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Rusina E, Simonti M, Duprat F, Cestèle S, Mantegazza M. Voltage-gated sodium channels in genetic epilepsy: up and down of excitability. J Neurochem 2023. [PMID: 37654020 DOI: 10.1111/jnc.15947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 08/11/2023] [Accepted: 08/13/2023] [Indexed: 09/02/2023]
Abstract
The past two decades have witnessed a wide range of studies investigating genetic variants of voltage-gated sodium (NaV ) channels, which are involved in a broad spectrum of diseases, including several types of epilepsy. We have reviewed here phenotypes and pathological mechanisms of genetic epilepsies caused by variants in NaV α and β subunits, as well as of some relevant interacting proteins (FGF12/FHF1, PRRT2, and Ankyrin-G). Notably, variants of all these genes can induce either gain- or loss-of-function of NaV leading to either neuronal hyperexcitability or hypoexcitability. We present the results of functional studies obtained with different experimental models, highlighting that they should be interpreted considering the features of the experimental system used. These systems are models, but they have allowed us to better understand pathophysiological issues, ameliorate diagnostics, orientate genetic counseling, and select/develop therapies within a precision medicine framework. These studies have also allowed us to gain insights into the physiological roles of different NaV channels and of the cells that express them. Overall, our review shows the progress that has been made, but also the need for further studies on aspects that have not yet been clarified. Finally, we conclude by highlighting some significant themes of general interest that can be gleaned from the results of the work of the last two decades.
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Affiliation(s)
- Evgeniia Rusina
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Martina Simonti
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Fabrice Duprat
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
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2
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Bryson A, Petrou S. SCN1A channelopathies: Navigating from genotype to neural circuit dysfunction. Front Neurol 2023; 14:1173460. [PMID: 37139072 PMCID: PMC10149698 DOI: 10.3389/fneur.2023.1173460] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/28/2023] [Indexed: 05/05/2023] Open
Abstract
The SCN1A gene is strongly associated with epilepsy and plays a central role for supporting cortical excitation-inhibition balance through the expression of NaV1.1 within inhibitory interneurons. The phenotype of SCN1A disorders has been conceptualized as driven primarily by impaired interneuron function that predisposes to disinhibition and cortical hyperexcitability. However, recent studies have identified SCN1A gain-of-function variants associated with epilepsy, and the presence of cellular and synaptic changes in mouse models that point toward homeostatic adaptations and complex network remodeling. These findings highlight the need to understand microcircuit-scale dysfunction in SCN1A disorders to contextualize genetic and cellular disease mechanisms. Targeting the restoration of microcircuit properties may be a fruitful strategy for the development of novel therapies.
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Affiliation(s)
- Alexander Bryson
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
- *Correspondence: Alexander Bryson,
| | - Steven Petrou
- Ion Channels and Disease Group, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
- Praxis Precision Medicines, Inc., Cambridge, MA, United States
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3
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Brunklaus A, Feng T, Brünger T, Perez-Palma E, Heyne H, Matthews E, Semsarian C, Symonds JD, Zuberi SM, Lal D, Schorge S. Gene variant effects across sodium channelopathies predict function and guide precision therapy. Brain 2022; 145:4275-4286. [PMID: 35037686 PMCID: PMC9897196 DOI: 10.1093/brain/awac006] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 11/27/2021] [Accepted: 12/10/2021] [Indexed: 11/14/2022] Open
Abstract
Pathogenic variants in the voltage-gated sodium channel gene family lead to early onset epilepsies, neurodevelopmental disorders, skeletal muscle channelopathies, peripheral neuropathies and cardiac arrhythmias. Disease-associated variants have diverse functional effects ranging from complete loss-of-function to marked gain-of-function. Therapeutic strategy is likely to depend on functional effect. Experimental studies offer important insights into channel function but are resource intensive and only performed in a minority of cases. Given the evolutionarily conserved nature of the sodium channel genes, we investigated whether similarities in biophysical properties between different voltage-gated sodium channels can predict function and inform precision treatment across sodium channelopathies. We performed a systematic literature search identifying functionally assessed variants in any of the nine voltage-gated sodium channel genes until 28 April 2021. We included missense variants that had been electrophysiologically characterized in mammalian cells in whole-cell patch-clamp recordings. We performed an alignment of linear protein sequences of all sodium channel genes and correlated variants by their overall functional effect on biophysical properties. Of 951 identified records, 437 sodium channel-variants met our inclusion criteria and were reviewed for functional properties. Of these, 141 variants were epilepsy-associated (SCN1/2/3/8A), 79 had a neuromuscular phenotype (SCN4/9/10/11A), 149 were associated with a cardiac phenotype (SCN5/10A) and 68 (16%) were considered benign. We detected 38 missense variant pairs with an identical disease-associated variant in a different sodium channel gene. Thirty-five out of 38 of those pairs resulted in similar functional consequences, indicating up to 92% biophysical agreement between corresponding sodium channel variants (odds ratio = 11.3; 95% confidence interval = 2.8 to 66.9; P < 0.001). Pathogenic missense variants were clustered in specific functional domains, whereas population variants were significantly more frequent across non-conserved domains (odds ratio = 18.6; 95% confidence interval = 10.9-34.4; P < 0.001). Pore-loop regions were frequently associated with loss-of-function variants, whereas inactivation sites were associated with gain-of-function (odds ratio = 42.1, 95% confidence interval = 14.5-122.4; P < 0.001), whilst variants occurring in voltage-sensing regions comprised a range of gain- and loss-of-function effects. Our findings suggest that biophysical characterisation of variants in one SCN-gene can predict channel function across different SCN-genes where experimental data are not available. The collected data represent the first gain- versus loss-of-function topological map of SCN proteins indicating shared patterns of biophysical effects aiding variant analysis and guiding precision therapy. We integrated our findings into a free online webtool to facilitate functional sodium channel gene variant interpretation (http://SCN-viewer.broadinstitute.org).
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Affiliation(s)
- Andreas Brunklaus
- Correspondence to: Dr Andreas Brunklaus, MD Fraser of Allander Neurosciences Unit Office Block, Ground Floor, Zone 2 Royal Hospital for Children 1345 Govan Road Glasgow G51 4TF, UK E-mail:
| | | | | | - Eduardo Perez-Palma
- Centro de Genética y Genómica, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Henrike Heyne
- Genomic and Personalized Medicine, Digital Health Center, Hasso Plattner Institute, Potsdam, Germany
- Hasso Plattner Institute, Mount Sinai School of Medicine, New York, NY, USA
- Institute for Molecular Medicine Finland: FIMM, Helsinki, Finland
| | - Emma Matthews
- Atkinson Morley Neuromuscular Centre, St George’s University Hospitals NHS Foundation Trust, London, UK
- Molecular and Clinical Sciences Research Institute, St George’s University of London, London, UK
| | - Christopher Semsarian
- Agnes Ginges Centre for Molecular Cardiology at Centenary Institute, The University of Sydney, Sydney, Australia
- Sydney Medical School Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Department of Cardiology, Royal Prince Alfred Hospital, Sydney, Australia
| | - Joseph D Symonds
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
- Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Sameer M Zuberi
- The Paediatric Neurosciences Research Group, Royal Hospital for Children, Glasgow, UK
- Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK
| | - Dennis Lal
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, USA
- Stanley Center for Psychiatric Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Stephanie Schorge
- Correspondence may also be addressed to: Professor Stephanie Schorge, PhD Department of Neuroscience Physiology and Pharmacology UCL, London WC1E 6BT, UK E-mail:
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4
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Fang Z, Xie L, Li X, Gui J, Yang X, Han Z, Luo H, Huang D, Chen H, Cheng L, Jiang L. Severe epilepsy phenotype with SCN1A missense variants located outside the sodium channel core region: Relationship between functional results and clinical phenotype. Seizure 2022; 101:109-116. [PMID: 35944423 DOI: 10.1016/j.seizure.2022.07.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/17/2022] [Accepted: 07/29/2022] [Indexed: 11/28/2022] Open
Abstract
PURPOSE Most SCN1A missense variants located outside the sodium channel core region show a mild phenotype. However, there are exceptions, because of which it is challenging to determine the correlation between genotype and phenotype. In this study, we aimed to determine whether functional study could be used to determine disease severity in cases with such variants, and elucidate possible genotype-phenotype relationships. METHODS Forty-seven patients with SCN1A missense variants were recruited, and one with a Dravet syndrome phenotype with an SCN1A missense variant (c.3811T>C/ p.W1271R) located outside the core region was screened with electrophysiological tests. We also reviewed functional SCN1A studies on patients with inconsistent phenotypes and genotypes, and studied the relationship between electrophysiological measurements and clinical phenotype. RESULTS Patch clamp experiments showed that the W1271R variant caused significantly reduced sodium current, decreased channel voltage sensitivity, loss of channel availability, and prolonged recovery time from inactivation compared with wild type (WT), which ultimately caused a change in loss of function (LOF). Twelve cases of severe SCN1A-related epilepsy with missense variants located outside the channel core region were also included from the functional studies. Nine patients with missense SCN1A variants showed complete (3/9) or partial (6/9) physiological LOF. Two missense SCN1A variants caused physiological gain-and-loss of function (G-LOF), and one caused decreased excitability (DE). CONCLUSIONS Not all missense variants located outside the core region cause a mild phenotype. Although current functional studies in heterologous expression systems do not accurately reflect disease severity caused by SCN1A missense variants, they could be an effective model for generation of data to study the initial effects of SCN1A missense variants.
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Affiliation(s)
- Zhixu Fang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Lingling Xie
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Xue Li
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Jianxiong Gui
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Xiaoyue Yang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Ziyao Han
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Hanyu Luo
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Dishu Huang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Hengsheng Chen
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Li Cheng
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China
| | - Li Jiang
- Department of Neurology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, No. 136, Zhongshan Er Road, Yuzhong District, Chongqing 400014, China.
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5
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Abstract
Drug-resistant epilepsy is associated with poor health outcomes and increased economic burden. In the last three decades, various new antiseizure medications have been developed, but the proportion of people with drug-resistant epilepsy remains relatively unchanged. Developing strategies to address drug-resistant epilepsy is essential. Here, we define drug-resistant epilepsy and emphasize its relationship to the conceptualization of epilepsy as a symptom complex, delineate clinical risk factors, and characterize mechanisms based on current knowledge. We address the importance of ruling out pseudoresistance and consider the impact of nonadherence on determining whether an individual has drug-resistant epilepsy. We then review the principles of epilepsy drug therapy and briefly touch upon newly approved and experimental antiseizure medications.
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6
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Zhou Z, Li JV, Martinac B, Cox CD. Loss-of-Function Piezo1 Mutations Display Altered Stability Driven by Ubiquitination and Proteasomal Degradation. Front Pharmacol 2021; 12:766416. [PMID: 34867393 PMCID: PMC8640252 DOI: 10.3389/fphar.2021.766416] [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: 08/29/2021] [Accepted: 11/03/2021] [Indexed: 01/02/2023] Open
Abstract
Missense mutations in the gene that encodes for the mechanically-gated ion channel Piezo1 have been linked to a number of diseases. Gain-of-function variants are linked to a hereditary anaemia and loss-of-function variants have been linked to generalized lymphatic dysplasia and bicuspid aortic valve. Two previously characterized mutations, S217L and G2029R, both exhibit reduced plasma membrane trafficking. Here we show that both mutations also display reduced stability and higher turnover rates than wild-type Piezo1 channels. This occurs through increased ubiquitination and subsequent proteasomal degradation. Congruent with this, proteasome inhibition using N-acetyl-l-leucyl-l-leucyl-l-norleucinal (ALLN) reduced the degradation of both mutant proteins. While ALLN treatment could not rescue the function of S217L we show via multiple complementary methodologies that proteasome inhibition via ALLN treatment can not only prevent G2029R turnover but increase the membrane localized pool of this variant and the functional Piezo1 mechanosensitive currents. This data in combination with a precision medicine approach provides a new potential therapeutic avenue for the treatment of Piezo1 mediated channelopathies.
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Affiliation(s)
- Zijing Zhou
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, NSW, Australia
| | - Jinyuan Vero Li
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, NSW, Australia
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.,St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Charles D Cox
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.,St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
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7
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Wu X, Hong L. Calmodulin Interactions with Voltage-Gated Sodium Channels. Int J Mol Sci 2021; 22:ijms22189798. [PMID: 34575961 PMCID: PMC8472079 DOI: 10.3390/ijms22189798] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 02/06/2023] Open
Abstract
Calmodulin (CaM) is a small protein that acts as a ubiquitous signal transducer and regulates neuronal plasticity, muscle contraction, and immune response. It interacts with ion channels and plays regulatory roles in cellular electrophysiology. CaM modulates the voltage-gated sodium channel gating process, alters sodium current density, and regulates sodium channel protein trafficking and expression. Many mutations in the CaM-binding IQ domain give rise to diseases including epilepsy, autism, and arrhythmias by interfering with CaM interaction with the channel. In the present review, we discuss CaM interactions with the voltage-gated sodium channel and modulators involved in CaM regulation, as well as summarize CaM-binding IQ domain mutations associated with human diseases in the voltage-gated sodium channel family.
