colin G. Nichols
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA
| | - Domenico Tricarico
- Sections of Pharmacology, Medicinal Chemistry, Department of Pharmacy—Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy
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Gao J, McClenaghan C, Christiaans I, Alders M, van Duinen K, van Haelst MM, van Haaften G, Nichols CG. Lymphedema as first clinical presentation of Cantu Syndrome: reversed phenotyping after identification of gain-of-function variant in ABCC9. Eur J Hum Genet 2023; 31:188-194. [PMID: 36336713 PMCID: PMC9905590 DOI: 10.1038/s41431-022-01210-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 08/16/2022] [Accepted: 09/30/2022] [Indexed: 11/09/2022] Open
Abstract
Cantu Syndrome (CS), [OMIM #239850] is characterized by hypertrichosis, osteochondrodysplasia, and cardiomegaly. CS is caused by gain-of-function (GOF) variants in the KCNJ8 or ABCC9 genes that encode pore-forming Kir6.1 and regulatory SUR2 subunits of ATP-sensitive potassium (KATP) channels. Many subjects with CS also present with the complication of lymphedema. A previously uncharacterized, heterozygous ABCC9 variant, p.(Leu1055_Glu1058delinsPro), termed indel1055, was identified in an individual diagnosed with idiopathic lymphedema. The variant was introduced into the equivalent position of rat SUR2A, and inside-out patches were used to characterize the KATP channels formed by Kir6.2 and WT or mutant SUR2A subunits coexpressed in Cosm6 cells. The indel1055 variant causes gain-of-function of the channel, with an increase of the IC50 for ATP inhibition compared to WT. Retrospective consideration of this individual reveals clear features of Cantu Syndrome. An additional heterozygous ABCC9 variant, p.(Ile419Thr), was identified in a second individual diagnosed with lymphedema. In this case, there were no additional features consistent with CS, and the properties of p.(Ile416Thr) (the corresponding mutation in rat SUR2A)--containing channels were not different from WT. This proof-of-principle study shows that idiopathic lymphedema may actually be a first presentation of otherwise unrecognized Cantu Syndrome, but molecular phenotyping of identified variants is necessary to confirm relevance.
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Affiliation(s)
- Jian Gao
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, MO, USA
| | - Conor McClenaghan
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, MO, USA
| | - Imke Christiaans
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marielle Alders
- University of Amsterdam, Department of Human Genetics, Meibergdreef 9, Amsterdam, The Netherlands
| | - Kirsten van Duinen
- Department of Dermatology, Nij Smellinghe Hospital, Drachten, The Netherlands
| | - Mieke M van Haelst
- University of Amsterdam, Department of Human Genetics, Meibergdreef 9, Amsterdam, The Netherlands.
- Departments of Pediatrics, Amsterdam University Medical Centers, Amsterdam, The Netherlands.
- Emma Center for Personalized Medicine, Amsterdam University Medical Centers, Amsterdam, The Netherlands.
| | - Gijs van Haaften
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Colin G Nichols
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St. Louis, St. Louis, MO, USA.
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Crespo-García T, Rubio-Alarcón M, Cámara-Checa A, Dago M, Rapún J, Nieto-Marín P, Marín M, Cebrián J, Tamargo J, Delpón E, Caballero R. A Cantú syndrome mutation produces dual effects on KATP channels by disrupting ankyrin B regulation. J Gen Physiol 2022; 155:213613. [PMID: 36287534 PMCID: PMC9614705 DOI: 10.1085/jgp.202112995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/09/2022] [Accepted: 10/04/2022] [Indexed: 02/01/2023] Open
Abstract
ATP-sensitive potassium (KATP) channels composed of Kir6.x and sulfonylurea receptor (SURs) subunits couple cellular metabolism to electrical activity. Cantú syndrome (CS) is a rare disease caused by mutations in the genes encoding Kir6.1 (KCNJ8) and SUR2A (ABCC9) that produce KATP channel hyperactivity due to a reduced channel block by physiological ATP concentrations. We functionally characterized the p.S1054Y SUR2A mutation identified in two CS carriers, who exhibited a mild phenotype although the mutation was predicted as highly pathogenic. We recorded macroscopic and single-channel currents in CHO and HEK-293 cells and measured the membrane expression of the channel subunits by biotinylation assays in HEK-293 cells. The mutation increased basal whole-cell current density and at the single-channel level, it augmented opening frequency, slope conductance, and open probability (Po), and promoted the appearance of multiple conductance levels. p.S1054Y also reduced Kir6.2 and SUR2A expression specifically at the membrane. Overexpression of ankyrin B (AnkB) prevented these gain- and loss-of-function effects, as well as the p.S1054Y-induced reduction of ATP inhibition of currents measured in inside-out macropatches. Yeast two-hybrid assays suggested that SUR2A WT and AnkB interact, while p.S1054Y interaction with AnkB is decreased. The p.E322K Kir6.2 mutation, which prevents AnkB binding to Kir6.2, produced similar biophysical alterations than p.S1054Y. Our results are the first demonstration of a CS mutation whose functional consequences involve the disruption of AnkB effects on KATP channels providing a novel mechanism by which CS mutations can reduce ATP block. Furthermore, they may help explain the mild phenotype associated with this mutation.
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Affiliation(s)
- Teresa Crespo-García
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Marcos Rubio-Alarcón
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Anabel Cámara-Checa
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - María Dago
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Josu Rapún
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Paloma Nieto-Marín
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - María Marín
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Jorge Cebrián
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Juan Tamargo
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
| | - Eva Delpón
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain,Correspondence to Eva Delpón:
| | - Ricardo Caballero
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, Madrid, Spain,Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Madrid, Spain
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McClenaghan C, Nichols CG. Kir6.1 and SUR2B in Cantú syndrome. Am J Physiol Cell Physiol 2022; 323:C920-C935. [PMID: 35876283 PMCID: PMC9467476 DOI: 10.1152/ajpcell.00154.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/07/2022] [Accepted: 07/07/2022] [Indexed: 12/25/2022]
Abstract
Kir6.1 and SUR2 are subunits of ATP-sensitive potassium (KATP) channels expressed in a wide range of tissues. Extensive study has implicated roles of these channel subunits in diverse physiological functions. Together they generate the predominant KATP conductance in vascular smooth muscle and are the target of vasodilatory drugs. Roles for Kir6.1/SUR2 dysfunction in disease have been suggested based on studies of animal models and human genetic discoveries. In recent years, it has become clear that gain-of-function (GoF) mutations in both genes result in Cantú syndrome (CS)-a complex, multisystem disorder. There is currently no targeted therapy for CS, but studies of mouse models of the disease reveal that pharmacological reversibility of cardiovascular and gastrointestinal pathologies can be achieved by administration of the KATP channel inhibitor, glibenclamide. Here we review the function, structure, and physiological and pathological roles of Kir6.1/SUR2B channels, with a focus on CS. Recent studies have led to much improved understanding of the underlying pathologies and the potential for treatment, but important questions remain: Can the study of genetically defined CS reveal new insights into Kir6.1/SUR2 function? Do these reveal new pathophysiological mechanisms that may be important in more common diseases? And is our pharmacological armory adequately stocked?
