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Wong SH, Liou YM, Yang JJ, Lee IC. KCNQ2 mutations cause unique neonatal behavior arrests without motor seizures: Functional characterization. Epilepsy Behav 2024; 156:109798. [PMID: 38788659 DOI: 10.1016/j.yebeh.2024.109798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/15/2024] [Accepted: 04/14/2024] [Indexed: 05/26/2024]
Abstract
OBJECTIVE KCNQ2 gene mutation usually manifests as neonatal seizures in the first week of life. Nonsense mutations cause a unique self-limited familial neonatal epilepsy (SLFNE), which is radically different from developmental epileptic encephalopathy (DEE). However, the exact underlying mechanisms remain unclear. METHODS The proband, along with their mother and grandmother, carried the c.1342C > T (p.Arg448Ter) mutation in the KCNQ2 gene. The clinical phenotypes, electroencephalography (EEG) findings, and neurodevelopmental outcomes were comprehensively surveyed. The mutant variants were transfected into HEK293 cells to investigate functional changes. RESULTS The proband exhibited behavior arrests, autonomic and non-motor neonatal seizures with changes in heart rate and respiration. EEG exhibited focal sharp waves. Seizures were remitted after three months of age. The neurodevelopmental outcomes at three years of age were unremarkable. A functional study demonstrated that the currents of p.Arg448Ter were non-functional in homomeric p.Arg448Ter compared with that of the KCNQ2 wild type. However, the current density and V1/2 exhibited significant improvement and close to that of the wild-type after transfection with heteromeric KCNQ2 + p.Arg448Ter and KCNQ2 + KCNQ3 + p.Arg448Ter respectively. Channel expression on the cell membrane was not visible after homomeric transfection, but not after heteromeric transfection. Retigabine did not affect homomeric p.Arg448Ter but improved heteromeric p. Arg448Ter + KCNQ2 and heteromeric KCNQ2 + Arg448Ter + KCNQ3. CONCLUSIONS The newborn carrying the p. Arg448Ter mutation presented frequent behavioral arrests, autonomic, and non-motor neonatal seizures. This unique pattern differs from KCNQ2 seizures, which typically manifest as motor seizures. Although p.Arg448Ter is a non-sense decay, the functional study demonstrated an almost-full compensation mechanism after transfection of heteromeric KCNQ2 and KCNQ3.
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Affiliation(s)
- Swee-Hee Wong
- Division of Pediatric Neurology, Department of Pediatrics, Chung Shan Medical University Hospital, Taichung, Taiwan; Institute of Medicine, School of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Ying-Ming Liou
- Department of Life Sciences, National Chung-Hsing University, Taichung, Taiwan; The iEGG and Animal Biotechnology Center, Rong Hsing Research Center for Translational Medicine, Natinal Chung Hsing University, Taichung 40227, Taiwan
| | - Jiann-Jou Yang
- Genetics Laboratory and Department of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan
| | - Inn-Chi Lee
- Division of Pediatric Neurology, Department of Pediatrics, Chung Shan Medical University Hospital, Taichung, Taiwan; Institute of Medicine, School of Medicine, Chung Shan Medical University, Taichung, Taiwan.
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Saez-Matia A, Ibarluzea MG, M-Alicante S, Muguruza-Montero A, Nuñez E, Ramis R, Ballesteros OR, Lasa-Goicuria D, Fons C, Gallego M, Casis O, Leonardo A, Bergara A, Villarroel A. MLe-KCNQ2: An Artificial Intelligence Model for the Prognosis of Missense KCNQ2 Gene Variants. Int J Mol Sci 2024; 25:2910. [PMID: 38474157 DOI: 10.3390/ijms25052910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 02/27/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024] Open
Abstract
Despite the increasing availability of genomic data and enhanced data analysis procedures, predicting the severity of associated diseases remains elusive in the absence of clinical descriptors. To address this challenge, we have focused on the KV7.2 voltage-gated potassium channel gene (KCNQ2), known for its link to developmental delays and various epilepsies, including self-limited benign familial neonatal epilepsy and epileptic encephalopathy. Genome-wide tools often exhibit a tendency to overestimate deleterious mutations, frequently overlooking tolerated variants, and lack the capacity to discriminate variant severity. This study introduces a novel approach by evaluating multiple machine learning (ML) protocols and descriptors. The combination of genomic information with a novel Variant Frequency Index (VFI) builds a robust foundation for constructing reliable gene-specific ML models. The ensemble model, MLe-KCNQ2, formed through logistic regression, support vector machine, random forest and gradient boosting algorithms, achieves specificity and sensitivity values surpassing 0.95 (AUC-ROC > 0.98). The ensemble MLe-KCNQ2 model also categorizes pathogenic mutations as benign or severe, with an area under the receiver operating characteristic curve (AUC-ROC) above 0.67. This study not only presents a transferable methodology for accurately classifying KCNQ2 missense variants, but also provides valuable insights for clinical counseling and aids in the determination of variant severity. The research context emphasizes the necessity of precise variant classification, especially for genes like KCNQ2, contributing to the broader understanding of gene-specific challenges in the field of genomic research. The MLe-KCNQ2 model stands as a promising tool for enhancing clinical decision making and prognosis in the realm of KCNQ2-related pathologies.
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Affiliation(s)
| | - Markel G Ibarluzea
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
| | - Sara M-Alicante
- Instituto Biofisika, CSIC-UPV/EHU, 48940 Leioa, Spain
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
| | | | - Eider Nuñez
- Instituto Biofisika, CSIC-UPV/EHU, 48940 Leioa, Spain
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
| | - Rafael Ramis
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
| | - Oscar R Ballesteros
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, 20018 Donostia, Spain
| | | | - Carmen Fons
- Pediatric Neurology Department, Sant Joan de Déu Hospital, Institut de Recerca Sant Joan de Déu, Barcelona University, 08950 Barcelona, Spain
| | - Mónica Gallego
- Departamento de Fisiología, Universidad del País Vasco, UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Oscar Casis
- Departamento de Fisiología, Universidad del País Vasco, UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Aritz Leonardo
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
| | - Aitor Bergara
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, 20018 Donostia, Spain
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3
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Zhang Y, Xue Y, Ma Y, Du X, Lu B, Wang Y, Yan Z. Improved classification and pathogenicity assessment by comprehensive functional studies in a large data set of KCNQ2 variants. Life Sci 2024; 339:122378. [PMID: 38142737 DOI: 10.1016/j.lfs.2023.122378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 12/11/2023] [Accepted: 12/19/2023] [Indexed: 12/26/2023]
Abstract
AIMS The paucity of functional annotations on hundreds of KCNQ2 variants impedes the diagnosis and treatment of KCNQ2-related disorders. The aims of this work were to determine the functional properties of 331 clinical KCNQ2 variants, interpreted the pathogenicity of 331 variants using functional data,and explored the association between homomeric channel functions and phenotypes. MAIN METHODS We collected 145 KCNQ2 variants from 232 epilepsy patients and 186 KCNQ2 missense variants from the ClinVar database. Whole-cell patch-clamp recording was used to classify the function of 331 variants. Subsequently, we proposed 24 criteria for the pathogenicity interpretation of KCNQ2 variants and used them to assess pathogenicity of 331 variants. Finally, we analyzed the clinical phenotypes of patients carrying these variants, and explored the correlations between functional mechanisms and phenotypes. KEY FINDINGS In the homozygous state, 287 were classified as loss-of-function and 14 as gain-of-function. In the more clinically relative heterozygous state, 200 variants exhibited functional impairment, 121 of which showed dominant-negative effects on wild-type KCNQ2 subunits. After introducing functional data as strong-level evidence to interpret pathogenicity, over half of variants (169/331) were reclassified and 254 were classified as pathogenic/likely pathogenic. Moreover, dominant-negative effect and haploinsufficiency were identified as primary mechanisms in DEE/ID and SeLNE, respectively. The degree of impairment of channel function correlated with the phenotype severity. SIGNIFICANCE Our study reveals the possible cause of KCNQ2-related disorders at the molecular level, provides compelling evidence for clinical classification of KCNQ2 variants, and expands the knowledge of correlations between functional mechanisms and phenotypes.
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Affiliation(s)
- Yuwei Zhang
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China; Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China.
| | - Yuqing Xue
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China; Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China.
| | - Yu Ma
- Department of Neurology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Xiaonan Du
- Department of Neurology, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Boxun Lu
- Neurology Department at Huashan Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, School of Life Sciences, Fudan University, Shanghai, China.
| | - Yi Wang
- Department of Neurology, Children's Hospital of Fudan University, Shanghai 201102, China.
| | - Zhiqiang Yan
- Human Phenome Institute, School of Life Sciences, Fudan University, Shanghai 200438, China; State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200438, China; Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen 518132, China.