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8
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Comparative structural analysis of human Na v1.1 and Na v1.5 reveals mutational hotspots for sodium channelopathies. Proc Natl Acad Sci U S A 2021; 118:2100066118. [PMID: 33712547 DOI: 10.1073/pnas.2100066118] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Among the nine subtypes of human voltage-gated sodium (Nav) channels, the brain and cardiac isoforms, Nav1.1 and Nav1.5, each carry more than 400 missense mutations respectively associated with epilepsy and cardiac disorders. High-resolution structures are required for structure-function relationship dissection of the disease variants. We report the cryo-EM structures of the full-length human Nav1.1-β4 complex at 3.3 Å resolution here and the Nav1.5-E1784K variant in the accompanying paper. Up to 341 and 261 disease-related missense mutations in Nav1.1 and Nav1.5, respectively, are resolved. Comparative structural analysis reveals several clusters of disease mutations that are common to both Nav1.1 and Nav1.5. Among these, the majority of mutations on the extracellular loops above the pore domain and the supporting segments for the selectivity filter may impair structural integrity, while those on the pore domain and the voltage-sensing domains mostly interfere with electromechanical coupling and fast inactivation. Our systematic structural delineation of these mutations provides important insight into their pathogenic mechanism, which will facilitate the development of precise therapeutic interventions against various sodium channelopathies.
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9
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Montnach J, De Waard S, Nicolas S, Burel S, Osorio N, Zoukimian C, Mantegazza M, Boukaiba R, Béroud R, Partiseti M, Delmas P, Marionneau C, De Waard M. Fluorescent- and tagged-protoxin II peptides: potent markers of the Na v 1.7 channel pain target. Br J Pharmacol 2021; 178:2632-2650. [PMID: 33742442 DOI: 10.1111/bph.15453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/26/2021] [Accepted: 02/09/2021] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE Protoxin II (ProTx II) is a high affinity gating modifier that is thought to selectively block the Nav 1.7 voltage-dependent Na+ channel, a major therapeutic target for the control of pain. We aimed at producing ProTx II analogues entitled with novel functionalities for cell distribution studies and biochemical characterization of its Nav channel targets. EXPERIMENTAL APPROACH We took advantage of the high affinity properties of the peptide, combined to its slow off rate, to design a number of new tagged analogues useful for imaging and biochemistry purposes. We used high-throughput automated patch-clamp to identify the analogues best matching the native properties of ProTx II and validated them on various Nav -expressing cells in pull-down and cell distribution studies. KEY RESULTS Two of the produced ProTx II analogues, Biot-ProTx II and ATTO488-ProTx II, best emulate the pharmacological properties of unlabelled ProTx II, whereas other analogues remain high affinity blockers of Nav 1.7. The biotinylated version of ProTx II efficiently works for the pull-down of several Nav isoforms tested in a concentration-dependent manner, whereas the fluorescent ATTO488-ProTx II specifically labels the Nav 1.7 channel over other Nav isoforms tested in various experimental conditions. CONCLUSIONS AND IMPLICATIONS The properties of these ProTx II analogues as tools for Nav channel purification and cell distribution studies pave the way for a better understanding of ProTx II channel receptors in pain and their pathophysiological implications in sensory neuronal processing. The new fluorescent ProTx II should also be useful in the design of new drug screening strategies.
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Affiliation(s)
- Jérôme Montnach
- LabEx "Ion Channels, Science & Therapeutics", l'institut du thorax, INSERM, CNRS, UNIV NANTES, Nantes, France
| | - Stephan De Waard
- LabEx "Ion Channels, Science & Therapeutics", l'institut du thorax, INSERM, CNRS, UNIV NANTES, Nantes, France
| | - Sébastien Nicolas
- LabEx "Ion Channels, Science & Therapeutics", l'institut du thorax, INSERM, CNRS, UNIV NANTES, Nantes, France
| | - Sophie Burel
- LabEx "Ion Channels, Science & Therapeutics", l'institut du thorax, INSERM, CNRS, UNIV NANTES, Nantes, France
| | - Nancy Osorio
- Laboratory of Cognitive Neuroscience, UMR 7291, CNRS, Aix-Marseille University, Marseille, France
| | | | - Massimo Mantegazza
- Université Cote d'Azur, CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis, France
| | - Rachid Boukaiba
- Sanofi R&D, Integrated Drug Discovery - High Content Biology, Vitry-sur-Seine, France
| | | | - Michel Partiseti
- Sanofi R&D, Integrated Drug Discovery - High Content Biology, Vitry-sur-Seine, France
| | - Patrick Delmas
- Laboratory of Cognitive Neuroscience, UMR 7291, CNRS, Aix-Marseille University, Marseille, France
| | - Céline Marionneau
- LabEx "Ion Channels, Science & Therapeutics", l'institut du thorax, INSERM, CNRS, UNIV NANTES, Nantes, France
| | - Michel De Waard
- LabEx "Ion Channels, Science & Therapeutics", l'institut du thorax, INSERM, CNRS, UNIV NANTES, Nantes, France.,Smartox Biotechnology, Saint-Egrève, France
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10
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Interneuron Dysfunction in a New Mouse Model of SCN1A GEFS. eNeuro 2021; 8:ENEURO.0394-20.2021. [PMID: 33658306 PMCID: PMC8174035 DOI: 10.1523/eneuro.0394-20.2021] [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: 09/14/2020] [Revised: 02/15/2021] [Accepted: 02/19/2021] [Indexed: 11/21/2022] Open
Abstract
Advances in genome sequencing have identified over 1300 mutations in the SCN1A sodium channel gene that result in genetic epilepsies. However, it still remains unclear how most individual mutations within SCN1A result in seizures. A previous study has shown that the K1270T (KT) mutation, linked to genetic epilepsy with febrile seizure plus (GEFS+) in humans, causes heat-induced seizure activity associated with a temperature-dependent decrease in GABAergic neuron excitability in a Drosophila knock-in model. To examine the behavioral and cellular effects of this mutation in mammals, we introduced the equivalent KT mutation into the mouse (Mus musculus) Scn1a (Scn1aKT) gene using CRISPR/Cas9 and generated mutant lines in two widely used genetic backgrounds: C57BL/6NJ and 129X1/SvJ. In both backgrounds, mice homozygous for the KT mutation had spontaneous seizures and died by postnatal day (P)23. There was no difference in mortality of heterozygous KT mice compared with wild-type littermates up to six months old. Heterozygous mutants exhibited heat-induced seizures at ∼42°C, a temperature that did not induce seizures in wild-type littermates. In acute hippocampal slices at permissive temperatures, current-clamp recordings revealed a significantly depolarized shift in action potential threshold and reduced action potential amplitude in parvalbumin (PV)-expressing inhibitory CA1 interneurons in Scn1aKT/+ mice. There was no change in the firing properties of excitatory CA1 pyramidal neurons. These results suggest that a constitutive decrease in inhibitory interneuron excitability contributes to the seizure phenotype in the mouse model.
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11
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Mantegazza M, Cestèle S, Catterall WA. Sodium channelopathies of skeletal muscle and brain. Physiol Rev 2021; 101:1633-1689. [PMID: 33769100 DOI: 10.1152/physrev.00025.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated sodium channels initiate action potentials in nerve, skeletal muscle, and other electrically excitable cells. Mutations in them cause a wide range of diseases. These channelopathy mutations affect every aspect of sodium channel function, including voltage sensing, voltage-dependent activation, ion conductance, fast and slow inactivation, and both biosynthesis and assembly. Mutations that cause different forms of periodic paralysis in skeletal muscle were discovered first and have provided a template for understanding structure, function, and pathophysiology at the molecular level. More recent work has revealed multiple sodium channelopathies in the brain. Here we review the well-characterized genetics and pathophysiology of the periodic paralyses of skeletal muscle and then use this information as a foundation for advancing our understanding of mutations in the structurally homologous α-subunits of brain sodium channels that cause epilepsy, migraine, autism, and related comorbidities. We include studies based on molecular and structural biology, cell biology and physiology, pharmacology, and mouse genetics. Our review reveals unexpected connections among these different types of sodium channelopathies.
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Affiliation(s)
- Massimo Mantegazza
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France.,INSERM, Valbonne-Sophia Antipolis, France
| | - Sandrine Cestèle
- Université Cote d'Azur, Valbonne-Sophia Antipolis, France.,CNRS UMR7275, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne-Sophia Antipolis, France
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12
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Juvale IIA, Che Has AT. Possible interplay between the theories of pharmacoresistant epilepsy. Eur J Neurosci 2020; 53:1998-2026. [PMID: 33306252 DOI: 10.1111/ejn.15079] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 11/22/2020] [Accepted: 12/04/2020] [Indexed: 02/06/2023]
Abstract
Epilepsy is one of the oldest known neurological disorders and is characterized by recurrent seizure activity. It has a high incidence rate, affecting a broad demographic in both developed and developing countries. Comorbid conditions are frequent in patients with epilepsy and have detrimental effects on their quality of life. Current management options for epilepsy include the use of anti-epileptic drugs, surgery, or a ketogenic diet. However, more than 30% of patients diagnosed with epilepsy exhibit drug resistance to anti-epileptic drugs. Further, surgery and ketogenic diets do little to alleviate the symptoms of patients with pharmacoresistant epilepsy. Thus, there is an urgent need to understand the underlying mechanisms of pharmacoresistant epilepsy to design newer and more effective anti-epileptic drugs. Several theories of pharmacoresistant epilepsy have been suggested over the years, the most common being the gene variant hypothesis, network hypothesis, multidrug transporter hypothesis, and target hypothesis. In our review, we discuss the main theories of pharmacoresistant epilepsy and highlight a possible interconnection between their mechanisms that could lead to the development of novel therapies for pharmacoresistant epilepsy.
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Affiliation(s)
- Iman Imtiyaz Ahmed Juvale
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia
| | - Ahmad Tarmizi Che Has
- Department of Neurosciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia
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13
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Solé L, Tamkun MM. Trafficking mechanisms underlying Na v channel subcellular localization in neurons. Channels (Austin) 2020; 14:1-17. [PMID: 31841065 PMCID: PMC7039628 DOI: 10.1080/19336950.2019.1700082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 11/13/2019] [Indexed: 01/06/2023] Open
Abstract
Voltage gated sodium channels (Nav) play a crucial role in action potential initiation and propagation. Although the discovery of Nav channels dates back more than 65 years, and great advances in understanding their localization, biophysical properties, and links to disease have been made, there are still many questions to be answered regarding the cellular and molecular mechanisms involved in Nav channel trafficking, localization and regulation. This review summarizes the different trafficking mechanisms underlying the polarized Nav channel localization in neurons, with an emphasis on the axon initial segment (AIS), as well as discussing the latest advances regarding how neurons regulate their excitability by modifying AIS length and location. The importance of Nav channel localization is emphasized by the relationship between mutations, impaired trafficking and disease. While this review focuses on Nav1.6, other Nav isoforms are also discussed.
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Affiliation(s)
- Laura Solé
- Molecular, Cellular and Integrative Neurosciences Graduate Program, Colorado State University, Fort Collins, CO, USA
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Michael M. Tamkun
- Molecular, Cellular and Integrative Neurosciences Graduate Program, Colorado State University, Fort Collins, CO, USA
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
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14
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Kluckova D, Kolnikova M, Lacinova L, Jurkovicova-Tarabova B, Foltan T, Demko V, Kadasi L, Ficek A, Soltysova A. A Study among the Genotype, Functional Alternations, and Phenotype of 9 SCN1A Mutations in Epilepsy Patients. Sci Rep 2020; 10:10288. [PMID: 32581296 PMCID: PMC7314844 DOI: 10.1038/s41598-020-67215-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/26/2020] [Indexed: 12/14/2022] Open
Abstract
Mutations in the voltage-gated sodium channel Nav1.1 (SCN1A) are linked to various epileptic phenotypes with different severities, however, the consequences of newly identified SCN1A variants on patient phenotype is uncertain so far. The functional impact of nine SCN1A variants, including five novel variants identified in this study, was studied using whole-cell patch-clamp recordings measurement of mutant Nav1.1 channels expressed in HEK293T mammalian cells. E78X, W384X, E1587K, and R1596C channels failed to produce measurable sodium currents, indicating complete loss of channel function. E788K and M909K variants resulted in partial loss of function by exhibiting reduced current density, depolarizing shifts of the activation and hyperpolarizing shifts of the inactivation curves, and slower recovery from inactivation. Hyperpolarizing shifts of the activation and inactivation curves were observed in D249E channels along with slower recovery from inactivation. Slower recovery from inactivation was observed in E78D and T1934I with reduced current density in T1934I channels. Various functional effects were observed with the lack of sodium current being mainly associated with severe phenotypes and milder symptoms with less damaging channel alteration. In vitro functional analysis is thus fundamental for elucidation of the molecular mechanisms of epilepsy, to guide patients' treatment, and finally indicate misdiagnosis of SCN1A related epilepsies.
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Affiliation(s)
- Daniela Kluckova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia
| | - Miriam Kolnikova
- Department of Pediatric Neurology, Comenius University Medical School and National Institute of Children's Diseases, Limbova 1, Bratislava, 833 40, Slovakia
| | - Lubica Lacinova
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Dubravská cesta 9, Bratislava, 840 05, Slovakia
| | - Bohumila Jurkovicova-Tarabova
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Dubravská cesta 9, Bratislava, 840 05, Slovakia
| | - Tomas Foltan
- Department of Pediatric Neurology, Comenius University Medical School and National Institute of Children's Diseases, Limbova 1, Bratislava, 833 40, Slovakia
| | - Viktor Demko
- Department of Plant Physiology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia
| | - Ludevit Kadasi
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia.,Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05, Bratislava, Slovakia
| | - Andrej Ficek
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia
| | - Andrea Soltysova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, Bratislava, 842 15, Slovakia. .,Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05, Bratislava, Slovakia.
