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Miyazaki Y, Otsuka T, Yamagata Y, Endo T, Sanbo M, Sano H, Kobayashi K, Inahashi H, Kornau HC, Schmitz D, Prüss H, Meijer D, Hirabayashi M, Fukata Y, Fukata M. Oligodendrocyte-derived LGI3 and its receptor ADAM23 organize juxtaparanodal Kv1 channel clustering for short-term synaptic plasticity. Cell Rep 2024; 43:113634. [PMID: 38194969 PMCID: PMC10828548 DOI: 10.1016/j.celrep.2023.113634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 10/31/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024] Open
Abstract
Neurodevelopmental disorders, such as intellectual disability (ID), epilepsy, and autism, involve altered synaptic transmission and plasticity. Functional characterization of their associated genes is vital for understanding physio-pathological brain functions. LGI3 is a recently recognized ID-associated gene encoding a secretory protein related to an epilepsy-gene product, LGI1. Here, we find that LGI3 is uniquely secreted from oligodendrocytes in the brain and enriched at juxtaparanodes of myelinated axons, forming nanoscale subclusters. Proteomic analysis using epitope-tagged Lgi3 knockin mice shows that LGI3 uses ADAM23 as a receptor and selectively co-assembles with Kv1 channels. A lack of Lgi3 in mice disrupts juxtaparanodal clustering of ADAM23 and Kv1 channels and suppresses Kv1-channel-mediated short-term synaptic plasticity. Collectively, this study identifies an extracellular organizer of juxtaparanodal Kv1 channel clustering for finely tuned synaptic transmission. Given the defective secretion of the LGI3 missense variant, we propose a molecular pathway, the juxtaparanodal LGI3-ADAM23-Kv1 channel, for understanding neurodevelopmental disorders.
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Affiliation(s)
- Yuri Miyazaki
- Division of Neuropharmacology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan; Division of Membrane Physiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Takeshi Otsuka
- Section of Cellular Electrophysiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi 444-8585, Japan
| | - Yoko Yamagata
- Section of Multilayer Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8585, Japan
| | | | - Makoto Sanbo
- Section of Mammalian Transgenesis, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Hiromi Sano
- Division of Behavioral Neuropharmacology, International Center for Brain Science, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Kenta Kobayashi
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi 444-8585, Japan; Section of Viral Vector Development, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8585, Japan
| | - Hiroki Inahashi
- Division of Membrane Physiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Hans-Christian Kornau
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany; Neuroscience Research Center (NWFZ), Cluster NeuroCure, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Dietmar Schmitz
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany; Neuroscience Research Center (NWFZ), Cluster NeuroCure, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Harald Prüss
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany; Helmholtz Innovation Lab BaoBab (Brain Antibody-omics and B-cell Lab), Berlin, Germany; Department of Neurology and Experimental Neurology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Dies Meijer
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK; Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK
| | - Masumi Hirabayashi
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi 444-8585, Japan; Section of Mammalian Transgenesis, Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Yuko Fukata
- Division of Membrane Physiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Division of Molecular and Cellular Pharmacology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
| | - Masaki Fukata
- Division of Neuropharmacology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan; Division of Membrane Physiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi 444-8585, Japan.
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Smith J, Richerson G, Kouchi H, Duprat F, Mantegazza M, Bezin L, Rheims S. Are we there yet? A critical evaluation of sudden and unexpected death in epilepsy models. Epilepsia 2024; 65:9-25. [PMID: 37914406 DOI: 10.1111/epi.17812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/11/2023] [Accepted: 10/31/2023] [Indexed: 11/03/2023]
Abstract
Although animal models have helped to elaborate meaningful hypotheses about the pathophysiology of sudden and unexpected death in epilepsy (SUDEP), specific prevention strategies are still lacking, potentially reflecting the limitations of these models and the intrinsic difficulties of investigating SUDEP. The interpretation of preclinical data and their translation to diagnostic and therapeutic developments in patients thus require a high level of confidence in their relevance to model the human situation. Preclinical models of SUDEP are heterogeneous and include rodent and nonrodent species. A critical aspect is whether the animals have isolated seizures exclusively induced by a specific trigger, such as models where seizures are elicited by electrical stimulation, pharmacological intervention, or DBA mouse strains, or whether they suffer from epilepsy with spontaneous seizures, with or without spontaneous SUDEP, either of nongenetic epilepsy etiology or from genetically based developmental and epileptic encephalopathies. All these models have advantages and potential disadvantages, but it is important to be aware of these limitations to interpret data appropriately in a translational perspective. The majority of models with spontaneous seizures are of a genetic basis, whereas SUDEP cases with a genetic basis represent only a small proportion of the total number. In almost all models, cardiorespiratory arrest occurs during the course of the seizure, contrary to that in patients observed at the time of death, potentially raising the issue of whether we are studying models of SUDEP or models of periseizure death. However, some of these limitations are impossible to avoid and can in part be dependent on specific features of SUDEP, which may be difficult to model. Several preclinical tools are available to address certain gaps in SUDEP pathophysiology, which can be used to further validate current preclinical models.
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Affiliation(s)
- Jonathon Smith
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - George Richerson
- Department of Neurology, University of Iowa, Iowa City, Iowa, USA
| | - Hayet Kouchi
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - Fabrice Duprat
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- University Cote d'Azur, Valbonne-Sophia Antipolis, France
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne-Sophia Antipolis, France
- Inserm, Valbonne-Sophia Antipolis, France
| | - Laurent Bezin
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
| | - Sylvain Rheims
- Lyon Neuroscience Research Center (CRNL, INSERM U1028/CNRS UMR 5292, Lyon 1 University), Lyon, France
- Department of Functional Neurology and Epileptology, Hospices Civils de Lyon and Lyon 1 University, Lyon, France
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Zhao R, Qasim A, Sophanpanichkul P, Dai H, Nayak M, Sher I, Chill J, Goldstein SAN. Selective block of human Kv1.1 channels and an epilepsy-associated gain-of-function mutation by AETX-K peptide. FASEB J 2024; 38:e23381. [PMID: 38102952 PMCID: PMC10754259 DOI: 10.1096/fj.202302061r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/11/2023] [Accepted: 12/05/2023] [Indexed: 12/17/2023]
Abstract
Dysfunction of the human voltage-gated K+ channel Kv1.1 has been associated with epilepsy, multiple sclerosis, episodic ataxia, myokymia, and cardiorespiratory dysregulation. We report here that AETX-K, a sea anemone type I (SAK1) peptide toxin we isolated from a phage display library, blocks Kv1.1 with high affinity (Ki ~ 1.6 pM) and notable specificity, inhibiting other Kv channels we tested a million-fold less well. Nuclear magnetic resonance (NMR) was employed both to determine the three-dimensional structure of AETX-K, showing it to employ a classic SAK1 scaffold while exhibiting a unique electrostatic potential surface, and to visualize AETX-K bound to the Kv1.1 pore domain embedded in lipoprotein nanodiscs. Study of Kv1.1 in Xenopus oocytes with AETX-K and point variants using electrophysiology demonstrated the blocking mechanism to employ a toxin-channel configuration we have described before whereby AETX-K Lys23 , two positions away on the toxin interaction surface from the classical blocking residue, enters the pore deeply enough to interact with K+ ions traversing the pathway from the opposite side of the membrane. The mutant channel Kv1.1-L296 F is associated with pharmaco-resistant multifocal epilepsy in infants because it significantly increases K+ currents by facilitating opening and slowing closure of the channels. Consistent with the therapeutic potential of AETX-K for Kv1.1 gain-of-function-associated diseases, AETX-K at 4 pM decreased Kv1.1-L296 F currents to wild-type levels; further, populations of heteromeric channels formed by co-expression Kv1.1 and Kv1.2, as found in many neurons, showed a Ki of ~10 nM even though homomeric Kv1.2 channels were insensitive to the toxin (Ki > 2000 nM).
