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Dinsdale RL, Meredith AL. Evaluation of four KCNMA1 channelopathy variants on BK channel current under Ca V1.2 activation. Channels (Austin) 2024; 18:2396346. [PMID: 39217512 DOI: 10.1080/19336950.2024.2396346] [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: 06/24/2024] [Revised: 08/14/2024] [Accepted: 08/20/2024] [Indexed: 09/04/2024] Open
Abstract
Variants in KCNMA1, encoding the voltage- and calcium-activated K+ (BK) channel, are associated with human neurological disease. The effects of gain-of-function (GOF) and loss-of-function (LOF) variants have been predominantly studied on BK channel currents evoked under steady-state voltage and Ca2+ conditions. However, in their physiological context, BK channels exist in partnership with voltage-gated Ca2+ channels and respond to dynamic changes in intracellular Ca2+ (Ca2+i). In this study, an L-type voltage-gated Ca2+ channel present in the brain, CaV1.2, was co-expressed with wild type and mutant BK channels containing GOF (D434G, N999S) and LOF (H444Q, D965V) patient-associated variants in HEK-293T cells. Whole-cell BK currents were recorded under CaV1.2 activation using buffering conditions that restrict Ca2+i to nano- or micro-domains. Both conditions permitted wild type BK current activation in response to CaV1.2 Ca2+ influx, but differences in behavior between wild type and mutant BK channels were reduced compared to prior studies in clamped Ca2+i. Only the N999S mutation produced an increase in BK current in both micro- and nano-domains using square voltage commands and was also detectable in BK current evoked by a neuronal action potential within a microdomain. These data corroborate the GOF effect of N999S on BK channel activity under dynamic voltage and Ca2+ stimuli, consistent with its pathogenicity in neurological disease. However, the patient-associated mutations D434G, H444Q, and D965V did not exhibit significant effects on BK current under CaV1.2-mediated Ca2+ influx, in contrast with prior steady-state protocols. These results demonstrate a differential potential for KCNMA1 variant pathogenicity compared under diverse voltage and Ca2+ conditions.
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Affiliation(s)
- Ria L Dinsdale
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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2
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Moldenhauer HJ, Tammen K, Meredith AL. Structural mapping of patient-associated KCNMA1 gene variants. Biophys J 2024; 123:1984-2000. [PMID: 38042986 PMCID: PMC11309989 DOI: 10.1016/j.bpj.2023.11.3404] [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: 09/08/2023] [Revised: 11/30/2023] [Accepted: 11/30/2023] [Indexed: 12/04/2023] Open
Abstract
KCNMA1-linked channelopathy is a neurological disorder characterized by seizures, motor abnormalities, and neurodevelopmental disabilities. The disease mechanisms are predicted to result from alterations in KCNMA1-encoded BK K+ channel activity; however, only a subset of the patient-associated variants have been functionally studied. The localization of these variants within the tertiary structure or evaluation by pathogenicity algorithms has not been systematically assessed. In this study, 82 nonsynonymous patient-associated KCNMA1 variants were mapped within the BK channel protein. Fifty-three variants localized within cryoelectron microscopy-resolved structures, including 21 classified as either gain of function (GOF) or loss of function (LOF) in BK channel activity. Clusters of LOF variants were identified in the pore, the AC region (RCK1), and near the Ca2+ bowl (RCK2), overlapping with sites of pharmacological or endogenous modulation. However, no clustering was found for GOF variants. To further understand variants of uncertain significance (VUSs), assessments by multiple standard pathogenicity algorithms were compared, and new thresholds for sensitivity and specificity were established from confirmed GOF and LOF variants. An ensemble algorithm was constructed (KCNMA1 meta score (KMS)), consisting of a weighted summation of this trained dataset combined with a structural component derived from the Ca2+-bound and unbound BK channels. KMS assessment differed from the highest-performing individual algorithm (REVEL) at 10 VUS residues, and a subset were studied further by electrophysiology in HEK293 cells. M578T, E656A, and D965V (KMS+;REVEL-) were confirmed to alter BK channel properties in voltage-clamp recordings, and D800Y (KMS-;REVEL+) was assessed as benign under the test conditions. However, KMS failed to accurately assess K457E. These combined results reveal the distribution of potentially disease-causing KCNMA1 variants within BK channel functional domains and pathogenicity evaluation for VUSs, suggesting strategies for improving channel-level predictions in future studies by building on ensemble algorithms such as KMS.
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Affiliation(s)
- Hans J Moldenhauer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Kelly Tammen
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland.
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Echeverría F, Gonzalez-Sanabria N, Alvarado-Sanchez R, Fernández M, Castillo K, Latorre R. Large conductance voltage-and calcium-activated K + (BK) channel in health and disease. Front Pharmacol 2024; 15:1373507. [PMID: 38584598 PMCID: PMC10995336 DOI: 10.3389/fphar.2024.1373507] [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: 01/19/2024] [Accepted: 03/12/2024] [Indexed: 04/09/2024] Open
Abstract
Large Conductance Voltage- and Calcium-activated K+ (BK) channels are transmembrane pore-forming proteins that regulate cell excitability and are also expressed in non-excitable cells. They play a role in regulating vascular tone, neuronal excitability, neurotransmitter release, and muscle contraction. Dysfunction of the BK channel can lead to arterial hypertension, hearing disorders, epilepsy, and ataxia. Here, we provide an overview of BK channel functioning and the implications of its abnormal functioning in various diseases. Understanding the function of BK channels is crucial for comprehending the mechanisms involved in regulating vital physiological processes, both in normal and pathological conditions, controlled by BK. This understanding may lead to the development of therapeutic interventions to address BK channelopathies.
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Affiliation(s)
- Felipe Echeverría
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Naileth Gonzalez-Sanabria
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Rosangelina Alvarado-Sanchez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Miguel Fernández
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Karen Castillo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
- Centro de Investigación de Estudios Avanzados del Maule, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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Çapan ÖY, Yapıcı Z, Özbil M, Çağlayan HS. Exome data of developmental and epileptic encephalopathy patients reveals de novo and inherited pathologic variants in epilepsy-associated genes. Seizure 2024; 116:51-64. [PMID: 37353388 DOI: 10.1016/j.seizure.2023.06.009] [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: 02/24/2023] [Revised: 06/04/2023] [Accepted: 06/10/2023] [Indexed: 06/25/2023] Open
Abstract
PURPOSE In Developmental and Epileptic Encephalopathies (DEEs), identifying the precise genetic factors guides the clinicians to apply the most appropriate treatment for the patient. Due to high locus heterogeneity, WES analysis is a promising approach for the genetic diagnosis of DEE. Therefore, the aim of the present study is to evaluate the utility of WES in the diagnosis and treatment of DEE patients. METHODS The exome data of 29 DEE patients were filtrated for destructive and missense mutations in 1896 epilepsy-related genes to detect the causative variants and examine the genotype-phenotype correlations. We performed Sanger sequencing with the available DNA samples to follow the co-segregation of the variants with the disease phenotype in the families. Also, the structural effects of p.Asn1053Ser, p.Pro120Ser and p.Glu1868Gly mutations on KCNMA1, NPC2, and SCN2A proteins, respectively, were evaluated by molecular dynamics (MD) and molecular docking simulations. RESULTS Out of 29, nine patients (31%) harbor pathological (P) or likely pathological (LP) mutations in SCN2A, KCNQ2, ATP1A2, KCNMA1, and MECP2 genes, and three patients have VUS variants (10%) in SCN1A and SCN2A genes. Sanger sequencing results indicated that three of the patients have de novo mutations while eight of them carry paternally and/or maternally inherited causative variants. MD and molecular docking simulations supported the destructive effects of the mutations on KCNMA1, NPC2, and SCN2A protein structures. CONCLUSION Herein we demonstrated the effectiveness of WES for DEE with high locus heterogeneity. Identification of the genetic etiology guided the clinicians to adjust the proper treatment for the patients.
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Affiliation(s)
- Özlem Yalçın Çapan
- Department of Medical Biology, Faculty of Medicine, Tekirdağ Namık Kemal University, Tekirdağ, Turkey; Department of Molecular Biology and Genetics, İstanbul Arel University, İstanbul, Turkey.
| | - Zuhal Yapıcı
- Division of Child Neurology, Department of Neurology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Mehmet Özbil
- Institute of Biotechnology, Gebze Technical University, Kocaeli, Turkiye
| | - Hande S Çağlayan
- Department of Molecular Biology and Genetics, Boğaziçi University, İstanbul, Turkey (formerly)
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Meredith AL. BK Channelopathies and KCNMA1-Linked Disease Models. Annu Rev Physiol 2024; 86:277-300. [PMID: 37906945 DOI: 10.1146/annurev-physiol-030323-042845] [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] [Indexed: 11/02/2023]
Abstract
Novel KCNMA1 variants, encoding the BK K+ channel, are associated with a debilitating dyskinesia and epilepsy syndrome. Neurodevelopmental delay, cognitive disability, and brain and structural malformations are also diagnosed at lower incidence. More than half of affected individuals present with a rare negative episodic motor disorder, paroxysmal nonkinesigenic dyskinesia (PNKD3). The mechanistic relationship of PNKD3 to epilepsy and the broader spectrum of KCNMA1-associated symptomology is unknown. This review summarizes patient-associated KCNMA1 variants within the BK channel structure, functional classifications, genotype-phenotype associations, disease models, and treatment. Patient and transgenic animal data suggest delineation of gain-of-function (GOF) and loss-of-function KCNMA1 neurogenetic disease, validating two heterozygous alleles encoding GOF BK channels (D434G and N999S) as causing seizure and PNKD3. This discovery led to a variant-defined therapeutic approach for PNKD3, providing initial insight into the neurological basis. A comprehensive clinical definition of monogenic KCNMA1-linked disease and the neuronal mechanisms currently remain priorities for continued investigation.
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Affiliation(s)
- Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, USA;
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Zhao X, He Z, Li Y, Yang X, Li B. Atypical absence seizures and gene variants: A gene-based review of etiology, electro-clinical features, and associated epilepsy syndrome. Epilepsy Behav 2024; 151:109636. [PMID: 38232560 DOI: 10.1016/j.yebeh.2024.109636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/01/2024] [Accepted: 01/05/2024] [Indexed: 01/19/2024]
Abstract
Atypical absence seizures are generalized non-convulsive seizures that often occur in children with cognitive impairment. They are common in refractory epilepsy and have been recognized as one of the hallmarks of developmental epileptic encephalopathies. Notably, pathogenic variants associated with AAS, such as GABRG2, GABRG3, SLC6A1, CACNB4, SCN8A, and SYNGAP1, are also linked to developmental epileptic encephalopathies. Atypical absences differ from typical absences in that they are frequently drug-resistant and the prognosis is dependent on the etiology or related epileptic syndromes. To improve clinicians' understanding of atypical absences and provide novel perspectives for clinical treatment, we have reviewed the electro-clinical characteristics, etiologies, treatment, and prognosis of atypical absences, with a focus on the etiology of advancements in gene variants, shedding light on potential avenues for improved clinical management.
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Affiliation(s)
| | - Zimeng He
- Shandong University, Jinan, Shandong, China
| | - Yumei Li
- Shandong University, Jinan, Shandong, China
| | - Xiaofan Yang
- Shandong University, Jinan, Shandong, China; Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, Shandong, China.
| | - Baomin Li
- Shandong University, Jinan, Shandong, China; Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, Shandong, China.