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15
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Mantegazza M, Broccoli V. SCN1A/Na V 1.1 channelopathies: Mechanisms in expression systems, animal models, and human iPSC models. Epilepsia 2020; 60 Suppl 3:S25-S38. [PMID: 31904127 DOI: 10.1111/epi.14700] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 03/04/2019] [Indexed: 12/20/2022]
Abstract
Pathogenic SCN1A/NaV 1.1 mutations cause well-defined epilepsies, including genetic epilepsy with febrile seizures plus (GEFS+) and the severe epileptic encephalopathy Dravet syndrome. In addition, they cause a severe form of migraine with aura, familial hemiplegic migraine. Moreover, SCN1A/NaV 1.1 variants have been inferred as risk factors in other types of epilepsy. We review here the advancements obtained studying pathologic mechanisms of SCN1A/NaV 1.1 mutations with experimental systems. We present results gained with in vitro expression systems, gene-targeted animal models, and the induced pluripotent stem cell (iPSC) technology, highlighting advantages, limits, and pitfalls for each of these systems. Overall, the results obtained in the last two decades confirm that the initial pathologic mechanism of epileptogenic SCN1A/NaV 1.1 mutations is loss-of-function of NaV 1.1 leading to hypoexcitability of at least some types of γ-aminobutyric acid (GABA)ergic neurons (including cortical and hippocampal parvalbumin-positive and somatostatin-positive ones). Conversely, more limited results point to NaV 1.1 gain-of-function for familial hemiplegic migraine (FHM) mutations. Behind these relatively simple pathologic mechanisms, an unexpected complexity has been observed, in part generated by technical issues in experimental studies and in part related to intrinsically complex pathophysiologic responses and remodeling, which yet remain to be fully disentangled.
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Affiliation(s)
- Massimo Mantegazza
- University Cote d'Azur (UCA), CNRS UMR7275, INSERM, Institute of Molecular and Cellular Pharmacology (IPMC), Valbonne-Sophia Antipolis, France
| | - Vania Broccoli
- San Raffaele Scientific Institute, Milan, Italy.,Institute of Neuroscience, National Research Council (CNR), Milan, Italy
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16
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Pan Y, Cummins TR. Distinct functional alterations in SCN8A epilepsy mutant channels. J Physiol 2020; 598:381-401. [PMID: 31715021 PMCID: PMC7216308 DOI: 10.1113/jp278952] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/12/2019] [Indexed: 01/12/2023] Open
Abstract
KEY POINTS Mutations in the SCN8A gene cause early infantile epileptic encephalopathy. We characterize a new epilepsy-related SCN8A mutation, R850Q, in the human SCN8A channel and present gain-of-function properties of the mutant channel. Systematic comparison of R850Q with three other SCN8A epilepsy mutations, T761I, R1617Q and R1872Q, identifies one common dysfunction in resurgent current, although these mutations alter distinct properties of the channel. Computational simulations in two different neuron models predict an increased excitability of neurons carrying these mutations, which explains the over-excitation that underlies seizure activities in patients. These data provide further insight into the mechanism of SCN8A-related epilepsy and reveal subtle but potentially important distinction of functional characterization performed in the human vs. rodent channels. ABSTRACT SCN8A is a novel causal gene for early infantile epileptic encephalopathy. It is well accepted that gain-of-function mutations in SCN8A underlie the disorder, although the remarkable heterogeneity of its clinical presentation and poor treatment response demand a better understanding of the disease mechanisms. Here, we characterize a new epilepsy-related SCN8A mutation, R850Q, in human Nav1.6. We show that it is a gain-of-function mutation, with a hyperpolarizing shift in voltage dependence of activation, a two-fold increase of persistent current and a slowed decay of resurgent current. We systematically compare its biophysics with three other SCN8A epilepsy mutations, T767I, R1617Q and R1872Q, in the human Nav1.6 channel. Although all of these mutations are gain-of-function, the mutations affect different aspects of channel properties. One commonality that we discovered is an alteration of resurgent current kinetics, although the mechanisms by which resurgent currents are augmented remain unclear for all of the mutations. Computational simulations predict an increased excitability of neurons carrying these mutations with differential enhancement by open channel blockade.
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Affiliation(s)
- Yanling Pan
- Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, IN, USA
| | - Theodore R Cummins
- Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, IN, USA
- Department of Biology, School of Science, IUPUI, IN, USA
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17
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Brunklaus A, Schorge S, Smith AD, Ghanty I, Stewart K, Gardiner S, Du J, Pérez‐Palma E, Symonds JD, Collier AC, Lal D, Zuberi SM. SCN1A
variants from bench to bedside—improved clinical prediction from functional characterization. Hum Mutat 2019; 41:363-374. [PMID: 31782251 DOI: 10.1002/humu.23943] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 10/10/2019] [Accepted: 10/31/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Andreas Brunklaus
- The Paediatric Neurosciences Research GroupRoyal Hospital for ChildrenGlasgow UK
- School of MedicineUniversity of GlasgowGlasgow UK
| | - Stephanie Schorge
- Department of Clinical and Experimental Epilepsy, Institute of NeurologyUniversity College LondonLondon UK
- School of PharmacyUniversity College LondonLondon UK
| | - Alexander D. Smith
- Faculty of Pharmaceutical SciencesThe University of British ColumbiaVancouver British Columbia Canada
| | - Ismael Ghanty
- The Paediatric Neurosciences Research GroupRoyal Hospital for ChildrenGlasgow UK
- School of MedicineUniversity of GlasgowGlasgow UK
| | - Kirsty Stewart
- West of Scotland Genetic Services, Level 2B, Laboratory MedicineQueen Elizabeth University HospitalGlasgow UK
| | - Sarah Gardiner
- West of Scotland Genetic Services, Level 2B, Laboratory MedicineQueen Elizabeth University HospitalGlasgow UK
| | - Juanjiangmeng Du
- Cologne Center for Genomics, University Hospital CologneUniversity of CologneCologne Germany
| | - Eduardo Pérez‐Palma
- Cologne Center for Genomics, University Hospital CologneUniversity of CologneCologne Germany
| | - Joseph D. Symonds
- The Paediatric Neurosciences Research GroupRoyal Hospital for ChildrenGlasgow UK
- School of MedicineUniversity of GlasgowGlasgow UK
| | - Abby C. Collier
- Faculty of Pharmaceutical SciencesThe University of British ColumbiaVancouver British Columbia Canada
| | - Dennis Lal
- Cologne Center for Genomics, University Hospital CologneUniversity of CologneCologne Germany
- Stanley Center for Psychiatric ResearchBroad Institute of MIT and HarvardCambridge Massachusetts
- Analytic and Translational Genetics UnitMassachusetts General HospitalBoston Massachusetts
- Epilepsy Center, Neurological InstituteCleveland ClinicCleveland Ohio
- Genomic Medicine InstituteLerner Research Institute Cleveland ClinicCleveland Ohio
| | - Sameer M. Zuberi
- The Paediatric Neurosciences Research GroupRoyal Hospital for ChildrenGlasgow UK
- School of MedicineUniversity of GlasgowGlasgow UK
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18
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Marinko J, Huang H, Penn WD, Capra JA, Schlebach JP, Sanders CR. Folding and Misfolding of Human Membrane Proteins in Health and Disease: From Single Molecules to Cellular Proteostasis. Chem Rev 2019; 119:5537-5606. [PMID: 30608666 PMCID: PMC6506414 DOI: 10.1021/acs.chemrev.8b00532] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Indexed: 12/13/2022]
Abstract
Advances over the past 25 years have revealed much about how the structural properties of membranes and associated proteins are linked to the thermodynamics and kinetics of membrane protein (MP) folding. At the same time biochemical progress has outlined how cellular proteostasis networks mediate MP folding and manage misfolding in the cell. When combined with results from genomic sequencing, these studies have established paradigms for how MP folding and misfolding are linked to the molecular etiologies of a variety of diseases. This emerging framework has paved the way for the development of a new class of small molecule "pharmacological chaperones" that bind to and stabilize misfolded MP variants, some of which are now in clinical use. In this review, we comprehensively outline current perspectives on the folding and misfolding of integral MPs as well as the mechanisms of cellular MP quality control. Based on these perspectives, we highlight new opportunities for innovations that bridge our molecular understanding of the energetics of MP folding with the nuanced complexity of biological systems. Given the many linkages between MP misfolding and human disease, we also examine some of the exciting opportunities to leverage these advances to address emerging challenges in the development of therapeutics and precision medicine.
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Affiliation(s)
- Justin
T. Marinko
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Hui Huang
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Wesley D. Penn
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - John A. Capra
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37245, United States
| | - Jonathan P. Schlebach
- Department
of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Charles R. Sanders
- Department
of Biochemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
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19
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Nissenkorn A, Almog Y, Adler I, Safrin M, Brusel M, Marom M, Bercovich S, Yakubovich D, Tzadok M, Ben-Zeev B, Rubinstein M. In vivo, in vitro and in silico correlations of four de novo SCN1A missense mutations. PLoS One 2019; 14:e0211901. [PMID: 30735520 PMCID: PMC6368302 DOI: 10.1371/journal.pone.0211901] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 01/22/2019] [Indexed: 12/31/2022] Open
Abstract
Mutations in the SCN1A gene, which encodes for the voltage-gated sodium channel NaV1.1, cause Dravet syndrome, a severe developmental and epileptic encephalopathy. Genetic testing of this gene is recommended early in life. However, predicting the outcome of de novo missense SCN1A mutations is difficult, since milder epileptic syndromes may also be associated. In this study, we correlated clinical severity with functional in vitro electrophysiological testing of channel activity and bioinformatics prediction of damaging mutational effects. Three patients, bearing the mutations p.Gly177Ala, p.Ser259Arg and p.Glu1923Arg, showed frequent intractable seizures that had started early in life, with cognitive and behavioral deterioration, consistent with classical Dravet phenotypes. These mutations failed to produce measurable sodium currents in a mammalian expression system, indicating complete loss of channel function. A fourth patient, who harbored the mutation p.Met1267Ile, though presenting with seizures early in life, showed lower seizure burden and higher cognitive function, matching borderland Dravet phenotypes. In correlation with this, functional analysis demonstrated the presence of sodium currents, but with partial loss of function. In contrast, six bioinformatics tools for predicting mutational pathogenicity suggested similar impact for all mutations. Likewise, homology modeling of the secondary and tertiary structures failed to reveal misfolding. In conclusion, functional studies using patch clamp are suggested as a prognostic tool, whereby detectable currents imply milder phenotypes and absence of currents indicate an unfavorable prognosis. Future development of automated patch clamp systems will facilitate the inclusion of such functional testing as part of personalized patient diagnostic schemes.
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Affiliation(s)
- Andreea Nissenkorn
- Service for Rare Disorders, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Tel HaShomer, Israel
- Pediatric Neurology Unit, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Tel HaShomer, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yael Almog
- Goldschleger Eye Research Institute, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Inbar Adler
- Goldschleger Eye Research Institute, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Mary Safrin
- Goldschleger Eye Research Institute, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Marina Brusel
- Goldschleger Eye Research Institute, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Milit Marom
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Shayel Bercovich
- The Arrow Project, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Tel HaShomer, Israel
| | - Daniel Yakubovich
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Neonatal Intensive Care, Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Tel HaShomer, Israel
| | - Michal Tzadok
- Pediatric Neurology Unit, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Tel HaShomer, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Bruria Ben-Zeev
- Pediatric Neurology Unit, The Edmond and Lily Safra Children’s Hospital, Chaim Sheba Medical Center, Tel HaShomer, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Moran Rubinstein
- Goldschleger Eye Research Institute, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
- The Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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20
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Familial episodic limb pain in kindreds with novel Nav1.9 mutations. PLoS One 2018; 13:e0208516. [PMID: 30557356 PMCID: PMC6296736 DOI: 10.1371/journal.pone.0208516] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 11/19/2018] [Indexed: 12/18/2022] Open
Abstract
We previously performed genetic analysis in six unrelated families with infantile limb pain episodes, characterized by cold-induced deterioration and mitigation in adolescence, and reported two new mutations p.R222H/S in SCN11A responsible for these episodes. As no term described this syndrome (familial episodic pain: FEP) in Japanese, we named it as”小児四肢疼痛発作症”. In the current study, we recruited an additional 42 new unrelated Japanese FEP families, between March 2016 and March 2018, and identified a total of 11 mutations in SCN11A: p.R222H in seven families, and p.R225C, p.F814C, p.F1146S, or p.V1184A, in independent families. A founder mutation, SCN11A p.R222H was confirmed to be frequently observed in patients with FEP in the Tohoku region of Japan. We also identified two novel missense variants of SCN11A, p.F814C and p.F1146S. To evaluate the effects of these latter two mutations, we generated knock-in mouse models harboring p.F802C (F802C) and p.F1125S (F1125S), orthologues of the human p.F814C and p.F1146S, respectively. We then performed electrophysiological investigations using dorsal root ganglion neurons dissected from the 6–8 week-old mice. Dissected neurons of F802C and F1125S mice showed increased resting membrane potentials and firing frequency of the action potentials (APs) by high input–current stimulus compared with WT mice. Furthermore, the firing probability of evoked APs increased in low stimulus input in F1125S mice, whereas several AP parameters and current threshold did not differ significantly between either of the mutations and WT mice. These results suggest a higher level of excitability in the F802C or F1125S mice than in WT, and indicate that these novel mutations are gain of function mutations. It can be expected that a considerable number of potential patients with FEP may be the result of gain of function SCN11A mutations.