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Affiliation(s)
- Conor McClenaghan
- Department of Cell Biology and Physiology, Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St. Louis, Missouri
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St. Louis, Missouri
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Lin CH, Lin YC, Yang SB, Chen PC. Carbamazepine promotes surface expression of mutant Kir6.2-A28V ATP-sensitive potassium channels by modulating Golgi retention and autophagy. J Biol Chem 2022; 298:101904. [PMID: 35398096 PMCID: PMC9065613 DOI: 10.1016/j.jbc.2022.101904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 03/25/2022] [Accepted: 03/27/2022] [Indexed: 11/21/2022] Open
Abstract
Pancreatic β-cells express ATP-sensitive potassium (KATP) channels, consisting of octamer complexes containing four sulfonylurea receptor 1 (SUR1) and four Kir6.2 subunits. Loss of KATP channel function causes persistent hyperinsulinemic hypoglycemia of infancy (PHHI), a rare but debilitating condition if not treated. We previously showed that the sodium-channel blocker carbamazepine (Carb) corrects KATP channel surface expression defects induced by PHHI-causing mutations in SUR1. In this study, we show that Carb treatment can also ameliorate the trafficking deficits associated with a recently discovered PHHI-causing mutation in Kir6.2 (Kir6.2-A28V). In human embryonic kidney 293 or INS-1 cells expressing this mutant KATP channel (SUR1 and Kir6.2-A28V), biotinylation and immunostaining assays revealed that Carb can increase surface expression of the mutant KATP channels. We further examined the subcellular distributions of mutant KATP channels before and after Carb treatment; without Carb treatment, we found that mutant KATP channels were aberrantly accumulated in the Golgi apparatus. However, after Carb treatment, coimmunoprecipitation of mutant KATP channels and Golgi marker GM130 was diminished, and KATP staining was also reduced in lysosomes. Intriguingly, Carb treatment also simultaneously increased autophagic flux and p62 accumulation, suggesting that autophagy-dependent degradation of the mutant channel was not only stimulated but also interrupted. In summary, our data suggest that surface expression of Kir6.2-A28V KATP channels is rescued by Carb treatment via promotion of mutant KATP channel exit from the Golgi apparatus and reduction of autophagy-mediated protein degradation.
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Munjal NS, Sapra D, Parthasarathi KTS, Goyal A, Pandey A, Banerjee M, Sharma J. Deciphering the Interactions of SARS-CoV-2 Proteins with Human Ion Channels Using Machine-Learning-Based Methods. Pathogens 2022; 11:pathogens11020259. [PMID: 35215201 PMCID: PMC8874499 DOI: 10.3390/pathogens11020259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/31/2022] [Accepted: 02/08/2022] [Indexed: 01/04/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is accountable for the protracted COVID-19 pandemic. Its high transmission rate and pathogenicity led to health emergencies and economic crisis. Recent studies pertaining to the understanding of the molecular pathogenesis of SARS-CoV-2 infection exhibited the indispensable role of ion channels in viral infection inside the host. Moreover, machine learning (ML)-based algorithms are providing a higher accuracy for host-SARS-CoV-2 protein–protein interactions (PPIs). In this study, PPIs of SARS-CoV-2 proteins with human ion channels (HICs) were trained on the PPI-MetaGO algorithm. PPI networks (PPINs) and a signaling pathway map of HICs with SARS-CoV-2 proteins were generated. Additionally, various U.S. food and drug administration (FDA)-approved drugs interacting with the potential HICs were identified. The PPIs were predicted with 82.71% accuracy, 84.09% precision, 84.09% sensitivity, 0.89 AUC-ROC, 65.17% Matthews correlation coefficient score (MCC) and 84.09% F1 score. Several host pathways were found to be altered, including calcium signaling and taste transduction pathway. Potential HICs could serve as an initial set to the experimentalists for further validation. The study also reinforces the drug repurposing approach for the development of host directed antiviral drugs that may provide a better therapeutic management strategy for infection caused by SARS-CoV-2.
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Affiliation(s)
- Nupur S. Munjal
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - Dikscha Sapra
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - K. T. Shreya Parthasarathi
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - Abhishek Goyal
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
| | - Akhilesh Pandey
- Center for Molecular Medicine, National Institute of Mental Health and Neurosciences (NIMHANS), Hosur Road, Bangalore 560029, India;
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Manidipa Banerjee
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India;
| | - Jyoti Sharma
- Institute of Bioinformatics, International Technology Park, Bangalore 560066, India; (N.S.M.); (D.S.); (K.T.S.P.); (A.G.)
- Manipal Academy of Higher Education (MAHE), Udupi 576104, India
- Correspondence:
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Fagnen C, Bannwarth L, Oubella I, Zuniga D, Haouz A, Forest E, Scala R, Bendahhou S, De Zorzi R, Perahia D, Vénien-Bryan C. Integrative Study of the Structural and Dynamical Properties of a KirBac3.1 Mutant: Functional Implication of a Highly Conserved Tryptophan in the Transmembrane Domain. Int J Mol Sci 2021; 23:335. [PMID: 35008764 PMCID: PMC8745282 DOI: 10.3390/ijms23010335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/18/2021] [Accepted: 12/23/2021] [Indexed: 12/02/2022] Open
Abstract
ATP-sensitive potassium (K-ATP) channels are ubiquitously expressed on the plasma membrane of cells in several organs, including the heart, pancreas, and brain, and they govern a wide range of physiological processes. In pancreatic β-cells, K-ATP channels composed of Kir6.2 and SUR1 play a key role in coupling blood glucose and insulin secretion. A tryptophan residue located at the cytosolic end of the transmembrane helix is highly conserved in eukaryote and prokaryote Kir channels. Any mutation on this amino acid causes a gain of function and neonatal diabetes mellitus. In this study, we have investigated the effect of mutation on this highly conserved residue on a KirBac channel (prokaryotic homolog of mammalian Kir6.2). We provide the crystal structure of the mutant KirBac3.1 W46R (equivalent to W68R in Kir6.2) and its conformational flexibility properties using HDX-MS. In addition, the detailed dynamical view of the mutant during the gating was investigated using the in silico method. Finally, functional assays have been performed. A comparison of important structural determinants for the gating mechanism between the wild type KirBac and the mutant W46R suggests interesting structural and dynamical clues and a mechanism of action of the mutation that leads to the gain of function.
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Affiliation(s)
- Charline Fagnen
- IMPMC, UMR 7590, CNRS, Muséum National d’Histoire Naturelle, Sorbonne Université, 75005 Paris, France; (C.F.); (L.B.); (I.O.); (D.Z.)
- Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure Paris-Saclay, 4 Ave. des Sciences, 91190 Gif-sur-Yvette, France;
| | - Ludovic Bannwarth
- IMPMC, UMR 7590, CNRS, Muséum National d’Histoire Naturelle, Sorbonne Université, 75005 Paris, France; (C.F.); (L.B.); (I.O.); (D.Z.)
| | - Iman Oubella
- IMPMC, UMR 7590, CNRS, Muséum National d’Histoire Naturelle, Sorbonne Université, 75005 Paris, France; (C.F.); (L.B.); (I.O.); (D.Z.)
| | - Dania Zuniga
- IMPMC, UMR 7590, CNRS, Muséum National d’Histoire Naturelle, Sorbonne Université, 75005 Paris, France; (C.F.); (L.B.); (I.O.); (D.Z.)
| | - Ahmed Haouz
- Institut Pasteur, C2RT-Plate-Forme de Cristallographie CNRS-UMR3528, 75724 Paris, France;
| | - Eric Forest
- CNRS, IBS, CEA, University Grenoble Alpes, 38044 Grenoble, France;
| | - Rosa Scala
- CNRS UMR7370, LP2M, Labex ICST, Faculté de Médecine, University Côte d’Azur, 06560 Nice, France; (R.S.); (S.B.)
| | - Saïd Bendahhou
- CNRS UMR7370, LP2M, Labex ICST, Faculté de Médecine, University Côte d’Azur, 06560 Nice, France; (R.S.); (S.B.)
| | - Rita De Zorzi
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Licio Giorgeri 1, 34127 Trieste, Italy;
| | - David Perahia
- Laboratoire de Biologie et Pharmacologie Appliquée, Ecole Normale Supérieure Paris-Saclay, 4 Ave. des Sciences, 91190 Gif-sur-Yvette, France;
| | - Catherine Vénien-Bryan
- IMPMC, UMR 7590, CNRS, Muséum National d’Histoire Naturelle, Sorbonne Université, 75005 Paris, France; (C.F.); (L.B.); (I.O.); (D.Z.)
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10
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Singareddy SS, Roessler HI, McClenaghan C, Ikle JM, Tryon RC, van Haaften G, Nichols CG. ATP-sensitive potassium channels in zebrafish cardiac and vascular smooth muscle. J Physiol 2021; 600:299-312. [PMID: 34820842 DOI: 10.1113/jp282157] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/18/2021] [Indexed: 12/12/2022] Open
Abstract
ATP-sensitive potassium channels (KATP channels) are hetero-octameric nucleotide-gated ion channels that couple cellular metabolism to excitability in various tissues. In the heart, KATP channels are activated during ischaemia and potentially during adrenergic stimulation. In the vasculature, they are normally active at a low level, reducing vascular tone, but the ubiquitous nature of these channels leads to complex and poorly understood channelopathies as a result of gain- or loss-of-function mutations. Zebrafish (ZF) models of these channelopathies may provide insights to the link between molecular dysfunction and complex pathophysiology, but this requires understanding the tissue dependence of channel activity and subunit specificity. Thus far, direct analysis of ZF KATP expression and functional properties has only been performed in pancreatic β-cells. Using a comprehensive combination of genetically modified fish, electrophysiology and gene expression analysis, we demonstrate that ZF cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure and metabolic sensitivity to their mammalian counterparts. However, in contrast to mammalian cardiovascular KATP channels, ZF channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. The results provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantú syndrome and ABCC9-related Intellectual Disability and Myopathy syndrome. KEY POINTS: Zebrafish cardiac myocytes (CM) and vascular smooth muscle (VSM) express functional KATP channels of similar subunit composition, structure and metabolic sensitivity to their mammalian counterparts. In contrast to mammalian cardiovascular KATP channels, zebrafish channels are insensitive to potassium channel opener drugs (pinacidil, minoxidil) in both chambers of the heart and in VSM. We provide a first characterization of the molecular properties of fish KATP channels and validate the use of such genetically modified fish as models of human Cantú syndrome and ABCC9-related Intellectual Disability and Myopathy syndrome.
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Affiliation(s)
- Soma S Singareddy
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Helen I Roessler
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Conor McClenaghan
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Jennifer M Ikle
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Robert C Tryon
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
| | - Gijs van Haaften
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Colin G Nichols
- Department of Cell Biology and Physiology and Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA
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11
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Vascular K ATP channel structural dynamics reveal regulatory mechanism by Mg-nucleotides. Proc Natl Acad Sci U S A 2021; 118:2109441118. [PMID: 34711681 PMCID: PMC8694068 DOI: 10.1073/pnas.2109441118] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/30/2021] [Indexed: 11/24/2022] Open
Abstract
Vascular KATP channels formed by the potassium channel Kir6.1 and its regulatory protein SUR2B maintain blood pressure in the physiological range. Overactivity of the channel due to genetic mutations in either Kir6.1 or SUR2B causes severe cardiovascular pathologies known as Cantú syndrome. The cryogenic electron microscopy structures of the vascular KATP channel reported here show multiple, dynamically related conformations of the regulatory subunit SUR2B. Molecular dynamics simulations reveal the negatively charged ED-domain in SUR2B, a stretch of 15 glutamate (E) and aspartate (D) residues not previously resolved, play a key MgADP-dependent role in mediating interactions at the interface between the SUR2B and Kir6.1 subunits. Our findings provide a mechanistic understanding of how channel activity is regulated by intracellular MgADP. Vascular tone is dependent on smooth muscle KATP channels comprising pore-forming Kir6.1 and regulatory SUR2B subunits, in which mutations cause Cantú syndrome. Unique among KATP isoforms, they lack spontaneous activity and require Mg-nucleotides for activation. Structural mechanisms underlying these properties are unknown. Here, we determined cryogenic electron microscopy structures of vascular KATP channels bound to inhibitory ATP and glibenclamide, which differ informatively from similarly determined pancreatic KATP channel isoform (Kir6.2/SUR1). Unlike SUR1, SUR2B subunits adopt distinct rotational “propeller” and “quatrefoil” geometries surrounding their Kir6.1 core. The glutamate/aspartate-rich linker connecting the two halves of the SUR-ABC core is observed in a quatrefoil-like conformation. Molecular dynamics simulations reveal MgADP-dependent dynamic tripartite interactions between this linker, SUR2B, and Kir6.1. The structures captured implicate a progression of intermediate states between MgADP-free inactivated, and MgADP-bound activated conformations wherein the glutamate/aspartate-rich linker participates as mobile autoinhibitory domain, suggesting a conformational pathway toward KATP channel activation.
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12
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Maqoud F, Scala R, Tragni V, Pierri CL, Perrone MG, Scilimati A, Tricarico D. Zoledronic Acid as a Novel Dual Blocker of KIR6.1/2-SUR2 Subunits of ATP-Sensitive K + Channels: Role in the Adverse Drug Reactions. Pharmaceutics 2021; 13:pharmaceutics13091350. [PMID: 34575427 PMCID: PMC8465290 DOI: 10.3390/pharmaceutics13091350] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/06/2021] [Accepted: 08/17/2021] [Indexed: 12/17/2022] Open
Abstract
Zoledronic acid (ZOL) is used as a bone-specific antiresorptive drug with antimyeloma effects. Adverse drug reactions (A.D.R.) are associated with ZOL-therapy, whose mechanics are unknown. ZOL is a nitrogen-containing molecule whose structure shows similarities with nucleotides, ligands of ATP-sensitive K+ (KATP) channels. We investigated the action of ZOL by performing in vitro patch-clamp experiments on native KATP channels in murine skeletal muscle fibers, bone cells, and recombinant subunits in cell lines, and by in silico docking the nucleotide site on KIR and SUR, as well as the glibenclamide site. ZOL fully inhibited the KATP currents recorded in excised macro-patches from Extensor digitorum longus (EDL) and Soleus (SOL) muscle fibers with an IC50 of 1.2 ± 1.4 × 10−6 and 2.1 ± 3.7 × 10−10 M, respectively, and the KATP currents recorded in cell-attached patches from primary long bone cells with an IC50 of 1.6 ± 2.8 × 10−10 M. ZOL fully inhibited a whole-cell KATP channel current of recombinant KIR6.1-SUR2B and KIR6.2-SUR2A subunits expressed in HEK293 cells with an IC50 of 3.9 ± 2.7 × 10−10 M and 7.1 ± 3.1 × 10−6 M, respectively. The rank order of potency in inhibiting the KATP currents was: KIR6.1-SUR2B/SOL-KATP/osteoblast-KATP > KIR6.2-SUR2A/EDL-KATP >>> KIR6.2-SUR1 and KIR6.1-SUR1. Docking investigation revealed that the drug binds to the ADP/ATP sites on KIR6.1/2 and SUR2A/B and on the sulfonylureas site showing low binding energy <6 Kcal/mol for the KIR6.1/2-SUR2 subunits vs. the <4 Kcal/mol for the KIR6.2-SUR1. The IC50 of ZOL to inhibit the KIR6.1/2-SUR2A/B channels were correlated with its musculoskeletal and cardiovascular risks. We first showed that ZOL blocks at subnanomolar concentration musculoskeletal KATP channels and cardiac and vascular KIR6.2/1-SUR2 channels.