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Affiliation(s)
- Ruiming Zhao
- Departments of Pediatrics, Physiology & Biophysics, and Pharmaceutical Sciences, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, Irvine, CA 92697, USA
| | - Arwa Qasim
- Department of Chemistry, Bar Ilan University, Ramat Gan, 52900, Israel
| | - Punyanuch Sophanpanichkul
- Departments of Pediatrics, Physiology & Biophysics, and Pharmaceutical Sciences, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, Irvine, CA 92697, USA
| | - Hui Dai
- Departments of Pediatrics, Physiology & Biophysics, and Pharmaceutical Sciences, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, Irvine, CA 92697, USA
| | - Maha Nayak
- Departments of Pediatrics, Physiology & Biophysics, and Pharmaceutical Sciences, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, Irvine, CA 92697, USA
| | - Inbal Sher
- Department of Chemistry, Bar Ilan University, Ramat Gan, 52900, Israel
| | - Jordan Chill
- Department of Chemistry, Bar Ilan University, Ramat Gan, 52900, Israel
| | - Steve A. N. Goldstein
- Departments of Pediatrics, Physiology & Biophysics, and Pharmaceutical Sciences, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, Irvine, CA 92697, USA
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AlShammari AK, Abd El-Aziz TM, Al-Sabi A. Snake Venom: A Promising Source of Neurotoxins Targeting Voltage-Gated Potassium Channels. Toxins (Basel) 2023; 16:12. [PMID: 38251229 PMCID: PMC10820993 DOI: 10.3390/toxins16010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/11/2023] [Accepted: 12/19/2023] [Indexed: 01/23/2024] Open
Abstract
The venom derived from various sources of snakes represents a vast collection of predominantly protein-based toxins that exhibit a wide range of biological actions, including but not limited to inflammation, pain, cytotoxicity, cardiotoxicity, and neurotoxicity. The venom of a particular snake species is composed of several toxins, while the venoms of around 600 venomous snake species collectively encompass a substantial reservoir of pharmacologically intriguing compounds. Despite extensive research efforts, a significant portion of snake venoms remains uncharacterized. Recent findings have demonstrated the potential application of neurotoxins derived from snake venom in selectively targeting voltage-gated potassium channels (Kv). These neurotoxins include BPTI-Kunitz polypeptides, PLA2 neurotoxins, CRISPs, SVSPs, and various others. This study provides a comprehensive analysis of the existing literature on the significance of Kv channels in various tissues, highlighting their crucial role as proteins susceptible to modulation by diverse snake venoms. These toxins have demonstrated potential as valuable pharmacological resources and research tools for investigating the structural and functional characteristics of Kv channels.
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Affiliation(s)
- Altaf K. AlShammari
- College of Engineering and Technology, American University of the Middle East, Egaila 54200, Kuwait;
| | - Tarek Mohamed Abd El-Aziz
- Zoology Department, Faculty of Science, Minia University, El-Minia 61519, Egypt
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Ahmed Al-Sabi
- College of Engineering and Technology, American University of the Middle East, Egaila 54200, Kuwait;
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5
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Okoh J, Mays J, Bacq A, Oses-Prieto JA, Tyanova S, Chen CJ, Imanbeyev K, Doladilhe M, Zhou H, Jafar-Nejad P, Burlingame A, Noebels J, Baulac S, Costa-Mattioli M. Targeted suppression of mTORC2 reduces seizures across models of epilepsy. Nat Commun 2023; 14:7364. [PMID: 37963879 PMCID: PMC10645975 DOI: 10.1038/s41467-023-42922-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 10/26/2023] [Indexed: 11/16/2023] Open
Abstract
Epilepsy is a neurological disorder that poses a major threat to public health. Hyperactivation of mTOR complex 1 (mTORC1) is believed to lead to abnormal network rhythmicity associated with epilepsy, and its inhibition is proposed to provide some therapeutic benefit. However, mTOR complex 2 (mTORC2) is also activated in the epileptic brain, and little is known about its role in seizures. Here we discover that genetic deletion of mTORC2 from forebrain neurons is protective against kainic acid-induced behavioral and EEG seizures. Furthermore, inhibition of mTORC2 with a specific antisense oligonucleotide robustly suppresses seizures in several pharmacological and genetic mouse models of epilepsy. Finally, we identify a target of mTORC2, Nav1.2, which has been implicated in epilepsy and neuronal excitability. Our findings, which are generalizable to several models of human seizures, raise the possibility that inhibition of mTORC2 may serve as a broader therapeutic strategy against epilepsy.
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Affiliation(s)
- James Okoh
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Jacqunae Mays
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Alexandre Bacq
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Juan A Oses-Prieto
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Stefka Tyanova
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Chien-Ju Chen
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Novartis Inc, Boston, MA, USA
| | - Khalel Imanbeyev
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Marion Doladilhe
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Hongyi Zhou
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | | | - Alma Burlingame
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Jeffrey Noebels
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Stephanie Baulac
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA.
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA.
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6
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Borges FS, Protachevicz PR, Souza DLM, Bittencourt CF, Gabrick EC, Bentivoglio LE, Szezech JD, Batista AM, Caldas IL, Dura-Bernal S, Pena RFO. The Roles of Potassium and Calcium Currents in the Bistable Firing Transition. Brain Sci 2023; 13:1347. [PMID: 37759949 PMCID: PMC10527161 DOI: 10.3390/brainsci13091347] [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: 08/14/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
Healthy brains display a wide range of firing patterns, from synchronized oscillations during slow-wave sleep to desynchronized firing during movement. These physiological activities coexist with periods of pathological hyperactivity in the epileptic brain, where neurons can fire in synchronized bursts. Most cortical neurons are pyramidal regular spiking (RS) cells with frequency adaptation and do not exhibit bursts in current-clamp experiments (in vitro). In this work, we investigate the transition mechanism of spike-to-burst patterns due to slow potassium and calcium currents, considering a conductance-based model of a cortical RS cell. The joint influence of potassium and calcium ion channels on high synchronous patterns is investigated for different synaptic couplings (gsyn) and external current inputs (I). Our results suggest that slow potassium currents play an important role in the emergence of high-synchronous activities, as well as in the spike-to-burst firing pattern transitions. This transition is related to the bistable dynamics of the neuronal network, where physiological asynchronous states coexist with pathological burst synchronization. The hysteresis curve of the coefficient of variation of the inter-spike interval demonstrates that a burst can be initiated by firing states with neuronal synchronization. Furthermore, we notice that high-threshold (IL) and low-threshold (IT) ion channels play a role in increasing and decreasing the parameter conditions (gsyn and I) in which bistable dynamics occur, respectively. For high values of IL conductance, a synchronous burst appears when neurons are weakly coupled and receive more external input. On the other hand, when the conductance IT increases, higher coupling and lower I are necessary to produce burst synchronization. In light of our results, we suggest that channel subtype-specific pharmacological interactions can be useful to induce transitions from pathological high bursting states to healthy states.