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Kalyakulina A, Yusipov I, Kondakova E, Bacalini MG, Giuliani C, Sivtseva T, Semenov S, Ksenofontov A, Nikolaeva M, Khusnutdinova E, Zakharova R, Vedunova M, Franceschi C, Ivanchenko M. Epigenetics of the far northern Yakutian population. Clin Epigenetics 2023; 15:189. [PMID: 38053163 PMCID: PMC10699032 DOI: 10.1186/s13148-023-01600-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] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 11/13/2023] [Indexed: 12/07/2023] Open
Abstract
BACKGROUND Yakuts are one of the indigenous populations of the subarctic and arctic territories of Siberia characterized by a continental subarctic climate with severe winters, with the regular January average temperature in the regional capital city of Yakutsk dipping below - 40 °C. The epigenetic mechanisms of adaptation to such ecologies and environments and, in particular, epigenetic age acceleration in the local population have not been studied before. RESULTS This work reports the first epigenetic study of the Yakutian population using whole-blood DNA methylation data, supplemented with the comparison to the residents of Central Russia. Gene set enrichment analysis revealed, among others, geographic region-specific differentially methylated regions associated with adaptation to climatic conditions (water consumption, digestive system regulation), aging processes (actin filament activity, cell fate), and both of them (channel activity, regulation of steroid and corticosteroid hormone secretion). Further, it is demonstrated that the epigenetic age acceleration of the Yakutian representatives is significantly higher than that of Central Russia counterparts. For both geographic regions, we showed that epigenetically males age faster than females, whereas no significant sex differences were found between the regions. CONCLUSIONS We performed the first study of the epigenetic data of the Yakutia cohort, paying special attention to region-specific features, aging processes, age acceleration, and sex specificity.
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Affiliation(s)
- Alena Kalyakulina
- Institute of Information Technologies, Mathematics and Mechanics, Lobachevsky State University, Nizhny Novgorod, 603022, Russia.
- Institute of Biogerontology, Lobachevsky State University, Nizhny Novgorod, 603022, Russia.
| | - Igor Yusipov
- Institute of Information Technologies, Mathematics and Mechanics, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
- Institute of Biogerontology, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
| | - Elena Kondakova
- Institute of Biogerontology, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
- Institute of Biology and Biomedicine, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
| | | | - Cristina Giuliani
- Laboratory of Molecular Anthropology and Centre for Genome Biology, Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126, Bologna, Italy
| | - Tatiana Sivtseva
- Research Center of the Medical Institute of the North-Eastern Federal University M.K. Ammosova, Yakutsk, 677013, Russia
| | - Sergey Semenov
- Research Center of the Medical Institute of the North-Eastern Federal University M.K. Ammosova, Yakutsk, 677013, Russia
| | - Artem Ksenofontov
- State Budgetary Institution of the Republic of Sakha (Yakutia) Republican Center for Public Health and Medical Prevention, Yakutsk, 677001, Russia
| | - Maria Nikolaeva
- Research Center of the Medical Institute of the North-Eastern Federal University M.K. Ammosova, Yakutsk, 677013, Russia
| | - Elza Khusnutdinova
- Institute of Biochemistry and Genetics, Ufa Federal Research Centre of the Russian Academy of Sciences, Ufa, Russia, 450054
| | - Raisa Zakharova
- Research Center of the Medical Institute of the North-Eastern Federal University M.K. Ammosova, Yakutsk, 677013, Russia
| | - Maria Vedunova
- Institute of Biology and Biomedicine, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
| | - Claudio Franceschi
- Institute of Information Technologies, Mathematics and Mechanics, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
- Institute of Biogerontology, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
| | - Mikhail Ivanchenko
- Institute of Information Technologies, Mathematics and Mechanics, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
- Institute of Biogerontology, Lobachevsky State University, Nizhny Novgorod, 603022, Russia
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Moldenhauer HJ, Tammen K, Meredith AL. Structural mapping of patient-associated KCNMA1 gene variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.27.550850. [PMID: 37546746 PMCID: PMC10402178 DOI: 10.1101/2023.07.27.550850] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
KCNMA1-linked channelopathy is a neurological disorder characterized by seizures, motor abnormalities, and neurodevelopmental disabilities. The disease mechanisms are predicted to result from alterations in KCNMA1-encoded BK K+ channel activity; however, only a subset of the patient-associated variants have been functionally studied. The localization of these variants within the tertiary structure or evaluation by pathogenicity algorithms has not been systematically assessed. In this study, 82 nonsynonymous patient-associated KCNMA1 variants were mapped within the BK channel protein. Fifty-three variants localized within cryo-EM resolved structures, including 21 classified as either gain-of-function (GOF) or loss-of-function (LOF) in BK channel activity. Clusters of LOF variants were identified in the pore, the AC region (RCK1), and near the Ca 2+ bowl (RCK2), overlapping with sites of pharmacological or endogenous modulation. However, no clustering was found for GOF variants. To further understand variants of uncertain significance (VUS), assessments by multiple standard pathogenicity algorithms were compared, and new thresholds for sensitivity and specificity were established from confirmed GOF and LOF variants. An ensemble algorithm was constructed (KCNMA1 Meta Score), consisting of a weighted summation of this trained dataset combined with a structural component derived from the Ca 2+ bound and unbound BK channels. KMS assessment differed from the highest performing individual algorithm (REVEL) at 10 VUS residues, and a subset were studied further by electrophysiology in HEK293 cells. M578T, E656A, and D965V (KMS+;REVEL-) were confirmed to alter BK channel properties in voltage-clamp recordings, and D800Y (KMS-;REVEL+) was assessed as benign under the test conditions. However, KMS failed to accurately assess K457E. These combined results reveal the distribution of potentially disease-causing KCNMA1 variants within BK channel functional domains and pathogenicity evaluation for VUS, suggesting strategies for improving channel-level predictions in future studies by building on ensemble algorithms such as KMS.
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9
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Dinsdale RL, Roache CE, Meredith AL. Disease-associated KCNMA1 variants decrease circadian clock robustness in channelopathy mouse models. J Gen Physiol 2023; 155:e202313357. [PMID: 37728576 PMCID: PMC10510740 DOI: 10.1085/jgp.202313357] [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: 01/30/2023] [Revised: 07/07/2023] [Accepted: 08/24/2023] [Indexed: 09/21/2023] Open
Abstract
KCNMA1 encodes the voltage- and calcium-activated K+ (BK) channel, which regulates suprachiasmatic nucleus (SCN) neuronal firing and circadian behavioral rhythms. Gain-of-function (GOF) and loss-of-function (LOF) alterations in BK channel activity disrupt circadian behavior, but the effect of human disease-associated KCNMA1 channelopathy variants has not been studied on clock function. Here, we assess circadian behavior in two GOF and one LOF mouse lines. Heterozygous Kcnma1N999S/WT and homozygous Kcnma1D434G/D434G mice are validated as GOF models of paroxysmal dyskinesia (PNKD3), but whether circadian rhythm is affected in this hypokinetic locomotor disorder is unknown. Conversely, homozygous LOF Kcnma1H444Q/H444Q mice do not demonstrate PNKD3. We assessed circadian behavior by locomotor wheel running activity. All three mouse models were rhythmic, but Kcnma1N999S/WT and Kcnma1D434G/D434G showed reduced circadian amplitude and decreased wheel activity, corroborating prior studies focused on acute motor coordination. In addition, Kcnma1D434G/D434G mice had a small decrease in period. However, the phase-shifting sensitivity for both GOF mouse lines was abnormal. Both Kcnma1N999S/WT and Kcnma1D434G/D434G mice displayed increased responses to light pulses and took fewer days to re-entrain to a new light:dark cycle. In contrast, the LOF Kcnma1H444Q/H444Q mice showed no difference in any of the circadian parameters tested. The enhanced sensitivity to phase-shifting stimuli in Kcnma1N999S/WT and Kcnma1D434G/D434G mice was similar to other Kcnma1 GOF mice. Together with previous studies, these results suggest that increasing BK channel activity decreases circadian clock robustness, without rhythm ablation.
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Affiliation(s)
- Ria L. Dinsdale
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Cooper E. Roache
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrea L. Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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Rockley K, Roberts R, Jennings H, Jones K, Davis M, Levesque P, Morton M. An integrated approach for early in vitro seizure prediction utilizing hiPSC neurons and human ion channel assays. Toxicol Sci 2023; 196:126-140. [PMID: 37632788 DOI: 10.1093/toxsci/kfad087] [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] [Indexed: 08/28/2023] Open
Abstract
Seizure liability remains a significant cause of attrition throughout drug development. Advances in stem cell biology coupled with an increased understanding of the role of ion channels in seizure offer an opportunity for a new paradigm in screening. We assessed the activity of 15 pro-seizurogenic compounds (7 CNS active therapies, 4 GABA receptor antagonists, and 4 other reported seizurogenic compounds) using automated electrophysiology against a panel of 14 ion channels (Nav1.1, Nav1.2, Nav1.6, Kv7.2/7.3, Kv7.3/7.5, Kv1.1, Kv4.2, KCa4.1, Kv2.1, Kv3.1, KCa1.1, GABA α1β2γ2, nicotinic α4β2, NMDA 1/2A). These were selected based on linkage to seizure in genetic/pharmacological studies. Fourteen compounds demonstrated at least one "hit" against the seizure panel and 11 compounds inhibited 2 or more ion channels. Next, we assessed the impact of the 15 compounds on electrical signaling using human-induced pluripotent stem cell neurons in microelectrode array (MEA). The CNS active therapies (amoxapine, bupropion, chlorpromazine, clozapine, diphenhydramine, paroxetine, quetiapine) all caused characteristic changes to electrical activity in key parameters indicative of seizure such as network burst frequency and duration. The GABA antagonist picrotoxin increased all parameters, but the antibiotics amoxicillin and enoxacin only showed minimal changes. Acetaminophen, included as a negative control, caused no changes in any of the parameters assessed. Overall, pro-seizurogenic compounds showed a distinct fingerprint in the ion channel/MEA panel. These studies highlight the potential utility of an integrated in vitro approach for early seizure prediction to provide mechanistic information and to support optimal drug design in early development, saving time and resources.
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Affiliation(s)
| | - Ruth Roberts
- ApconiX, Macclesfield SK10 4TG, UK
- Department of Biosciences, University of Birmingham, Edgbaston B15 1TT, UK
| | | | | | - Myrtle Davis
- Bristol Myers Squibb, Princeton, New Jersey, USA
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11
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Lin ZJ, Huang BX, Su LF, Zhu SY, He JW, Chen GZ, Lin PX. Sub-region analysis of DMD gene in cases with idiopathic generalized epilepsy. Neurogenetics 2023; 24:161-169. [PMID: 37022522 DOI: 10.1007/s10048-023-00715-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/24/2023] [Indexed: 04/07/2023]
Abstract
Gene sub-region encoded protein domain is the basic unit for protein structure and function. The DMD gene is the largest coding gene in humans, with its phenotype relevant to idiopathic generalized epilepsy. We hypothesized variants clustered in sub-regions of idiopathic generalized epilepsy genes and investigated the relationship between the DMD gene and idiopathic generalized epilepsy. Whole exome sequencing was performed in 106 idiopathic generalized epilepsy individuals. DMD variants were filtered with variant type, allele frequency, in silico prediction, hemizygous or homozygous status in the population, inheritance mode, and domain location. Variants located at the sub-regions were selected by the subRVIS software. The pathogenicity of variants was evaluated by the American College of Medical Genetics and Genomics criteria. Articles on functional studies related to epilepsy for variants clustered protein domains were reviewed. In sub-regions of the DMD gene, two variants were identified in two unrelated cases with juvenile absence epilepsy or juvenile myoclonic epilepsy. The pathogenicity of both variants was uncertain significance. Allele frequency of both variants in probands with idiopathic generalized epilepsy reached statistical significance compared with the population (Fisher's test, p = 2.02 × 10-6, adjusted α = 4.52 × 10-6). The variants clustered in the spectrin domain of dystrophin, which binds to glycoprotein complexes and indirectly affects ion channels contributing to epileptogenesis. Gene sub-region analysis suggests a weak association between the DMD gene and idiopathic generalized epilepsy. Functional analysis of gene sub-region helps infer the pathogenesis of idiopathic generalized epilepsy.