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4
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Abreo TJ, Thompson EC, Madabushi A, Soh H, Varghese N, Vanoye CG, Springer K, Park KL, Johnson J, Sims S, Ji Z, Chavez AG, Jankovic MJ, Habte B, Zuberi A, Lutz C, Wang Z, Krishnan V, Dudler L, Einsele-Scholz S, Noebels JL, George AL, Maheshwari A, Tzingounis AV, Cooper EC. Plural molecular and cellular mechanisms of pore domain KCNQ2 encephalopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.04.574177. [PMID: 38260608 PMCID: PMC10802467 DOI: 10.1101/2024.01.04.574177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
KCNQ2 variants in children with neurodevelopmental impairment are difficult to assess due to their heterogeneity and unclear pathogenic mechanisms. We describe a child with neonatal-onset epilepsy, developmental impairment of intermediate severity, and KCNQ2 G256W heterozygosity. Analyzing prior KCNQ2 channel cryoelectron microscopy models revealed G256 as keystone of an arch-shaped non-covalent bond network linking S5, the pore turret, and the ion path. Co-expression with G256W dominantly suppressed conduction by wild-type subunits in heterologous cells. Ezogabine partly reversed this suppression. G256W/+ mice have epilepsy leading to premature deaths. Hippocampal CA1 pyramidal cells from G256W/+ brain slices showed hyperexcitability. G256W/+ pyramidal cell KCNQ2 and KCNQ3 immunolabeling was significantly shifted from axon initial segments to neuronal somata. Despite normal mRNA levels, G256W/+ mouse KCNQ2 protein levels were reduced by about 50%. Our findings indicate that G256W pathogenicity results from multiplicative effects, including reductions in intrinsic conduction, subcellular targeting, and protein stability. These studies reveal pore "turret arch" bonding as a KCNQ structural novelty and introduce a valid animal model of KCNQ2 encephalopathy. Our results, spanning structure to behavior, may be broadly applicable because the majority of KCNQ2 encephalopathy patients share variants near the selectivity filter.
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Affiliation(s)
- Timothy J Abreo
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Emma C Thompson
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Anuraag Madabushi
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Heun Soh
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Nissi Varghese
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Carlos G Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Kristen Springer
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Kristen L Park
- Department of Pediatrics, Childrens Colorado, University of Colorado, Aurora, CO, USA
- Department of Neurology, Childrens Colorado, University of Colorado, Aurora, CO, USA
| | | | | | - Zhigang Ji
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Ana G Chavez
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | | | - Bereket Habte
- Department of Pediatrics, Childrens Colorado, University of Colorado, Aurora, CO, USA
- Department of Neurology, Childrens Colorado, University of Colorado, Aurora, CO, USA
| | - Aamir Zuberi
- The Rare Disease Translational Center, Jackson Laboratory, Bar Harbor, ME, USA
| | - Cathleen Lutz
- The Rare Disease Translational Center, Jackson Laboratory, Bar Harbor, ME, USA
| | - Zhao Wang
- Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
- CryoEM Core, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Vaishnav Krishnan
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USA
| | - Lisa Dudler
- Center for Human Genetics Tübingen, Tübingen, Germany
| | | | - Jeffrey L Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Atul Maheshwari
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | | | - Edward C Cooper
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
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5
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Soldovieri MV, Ambrosino P, Mosca I, Servettini I, Pietrunti F, Belperio G, Syrbe S, Taglialatela M, Lemke JR. De novo variants in KCNA3 cause developmental and epileptic encephalopathy. Ann Neurol 2024; 95:365-376. [PMID: 37964487 DOI: 10.1002/ana.26826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 10/06/2023] [Accepted: 10/23/2023] [Indexed: 11/16/2023]
Abstract
OBJECTIVE Variants in several potassium channel genes, including KCNA1 and KCNA2, cause Developmental and Epileptic Encephalopathies (DEEs). We investigated whether variants in KCNA3, another mammalian homologue of the Drosophila shaker family and encoding for Kv1.3 subunits, can cause DEE. METHODS Genetic analysis of study individuals was performed by routine exome or genome sequencing, usually of parent-offspring trios. Phenotyping was performed via a standard clinical questionnaire. Currents from wild-type and/or mutant Kv1.3 subunits were investigated by whole-cell patch-clamp upon their heterologous expression. RESULTS Fourteen individuals, each carrying a de novo heterozygous missense variant in KCNA3, were identified. Most (12/14; 86%) had DEE with marked speech delay with or without motor delay, intellectual disability, epilepsy, and autism spectrum disorder. Functional analysis of Kv1.3 channels carrying each variant revealed heterogeneous functional changes, ranging from "pure" loss-of-function (LoF) effects due to faster inactivation kinetics, depolarized voltage-dependence of activation, slower activation kinetics, increased current inactivation, reduced or absent currents with or without dominant-negative effects, to "mixed" loss- and gain-of-function (GoF) effects. Compared to controls, Kv1.3 currents in lymphoblasts from 1 of the proband displayed functional changes similar to those observed upon heterologous expression of channels carrying the same variant. The antidepressant drug fluoxetine inhibited with similar potency the currents from wild-type and 1 of the Kv1.3 GoF variant. INTERPRETATION We describe a novel association of de novo missense variants in KCNA3 with a human DEE, and provide evidence that fluoxetine might represent a potential targeted treatment for individuals carrying variants with significant GoF effects. ANN NEUROL 2024;95:365-376.
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Affiliation(s)
| | - Paolo Ambrosino
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Ilaria Mosca
- Department of Medicine and Health Science "V. Tiberio", University of Molise, Campobasso, Italy
| | - Ilenio Servettini
- Department of Medicine and Health Science "V. Tiberio", University of Molise, Campobasso, Italy
| | - Francesca Pietrunti
- Department of Medicine and Health Science "V. Tiberio", University of Molise, Campobasso, Italy
| | - Giorgio Belperio
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Steffen Syrbe
- Center for Pediatrics and Adolescent Medicine, Division of Pediatric Epileptology, University Hospital Heidelberg, Heidelberg, Germany
| | - Maurizio Taglialatela
- Department of Neuroscience, Division of Pharmacology, University of Naples "Federico II", Naples, Italy
| | - Johannes R Lemke
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
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6
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Bayat A, Iavarone S, Miceli F, Jakobsen AV, Johannesen KM, Nikanorova M, Ploski R, Szymanska K, Flamini R, Cooper EC, Weckhuysen S, Taglialatela M, Møller RS. Phenotypic and functional assessment of two novel KCNQ2 gain-of-function variants Y141N and G239S and effects of amitriptyline treatment. Neurotherapeutics 2024; 21:e00296. [PMID: 38241158 PMCID: PMC10903081 DOI: 10.1016/j.neurot.2023.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 01/21/2024] Open
Abstract
While loss-of-function (LoF) variants in KCNQ2 are associated with a spectrum of neonatal-onset epilepsies, gain-of-function (GoF) variants cause a more complex phenotype that precludes neonatal-onset epilepsy. In the present work, the clinical features of three patients carrying a de novo KCNQ2 Y141N (n = 1) or G239S variant (n = 2) respectively, are described. All three patients had a mild global developmental delay, with prominent language deficits, and strong activation of interictal epileptic activity during sleep. Epileptic seizures were not reported. The absence of neonatal seizures suggested a GoF effect and prompted functional testing of the variants. In vitro whole-cell patch-clamp electrophysiological experiments in Chinese Hamster Ovary cells transiently-transfected with the cDNAs encoding Kv7.2 subunits carrying the Y141N or G239S variants in homomeric or heteromeric configurations with Kv7.2 subunits, revealed that currents from channels incorporating mutant subunits displayed increased current densities and hyperpolarizing shifts of about 10 mV in activation gating; both these functional features are consistent with an in vitro GoF phenotype. The antidepressant drug amitriptyline induced a reversible and concentration-dependent inhibition of current carried by Kv7.2 Y141N and G239S mutant channels. Based on in vitro results, amitriptyline was prescribed in one patient (G239S), prompting a significant improvement in motor, verbal, social, sensory and adaptive behavior skillsduring the two-year-treatment period. Thus, our results suggest that KCNQ2 GoF variants Y141N and G239S cause a mild DD with prominent language deficits in the absence of neonatal seizures and that treatment with the Kv7 channel blocker amitriptyline might represent a potential targeted treatment for patients with KCNQ2 GoF variants.