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21
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Loss-of-function of Nav1.8/D1639N linked to human pain can be rescued by lidocaine. Pflugers Arch 2018; 470:1787-1801. [PMID: 30099632 DOI: 10.1007/s00424-018-2189-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 07/25/2018] [Accepted: 07/27/2018] [Indexed: 01/31/2023]
Abstract
Mutations in voltage-gated sodium channels are associated with altered pain perception in humans. Most of these mutations studied to date present with a direct and intuitive link between the altered electrophysiological function of the channel and the phenotype of the patient. In this study, we characterize a variant of Nav1.8, D1639N, which has been previously identified in a patient suffering from the chronic pain syndrome "small fiber neuropathy". Using a heterologous expression system and patch-clamp analysis, we show that Nav1.8/D1639N reduces current density without altering biophysical gating properties of Nav1.8. Therefore, the D1639N variant causes a loss-of-function of the Nav1.8 sodium channel in a patient suffering from chronic pain. Using immunocytochemistry and biochemical approaches, we show that Nav1.8/D1639N impairs trafficking of the channel to the cell membrane. Neither co-expression of β1 or β3 subunit, nor overnight incubation at 27 °C rescued current density of the D1639N variant. On the other hand, overnight incubation with lidocaine fully restored current density of Nav1.8/D1639N most likely by overcoming the trafficking defect, whereas phenytoin failed to do so. Since lidocaine rescues the loss-of-function of Nav1.8/D1639N, it may offer a future therapeutic option for the patient carrying this variant. These results demonstrate that the D1639N variant, identified in a patient suffering from chronic pain, causes loss-of-function of the channel due to impaired cell surface trafficking and that this trafficking defect can be rescued by lidocaine.
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22
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Baroni D, Picco C, Moran O. A mutation of SCN1B associated with GEFS+ causes functional and maturation defects of the voltage-dependent sodium channel. Hum Mutat 2018; 39:1402-1415. [PMID: 29992740 DOI: 10.1002/humu.23589] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/25/2018] [Accepted: 07/03/2018] [Indexed: 12/19/2022]
Abstract
Voltage-dependent sodium channels are responsible of the rising phase of the action potential in excitable cells. These integral membrane proteins are composed of a pore-forming α-subunit, and one or more auxiliary β subunits. Mutation p.Asp25Asn (D25N; c.73G > A) of the β1 subunit, coded by the gene SCN1B, has been reported in a patient with generalized epilepsy with febrile seizure plus type 1 (GEFS+). In human embryonic kidney 293 (HEK) cells, the heterologous coexpression of D25N-β1 subunit with Nav1.2, Nav1.4, and Nav1.5 α subunits, representative of brain, skeletal muscle, and heart voltage gated sodium channels, determines a reduced sodium channel functional expression and a negative shift of the activation and inactivation steady state curves. The D25N mutation of the β1 subunit causes a maturation (glycosylation) defect of the protein, leading to a reduced targeting to the plasma membrane. Also the β1-dependent gating properties of the sodium channels are abolished by the mutation, suggesting that D25N is no more able to interact with the α subunit. Our work underscores the role played by the β1 subunit, highlighting how a defective interaction between the sodium channel constituents could lead to a disabling pathological condition, and opens the possibility to design a mutation-specific GEFS+ treatment based on protein maturation.
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23
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Dhifallah S, Lancaster E, Merrill S, Leroudier N, Mantegazza M, Cestèle S. Gain of Function for the SCN1A/hNa v1.1-L1670W Mutation Responsible for Familial Hemiplegic Migraine. Front Mol Neurosci 2018; 11:232. [PMID: 30038559 PMCID: PMC6046441 DOI: 10.3389/fnmol.2018.00232] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/12/2018] [Indexed: 12/21/2022] Open
Abstract
The SCN1A gene encodes for the voltage-dependent Nav1.1 Na+ channel, an isoform mainly expressed in GABAergic neurons that is the target of hundreds of epileptogenic mutations. More recently, it has been shown that the SCN1A gene is also the target of mutations responsible for familial hemiplegic migraine (FHM-3), a rare autosomal dominant subtype of migraine with aura. Studies of these mutations indicate that they induce gain of function of the channel. Surprisingly, the mutation L1649Q responsible for pure FHM-3 showed a complete loss of function, but, when partially rescued it induced an overall gain of function because of modification of the gating properties of the mutant channel. Here, we report the characterization of the L1670W SCN1A mutation that has been previously identified in a Chinese family with pure FHM-3, and that we have identified also in a Caucasian American family with pure FHM-3. Notably, one patient in our family had severe neurological deterioration after brain radiation for cancer treatment. Functional analysis of L1670W reveals that the mutation is responsible for folding/trafficking defects and, when they are rescued by incubation at lower temperature or by expression in neurons, modifications of the gating properties lead to an overall gain of function. Therefore, L1670W is the second mutation responsible for FHM-3 with this pathophysiological mechanism, showing that it may be a recurrent mechanism for Nav1.1 hemiplegic migraine mutations.
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Affiliation(s)
- Sandra Dhifallah
- Université Côte d'Azur, CNRS UMR 7275, INSERM, IPMC, Valbonne, France
| | - Eric Lancaster
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States
| | - Shana Merrill
- Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States
| | | | | | - Sandrine Cestèle
- Université Côte d'Azur, CNRS UMR 7275, INSERM, IPMC, Valbonne, France
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Yang Y, Adi T, Effraim PR, Chen L, Dib‐Hajj SD, Waxman SG. Reverse pharmacogenomics: carbamazepine normalizes activation and attenuates thermal hyperexcitability of sensory neurons due to Na v 1.7 mutation I234T. Br J Pharmacol 2018; 175:2261-2271. [PMID: 28658526 PMCID: PMC5980548 DOI: 10.1111/bph.13935] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 04/17/2017] [Accepted: 06/05/2017] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE Pharmacotherapy for pain currently involves trial and error. A previous study on inherited erythromelalgia (a genetic model of neuropathic pain due to mutations in the sodium channel, Nav 1.7) used genomics, structural modelling and biophysical and pharmacological analyses to guide pharmacotherapy and showed that carbamazepine normalizes voltage dependence of activation of the Nav 1.7-S241T mutant channel, reducing pain in patients carrying this mutation. However, whether this approach is applicable to other Nav channel mutants is still unknown. EXPERIMENTAL APPROACH We used structural modelling, patch clamp and multi-electrode array (MEA) recording to assess the effects of carbamazepine on Nav 1.7-I234T mutant channels and on the firing of dorsal root ganglion (DRG) sensory neurons expressing these mutant channels. KEY RESULTS In a reverse engineering approach, structural modelling showed that the I234T mutation is located in atomic proximity to the carbamazepine-responsive S241T mutation and that activation of Nav 1.7-I234T mutant channels, from patients who are known to respond to carbamazepine, is partly normalized with a clinically relevant concentration (30 μM) of carbamazepine. There was significantly higher firing in intact sensory neurons expressing Nav 1.7-I234T channels, compared with neurons expressing the normal channels (Nav 1.7-WT). Pre-incubation with 30 μM carbamazepine also significantly reduced the firing of intact DRG sensory neurons expressing Nav 1.7-I234T channels. Although the expected use-dependent inhibition of Nav 1.7-WT channels by carbamazepine was confirmed, carbamazepine did not enhance use-dependent inhibition of Nav 1.7-I234T mutant channels. CONCLUSION AND IMPLICATIONS These results support the utility of a pharmacogenomic approach to treatment of pain in patients carrying sodium channel variants. LINKED ARTICLES This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Affiliation(s)
- Yang Yang
- Department of NeurologyYale University School of MedicineNew HavenCTUSA
- Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenCTUSA
- Rehabilitation Research CenterVA Connecticut Healthcare SystemWest HavenCTUSA
| | - Talia Adi
- Department of NeurologyYale University School of MedicineNew HavenCTUSA
- Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenCTUSA
- Rehabilitation Research CenterVA Connecticut Healthcare SystemWest HavenCTUSA
| | - Philip R Effraim
- Department of NeurologyYale University School of MedicineNew HavenCTUSA
- Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenCTUSA
- Rehabilitation Research CenterVA Connecticut Healthcare SystemWest HavenCTUSA
- Department of AnesthesiologyYale University School of MedicineNew HavenCTUSA
| | - Lubin Chen
- Department of NeurologyYale University School of MedicineNew HavenCTUSA
- Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenCTUSA
- Rehabilitation Research CenterVA Connecticut Healthcare SystemWest HavenCTUSA
| | - Sulayman D Dib‐Hajj
- Department of NeurologyYale University School of MedicineNew HavenCTUSA
- Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenCTUSA
- Rehabilitation Research CenterVA Connecticut Healthcare SystemWest HavenCTUSA
| | - Stephen G Waxman
- Department of NeurologyYale University School of MedicineNew HavenCTUSA
- Center for Neuroscience and Regeneration ResearchYale University School of MedicineNew HavenCTUSA
- Rehabilitation Research CenterVA Connecticut Healthcare SystemWest HavenCTUSA
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25
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Binini N, Sancini G, Villa C, Dal Magro R, Sansoni V, Rusconi R, Mantegazza M, Grioni D, Talpo F, Toselli M, Combi R. Identification of two mutations in cis in the SCN1A gene in a family showing genetic epilepsy with febrile seizures plus (GEFS+) and idiopathic generalized epilepsy (IGE). Brain Res 2017; 1677:26-32. [DOI: 10.1016/j.brainres.2017.09.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 11/29/2022]
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26
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Mantegazza M, Cestèle S. Pathophysiological mechanisms of migraine and epilepsy: Similarities and differences. Neurosci Lett 2017; 667:92-102. [PMID: 29129678 DOI: 10.1016/j.neulet.2017.11.025] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 11/08/2017] [Accepted: 11/08/2017] [Indexed: 01/03/2023]
Abstract
Migraine and epilepsy are episodic disorders with distinct features, but they have some clinical and pathophysiological overlaps. We review here clinical overlaps between seizures and migraine attacks, activities of neuronal networks observed during seizures and migraine attacks, and molecular and cellular mechanisms of migraine identified in genetic forms, focusing on genetic variants identified in hemiplegic migraine and their functional effects. Epilepsy and migraine can be generated by dysfunctions of the same neuronal networks, but these dysfunctions can be disease-specific, even if pathogenic mutations target the same protein. Studies of rare monogenic forms have allowed the identification of some molecular/cellular dysfunctions that provide a window on pathological mechanisms: we have begun to disclose the tip of the iceberg.
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Affiliation(s)
- Massimo Mantegazza
- Université Côte d'Azur (UCA), 660 route des Lucioles, 06560 Valbonne, Sophia Antipolis, France; Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 660 Route des Lucioles, 06560 Valbonne, Sophia Antipolis, France.
| | - Sandrine Cestèle
- Université Côte d'Azur (UCA), 660 route des Lucioles, 06560 Valbonne, Sophia Antipolis, France; Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 660 Route des Lucioles, 06560 Valbonne, Sophia Antipolis, France
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β1-C121W Is Down But Not Out: Epilepsy-Associated Scn1b-C121W Results in a Deleterious Gain-of-Function. J Neurosci 2017; 36:6213-24. [PMID: 27277800 DOI: 10.1523/jneurosci.0405-16.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/03/2016] [Indexed: 01/24/2023] Open
Abstract
UNLABELLED Voltage-gated sodium channel (VGSC) β subunits signal through multiple pathways on multiple time scales. In addition to modulating sodium and potassium currents, β subunits play nonconducting roles as cell adhesion molecules, which allow them to function in cell-cell communication, neuronal migration, neurite outgrowth, neuronal pathfinding, and axonal fasciculation. Mutations in SCN1B, encoding VGSC β1 and β1B, are associated with epilepsy. Autosomal-dominant SCN1B-C121W, the first epilepsy-associated VGSC mutation identified, results in genetic epilepsy with febrile seizures plus (GEFS+). This mutation has been shown to disrupt both the sodium-current-modulatory and cell-adhesive functions of β1 subunits expressed in heterologous systems. The goal of this study was to compare mice heterozygous for Scn1b-C121W (Scn1b(+/W)) with mice heterozygous for the Scn1b-null allele (Scn1b(+/-)) to determine whether the C121W mutation results in loss-of-function in vivo We found that Scn1b(+/W) mice were more susceptible than Scn1b(+/-) and Scn1b(+/+) mice to hyperthermia-induced convulsions, a model of pediatric febrile seizures. β1-C121W subunits are expressed at the neuronal cell surface in vivo However, despite this, β1-C121W polypeptides are incompletely glycosylated and do not associate with VGSC α subunits in the brain. β1-C121W subcellular localization is restricted to neuronal cell bodies and is not detected at axon initial segments in the cortex or cerebellum or at optic nerve nodes of Ranvier of Scn1b(W/W) mice. These data, together with our previous results showing that β1-C121W cannot participate in trans-homophilic cell adhesion, lead to the hypothesis that SCN1B-C121W confers a deleterious gain-of-function in human GEFS+ patients. SIGNIFICANCE STATEMENT The mechanisms underlying genetic epilepsy syndromes are poorly understood. Closing this gap in knowledge is essential to the development of new medicines to treat epilepsy. We have used mouse models to understand the mechanism of a mutation in the sodium channel gene SCN1B linked to genetic epilepsy with febrile seizures plus. We report that sodium channel β1 subunit proteins encoded by this mutant gene are expressed at the surface of neuronal cell bodies; however, they do not associate with the ion channel complex nor are they transported to areas of the axon that are critical for proper neuronal firing. We conclude that this disease-causing mutation is not simply a loss-of-function, but instead results in a deleterious gain-of-function in the brain.