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Affiliation(s)
- Zhi-Jian Lin
- Department of Neurology, The Affiliated Hospital of Putian University, Brain Science Institute of Putian University, 999 Dongzhen East Road, Licheng District, Putian, 351100, China
| | - Bi-Xia Huang
- Department of Neurology, The Affiliated Hospital of Putian University, Brain Science Institute of Putian University, 999 Dongzhen East Road, Licheng District, Putian, 351100, China
| | - Li-Fang Su
- Department of Neurology, The Affiliated Hospital of Putian University, Brain Science Institute of Putian University, 999 Dongzhen East Road, Licheng District, Putian, 351100, China
| | - Sheng-Yin Zhu
- Department of Neurology, The Affiliated Hospital of Putian University, Brain Science Institute of Putian University, 999 Dongzhen East Road, Licheng District, Putian, 351100, China
| | - Jun-Wei He
- Department of Neurology, The Affiliated Hospital of Putian University, Brain Science Institute of Putian University, 999 Dongzhen East Road, Licheng District, Putian, 351100, China
| | - Guo-Zhang Chen
- Department of Neurology, The Affiliated Hospital of Putian University, Brain Science Institute of Putian University, 999 Dongzhen East Road, Licheng District, Putian, 351100, China
| | - Peng-Xing Lin
- Department of Neurology, The Affiliated Hospital of Putian University, Brain Science Institute of Putian University, 999 Dongzhen East Road, Licheng District, Putian, 351100, China.
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12
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Huang H, Shakkottai VG. Targeting Ion Channels and Purkinje Neuron Intrinsic Membrane Excitability as a Therapeutic Strategy for Cerebellar Ataxia. Life (Basel) 2023; 13:1350. [PMID: 37374132 DOI: 10.3390/life13061350] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/03/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
In degenerative neurological disorders such as Parkinson's disease, a convergence of widely varying insults results in a loss of dopaminergic neurons and, thus, the motor symptoms of the disease. Dopamine replacement therapy with agents such as levodopa is a mainstay of therapy. Cerebellar ataxias, a heterogeneous group of currently untreatable conditions, have not been identified to have a shared physiology that is a target of therapy. In this review, we propose that perturbations in cerebellar Purkinje neuron intrinsic membrane excitability, a result of ion channel dysregulation, is a common pathophysiologic mechanism that drives motor impairment and vulnerability to degeneration in cerebellar ataxias of widely differing genetic etiologies. We further propose that treatments aimed at restoring Purkinje neuron intrinsic membrane excitability have the potential to be a shared therapy in cerebellar ataxia akin to levodopa for Parkinson's disease.
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Affiliation(s)
- Haoran Huang
- Medical Scientist Training Program, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Vikram G Shakkottai
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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13
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Yucesan E, Goncu B, Ozgul C, Kebapci A, Aslanger AD, Akyuz E, Yesil G. Functional Characterization of KCNMA1 mutation associated with dyskinesia, seizure, developmental delay, and cerebellar atrophy. Int J Neurosci 2023:1-7. [PMID: 37269313 DOI: 10.1080/00207454.2023.2221814] [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: 05/31/2022] [Revised: 04/26/2023] [Accepted: 05/31/2023] [Indexed: 06/05/2023]
Abstract
KCNMA1 located on chromosome 10q22.3, encodes the pore-forming α subunit of the "Big K+" (BK) large conductance calcium and voltage-activated K + channel. Numerous evidence suggests the functional BK channel alterations produced by different KCNMA1 alleles may associate with different symptoms, such as paroxysmal non kinesigenic dyskinesia with gain of function and ataxia with loss of function. Functional classifications revealed two major patterns, gain of function and loss of function effects on channel properties in different cell lines. In the literature, two mutations have been shown to confer gain of function properties to BK channels: D434G and N995S. In this study, we report the functional characterization of a variant which was previously reported the whole exome sequencing revealed bi-allelic nonsense variation of the cytoplasmic domain of calcium-activated potassium channel subunit alpha-1 protein. To detect functional consequences of the variation, we parallely conducted two independent approaches. One is immunostaining using and the other one is electrophysiological recording using patch-clamp on wild-type and R458X mutant cells to detect the differences between wild-type and the mutant cells. We detected the gain of function effect for the mutation (NM_001161352.1 (ENST00000286628.8):c.1372C > T;Arg458*) using two parallel approaches. According to the result we found, the reported mutation causes the loss of function in the cell. It should be noted that in future studies, it can be thought that the functions of genes associated with channelopathies may have a dual effect such as loss and gain.
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Affiliation(s)
- Emrah Yucesan
- Department of Neurogenetics, Institute of Neurological Sciences, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Beyza Goncu
- Department of Medical Services and Techniques, Vocational School of Health Services, Bezmialem Vakif University, Istanbul, Turkey
- Experimental Research Center, Bezmialem Vakif University, Istanbul, Turkey
| | - Cemil Ozgul
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, Istanbul, Turkey
| | - Arda Kebapci
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, Istanbul, Turkey
| | - Ayca Dilruba Aslanger
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Enes Akyuz
- Department of Biophysics, Faculty of International Medicine, University of Health Sciences, Istanbul, Turkey
| | - Gozde Yesil
- Department of Medical Genetics, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
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14
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Ancatén-González C, Segura I, Alvarado-Sánchez R, Chávez AE, Latorre R. Ca 2+- and Voltage-Activated K + (BK) Channels in the Nervous System: One Gene, a Myriad of Physiological Functions. Int J Mol Sci 2023; 24:3407. [PMID: 36834817 PMCID: PMC9967218 DOI: 10.3390/ijms24043407] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/18/2023] [Accepted: 01/21/2023] [Indexed: 02/11/2023] Open
Abstract
BK channels are large conductance potassium channels characterized by four pore-forming α subunits, often co-assembled with auxiliary β and γ subunits to regulate Ca2+ sensitivity, voltage dependence and gating properties. BK channels are abundantly expressed throughout the brain and in different compartments within a single neuron, including axons, synaptic terminals, dendritic arbors, and spines. Their activation produces a massive efflux of K+ ions that hyperpolarizes the cellular membrane. Together with their ability to detect changes in intracellular Ca2+ concentration, BK channels control neuronal excitability and synaptic communication through diverse mechanisms. Moreover, increasing evidence indicates that dysfunction of BK channel-mediated effects on neuronal excitability and synaptic function has been implicated in several neurological disorders, including epilepsy, fragile X syndrome, mental retardation, and autism, as well as in motor and cognitive behavior. Here, we discuss current evidence highlighting the physiological importance of this ubiquitous channel in regulating brain function and its role in the pathophysiology of different neurological disorders.
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Affiliation(s)
- Carlos Ancatén-González
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
- Programa de Doctorado en Ciencias, Mención Neurociencia, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Ignacio Segura
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Rosangelina Alvarado-Sánchez
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
- Doctorado en Ciencias Mención Biofísica y Biología Computacional, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Andrés E. Chávez
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso (CINV), Instituto de Neurociencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
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15
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Kocaaga A, Yimenicioglu S. Identification of Novel Gene Variants in Children With Drug-Resistant Epilepsy: Expanding the Genetic Spectrum. Pediatr Neurol 2023; 139:7-12. [PMID: 36493596 DOI: 10.1016/j.pediatrneurol.2022.11.005] [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: 07/12/2022] [Revised: 10/09/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022]
Abstract
BACKGROUND Resistance to antiseizure drugs is an important problem in the treatment of individuals with epilepsy. Identifying the molecular etiology of drug-resistant epilepsy (DRE) is crucial for better management of epilepsy. Here, we explore the utility of whole exome sequencing (WES) in identifying causative gene variants in children with DRE. METHODS Forty-five children with DRE who underwent WES tests were included. Genetic examination of all patients included chromosomal analysis and clinical chromosomal microarray followed by WES. The identified variants by WES analysis were classified for pathogenicity based on the American College of Medical Genetics and Genomics guidelines and in silico protein prediction tools. RESULTS The overall diagnostic yield was 55.5% (25 of 45). A total of 26 variants spanning 22 genes were identified in 25 patients. Of note, only 19 of these genes were examined as novel. Ten patients (22.2%) had a pathogenic or likely pathogenic variant. There was a trend associated with a diagnostic genetic test result in girls compared with boys in DRE (P = 0.028). CONCLUSION Our findings expand the mutational spectrum of genes related to DRE. To form disease-specific treatment in children with DRE, the WES analysis should be included in the diagnostic algorithm because of its high diagnostic efficiency.
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Affiliation(s)
- Ayca Kocaaga
- Department of Medical Genetics, Eskisehir City Hospital, Eskişehir, Turkey.
| | - Sevgi Yimenicioglu
- Department of Pediatric Neurology, Eskisehir City Hospital, Eskişehir, Turkey
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16
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Zahra A, Liu R, Han W, Meng H, Wang Q, Wang Y, Campbell SL, Wu J. K Ca-Related Neurological Disorders: Phenotypic Spectrum and Therapeutic Indications. Curr Neuropharmacol 2023; 21:1504-1518. [PMID: 36503451 PMCID: PMC10472807 DOI: 10.2174/1570159x21666221208091805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/21/2022] [Accepted: 07/23/2022] [Indexed: 12/14/2022] Open
Abstract
Although potassium channelopathies have been linked to a wide range of neurological conditions, the underlying pathogenic mechanism is not always clear, and a systematic summary of clinical manifestation is absent. Several neurological disorders have been associated with alterations of calcium-activated potassium channels (KCa channels), such as loss- or gain-of-function mutations, post-transcriptional modification, etc. Here, we outlined the current understanding of the molecular and cellular properties of three subtypes of KCa channels, including big conductance KCa channels (BK), small conductance KCa channels (SK), and the intermediate conductance KCa channels (IK). Next, we comprehensively reviewed the loss- or gain-of-function mutations of each KCa channel and described the corresponding mutation sites in specific diseases to broaden the phenotypic-genotypic spectrum of KCa-related neurological disorders. Moreover, we reviewed the current pharmaceutical strategies targeting KCa channels in KCa-related neurological disorders to provide new directions for drug discovery in anti-seizure medication.
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Affiliation(s)
- Aqeela Zahra
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Department of Zoology, University of Sialkot, Sialkot 51310, Pakistan
| | - Ru Liu
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - Wenzhe Han
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Hui Meng
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - YunFu Wang
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Susan L. Campbell
- Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Jianping Wu
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
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17
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Gao K, Lin Z, Wen S, Jiang Y. Potassium channels and epilepsy. Acta Neurol Scand 2022; 146:699-707. [PMID: 36225112 DOI: 10.1111/ane.13695] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 08/16/2022] [Indexed: 01/10/2023]
Abstract
With the development and application of next-generation sequencing technology, the aetiological diagnosis of genetic epilepsy is rapidly becoming easier and less expensive. Additionally, there is a growing body of research into precision therapy based on genetic diagnosis. The numerous genes in the potassium ion channel family constitute the largest family of ion channels: this family is divided into different subtypes. Potassium ion channels play a crucial role in the electrical activity of neurons and are directly involved in the mechanism of epileptic seizures. In China, scientific research on genetic diagnosis and studies of precision therapy for genetic epilepsy are progressing rapidly. Many cases of epilepsy caused by mutation of potassium channel genes have been identified, and several potassium channel gene targets and drug candidates have been discovered. The purpose of this review is to briefly summarize the progress of research on the precise diagnosis and treatment of potassium ion channel-related genetic epilepsy, especially the research conducted in China. Here in, we review several large cohort studies on the genetic diagnosis of epilepsy in China in recent years, summarized the proportion of potassium channel genes. We focus on the progress of precison therapy on some hot epilepsy related potassium channel genes: KCNA1, KCNA2, KCNB1, KCNC1, KCND2, KCNQ2, KCNQ3, KCNMA1, and KCNT1.