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Affiliation(s)
- Allan Bayat
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark; Department for Regional Health Research, University of Southern Denmark, Odense, Denmark; Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Stefano Iavarone
- Section of Pharmacology, Department of Neuroscience, University of Naples "Federico II", Naples, Italy
| | - Francesco Miceli
- Section of Pharmacology, Department of Neuroscience, University of Naples "Federico II", Naples, Italy
| | - Anne V Jakobsen
- Department of Pediatrics, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark
| | - Katrine M Johannesen
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark; Department of Genetics, University Hospital of Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Marina Nikanorova
- Department of Pediatrics, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark
| | - Rafal Ploski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Krystyna Szymanska
- Department of Pediatric Neurology, Medical University of Warsaw, Warsaw, Poland
| | | | - Edward C Cooper
- Departments of Neurology, Neuroscience, and Molecular and Human Genetics, Baylor College of Medicine, Houston TX, USA
| | - Sarah Weckhuysen
- Applied and Translational Genomics Group, VIB-Center for Molecular Neurology, VIB, University of Antwerp, Antwerp, Belgium; Neurology Department, University Hospital Antwerp, Antwerp, Belgium; Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium; μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Maurizio Taglialatela
- Section of Pharmacology, Department of Neuroscience, University of Naples "Federico II", Naples, Italy
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Filadelfia, Dianalund, Denmark; Department for Regional Health Research, University of Southern Denmark, Odense, Denmark
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7
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Soto-Perez J, Cleary CM, Sobrinho CR, Mulkey SB, Carroll JL, Tzingounis AV, Mulkey DK. Phox2b-expressing neurons contribute to breathing problems in Kcnq2 loss- and gain-of-function encephalopathy models. Nat Commun 2023; 14:8059. [PMID: 38052789 PMCID: PMC10698053 DOI: 10.1038/s41467-023-43834-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 11/21/2023] [Indexed: 12/07/2023] Open
Abstract
Loss- and gain-of-function variants in the gene encoding KCNQ2 channels are a common cause of developmental and epileptic encephalopathy, a condition characterized by seizures, developmental delays, breathing problems, and early mortality. To understand how KCNQ2 dysfunction impacts behavior in a mouse model, we focus on the control of breathing by neurons expressing the transcription factor Phox2b which includes respiratory neurons in the ventral parafacial region. We find Phox2b-expressing ventral parafacial neurons express Kcnq2 in the absence of other Kcnq isoforms, thus clarifying why disruption of Kcnq2 but not other channel isoforms results in breathing problems. We also find that Kcnq2 deletion or expression of a recurrent gain-of-function variant R201C in Phox2b-expressing neurons increases baseline breathing or decreases the central chemoreflex, respectively, in mice during the light/inactive state. These results uncover mechanisms underlying breathing abnormalities in KCNQ2 encephalopathy and highlight an unappreciated vulnerability of Phox2b-expressing ventral parafacial neurons to KCNQ2 pathogenic variants.
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Affiliation(s)
- J Soto-Perez
- Dept of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - C M Cleary
- Dept of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - C R Sobrinho
- Dept of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - S B Mulkey
- Prenatal Pediatrics Institute, Children's National Hospital, Departments of Neurology and Pediatrics, The George Washington Univ. School of Medicine and Health Sciences, Washington, DC, USA
| | - J L Carroll
- Dept. of Pediatrics, Univ. Arkansas for Medical Sciences, Little Rock, AR, USA
| | - A V Tzingounis
- Dept of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA.
| | - D K Mulkey
- Dept of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA.
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8
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Mínguez-Viñas T, Prakash V, Wang K, Lindström SH, Pozzi S, Scott SA, Spiteri E, Stevenson DA, Ashley EA, Gunnarsson C, Pantazis A. Two epilepsy-associated variants in KCNA2 (K V 1.2) at position H310 oppositely affect channel functional expression. J Physiol 2023; 601:5367-5389. [PMID: 37883018 DOI: 10.1113/jp285052] [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: 05/23/2023] [Accepted: 10/11/2023] [Indexed: 10/27/2023] Open
Abstract
Two KCNA2 variants (p.H310Y and p.H310R) were discovered in paediatric patients with epilepsy and developmental delay. KCNA2 encodes KV 1.2-channel subunits, which regulate neuronal excitability. Both gain and loss of KV 1.2 function cause epilepsy, precluding the prediction of variant effects; and while H310 is conserved throughout the KV -channel superfamily, it is largely understudied. We investigated both variants in heterologously expressed, human KV 1.2 channels by immunocytochemistry, electrophysiology and voltage-clamp fluorometry. Despite affecting the same channel, at the same position, and being associated with severe neurological disease, the two variants had diametrically opposite effects on KV 1.2 functional expression. The p.H310Y variant produced 'dual gain of function', increasing both cell-surface trafficking and activity, delaying channel closure. We found that the latter is due to the formation of a hydrogen bond that stabilizes the active state of the voltage-sensor domain. Additionally, H310Y abolished 'ball and chain' inactivation of KV 1.2 by KV β1 subunits, enhancing gain of function. In contrast, p.H310R caused 'dual loss of function', diminishing surface levels by multiple impediments to trafficking and inhibiting voltage-dependent channel opening. We discuss the implications for KV -channel biogenesis and function, an emergent hotspot for disease-associated variants, and mechanisms of epileptogenesis. KEY POINTS: KCNA2 encodes the subunits of KV 1.2 voltage-activated, K+ -selective ion channels, which regulate electrical signalling in neurons. We characterize two KCNA2 variants from patients with developmental delay and epilepsy. Both variants affect position H310, highly conserved in KV channels. The p.H310Y variant caused 'dual gain of function', increasing both KV 1.2-channel activity and the number of KV 1.2 subunits on the cell surface. H310Y abolished 'ball and chain' (N-type) inactivation of KV 1.2 by KV β1 subunits, enhancing the gain-of-function phenotype. The p.H310R variant caused 'dual loss of function', diminishing the presence of KV 1.2 subunits on the cell surface and inhibiting voltage-dependent channel opening. As H310Y stabilizes the voltage-sensor active conformation and abolishes N-type inactivation, it can serve as an investigative tool for functional and pharmacological studies.
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Affiliation(s)
- Teresa Mínguez-Viñas
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Varsha Prakash
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Kaiqian Wang
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sarah H Lindström
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Serena Pozzi
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Stuart A Scott
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
| | - Elizabeth Spiteri
- Department of Pathology, Stanford University School of Medicine, Stanford, California, USA
| | - David A Stevenson
- Division of Medical Genetics, Stanford University, Palo Alto, California, USA
| | - Euan A Ashley
- Division of Medical Genetics, Stanford University, Palo Alto, California, USA
| | - Cecilia Gunnarsson
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
- Department of Clinical Genetics, Linköping University, Linköping, Sweden
- Centre for Rare Diseases in South East Region of Sweden, Linköping University, Linköping, Sweden
| | - Antonios Pantazis
- Division of Neurobiology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
- Wallenberg Center for Molecular Medicine, Linköping University, Linköping, Sweden
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9
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Varghese N, Moscoso B, Chavez A, Springer K, Ortiz E, Soh H, Santaniello S, Maheshwari A, Tzingounis AV. KCNQ2/3 Gain-of-Function Variants and Cell Excitability: Differential Effects in CA1 versus L2/3 Pyramidal Neurons. J Neurosci 2023; 43:6479-6494. [PMID: 37607817 PMCID: PMC10513074 DOI: 10.1523/jneurosci.0980-23.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/09/2023] [Accepted: 08/15/2023] [Indexed: 08/24/2023] Open
Abstract
Gain-of-function (GOF) pathogenic variants in the potassium channels KCNQ2 and KCNQ3 lead to hyperexcitability disorders such as epilepsy and autism spectrum disorders. However, the underlying cellular mechanisms of how these variants impair forebrain function are unclear. Here, we show that the R201C variant in KCNQ2 has opposite effects on the excitability of two types of mouse pyramidal neurons of either sex, causing hyperexcitability in layer 2/3 (L2/3) pyramidal neurons and hypoexcitability in CA1 pyramidal neurons. Similarly, the homologous R231C variant in KCNQ3 leads to hyperexcitability in L2/3 pyramidal neurons and hypoexcitability in CA1 pyramidal neurons. However, the effects of KCNQ3 gain-of-function on excitability are specific to superficial CA1 pyramidal neurons. These findings reveal a new level of complexity in the function of KCNQ2 and KCNQ3 channels in the forebrain and provide a framework for understanding the effects of gain-of-function variants and potassium channels in the brain.SIGNIFICANCE STATEMENT KCNQ2/3 gain-of-function (GOF) variants lead to severe forms of neurodevelopmental disorders, but the mechanisms by which these channels affect neuronal activity are poorly understood. In this study, using a series of transgenic mice we demonstrate that the same KCNQ2/3 GOF variants can lead to either hyperexcitability or hypoexcitability in different types of pyramidal neurons [CA1 vs layer (L)2/3]. Additionally, we show that expression of the recurrent KCNQ2 GOF variant R201C in forebrain pyramidal neurons could lead to seizures and SUDEP. Our data suggest that the effects of KCNQ2/3 GOF variants depend on specific cell types and brain regions, possibly accounting for the diverse range of phenotypes observed in individuals with KCNQ2/3 GOF variants.
