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Efthymiou S, Scala M, Nagaraj V, Ochenkowska K, Komdeur FL, Liang RA, Abdel-Hamid MS, Sultan T, Barøy T, Van Ghelue M, Vona B, Maroofian R, Zafar F, Alkuraya FS, Zaki MS, Severino M, Duru KC, Tryon RC, Brauteset LV, Ansari M, Hamilton M, van Haelst MM, van Haaften G, Zara F, Houlden H, Samarut É, Nichols CG, Smeland MF, McClenaghan C. Novel loss-of-function variants expand ABCC9-related intellectual disability and myopathy syndrome. Brain 2024; 147:1822-1836. [PMID: 38217872 PMCID: PMC11068106 DOI: 10.1093/brain/awae010] [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: 06/25/2023] [Revised: 11/22/2023] [Accepted: 12/30/2023] [Indexed: 01/15/2024] Open
Abstract
Loss-of-function mutation of ABCC9, the gene encoding the SUR2 subunit of ATP sensitive-potassium (KATP) channels, was recently associated with autosomal recessive ABCC9-related intellectual disability and myopathy syndrome (AIMS). Here we identify nine additional subjects, from seven unrelated families, harbouring different homozygous loss-of-function variants in ABCC9 and presenting with a conserved range of clinical features. All variants are predicted to result in severe truncations or in-frame deletions within SUR2, leading to the generation of non-functional SUR2-dependent KATP channels. Affected individuals show psychomotor delay and intellectual disability of variable severity, microcephaly, corpus callosum and white matter abnormalities, seizures, spasticity, short stature, muscle fatigability and weakness. Heterozygous parents do not show any conserved clinical pathology but report multiple incidences of intra-uterine fetal death, which were also observed in an eighth family included in this study. In vivo studies of abcc9 loss-of-function in zebrafish revealed an exacerbated motor response to pentylenetetrazole, a pro-convulsive drug, consistent with impaired neurodevelopment associated with an increased seizure susceptibility. Our findings define an ABCC9 loss-of-function-related phenotype, expanding the genotypic and phenotypic spectrum of AIMS and reveal novel human pathologies arising from KATP channel dysfunction.
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Affiliation(s)
- Stephanie Efthymiou
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Marcello Scala
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, 16147 Genoa, Italy
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Vini Nagaraj
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Katarzyna Ochenkowska
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - Fenne L Komdeur
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Robin A Liang
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Mohamed S Abdel-Hamid
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | - Tipu Sultan
- Department of Pediatric Neurology, Children Hospital, University of Child Health Sciences, Lahore, Punjab 54000, Pakistan
| | - Tuva Barøy
- Department of Medical Genetics, Oslo University Hospital, 0450 Oslo, Norway
| | - Marijke Van Ghelue
- Department of Medical Genetics, Division of Child and Adolescent Health, University Hospital of North Norway, 9019 Tromsø, Norway
| | - Barbara Vona
- Institute of Human Genetics and Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Reza Maroofian
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Faisal Zafar
- Department of Paediatric Neurology, Children’s Hospital and Institute of Child Health, Multan, Punjab 60000, Pakistan
| | - Fowzan S Alkuraya
- Department of Translational Genomics, Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center, Riyadh 12713, Saudi Arabia
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt
| | | | - Kingsley C Duru
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
| | - Robert C Tryon
- Department of Cell Biology and Physiology, and Center for the Investigation of Membrane Excitability Diseases (CIMED), Washington University, St Louis, MO 63110, USA
| | - Lin Vigdis Brauteset
- Division of Habilitation for Children, Innlandet Hospital Sanderud, Hamar 2312, Norway
| | - Morad Ansari
- South East Scotland Genetic Service, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Mark Hamilton
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| | - Mieke M van Haelst
- Section Clinical Genetics, Department of Human Genetics and Amsterdam Reproduction and Development, Amsterdam University Medical Centers, 1105 AZ, Amsterdam, The Netherlands
| | - Gijs van Haaften
- Department of Genetics, University Medical Center, Utrecht, 3584 CX, The Netherlands
| | - Federico Zara
- U.O.C. Genetica Medica, IRCCS Istituto Giannina Gaslini, 16147 Genoa, Italy
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Éric Samarut
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), and Department of Neuroscience, Université de Montréal, Montreal H2X 0A9, Quebec, Canada
| | - 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
| | - Marie F Smeland
- Department of Pediatric Rehabilitation, University Hospital of North Norway, 9019 Tromsø, Norway
- Institute of Clinical Medicine, UiT The Arctic University of Norway, 9019, Tromsø, Norway
| | - Conor McClenaghan
- Center for Advanced Biotechnology and Medicine, and Departments of Pharmacology and Medicine, Robert Wood Johnson Medical School, Rutgers the State University of New Jersey, Piscatway, NJ 08854, USA