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Affiliation(s)
- Fernando S. Borges
- Department of Physiology and Pharmacology, State University of New York Downstate Health Sciences University, Brooklyn, NY 11203, USA
- Center for Mathematics, Computation and Cognition, Federal University of ABC, São Bernardo do Campo 09606-045, Brazil
| | | | - Diogo L. M. Souza
- Graduate Program in Science, State University of Ponta Grossa, Ponta Grossa 84010-330, Brazil
| | - Conrado F. Bittencourt
- Graduate Program in Science, State University of Ponta Grossa, Ponta Grossa 84010-330, Brazil
| | - Enrique C. Gabrick
- Graduate Program in Science, State University of Ponta Grossa, Ponta Grossa 84010-330, Brazil
| | - Lucas E. Bentivoglio
- Graduate Program in Science, State University of Ponta Grossa, Ponta Grossa 84010-330, Brazil
| | - José D. Szezech
- Graduate Program in Science, State University of Ponta Grossa, Ponta Grossa 84010-330, Brazil
- Department of Mathematics and Statistics, State University of Ponta Grossa, Ponta Grossa 84030-900, Brazil
| | - Antonio M. Batista
- Graduate Program in Science, State University of Ponta Grossa, Ponta Grossa 84010-330, Brazil
- Department of Mathematics and Statistics, State University of Ponta Grossa, Ponta Grossa 84030-900, Brazil
| | - Iberê L. Caldas
- Institute of Physics, University of São Paulo, São Paulo 05508-090, Brazil
| | - Salvador Dura-Bernal
- Department of Physiology and Pharmacology, State University of New York Downstate Health Sciences University, Brooklyn, NY 11203, USA
- Center for Biomedical Imaging and Neuromodulation, The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA
| | - Rodrigo F. O. Pena
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL 33458, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, FL 33458, USA
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7
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Borges FS, Protachevicz PR, Souza DLM, Bittencourt CF, Gabrick EC, Bentivoglio LE, Szezech JD, Batista AM, Caldas IL, Dura-Bernal S, Pena RFO. The Role of Potassium and Calcium Currents in the Bistable Firing Transition. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553625. [PMID: 37645875 PMCID: PMC10462112 DOI: 10.1101/2023.08.16.553625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Healthy brains display a wide range of firing patterns, from synchronized oscillations during slowwave sleep to desynchronized firing during movement. These physiological activities coexist with periods of pathological hyperactivity in the epileptic brain, where neurons can fire in synchronized bursts. Most cortical neurons are pyramidal regular spiking cells (RS) with frequency adaptation and do not exhibit bursts in current-clamp experiments ( in vitro ). In this work, we investigate the transition mechanism of spike-to-burst patterns due to slow potassium and calcium currents, considering a conductance-based model of a cortical RS cell. The joint influence of potassium and calcium ion channels on high synchronous patterns is investigated for different synaptic couplings ( g syn ) and external current inputs ( I ). Our results suggest that slow potassium currents play an important role in the emergence of high-synchronous activities, as well as in the spike-to-burst firing pattern transitions. This transition is related to bistable dynamics of the neuronal network, where physiological asynchronous states coexist with pathological burst synchronization. The hysteresis curve of the coefficient of variation of the inter-spike interval demonstrates that a burst can be initiated by firing states with neuronal synchronization. Furthermore, we notice that high-threshold ( I L ) and low-threshold ( I T ) ion channels play a role in increasing and decreasing the parameter conditions ( g syn and I ) in which bistable dynamics occur, respectively. For high values of I L conductance, a synchronous burst appears when neurons are weakly coupled and receive more external input. On the other hand, when the conductance I T increases, higher coupling and lower I are necessary to produce burst synchronization. In light of our results, we suggest that channel subtype-specific pharmacological interactions can be useful to induce transitions from pathological high bursting states to healthy states.
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Affiliation(s)
- Fernando S Borges
- Department of Physiology and Pharmacology, State University of New York Downstate Health Sciences University, Brooklyn, New York, USA
- Center for Mathematics, Computation, and Cognition, Federal University of ABC, 09606-045 São Bernardo do Campo, SP, Brazil
| | | | - Diogo L M Souza
- Graduate Program in Science, State University of Ponta Grossa, 84030-900 Ponta Grossa, PR, Brazil
| | - Conrado F Bittencourt
- Graduate Program in Science, State University of Ponta Grossa, 84030-900 Ponta Grossa, PR, Brazil
| | - Enrique C Gabrick
- Graduate Program in Science, State University of Ponta Grossa, 84030-900 Ponta Grossa, PR, Brazil
| | - Lucas E Bentivoglio
- Graduate Program in Science, State University of Ponta Grossa, 84030-900 Ponta Grossa, PR, Brazil
| | - José D Szezech
- Graduate Program in Science, State University of Ponta Grossa, 84030-900 Ponta Grossa, PR, Brazil
- Department of Mathematics and Statistics, State University of Ponta Grossa, Ponta Grossa, Brazil
| | - Antonio M Batista
- Graduate Program in Science, State University of Ponta Grossa, 84030-900 Ponta Grossa, PR, Brazil
- Department of Mathematics and Statistics, State University of Ponta Grossa, Ponta Grossa, Brazil
| | - Iberê L Caldas
- Institute of Physics, University of São Paulo, 05508-090 São Paulo, SP, Brazil
| | - Salvador Dura-Bernal
- Department of Physiology and Pharmacology, State University of New York Downstate Health Sciences University, Brooklyn, New York, USA
- Center for Biomedical Imaging and Neuromodulation, The Nathan S. Kline Institute for Psychiatric Research, New York, USA
| | - Rodrigo F O Pena
- Department of Biological Sciences, Florida Atlantic University, Jupiter, Florida, USA
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Dogra D, Meza-Santoscoy PL, Gavrilovici C, Rehak R, de la Hoz CLR, Ibhazehiebo K, Rho JM, Kurrasch DM. kcna1a mutant zebrafish model episodic ataxia type 1 (EA1) with epilepsy and show response to first-line therapy carbamazepine. Epilepsia 2023; 64:2186-2199. [PMID: 37209379 DOI: 10.1111/epi.17659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 05/18/2023] [Accepted: 05/18/2023] [Indexed: 05/22/2023]
Abstract
OBJECTIVE KCNA1 mutations are associated with a rare neurological movement disorder known as episodic ataxia type 1 (EA1), and epilepsy is a common comorbidity. Current medications provide only partial relief for ataxia and/or seizures, making new drugs needed. Here, we characterized zebrafish kcna1a-/- as a model of EA1 with epilepsy and compared the efficacy of the first-line therapy carbamazepine in kcna1a-/- zebrafish to Kcna1-/- rodents. METHODS CRISPR/Cas9 mutagenesis was used to introduce a mutation in the sixth transmembrane segment of the zebrafish Kcna1 protein. Behavioral and electrophysiological assays were performed on kcna1a-/- larvae to assess ataxia- and epilepsy-related phenotypes. Real-time quantitative polymerase chain reaction (qPCR) was conducted to measure mRNA levels of brain hyperexcitability markers in kcna1a-/- larvae, followed by bioenergetics profiling to evaluate metabolic function. Drug efficacies were tested using behavioral and electrophysiological assessments, as well as seizure frequency in kcna1a-/- zebrafish and Kcna1-/- mice, respectively. RESULTS Zebrafish kcna1a-/- larvae showed uncoordinated movements and locomotor deficits, along with scoliosis and increased mortality. The mutants also exhibited impaired startle responses when exposed to light-dark flashes and acoustic stimulation as well as hyperexcitability as measured by extracellular field recordings and upregulated fosab transcripts. Neural vglut2a and gad1b transcript levels were disrupted in kcna1a-/- larvae, indicative of a neuronal excitatory/inhibitory imbalance, as well as a significant reduction in cellular respiration in kcna1a-/- , consistent with dysregulation of neurometabolism. Notably, carbamazepine suppressed the impaired startle response and brain hyperexcitability in kcna1a-/- zebrafish but had no effect on the seizure frequency in Kcna1-/- mice, suggesting that this EA1 zebrafish model might better translate to humans than rodents. SIGNIFICANCE We conclude that zebrafish kcna1a-/- show ataxia and epilepsy-related phenotypes and are responsive to carbamazepine treatment, consistent with EA1 patients. These findings suggest that kcna1-/- zebrafish are a useful model for drug screening as well as studying the underlying disease biology.
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Affiliation(s)
- Deepika Dogra
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Paola L Meza-Santoscoy
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Cezar Gavrilovici
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Departments of Pediatrics, Clinical Neurosciences, Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Departments of Neurosciences, Pediatrics, and Pharmacology, Rady Children's Hospital San Diego, University of California San Diego, San Diego, California, USA
| | - Renata Rehak
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Cristiane L R de la Hoz
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Kingsley Ibhazehiebo
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jong M Rho
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Departments of Pediatrics, Clinical Neurosciences, Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- Departments of Neurosciences, Pediatrics, and Pharmacology, Rady Children's Hospital San Diego, University of California San Diego, San Diego, California, USA
| | - Deborah M Kurrasch
- Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
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9
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Zhang LM, Chen L, Zhao YF, Duan WM, Zhong LM, Liu MW. Identification of key potassium channel genes of temporal lobe epilepsy by bioinformatics analyses and experimental verification. Front Neurol 2023; 14:1175007. [PMID: 37483435 PMCID: PMC10361730 DOI: 10.3389/fneur.2023.1175007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/16/2023] [Indexed: 07/25/2023] Open
Abstract
One of the most prevalent types of epilepsy is temporal lobe epilepsy (TLE), which has unknown etiological factors and drug resistance. The detailed mechanisms underlying potassium channels in human TLE have not yet been elucidated. Hence, this study aimed to mine potassium channel genes linked to TLE using a bioinformatic approach. The results found that Four key TLE-related potassium channel genes (TERKPCGs) were identified: potassium voltage-gated channel subfamily E member (KCNA) 1, KCNA2, potassium inwardly rectifying channel, subfamily J, member 11 (KCNJ11), and KCNS1. A protein-protein interaction (PPI) network was constructed to analyze the relationship between TERKPCGs and other key module genes. The results of gene set enrichment analysis (GSEA) for a single gene indicated that the four TERKPCGs were highly linked to the cation channel, potassium channel, respiratory chain, and oxidative phosphorylation. The mRNA-TF network was established using four mRNAs and 113 predicted transcription factors. A ceRNA network containing seven miRNAs, two mRNAs, and 244 lncRNAs was constructed based on the TERKPCGs. Three common small-molecule drugs (enflurane, promethazine, and miconazole) target KCNA1, KCNA2, and KCNS1. Ten small-molecule drugs (glimepiride, diazoxide, levosimendan, and thiamylal et al.) were retrieved for KCNJ11. Compared to normal mice, the expression of KCNA1, KCNA2, KCNJ11, and KCNS1 was downregulated in the brain tissue of the epilepsy mouse model at both the transcriptional and translational levels, which was consistent with the trend of human data from the public database. The results indicated that key potassium channel genes linked to TLE were identified based on bioinformatics analysis to investigate the potential significance of potassium channel genes in the development and treatment of TLE.