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Affiliation(s)
- Nissi Varghese
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Bruno Moscoso
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Ana Chavez
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Kristen Springer
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Erika Ortiz
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Heun Soh
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
| | - Sabato Santaniello
- Department of Biomedical Engineering and Connecticut Institute for the Brain and Cognitive Sciences, University of Connecticut, Storrs, Connecticut 06269
| | - Atul Maheshwari
- Department of Neurology, Baylor College of Medicine, Houston, Texas 77030
| | - Anastasios V Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269
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10
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Millevert C, Weckhuysen S. ILAE Genetic Literacy Series: Self-limited familial epilepsy syndromes with onset in neonatal age and infancy. Epileptic Disord 2023; 25:445-453. [PMID: 36939707 DOI: 10.1002/epd2.20026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/13/2022] [Accepted: 12/22/2022] [Indexed: 03/21/2023]
Abstract
The self-limited (familial) epilepsies with onset in neonates or infants, formerly called benign familial neonatal and/or infantile epilepsies, are autosomal dominant disorders characterized by neonatal- or infantile-onset focal motor seizures and the absence of neurodevelopmental complications. Seizures tend to remit during infancy or early childhood and are therefore called "self-limited". A positive family history for epilepsy usually suggests the genetic etiology, but incomplete penetrance and de novo inheritance occur. Here, we review the phenotypic spectrum and the genetic architecture of self-limited (familial) epilepsies with onset in neonates or infants. Using an illustrative case study, we describe important clues in recognition of these syndromes, diagnostic steps including genetic testing, management, and genetic counseling.
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Affiliation(s)
- Charissa Millevert
- Applied & Translational Neurogenomics Group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium
- Department of Neurology, University Hospital, Antwerp, Belgium
| | - Sarah Weckhuysen
- Applied & Translational Neurogenomics Group, VIB Center for Molecular Neurology, VIB, Antwerp, Belgium
- Department of Neurology, University Hospital, Antwerp, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
- Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium
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11
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Swenson KS, Gomez Wulschner LE, Hoelscher VM, Folts L, Korth KM, Oh WC, Bates EA. Fetal cannabidiol (CBD) exposure alters thermal pain sensitivity, problem-solving, and prefrontal cortex excitability. Mol Psychiatry 2023; 28:3397-3413. [PMID: 37433966 PMCID: PMC10618089 DOI: 10.1038/s41380-023-02130-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 05/13/2023] [Accepted: 06/13/2023] [Indexed: 07/13/2023]
Abstract
Thousands of people suffer from nausea with pregnancy each year. Nausea can be alleviated with cannabidiol (CBD), a primary component of cannabis that is widely available. However, it is unknown how fetal CBD exposure affects embryonic development and postnatal outcomes. CBD binds and activates receptors that are expressed in the fetal brain and are important for brain development, including serotonin receptors (5HT1A), voltage-gated potassium (Kv)7 receptors, and the transient potential vanilloid 1 receptor (TRPV1). Excessive activation of each of these receptors can disrupt neurodevelopment. Here, we test the hypothesis that fetal CBD exposure in mice alters offspring neurodevelopment and postnatal behavior. We administered 50 mg/kg CBD in sunflower oil or sunflower oil alone to pregnant mice from embryonic day 5 through birth. We show that fetal CBD exposure sensitizes adult male offspring to thermal pain through TRPV1. We show that fetal CBD exposure decreases problem-solving behaviors in female CBD-exposed offspring. We demonstrate that fetal CBD exposure increases the minimum current required to elicit action potentials and decreases the number of action potentials in female offspring layer 2/3 prefrontal cortex (PFC) pyramidal neurons. Fetal CBD exposure reduces the amplitude of glutamate uncaging-evoked excitatory post-synaptic currents, consistent with CBD-exposed female problem-solving behavior deficits. Combined, these data show that fetal CBD exposure disrupts neurodevelopment and postnatal behavior in a sex specific manner.
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Affiliation(s)
- Karli S Swenson
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Luis E Gomez Wulschner
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Victoria M Hoelscher
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Lillian Folts
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kamryn M Korth
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Won Chan Oh
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Emily Anne Bates
- Section of Developmental Biology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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12
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Hou B, Santaniello S, Tzingounis AV. KCNQ2 channels regulate the population activity of neonatal GABAergic neurons ex vivo. Front Neurol 2023; 14:1207539. [PMID: 37409016 PMCID: PMC10318362 DOI: 10.3389/fneur.2023.1207539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 05/18/2023] [Indexed: 07/07/2023] Open
Abstract
Over the last decade KCNQ2 channels have arisen as fundamental and indispensable regulators of neonatal brain excitability, with KCNQ2 loss-of-function pathogenic variants being increasingly identified in patients with developmental and epileptic encephalopathy. However, the mechanisms by which KCNQ2 loss-of-function variants lead to network dysfunction are not fully known. An important remaining knowledge gap is whether loss of KCNQ2 function alters GABAergic interneuron activity early in development. To address this question, we applied mesoscale calcium imaging ex vivo in postnatal day 4-7 mice lacking KCNQ2 channels in interneurons (Vgat-ires-cre;Kcnq2f/f;GCamp5). In the presence of elevated extracellular potassium concentrations, ablation of KCNQ2 channels from GABAergic cells increased the interneuron population activity in the hippocampal formation and regions of the neocortex. We found that this increased population activity depends on fast synaptic transmission, with excitatory transmission promoting the activity and GABAergic transmission curtailing it. Together, our data show that loss of function of KCNQ2 channels from interneurons increases the network excitability of the immature GABAergic circuits, revealing a new function of KCNQ2 channels in interneuron physiology in the developing brain.
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Affiliation(s)
- Bowen Hou
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Sabato Santaniello
- Department of Biomedical Engineering and CT Institute for the Brain and Cognitive Sciences, University of Connecticut, Storrs, CT, United States
| | - Anastasios V. Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
- Department of Biomedical Engineering and CT Institute for the Brain and Cognitive Sciences, University of Connecticut, Storrs, CT, United States
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13
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Falsaperla R, Marino SD, Salomone G, Madia F, Marino S, Tardino LG, Scalia B, Ruggieri M. Impressive efficacy of the ketogenic diet in a KCNQ2 encephalopathy infant: a case report and exhaustive literature review. Transl Pediatr 2023; 12:292-300. [PMID: 36891363 PMCID: PMC9986782 DOI: 10.21037/tp-22-258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 12/09/2022] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND KCNQ2 encephalopathy is characterized by neonatal-onset epilepsy and developmental impairment, due to "de novo" KCNQ2 pathogenic variants. According to literature data, sodium channel blocking agents appear to be the best treatment options for the disease. Reports describing the use of ketogenic diet (KD) in the KCNQ2 pediatric population are limited. The non-conservative amino acid substitution p.Ser122Leu in KCNQ2 is associated with a broad spectrum of inheritance modalities, clinical phenotypes and outcomes; no previous reports of the same variant treated with KD are available in literature. CASE DESCRIPTION We described a 22-month-old female with seizure onset on day 2 of life. At three months of age, she presented refractory status epilepticus (SE) that did not respond to midazolam and carbamazepine, which was added once a "de novo" p.Ser122Leu KCNQ2 variant was demonstrated. KD was the only treatment that led to cessation of seizures. The baby maintained seizures remission and achieved neurodevelopmental milestones. CONCLUSIONS To define an overt genotype-phenotype correlation for KCNQ2 pathogenic variants is a challenge; we propose the KD as a valuable treatment for refractory seizures and impaired neurodevelopment in infants harboring "de novo" mutations in the KCNQ2 gene.