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Affiliation(s)
- Fatima Maqoud
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy; (F.M.); (R.S.)
| | - Rosa Scala
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy; (F.M.); (R.S.)
| | - Vincenzo Tragni
- Laboratory of Biochemistry, Structural and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy; (V.T.); (C.L.P.)
| | - Ciro Leonardo Pierri
- Laboratory of Biochemistry, Structural and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via Orabona 4, 70125 Bari, Italy; (V.T.); (C.L.P.)
- BROWSer S.r.l., University of Bari “Aldo Moro”, Via E. Orabona, 4, 70126 Bari, Italy
| | - Maria Grazia Perrone
- Medicinal Chemistry Section, Department of Pharmacy-Pharmaceutical Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy; (M.G.P.); (A.S.)
| | - Antonio Scilimati
- Medicinal Chemistry Section, Department of Pharmacy-Pharmaceutical Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy; (M.G.P.); (A.S.)
| | - Domenico Tricarico
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy; (F.M.); (R.S.)
- Correspondence:
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13
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Weng J, Wang A, Zhang D, Liao C, Li G. A double bilayer to study the nonequilibrium environmental response of GIRK2 in complex states. Phys Chem Chem Phys 2021; 23:15784-15795. [PMID: 34286758 DOI: 10.1039/d1cp01785c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels play essential roles in electrical signaling in neurons and muscle cells. Nonequilibrium environments provide crucial driving forces behind many cellular events. Here, we apply the antiparallel alignment double bilayer model to study GIRK2 in response to the time-dependent membrane potential. Using molecular dynamics and umbrella sampling, we examined the time-dependent environmental impact on the ion conduction, energy basis, and primary motions of GIRK2 in different complex states with phosphatidylinositol-4,5-bisphosphate (PIP2) and G-protein βγ subunits (Gβγ). The antiparallel alignment double bilayer model enables us to study the transport performance in inward and outward K+ and mixed K+ and Na+. We obtained the recoverable discharge process of GIRK2 complexed with both PIP2 and Gβγ, compared with occasional conduction under PIP2-only regulation. Calculations of potential of mean force suggest different regulation by the helix bundle crossing (HBC) gate and G-loop gate regarding different complex states and under a membrane potential. In a nonequilibrium environment, distinct functional rocking motions of GIRK2 were identified under strengthened correlations between the transmembrane helices and downstream cytoplasmic domains with binding of PIP2, cations, and Gβγ. The findings suggest the potential domain motions and dynamics associated with a nonequilibrium environment and highlight the application of the antiparallel alignment double bilayer model to investigate factors in an asymmetric environment.
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Affiliation(s)
- Junben Weng
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China. and University of Chinese Academy of Sciences, Beijing, China
| | - Anhui Wang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Dinglin Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China. and University of Chinese Academy of Sciences, Beijing, China
| | - Chenyi Liao
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Guohui Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
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14
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Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
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15
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Scala R, Maqoud F, Zizzo N, Passantino G, Mele A, Camerino GM, McClenaghan C, Harter TM, Nichols CG, Tricarico D. Consequences of SUR2[A478V] Mutation in Skeletal Muscle of Murine Model of Cantu Syndrome. Cells 2021; 10:cells10071791. [PMID: 34359961 PMCID: PMC8307364 DOI: 10.3390/cells10071791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 12/18/2022] Open
Abstract
(1) Background: Cantu syndrome (CS) arises from gain-of-function (GOF) mutations in the ABCC9 and KCNJ8 genes, which encode ATP-sensitive K+ (KATP) channel subunits SUR2 and Kir6.1, respectively. Most CS patients have mutations in SUR2, the major component of skeletal muscle KATP, but the consequences of SUR2 GOF in skeletal muscle are unknown. (2) Methods: We performed in vivo and ex vivo characterization of skeletal muscle in heterozygous SUR2[A478V] (SUR2wt/AV) and homozygous SUR2[A478V] (SUR2AV/AV) CS mice. (3) Results: In SUR2wt/AV and SUR2AV/AV mice, forelimb strength and diaphragm amplitude movement were reduced; muscle echodensity was enhanced. KATP channel currents recorded in Flexor digitorum brevis fibers showed reduced MgATP-sensitivity in SUR2wt/AV, dramatically so in SUR2AV/AV mice; IC50 for MgATP inhibition of KATP currents were 1.9 ± 0.5 × 10−5 M in SUR2wt/AV and 8.6 ± 0.4 × 10−6 M in WT mice and was not measurable in SUR2AV/AV. A slight rightward shift of sensitivity to inhibition by glibenclamide was detected in SUR2AV/AV mice. Histopathological and qPCR analysis revealed atrophy of soleus and tibialis anterior muscles and up-regulation of atrogin-1 and MuRF1 mRNA in CS mice. (4) Conclusions: SUR2[A478V] “knock-in” mutation in mice impairs KATP channel modulation by MgATP, markedly so in SUR2AV/AV, with atrophy and non-inflammatory edema in different skeletal muscle phenotypes.
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Affiliation(s)
- Rosa Scala
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (R.S.); (F.M.); (A.M.); (G.M.C.)
| | - Fatima Maqoud
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (R.S.); (F.M.); (A.M.); (G.M.C.)
| | - Nicola Zizzo
- Section of Veterinary Pathology and Comparative Oncology, Department of Veterinary Medicine, University of Bari “Aldo Moro”, 70121 Bari, Italy; (N.Z.); (G.P.)
| | - Giuseppe Passantino
- Section of Veterinary Pathology and Comparative Oncology, Department of Veterinary Medicine, University of Bari “Aldo Moro”, 70121 Bari, Italy; (N.Z.); (G.P.)
| | - Antonietta Mele
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (R.S.); (F.M.); (A.M.); (G.M.C.)
| | - Giulia Maria Camerino
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (R.S.); (F.M.); (A.M.); (G.M.C.)
| | - Conor McClenaghan
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA; (C.M.); (T.M.H.); (C.G.N.)
| | - Theresa M. Harter
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA; (C.M.); (T.M.H.); (C.G.N.)
| | - Colin G. Nichols
- Center for the Investigation of Membrane Excitability Diseases, Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110-1010, USA; (C.M.); (T.M.H.); (C.G.N.)
| | - Domenico Tricarico
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (R.S.); (F.M.); (A.M.); (G.M.C.)