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Vinci M, Vitello GA, Greco D, Treccarichi S, Ragalmuto A, Musumeci A, Fallea A, Federico C, Calì F, Saccone S, Elia M. Next Generation Sequencing and Electromyography Reveal the Involvement of the P2RX6 Gene in Myopathy. Curr Issues Mol Biol 2024; 46:1150-1163. [PMID: 38392191 PMCID: PMC10887510 DOI: 10.3390/cimb46020073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/18/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024] Open
Abstract
Ion channelopathies result from impaired ion channel protein function, due to mutations affecting ion transport across cell membranes. Over 40 diseases, including neuropathy, pain, migraine, epilepsy, and ataxia, are associated with ion channelopathies, impacting electrically excitable tissues and significantly affecting skeletal muscle. Gene mutations affecting transmembrane ionic flow are strongly linked to skeletal muscle disorders, particularly myopathies, disrupting muscle excitability and contraction. Electromyography (EMG) analysis performed on a patient who complained of weakness and fatigue revealed the presence of primary muscular damage, suggesting an early-stage myopathy. Whole exome sequencing (WES) did not detect potentially causative variants in known myopathy-associated genes but revealed a novel homozygous deletion of the P2RX6 gene likely disrupting protein function. The P2RX6 gene, predominantly expressed in skeletal muscle, is an ATP-gated ion channel receptor belonging to the purinergic receptors (P2RX) family. In addition, STRING pathways suggested a correlation with more proteins having a plausible role in myopathy. No previous studies have reported the implication of this gene in myopathy. Further studies are needed on patients with a defective ion channel pathway, and the use of in vitro functional assays in suppressing P2RX6 gene expression will be required to validate its functional role.
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Affiliation(s)
| | | | | | | | | | | | | | - Concetta Federico
- Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy
| | | | - Salvatore Saccone
- Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124 Catania, Italy
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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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Takács R, Kovács P, Ebeid RA, Almássy J, Fodor J, Ducza L, Barrett-Jolley R, Lewis R, Matta C. Ca2+-Activated K+ Channels in Progenitor Cells of Musculoskeletal Tissues: A Narrative Review. Int J Mol Sci 2023; 24:ijms24076796. [PMID: 37047767 PMCID: PMC10095002 DOI: 10.3390/ijms24076796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/01/2023] [Accepted: 04/04/2023] [Indexed: 04/08/2023] Open
Abstract
Musculoskeletal disorders represent one of the main causes of disability worldwide, and their prevalence is predicted to increase in the coming decades. Stem cell therapy may be a promising option for the treatment of some of the musculoskeletal diseases. Although significant progress has been made in musculoskeletal stem cell research, osteoarthritis, the most-common musculoskeletal disorder, still lacks curative treatment. To fine-tune stem-cell-based therapy, it is necessary to focus on the underlying biological mechanisms. Ion channels and the bioelectric signals they generate control the proliferation, differentiation, and migration of musculoskeletal progenitor cells. Calcium- and voltage-activated potassium (KCa) channels are key players in cell physiology in cells of the musculoskeletal system. This review article focused on the big conductance (BK) KCa channels. The regulatory function of BK channels requires interactions with diverse sets of proteins that have different functions in tissue-resident stem cells. In this narrative review article, we discuss the main ion channels of musculoskeletal stem cells, with a focus on calcium-dependent potassium channels, especially on the large conductance BK channel. We review their expression and function in progenitor cell proliferation, differentiation, and migration and highlight gaps in current knowledge on their involvement in musculoskeletal diseases.
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Affiliation(s)
- Roland Takács
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Patrik Kovács
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Rana Abdelsattar Ebeid
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - János Almássy
- Department of Physiology, Faculty of Medicine, Semmelweis University, H-1428 Budapest, Hungary
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - László Ducza
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
| | - Richard Barrett-Jolley
- Department of Musculoskeletal Biology, Faculty of Health and Life Sciences, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L69 3GA, UK
| | - Rebecca Lewis
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Csaba Matta
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary
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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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6
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Jackson WF. Something's fishy: cardiovascular ATP-sensitive K + channels in zebrafish. J Physiol 2022; 600:169-170. [PMID: 34951483 DOI: 10.1113/jp282628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
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