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Affiliation(s)
- Raffaele Falsaperla
- Neonatology and Neonatal Intensive Care Unit, Hospital Policlinico "G. Rodolico-San Marco", University of Catania, Catania, Italy.,Unit of Pediatrics and Pediatric Emergency, Hospital Policlinico "G. Rodolico-San Marco", University of Catania, Catania, Italy
| | - Simona Domenica Marino
- Unit of Pediatrics and Pediatric Emergency, Hospital Policlinico "G. Rodolico-San Marco", University of Catania, Catania, Italy
| | | | - Francesca Madia
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Silvia Marino
- Unit of Pediatrics and Pediatric Emergency, Hospital Policlinico "G. Rodolico-San Marco", University of Catania, Catania, Italy
| | - Lucia Giovanna Tardino
- Unit of Pediatrics and Pediatric Emergency, Hospital Policlinico "G. Rodolico-San Marco", University of Catania, Catania, Italy
| | - Bruna Scalia
- Neonatology and Neonatal Intensive Care Unit, Hospital Policlinico "G. Rodolico-San Marco", University of Catania, Catania, Italy
| | - Martino Ruggieri
- Unit of Rare Diseases of the Nervous System in Childhood, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
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14
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Chokvithaya S, Caengprasath N, Buasong A, Jantasuwan S, Santawong K, Leela-adisorn N, Tongkobpetch S, Ittiwut C, Saengow VE, Kamolvisit W, Boonsimma P, Bongsebandhu-phubhakdi S, Shotelersuk V. Nine patients with KCNQ2-related neonatal seizures and functional studies of two missense variants. Sci Rep 2023; 13:3328. [PMID: 36849527 PMCID: PMC9971330 DOI: 10.1038/s41598-023-29924-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 02/13/2023] [Indexed: 03/01/2023] Open
Abstract
Mutations in KCNQ2 encoding for voltage-gated K channel subunits underlying the neuronal M-current have been associated with infantile-onset epileptic disorders. The clinical spectrum ranges from self-limited neonatal seizures to epileptic encephalopathy and delayed development. Mutations in KCNQ2 could be either gain- or loss-of-function which require different therapeutic approaches. To better understand genotype-phenotype correlation, more reports of patients and their mutations with elucidated molecular mechanism are needed. We studied 104 patients with infantile-onset pharmacoresistant epilepsy who underwent exome or genome sequencing. Nine patients with neonatal-onset seizures from unrelated families were found to harbor pathogenic or likely pathogenic variants in the KCNQ2 gene. The p.(N258K) was recently reported, and p. (G279D) has never been previously reported. Functional effect of p.(N258K) and p.(G279D) has never been previously studied. The cellular localization study demonstrated that the surface membrane expression of Kv7.2 carrying either variant was decreased. Whole-cell patch-clamp analyses revealed that both variants significantly impaired Kv7.2 M-current amplitude and density, conductance depolarizing shift in voltage dependence of activation, membrane resistance, and membrane time constant (Tau), indicating a loss-of-function in both the homotetrameric and heterotetrameric with Kv7.3 channels. In addition, both variants exerted dominant-negative effects in heterotetrameric with Kv7.3 channels. This study expands the mutational spectrum of KCNQ2- related epilepsy and their functional consequences provide insights into their pathomechanism.
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Affiliation(s)
- Suphalak Chokvithaya
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand ,grid.415584.90000 0004 0576 1386Department of Clinical Pathology and Medical Technology Laboratory, Queen Sirikit National Institute of Child Health, Ministry of Public Health, Bangkok, Thailand
| | - Natarin Caengprasath
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Aayalida Buasong
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Supavadee Jantasuwan
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Kanokwan Santawong
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Netchanok Leela-adisorn
- grid.7922.e0000 0001 0244 7875Department of Stem Cell and Cell, Therapy Research Unit, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Siraprapa Tongkobpetch
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Chupong Ittiwut
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Vitchayaporn Emarach Saengow
- grid.416297.f0000 0004 0388 8201Department of Pediatrics, Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima, Thailand
| | - Wuttichart Kamolvisit
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Ponghatai Boonsimma
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand. .,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand.
| | - Saknan Bongsebandhu-phubhakdi
- grid.7922.e0000 0001 0244 7875Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Chula Neuroscience Center, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | - Vorasuk Shotelersuk
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
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15
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Bartz FM, Beirow K, Wurm K, Baecker D, Link A, Bednarski PJ. A graphite furnace-atomic absorption spectrometry-based rubidium efflux assay for screening activators of the K v 7.2/3 channel. Arch Pharm (Weinheim) 2023; 356:e2200585. [PMID: 36748851 DOI: 10.1002/ardp.202200585] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/21/2022] [Accepted: 01/18/2023] [Indexed: 02/08/2023]
Abstract
For the characterization of Kv 7.2/3 channel activators, several analytical methods are available that vary in effort and cost. In addition to the technically elaborate patch-clamp method, which serves as a reference method, there exist several medium to high-throughput screening methods including a rubidium efflux flame-atomic absorption spectrometry (F-AAS) assay and a commercial thallium uptake fluorescence-based assay. In this study, the general suitability of a graphite furnace atomic absorption spectrometry (GF-AAS)-based rubidium efflux assay as a screening method for Kv 7.2/3 channel activators was demonstrated. With flupirtine serving as a reference compound, 16 newly synthesizedcompounds and the known Kv 7.2/3 activator retigabine were first classified as either active or inactive by using the GF-AAS-based rubidium (Rb) efflux assay. Then, the results were compared with a thallium (Tl) uptake fluorescence-based fluorometric imaging plate reader (FLIPR) potassium assay. Overall, 16 of 17 compounds were classified by the GF-AAS-based assay in agreement with their channel-activating properties determined by the more expensive Tl uptake, fluorescence-based assay. Thus, the performance of the GF-AAS-based Rb assay for primary drug screening of Kv 7.2/3-activating compounds was clearly demonstrated, as documented by the calculated Z'-factor of the GF-AAS-based method. Moreover, method development included optimization of the coating of the microtiter plates and the washing procedure, which extended the range of this assay to poorly adherent cells such as the HEK293 cells used in this study.
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Affiliation(s)
- Frieda-Marie Bartz
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Kristin Beirow
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Konrad Wurm
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Daniel Baecker
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Andreas Link
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
| | - Patrick J Bednarski
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, University of Greifswald, Greifswald, Germany
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16
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Stafstrom CE. The Voltage-Sensor S4 Rises to the Occasion in KCNQ2 Channel Activation. Epilepsy Curr 2023; 23:47-49. [PMID: 36923340 PMCID: PMC10009119 DOI: 10.1177/15357597221132972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Distinctive Mechanisms of Epilepsy-Causing Mutants Discovered by Measuring S4 Movement in KCNQ2 Channels Edmond MA, Hinojo-Perez A, Wu X, Perez Rodriguez ME, Barro-Soria R. Elife. 2022;11:e77030. doi:10.7554/eLife.77030 Neuronal KCNQ channels mediate the M-current, a key regulator of membrane excitability in the central and peripheral nervous systems. Mutations in KCNQ2 channels cause severe neurodevelopmental disorders, including epileptic encephalopathies. However, the impact that different mutations have on channel function remains poorly defined, largely because of our limited understanding of the voltage-sensing mechanisms that trigger channel gating. Here, we define the parameters of voltage sensor movements in wt-KCNQ2 and channels bearing epilepsy-associated mutations using cysteine accessibility and voltage clamp fluorometry (VCF). Cysteine modification reveals that a stretch of eight to nine amino acids in the S4 becomes exposed upon voltage sensing domain activation of KCNQ2 channels. VCF shows that the voltage dependence and the time course of S4 movement and channel opening/closing closely correlate. VCF reveals different mechanisms by which different epilepsy-associated mutations affect KCNQ2 channel voltage-dependent gating. This study provides insight into KCNQ2 channel function, which will aid in uncovering the mechanisms underlying channelopathies.
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Affiliation(s)
- Carl E Stafstrom
- Division of Pediatric Neurology, Johns Hopkins University School of Medicine
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17
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Brun L, Viemari J, Villard L. Mouse models of Kcnq2 dysfunction. Epilepsia 2022; 63:2813-2826. [PMID: 36047730 PMCID: PMC9828481 DOI: 10.1111/epi.17405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 01/12/2023]
Abstract
Variants in the Kv7.2 channel subunit encoded by the KCNQ2 gene cause epileptic disorders ranging from a benign form with self-limited epileptic seizures and normal development to severe forms with intractable epileptic seizures and encephalopathy. The biological mechanisms involved in these neurological diseases are still unclear. The disease remains intractable in patients affected by the severe form. Over the past 20 years, KCNQ2 models have been developed to elucidate pathological mechanisms and to identify new therapeutic targets. The diversity of Kcnq2 mouse models has proven invaluable to access neuronal networks and evaluate the associated cognitive deficits. This review summarizes the available models and their contribution to our current understanding of KCNQ2 epileptic disorders.