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Affiliation(s)
- Kai Gao
- Department of Pediatrics, Peking University First Hospital, Beijing, China.,Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Beijing, China.,Children Epilepsy Center, Peking University First Hospital, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Zehong Lin
- Department of Neurology, Affiliated Children's Hospital of Capital Institute of Pediatrics, Beijing, China
| | - Sijia Wen
- Department of Pediatrics, Peking University First Hospital, Beijing, China.,Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Beijing, China.,Children Epilepsy Center, Peking University First Hospital, Beijing, China
| | - Yuwu Jiang
- Department of Pediatrics, Peking University First Hospital, Beijing, China.,Beijing Key Laboratory of Molecular Diagnosis and Study on Pediatric Genetic Diseases, Beijing, China.,Children Epilepsy Center, Peking University First Hospital, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China.,Center of Epilepsy, Beijing Institute for Brain Disorders, Beijing, China
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18
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Park SM, Roache CE, Iffland PH, Moldenhauer HJ, Matychak KK, Plante AE, Lieberman AG, Crino PB, Meredith A. BK channel properties correlate with neurobehavioral severity in three KCNMA1-linked channelopathy mouse models. eLife 2022; 11:e77953. [PMID: 35819138 PMCID: PMC9275823 DOI: 10.7554/elife.77953] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 06/01/2022] [Indexed: 12/14/2022] Open
Abstract
KCNMA1 forms the pore of BK K+ channels, which regulate neuronal and muscle excitability. Recently, genetic screening identified heterozygous KCNMA1 variants in a subset of patients with debilitating paroxysmal non-kinesigenic dyskinesia, presenting with or without epilepsy (PNKD3). However, the relevance of KCNMA1 mutations and the basis for clinical heterogeneity in PNKD3 has not been established. Here, we evaluate the relative severity of three KCNMA1 patient variants in BK channels, neurons, and mice. In heterologous cells, BKN999S and BKD434G channels displayed gain-of-function (GOF) properties, whereas BKH444Q channels showed loss-of-function (LOF) properties. The relative degree of channel activity was BKN999S > BKD434G>WT > BKH444Q. BK currents and action potential firing were increased, and seizure thresholds decreased, in Kcnma1N999S/WT and Kcnma1D434G/WT transgenic mice but not Kcnma1H444Q/WT mice. In a novel behavioral test for paroxysmal dyskinesia, the more severely affected Kcnma1N999S/WT mice became immobile after stress. This was abrogated by acute dextroamphetamine treatment, consistent with PNKD3-affected individuals. Homozygous Kcnma1D434G/D434G mice showed similar immobility, but in contrast, homozygous Kcnma1H444Q/H444Q mice displayed hyperkinetic behavior. These data establish the relative pathogenic potential of patient alleles as N999S>D434G>H444Q and validate Kcnma1N999S/WT mice as a model for PNKD3 with increased seizure propensity.
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Affiliation(s)
- Su Mi Park
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Cooper E Roache
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Philip H Iffland
- Department of Neurology, University of Maryland School of MedicineBaltimoreUnited States
| | - Hans J Moldenhauer
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Katia K Matychak
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Amber E Plante
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
| | - Abby G Lieberman
- Department of Pharmacology, University of Maryland School of MedicineBaltimoreUnited States
| | - Peter B Crino
- Department of Neurology, University of Maryland School of MedicineBaltimoreUnited States
| | - Andrea Meredith
- Department of Physiology, University of Maryland School of MedicineBaltimoreUnited States
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19
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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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20
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Liang L, Liu H, Bartholdi D, van Haeringen A, Fernandez‐Jaén A, Peeters EEA, Xiong H, Bai X, Xu C, Ke T, Wang QK. Identification and functional analysis of two new de novo KCNMA1 variants associated with Liang-Wang syndrome. Acta Physiol (Oxf) 2022; 235:e13800. [PMID: 35156297 DOI: 10.1111/apha.13800] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 02/08/2022] [Accepted: 02/11/2022] [Indexed: 02/04/2023]
Abstract
AIM Loss-of-function KCNMA1 variants cause Liang-Wang syndrome (MIM #618729), a newly identified multiple malformation syndrome with a broad spectrum of developmental and neurological phenotypes. However, the full spectrum of clinical features and underlying pathogenic mechanisms need full elucidation. METHODS Exome sequencing was used to identify pathogenic variants. Patch-clamp recordings were performed to access the effects of KCNMA1 variants on BK channels. Total and membrane protein expression levels of BK channels were characterized using Western blotting. RESULTS We report identification and functional characterization of two new de novo loss-of-function KCNMA1 variants p.(A172T) and p.(A314T) with characteristics of Liang-Wang syndrome. Variant p.(A172T) is associated with developmental delay, cognitive impairment and ataxia. Mechanistically, p.(A172T) abolishes BK potassium current, inhibits Mg2+ -dependent gating, but shifts conductance-voltage (G-V) curves to more positive potentials when complexed with WT channels. Variant p.(A314T) is associated with developmental delay, intellectual disability, cognitive impairment, mild ataxia and generalized epilepsy; suppresses BK current amplitude; and shifts G-V curves to more positive potentials when expressed with WT channels. In addition, two new patients with previously reported gain-of-function variants p.(N536H) and p.(N995S) are found to show epilepsy and paroxysmal dyskinesia as reported previously, but also exhibit additional symptoms of cognitive impairment and dysmorphic features. Furthermore, variants p.(A314T) and p.(N536H) reduced total and membrane levels of BK proteins. CONCLUSION Our findings identified two new loss-of-function mutations of KCNMA1 associated with Liang-Wang syndrome, expanded the spectrum of clinical features associated with gain-of-function KCNMA1 variants and emphasized the overlapping features shared by gain-of-function and loss-of-function mutations.
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Affiliation(s)
- Lina Liang
- Center for Human Genome Research Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology Wuhan P. R. China
| | - Huihui Liu
- Center for Human Genome Research Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology Wuhan P. R. China
| | - Deborah Bartholdi
- Department of Human Genetics, Inselspital University Hospital Bern Bern Switzerland
| | - Arie van Haeringen
- Department of Clinical Genetics Leiden University Medical Center Leiden the Netherlands
| | - Alberto Fernandez‐Jaén
- Hospital Universitario Quirónsalud School of Medicine Universidad Europea de Madrid Madrid Spain
| | - Els E. A. Peeters
- Department of Child Neurology Juliana Children’s Hospital HAGA Medical Center The Hague the Netherlands
| | - Hongbo Xiong
- Center for Human Genome Research Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology Wuhan P. R. China
| | - Xuemei Bai
- Center for Human Genome Research Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology Wuhan P. R. China
| | - Chengqi Xu
- Center for Human Genome Research Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology Wuhan P. R. China
| | - Tie Ke
- Center for Human Genome Research Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology Wuhan P. R. China
| | - Qing K. Wang
- Center for Human Genome Research Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology Wuhan P. R. China
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21
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Ozerov M, Noreikiene K, Kahar S, Huss M, Huusko A, Kõiv T, Sepp M, López M, Gårdmark A, Gross R, Vasemägi A. Whole-genome sequencing illuminates multifaceted targets of selection to humic substances in Eurasian perch. Mol Ecol 2022; 31:2367-2383. [PMID: 35202502 PMCID: PMC9314028 DOI: 10.1111/mec.16409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 02/10/2022] [Accepted: 02/17/2022] [Indexed: 11/30/2022]
Abstract
Extreme environments are inhospitable to the majority of species, but some organisms are able to survive in such hostile conditions due to evolutionary adaptations. For example, modern bony fishes have colonized various aquatic environments, including perpetually dark, hypoxic, hypersaline and toxic habitats. Eurasian perch (Perca fluviatilis) is among the few fish species of northern latitudes that is able to live in very acidic humic lakes. Such lakes represent almost "nocturnal" environments; they contain high levels of dissolved organic matter, which in addition to creating a challenging visual environment, also affects a large number of other habitat parameters and biotic interactions. To reveal the genomic targets of humic-associated selection, we performed whole-genome sequencing of perch originating from 16 humic and 16 clear-water lakes in northern Europe. We identified over 800,000 single nucleotide polymorphisms, of which >10,000 were identified as potential candidates under selection (associated with >3000 genes) using multiple outlier approaches. Our findings suggest that adaptation to the humic environment may involve hundreds of regions scattered across the genome. Putative signals of adaptation were detected in genes and gene families with diverse functions, including organism development and ion transportation. The observed excess of variants under selection in regulatory regions highlights the importance of adaptive evolution via regulatory elements, rather than via protein sequence modification. Our study demonstrates the power of whole-genome analysis to illuminate the multifaceted nature of humic adaptation and provides the foundation for further investigation of causal mutations underlying phenotypic traits of ecological and evolutionary importance.
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Affiliation(s)
- Mikhail Ozerov
- Department of Aquatic ResourcesInstitute of Freshwater ResearchSwedish University of Agricultural SciencesDrottningholmSweden
- Department of BiologyUniversity of TurkuTurkuFinland
- Biodiversity UnitUniversity of TurkuTurkuFinland
| | - Kristina Noreikiene
- Chair of AquacultureInstitute of Veterinary Medicine and Animal SciencesEstonian University of Life SciencesTartuEstonia
| | - Siim Kahar
- Chair of AquacultureInstitute of Veterinary Medicine and Animal SciencesEstonian University of Life SciencesTartuEstonia
| | - Magnus Huss
- Department of Aquatic ResourcesSwedish University of Agricultural SciencesÖregrundSweden
| | - Ari Huusko
- Natural resources Institute Finland (Luke)PaltamoFinland
| | - Toomas Kõiv
- Chair of Hydrobiology and FisheryInstitute of Agricultural and Environmental SciencesEstonian University of Life SciencesTartuEstonia
| | - Margot Sepp
- Chair of Hydrobiology and FisheryInstitute of Agricultural and Environmental SciencesEstonian University of Life SciencesTartuEstonia
| | - María‐Eugenia López
- Department of Aquatic ResourcesInstitute of Freshwater ResearchSwedish University of Agricultural SciencesDrottningholmSweden
| | - Anna Gårdmark
- Department of Aquatic ResourcesSwedish University of Agricultural SciencesÖregrundSweden
| | - Riho Gross
- Chair of AquacultureInstitute of Veterinary Medicine and Animal SciencesEstonian University of Life SciencesTartuEstonia
| | - Anti Vasemägi
- Department of Aquatic ResourcesInstitute of Freshwater ResearchSwedish University of Agricultural SciencesDrottningholmSweden
- Chair of AquacultureInstitute of Veterinary Medicine and Animal SciencesEstonian University of Life SciencesTartuEstonia
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22
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Dong P, Zhang Y, Hunanyan AS, Mikati MA, Cui J, Yang H. Neuronal mechanism of a BK channelopathy in absence epilepsy and dyskinesia. Proc Natl Acad Sci U S A 2022; 119:e2200140119. [PMID: 35286197 PMCID: PMC8944272 DOI: 10.1073/pnas.2200140119] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/02/2022] [Indexed: 12/13/2022] Open
Abstract
A growing number of gain-of-function (GOF) BK channelopathies have been identified in patients with epilepsy and movement disorders. Nevertheless, the underlying pathophysiology and corresponding therapeutics remain obscure. Here, we utilized a knock-in mouse model carrying human BK-D434G channelopathy to investigate the neuronal mechanism of BK GOF in the pathogenesis of epilepsy and dyskinesia. The BK-D434G mice manifest the clinical features of absence epilepsy and exhibit severe motor deficits and dyskinesia-like behaviors. The cortical pyramidal neurons and cerebellar Purkinje cells from the BK-D434G mice show hyperexcitability, which likely contributes to the pathogenesis of absence seizures and paroxysmal dyskinesia. A BK channel blocker, paxilline, potently suppresses BK-D434G–induced hyperexcitability and effectively mitigates absence seizures and locomotor deficits in mice. Our study thus uncovered a neuronal mechanism of BK GOF in absence epilepsy and dyskinesia. Our findings also suggest that BK inhibition is a promising therapeutic strategy for mitigating BK GOF-induced neurological disorders.