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Affiliation(s)
- Lin-ming Zhang
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
- Yunnan Provincial Clinical Research Center for Neurological Disease, Kunming, Yunnan, China
| | - Ling Chen
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
- Yunnan Provincial Clinical Research Center for Neurological Disease, Kunming, Yunnan, China
| | - Yi-fei Zhao
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
- Yunnan Provincial Clinical Research Center for Neurological Disease, Kunming, Yunnan, China
| | - Wei-mei Duan
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
- Yunnan Provincial Clinical Research Center for Neurological Disease, Kunming, Yunnan, China
| | - Lian-mei Zhong
- Department of Neurology, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
- Yunnan Provincial Clinical Research Center for Neurological Disease, Kunming, Yunnan, China
| | - Ming-wei Liu
- Department of Emergency, The First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
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10
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Dolma S, Joshi A. The Node of Ranvier as an Interface for Axo-Glial Interactions: Perturbation of Axo-Glial Interactions in Various Neurological Disorders. J Neuroimmune Pharmacol 2023; 18:215-234. [PMID: 37285016 DOI: 10.1007/s11481-023-10072-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 05/19/2023] [Indexed: 06/08/2023]
Abstract
The action potential conduction along the axon is highly dependent on the healthy interactions between the axon and myelin-producing glial cells. Myelin, which facilitates action potential, is the protective insulation around the axon formed by Schwann cells and oligodendrocytes in the peripheral (PNS) and central nervous system (CNS), respectively. Myelin is a continuous structure with intermittent gaps called nodes of Ranvier, which are the sites enriched with ion channels, transmembrane, scaffolding, and cytoskeletal proteins. Decades-long extensive research has identified a comprehensive proteome with strictly regularized localization at the node of Ranvier. Concurrently, axon-glia interactions at the node of Ranvier have gathered significant attention as the pathophysiological targets for various neurodegenerative disorders. Numerous studies have shown the alterations in the axon-glia interactions culminating in neurological diseases. In this review, we have provided an update on the molecular composition of the node of Ranvier. Further, we have discussed in detail the consequences of disruption of axon-glia interactions during the pathogenesis of various CNS and PNS disorders.
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Affiliation(s)
- Sonam Dolma
- Department of Pharmacy, Birla Institute of Technology and Sciences- Pilani, Hyderabad campus, Telangana state, India
| | - Abhijeet Joshi
- Department of Pharmacy, Birla Institute of Technology and Sciences- Pilani, Hyderabad campus, Telangana state, India.
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11
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Koch NA, Sonnenberg L, Hedrich UBS, Lauxmann S, Benda J. Loss or gain of function? Effects of ion channel mutations on neuronal firing depend on the neuron type. Front Neurol 2023; 14:1194811. [PMID: 37292138 PMCID: PMC10244640 DOI: 10.3389/fneur.2023.1194811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 05/03/2023] [Indexed: 06/10/2023] Open
Abstract
Introduction Clinically relevant mutations to voltage-gated ion channels, called channelopathies, alter ion channel function, properties of ionic currents, and neuronal firing. The effects of ion channel mutations are routinely assessed and characterized as loss of function (LOF) or gain of function (GOF) at the level of ionic currents. However, emerging personalized medicine approaches based on LOF/GOF characterization have limited therapeutic success. Potential reasons are among others that the translation from this binary characterization to neuronal firing is currently not well-understood-especially when considering different neuronal cell types. In this study, we investigate the impact of neuronal cell type on the firing outcome of ion channel mutations. Methods To this end, we simulated a diverse collection of single-compartment, conductance-based neuron models that differed in their composition of ionic currents. We systematically analyzed the effects of changes in ion current properties on firing in different neuronal types. Additionally, we simulated the effects of known mutations in KCNA1 gene encoding the KV1.1 potassium channel subtype associated with episodic ataxia type 1 (EA1). Results These simulations revealed that the outcome of a given change in ion channel properties on neuronal excitability depends on neuron type, i.e., the properties and expression levels of the unaffected ionic currents. Discussion Consequently, neuron-type specific effects are vital to a full understanding of the effects of channelopathies on neuronal excitability and are an important step toward improving the efficacy and precision of personalized medicine approaches.
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Affiliation(s)
- Nils A. Koch
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
| | - Lukas Sonnenberg
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
| | - Ulrike B. S. Hedrich
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Stephan Lauxmann
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Jan Benda
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany
- Bernstein Center for Computational Neuroscience Tübingen, Tübingen, Germany
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12
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Paulhus K, Glasscock E. Novel Genetic Variants Expand the Functional, Molecular, and Pathological Diversity of KCNA1 Channelopathy. Int J Mol Sci 2023; 24:8826. [PMID: 37240170 PMCID: PMC10219020 DOI: 10.3390/ijms24108826] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/11/2023] [Accepted: 05/13/2023] [Indexed: 05/28/2023] Open
Abstract
The KCNA1 gene encodes Kv1.1 voltage-gated potassium channel α subunits, which are crucial for maintaining healthy neuronal firing and preventing hyperexcitability. Mutations in the KCNA1 gene can cause several neurological diseases and symptoms, such as episodic ataxia type 1 (EA1) and epilepsy, which may occur alone or in combination, making it challenging to establish simple genotype-phenotype correlations. Previous analyses of human KCNA1 variants have shown that epilepsy-linked mutations tend to cluster in regions critical for the channel's pore, whereas EA1-associated mutations are evenly distributed across the length of the protein. In this review, we examine 17 recently discovered pathogenic or likely pathogenic KCNA1 variants to gain new insights into the molecular genetic basis of KCNA1 channelopathy. We provide the first systematic breakdown of disease rates for KCNA1 variants in different protein domains, uncovering potential location biases that influence genotype-phenotype correlations. Our examination of the new mutations strengthens the proposed link between the pore region and epilepsy and reveals new connections between epilepsy-related variants, genetic modifiers, and respiratory dysfunction. Additionally, the new variants include the first two gain-of-function mutations ever discovered for KCNA1, the first frameshift mutation, and the first mutations located in the cytoplasmic N-terminal domain, broadening the functional and molecular scope of KCNA1 channelopathy. Moreover, the recently identified variants highlight emerging links between KCNA1 and musculoskeletal abnormalities and nystagmus, conditions not typically associated with KCNA1. These findings improve our understanding of KCNA1 channelopathy and promise to enhance personalized diagnosis and treatment for individuals with KCNA1-linked disorders.