- Correspondence:
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16
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Zhang H, Hanson A, de Almeida TS, Emfinger C, McClenaghan C, Harter T, Yan Z, Cooper PE, Brown GS, Arakel EC, Mecham RP, Kovacs A, Halabi CM, Schwappach B, Remedi MS, Nichols CG. Complex consequences of Cantu syndrome SUR2 variant R1154Q in genetically modified mice. JCI Insight 2021; 6:145934. [PMID: 33529173 PMCID: PMC8021106 DOI: 10.1172/jci.insight.145934] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/27/2021] [Indexed: 01/10/2023] Open
Abstract
Cantu syndrome (CS) is caused by gain-of-function (GOF) mutations in pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) ATP-sensitive potassium (KATP) channel subunits, the most common mutations being SUR2[R1154Q] and SUR2[R1154W], carried by approximately 30% of patients. We used CRISPR/Cas9 genome engineering to introduce the equivalent of the human SUR2[R1154Q] mutation into the mouse ABCC9 gene. Along with minimal CS disease features, R1154Q cardiomyocytes and vascular smooth muscle showed much lower KATP current density and pinacidil activation than WT cells. Almost complete loss of SUR2-dependent protein and KATP in homozygous R1154Q ventricles revealed underlying diazoxide-sensitive SUR1-dependent KATP channel activity. Surprisingly, sequencing of SUR2 cDNA revealed 2 distinct transcripts, one encoding full-length SUR2 protein; and the other with an in-frame deletion of 93 bases (corresponding to 31 amino acids encoded by exon 28) that was present in approximately 40% and approximately 90% of transcripts from hetero- and homozygous R1154Q tissues, respectively. Recombinant expression of SUR2A protein lacking exon 28 resulted in nonfunctional channels. CS tissue from SUR2[R1154Q] mice and human induced pluripotent stem cell-derived (hiPSC-derived) cardiomyocytes showed only full-length SUR2 transcripts, although further studies will be required in order to fully test whether SUR2[R1154Q] or other CS mutations might result in aberrant splicing and variable expressivity of disease features in human CS.
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Affiliation(s)
- Haixia Zhang
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Alex Hanson
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Tobias Scherf de Almeida
- Department of Molecular Biology, Center for Biochemistry and Molecular Cell Biology, Heart Research Center Göttingen, University Medicine Göttingen, Göttingen, Germany
| | - Christopher Emfinger
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Conor McClenaghan
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Theresa Harter
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Zihan Yan
- Center for the Investigation of Membrane Excitability Diseases and.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.,Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research
| | - Paige E Cooper
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - G Schuyler Brown
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Eric C Arakel
- Department of Molecular Biology, Center for Biochemistry and Molecular Cell Biology, Heart Research Center Göttingen, University Medicine Göttingen, Göttingen, Germany
| | - Robert P Mecham
- Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | | | - Carmen M Halabi
- Department of Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Blanche Schwappach
- Department of Molecular Biology, Center for Biochemistry and Molecular Cell Biology, Heart Research Center Göttingen, University Medicine Göttingen, Göttingen, Germany
| | - Maria S Remedi
- Center for the Investigation of Membrane Excitability Diseases and.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | - Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases and.,Department of Cell Biology and Physiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
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17
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Scala R, Maqoud F, Zizzo N, Mele A, Camerino GM, Zito FA, Ranieri G, McClenaghan C, Harter TM, Nichols CG, Tricarico D. Pathophysiological Consequences of KATP Channel Overactivity and Pharmacological Response to Glibenclamide in Skeletal Muscle of a Murine Model of Cantù Syndrome. Front Pharmacol 2020; 11:604885. [PMID: 33329006 PMCID: PMC7734337 DOI: 10.3389/fphar.2020.604885] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/03/2020] [Indexed: 12/11/2022] Open
Abstract
Cantù syndrome (CS) arises from mutations in ABCC9 and KCNJ8 genes that lead to gain of function (GOF) of ATP-sensitive potassium (KATP) channels containing SUR2A and Kir6.1 subunits, respectively, of KATP channels. Pathological consequences of CS have been reported for cardiac and smooth muscle cells but consequences in skeletal muscle are unknown. Children with CS show muscle hypotonia and adult manifest fatigability. We analyzed muscle properties of Kir6.1[V65M] CS mice, by measurements of forelimb strength and ultrasonography of hind-limb muscles, as well as assessing KATP channel properties in native Flexor digitorum brevis (FDB) and Soleus (SOL) fibers by the patch-clamp technique in parallel with histopathological, immunohistochemical and Polymerase Chain Reaction (PCR) analysis. Forelimb strength was lower in Kir6.1wt/VM mice than in WT mice. Also, a significant enhancement of echodensity was observed in hind-limb muscles of Kir6.1wt/VM mice relative to WT, suggesting the presence of fibrous tissue. There was a higher KATP channel current amplitude in Kir6.1wt/VM FDB fibers relative to WT and a reduced response to glibenclamide. The IC50 of glibenclamide to block KATP channels in FDB fibers was 1.3 ± 0.2 × 10−7 M in WT and 1.2 ± 0.1 × 10−6 M in Kir6.1wt/VM mice, respectively; and it was 1.2 ± 0.4 × 10−7 M in SOL WT fibers but not measurable in Kir6.1wt/VM fibers. The sensitivity of the KATP channel to MgATP was not modified in Kir6.1wt/VM fibers. Histopathological/immunohistochemical analysis of SOL revealed degeneration plus regressive-necrotic lesions with regeneration, and up-regulation of Atrogin-1, MuRF1, and BNIP3 mRNA/proteins in Kir6.1wt/VM mice. Kir6.1wt/VM mutation in skeletal muscle leads to changes of the KATP channel response to glibenclamide in FDB and SOL fibers, and it is associated with histopathological and gene expression changes in slow-twitch muscle, suggesting marked atrophy and autophagy.
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Affiliation(s)
- Rosa Scala
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Fatima Maqoud
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Nicola Zizzo
- Section of Veterinary Pathology and Comparative Oncology, Department of Veterinary Medicine, University of Bari "Aldo Moro", Valenzano, Italy
| | - Antonietta Mele
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Giulia Maria Camerino
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari "Aldo Moro", Bari, Italy
| | - Francesco Alfredo Zito
- Interventional and Medical Oncology Unit, Department of Pathology National Cancer Research Centre, IRCCS Istituto Tumori Giovanni Paolo II, Bari, Italy
| | - Girolamo Ranieri
- Interventional and Medical Oncology Unit, Department of Pathology National Cancer Research Centre, IRCCS Istituto Tumori Giovanni Paolo II, Bari, Italy
| | - Conor McClenaghan
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, United States
| | - Theresa M Harter
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, United States
| | - Colin G Nichols
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO, United States
| | - Domenico Tricarico
- Section of Pharmacology, Department of Pharmacy-Pharmaceutical Sciences, University of Bari "Aldo Moro", Bari, Italy
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18
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York NW, Parker H, Xie Z, Tyus D, Waheed MA, Yan Z, Grange DK, Remedi MS, England SK, Hu H, Nichols CG. Kir6.1- and SUR2-dependent KATP over-activity disrupts intestinal motility in murine models of Cantu Syndrome. JCI Insight 2020; 5:141443. [PMID: 33170808 PMCID: PMC7714409 DOI: 10.1172/jci.insight.141443] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 10/28/2020] [Indexed: 11/17/2022] Open
Abstract
Cantύ Syndrome (CS), caused by gain-of-function (GOF) mutations in pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) ATP-sensitive potassium (KATP) channel subunit genes, is frequently accompanied by gastrointestinal (GI) dysmotility, and we describe one CS patient who required an implanted intestinal irrigation system for successful stooling. We used gene-modified mice to assess the underlying KATP channel subunits in gut smooth muscle, and to model the consequences of altered KATP channels in CS gut. We show that Kir6.1/SUR2 subunits underlie smooth muscle KATP channels throughout the small intestine and colon. Knock-in mice, carrying human KCNJ8 and ABCC9 CS mutations in the endogenous loci, exhibit reduced intrinsic contractility throughout the intestine, resulting in death when weaned onto solid food in the most severely affected animals. Death is avoided by weaning onto a liquid gel diet, implicating intestinal insufficiency and bowel impaction as the underlying cause, and GI transit is normalized by treatment with the KATP inhibitor glibenclamide. We thus define the molecular basis of intestinal KATP channel activity, the mechanism by which overactivity results in GI insufficiency, and a viable approach to therapy.