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Terragni B, Scalmani P, Franceschetti S, Cestèle S, Mantegazza M. Post-translational dysfunctions in channelopathies of the nervous system. Neuropharmacology 2017; 132:31-42. [PMID: 28571716 DOI: 10.1016/j.neuropharm.2017.05.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/12/2017] [Accepted: 05/26/2017] [Indexed: 12/23/2022]
Abstract
Channelopathies comprise various diseases caused by defects of ion channels. Modifications of their biophysical properties are common and have been widely studied. However, ion channels are heterogeneous multi-molecular complexes that are extensively modulated and undergo a maturation process comprising numerous steps of structural modifications and intracellular trafficking. Perturbations of these processes can give rise to aberrant channels that cause pathologies. Here we review channelopathies of the nervous system associated with dysfunctions at the post-translational level (folding, trafficking, degradation, subcellular localization, interactions with associated proteins and structural post-translational modifications). We briefly outline the physiology of ion channels' maturation and discuss examples of defective mechanisms, focusing in particular on voltage-gated sodium channels, which are implicated in numerous neurological disorders. We also shortly introduce possible strategies to develop therapeutic approaches that target these processes. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Benedetta Terragni
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Paolo Scalmani
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Silvana Franceschetti
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Sandrine Cestèle
- Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 06560, Valbonne-Sophia Antipolis, France; University Côte d'Azur (UCA), 06560, Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 06560, Valbonne-Sophia Antipolis, France; University Côte d'Azur (UCA), 06560, Valbonne-Sophia Antipolis, France.
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29
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Warner TA, Liu Z, Macdonald RL, Kang JQ. Heat induced temperature dysregulation and seizures in Dravet Syndrome/GEFS+ Gabrg2 +/Q390X mice. Epilepsy Res 2017; 134:1-8. [PMID: 28505490 DOI: 10.1016/j.eplepsyres.2017.04.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 04/13/2017] [Accepted: 04/25/2017] [Indexed: 12/15/2022]
Abstract
It has been established that febrile seizures and its extended syndromes like generalized epilepsy with febrile seizures (FS) plus (GEFS+) and Dravet syndrome have been associated with mutations especially in SCN1A and GABRG2 genes. In patients, the onset of FS is likely due to the combined effect of temperature and inflammation in genetically vulnerable individuals because fever is often associated with infection. Much effort has been spent to understand the mechanisms underlying fever induction of seizures. In addition to the role of cytokines in FS, previous studies in Scn1a+/- knockout mice, a model of Dravet syndrome, indicated that temperature elevation alone could result in seizure generation, and the effect of elevated temperature inducing seizures was age-dependent. Here, we report the thermal effect in a different mouse model of Dravet syndrome, the Gabrg2+/Q390X knockin mouse. We demonstrated age-dependent dysregulated temperature control and that temperature elevation produced myoclonic jerks, generalized tonic clonic seizures (GTCSs) and heightened anxiety-like symptoms in Gabrg2+/Q390X mice. The study indicated that regardless of other inflammatory factors, brief heat alone increased brain excitability and induced multiple types of seizures in Gabrg2+/Q390X mice, suggesting that mutations like GABRG2(Q390X) may alter brain thermal regulation and precipitate seizures during temperature elevations.
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Affiliation(s)
- Timothy A Warner
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, United States
| | - Zhong Liu
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, United States
| | - Robert L Macdonald
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, United States; Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, United States; Vanderbilt Kennedy Center of Human Development, Vanderbilt University School of Medicine, Nashville, TN 37232, United States
| | - Jing-Qiong Kang
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, United States; Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, United States; Vanderbilt Kennedy Center of Human Development, Vanderbilt University School of Medicine, Nashville, TN 37232, United States.
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30
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Wolff M, Johannesen KM, Hedrich UBS, Masnada S, Rubboli G, Gardella E, Lesca G, Ville D, Milh M, Villard L, Afenjar A, Chantot-Bastaraud S, Mignot C, Lardennois C, Nava C, Schwarz N, Gérard M, Perrin L, Doummar D, Auvin S, Miranda MJ, Hempel M, Brilstra E, Knoers N, Verbeek N, van Kempen M, Braun KP, Mancini G, Biskup S, Hörtnagel K, Döcker M, Bast T, Loddenkemper T, Wong-Kisiel L, Baumeister FM, Fazeli W, Striano P, Dilena R, Fontana E, Zara F, Kurlemann G, Klepper J, Thoene JG, Arndt DH, Deconinck N, Schmitt-Mechelke T, Maier O, Muhle H, Wical B, Finetti C, Brückner R, Pietz J, Golla G, Jillella D, Linnet KM, Charles P, Moog U, Õiglane-Shlik E, Mantovani JF, Park K, Deprez M, Lederer D, Mary S, Scalais E, Selim L, Van Coster R, Lagae L, Nikanorova M, Hjalgrim H, Korenke GC, Trivisano M, Specchio N, Ceulemans B, Dorn T, Helbig KL, Hardies K, Stamberger H, de Jonghe P, Weckhuysen S, Lemke JR, Krägeloh-Mann I, Helbig I, Kluger G, Lerche H, Møller RS. Genetic and phenotypic heterogeneity suggest therapeutic implications in SCN2A-related disorders. Brain 2017; 140:1316-1336. [DOI: 10.1093/brain/awx054] [Citation(s) in RCA: 311] [Impact Index Per Article: 44.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 01/18/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Markus Wolff
- 1 Department of Pediatric Neurology and Developmental Medicine, University Children’s Hospital, Tübingen, Germany
| | - Katrine M. Johannesen
- 2 The Danish Epilepsy Centre, Dianalund, Denmark
- 3 Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Ulrike B. S. Hedrich
- 4 Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Silvia Masnada
- 5 Department of Brain and Behavior, University of Pavia, Italy
| | - Guido Rubboli
- 2 The Danish Epilepsy Centre, Dianalund, Denmark
- 6 University of Copenhagen, Copenhagen, Denmark
| | - Elena Gardella
- 2 The Danish Epilepsy Centre, Dianalund, Denmark
- 3 Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - Gaetan Lesca
- 7 Department of Genetics, Lyon University Hospital, Lyon, France
- 8 Claude Bernard Lyon I University, Lyon, France
- 9 Lyon Neuroscience Research Centre, CNRS UMRS5292, INSERM U1028, Lyon, France
| | - Dorothée Ville
- 10 Department of Pediatric Neurology and Reference Center for Rare Children Epilepsy and Tuberous Sclerosis, Hôpital Femme Mere Enfant, Centre Hospitalier Universitaire de Lyon, HCL, France
| | - Mathieu Milh
- 11 APHM Service de neurologie pédiatrique, Marseille, France
- 12 Aix Marseille Univ, Inserm, GMGF, UMR-S 910, Marseille, France
| | - Laurent Villard
- 12 Aix Marseille Univ, Inserm, GMGF, UMR-S 910, Marseille, France
| | - Alexandra Afenjar
- 13 AP-HP, Unité de Gènètique Clinique, Hôpital Armand Trousseau, Groupe Hospitalier Universitaire de l’Est Parisien, Paris, France
| | - Sandra Chantot-Bastaraud
- 13 AP-HP, Unité de Gènètique Clinique, Hôpital Armand Trousseau, Groupe Hospitalier Universitaire de l’Est Parisien, Paris, France
| | - Cyril Mignot
- 14 AP-HP, Département de Génétique; Centre de Référence Défiences Intellectuelles de Causes Rares; Groupe de Recherche Clinique UPMC “Déficiences Intellectuelles et Autisme” GH Pitié-Salpêtrère, Paris, France
| | - Caroline Lardennois
- 15 Service de Pediatrie neonatale et Réanimation - Neuropediatrie, 76000 Rouen, France
| | - Caroline Nava
- 16 Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, Inserm U 1127, CNRS UMR 7225, ICM, France
- 17 Department of Genetics, Pitié-Salpêtrière Hospital, AP-HP, F-75013 Paris, France
| | - Niklas Schwarz
- 4 Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | | | - Laurence Perrin
- 19 Department of Genetics, Robert Debré Hospital, AP-HP, Paris, France
| | - Diane Doummar
- 20 AP-HP, Service de Neuropédiatrie, Hôpital Trousseau, Paris, France
| | - Stéphane Auvin
- 21 Université Paris Diderot, Sorbonne Paris Cité, INSERM UMR1141, Paris, France
- 22 AP-HP, Hôpital Robert Debré, Service de Neurologie Pédiatrique, Paris, France
| | - Maria J. Miranda
- 23 Department of Pediatrics, Herlev University Hospital, Herlev, Denmark
| | - Maja Hempel
- 24 Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Eva Brilstra
- 25 Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Nine Knoers
- 25 Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Nienke Verbeek
- 25 Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Marjan van Kempen
- 25 Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Kees P. Braun
- 26 Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| | - Grazia Mancini
- 27 Department of Clinical Genetics, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Saskia Biskup
- 28 CeGaT - Center for Genomics and Transcriptomics, Tübingen, Germany
| | | | - Miriam Döcker
- 28 CeGaT - Center for Genomics and Transcriptomics, Tübingen, Germany
| | | | - Tobias Loddenkemper
- 30 Division of Epilepsy and Clinical Neurophysiology, Boston Children’s Hospital, Harvard Medical School, Boston MA, USA
| | - Lily Wong-Kisiel
- 31 Division of Child and Adolescent Neurology, Department of Neurology, Mayo Clinic, Rochester MN, USA
| | | | - Walid Fazeli
- 33 Pediatric Neurology, University Hospital Cologne, Germany
| | - Pasquale Striano
- 34 Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, and Maternal and Child Health, University of Genoa ‘G. Gaslini’ Institute, Genova, Italy
| | - Robertino Dilena
- 35 Servizio di Epilettologia e Neurofisiopatologia Pediatrica, UO Neurofisiopatologia, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milano, Italy
| | - Elena Fontana
- 36 Centro di Diagnosi e Cura delle Epilessie Infantili, Azienda Ospedaliera -Policlinico Gianbattista Rossi, Verona, Italy
| | - Federico Zara
- 37 Laboratory of Neurogenetics and Neuroscience, Department of Neuroscience, “G. Gaslini” Institute, Genova, Italy
| | - Gerhard Kurlemann
- 38 Department of Pediatric Neurology, University Children’s Hospital, Münster, Germany
| | - Joerg Klepper
- 39 Children’s Hospital, Klinikum Aschaffenburg, Germany
| | - Jess G. Thoene
- 40 University of Michigan, Pediatric Genetics, Ann Arbor, MI USA
| | - Daniel H. Arndt
- 41 Division of Pediatric Neurology and Epilepsy – Beaumont Children’s Hospital, William Beaumont Oakland University School of Medicine, Royal Oak, Michigan, USA
| | - Nicolas Deconinck
- 42 Department of Neurology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Thomas Schmitt-Mechelke
- 43 Children’s Hospital Lucerne, Luzerner Kantonsspital, Kinderspital Luzern, CH-6000 Luzern 16, Switzerland
| | - Oliver Maier
- 44 Department of child neurology, Children’s Hospital, St. Gallen, Switzerland
| | - Hiltrud Muhle
- 45 Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian-Albrechts University, Kiel, Germany
| | - Beverly Wical
- 46 Gillette Children’s Specialty Healthcare, Saint Paul, MN, USA
| | - Claudio Finetti
- 47 Klinik für Kinder- und Jugendmedizin, Elisabeth-Krankenhaus, Essen, Germany
| | | | - Joachim Pietz
- 49 Pediatric Practice University Medical Center for Children and Adolescents, Angelika Lautenschläger Children’s Hospital, Heidelberg, Germany
| | - Günther Golla
- 50 Klinik für Kinder- und Jugendmedizin, Klinikum Lippe GmbH, Detmold, Germany
| | - Dinesh Jillella
- 51 Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children’s Hospital, Boston, MA, USA
| | - Karen M. Linnet
- 52 Department of Pediatrics, Aarhus University hospital, Aarhus, Denmark
| | - Perrine Charles
- 53 Department of Genetics and Cytogenetics, Assistance Publique-Hôpitaux de Paris, Groupe Hospitalier Pitié-Salpêtrière Charles-Foix, Paris, France
| | - Ute Moog
- 54 Institute of Genetics, University Hospital, Heidelberg, Germany
| | - Eve Õiglane-Shlik
- 55 Children’s Clinic, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - John F. Mantovani
- 56 Department of Pediatrics and Mercy Kids Autism Center, Mercy Children’s Hospital, St. Louis, Missouri, USA
| | - Kristen Park
- 57 Department of Pediatrics and Neurology, Children’s Hospital Colorado, University of Colorado School of Medicine, Aurora, CO, USA
| | - Marie Deprez
- 58 Centre de Génétique Humaine, Institut de Pathologie et Génétique, Gosselies, Belgium
| | - Damien Lederer
- 58 Centre de Génétique Humaine, Institut de Pathologie et Génétique, Gosselies, Belgium
| | - Sandrine Mary
- 58 Centre de Génétique Humaine, Institut de Pathologie et Génétique, Gosselies, Belgium
| | - Emmanuel Scalais
- 59 Pediatric Neurology Unit, Pediatric Department, Centre Hospitalier de Luxembourg, Luxembourg
| | - Laila Selim