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Affiliation(s)
| | - Edward Glasscock
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA;
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13
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Kozar-Gillan N, Velichkova A, Kanatouris G, Eshed-Eisenbach Y, Steel G, Jaegle M, Aunin E, Peles E, Torsney C, Meijer DN. LGI3/2-ADAM23 interactions cluster Kv1 channels in myelinated axons to regulate refractory period. J Cell Biol 2023; 222:e202211031. [PMID: 36828548 PMCID: PMC9997507 DOI: 10.1083/jcb.202211031] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/18/2022] [Accepted: 01/17/2023] [Indexed: 02/26/2023] Open
Abstract
Along myelinated axons, Shaker-type potassium channels (Kv1) accumulate at high density in the juxtaparanodal region, directly adjacent to the paranodal axon-glia junctions that flank the nodes of Ranvier. However, the mechanisms that control the clustering of Kv1 channels, as well as their function at this site, are still poorly understood. Here we demonstrate that axonal ADAM23 is essential for both the accumulation and stability of juxtaparanodal Kv1 complexes. The function of ADAM23 is critically dependent on its interaction with its extracellular ligands LGI2 and LGI3. Furthermore, we demonstrate that juxtaparanodal Kv1 complexes affect the refractory period, thus enabling high-frequency burst firing of action potentials. Our findings not only reveal a previously unknown molecular pathway that regulates Kv1 channel clustering, but they also demonstrate that the juxtaparanodal Kv1 channels that are concealed below the myelin sheath, play a significant role in modifying axonal physiology.
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Affiliation(s)
- Nina Kozar-Gillan
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
| | | | - George Kanatouris
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
| | - Yael Eshed-Eisenbach
- Department of Molecular Cell Biology and Molecular Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Gavin Steel
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
| | | | - Eerik Aunin
- Biomedical Sciences, ErasmusMC, Rotterdam, Netherlands
| | - Elior Peles
- Department of Molecular Cell Biology and Molecular Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Carole Torsney
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh. UK
| | - Dies N. Meijer
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh. UK
- Muir Maxwell Epilepsy Centre, University of Edinburgh, Edinburgh, UK
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14
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George AG, Farrell JS, Colangeli R, Wall AK, Gom RC, Kesler MT, Rodriguez de la Hoz C, Villa BR, Perera T, Rho JM, Kurrasch D, Teskey GC. Sudden unexpected death in epilepsy is prevented by blocking postictal hypoxia. Neuropharmacology 2023; 231:109513. [PMID: 36948357 DOI: 10.1016/j.neuropharm.2023.109513] [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: 10/19/2022] [Revised: 02/21/2023] [Accepted: 03/18/2023] [Indexed: 03/24/2023]
Abstract
Epilepsy is at times a fatal disease. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of epilepsy-related mortality in people with intractable epilepsy and is defined by exclusion; non-accidental, non-toxicologic, and non-anatomic causes of death. While SUDEP often follows a bilateral tonic-clonic seizure, the mechanisms that ultimately lead to terminal apnea and then asystole remain elusive and there is a lack of preventative treatments. Based on the observation that discrete seizures lead to local and postictal vasoconstriction, resulting in hypoperfusion, hypoxia and behavioural disturbances in the forebrain we reasoned those similar mechanisms may play a role in SUDEP when seizures invade the brainstem. Here we tested this neurovascular-based hypothesis of SUDEP in awake non-anesthetized mice by pharmacologically preventing seizure-induced vasoconstriction, with cyclooxygenase-2 or L-type calcium channel antagonists. In both acute and chronic mouse models of seizure-induced premature mortality, ibuprofen and nicardipine extended life while systemic drug levels remained high enough to be effective. We also examined the potential role of spreading depolarization in the acute model of seizure-induced premature mortality. These data provide a proof-of-principle for the neurovascular hypothesis of SUDEP rather than spreading depolarization and the use of currently available drugs to prevent it.
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Affiliation(s)
- Antis G George
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Jordan S Farrell
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Neurosurgery, Stanford University, Palo Alto, CA, 94305, USA
| | - Roberto Colangeli
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Department of Experimental and Clinical Medicine, Section of Neuroscience and Cell Biology, Marche Polytechnic University, Ancona, Italy
| | - Alexandra K Wall
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Renaud C Gom
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Mitchell T Kesler
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | | | - Bianca R Villa
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
| | - Tefani Perera
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
| | - Jong M Rho
- Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Neurosciences, Pediatrics and Pharmacology, University of California, San Diego and Rady Children's Hospital, San Diego, CA, USA
| | - Deborah Kurrasch
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Medical Genetics, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - G Campbell Teskey
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada; Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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15
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Yu C, Deng XJ, Xu D. Gene mutations in comorbidity of epilepsy and arrhythmia. J Neurol 2023; 270:1229-1248. [PMID: 36376730 DOI: 10.1007/s00415-022-11430-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 11/16/2022]
Abstract
Epilepsy is one of the most common neurological disorders, and sudden unexpected death in epilepsy (SUDEP) is the most severe outcome of refractory epilepsy. Arrhythmia is one of the heterogeneous factors in the pathophysiological mechanism of SUDEP with a high incidence in patients with refractory epilepsy, increasing the risk of premature death. The gene co-expressed in the brain and heart is supposed to be the genetic basis between epilepsy and arrhythmia, among which the gene encoding ion channel contributes to the prevalence of "cardiocerebral channelopathy" theory. Nevertheless, this theory could only explain the molecular mechanism of comorbid arrhythmia in part of patients with epilepsy (PWE). Therefore, we summarized the mutant genes that can induce comorbidity of epilepsy and arrhythmia and the possible corresponding treatments. These variants involved the genes encoding sodium, potassium, calcium and HCN channels, as well as some non-ion channel coding genes such as CHD4, PKP2, FHF1, GNB5, and mitochondrial genes. The relationship between genotype and clinical phenotype was not simple linear. Indeed, genes co-expressed in the brain and heart could independently induce epilepsy and/or arrhythmia. Mutant genes in brain could affect cardiac rhythm through central or peripheral regulation, while in the heart it could also affect cerebral electrical activity by changing the hemodynamics or internal environment. Analysis of mutations in comorbidity of epilepsy and arrhythmia could refine and expand the theory of "cardiocerebral channelopathy" and provide new insights for risk stratification of premature death and corresponding precision therapy in PWE.
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Affiliation(s)
- Cheng Yu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, Hubei Province, China
| | - Xue-Jun Deng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, Hubei Province, China
| | - Da Xu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, Hubei Province, China.
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16
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Bauer J, Devinsky O, Rothermel M, Koch H. Autonomic dysfunction in epilepsy mouse models with implications for SUDEP research. Front Neurol 2023; 13:1040648. [PMID: 36686527 PMCID: PMC9853197 DOI: 10.3389/fneur.2022.1040648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 12/12/2022] [Indexed: 01/09/2023] Open
Abstract
Epilepsy has a high prevalence and can severely impair quality of life and increase the risk of premature death. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in drug-resistant epilepsy and most often results from respiratory and cardiac impairments due to brainstem dysfunction. Epileptic activity can spread widely, influencing neuronal activity in regions outside the epileptic network. The brainstem controls cardiorespiratory activity and arousal and reciprocally connects to cortical, diencephalic, and spinal cord areas. Epileptic activity can propagate trans-synaptically or via spreading depression (SD) to alter brainstem functions and cause cardiorespiratory dysfunction. The mechanisms by which seizures propagate to or otherwise impair brainstem function and trigger the cascading effects that cause SUDEP are poorly understood. We review insights from mouse models combined with new techniques to understand the pathophysiology of epilepsy and SUDEP. These techniques include in vivo, ex vivo, invasive and non-invasive methods in anesthetized and awake mice. Optogenetics combined with electrophysiological and optical manipulation and recording methods offer unique opportunities to study neuronal mechanisms under normal conditions, during and after non-fatal seizures, and in SUDEP. These combined approaches can advance our understanding of brainstem pathophysiology associated with seizures and SUDEP and may suggest strategies to prevent SUDEP.