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Affiliation(s)
- Nathaniel W York
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States of America
| | - Helen Parker
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States of America
| | - Zili Xie
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States of America
| | - David Tyus
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States of America
| | - Maham A Waheed
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States of America
| | - Zihan Yan
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States of America
| | - Dorothy K Grange
- Divison of Clinical Genetics, Washington University School of Medicine, St. Louis, United States of America
| | - Maria S Remedi
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States of America
| | - Sarah K England
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, United States of America
| | - Hongzhen Hu
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, United States of America
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States of America
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19
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McClenaghan C, Huang Y, Yan Z, Harter TM, Halabi CM, Chalk R, Kovacs A, van Haaften G, Remedi MS, Nichols CG. Glibenclamide reverses cardiovascular abnormalities of Cantu syndrome driven by KATP channel overactivity. J Clin Invest 2020; 130:1116-1121. [PMID: 31821173 DOI: 10.1172/jci130571] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 12/05/2019] [Indexed: 12/12/2022] Open
Abstract
Cantu syndrome (CS) is a complex disorder caused by gain-of-function (GoF) mutations in ABCC9 and KCNJ8, which encode the SUR2 and Kir6.1 subunits, respectively, of vascular smooth muscle (VSM) KATP channels. CS includes dilated vasculature, marked cardiac hypertrophy, and other cardiovascular abnormalities. There is currently no targeted therapy, and it is unknown whether cardiovascular features can be reversed once manifest. Using combined transgenic and pharmacological approaches in a knockin mouse model of CS, we have shown that reversal of vascular and cardiac phenotypes can be achieved by genetic downregulation of KATP channel activity specifically in VSM, and by chronic administration of the clinically used KATP channel inhibitor, glibenclamide. These findings demonstrate that VSM KATP channel GoF underlies CS cardiac enlargement and that CS-associated abnormalities are reversible, and provide evidence of in vivo efficacy of glibenclamide as a therapeutic agent in CS.
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Affiliation(s)
- Conor McClenaghan
- Center for the Investigation of Membrane Excitability Diseases.,Department of Cell Biology.,Department of Physiology
| | - Yan Huang
- Center for the Investigation of Membrane Excitability Diseases.,Department of Cell Biology.,Department of Physiology
| | - Zihan Yan
- Center for the Investigation of Membrane Excitability Diseases.,Division of Endocrinology, Department of Medicine, and
| | - Theresa M Harter
- Center for the Investigation of Membrane Excitability Diseases.,Department of Cell Biology.,Department of Physiology
| | - Carmen M Halabi
- Center for the Investigation of Membrane Excitability Diseases.,Division of Nephrology, Department of Pediatrics, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Rod Chalk
- Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom
| | - Attila Kovacs
- Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Gijs van Haaften
- Center for Molecular Medicine, Department of Genetics, University Medical Center Utrecht, Utrecht, Netherlands
| | - Maria S Remedi
- Center for the Investigation of Membrane Excitability Diseases.,Division of Endocrinology, Department of Medicine, and
| | - Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases.,Department of Cell Biology.,Department of Physiology
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20
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Smeland MF, McClenaghan C, Roessler HI, Savelberg S, Hansen GÅM, Hjellnes H, Arntzen KA, Müller KI, Dybesland AR, Harter T, Sala-Rabanal M, Emfinger CH, Huang Y, Singareddy SS, Gunn J, Wozniak DF, Kovacs A, Massink M, Tessadori F, Kamel SM, Bakkers J, Remedi MS, Van Ghelue M, Nichols CG, van Haaften G. ABCC9-related Intellectual disability Myopathy Syndrome is a K ATP channelopathy with loss-of-function mutations in ABCC9. Nat Commun 2019; 10:4457. [PMID: 31575858 PMCID: PMC6773855 DOI: 10.1038/s41467-019-12428-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 08/30/2019] [Indexed: 11/30/2022] Open
Abstract
Mutations in genes encoding KATP channel subunits have been reported for pancreatic disorders and Cantú syndrome. Here, we report a syndrome in six patients from two families with a consistent phenotype of mild intellectual disability, similar facies, myopathy, and cerebral white matter hyperintensities, with cardiac systolic dysfunction present in the two oldest patients. Patients are homozygous for a splice-site mutation in ABCC9 (c.1320 + 1 G > A), which encodes the sulfonylurea receptor 2 (SUR2) subunit of KATP channels. This mutation results in an in-frame deletion of exon 8, which results in non-functional KATP channels in recombinant assays. SUR2 loss-of-function causes fatigability and cardiac dysfunction in mice, and reduced activity, cardiac dysfunction and ventricular enlargement in zebrafish. We term this channelopathy resulting from loss-of-function of SUR2-containing KATP channels ABCC9-related Intellectual disability Myopathy Syndrome (AIMS). The phenotype differs from Cantú syndrome, which is caused by gain-of-function ABCC9 mutations, reflecting the opposing consequences of KATP loss- versus gain-of-function.
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Affiliation(s)
- Marie F Smeland
- Department of Medical Genetics, University Hospital of North Norway, 9019, Tromsø, Norway.