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Affiliation(s)
- Ping Dong
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
| | - Yang Zhang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
| | - Arsen S. Hunanyan
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
| | - Mohamad A. Mikati
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO 63130
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710
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23
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Yang C, Yang Z, Tong K, Wang J, Yang W, Yu R, Jiang F, Ji Y. Homology modeling and molecular docking simulation of martentoxin as a specific inhibitor of the BK channel. ANNALS OF TRANSLATIONAL MEDICINE 2022; 10:71. [PMID: 35282126 PMCID: PMC8848368 DOI: 10.21037/atm-21-6967] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 01/13/2022] [Indexed: 11/18/2022]
Abstract
Background Large conductance calcium-activated potassium channel (BK channel) is gated by both voltage and calcium ions and is widely distributed in excitable and nonexcitable cells. BK channel plays an important role in epilepsy and other diseases, but BK channel subtype-specific drugs are still extremely rare. Martentoxin was previously isolated from the venom of members of Scorpionidae and shown to be composed of 37 amino acids. Research has shown that the pharmacological selectivity of martentoxin to the BK channel is higher than that to other potassium channels. Therefore, it is of great significance to study the mechanism of interaction between martentoxin and BK channels. Methods The three-dimensional structure of BK channel pore region was constructed by homologous modeling method, and the key amino acid sites of BK channel interaction with martentoxin were analyzed by protein-protein docking, molecular dynamic simulation and virtual alanine mutation. Results Based on homologous modeling of BK channel pore structure and protein-protein docking analysis, Phe1, Lys28 and Arg35 of martentoxin were found to be key amino acids in toxin BK channel interaction. Conclusions This study reveals the structural basis of martentoxin interaction with BK channel. These results will contribute to the design of BK channel specific blockers based on the structure of martentoxin.
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Affiliation(s)
- Chao Yang
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Zihao Yang
- College of Life Sciences and Food Engineering, Huaiyin Institute of Technology, Huai'an, China
| | - Kuiyuan Tong
- College of Life Sciences and Food Engineering, Huaiyin Institute of Technology, Huai'an, China
| | - Jiawei Wang
- School of Life and Medicine Sciences, Shanghai University, Shanghai, China
| | - Wanli Yang
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Ruihua Yu
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Feng Jiang
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China
| | - Yonghua Ji
- Translational Institute for Cancer Pain, Chongming Hospital Affiliated to Shanghai University of Medicine and Health Sciences (Xinhua Hospital Chongming Branch), Shanghai, China.,School of Life and Medicine Sciences, Shanghai University, Shanghai, China
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24
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Zou D, Wang L, Liao J, Xiao H, Duan J, Zhang T, Li J, Yin Z, Zhou J, Yan H, Huang Y, Zhan N, Yang Y, Ye J, Chen F, Zhu S, Wen F, Guo J. Genome sequencing of 320 Chinese children with epilepsy: a clinical and molecular study. Brain 2021; 144:3623-3634. [PMID: 34145886 PMCID: PMC8719847 DOI: 10.1093/brain/awab233] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 05/25/2021] [Accepted: 06/05/2021] [Indexed: 02/05/2023] Open
Abstract
The aim of this study is to evaluate the diagnostic value of genome sequencing in children with epilepsy, and to provide genome sequencing-based insights into the molecular genetic mechanisms of epilepsy to help establish accurate diagnoses, design appropriate treatments and assist in genetic counselling. We performed genome sequencing on 320 Chinese children with epilepsy, and interpreted single-nucleotide variants and copy number variants of all samples. The complete pedigree and clinical data of the probands were established and followed up. The clinical phenotypes, treatments, prognoses and genotypes of the patients were analysed. Age at seizure onset ranged from 1 day to 17 years, with a median of 4.3 years. Pathogenic/likely pathogenic variants were found in 117 of the 320 children (36.6%), of whom 93 (29.1%) had single-nucleotide variants, 22 (6.9%) had copy number variants and two had both single-nucleotide variants and copy number variants. Single-nucleotide variants were most frequently found in SCN1A (10/95, 10.5%), which is associated with Dravet syndrome, followed by PRRT2 (8/95, 8.4%), which is associated with benign familial infantile epilepsy, and TSC2 (7/95, 7.4%), which is associated with tuberous sclerosis. Among the copy number variants, there were three with a length <25 kilobases. The most common recurrent copy number variants were 17p13.3 deletions (5/24, 20.8%), 16p11.2 deletions (4/24, 16.7%), and 7q11.23 duplications (2/24, 8.3%), which are associated with epilepsy, developmental retardation and congenital abnormalities. Four particular 16p11.2 deletions and two 15q11.2 deletions were considered to be susceptibility factors contributing to neurodevelopmental disorders associated with epilepsy. The diagnostic yield was 75.0% in patients with seizure onset during the first postnatal month, and gradually decreased in patients with seizure onset at a later age. Forty-two patients (13.1%) were found to be specifically treatable for the underlying genetic cause identified by genome sequencing. Three of them received corresponding targeted therapies and demonstrated favourable prognoses. Genome sequencing provides complete genetic diagnosis, thus enabling individualized treatment and genetic counselling for the parents of the patients. Genome sequencing is expected to become the first choice of methods for genetic testing of patients with epilepsy.
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Affiliation(s)
- Dongfang Zou
- Department of Neurology, Shenzhen Children’s Hospital, Shenzhen, China
| | - Lin Wang
- BGI-Shenzhen, Shenzhen 518083, China
| | - Jianxiang Liao
- Department of Neurology, Shenzhen Children’s Hospital, Shenzhen, China
| | | | - Jing Duan
- Department of Neurology, Shenzhen Children’s Hospital, Shenzhen, China
| | | | | | | | - Jing Zhou
- BGI-Shenzhen, Shenzhen 518083, China
| | | | | | | | - Ying Yang
- BGI-Shenzhen, Shenzhen 518083, China
| | - Jingyu Ye
- BGI-Shenzhen, Shenzhen 518083, China
| | - Fang Chen
- BGI-Shenzhen, Shenzhen 518083, China
| | - Shida Zhu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Feiqiu Wen
- Department of Hematology and Oncology, Shenzhen Children’s Hospital, Shenzhen, China
- Correspondence may also be addressed to: Feiqiu Wen Shenzhen Children’s Hospital No. 7019 Yitian Road, Shenzhen 518038 Guangdong, China E-mail:
| | - Jian Guo
- BGI-Shenzhen, Shenzhen 518083, China
- Correspondence to: Jian Guo BGI-Shenzhen, Beishan Industry Zone Shenzhen 518083, Guangdong, China E-mail:
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25
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Miller JP, Moldenhauer HJ, Keros S, Meredith AL. An emerging spectrum of variants and clinical features in KCNMA1-linked channelopathy. Channels (Austin) 2021; 15:447-464. [PMID: 34224328 PMCID: PMC8259716 DOI: 10.1080/19336950.2021.1938852] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/18/2021] [Accepted: 06/01/2021] [Indexed: 12/13/2022] Open
Abstract
KCNMA1-linked channelopathy is an emerging neurological disorder characterized by heterogeneous and overlapping combinations of movement disorder, seizure, developmental delay, and intellectual disability. KCNMA1 encodes the BK K+ channel, which contributes to both excitatory and inhibitory neuronal and muscle activity. Understanding the basis of the disorder is an important area of active investigation; however, the rare prevalence has hampered the development of large patient cohorts necessary to establish genotype-phenotype correlations. In this review, we summarize 37 KCNMA1 alleles from 69 patients currently defining the channelopathy and assess key diagnostic and clinical hallmarks. At present, 3 variants are classified as gain-of-function with respect to BK channel activity, 14 loss-of-function, 15 variants of uncertain significance, and putative benign/VUS. Symptoms associated with these variants were curated from patient-provided information and prior publications to define the spectrum of clinical phenotypes. In this newly expanded cohort, seizures showed no differential distribution between patients harboring GOF and LOF variants, while movement disorders segregated by mutation type. Paroxysmal non-kinesigenic dyskinesia was predominantly observed among patients with GOF alleles of the BK channel, although not exclusively so, while additional movement disorders were observed in patients with LOF variants. Neurodevelopmental and structural brain abnormalities were prevalent in patients with LOF mutations. In contrast to mutations, disease-associated KCNMA1 single nucleotide polymorphisms were not predominantly related to neurological phenotypes but covered a wider set of peripheral physiological functions. Together, this review provides additional evidence exploring the genetic and biochemical basis for KCNMA1-linked channelopathy and summarizes the clinical repository of patient symptoms across multiple types of KCNMA1 gene variants.
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Affiliation(s)
- Jacob P. Miller
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hans J. Moldenhauer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sotirios Keros
- Department of Pediatrics, Weill Cornell Medical College, New York, NY, USA
| | - Andrea L. Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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26
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Cui J. BK Channel Gating Mechanisms: Progresses Toward a Better Understanding of Variants Linked Neurological Diseases. Front Physiol 2021; 12:762175. [PMID: 34744799 PMCID: PMC8567085 DOI: 10.3389/fphys.2021.762175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 10/01/2021] [Indexed: 12/21/2022] Open
Abstract
The large conductance Ca2+-activated potassium (BK) channel is activated by both membrane potential depolarization and intracellular Ca2+ with distinct mechanisms. Neural physiology is sensitive to the function of BK channels, which is shown by the discoveries of neurological disorders that are associated with BK channel mutations. This article reviews the molecular mechanisms of BK channel activation in response to voltage and Ca2+ binding, including the recent progress since the publication of the atomistic structure of the whole BK channel protein, and the neurological disorders associated with BK channel mutations. These results demonstrate the unique mechanisms of BK channel activation and that these mechanisms are important factors in linking BK channel mutations to neurological disorders.
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Affiliation(s)
- Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO, United States
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27
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Rodrigues Bento J, Feben C, Kempers M, van Rij M, Woiski M, Devriendt K, De Catte L, Baldewijns M, Alaerts M, Meester J, Verstraeten A, Hendson W, Loeys B. Two novel presentations of KCNMA1-related pathology--Expanding the clinical phenotype of a rare channelopathy. Mol Genet Genomic Med 2021; 9:e1797. [PMID: 34499417 PMCID: PMC8580096 DOI: 10.1002/mgg3.1797] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 05/19/2021] [Accepted: 08/13/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND KCNMA1 mutations have recently been associated with a wide range of dysmorphological, gastro-intestinal, cardiovascular, and neurological manifestations. METHODS Whole exome sequencing was performed in order to identify the underlying pathogenic mutation in two cases presenting with diverse phenotypical manifestations that did not fit into well-known clinical entities. RESULTS In an 8-year-old boy presenting with severe aortic dilatation, facial dysmorphism, and overgrowth at birth a de novo p.Gly375Arg KCNMA1 mutation was identified which has been reported previously in association with gingival hypertrophy, aortic dilatation, and developmental delay. Additionally, in a 30-week-old fetus with severe growth retardation and duodenal atresia a de novo p.Pro805Leu KCNMA1 mutation was identified. The latter has also been reported before in a boy with severe neurological manifestations, including speech delay, developmental delay, and cerebellar dysfunction. CONCLUSION The current report presents the first antenatal presentation of a pathogenic KCNMA1 mutation and confirms the specific association of the p.Gly375Arg variant with early onset aortic root dilatation, gingival hypertrophy, and neonatal overgrowth.