- 60 Department of Pediatrics, Pediatric Neurology and Neurometabolic Unit, Cairo University Children Hospital, Cairo, Egypt
| | - Rudy Van Coster
- 61 Department of Pediatrics, Division of Pediatric Neurology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Lieven Lagae
- 62 Department of Development and Regeneration, Section Pediatric Neurology, University Hospital KU Leuven, Leuven, Belgium
| | | | - Helle Hjalgrim
- 2 The Danish Epilepsy Centre, Dianalund, Denmark
- 3 Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
| | - G. Christoph Korenke
- 63 Zentrum für Kinder- und Jugendmedizin (Elisabeth Kinderkrankenhaus), Klinik für Neuropädiatrie u. Angeborene, Stoffwechselerkrankungen, Oldenburg, Germany
| | - Marina Trivisano
- 64 Neurology Unit, Department of Neuroscience, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Nicola Specchio
- 64 Neurology Unit, Department of Neuroscience, Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
| | - Berten Ceulemans
- 65 Paediatric Neurology University Hospital and University of Antwerp, Wilrijkstraat 10, 2650 Edegem, Belgium
| | - Thomas Dorn
- 66 Swiss Epilepsy Center, Zurich, Switzerland
| | - Katherine L. Helbig
- 67 Division of Clinical Genomics, Ambry Genetics, Aliso Viejo, California, USA
| | - Katia Hardies
- 68 Neurogenetics Group, Center for Molecular Neurology, VIB, Antwerp, Belgium
- 69 Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
| | - Hannah Stamberger
- 68 Neurogenetics Group, Center for Molecular Neurology, VIB, Antwerp, Belgium
- 69 Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
- 70 Division of Neurology, University Hospital Antwerp (UZA), Antwerp, Belgium
| | - Peter de Jonghe
- 68 Neurogenetics Group, Center for Molecular Neurology, VIB, Antwerp, Belgium
- 69 Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
- 70 Division of Neurology, University Hospital Antwerp (UZA), Antwerp, Belgium
| | - Sarah Weckhuysen
- 68 Neurogenetics Group, Center for Molecular Neurology, VIB, Antwerp, Belgium
- 69 Laboratory of Neurogenetics, Institute Born-Bunge, University of Antwerp, Antwerp, Belgium
- 70 Division of Neurology, University Hospital Antwerp (UZA), Antwerp, Belgium
| | - Johannes R. Lemke
- 71 Institute of Human Genetics, University of Leipzig Hospitals and Clinics, Leipzig, Germany
| | - Ingeborg Krägeloh-Mann
- 1 Department of Pediatric Neurology and Developmental Medicine, University Children’s Hospital, Tübingen, Germany
| | - Ingo Helbig
- 45 Department of Neuropediatrics, University Medical Center Schleswig-Holstein, Christian-Albrechts University, Kiel, Germany
- 72 Division of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, USA
| | - Gerhard Kluger
- 73 Neuropediatric Clinic and Clinic for Neurorehabilitation, Epilepsy Center for Children and Adolescents, Schoen Klinik, Vogtareuth, Germany
- 74 PMU Salzburg, Austria
| | - Holger Lerche
- 4 Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Rikke S Møller
- 2 The Danish Epilepsy Centre, Dianalund, Denmark
- 3 Institute for Regional Health Services, University of Southern Denmark, Odense, Denmark
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Lamar T, Vanoye CG, Calhoun J, Wong JC, Dutton SBB, Jorge BS, Velinov M, Escayg A, Kearney JA. SCN3A deficiency associated with increased seizure susceptibility. Neurobiol Dis 2017; 102:38-48. [PMID: 28235671 DOI: 10.1016/j.nbd.2017.02.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 01/24/2017] [Accepted: 02/20/2017] [Indexed: 11/25/2022] Open
Abstract
Mutations in voltage-gated sodium channels expressed highly in the brain (SCN1A, SCN2A, SCN3A, and SCN8A) are responsible for an increasing number of epilepsy syndromes. In particular, mutations in the SCN3A gene, encoding the pore-forming Nav1.3 α subunit, have been identified in patients with focal epilepsy. Biophysical characterization of epilepsy-associated SCN3A variants suggests that both gain- and loss-of-function SCN3A mutations may lead to increased seizure susceptibility. In this report, we identified a novel SCN3A variant (L247P) by whole exome sequencing of a child with focal epilepsy, developmental delay, and autonomic nervous system dysfunction. Voltage clamp analysis showed no detectable sodium current in a heterologous expression system expressing the SCN3A-L247P variant. Furthermore, cell surface biotinylation demonstrated a reduction in the amount of SCN3A-L247P at the cell surface, suggesting the SCN3A-L247P variant is a trafficking-deficient mutant. To further explore the possible clinical consequences of reduced SCN3A activity, we investigated the effect of a hypomorphic Scn3a allele (Scn3aHyp) on seizure susceptibility and behavior using a gene trap mouse line. Heterozygous Scn3a mutant mice (Scn3a+/Hyp) did not exhibit spontaneous seizures nor were they susceptible to hyperthermia-induced seizures. However, they displayed increased susceptibility to electroconvulsive (6Hz) and chemiconvulsive (flurothyl and kainic acid) induced seizures. Scn3a+/Hyp mice also exhibited deficits in locomotor activity and motor learning. Taken together, these results provide evidence that loss-of-function of SCN3A caused by reduced protein expression or deficient trafficking to the plasma membrane may contribute to increased seizure susceptibility.
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Affiliation(s)
- Tyra Lamar
- Department of Human Genetics, Emory University, Atlanta, GA, USA
| | - Carlos G Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jeffrey Calhoun
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jennifer C Wong
- Department of Human Genetics, Emory University, Atlanta, GA, USA
| | | | - Benjamin S Jorge
- Neuroscience Program, Vanderbilt University, Nashville, TN 37232, USA
| | - Milen Velinov
- New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA; Albert Einstein College of Medicine, Bronx, NY, USA
| | - Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, GA, USA.
| | - Jennifer A Kearney
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Abstract
Voltage-gated sodium channels (VGSC) are critical determinants of cellular electrical activity through the control of initiation and propagation of action potential. To ensure this role, these proteins are not consistently delivered to the plasma membrane but undergo drastic quality controls throughout various adaptive processes such as biosynthesis, anterograde and retrograde trafficking, and membrane targeting. In pathological conditions, this quality control could lead to the retention of functional VGSC and is therefore the target of different pharmacological approaches. The present chapter gives an overview of the current understanding of the facets of VGSC life cycle in the context of both cardiac and neuronal cell types.
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Affiliation(s)
- A Mercier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - P Bois
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - A Chatelier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France.
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Patel RR, Barbosa C, Brustovetsky T, Brustovetsky N, Cummins TR. Aberrant epilepsy-associated mutant Nav1.6 sodium channel activity can be targeted with cannabidiol. Brain 2016; 139:2164-81. [PMID: 27267376 DOI: 10.1093/brain/aww129] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 04/15/2016] [Indexed: 11/12/2022] Open
Abstract
Mutations in brain isoforms of voltage-gated sodium channels have been identified in patients with distinct epileptic phenotypes. Clinically, these patients often do not respond well to classic anti-epileptics and many remain refractory to treatment. Exogenous as well as endogenous cannabinoids have been shown to target voltage-gated sodium channels and cannabidiol has recently received attention for its potential efficacy in the treatment of childhood epilepsies. In this study, we further investigated the ability of cannabinoids to modulate sodium currents from wild-type and epilepsy-associated mutant voltage-gated sodium channels. We first determined the biophysical consequences of epilepsy-associated missense mutations in both Nav1.1 (arginine 1648 to histidine and asparagine 1788 to lysine) and Nav1.6 (asparagine 1768 to aspartic acid and leucine 1331 to valine) by obtaining whole-cell patch clamp recordings in human embryonic kidney 293T cells with 200 μM Navβ4 peptide in the pipette solution to induce resurgent sodium currents. Resurgent sodium current is an atypical near threshold current predicted to increase neuronal excitability and has been implicated in multiple disorders of excitability. We found that both mutations in Nav1.6 dramatically increased resurgent currents while mutations in Nav1.1 did not. We then examined the effects of anandamide and cannabidiol on peak transient and resurgent currents from wild-type and mutant channels. Interestingly, we found that cannabidiol can preferentially target resurgent sodium currents over peak transient currents generated by wild-type Nav1.6 as well as the aberrant resurgent and persistent current generated by Nav1.6 mutant channels. To further validate our findings, we examined the effects of cannabidiol on endogenous sodium currents from striatal neurons, and similarly we found an inhibition of resurgent and persistent current by cannabidiol. Moreover, current clamp recordings show that cannabidiol reduces overall action potential firing of striatal neurons. These findings suggest that cannabidiol could be exerting its anticonvulsant effects, at least in part, through its actions on voltage-gated sodium channels, and resurgent current may be a promising therapeutic target for the treatment of epilepsy syndromes.
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Affiliation(s)
- Reesha R Patel
- 1 Program in Medical Neuroscience, Neuroscience Research Building, 320 West 15th St, Indianapolis, IN, 46202, USA 2 Paul and Carole Stark Neurosciences Research Institute, 320 West 15th St, Indianapolis, IN, 46202, USA
| | - Cindy Barbosa
- 3 Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Tatiana Brustovetsky
- 3 Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Nickolay Brustovetsky
- 1 Program in Medical Neuroscience, Neuroscience Research Building, 320 West 15th St, Indianapolis, IN, 46202, USA 2 Paul and Carole Stark Neurosciences Research Institute, 320 West 15th St, Indianapolis, IN, 46202, USA 3 Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
| | - Theodore R Cummins
- 1 Program in Medical Neuroscience, Neuroscience Research Building, 320 West 15th St, Indianapolis, IN, 46202, USA 2 Paul and Carole Stark Neurosciences Research Institute, 320 West 15th St, Indianapolis, IN, 46202, USA 3 Department of Pharmacology and Toxicology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN, 46202, USA
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Imbrici P, Liantonio A, Camerino GM, De Bellis M, Camerino C, Mele A, Giustino A, Pierno S, De Luca A, Tricarico D, Desaphy JF, Conte D. Therapeutic Approaches to Genetic Ion Channelopathies and Perspectives in Drug Discovery. Front Pharmacol 2016; 7:121. [PMID: 27242528 PMCID: PMC4861771 DOI: 10.3389/fphar.2016.00121] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 04/25/2016] [Indexed: 12/21/2022] Open
Abstract
In the human genome more than 400 genes encode ion channels, which are transmembrane proteins mediating ion fluxes across membranes. Being expressed in all cell types, they are involved in almost all physiological processes, including sense perception, neurotransmission, muscle contraction, secretion, immune response, cell proliferation, and differentiation. Due to the widespread tissue distribution of ion channels and their physiological functions, mutations in genes encoding ion channel subunits, or their interacting proteins, are responsible for inherited ion channelopathies. These diseases can range from common to very rare disorders and their severity can be mild, disabling, or life-threatening. In spite of this, ion channels are the primary target of only about 5% of the marketed drugs suggesting their potential in drug discovery. The current review summarizes the therapeutic management of the principal ion channelopathies of central and peripheral nervous system, heart, kidney, bone, skeletal muscle and pancreas, resulting from mutations in calcium, sodium, potassium, and chloride ion channels. For most channelopathies the therapy is mainly empirical and symptomatic, often limited by lack of efficacy and tolerability for a significant number of patients. Other channelopathies can exploit ion channel targeted drugs, such as marketed sodium channel blockers. Developing new and more specific therapeutic approaches is therefore required. To this aim, a major advancement in the pharmacotherapy of channelopathies has been the discovery that ion channel mutations lead to change in biophysics that can in turn specifically modify the sensitivity to drugs: this opens the way to a pharmacogenetics strategy, allowing the development of a personalized therapy with increased efficacy and reduced side effects. In addition, the identification of disease modifiers in ion channelopathies appears an alternative strategy to discover novel druggable targets.