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Affiliation(s)
- Jennifer Bauer
- Department of Epileptology and Neurology, RWTH Aachen University, Aachen, Germany,Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Orrin Devinsky
- Departments of Neurology, Neurosurgery and Psychiatry, NYU Langone School of Medicine, New York, NY, United States
| | - Markus Rothermel
- Institute for Physiology and Cell Biology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Henner Koch
- Department of Epileptology and Neurology, RWTH Aachen University, Aachen, Germany,*Correspondence: Henner Koch ✉
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17
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Ortner NJ. CACNA1D-Related Channelopathies: From Hypertension to Autism. Handb Exp Pharmacol 2023. [PMID: 36592224 DOI: 10.1007/164_2022_626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Tightly controlled Ca2+ influx through voltage-gated Ca2+ channels (Cavs) is indispensable for proper physiological function. Thus, it is not surprising that Cav loss and/or gain of function have been implicated in human pathology. Deficiency of Cav1.3 L-type Ca2+ channels (LTCCs) causes deafness and bradycardia, whereas several genetic variants of CACNA1D, the gene encoding the pore-forming α1 subunit of Cav1.3, have been linked to various disease phenotypes, such as hypertension, congenital hypoglycemia, or autism. These variants include not only common polymorphisms associated with an increased disease risk, but also rare de novo missense variants conferring high risk. This review provides a concise summary of disease-associated CACNA1D variants, whereas the main focus lies on de novo germline variants found in individuals with a neurodevelopmental disorder of variable severity. Electrophysiological recordings revealed activity-enhancing gating changes induced by these de novo variants, and tools to predict their pathogenicity and to study the resulting pathophysiological consequences will be discussed. Despite the low number of affected patients, potential phenotype-genotype correlations and factors that could impact the severity of symptoms will be covered. Since increased channel activity is assumed as the disease-underlying mechanism, pharmacological inhibition could be a treatment option. In the absence of Cav1.3-selective blockers, dihydropyridine LTCC inhibitors clinically approved for the treatment of hypertension may be used for personalized off-label trials. Findings from in vitro studies and treatment attempts in some of the patients seem promising as outlined. Taken together, due to advances in diagnostic sequencing techniques the number of reported CACNA1D variants in human diseases is constantly rising. Evidence from in silico, in vitro, and in vivo disease models can help to predict the pathogenic potential of such variants and to guide diagnosis and treatment in the clinical practice when confronted with patients harboring CACNA1D variants.
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Affiliation(s)
- Nadine J Ortner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria.
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18
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Abad-Rodríguez J, Brocca ME, Higuero AM. Glycans and Carbohydrate-Binding/Transforming Proteins in Axon Physiology. ADVANCES IN NEUROBIOLOGY 2023; 29:185-217. [PMID: 36255676 DOI: 10.1007/978-3-031-12390-0_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The mature nervous system relies on the polarized morphology of neurons for a directed flow of information. These highly polarized cells use their somatodendritic domain to receive and integrate input signals while the axon is responsible for the propagation and transmission of the output signal. However, the axon must perform different functions throughout development before being fully functional for the transmission of information in the form of electrical signals. During the development of the nervous system, axons perform environmental sensing functions, which allow them to navigate through other regions until a final target is reached. Some axons must also establish a regulated contact with other cells before reaching maturity, such as with myelinating glial cells in the case of myelinated axons. Mature axons must then acquire the structural and functional characteristics that allow them to perform their role as part of the information processing and transmitting unit that is the neuron. Finally, in the event of an injury to the nervous system, damaged axons must try to reacquire some of their immature characteristics in a regeneration attempt, which is mostly successful in the PNS but fails in the CNS. Throughout all these steps, glycans perform functions of the outermost importance. Glycans expressed by the axon, as well as by their surrounding environment and contacting cells, encode key information, which is fine-tuned by glycan modifying enzymes and decoded by glycan binding proteins so that the development, guidance, myelination, and electrical transmission functions can be reliably performed. In this chapter, we will provide illustrative examples of how glycans and their binding/transforming proteins code and decode instructive information necessary for fundamental processes in axon physiology.
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Affiliation(s)
- José Abad-Rodríguez
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain.
| | - María Elvira Brocca
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
| | - Alonso Miguel Higuero
- Membrane Biology and Axonal Repair Laboratory, Hospital Nacional de Parapléjicos (SESCAM), Toledo, Spain
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19
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Aloi MS, Thompson SJ, Quartapella N, Noebels JL. Loss of functional System x-c uncouples aberrant postnatal neurogenesis from epileptogenesis in the hippocampus of Kcna1-KO mice. Cell Rep 2022; 41:111696. [PMID: 36417872 PMCID: PMC9753929 DOI: 10.1016/j.celrep.2022.111696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 09/29/2022] [Accepted: 10/28/2022] [Indexed: 11/23/2022] Open
Abstract
Mutations in Kv1.1 (Kcna1) voltage-gated potassium channels in humans and mice generate network hyperexcitability, enhancing aberrant postnatal neurogenesis in the dentate subgranular zone, resulting in epilepsy and hippocampal hypertrophy. While Kcna1 loss stimulates proliferation of progenitor cell subpopulations, the identity of extrinsic molecular triggers linking network hyperexcitability to aberrant postnatal neurogenesis remains incomplete. System x-c (Sxc) is an inducible glutamate/cysteine antiporter that regulates extracellular glutamate. Here, we find that the functional unit of Sxc, xCT (Slc7a11), is upregulated in regions of Kcna1 knockout (KO) hippocampus, suggesting a contribution to both hyperplasia and epilepsy. However, Slc7a11 KO suppressed and rescued hippocampal enlargement without altering seizure severity in Kcna1-Slc7a11-KO mice. Microglial activation, but not astrocytosis, was also reduced. Our study identifies Sxc-mediated glutamate homeostasis as an essential non-synaptic trigger coupling aberrant postnatal neurogenesis and neuroimmune crosstalk, revealing that neurogenesis and epileptogenesis in the dentate gyrus are not mutually contingent events.
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Affiliation(s)
- Macarena S Aloi
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA; Blue Bird Circle Developmental Neurogenetics Laboratory, Houston, TX, USA
| | - Samantha J Thompson
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA; Blue Bird Circle Developmental Neurogenetics Laboratory, Houston, TX, USA
| | - Nicholas Quartapella
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA; Blue Bird Circle Developmental Neurogenetics Laboratory, Houston, TX, USA; Department of BioSciences, Rice University, Houston, TX, USA
| | - Jeffrey L Noebels
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA; Blue Bird Circle Developmental Neurogenetics Laboratory, Houston, TX, USA.
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20
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Kreitlow BL, Li W, Buchanan GF. Chronobiology of epilepsy and sudden unexpected death in epilepsy. Front Neurosci 2022; 16:936104. [PMID: 36161152 PMCID: PMC9490261 DOI: 10.3389/fnins.2022.936104] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 06/27/2022] [Indexed: 11/24/2022] Open
Abstract
Epilepsy is a neurological disease characterized by spontaneous, unprovoked seizures. Various insults render the brain hyperexcitable and susceptible to seizure. Despite there being dozens of preventative anti-seizure medications available, these drugs fail to control seizures in nearly 1 in 3 patients with epilepsy. Over the last century, a large body of evidence has demonstrated that internal and external rhythms can modify seizure phenotypes. Physiologically relevant rhythms with shorter periodic rhythms, such as endogenous circadian rhythms and sleep-state, as well as rhythms with longer periodicity, including multidien rhythms and menses, influence the timing of seizures through poorly understood mechanisms. The purpose of this review is to discuss the findings from both human and animal studies that consider the effect of such biologically relevant rhythms on epilepsy and seizure-associated death. Patients with medically refractory epilepsy are at increased risk of sudden unexpected death in epilepsy (SUDEP). The role that some of these rhythms play in the nocturnal susceptibility to SUDEP will also be discussed. While the involvement of some of these rhythms in epilepsy has been known for over a century, applying the rhythmic nature of such phenomenon to epilepsy management, particularly in mitigating the risk of SUDEP, has been underutilized. As our understanding of the physiological influence on such rhythmic phenomenon improves, and as technology for chronic intracranial epileptiform monitoring becomes more widespread, smaller and less invasive, novel seizure-prediction technologies and time-dependent chronotherapeutic seizure management strategies can be realized.