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Affiliation(s)
- Lucile Brun
- Aix Marseille Univ, Inserm, MMGMarseilleFrance
| | | | - Laurent Villard
- Aix Marseille Univ, Inserm, MMGMarseilleFrance,Service de Génétique Médicale, AP‐HM, Hôpital de La TimoneMarseilleFrance
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18
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Tracy GC, Wilton AR, Rhodes JS, Chung HJ. Heterozygous Deletion of Epilepsy Gene KCNQ2 Has Negligible Effects on Learning and Memory. Front Behav Neurosci 2022; 16:930216. [PMID: 35928789 PMCID: PMC9344800 DOI: 10.3389/fnbeh.2022.930216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 06/10/2022] [Indexed: 11/13/2022] Open
Abstract
Neuronal Kv7/Potassium Voltage-Gated Channel Subfamily Q (KCNQ) potassium channels underlie M-current that potently suppresses repetitive and burst firing of action potentials (APs). They are mostly heterotetramers of Kv7.2 and Kv7.3 subunits in the hippocampus and cortex, the brain regions important for cognition and behavior. Underscoring their critical roles in inhibiting neuronal excitability, autosomal dominantly inherited mutations in Potassium Voltage-Gated Channel Subfamily Q Member 2 (KCNQ2) and Potassium Voltage-Gated Channel Subfamily Q Member 3 (KCNQ3) genes are associated with benign familial neonatal epilepsy (BFNE) in which most seizures spontaneously remit within months without cognitive deficits. De novo mutations in KCNQ2 also cause epileptic encephalopathy (EE), which is characterized by persistent seizures that are often drug refractory, neurodevelopmental delay, and intellectual disability. Heterozygous expression of EE variants of KCNQ2 is recently shown to induce spontaneous seizures and cognitive deficit in mice, although it is unclear whether this cognitive deficit is caused directly by Kv7 disruption or by persistent seizures in the developing brain as a consequence of Kv7 disruption. In this study, we examined the role of Kv7 channels in learning and memory by behavioral phenotyping of the KCNQ2+/− mice, which lack a single copy of KCNQ2 but dos not display spontaneous seizures. We found that both KCNQ2+/− and wild-type (WT) mice showed comparable nociception in the tail-flick assay and fear-induced learning and memory during a passive inhibitory avoidance (IA) test and contextual fear conditioning (CFC). Both genotypes displayed similar object location and recognition memory. These findings together provide evidence that heterozygous loss of KCNQ2 has minimal effects on learning or memory in mice in the absence of spontaneous seizures.
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Affiliation(s)
- Gregory C. Tracy
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Angelina R. Wilton
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Justin S. Rhodes
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Psychology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- *Correspondence: Hee Jung Chung
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19
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Miceli F, Millevert C, Soldovieri MV, Mosca I, Ambrosino P, Carotenuto L, Schrader D, Lee HK, Riviello J, Hong W, Risen S, Emrick L, Amin H, Ville D, Edery P, de Bellescize J, Michaud V, Van-Gils J, Goizet C, Willemsen MH, Kleefstra T, Møller RS, Bayat A, Devinsky O, Sands T, Korenke GC, Kluger G, Mefford HC, Brilstra E, Lesca G, Milh M, Cooper EC, Taglialatela M, Weckhuysen S. KCNQ2 R144 variants cause neurodevelopmental disability with language impairment and autistic features without neonatal seizures through a gain-of-function mechanism. EBioMedicine 2022; 81:104130. [PMID: 35780567 PMCID: PMC9254340 DOI: 10.1016/j.ebiom.2022.104130] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 06/08/2022] [Accepted: 06/10/2022] [Indexed: 01/10/2023] Open
Abstract
Background Prior studies have revealed remarkable phenotypic heterogeneity in KCNQ2-related disorders, correlated with effects on biophysical features of heterologously expressed channels. Here, we assessed phenotypes and functional properties associated with KCNQ2 missense variants R144W, R144Q, and R144G. We also explored in vitro blockade of channels carrying R144Q mutant subunits by amitriptyline. Methods Patients were identified using the RIKEE database and through clinical collaborators. Phenotypes were collected by a standardized questionnaire. Functional and pharmacological properties of variant subunits were analyzed by whole-cell patch-clamp recordings. Findings Detailed clinical information on fifteen patients (14 novel and 1 previously published) was analyzed. All patients had developmental delay with prominent language impairment. R144Q patients were more severely affected than R144W patients. Infantile to childhood onset epilepsy occurred in 40%, while 67% of sleep-EEGs showed sleep-activated epileptiform activity. Ten patients (67%) showed autistic features. Activation gating of homomeric Kv7.2 R144W/Q/G channels was left-shifted, suggesting gain-of-function effects. Amitriptyline blocked channels containing Kv7.2 and Kv7.2 R144Q subunits. Interpretation Patients carrying KCNQ2 R144 gain-of-function variants have developmental delay with prominent language impairment, autistic features, often accompanied by infantile- to childhood-onset epilepsy and EEG sleep-activated epileptiform activity. The absence of neonatal seizures is a robust and important clinical differentiator between KCNQ2 gain-of-function and loss-of-function variants. The Kv7.2/7.3 channel blocker amitriptyline might represent a targeted treatment. Funding Supported by FWO, GSKE, KCNQ2-Cure, Jack Pribaz Foundation, European Joint Programme on Rare Disease 2020, the Italian Ministry for University and Research, the Italian Ministry of Health, the European Commission, the University of Antwerp, NINDS, and Chalk Family Foundation.
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20
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Soldovieri MV, Taglialatela M. The long and winding road to personalized medicine in KCNMA1-linked channelopathies revealed by novel variants associated with the Liang-Wang syndrome. Acta Physiol (Oxf) 2022; 235:e13854. [PMID: 35730691 DOI: 10.1111/apha.13854] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 06/17/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Maria Virginia Soldovieri
- Department of Medicine and Health Sciences "Vincenzo Tiberio", University of Molise, Campobasso, Italy
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21
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Ketamine exerts its sustained antidepressant effects via cell-type-specific regulation of Kcnq2. Neuron 2022; 110:2283-2298.e9. [PMID: 35649415 DOI: 10.1016/j.neuron.2022.05.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 03/01/2022] [Accepted: 05/02/2022] [Indexed: 12/20/2022]
Abstract
A single sub-anesthetic dose of ketamine produces a rapid and sustained antidepressant response, yet the molecular mechanisms responsible for this remain unclear. Here, we identified cell-type-specific transcriptional signatures associated with a sustained ketamine response in mice. Most interestingly, we identified the Kcnq2 gene as an important downstream regulator of ketamine action in glutamatergic neurons of the ventral hippocampus. We validated these findings through a series of complementary molecular, electrophysiological, cellular, pharmacological, behavioral, and functional experiments. We demonstrated that adjunctive treatment with retigabine, a KCNQ activator, augments ketamine's antidepressant-like effects in mice. Intriguingly, these effects are ketamine specific, as they do not modulate a response to classical antidepressants, such as escitalopram. These findings significantly advance our understanding of the mechanisms underlying the sustained antidepressant effects of ketamine, with important clinical implications.
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22
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Siracusano M, Marcovecchio C, Riccioni A, Dante C, Mazzone L. Autism Spectrum Disorder and a De Novo Kcnq2 Gene Mutation: A Case Report. Pediatr Rep 2022; 14:200-206. [PMID: 35645364 PMCID: PMC9149837 DOI: 10.3390/pediatric14020027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/05/2022] [Accepted: 04/20/2022] [Indexed: 11/16/2022] Open
Abstract
The KCNQ2 gene, encoding for the Kv7.2 subunits of the Kv7 voltage potassium channel, is involved in the modulation of neuronal excitability and plays a crucial role in brain morphogenesis and maturation during embryonic life. De novo heterozygous mutations in KCNQ2 genes are associated with early-onset epileptic encephalopathy and neurodevelopmental disorders including developmental delay and intellectual disability. However, little is known about the socio-communicative phenotype of children affected by the KCNQ2 mutation, and a detailed behavioral characterization focused on autistic symptoms has not yet been conducted. This case report describes the clinical behavioral phenotype of a 6-year-old boy carrying a de novo heterozygous KCNQ2 mutation, affected by early-onset seizures and autism spectrum disorder (ASD). We performed a neuropsychiatric assessment of cognitive, adaptive, socio-communicative and autistic symptoms through the administration of standardized tools. The main contribution of this case report is to provide a detailed developmental and behavioral characterization focused on ASD symptoms in a child with [c.812 G > A; p. (Gly271Asp)]mutation in the KCNQ2 gene.
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Affiliation(s)
- Martina Siracusano
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00133 Rome, Italy
- Child Neurology and Psychiatry Unit, Department of Neurosciences, Policlinico Tor Vergata Foundation Hospital, 00133 Rome, Italy; (C.M.); (A.R.); (C.D.); (L.M.)
- Correspondence: or
| | - Claudia Marcovecchio
- Child Neurology and Psychiatry Unit, Department of Neurosciences, Policlinico Tor Vergata Foundation Hospital, 00133 Rome, Italy; (C.M.); (A.R.); (C.D.); (L.M.)
| | - Assia Riccioni
- Child Neurology and Psychiatry Unit, Department of Neurosciences, Policlinico Tor Vergata Foundation Hospital, 00133 Rome, Italy; (C.M.); (A.R.); (C.D.); (L.M.)
- Systems Medicine Department, University of Rome Tor Vergata, 00133 Rome, Italy
| | - Caterina Dante
- Child Neurology and Psychiatry Unit, Department of Neurosciences, Policlinico Tor Vergata Foundation Hospital, 00133 Rome, Italy; (C.M.); (A.R.); (C.D.); (L.M.)
| | - Luigi Mazzone
- Child Neurology and Psychiatry Unit, Department of Neurosciences, Policlinico Tor Vergata Foundation Hospital, 00133 Rome, Italy; (C.M.); (A.R.); (C.D.); (L.M.)