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Affiliation(s)
- Paola Imbrici
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Antonella Liantonio
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Giulia M Camerino
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Michela De Bellis
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Claudia Camerino
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari "Aldo Moro" Bari, Italy
| | - Antonietta Mele
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Arcangela Giustino
- Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro" Bari, Italy
| | - Sabata Pierno
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Annamaria De Luca
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Domenico Tricarico
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
| | - Jean-Francois Desaphy
- Department of Biomedical Sciences and Human Oncology, University of Bari "Aldo Moro" Bari, Italy
| | - Diana Conte
- Department of Pharmacy - Drug Sciences, University of Bari "Aldo Moro" Bari, Italy
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Sottas V, Abriel H. Negative-dominance phenomenon with genetic variants of the cardiac sodium channel Nav1.5. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1791-8. [PMID: 26907222 DOI: 10.1016/j.bbamcr.2016.02.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 02/15/2016] [Accepted: 02/19/2016] [Indexed: 02/07/2023]
Abstract
During the past two decades, many pathological genetic variants in SCN5A, the gene encoding the pore-forming subunit of the cardiac (monomeric) sodium channel Na(v)1.5, have been described. Negative dominance is a classical genetic concept involving a "poison" mutant peptide that negatively interferes with the co-expressed wild-type protein, thus reducing its cellular function. This phenomenon has been described for genetic variants of multimeric K(+) channels, which mechanisms are well understood. Unexpectedly, several pathologic SCN5A variants that are linked to Brugada syndrome also demonstrate such a dominant-negative (DN) effect. The molecular determinants of these observations, however, are not yet elucidated. This review article summarizes recent findings that describe the mechanisms underlying the DN phenomenon of genetic variants of K(+), Ca(2+), Cl(-) and Na(+) channels, and in particular Brugada syndrome variants of Na(v)1.5. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.
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Affiliation(s)
- Valentin Sottas
- Department of Clinical Research, Ion Channel Research Group, University of Bern, Switzerland
| | - Hugues Abriel
- Department of Clinical Research, Ion Channel Research Group, University of Bern, Switzerland.
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36
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Benítez-King G, Valdés-Tovar M, Trueta C, Galván-Arrieta T, Argueta J, Alarcón S, Lora-Castellanos A, Solís-Chagoyán H. The microtubular cytoskeleton of olfactory neurons derived from patients with schizophrenia or with bipolar disorder: Implications for biomarker characterization, neuronal physiology and pharmacological screening. Mol Cell Neurosci 2016; 73:84-95. [PMID: 26837043 DOI: 10.1016/j.mcn.2016.01.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 01/26/2016] [Accepted: 01/29/2016] [Indexed: 01/29/2023] Open
Abstract
Schizophrenia (SZ) and Bipolar Disorder (BD) are highly inheritable chronic mental disorders with a worldwide prevalence of around 1%. Despite that many efforts had been made to characterize biomarkers in order to allow for biological testing for their diagnoses, these disorders are currently detected and classified only by clinical appraisal based on the Diagnostic and Statistical Manual of Mental Disorders. Olfactory neuroepithelium-derived neuronal precursors have been recently proposed as a model for biomarker characterization. Because of their peripheral localization, they are amenable to collection and suitable for being cultured and propagated in vitro. Olfactory neuroepithelial cells can be obtained by a non-invasive brush-exfoliation technique from neuropsychiatric patients and healthy subjects. Neuronal precursors isolated from these samples undergo in vitro the cytoskeletal reorganization inherent to the neurodevelopment process which has been described as one important feature in the etiology of both diseases. In this paper, we will review the current knowledge on microtubular organization in olfactory neurons of patients with SZ and with BD that may constitute specific cytoskeletal endophenotypes and their relation with alterations in L-type voltage-activated Ca(2+) currents. Finally, the potential usefulness of neuronal precursors for pharmacological screening will be discussed.
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Affiliation(s)
- G Benítez-King
- Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Mexico.
| | - M Valdés-Tovar
- Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Mexico
| | - C Trueta
- Departamento de Neurofisiología, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz (INPRFM), Calzada México-Xochimilco No. 101, Col. San Lorenzo-Huipulco, C.P. 14370, Tlalpan, Distrito Federal, Mexico
| | - T Galván-Arrieta
- Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Mexico
| | - J Argueta
- Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Mexico
| | - S Alarcón
- Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Mexico
| | - A Lora-Castellanos
- Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Mexico
| | - H Solís-Chagoyán
- Laboratorio de Neurofarmacología, Subdirección de Investigaciones Clínicas, Mexico
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CRISPR/Cas9 facilitates investigation of neural circuit disease using human iPSCs: mechanism of epilepsy caused by an SCN1A loss-of-function mutation. Transl Psychiatry 2016; 6:e703. [PMID: 26731440 PMCID: PMC5068877 DOI: 10.1038/tp.2015.203] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Accepted: 11/10/2015] [Indexed: 11/10/2022] Open
Abstract
Mutations in SCN1A, the gene encoding the α subunit of Nav1.1 channel, can cause epilepsies with wide ranges of clinical phenotypes, which are associated with the contrasting effects of channel loss-of-function or gain-of-function. In this project, CRISPR/Cas9- and TALEN-mediated genome-editing techniques were applied to induced pluripotent stem cell (iPSC)-based-disease model to explore the mechanism of epilepsy caused by SCN1A loss-of-function mutation. By fluorescently labeling GABAergic subtype in iPSC-derived neurons using CRISPR/Cas9, we for the first time performed electrophysiological studies on SCN1A-expressing neural subtype and monitored the postsynaptic activity of both inhibitory and excitatory types. We found that the mutation c.A5768G, which led to no current of Nav1.1 in exogenously transfected system, influenced the properties of not only Nav current amount, but also Nav activation in Nav1.1-expressing GABAergic neurons. The two alterations in Nav further reduced the amplitudes and enhanced the thresholds of action potential in patient-derived GABAergic neurons, and led to weakened spontaneous inhibitory postsynaptic currents (sIPSCs) in the patient-derived neuronal network. Although the spontaneous excitatory postsynaptic currents (sEPSCs) did not change significantly, when the frequencies of both sIPSCs and sEPSCs were further analyzed, we found the whole postsynaptic activity transferred from the inhibition-dominated state to excitation in patient-derived neuronal networks, suggesting that changes in sIPSCs alone were sufficient to significantly reverse the excitatory level of spontaneous postsynaptic activity. In summary, our findings fill the gap of our knowledge regarding the relationship between SCN1A mutation effect recorded on exogenously transfected cells and on Nav1.1-expressing neurons, and reveal the physiological basis underlying epileptogenesis caused by SCN1A loss-of-function mutation.
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Miceli F, Soldovieri MV, Ambrosino P, De Maria M, Manocchio L, Medoro A, Taglialatela M. Molecular pathophysiology and pharmacology of the voltage-sensing module of neuronal ion channels. Front Cell Neurosci 2015; 9:259. [PMID: 26236192 PMCID: PMC4502356 DOI: 10.3389/fncel.2015.00259] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 06/22/2015] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated ion channels (VGICs) are membrane proteins that switch from a closed to open state in response to changes in membrane potential, thus enabling ion fluxes across the cell membranes. The mechanism that regulate the structural rearrangements occurring in VGICs in response to changes in membrane potential still remains one of the most challenging topic of modern biophysics. Na+, Ca2+ and K+ voltage-gated channels are structurally formed by the assembly of four similar domains, each comprising six transmembrane segments. Each domain can be divided into two main regions: the Pore Module (PM) and the Voltage-Sensing Module (VSM). The PM (helices S5 and S6 and intervening linker) is responsible for gate opening and ion selectivity; by contrast, the VSM, comprising the first four transmembrane helices (S1–S4), undergoes the first conformational changes in response to membrane voltage variations. In particular, the S4 segment of each domain, which contains several positively charged residues interspersed with hydrophobic amino acids, is located within the membrane electric field and plays an essential role in voltage sensing. In neurons, specific gating properties of each channel subtype underlie a variety of biological events, ranging from the generation and propagation of electrical impulses, to the secretion of neurotransmitters and to the regulation of gene expression. Given the important functional role played by the VSM in neuronal VGICs, it is not surprising that various VSM mutations affecting the gating process of these channels are responsible for human diseases, and that compounds acting on the VSM have emerged as important investigational tools with great therapeutic potential. In the present review we will briefly describe the most recent discoveries concerning how the VSM exerts its function, how genetically inherited diseases caused by mutations occurring in the VSM affects gating in VGICs, and how several classes of drugs and toxins selectively target the VSM.
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Affiliation(s)
- Francesco Miceli
- Department of Neuroscience, University of Naples Federico II Naples, Italy
| | | | - Paolo Ambrosino
- Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
| | - Michela De Maria
- Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
| | - Laura Manocchio
- Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
| | - Alessandro Medoro
- Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
| | - Maurizio Taglialatela
- Department of Neuroscience, University of Naples Federico II Naples, Italy ; Department of Medicine and Health Sciences, University of Molise Campobasso, Italy
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Baroni D, Moran O. On the multiple roles of the voltage gated sodium channel β1 subunit in genetic diseases. Front Pharmacol 2015; 6:108. [PMID: 26042039 PMCID: PMC4434899 DOI: 10.3389/fphar.2015.00108] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 05/06/2015] [Indexed: 11/13/2022] Open
Abstract
Voltage-gated sodium channels are intrinsic plasma membrane proteins that initiate the action potential in electrically excitable cells. They are composed of a pore-forming α-subunit and associated β-subunits. The β1-subunit was the first accessory subunit to be cloned. It can be important for controlling cell excitability and modulating multiple aspects of sodium channel physiology. Mutations of β1 are implicated in a wide variety of inherited pathologies, including epilepsy and cardiac conduction diseases. This review summarizes β1-subunit related channelopathies pointing out the current knowledge concerning their genetic background and their underlying molecular mechanisms.
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Affiliation(s)
- Debora Baroni
- Istituto di Biofisica - Consiglio Nazionale delle Ricerche, Genova Italy
| | - Oscar Moran
- Istituto di Biofisica - Consiglio Nazionale delle Ricerche, Genova Italy
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40
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Willis BC, Ponce-Balbuena D, Jalife J. Protein assemblies of sodium and inward rectifier potassium channels control cardiac excitability and arrhythmogenesis. Am J Physiol Heart Circ Physiol 2015; 308:H1463-73. [PMID: 25862830 DOI: 10.1152/ajpheart.00176.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/06/2015] [Indexed: 02/07/2023]
Abstract
The understanding of how cardiac ion channels function in the normal and the diseased heart has greatly increased over the last four decades thanks to the advent of patch-clamp technology and, more recently, the emergence of genetics, as well as cellular and molecular cardiology. However, our knowledge of how these membrane-embedded proteins physically interact with each other within macromolecular complexes remains incomplete. This review focuses on how the main cardiac inward sodium channel (NaV1.5) and the strong inward rectifier potassium channel (Kir2.1) function within macromolecular complexes to control cardiac excitability. It has become increasingly clear that these two important ion channel proteins physically interact with multiple other protein partners and with each other from early stages of protein trafficking and targeting through membrane anchoring, recycling, and degradation. Recent findings include compartmentalized regulation of NaV1.5 channel expression and function through a PDZ (postsynaptic density protein, Drosophila disc large tumor suppressor, and zonula occludens-1 protein) domain-binding motif, and interaction of caveolin-3 with Kir2.1 and ankyrin-G as a molecular platform for NaV1.5 signaling. At the cardiomyocyte membrane, NaV1.5 and Kir2.1 interact through at least two distinct PDZ domain-scaffolding proteins (synapse-associated protein-97 and α1-syntrophin), thus modulating reciprocally their cell-surface expression at two different microdomains. Emerging evidence also shows that inheritable mutations in plakophilin-2, ankyrin-G, dystrophin, syntrophin, synapse-associated protein-97, and caveolin-3, among others, modify functional expression and/or localization in the cardiac cell of NaV1.5, Kir2.1 or both to give rise to arrhythmogenic diseases. Unveiling the mechanistic underpinnings of macromolecular interactions should increase our understanding of inherited and acquired arrhythmogenic cardiac diseases and may lead to advances in therapy.
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Affiliation(s)
- B Cicero Willis
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and
| | - Daniela Ponce-Balbuena
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and
| | - José Jalife
- Department of Internal Medicine and Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan; and Centro Nacional de Investigaciones Cardiovasculares, Madrid, Spain
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Impaired action potential initiation in GABAergic interneurons causes hyperexcitable networks in an epileptic mouse model carrying a human Na(V)1.1 mutation. J Neurosci 2015; 34:14874-89. [PMID: 25378155 DOI: 10.1523/jneurosci.0721-14.2014] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mutations in SCN1A and other ion channel genes can cause different epileptic phenotypes, but the precise mechanisms underlying the development of hyperexcitable networks are largely unknown. Here, we present a multisystem analysis of an SCN1A mouse model carrying the NaV1.1-R1648H mutation, which causes febrile seizures and epilepsy in humans. We found a ubiquitous hypoexcitability of interneurons in thalamus, cortex, and hippocampus, without detectable changes in excitatory neurons. Interestingly, somatic Na(+) channels in interneurons and persistent Na(+) currents were not significantly changed. Instead, the key mechanism of interneuron dysfunction was a deficit of action potential initiation at the axon initial segment that was identified by analyzing action potential firing. This deficit increased with the duration of firing periods, suggesting that increased slow inactivation, as recorded for recombinant mutated channels, could play an important role. The deficit in interneuron firing caused reduced action potential-driven inhibition of excitatory neurons as revealed by less frequent spontaneous but not miniature IPSCs. Multiple approaches indicated increased spontaneous thalamocortical and hippocampal network activity in mutant mice, as follows: (1) more synchronous and higher-frequency firing was recorded in primary neuronal cultures plated on multielectrode arrays; (2) thalamocortical slices examined by field potential recordings revealed spontaneous activities and pathological high-frequency oscillations; and (3) multineuron Ca(2+) imaging in hippocampal slices showed increased spontaneous neuronal activity. Thus, an interneuron-specific generalized defect in action potential initiation causes multisystem disinhibition and network hyperexcitability, which can well explain the occurrence of seizures in the studied mouse model and in patients carrying this mutation.