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Affiliation(s)
- Benjamin L. Kreitlow
- Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
- Department of Neurology, University of Iowa, Iowa City, IA, United States
- Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - William Li
- Department of Neurology, University of Iowa, Iowa City, IA, United States
- Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Gordon F. Buchanan
- Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA, United States
- Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, United States
- Department of Neurology, University of Iowa, Iowa City, IA, United States
- Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- *Correspondence: Gordon F. Buchanan, ; orcid.org/0000-0003-2371-4455
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21
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Dinoi G, Morin M, Conte E, Mor Shaked H, Coppola MA, D’Adamo MC, Elpeleg O, Liantonio A, Hartmann I, De Luca A, Blunck R, Russo A, Imbrici P. Clinical and Functional Study of a De Novo Variant in the PVP Motif of Kv1.1 Channel Associated with Epilepsy, Developmental Delay and Ataxia. Int J Mol Sci 2022; 23:ijms23158079. [PMID: 35897654 PMCID: PMC9331732 DOI: 10.3390/ijms23158079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 02/05/2023] Open
Abstract
Mutations in the KCNA1 gene, encoding the voltage-gated potassium channel Kv1.1, have been associated with a spectrum of neurological phenotypes, including episodic ataxia type 1 and developmental and epileptic encephalopathy. We have recently identified a de novo variant in KCNA1 in the highly conserved Pro-Val-Pro motif within the pore of the Kv1.1 channel in a girl affected by early onset epilepsy, ataxia and developmental delay. Other mutations causing severe epilepsy are located in Kv1.1 pore domain. The patient was initially treated with a combination of antiepileptic drugs with limited benefit. Finally, seizures and ataxia control were achieved with lacosamide and acetazolamide. The aim of this study was to functionally characterize Kv1.1 mutant channel to provide a genotype–phenotype correlation and discuss therapeutic options for KCNA1-related epilepsy. To this aim, we transfected HEK 293 cells with Kv1.1 or P403A cDNAs and recorded potassium currents through whole-cell patch-clamp. P403A channels showed smaller potassium currents, voltage-dependent activation shifted by +30 mV towards positive potentials and slower kinetics of activation compared with Kv1.1 wild-type. Heteromeric Kv1.1+P403A channels, resembling the condition of the heterozygous patient, confirmed a loss-of-function biophysical phenotype. Overall, the functional characterization of P403A channels correlates with the clinical symptoms of the patient and supports the observation that mutations associated with severe epileptic phenotype cluster in a highly conserved stretch of residues in Kv1.1 pore domain. This study also strengthens the beneficial effect of acetazolamide and sodium channel blockers in KCNA1 channelopathies.
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Affiliation(s)
- Giorgia Dinoi
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.D.); (E.C.); (M.A.C.); (A.L.); (A.D.L.)
| | - Michael Morin
- Department of Physics, Université de Montréal, Montreal, QC H3C 3J7, Canada; (M.M.); (R.B.)
- CIRCA, Center for Interdisciplinary Research on Brain and Learning, Université de Montréal, Montreal, QC H3C 3J7, Canada
| | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.D.); (E.C.); (M.A.C.); (A.L.); (A.D.L.)
| | - Hagar Mor Shaked
- Department of Genetics, Hadassah Medical Center, Jerusalem 91120, Israel; (H.M.S.); (O.E.)
| | - Maria Antonietta Coppola
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.D.); (E.C.); (M.A.C.); (A.L.); (A.D.L.)
| | | | - Orly Elpeleg
- Department of Genetics, Hadassah Medical Center, Jerusalem 91120, Israel; (H.M.S.); (O.E.)
| | - Antonella Liantonio
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.D.); (E.C.); (M.A.C.); (A.L.); (A.D.L.)
| | - Inbar Hartmann
- Pediatric Neurology Clinic, Shamir Medical Center (Assaf Harofeh), Zerifin 7033001, Israel;
| | - Annamaria De Luca
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.D.); (E.C.); (M.A.C.); (A.L.); (A.D.L.)
| | - Rikard Blunck
- Department of Physics, Université de Montréal, Montreal, QC H3C 3J7, Canada; (M.M.); (R.B.)
- CIRCA, Center for Interdisciplinary Research on Brain and Learning, Université de Montréal, Montreal, QC H3C 3J7, Canada
- Department of Pharmacology and Physiology, Université de Montréal, Montreal, QC H3C 3J7, Canada
| | - Angelo Russo
- Child Neurology Unit, IRCCS, Institute of Neurological Sciences of Bologna, 40139 Bologna, Italy;
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy; (G.D.); (E.C.); (M.A.C.); (A.L.); (A.D.L.)
- Correspondence:
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22
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Yee JX, Rastani A, Soden ME. The potassium channel auxiliary subunit Kvβ2 ( Kcnab2) regulates Kv1 channels and dopamine neuron firing. J Neurophysiol 2022; 128:62-72. [PMID: 35788155 PMCID: PMC9273274 DOI: 10.1152/jn.00194.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ion channel complexes typically consist of both pore-forming subunits and auxiliary subunits that do not directly conduct current but can regulate trafficking or alter channel properties. Isolating the role of these auxiliary subunits in neurons has proved difficult due to a lack of specific pharmacological agents and the potential for developmental compensation in constitutive knockout models. Here, we use cell-type-specific viral-mediated CRISPR/Cas9 mutagenesis to target the potassium channel auxiliary subunit Kvβ2 (Kcnab2) in dopamine neurons in the adult mouse brain. We find that mutagenesis of Kcnab2 reduces surface expression of Kv1.2, the primary Kv1 pore-forming subunit expressed in dopamine neurons, and shifts the voltage dependence of inactivation of potassium channel currents toward more hyperpolarized potentials. Loss of Kcnab2 broadens the action potential waveform in spontaneously firing dopamine neurons recorded in slice, reduces the afterhyperpolarization amplitude, and increases spike timing irregularity and excitability, all of which is consistent with a reduction in potassium channel current. Similar effects were observed with mutagenesis of the pore-forming subunit Kv1.2 (Kcna2). These results identify Kv1 currents as important contributors to dopamine neuron firing and demonstrate a role for Kvβ2 subunits in regulating the trafficking and gating properties of these ion channels. Furthermore, they demonstrate the utility of CRISPR-mediated mutagenesis in the study of previously difficult to isolate ion channel subunits.NEW & NOTEWORTHY Here, we utilize CRISPR/Cas9-mediated mutagenesis in dopamine neurons in mice to target the gene encoding Kvβ2, an auxiliary subunit that forms a part of Kv1 channel complexes. We find that the absence of Kvβ2 alters action potential properties by reducing surface expression of pore-forming subunits and shifting the voltage dependence of channel inactivation. This work establishes a new function for Kvβ2 subunits and Kv1 complexes in regulating dopamine neuron activity.
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Affiliation(s)
- Joshua X. Yee
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Ariana Rastani
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Marta E. Soden
- Department of Pharmacology, University of Washington, Seattle, Washington
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23
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K v1.1 preserves the neural stem cell pool and facilitates neuron maturation during adult hippocampal neurogenesis. Proc Natl Acad Sci U S A 2022; 119:e2118240119. [PMID: 35613055 PMCID: PMC9295736 DOI: 10.1073/pnas.2118240119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Despite decades of research on adult neurogenesis, little is known about the role of bioelectric signaling in this process. In this study, we describe how a voltage-gated potassium channel, Kv1.1, supports adult neurogenesis by maintaining the neural stem cell niche and facilitating newborn neuron development. Additionally, we show that deletion of Kv1.1 from adult neural stem cells contributes to modest impairments in hippocampus-dependent contextual fear learning and memory. Dysfunctional adult neurogenesis has been implicated in cognitive decline associated with aging and neurological disease. Therefore, understanding the role of Kv1.1 in adult neurogenesis represents an opportunity to identify new therapeutic targets to promote healthy neurogenesis and cognition. Adult hippocampal neurogenesis is critical for learning and memory, and aberrant adult neurogenesis has been implicated in cognitive decline associated with aging and neurological diseases [J. T. Gonçalves, S. T. Schafer, F. H. Gage, Cell 167, 897–914 (2016)]. In previous studies, we observed that the delayed-rectifier voltage-gated potassium channel Kv1.1 controls the membrane potential of neural stem and progenitor cells and acts as a brake on neurogenesis during neonatal hippocampal development [S. M. Chou et al., eLife 10, e58779 (2021)]. To assess the role of Kv1.1 in adult hippocampal neurogenesis, we developed an inducible conditional knockout mouse to specifically remove Kv1.1 from adult neural stem cells via tamoxifen administration. We determined that Kv1.1 deletion in adult neural stem cells causes overproliferation and depletion of radial glia-like neural stem cells, prevents proper adult-born granule cell maturation and integration into the dentate gyrus, and moderately impairs hippocampus-dependent contextual fear learning and memory. Taken together, these findings support a critical role for this voltage-gated ion channel in adult neurogenesis.