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Affiliation(s)
- Jotte Rodrigues Bento
- Centre of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Candice Feben
- Division of Human Genetics, National Health Laboratory Service & The School of Pathology, University of the Witwatersrand, Johannesburg-Braamfontein, South Africa
| | - Marlies Kempers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maartje van Rij
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Gynaecology and Obstetrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Mallory Woiski
- Department of Gynaecology and Obstetrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Koenraad Devriendt
- Department of Human Genetics, Catholic University of Leuven, Leuven, Belgium
| | - Luc De Catte
- Department of Gynaecology and Obstetrics, Catholic University of Leuven, Leuven, Belgium
| | - Marcella Baldewijns
- Department of Gynaecology and Obstetrics, Catholic University of Leuven, Leuven, Belgium
| | - Maaike Alaerts
- Centre of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Josephina Meester
- Centre of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Aline Verstraeten
- Centre of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Willy Hendson
- Department of Paediatrics, Rahima Moosa Mother and Child Hospital & The University of the Witwatersrand, Johannesburg-Braamfontein, South Africa
| | - Bart Loeys
- Centre of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
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28
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Zhu J, Chen F, Luo L, Wu W, Dai J, Zhong J, Lin X, Chai C, Ding P, Liang L, Wang S, Ding X, Chen Y, Wang H, Qiu J, Wang F, Sun C, Zeng Y, Fang J, Jiang X, Liu P, Tang G, Qiu X, Zhang X, Ruan Y, Jiang S, Li J, Zhu S, Xu X, Li F, Liu Z, Cao G, Chen D. Single-cell atlas of domestic pig cerebral cortex and hypothalamus. Sci Bull (Beijing) 2021; 66:1448-1461. [PMID: 36654371 DOI: 10.1016/j.scib.2021.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 11/07/2020] [Accepted: 03/12/2021] [Indexed: 01/20/2023]
Abstract
The brain of the domestic pig (Sus scrofa domesticus) has drawn considerable attention due to its high similarities to that of humans. However, the cellular compositions of the pig brain (PB) remain elusive. Here we investigated the single-nucleus transcriptomic profiles of five regions of the PB (frontal lobe, parietal lobe, temporal lobe, occipital lobe, and hypothalamus) and identified 21 cell subpopulations. The cross-species comparison of mouse and pig hypothalamus revealed the shared and specific gene expression patterns at the single-cell resolution. Furthermore, we identified cell types and molecular pathways closely associated with neurological disorders, bridging the gap between gene mutations and pathogenesis. We reported, to our knowledge, the first single-cell atlas of domestic pig cerebral cortex and hypothalamus combined with a comprehensive analysis across species, providing extensive resources for future research regarding neural science, evolutionary developmental biology, and regenerative medicine.
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Affiliation(s)
- Jiacheng Zhu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Fang Chen
- BGI-Shenzhen, Shenzhen 518083, China; MGI, BGI-Shenzhen, Shenzhen 518083, China
| | - Lihua Luo
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Weiying Wu
- BGI-Shenzhen, Shenzhen 518083, China; Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, School of Brain Science and Brian Medicine, and the MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Medicine, Hangzhou 310031, China
| | - Jinxia Dai
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Jixing Zhong
- School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China
| | - Xiumei Lin
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Chaochao Chai
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Peiwen Ding
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Langchao Liang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Shiyou Wang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Xiangning Ding
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Yin Chen
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Haoyu Wang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Jiaying Qiu
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | | | - Chengcheng Sun
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China; School of Basic Medicine, Qingdao University, Qingdao 266071, China
| | - Yuying Zeng
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China; College of Life Science, South China Agricultural University, Guangzhou 510642, China
| | - Jian Fang
- BGI-Shenzhen, Shenzhen 518083, China
| | - Xiaosen Jiang
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; BGI-Shenzhen, Shenzhen 518083, China
| | - Ping Liu
- BGI-Shenzhen, Shenzhen 518083, China; MGI, BGI-Shenzhen, Shenzhen 518083, China
| | - Gen Tang
- Shenzhen Children's Hospital, Shenzhen 518083, China
| | - Xin Qiu
- Shenzhen Children's Hospital, Shenzhen 518083, China
| | | | - Yetian Ruan
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | | | | | - Shida Zhu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Xun Xu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Fang Li
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Zhongmin Liu
- Research Center for Translational Medicine, East Hospital, Tongji University School of Medicine, Shanghai 200120, China
| | - Gang Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China; College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; College of Biomedicine and Health, Huazhong Agricultural University, Wuhan 430070, China.
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29
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Mutations and Protein Interaction Landscape Reveal Key Cellular Events Perturbed in Upper Motor Neurons with HSP and PLS. Brain Sci 2021; 11:brainsci11050578. [PMID: 33947096 PMCID: PMC8146506 DOI: 10.3390/brainsci11050578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 01/06/2023] Open
Abstract
Hereditary spastic paraplegia (HSP) and primary lateral sclerosis (PLS) are rare motor neuron diseases, which affect mostly the upper motor neurons (UMNs) in patients. The UMNs display early vulnerability and progressive degeneration, while other cortical neurons mostly remain functional. Identification of numerous mutations either directly linked or associated with HSP and PLS begins to reveal the genetic component of UMN diseases. Since each of these mutations are identified on genes that code for a protein, and because cellular functions mostly depend on protein-protein interactions, we hypothesized that the mutations detected in patients and the alterations in protein interaction domains would hold the key to unravel the underlying causes of their vulnerability. In an effort to bring a mechanistic insight, we utilized computational analyses to identify interaction partners of proteins and developed the protein-protein interaction landscape with respect to HSP and PLS. Protein-protein interaction domains, upstream regulators and canonical pathways begin to highlight key cellular events. Here we report that proteins involved in maintaining lipid homeostasis and cytoarchitectural dynamics and their interactions are of great importance for UMN health and stability. Their perturbation may result in neuronal vulnerability, and thus maintaining their balance could offer therapeutic interventions.
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30
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Nikitin ES, Vinogradova LV. Potassium channels as prominent targets and tools for the treatment of epilepsy. Expert Opin Ther Targets 2021; 25:223-235. [PMID: 33754930 DOI: 10.1080/14728222.2021.1908263] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION K+ channels are of great interest to epilepsy research as mutations in their genes are found in humans with inherited epilepsy. At the level of cellular physiology, K+ channels control neuronal intrinsic excitability and are the main contributors to membrane repolarization of active neurons. Recently, a genetically modified voltage-dependent K+ channel has been patented as a remedy for epileptic seizures. AREAS COVERED We review the role of potassium channels in excitability, clinical and experimental evidence for the association of potassium channelopathies with epilepsy, the targeting of K+ channels by drugs, and perspectives of gene therapy in epilepsy with the expression of extra K+ channels in the brain. EXPERT OPINION Control over K+ conductance is of great potential benefit for the treatment of epilepsy. Nowadays, gene therapy affecting K+ channels is one of the most promising approaches to treat pharmacoresistant focal epilepsy.
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Affiliation(s)
- E S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - L V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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31
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Szeto RA, Tran T, Truong J, Negraes PD, Trujillo CA. RNA processing in neurological tissue: development, aging and disease. Semin Cell Dev Biol 2020; 114:57-67. [PMID: 33077405 DOI: 10.1016/j.semcdb.2020.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 07/29/2020] [Accepted: 09/07/2020] [Indexed: 12/13/2022]
Abstract
Gene expression comprises a diverse array of enzymes, proteins, non-coding transcripts, and cellular structures to guide the transfer of genetic information to its various final products. In the brain, the coordination among genes, or lack thereof, characterizes individual brain regions, mediates a variety of brain-related disorders, and brings light to fundamental differences between species. RNA processing, occurring between transcription and translation, controls an essential portion of gene expression through splicing, editing, localization, stability, and interference. The machinery to regulate transcripts must operate with precision serving as a blueprint for proteins and non-coding RNAs to derive their identity. Therefore, RNA processing has a broad scope of influence in the brain, as it modulates cell morphogenesis during development and underlies mechanisms behind certain neurological diseases. Here, we present these ideas through recent findings on RNA processing in development and post-developmental maturity to advance therapeutic discoveries and the collective knowledge of the RNA life cycle.
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Affiliation(s)
- Ryan A Szeto
- Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA 92037, USA
| | - Timothy Tran
- Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA 92037, USA
| | - Justin Truong
- Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA 92037, USA
| | - Priscilla D Negraes
- Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA 92037, USA
| | - Cleber A Trujillo
- Department of Pediatrics, School of Medicine, University of California San Diego, La Jolla, CA 92037, USA.
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32
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Heim J, Vemuri A, Lewis S, Guida B, Troester M, Keros S, Meredith A, Kruer MC. Cataplexy in Patients Harboring the KCNMA1 p.N999S Mutation. Mov Disord Clin Pract 2020; 7:861-862. [PMID: 33043086 DOI: 10.1002/mdc3.13024] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 05/04/2020] [Accepted: 05/25/2020] [Indexed: 01/21/2023] Open
Affiliation(s)
- Jennifer Heim
- Pediatric Movement Disorders Program, Barrow Neurological Institute Phoenix Children's Hospital Phoenix Arizona USA
| | - Anusha Vemuri
- Pathology Department University of Chicago Medical Center Chicago Illinois USA
| | - Sara Lewis
- Pediatric Movement Disorders Program, Barrow Neurological Institute Phoenix Children's Hospital Phoenix Arizona USA.,Departments of Child Health, Neurology, Genetics, Cellular & Molecular Medicine University of Arizona College of Medicine Phoenix Phoenix Arizona USA
| | - Brandon Guida
- Pediatric Movement Disorders Program, Barrow Neurological Institute Phoenix Children's Hospital Phoenix Arizona USA.,Departments of Child Health, Neurology, Genetics, Cellular & Molecular Medicine University of Arizona College of Medicine Phoenix Phoenix Arizona USA
| | - Matthew Troester
- Pediatric Epilepsy & Sleep Medicine Program, Barrow Neurological Institute Phoenix Children's Hospital Phoenix Arizona USA
| | - Sotirios Keros
- New York Presbyterian Hospital Weill Cornell Medical Center New York New York City USA
| | - Andrea Meredith
- University of Maryland School of Medicine Baltimore Maryland USA
| | - Michael C Kruer
- Pediatric Movement Disorders Program, Barrow Neurological Institute Phoenix Children's Hospital Phoenix Arizona USA.,Departments of Child Health, Neurology, Genetics, Cellular & Molecular Medicine University of Arizona College of Medicine Phoenix Phoenix Arizona USA
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33
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Zhang G, Gibson RA, McDonald M, Liang P, Kang PW, Shi J, Yang H, Cui J, Mikati MA. A Gain-of-Function Mutation in KCNMA1 Causes Dystonia Spells Controlled With Stimulant Therapy. Mov Disord 2020; 35:1868-1873. [PMID: 32633875 DOI: 10.1002/mds.28138] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 05/08/2020] [Accepted: 05/15/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The mutations of KCNMA1 BK-type K+ channel have been identified in patients with various movement disorders. The underlying pathophysiology and corresponding therapeutics are lacking. OBJECTIVES To report our clinical and biophysical characterizations of a novel de novo KCNMA1 variant, as well as an effective therapy for the patient's dystonia-atonia spells. METHODS Combination of phenotypic characterization, therapy, and biophysical characterization of the patient and her mutation. RESULTS The patient had >100 dystonia-atonia spells per day with mild cerebellar atrophy. She also had autism spectrum disorder, intellectual disability, and attention deficit hyperactivity disorder. Whole-exome sequencing identified a heterozygous de novo BK N536H mutation. Our biophysical characterization demonstrates that N536H is a gain-of-function mutation with markedly enhanced voltage-dependent activation. Remarkably, administration of dextroamphetamine completely suppressed the dystonia-atonia spells. CONCLUSIONS BK N536H is a gain-of-function that causes dystonia and other neurological symptoms. Our stimulant therapy opens a new avenue to mitigate KCNMA1-linked movement disorders. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Guohui Zhang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Rebecca A Gibson
- Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Marie McDonald
- Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Pengfei Liang
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA
| | - Po Wei Kang
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA.,Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Jianmin Cui
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Mohamad A Mikati
- Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA.,Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA
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Liang L, Li X, Moutton S, Schrier Vergano SA, Cogné B, Saint-Martin A, Hurst ACE, Hu Y, Bodamer O, Thevenon J, Hung CY, Isidor B, Gerard B, Rega A, Nambot S, Lehalle D, Duffourd Y, Thauvin-Robinet C, Faivre L, Bézieau S, Dure LS, Helbling DC, Bick D, Xu C, Chen Q, Mancini GMS, Vitobello A, Wang QK. De novo loss-of-function KCNMA1 variants are associated with a new multiple malformation syndrome and a broad spectrum of developmental and neurological phenotypes. Hum Mol Genet 2020; 28:2937-2951. [PMID: 31152168 DOI: 10.1093/hmg/ddz117] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/17/2019] [Accepted: 05/21/2019] [Indexed: 02/06/2023] Open
Abstract
KCNMA1 encodes the large-conductance Ca2+- and voltage-activated K+ (BK) potassium channel α-subunit, and pathogenic gain-of-function variants in this gene have been associated with a dominant form of generalized epilepsy and paroxysmal dyskinesia. Here, we genetically and functionally characterize eight novel loss-of-function (LoF) variants of KCNMA1. Genome or exome sequencing and the participation in the international Matchmaker Exchange effort allowed for the identification of novel KCNMA1 variants. Patch clamping was used to assess functionality of mutant BK channels. The KCNMA1 variants p.(Ser351Tyr), p.(Gly356Arg), p.(Gly375Arg), p.(Asn449fs) and p.(Ile663Val) abolished the BK current, whereas p.(Cys413Tyr) and p.(Pro805Leu) reduced the BK current amplitude and shifted the activation curves toward positive potentials. The p.(Asp984Asn) variant reduced the current amplitude without affecting kinetics. A phenotypic analysis of the patients carrying the recurrent p.(Gly375Arg) de novo missense LoF variant revealed a novel syndromic neurodevelopmental disorder associated with severe developmental delay, visceral and cardiac malformations, connective tissue presentations with arterial involvement, bone dysplasia and characteristic dysmorphic features. Patients with other LoF variants presented with neurological and developmental symptoms including developmental delay, intellectual disability, ataxia, axial hypotonia, cerebral atrophy and speech delay/apraxia/dysarthria. Therefore, LoF KCNMA1 variants are associated with a new syndrome characterized by a broad spectrum of neurological phenotypes and developmental disorders. LoF variants of KCNMA1 cause a new syndrome distinctly different from gain-of-function variants in the same gene.