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42
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Bechi G, Rusconi R, Cestèle S, Striano P, Franceschetti S, Mantegazza M. Rescuable folding defective NaV1.1 (SCN1A) mutants in epilepsy: properties, occurrence, and novel rescuing strategy with peptides targeted to the endoplasmic reticulum. Neurobiol Dis 2015; 75:100-14. [PMID: 25576396 DOI: 10.1016/j.nbd.2014.12.028] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 12/23/2014] [Accepted: 12/26/2014] [Indexed: 12/17/2022] Open
Abstract
Mutations of the voltage gated Na(+) channel Na(V)1.1 (SCN1A) are important causes of different genetic epilepsies and can also cause familial hemiplegic migraine (FHM-III). In previous studies, some rescuable epileptogenic folding defective mutants located in domain IV of Na(V)1.1 have been identified, showing partial loss of function also with maximal rescue. Variable rescue may be one of the causes of phenotypic variability, and rescue might be exploited for therapeutic approaches. Recently, we have identified a folding defective FHM-III Na(V)1.1 mutant that showed overall gain of function when rescued, consistent with a differential pathomechanism. Here, we have evaluated functional properties and cell surface expression of six Na(V)1.1 epileptogenic missense mutations in different rescuing conditions, including a novel one that we have developed expressing a selective sodium channel toxin (CsEI) targeted to the endoplasmic reticulum (ER). All the mutants showed loss of function and reduced cell surface expression, consistently with possibility of rescue. Four of them were rescuable by incubation at low temperature and interactions with different co-expressed proteins or a pharmacological chaperone (phenytoin). Notably, CsEI was able to rescue four mutants. Thus, Na(V)1.1 folding defective mutants can be relatively common and mutations inducing rescuable folding defects are spread in all Na(V)1.1 domains. Importantly, epileptogenic mutants showed overall loss of function even upon rescue, differently than FHM-III ones. The effectiveness of CsEI demonstrates that interactions in the ER are sufficient for inducing rescue, and provides a proof of concept for developing possible therapeutic approaches that may overcome some limitations of pharmacological chaperones.
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Affiliation(s)
- Giulia Bechi
- Department of Neurophysiopathology, Epilepsy Center, C. Besta Foundation Neurological Institute, 20133 Milano, Italy
| | - Raffaella Rusconi
- Institute of Molecular and Cellular Pharmacology (IPMC), LabEx ICST, CNRS UMR7275 and University of Nice-Sophia Antipolis, 06560 Valbonne, France
| | - Sandrine Cestèle
- Institute of Molecular and Cellular Pharmacology (IPMC), LabEx ICST, CNRS UMR7275 and University of Nice-Sophia Antipolis, 06560 Valbonne, France
| | - Pasquale Striano
- Pediatric Neurology and Neuromuscular Diseases Unit, Department of Neurosciences, Institute G. Gaslini, University of Genova, Genova, Italy
| | - Silvana Franceschetti
- Department of Neurophysiopathology, Epilepsy Center, C. Besta Foundation Neurological Institute, 20133 Milano, Italy
| | - Massimo Mantegazza
- Institute of Molecular and Cellular Pharmacology (IPMC), LabEx ICST, CNRS UMR7275 and University of Nice-Sophia Antipolis, 06560 Valbonne, France.
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Abstract
Voltage-gated sodium channels initiate action potentials in brain neurons, mutations in sodium channels cause inherited forms of epilepsy, and sodium channel blockers-along with other classes of drugs-are used in therapy of epilepsy. A mammalian voltage-gated sodium channel is a complex containing a large, pore-forming α subunit and one or two smaller β subunits. Extensive structure-function studies have revealed many aspects of the molecular basis for sodium channel structure, and X-ray crystallography of ancestral bacterial sodium channels has given insight into their three-dimensional structure. Mutations in sodium channel α and β subunits are responsible for genetic epilepsy syndromes with a wide range of severity, including generalized epilepsy with febrile seizures plus (GEFS+), Dravet syndrome, and benign familial neonatal-infantile seizures. These seizure syndromes are treated with antiepileptic drugs that offer differing degrees of success. The recent advances in understanding of disease mechanisms and sodium channel structure promise to yield improved therapeutic approaches.
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Affiliation(s)
- William A Catterall
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280;
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Subaran RL, Greenberg DA. The Genetics of Common Epilepsy Disorders: Lessons Learned from the Channelopathy Era. CURRENT GENETIC MEDICINE REPORTS 2014. [DOI: 10.1007/s40142-014-0040-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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45
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Volkers L, Kahlig KM, Das JHG, van Kempen MJA, Lindhout D, Koeleman BPC, Rook MB. Febrile temperatures unmask biophysical defects in Nav1.1 epilepsy mutations supportive of seizure initiation. ACTA ACUST UNITED AC 2014; 142:641-53. [PMID: 24277604 PMCID: PMC3840920 DOI: 10.1085/jgp.201311042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Generalized epilepsy with febrile seizures plus (GEFS+) is an early onset febrile epileptic syndrome with therapeutic responsive (a)febrile seizures continuing later in life. Dravet syndrome (DS) or severe myoclonic epilepsy of infancy has a complex phenotype including febrile generalized or hemiclonic convulsions before the age of 1, followed by intractable myoclonic, complex partial, or absence seizures. Both diseases can result from mutations in the Nav1.1 sodium channel, and initially, seizures are typically triggered by fever. We previously characterized two Nav1.1 mutants—R859H (GEFS+) and R865G (DS)—at room temperature and reported a mixture of biophysical gating defects that could not easily predict the phenotype presentation as either GEFS+ or DS. In this study, we extend the characterization of Nav1.1 wild-type, R859H, and R865G channels to physiological (37°C) and febrile (40°C) temperatures. At physiological temperature, a variety of biophysical defects were detected in both mutants, including a hyperpolarized shift in the voltage dependence of activation and a delayed recovery from fast and slow inactivation. Interestingly, at 40°C we also detected additional gating defects for both R859H and R865G mutants. The GEFS+ mutant R859H showed a loss of function in the voltage dependence of inactivation and an increased channel use-dependency at 40°C with no reduction in peak current density. The DS mutant R865G exhibited reduced peak sodium currents, enhanced entry into slow inactivation, and increased use-dependency at 40°C. Our results suggest that fever-induced temperatures exacerbate the gating defects of R859H or R865G mutants and may predispose mutation carriers to febrile seizures.
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Affiliation(s)
- Linda Volkers
- Department of Medical Genetics, Division of Biomedical Genetics, and 2 Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, 3508 AB Utrecht, Netherlands
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46
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Ohba C, Kato M, Takahashi S, Lerman-Sagie T, Lev D, Terashima H, Kubota M, Kawawaki H, Matsufuji M, Kojima Y, Tateno A, Goldberg-Stern H, Straussberg R, Marom D, Leshinsky-Silver E, Nakashima M, Nishiyama K, Tsurusaki Y, Miyake N, Tanaka F, Matsumoto N, Saitsu H. Early onset epileptic encephalopathy caused by de novoSCN8Amutations. Epilepsia 2014; 55:994-1000. [DOI: 10.1111/epi.12668] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/22/2014] [Indexed: 12/13/2022]
Affiliation(s)
- Chihiro Ohba
- Department of Human Genetics; Graduate School of Medicine; Yokohama City University; Yokohama Japan
- Department of Clinical Neurology and Stroke Medicine; Yokohama City University; Yokohama Japan
| | - Mitsuhiro Kato
- Department of Pediatrics; Yamagata University Faculty of Medicine; Yamagata Japan
| | - Satoru Takahashi
- Department of Pediatrics; Asahikawa Medical University; Asahikawa Japan
| | | | - Dorit Lev
- Metabolic Neurogenetic Clinic; Wolfson Medical Center; Holon Israel
| | - Hiroshi Terashima
- Division of Neurology; National Center for Child Health and Development; Tokyo Japan
| | - Masaya Kubota
- Division of Neurology; National Center for Child Health and Development; Tokyo Japan
| | - Hisashi Kawawaki
- Department of Pediatric Neurology; Osaka City General Hospital; Osaka Japan
| | - Mayumi Matsufuji
- Department of Pediatrics; Japan Community Health Care Organization Kyusyu Hospital; Kitakyushu Japan
| | - Yasuko Kojima
- Department of Pediatrics; Toho University Sakura Medical Center; Chiba Japan
| | - Akihiko Tateno
- Department of Pediatrics; Toho University Sakura Medical Center; Chiba Japan
| | | | - Rachel Straussberg
- Department of Neurogenetics; Schneider's Children Medical Center; Petah Tiqwa Israel
| | - Dafna Marom
- Department of Neurogenetics; Schneider's Children Medical Center; Petah Tiqwa Israel
| | | | - Mitsuko Nakashima
- Department of Human Genetics; Graduate School of Medicine; Yokohama City University; Yokohama Japan
| | - Kiyomi Nishiyama
- Department of Human Genetics; Graduate School of Medicine; Yokohama City University; Yokohama Japan
| | - Yoshinori Tsurusaki
- Department of Human Genetics; Graduate School of Medicine; Yokohama City University; Yokohama Japan
| | - Noriko Miyake
- Department of Human Genetics; Graduate School of Medicine; Yokohama City University; Yokohama Japan
| | - Fumiaki Tanaka
- Department of Clinical Neurology and Stroke Medicine; Yokohama City University; Yokohama Japan
| | - Naomichi Matsumoto
- Department of Human Genetics; Graduate School of Medicine; Yokohama City University; Yokohama Japan
| | - Hirotomo Saitsu
- Department of Human Genetics; Graduate School of Medicine; Yokohama City University; Yokohama Japan
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47
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Guerrini R, Marini C, Mantegazza M. Genetic epilepsy syndromes without structural brain abnormalities: clinical features and experimental models. Neurotherapeutics 2014; 11:269-85. [PMID: 24664660 PMCID: PMC3996114 DOI: 10.1007/s13311-014-0267-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Research in genetics of epilepsy represents an area of great interest both for clinical purposes and for understanding the basic mechanisms of epilepsy. Most mutations in epilepsies without structural brain abnormalities have been identified in ion channel genes, but an increasing number of genes involved in a diversity of functional and developmental processes are being recognized through whole exome or genome sequencing. Targeted molecular diagnosis is now available for different forms of epilepsy. The identification of epileptogenic mutations in patients before epilepsy onset and the possibility of developing therapeutic strategies tested in experimental models may facilitate experimental approaches that prevent epilepsy or decrease its severity. Functional analysis is essential for better understanding pathogenic mechanisms and gene interactions. In vitro experimental systems are either cells that usually do not express the protein of interest or neurons in primary cultures. In vivo/ex vivo systems are organisms or preparations obtained from them (e.g., brain slices), which should better model the complexity of brain circuits and actual pathophysiological conditions. Neurons differentiated from induced pluripotent stem cells generated from the skin fibroblasts of patients have recently allowed the study of mutations in human neurons having the genetic background of a given patient. However, there is remarkable complexity underlying epileptogenesis in the clinical dimension, as reflected by the fact that experimental models have not provided yet results having clinical translation and that, with a few exceptions concerning rare conditions, no new curative treatment has emerged from any genetic finding in epilepsy.
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Affiliation(s)
- Renzo Guerrini
- Pediatric Neurology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Viale Pieraccini 24, 50139, Florence, Italy,
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Calhoun JD, Isom LL. The role of non-pore-forming β subunits in physiology and pathophysiology of voltage-gated sodium channels. Handb Exp Pharmacol 2014; 221:51-89. [PMID: 24737232 DOI: 10.1007/978-3-642-41588-3_4] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Voltage-gated sodium channel β1 and β2 subunits were discovered as auxiliary proteins that co-purify with pore-forming α subunits in brain. The other family members, β1B, β3, and β4, were identified by homology and shown to modulate sodium current in heterologous systems. Work over the past 2 decades, however, has provided strong evidence that these proteins are not simply ancillary ion channel subunits, but are multifunctional signaling proteins in their own right, playing both conducting (channel modulatory) and nonconducting roles in cell signaling. Here, we discuss evidence that sodium channel β subunits not only regulate sodium channel function and localization but also modulate voltage-gated potassium channels. In their nonconducting roles, VGSC β subunits function as immunoglobulin superfamily cell adhesion molecules that modulate brain development by influencing cell proliferation and migration, axon outgrowth, axonal fasciculation, and neuronal pathfinding. Mutations in genes encoding β subunits are linked to paroxysmal diseases including epilepsy, cardiac arrhythmia, and sudden infant death syndrome. Finally, β subunits may be targets for the future development of novel therapeutics.
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Affiliation(s)
- Jeffrey D Calhoun
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA
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50
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Gambardella A, Labate A. The role of calcium channel mutations in human epilepsy. PROGRESS IN BRAIN RESEARCH 2014; 213:87-96. [DOI: 10.1016/b978-0-444-63326-2.00004-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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