| | - Conor McClenaghan
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO, 63110, USA
| | - Helen I Roessler
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Sanne Savelberg
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | | | - Helene Hjellnes
- Department of Medical Genetics, University Hospital of North Norway, 9019, Tromsø, Norway
| | - Kjell Arne Arntzen
- Department of Neurology, University Hospital of North Norway, 9019, Tromsø, Norway
- Department of Clinical Medicine, UiT-The Arctic University of Norway, 9019, Tromsø, Norway
- The National Neuromuscular Centre of Norway, University Hospital of North Norway, 9019, Tromsø, Norway
| | - Kai Ivar Müller
- Department of Neurology, University Hospital of North Norway, 9019, Tromsø, Norway
- Department of Clinical Medicine, UiT-The Arctic University of Norway, 9019, Tromsø, Norway
| | - Andreas Rosenberger Dybesland
- The National Neuromuscular Centre of Norway, University Hospital of North Norway, 9019, Tromsø, Norway
- Department of Physiotherapy, University Hospital of North Norway, 9019, Tromsø, Norway
| | - Theresa Harter
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO, 63110, USA
| | - Monica Sala-Rabanal
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO, 63110, USA
- Department of Anesthesiology, Washington University, St Louis, MO, 63110, USA
| | - Chris H Emfinger
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO, 63110, USA
| | - Yan Huang
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO, 63110, USA
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Soma S Singareddy
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO, 63110, USA
| | - Jamie Gunn
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - David F Wozniak
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Attila Kovacs
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Maarten Massink
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Federico Tessadori
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
- Hubrecht Institute-KNAW and UMC Utrecht, 3584 CT, Utrecht, the Netherlands
| | - Sarah M Kamel
- Hubrecht Institute-KNAW and UMC Utrecht, 3584 CT, Utrecht, the Netherlands
| | - Jeroen Bakkers
- Hubrecht Institute-KNAW and UMC Utrecht, 3584 CT, Utrecht, the Netherlands
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands
| | - Maria S Remedi
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University, St Louis, MO, 63110, USA
| | - Marijke Van Ghelue
- Department of Medical Genetics, University Hospital of North Norway, 9019, Tromsø, Norway
- Department of Medical Genetics, the Arctic University of Norway, 9019, Tromsø, Norway
| | - Colin G Nichols
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO, 63110, USA
| | - Gijs van Haaften
- Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, 3584 CX, Utrecht, the Netherlands.
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21
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McClenaghan C, Woo KV, Nichols CG. Pulmonary Hypertension and ATP-Sensitive Potassium Channels. Hypertension 2019; 74:14-22. [PMID: 31132951 DOI: 10.1161/hypertensionaha.119.12992] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Conor McClenaghan
- From the Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO (C.M., C.G.N.)
| | - Kel Vin Woo
- Department of Pediatrics, Division of Cardiology, Washington University School of Medicine, St Louis, MO (K.V.W.)
| | - Colin G Nichols
- From the Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO (C.M., C.G.N.)
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22
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Chen X, Garon A, Wieder M, Houtman MJC, Zangerl-Plessl EM, Langer T, van der Heyden MAG, Stary-Weinzinger A. Computational Identification of Novel Kir6 Channel Inhibitors. Front Pharmacol 2019; 10:549. [PMID: 31178728 PMCID: PMC6543810 DOI: 10.3389/fphar.2019.00549] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/01/2019] [Indexed: 12/25/2022] Open
Abstract
KATP channels consist of four Kir6.x pore-forming subunits and four regulatory sulfonylurea receptor (SUR) subunits. These channels couple the metabolic state of the cell to membrane excitability and play a key role in physiological processes such as insulin secretion in the pancreas, protection of cardiac muscle during ischemia and hypoxic vasodilation of arterial smooth muscle cells. Abnormal channel function resulting from inherited gain or loss-of-function mutations in either the Kir6.x and/or SUR subunits are associated with severe diseases such as neonatal diabetes, congenital hyperinsulinism, or Cantú syndrome (CS). CS is an ultra-rare genetic autosomal dominant disorder, caused by dominant gain-of-function mutations in SUR2A or Kir6.1 subunits. No specific pharmacotherapeutic treatment options are currently available for CS. Kir6 specific inhibitors could be beneficial for the development of novel drug therapies for CS, particular for mutations, which lack high affinity for sulfonylurea inhibitor glibenclamide. By applying a combination of computational methods including atomistic MD simulations, free energy calculations and pharmacophore modeling, we identified several novel Kir6.1 inhibitors, which might be possible candidates for drug repurposing. The in silico predictions were confirmed using inside/out patch-clamp analysis. Importantly, Cantú mutation C166S in Kir6.2 (equivalent to C176S in Kir6.1) and S1020P in SUR2A, retained high affinity toward the novel inhibitors. Summarizing, the inhibitors identified in this study might provide a starting point toward developing novel therapies for Cantú disease.
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Affiliation(s)
- Xingyu Chen
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Arthur Garon
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Marcus Wieder
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Marien J. C. Houtman
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
| | | | - Thierry Langer
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Marcel A. G. van der Heyden
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, Netherlands
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23
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Houtman MJC, Chen X, Qile M, Duran K, van Haaften G, Stary-Weinzinger A, van der Heyden MAG. Glibenclamide and HMR1098 normalize Cantú syndrome-associated gain-of-function currents. J Cell Mol Med 2019; 23:4962-4969. [PMID: 31119887 PMCID: PMC7346732 DOI: 10.1111/jcmm.14329] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 03/13/2019] [Accepted: 03/25/2019] [Indexed: 12/15/2022] Open
Abstract
Cantú syndrome (CS) is caused by dominant gain-of-function mutation in ATP-dependent potassium channels. Cellular ATP concentrations regulate potassium current thereby coupling energy status with membrane excitability. No specific pharmacotherapeutic options are available to treat CS but IKATP channels are pharmaceutical targets in type II diabetes or cardiac arrhythmia treatment. We have been suggested that IKATP inhibitors, glibenclamide and HMR1098, normalize CS channels. IKATP in response to Mg-ATP, glibenclamide and HMR1098 were measured by inside-out patch-clamp electrophysiology. Results were interpreted in view of cryo-EM IKATP channel structures. Mg-ATP IC50 values of outward current were increased for D207E (0.71 ± 0.14 mmol/L), S1020P (1.83 ± 0.10), S1054Y (0.95 ± 0.06) and R1154Q (0.75 ± 0.13) channels compared to H60Y (0.14 ± 0.01) and wild-type (0.15 ± 0.01). HMR1098 dose-dependently inhibited S1020P and S1054Y channels in the presence of 0.15 mmol/L Mg-ATP, reaching, at 30 μmol/L, current levels displayed by wild-type and H60Y channels in the presence of 0.15 mmol/L Mg-ATP. Glibenclamide (10 μmol/L) induced similar normalization. S1054Y sensitivity to glibenclamide increases strongly at 0.5 mmol/L Mg-ATP compared to 0.15 mmol/L, in contrast to D207E and S1020P channels. Experimental findings agree with structural considerations. We conclude that CS channel activity can be normalized by existing drugs; however, complete normalization can be achieved at supraclinical concentrations only.