- Systems Medicine Department, University of Rome Tor Vergata, 00133 Rome, Italy
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23
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Gain of function due to increased opening probability by two KCNQ5 pore variants causing developmental and epileptic encephalopathy. Proc Natl Acad Sci U S A 2022; 119:e2116887119. [PMID: 35377796 PMCID: PMC9169635 DOI: 10.1073/pnas.2116887119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Variants in genes encoding neuronally expressed potassium channel subunits are frequent causes of developmental and epileptic encephalopathies (DEEs). Characterization of their functional consequences is critical to confirm diagnosis, assess prognosis, and implement personalized treatments. In the present work, we describe two patients carrying variants in KCNQ5, a gene very recently and rarely found involved in DEEs, and reveal that they both cause remarkable gain-of-function consequences on channel activity. A PIP2-independent increase in open probability, without effects on membrane abundance or single-channel conductance, was responsible for the observed mutation-induced functional changes, thus revealing a pathomolecular disease mechanism for DEEs. Developmental and epileptic encephalopathies (DEEs) are neurodevelopmental diseases characterized by refractory epilepsy, distinct electroencephalographic and neuroradiological features, and various degrees of developmental delay. Mutations in KCNQ2, KCNQ3, and, more rarely, KCNQ5 genes encoding voltage-gated potassium channel subunits variably contributing to excitability control of specific neuronal populations at distinct developmental stages have been associated to DEEs. In the present work, the clinical features of two DEE patients carrying de novo KCNQ5 variants affecting the same residue in the pore region of the Kv7.5 subunit (G347S/A) are described. The in vitro functional properties of channels incorporating these variants were investigated with electrophysiological and biochemical techniques to highlight pathophysiological disease mechanisms. Currents carried by Kv7.5 G347 S/A channels displayed: 1) large (>10 times) increases in maximal current density, 2) the occurrence of a voltage-independent component, 3) slower deactivation kinetics, and 4) hyperpolarization shift in activation. All these functional features are consistent with a gain-of-function (GoF) pathogenetic mechanism. Similar functional changes were also observed when the same variants were introduced at the corresponding position in Kv7.2 subunits. Nonstationary noise analysis revealed that GoF effects observed for both Kv7.2 and Kv7.5 variants were mainly attributable to an increase in single-channel open probability, without changes in membrane abundance or single-channel conductance. The mutation-induced increase in channel opening probability was insensitive to manipulation of membrane levels of the critical Kv7 channel regulator PIP2. These results reveal a pathophysiological mechanism for KCNQ5-related DEEs, which might be exploited to implement personalized treatments.
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24
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Biba N, Becq H, Pallesi-Pocachard E, Sarno S, Granjeaud S, Montheil A, Kurz M, Villard L, Milh M, Santini PPL, Aniksztejn L. Time-limited alterations in cortical activity of a knock-in mice model of KCNQ2-related developmental and epileptic encephalopathy. J Physiol 2022; 600:2429-2460. [PMID: 35389519 DOI: 10.1113/jp282536] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 03/10/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The electrophysiological impact of the pathogenic c.821C>T mutation of the KCNQ2 gene (p.T274M variant in Kv7.2 subunit) related to Developmental and Epileptic Encephalopathy has been analyzed both in vivo and ex-vivo in layers II/III and V of motor cortical slice from a knock-in mice model during development at neonatal, post-weaning and juvenile stages. M current density and conductance are decreased and excitability of layers II/III pyramidal cells is increased in slices from neonatal and post-weaning KI mice but not from juvenile KI mice. M current and excitability of layer V pyramidal cells are impacted in KI mice only at post-weaning stage. Spontaneous GABAergic network-driven events are recorded until post-weaning stage and their frequency are increased in layers II/III of the KI mice. KI mice displayed spontaneous seizures preferentially at post-weaning rather than at juvenile stages. ABSTRACT De novo missense variants in the KCNQ2 gene encoding the Kv7.2 subunit of the voltage-gated potassium Kv7/M channels are the main cause of Developmental and Epileptic Encephalopathy (DEE) with neonatal onset. While seizures usually resolve during development, cognitive/motor deficits persist. To better understand the cellular mechanisms underlying network dysfunction and their progression over time, we investigated in vivo, using local field potential recordings of freely moving animals, and ex-vivo in layers II/III and V of motor cortical slices, using patch-clamp recordings, the electrophysiological properties of pyramidal cells from a heterozygous knock-in (KI) mouse model carrying the Kv7.2 p.T274M pathogenic variant during neonatal, post-weaning and juvenile developmental stages. We found that KI mice displayed spontaneous seizures preferentially at post-weaning rather than at juvenile stages. At the cellular level, the variant led to a reduction in M current density/conductance and to neuronal hyperexcitability. These alterations were observed during the neonatal period in pyramidal cells of layers II /III and during post-weaning stage in pyramidal cells of layer V. Moreover, there was an increase in the frequency of spontaneous network driven events mediated by GABA receptors suggesting that the excitability of interneurons was also increased. However, all these alterations were no more observed in layers II/III and V of juvenile mice. Thus, our data indicate that the action of the variant is developmentally regulated. This raises the possibility that the age related seizure remission observed in KCNQ2-related DEE patient results from a time limited alteration of Kv7 channels activity and neuronal excitability. Abstract figure legend Knock-in mice harboring the heterozygous pathogenic p.T274M variant in the Kv7.2 subunit (c.821C>T mutation of the KCNQ2 gene) related to Developmental and Epileptic Encephalopathy displayed epileptic seizures preferentially at post-weaning rather than at juvenile developmental stages. At cellular level, in motor cortical slices the variant led to a reduction in M current density, to a hyperexcitability of pyramidal cells and to an increase in the frequency of spontaneous network driven events mediated by GABA receptors. All these alterations are time limited and are observed in pyramidal cells of neonatal mice until post-weaning but not of juvenile mice in which the pyramidal cells have electrophysiological properties similar to those of wild-type mice. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Najoua Biba
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Hélène Becq
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Emilie Pallesi-Pocachard
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Stefania Sarno
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Samuel Granjeaud
- Centre de Recherche en Cancérologie de Marseille, INSERM, U1068, Institut Paoli Calmettes, CNRS, UMR7258, Aix-Marseille University UM 105, Marseille, France
| | - Aurélie Montheil
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Marie Kurz
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Laurent Villard
- Aix-Marseille University, INSERM, MMG, Marseille, France.,Department of Medical Genetics, La Timone Childrens's Hospital, Marseille, France
| | - Mathieu Milh
- Aix-Marseille University, INSERM, MMG, Marseille, France.,Department of Pediatric Neurology, La Timone Children's Hospital, Marseille, France
| | | | - Laurent Aniksztejn
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
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25
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Abstract
KCNQ2 and KCNQ3 channels are associated with multiple neurodevelopmental disorders and are also therapeutic targets for neurological and neuropsychiatric diseases. For more than two decades, it has been thought that most KCNQ channels in the brain are either KCNQ2/3 or KCNQ3/5 heteromers. Here, we investigated the potential heteromeric compositions of KCNQ2-containing channels. We applied split-intein protein trans-splicing to form KCNQ2/5 tandems and coexpressed these with and without KCNQ3. Unexpectedly, we found that KCNQ2/5 tandems form functional channels independent of KCNQ3 in heterologous cells. Using mass spectrometry, we went on to demonstrate that KCNQ2 associates with KCNQ5 in native channels in the brain, even in the absence of KCNQ3. Additionally, our functional heterologous expression data are consistent with the formation of KCNQ2/3/5 heteromers. Thus, the composition of KCNQ channels is more diverse than has been previously recognized, necessitating a re-examination of the genotype/phenotype relationship of KCNQ2 pathogenic variants.