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Affiliation(s)
- Lina Liang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P. R. China
| | - Xia Li
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P. R. China
| | - Sébastien Moutton
- Centre de Référence Anomalies du Développement et Syndromes Malformatifs, Hôpital d'Enfants, Dijon 21079, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital d'Enfants, Dijon 21079, France.,Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Samantha A Schrier Vergano
- Medical Genetics and Metabolism, Children's Hospital of The King's Daughters, Eastern Virginia Medical School, Norfolk, VA 23507, USA
| | - Benjamin Cogné
- Service de Génétique Médicale, CHU de Nantes, Nantes 44093, France
| | - Anne Saint-Martin
- Neuropédiatrie, Centre de Référence des Epilepsies Rares, Hôpitaux Universitaires de Strasbourg, Strasbourg 67098, France
| | - Anna C E Hurst
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Yushuang Hu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P. R. China
| | - Olaf Bodamer
- Division of Genetics and Genomics, Boston Children's Hospital/Harvard Medical School, Boston, MA 02115, USA.,The Broad Institute of Harvard and MIT, Boston, MA 02115, USA
| | - Julien Thevenon
- Centre de Référence Anomalies du Développement et Syndromes Malformatifs, Hôpital d'Enfants, Dijon 21079, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital d'Enfants, Dijon 21079, France.,Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Christina Y Hung
- Division of Genetics and Genomics, Boston Children's Hospital/Harvard Medical School, Boston, MA 02115, USA
| | - Bertrand Isidor
- Service de Génétique Médicale, CHU de Nantes, Nantes 44093, France
| | - Bénédicte Gerard
- Institut de Génétique Médicale d'Alsace, Laboratoires de Diagnostic Génétique, Unité de Génétique Moléculaire, Nouvel Hôpital Civil, Strasbourg 67000, Franc
| | - Adelaide Rega
- Pediatric Radiologist, Département de Radiologie et Imagerie Diagnostique et Thérapeutique, CHU, Dijon 21079, France
| | - Sophie Nambot
- Centre de Référence Anomalies du Développement et Syndromes Malformatifs, Hôpital d'Enfants, Dijon 21079, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital d'Enfants, Dijon 21079, France.,Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Daphné Lehalle
- Centre de Référence Anomalies du Développement et Syndromes Malformatifs, Hôpital d'Enfants, Dijon 21079, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital d'Enfants, Dijon 21079, France.,Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Yannis Duffourd
- Centre de Référence Anomalies du Développement et Syndromes Malformatifs, Hôpital d'Enfants, Dijon 21079, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital d'Enfants, Dijon 21079, France.,Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Christel Thauvin-Robinet
- Centre de Référence Anomalies du Développement et Syndromes Malformatifs, Hôpital d'Enfants, Dijon 21079, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital d'Enfants, Dijon 21079, France.,Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Laurence Faivre
- Centre de Référence Anomalies du Développement et Syndromes Malformatifs, Hôpital d'Enfants, Dijon 21079, France.,Centre de Référence Déficiences Intellectuelles de Causes Rares, Hôpital d'Enfants, Dijon 21079, France.,Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Stéphane Bézieau
- Service de Génétique Médicale, CHU de Nantes, Nantes 44093, France
| | - Leon S Dure
- Department of Pediatrics and Neurology, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Daniel C Helbling
- Clinical Services Laboratory, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - David Bick
- Clinical Services Laboratory, HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
| | - Chengqi Xu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P. R. China
| | - Qiuyun Chen
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Department of Cardiovascular Medicine, Cleveland Clinic, Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam 3015, The Netherlands
| | - Antonio Vitobello
- Inserm UMR 1231 GAD team, Genetics of Developmental Disorders, Université de Bourgogne Franche-Comté, Dijon 21070, France
| | - Qing Kenneth Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Center for Human Genome Research, Cardio-X Institute, Huazhong University of Science and Technology, Wuhan, Hubei 430074, P. R. China.,Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Department of Cardiovascular Medicine, Cleveland Clinic, Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH 44195, USA.,Department of Genetics and Genome Science, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Loss-of-function BK channel mutation causes impaired mitochondria and progressive cerebellar ataxia. Proc Natl Acad Sci U S A 2020; 117:6023-6034. [PMID: 32132200 DOI: 10.1073/pnas.1920008117] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Despite a growing number of ion channel genes implicated in hereditary ataxia, it remains unclear how ion channel mutations lead to loss-of-function or death of cerebellar neurons. Mutations in the gene KCNMA1, encoding the α-subunit of the BK channel have emerged as responsible for a variety of neurological phenotypes. We describe a mutation (BKG354S) in KCNMA1, in a child with congenital and progressive cerebellar ataxia with cognitive impairment. The mutation in the BK channel selectivity filter dramatically reduced single-channel conductance and ion selectivity. The BKG354S channel trafficked normally to plasma, nuclear, and mitochondrial membranes, but caused reduced neurite outgrowth, cell viability, and mitochondrial content. Small interfering RNA (siRNA) knockdown of endogenous BK channels had similar effects. The BK activator, NS1619, rescued BKG354S cells but not siRNA-treated cells, by selectively blocking the mutant channels. When expressed in cerebellum via adenoassociated virus (AAV) viral transfection in mice, the mutant BKG354S channel, but not the BKWT channel, caused progressive impairment of several gait parameters consistent with cerebellar dysfunction from 40- to 80-d-old mice. Finally, treatment of the patient with chlorzoxazone, a BK/SK channel activator, partially improved motor function, but ataxia continued to progress. These studies indicate that a loss-of-function BK channel mutation causes ataxia and acts by reducing mitochondrial and subsequently cellular viability.
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36
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Moldenhauer HJ, Matychak KK, Meredith AL. Comparative gain-of-function effects of the KCNMA1-N999S mutation on human BK channel properties. J Neurophysiol 2019; 123:560-570. [PMID: 31851553 PMCID: PMC7052641 DOI: 10.1152/jn.00626.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
KCNMA1, encoding the voltage- and calcium-activated potassium channel, has a pivotal role in brain physiology. Mutations in KCNMA1 are associated with epilepsy and/or dyskinesia (PNKD3). Two KCNMA1 mutations correlated with these phenotypes, D434G and N999S, were previously identified as producing gain-of-function (GOF) effects on BK channel activity. Three new patients have been reported harboring N999S, one carrying a second mutation, R1128W, but the effects of these mutations have not yet been reported under physiological K+ conditions or compared to D434G. In this study, we characterize N999S, the novel N999S/R1128W double mutation, and D434G in a brain BK channel splice variant, comparing the effects on BK current properties under a physiological K+ gradient with action potential voltage commands. N999S, N999S/R1128W, and D434G cDNAs were expressed in HEK293T cells and characterized by patch-clamp electrophysiology. N999S BK currents were shifted to negative potentials, with faster activation and slower deactivation compared with wild type (WT) and D434G. The double mutation N999S/R1128W did not show any additional changes in current properties compared with N999S alone. The antiepileptic drug acetazolamide was assessed for its ability to directly modulate WT and N999S channels. Neither the WT nor N999S channels were sensitive to the antiepileptic drug acetazolamide, but both were sensitive to the inhibitor paxilline. We conclude that N999S is a strong GOF mutation that surpasses the D434G phenotype, without mitigation by R1128W. Acetazolamide has no direct modulatory action on either WT or N999S channels, indicating that its use may not be contraindicated in patients harboring GOF KCNMA1 mutations.NEW & NOTEWORTHY KCNMA1-linked channelopathy is a new neurological disorder characterized by mutations in the BK voltage- and calcium-activated potassium channel. The epilepsy- and dyskinesia-associated gain-of-function mutations N999S and D434G comprise the largest number of patients in the cohort. This study provides the first direct comparison between D434G and N999S BK channel properties as well as a novel double mutation, N999S/R1128W, from another patient, defining the functional effects during an action potential stimulus.
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Affiliation(s)
- Hans J Moldenhauer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Katia K Matychak
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland.,Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland
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37
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Customized multigene panels in epilepsy: the best things come in small packages. Neurogenetics 2019; 21:1-18. [PMID: 31834528 DOI: 10.1007/s10048-019-00598-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022]
Abstract
Over the past 10 years, the increasingly important role played by next-generation sequencing panels in the genetic diagnosis of epilepsy has led to a growing list of gene variants and a plethora of new scientific data. To date, however, there is still no consensus on what constitutes the "ideal panel design," or on the most rational criteria for selecting the best candidates for gene-panel analysis, even though both might optimize the cost-benefit ratio and the diagnostic efficiency of customized gene panels. Even though more and more laboratories are adopting whole-exome sequencing as a first-tier diagnostic approach, interpreting, "in silico," a set of epilepsy-related genes remains difficult. In the light of these considerations, we performed a systematic review of the targeted gene panels for epilepsy already reported in the available scientific literature, with a view to identifying the best criteria for selecting patients for gene-panel analysis, and the best way to design an "ideal," gold-standard panel that includes all genes with an established role in epilepsy pathogenesis, as well as those that might help to guide decisions regarding specific medical interventions and treatments. Our analyses suggest that the usefulness and diagnostic power of customized gene panels for epilepsy may be greatest when these panels are confined to rationally selected, relatively small, pools of genes, and applied in more carefully selected epilepsy patients (those with complex forms of epilepsy). A panel containing 64 genes, which includes the 45 genes harboring a significant number of pathogenic variants identified in previous literature, the 32 clinically actionable genes, and the 21 ILAE (International League Against Epilepsy) recommended genes, may represent an "ideal" core set likely able to provide the highest diagnostic efficiency and cost-effectiveness and facilitate gene prioritization when testing patients with whole-exome/whole-genome sequencing.