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Affiliation(s)
- Marien J C Houtman
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Xingyu Chen
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - Muge Qile
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Karen Duran
- Center for Molecular Medicine, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Gijs van Haaften
- Center for Molecular Medicine, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Marcel A G van der Heyden
- Division of Heart and Lungs, Department of Medical Physiology, University Medical Center Utrecht, Utrecht, The Netherlands
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24
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Tinker A, Aziz Q, Li Y, Specterman M. ATP‐Sensitive Potassium Channels and Their Physiological and Pathophysiological Roles. Compr Physiol 2018; 8:1463-1511. [DOI: 10.1002/cphy.c170048] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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25
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Huang Y, McClenaghan C, Harter TM, Hinman K, Halabi CM, Matkovich SJ, Zhang H, Brown GS, Mecham RP, England SK, Kovacs A, Remedi MS, Nichols CG. Cardiovascular consequences of KATP overactivity in Cantu syndrome. JCI Insight 2018; 3:121153. [PMID: 30089727 DOI: 10.1172/jci.insight.121153] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/28/2018] [Indexed: 11/17/2022] Open
Abstract
Cantu syndrome (CS) is characterized by multiple vascular and cardiac abnormalities including vascular dilation and tortuosity, systemic hypotension, and cardiomegaly. The disorder is caused by gain-of-function (GOF) mutations in genes encoding pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) ATP-sensitive potassium (KATP) channel subunits. However, there is little understanding of the link between molecular dysfunction and the complex pathophysiology observed, and there is no known treatment, in large part due to the lack of appropriate preclinical disease models in which to test therapies. Notably, expression of Kir6.1 and SUR2 does not fully overlap, and the relative contribution of KATP GOF in various cardiovascular tissues remains to be elucidated. To investigate pathophysiologic mechanisms in CS we have used CRISPR/Cas9 engineering to introduce CS-associated SUR2[A478V] and Kir6.1[V65M] mutations to the equivalent endogenous loci in mice. Mirroring human CS, both of these animals exhibit low systemic blood pressure and dilated, compliant blood vessels, as well dramatic cardiac enlargement, the effects being more severe in V65M animals than in A478V animals. In both animals, whole-cell patch-clamp recordings reveal enhanced basal KATP conductance in vascular smooth muscle, explaining vasodilation and lower blood pressure, and demonstrating a cardinal role for smooth muscle KATP dysfunction in CS etiology. Echocardiography confirms in situ cardiac enlargement and increased cardiac output in both animals. Patch-clamp recordings reveal reduced ATP sensitivity of ventricular myocyte KATP channels in A478V, but normal ATP sensitivity in V65M, suggesting that cardiac remodeling occurs secondary to KATP overactivity outside of the heart. These SUR2[A478V] and Kir6.1[V65M] animals thus reiterate the key cardiovascular features seen in human CS. They establish the molecular basis of the pathophysiological consequences of reduced smooth muscle excitability resulting from SUR2/Kir6.1-dependent KATP GOF, and provide a validated animal model in which to examine potential therapeutic approaches to treating CS.
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Affiliation(s)
- Yan Huang
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Cell Biology and Physiology
| | - Conor McClenaghan
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Cell Biology and Physiology
| | - Theresa M Harter
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Cell Biology and Physiology
| | | | | | | | - Haixia Zhang
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Cell Biology and Physiology
| | - G Schuyler Brown
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Cell Biology and Physiology
| | | | - Sarah K England
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Obstetrics and Gynecology, and
| | - Attila Kovacs
- Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Maria S Remedi
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Colin G Nichols
- Center for the Investigation of Membrane Excitability Diseases, and Departments of.,Cell Biology and Physiology
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26
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Hypoxia-derived exosomes induce putative altered pathways in biosynthesis and ion regulatory channels in glioblastoma cells. Biochem Biophys Rep 2018; 14:104-113. [PMID: 29872742 PMCID: PMC5986551 DOI: 10.1016/j.bbrep.2018.03.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 02/08/2018] [Accepted: 03/29/2018] [Indexed: 12/31/2022] Open
Abstract
Hypoxia, a hallmark characteristic of glioblastoma (GBM) induces changes in the transcriptome and the proteome of tumor cells. We discovered that hypoxic stress produces significant qualitative and quantitative changes in the protein content of secreted exosomes from GBM cells. Among the proteins found to be selectively elevated in hypoxic exosomes were protein-lysine 6-oxidase (LOX), thrombospondin-1 (TSP1), vascular derived endothelial factor (VEGF) and a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1), well studied contributors to tumor progression, metastasis and angiogenesis. Our findings demonstrate that hypoxic exosomes induce differential gene expression in recipient glioma cells. Glioma cells stimulated with hypoxic exosomes showed a marked upregulation of small nucleolar RNA, C/D box 116–21 (SNORD116-21) transcript among others while significantly downregulated the potassium voltage-gated channel subfamily J member 3 (KCNJ3) message. This differential expression of certain genes is governed by the protein cargo being transferred via exosomes. Additionally, compared to normoxic exosomes, hypoxic exosomes increased various angiogenic related parameters vis-à-vis, overall tube length, branching intervals and length of isolated branches studied in tube formation assay with endothelial progenitor cells (EPCs). Thus, the intercellular communication facilitated via exosomes secreted from hypoxic GBM cells induce marked changes in the expression of genes in neighboring normoxic tumor cells and possibly in surrounding stromal cells, many of which are involved in cancer progression and treatment resistance mechanisms. In GBM, hypoxic stress induces profound changes in the protein content of secreted exosomes. Hypoxic exosomal contents induce angiogenesis and significant changes in recipient GBM cell transcriptome. Hypoxic exosomes play a major role leading to tumor proliferation, tumor growth and cell survival.
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McClenaghan C, Hanson A, Sala-Rabanal M, Roessler HI, Josifova D, Grange DK, van Haaften G, Nichols CG. Cantu syndrome-associated SUR2 (ABCC9) mutations in distinct structural domains result in K ATP channel gain-of-function by differential mechanisms. J Biol Chem 2017; 293:2041-2052. [PMID: 29275331 DOI: 10.1074/jbc.ra117.000351] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/20/2017] [Indexed: 12/25/2022] Open
Abstract
The complex disorder Cantu syndrome (CS) arises from gain-of-function mutations in either KCNJ8 or ABCC9, the genes encoding the Kir6.1 and SUR2 subunits of ATP-sensitive potassium (KATP) channels, respectively. Recent reports indicate that such mutations can increase channel activity by multiple molecular mechanisms. In this study, we determined the mechanism by which KATP function is altered by several substitutions in distinct structural domains of SUR2: D207E in the intracellular L0-linker and Y985S, G989E, M1060I, and R1154Q/R1154W in TMD2. We engineered substitutions at their equivalent positions in rat SUR2A (D207E, Y981S, G985E, M1056I, and R1150Q/R1150W) and investigated functional consequences using macroscopic rubidium (86Rb+) efflux assays and patch-clamp electrophysiology. Our results indicate that D207E increases KATP channel activity by increasing intrinsic stability of the open state, whereas the cluster of Y981S/G985E/M1056I substitutions, as well as R1150Q/R1150W, augmented Mg-nucleotide activation. We also tested the responses of these channel variants to inhibition by the sulfonylurea drug glibenclamide, a potential pharmacotherapy for CS. None of the D207E, Y981S, G985E, or M1056I substitutions had a significant effect on glibenclamide sensitivity. However, Gln and Trp substitution at Arg-1150 significantly decreased glibenclamide potency. In summary, these results provide additional confirmation that mutations in CS-associated SUR2 mutations result in KATP gain-of-function. They help link CS genotypes to phenotypes and shed light on the underlying molecular mechanisms, including consequences for inhibitory drug sensitivity, insights that may inform the development of therapeutic approaches to manage CS.
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Affiliation(s)
| | - Alex Hanson
- From the Departments of Cell Biology and Physiology and
| | | | - Helen I Roessler
- the Department of Medical Genetics, University Medical Center Utrecht, Postbus 85500, 3508 GA Utrecht, The Netherlands, and
| | - Dragana Josifova
- the Guy's and St. Thomas NHS Trust, Clinical Genetics Department, Great Maze Pond, London SE1 9RT, United Kingdom
| | - Dorothy K Grange
- Pediatrics, Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - Gijs van Haaften
- the Department of Medical Genetics, University Medical Center Utrecht, Postbus 85500, 3508 GA Utrecht, The Netherlands, and
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