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26
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Bottom-Tanzer S, Dulla C. Keeping up with KCNQ2: A New Model of Epileptic Encephalopathy. Epilepsy Curr 2022; 22:141-143. [PMID: 35444503 PMCID: PMC8988726 DOI: 10.1177/15357597221082485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
| | - Chris Dulla
- Tufts University School of Medicine, Boston, MA, USA
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27
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Vanoye CG, Desai RR, Ji Z, Adusumilli S, Jairam N, Ghabra N, Joshi N, Fitch E, Helbig KL, McKnight D, Lindy AS, Zou F, Helbig I, Cooper EC, George AL. High-throughput evaluation of epilepsy-associated KCNQ2 variants reveals functional and pharmacological heterogeneity. JCI Insight 2022; 7:156314. [PMID: 35104249 PMCID: PMC8983144 DOI: 10.1172/jci.insight.156314] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hundreds of genetic variants in KCNQ2 encoding the voltage-gated potassium channel KV7.2 are associated with early onset epilepsy and/or developmental disability, but the functional consequences of most variants are unknown. Absent functional annotation for KCNQ2 variants hinders identification of individuals who may benefit from emerging precision therapies. We employed automated patch clamp recordings to assess at, to our knowledge, an unprecedented scale the functional and pharmacological properties of 79 missense and 2 inframe deletion KCNQ2 variants. Among the variants we studied were 18 known pathogenic variants, 24 mostly rare population variants, and 39 disease-associated variants with unclear functional effects. We analyzed electrophysiological data recorded from 9,480 cells. The functional properties of 18 known pathogenic variants largely matched previously published results and validated automated patch clamp for this purpose. Unlike rare population variants, most disease-associated KCNQ2 variants exhibited prominent loss-of-function with dominant-negative effects, providing strong evidence in support of pathogenicity. All variants responded to retigabine, although there were substantial differences in maximal responses. Our study demonstrated that dominant-negative loss-of-function is a common mechanism associated with missense KCNQ2 variants. Importantly, we observed genotype-dependent differences in the response of KCNQ2 variants to retigabine, a proposed precision therapy for KCNQ2 developmental and epileptic encephalopathy.
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Affiliation(s)
- Carlos G. Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Reshma R. Desai
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Zhigang Ji
- Departments of Neurology, Neuroscience, Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Sneha Adusumilli
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nirvani Jairam
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nora Ghabra
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nishtha Joshi
- Departments of Neurology, Neuroscience, Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Eryn Fitch
- The Epilepsy NeuroGenetics Initiative (ENGIN), and,Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Katherine L. Helbig
- The Epilepsy NeuroGenetics Initiative (ENGIN), and,Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | | | | | | | - Ingo Helbig
- The Epilepsy NeuroGenetics Initiative (ENGIN), and,Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Edward C. Cooper
- Departments of Neurology, Neuroscience, Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Alfred L. George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.,Center for Pharmacogenomics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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28
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Zheng Y, Liu H, Chen Y, Dong S, Wang F, Wang S, Li GL, Shu Y, Xu F. Structural insights into the lipid and ligand regulation of a human neuronal KCNQ channel. Neuron 2021; 110:237-247.e4. [PMID: 34767770 DOI: 10.1016/j.neuron.2021.10.029] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 09/20/2021] [Accepted: 10/19/2021] [Indexed: 01/10/2023]
Abstract
The KCNQ family (KCNQ1-KCNQ5) of voltage-gated potassium channels plays critical roles in many physiological and pathological processes. It is known that the channel opening of all KCNQs relies on the signaling lipid molecule phosphatidylinositol 4,5-bisphosphate (PIP2). However, the molecular mechanism of PIP2 in modulating the opening of the four neuronal KCNQ channels (KCNQ2-KCNQ5), which are essential for regulating neuronal excitability, remains largely elusive. Here, we report the cryoelectron microscopy (cryo-EM) structures of human KCNQ4 determined in complex with the activator ML213 in the absence or presence of PIP2. Two PIP2 molecules are identified in the open-state structure of KCNQ4, which act as a bridge to couple the voltage-sensing domain (VSD) and pore domain (PD) of KCNQ4 leading to the channel opening. Our findings reveal the binding sites and activation mechanisms of ML213 and PIP2 for neuronal KCNQ channels, providing a framework for therapeutic intervention targeting on these important channels.
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Affiliation(s)
- You Zheng
- iHuman Institute, ShanghaiTech University, Shanghai, China; School of Life Science and Technology, ShanghaiTech University, Shanghai, China; Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Heng Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China; Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yuxin Chen
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Shaowei Dong
- iHuman Institute, ShanghaiTech University, Shanghai, China; School of Life Science and Technology, ShanghaiTech University, Shanghai, China; Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Fang Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Shengyi Wang
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Geng-Lin Li
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China
| | - Yilai Shu
- ENT Institute and Department of Otorhinolaryngology, Eye & ENT Hospital, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, 200031, China; Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China; NHC Key Laboratory of Hearing Medicine (Fudan University), Shanghai, 200031, China.
| | - Fei Xu
- iHuman Institute, ShanghaiTech University, Shanghai, China; School of Life Science and Technology, ShanghaiTech University, Shanghai, China; Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China.
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29
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Aiba I, Noebels JL. Kcnq2/Kv7.2 controls the threshold and bi-hemispheric symmetry of cortical spreading depolarization. Brain 2021; 144:2863-2878. [PMID: 33768249 PMCID: PMC8536937 DOI: 10.1093/brain/awab141] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 02/22/2021] [Accepted: 03/20/2021] [Indexed: 12/03/2022] Open
Abstract
Spreading depolarization is a slowly propagating wave of massive cellular depolarization associated with acute brain injury and migraine aura. Genetic studies link depolarizing molecular defects in Ca2+ flux, Na+ current in interneurons, and glial Na+-K+ ATPase with spreading depolarization susceptibility, emphasizing the important roles of synaptic activity and extracellular ionic homeostasis in determining spreading depolarization threshold. In contrast, although gene mutations in voltage-gated potassium ion channels that shape intrinsic membrane excitability are frequently associated with epilepsy susceptibility, it is not known whether epileptogenic mutations that regulate membrane repolarization also modify spreading depolarization threshold and propagation. Here we report that the Kcnq2/Kv7.2 potassium channel subunit, frequently mutated in developmental epilepsy, is a spreading depolarization modulatory gene with significant control over the seizure-spreading depolarization transition threshold, bi-hemispheric cortical expression, and diurnal temporal susceptibility. Chronic DC-band cortical EEG recording from behaving conditional Kcnq2 deletion mice (Emx1cre/+::Kcnq2flox/flox) revealed spontaneous cortical seizures and spreading depolarization. In contrast to the related potassium channel deficient model, Kv1.1-KO mice, spontaneous cortical spreading depolarizations in Kcnq2 cKO mice are tightly coupled to the terminal phase of seizures, arise bilaterally, and are observed predominantly during the dark phase. Administration of the non-selective Kv7.2 inhibitor XE991 to Kv1.1-KO mice partly reproduced the Kcnq2 cKO-like spreading depolarization phenotype (tight seizure coupling and bilateral symmetry) in these mice, indicating that Kv7.2 currents can directly and actively modulate spreading depolarization properties. In vitro brain slice studies confirmed that Kcnq2/Kv7.2 depletion or pharmacological inhibition intrinsically lowers the cortical spreading depolarization threshold, whereas pharmacological Kv7.2 activators elevate the threshold to multiple depolarizing and hypometabolic spreading depolarization triggers. Together these results identify Kcnq2/Kv7.2 as a distinctive spreading depolarization regulatory gene, and point to spreading depolarization as a potentially significant pathophysiological component of KCNQ2-linked epileptic encephalopathy syndromes. Our results also implicate KCNQ2/Kv7.2 channel activation as a potential adjunctive therapeutic target to inhibit spreading depolarization incidence.
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Affiliation(s)
- Isamu Aiba
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jeffrey L Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
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Springer K, Varghese N, Tzingounis AV. Flexible Stoichiometry: Implications for KCNQ2- and KCNQ3-Associated Neurodevelopmental Disorders. Dev Neurosci 2021; 43:191-200. [PMID: 33794528 PMCID: PMC8440324 DOI: 10.1159/000515495] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/25/2021] [Indexed: 11/19/2022] Open
Abstract
KCNQ2 and KCNQ3 pathogenic channel variants have been associated with a spectrum of developmentally regulated diseases that vary in age of onset, severity, and whether it is transient (i.e., benign familial neonatal seizures) or long-lasting (i.e., developmental and epileptic encephalopathy). KCNQ2 and KCNQ3 channels have also emerged as a target for novel antiepileptic drugs as their activation could reduce epileptic activity. Consequently, a great effort has taken place over the last 2 decades to understand the mechanisms that control the assembly, gating, and modulation of KCNQ2 and KCNQ3 channels. The current view that KCNQ2 and KCNQ3 channels assemble as heteromeric channels (KCNQ2/3) forms the basis of our understanding of KCNQ2 and KCNQ3 channelopathies and drug design. Here, we review the evidence that supports the formation of KCNQ2/3 heteromers in neurons. We also highlight functional and transcriptomic studies that suggest channel composition might not be necessarily fixed in the nervous system, but rather is dynamic and flexible, allowing some neurons to express KCNQ2 and KCNQ3 homomers. We propose that to fully understand KCNQ2 and KCNQ3 channelopathies, we need to adopt a more flexible view of KCNQ2 and KCNQ3 channel stoichiometry, which might differ across development, brain regions, cell types, and disease states.
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Affiliation(s)
- Kristen Springer
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Nissi Varghese
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Anastasios V Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
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