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38
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Plante AE, Lai MH, Lu J, Meredith AL. Effects of Single Nucleotide Polymorphisms in Human KCNMA1 on BK Current Properties. Front Mol Neurosci 2019; 12:285. [PMID: 31849601 PMCID: PMC6901604 DOI: 10.3389/fnmol.2019.00285] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 11/12/2019] [Indexed: 12/14/2022] Open
Abstract
BK Ca2+-activated K+ channels are important regulators of membrane excitability. Multiple regulatory mechanisms tailor BK current properties across tissues, such as alternative splicing, posttranslational modifications, and auxiliary subunits. Another potential mechanism for modulating BK channel activity is genetic variation due to single nucleotide polymorphisms (SNPs). The gene encoding the human BK α subunit, KCNMA1, contains hundreds of SNPs. However, the variation in BK channel activity due to SNPs is not well studied. Here, we screened the effects of four SNPs (A138V, C495G, N599D, and R800W) on BK currents in HEK293T cells, selected based on predicted protein pathogenicity or disease linkage. We found that the SNPs C495G and R800W had the largest effects on BK currents, affecting the conductance–voltage relationship across multiple Ca2+ conditions in the context of two BK channel splice variants. In symmetrical K+, C495G shifted the V1/2 to more hyperpolarized potentials (by −15 to −20 mV) and accelerated activation, indicating C495G confers some gain-of-function properties. R800W shifted the V1/2 to more depolarized potentials (+15 to +35 mV) and slowed activation, conferring loss-of-function properties. Moreover, the C495G and R800W effects on current properties were found to persist with posttranslational modifications. In contrast, A138V and N599D had smaller and more variable effects on current properties. Neither application of alkaline phosphatase to patches, which results in increased BK channel activity attributed to channel dephosphorylation, nor bidirectional redox modulations completely abrogated SNP effects on BK currents. Lastly, in physiological K+, C495G increased the amplitude of action potential (AP)-evoked BK currents, while R800W had a more limited effect. However, the introduction of R800W in parallel with the epilepsy-linked mutation D434G (D434G/R800W) decreased the amplitude of AP-evoked BK currents compared with D434G alone. These results suggest that in a physiological context, C495G could increase BK activation, while the effects of the loss-of-function SNP R800W could oppose the gain-of-function effects of an epilepsy-linked mutation. Together, these results implicate naturally occurring human genetic variation as a potential modifier of BK channel activity across a variety of conditions.
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Affiliation(s)
- Amber E Plante
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Michael H Lai
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Jessica Lu
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Andrea L Meredith
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
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39
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Bailey CS, Moldenhauer HJ, Park SM, Keros S, Meredith AL. KCNMA1-linked channelopathy. J Gen Physiol 2019; 151:1173-1189. [PMID: 31427379 PMCID: PMC6785733 DOI: 10.1085/jgp.201912457] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 08/13/2019] [Indexed: 12/20/2022] Open
Abstract
Bailey et al. review a new neurological channelopathy associated with KCNMA1, encoding the BK voltage- and Ca2+-activated K+ channel. KCNMA1 encodes the pore-forming α subunit of the “Big K+” (BK) large conductance calcium and voltage-activated K+ channel. BK channels are widely distributed across tissues, including both excitable and nonexcitable cells. Expression levels are highest in brain and muscle, where BK channels are critical regulators of neuronal excitability and muscle contractility. A global deletion in mouse (KCNMA1−/−) is viable but exhibits pathophysiology in many organ systems. Yet despite the important roles in animal models, the consequences of dysfunctional BK channels in humans are not well characterized. Here, we summarize 16 rare KCNMA1 mutations identified in 37 patients dating back to 2005, with an array of clinically defined pathological phenotypes collectively referred to as “KCNMA1-linked channelopathy.” These mutations encompass gain-of-function (GOF) and loss-of-function (LOF) alterations in BK channel activity, as well as several variants of unknown significance (VUS). Human KCNMA1 mutations are primarily associated with neurological conditions, including seizures, movement disorders, developmental delay, and intellectual disability. Due to the recent identification of additional patients, the spectrum of symptoms associated with KCNMA1 mutations has expanded but remains primarily defined by brain and muscle dysfunction. Emerging evidence suggests the functional BK channel alterations produced by different KCNMA1 alleles may associate with semi-distinct patient symptoms, such as paroxysmal nonkinesigenic dyskinesia (PNKD) with GOF and ataxia with LOF. However, due to the de novo origins for the majority of KCNMA1 mutations identified to date and the phenotypic variability exhibited by patients, additional evidence is required to establish causality in most cases. The symptomatic picture developing from patients with KCNMA1-linked channelopathy highlights the importance of better understanding the roles BK channels play in regulating cell excitability. Establishing causality between KCNMA1-linked BK channel dysfunction and specific patient symptoms may reveal new treatment approaches with the potential to increase therapeutic efficacy over current standard regimens.
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Affiliation(s)
- Cole S Bailey
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Hans J Moldenhauer
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Su Mi Park
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
| | - Sotirios Keros
- Department of Pediatrics, University of South Dakota Sanford School of Medicine, Sioux Falls, SD
| | - Andrea L Meredith
- Dept. of Physiology, University of Maryland School of Medicine, Baltimore, MD
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An Epilepsy-Associated KCNT1 Mutation Enhances Excitability of Human iPSC-Derived Neurons by Increasing Slack K Na Currents. J Neurosci 2019; 39:7438-7449. [PMID: 31350261 DOI: 10.1523/jneurosci.1628-18.2019] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/08/2019] [Accepted: 07/17/2019] [Indexed: 12/26/2022] Open
Abstract
Mutations in the KCNT1 (Slack, KNa1.1) sodium-activated potassium channel produce severe epileptic encephalopathies. Expression in heterologous systems has shown that the disease-causing mutations give rise to channels that have increased current amplitude. It is not known, however, whether such gain of function occurs in human neurons, nor whether such increased KNa current is expected to suppress or increase the excitability of cortical neurons. Using genetically engineered human induced pluripotent stem cell (iPSC)-derived neurons, we have now found that sodium-dependent potassium currents are increased several-fold in neurons bearing a homozygous P924L mutation. In current-clamp recordings, the increased KNa current in neurons with the P924L mutation acts to shorten the duration of action potentials and to increase the amplitude of the afterhyperpolarization that follows each action potential. Strikingly, the number of action potentials that were evoked by depolarizing currents as well as maximal firing rates were increased in neurons expressing the mutant channel. In networks of spontaneously active neurons, the mean firing rate, the occurrence of rapid bursts of action potentials, and the intensity of firing during the burst were all increased in neurons with the P924L Slack mutation. The feasibility of an increased KNa current to increase firing rates independent of any compensatory changes was validated by numerical simulations. Our findings indicate that gain-of-function in Slack KNa channels causes hyperexcitability in both isolated neurons and in neural networks and occurs by a cell-autonomous mechanism that does not require network interactions.SIGNIFICANCE STATEMENT KCNT1 mutations lead to severe epileptic encephalopathies for which there are no effective treatments. This study is the first demonstration that a KCNT1 mutation increases the Slack current in neurons. It also provides the first explanation for how this increased potassium current induces hyperexcitability, which could be the underlining factor causing seizures.
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UBC9 regulates cardiac sodium channel Na v1.5 ubiquitination, degradation and sodium current density. J Mol Cell Cardiol 2019; 129:79-91. [PMID: 30772377 DOI: 10.1016/j.yjmcc.2019.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 12/29/2022]
Abstract
Voltage-gated sodium channel Nav1.5 is critical for generation and conduction of cardiac action potentials. Mutations and expression level changes of Nav1.5 are associated with cardiac arrhythmias and sudden death. The ubiquitin (Ub) conjugation machinery utilizes three enzyme activities, E1, E2, and E3, to regulate protein degradation. Previous studies from us and others showed that Nedd4-2 acts as an E3 ubiquitin-protein ligase involved in ubiquitination and degradation of Nav1.5, however, more key regulators remain to be identified. In this study, we show that UBC9, a SUMO-conjugating enzyme, regulates ubiquitination and degradation of Nav1.5. Overexpression of UBC9 significantly decreased Nav1.5 expression and reduced sodium current densities, whereas knockdown of UBC9 expression significantly enhanced Nav1.5 expression and increased sodium current densities, in both HEK293 cells and primary neonatal cardiomyocytes. Overexpression of UBC9 increased ubiquitination of Nav1.5, and proteasome inhibitor MG132 blocked the effect of UBC9 overexpression on Nav1.5 degradation. Co-immunoprecipitation showed that UBC9 interacts with Nedd4-2. UBC9 with mutation C93S, which suppresses SUMO-conjugating activity of UBC9, was as active as wild type UBC9 in regulating Nav1.5 levels, suggesting that UBC9 regulates Nav1.5 expression levels in a SUMOylation-independent manner. Our findings thus identify a key structural element of the ubiquitin-conjugation machinery for Nav1.5 and provide important insights into the regulatory mechanism for ubiquitination and turnover of Nav1.5.
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42
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Kshatri AS, Gonzalez-Hernandez A, Giraldez T. Physiological Roles and Therapeutic Potential of Ca 2+ Activated Potassium Channels in the Nervous System. Front Mol Neurosci 2018; 11:258. [PMID: 30104956 PMCID: PMC6077210 DOI: 10.3389/fnmol.2018.00258] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/06/2018] [Indexed: 12/21/2022] Open
Abstract
Within the potassium ion channel family, calcium activated potassium (KCa) channels are unique in their ability to couple intracellular Ca2+ signals to membrane potential variations. KCa channels are diversely distributed throughout the central nervous system and play fundamental roles ranging from regulating neuronal excitability to controlling neurotransmitter release. The physiological versatility of KCa channels is enhanced by alternative splicing and co-assembly with auxiliary subunits, leading to fundamental differences in distribution, subunit composition and pharmacological profiles. Thus, understanding specific KCa channels’ mechanisms in neuronal function is challenging. Based on their single channel conductance, KCa channels are divided into three subtypes: small (SK, 4–14 pS), intermediate (IK, 32–39 pS) and big potassium (BK, 200–300 pS) channels. This review describes the biophysical characteristics of these KCa channels, as well as their physiological roles and pathological implications. In addition, we also discuss the current pharmacological strategies and challenges to target KCa channels for the treatment of various neurological and psychiatric disorders.
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Affiliation(s)
- Aravind S Kshatri
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Alberto Gonzalez-Hernandez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Teresa Giraldez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
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Abstract
Mutations in the cereblon (CRBN) gene cause human intellectual disability, one of the most common cognitive disorders. However, the molecular mechanisms of CRBN-related intellectual disability remain poorly understood. We investigated the role of CRBN in synaptic function and animal behavior using male mouse and Drosophila models. Crbn knock-out (KO) mice showed normal brain and spine morphology as well as intact synaptic plasticity; however, they also exhibited decreases in synaptic transmission and presynaptic release probability exclusively in excitatory synapses. Presynaptic function was impaired not only by loss of CRBN expression, but also by expression of pathogenic CRBN mutants (human R419X mutant and Drosophila G552X mutant). We found that the BK channel blockers paxilline and iberiotoxin reversed this decrease in presynaptic release probability in Crbn KO mice. In addition, paxilline treatment also restored normal cognitive behavior in Crbn KO mice. These results strongly suggest that increased BK channel activity is the pathological mechanism of intellectual disability in CRBN mutations.SIGNIFICANCE STATEMENTCereblon (CRBN), a well known target of the immunomodulatory drug thalidomide, was originally identified as a gene that causes human intellectual disability when mutated. However, the molecular mechanisms of CRBN-related intellectual disability remain poorly understood. Based on the idea that synaptic abnormalities are the most common factor in cognitive dysfunction, we monitored the synaptic structure and function of Crbn knock-out (KO) animals to identify the molecular mechanisms of intellectual disability. Here, we found that Crbn KO animals showed cognitive deficits caused by enhanced BK channel activity and reduced presynaptic glutamate release. Our findings suggest a physiological pathomechanism of the intellectual disability-related gene CRBN and will contribute to the development of therapeutic strategies for CRBN-related intellectual disability.
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