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24
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Sun H, Patil MJ, Ru F, Meeker S, Undem BJ. K
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1/D‐type potassium channels inhibit the excitability of bronchopulmonary vagal afferent nerves. J Physiol 2022; 600:2953-2971. [PMID: 35430729 PMCID: PMC9203938 DOI: 10.1113/jp282803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 04/04/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract The KV1/D‐type potassium current (ID) is an important determinant of neuronal excitability. This study explored whether and how ID channels regulate the activation of bronchopulmonary vagal afferent nerves. The single‐neuron RT‐PCR assay revealed that nearly all mouse bronchopulmonary nodose neurons expressed the transcripts of α‐dendrotoxin (α‐DTX)‐sensitive, ID channel‐forming KV1.1, KV1.2 and/or KV1.6 α‐subunits, with the expression of KV1.6 being most prevalent. Patch‐clamp recordings showed that ID, defined as the α‐DTX‐sensitive K+ current, activated at voltages slightly more negative than the resting membrane potential in lung‐specific nodose neurons and displayed little inactivation at subthreshold voltages. Inhibition of ID channels by α‐DTX depolarized the lung‐specific nodose neurons and caused an increase in input resistance, decrease in rheobase, as well as increase in action potential number and firing frequency in response to suprathreshold current steps. Application of α‐DTX to the lungs via trachea in the mouse ex vivo vagally innervated trachea–lungs preparation led to action potential discharges in nearly half of bronchopulmonary nodose afferent nerve fibres, including nodose C‐fibres, as detected by the two‐photon microscopic Ca2+ imaging technique and extracellular electrophysiological recordings. In conclusion, ID channels act as a critical brake on the activation of bronchopulmonary vagal afferent nerves by stabilizing the membrane potential, counterbalancing the subthreshold depolarization and promoting the adaptation of action potential firings. Down‐regulation of ID channels, as occurs in various inflammatory diseases, may contribute to the enhanced C‐fibre activity in airway diseases that are associated with excessive coughing, dyspnoea, and reflex bronchospasm and secretions. Key points The α‐dendrotoxin (α‐DTX)‐sensitive D‐type K+ current (ID) is an important determinant of neuronal excitability. Nearly all bronchopulmonary nodose afferent neurons in the mouse express ID and the transcripts of α‐DTX‐sensitive, ID channel‐forming KV1.1, KV1.2 and/or KV1.6 α‐subunits. Inhibition of ID channels by α‐DTX depolarizes the bronchopulmonary nodose neurons, reduces the minimal depolarizing current needed to evoke an action potential (AP) and increases AP number and AP firing frequency in response to suprathreshold stimulations. Application of α‐DTX to the lungs ex vivo elicits AP discharges in about half of bronchopulmonary nodose C‐fibre terminals.
Our novel finding that ID channels act as a critical brake on the activation of bronchopulmonary vagal afferent nerves suggests that their down‐regulation, as occurs in various inflammatory diseases, may contribute to the enhanced C‐fibre activity in airway inflammation associated with excessive respiratory symptoms.
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Affiliation(s)
- Hui Sun
- Division of Allergy and Clinical Immunology Department of Medicine Johns Hopkins University School of Medicine 5501 Hopkins Bayview Circle Baltimore 21224
| | - Mayur J. Patil
- Division of Allergy and Clinical Immunology Department of Medicine Johns Hopkins University School of Medicine 5501 Hopkins Bayview Circle Baltimore 21224
| | - Fei Ru
- Division of Allergy and Clinical Immunology Department of Medicine Johns Hopkins University School of Medicine 5501 Hopkins Bayview Circle Baltimore 21224
| | - Sonya Meeker
- Division of Allergy and Clinical Immunology Department of Medicine Johns Hopkins University School of Medicine 5501 Hopkins Bayview Circle Baltimore 21224
| | - Bradley J. Undem
- Division of Allergy and Clinical Immunology Department of Medicine Johns Hopkins University School of Medicine 5501 Hopkins Bayview Circle Baltimore 21224
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25
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Genetic paroxysmal neurological disorders featuring episodic ataxia and epilepsy. Eur J Med Genet 2022; 65:104450. [DOI: 10.1016/j.ejmg.2022.104450] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 02/02/2022] [Accepted: 02/06/2022] [Indexed: 01/25/2023]
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26
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Teran FA, Bravo E, Richerson GB. Sudden unexpected death in epilepsy: Respiratory mechanisms. HANDBOOK OF CLINICAL NEUROLOGY 2022; 189:153-176. [PMID: 36031303 PMCID: PMC10191258 DOI: 10.1016/b978-0-323-91532-8.00012-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Epilepsy is one of the most common chronic neurologic diseases, with a prevalence of 1% in the US population. Many people with epilepsy live normal lives, but are at risk of sudden unexpected death in epilepsy (SUDEP). This mysterious comorbidity of epilepsy causes premature death in 17%-50% of those with epilepsy. Most SUDEP occurs after a generalized seizure, and patients are typically found in bed in the prone position. Until recently, it was thought that SUDEP was due to cardiovascular failure, but patients who died while being monitored in hospital epilepsy units revealed that most SUDEP is due to postictal central apnea. Some cases may occur when seizures invade the amygdala and activate projections to the brainstem. Evidence suggests that the pathophysiology is linked to defects in the serotonin system and central CO2 chemoreception, and that there is considerable overlap with mechanisms thought to be involved in sudden infant death syndrome (SIDS). Future work is needed to identify biomarkers for patients at highest risk, improve ascertainment, develop methods to alert caregivers when SUDEP is imminent, and find effective approaches to prevent these fatal events.
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Affiliation(s)
- Frida A Teran
- Department of Neurology, University of Iowa, Iowa City, IA, United States; Medical Scientist Training Program, University of Iowa, Iowa City, IA, United States.
| | - Eduardo Bravo
- Department of Neurology, University of Iowa, Iowa City, IA, United States
| | - George B Richerson
- Department of Neurology, University of Iowa, Iowa City, IA, United States; Department of Molecular Physiology & Biophysics, University of Iowa, Iowa City, IA, United States
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27
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Baudin P, Cousyn L, Navarro V. The LGI1 protein: molecular structure, physiological functions and disruption-related seizures. Cell Mol Life Sci 2021; 79:16. [PMID: 34967933 PMCID: PMC11072701 DOI: 10.1007/s00018-021-04088-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/07/2021] [Accepted: 12/09/2021] [Indexed: 01/16/2023]
Abstract
Leucine-rich, glioma inactivated 1 (LGI1) is a secreted glycoprotein, mainly expressed in the brain, and involved in central nervous system development and physiology. Mutations of LGI1 have been linked to autosomal dominant lateral temporal lobe epilepsy (ADLTE). Recently auto-antibodies against LGI1 have been described as the basis for an autoimmune encephalitis, associated with specific motor and limbic epileptic seizures. It is the second most common cause of autoimmune encephalitis. This review presents details on the molecular structure, expression and physiological functions of LGI1, and examines how their disruption underlies human pathologies. Knock-down of LGI1 in rodents reveals that this protein is necessary for normal brain development. In mature brains, LGI1 is associated with Kv1 channels and AMPA receptors, via domain-specific interaction with membrane anchoring proteins and contributes to regulation of the expression and function of these channels. Loss of function, due to mutations or autoantibodies, of this key protein in the control of neuronal activity is a common feature in the genesis of epileptic seizures in ADLTE and anti-LGI1 autoimmune encephalitis.
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Affiliation(s)
- Paul Baudin
- Sorbonne Université, Paris Brain Institute - Institut du Cerveau, ICM, INSERM, CNRS, AP-HP, Pitié-Salpêtrière Hospital, Paris, France
| | - Louis Cousyn
- Sorbonne Université, Paris Brain Institute - Institut du Cerveau, ICM, INSERM, CNRS, AP-HP, Pitié-Salpêtrière Hospital, Paris, France
- AP-HP, Epilepsy Unit, Pitié-Salpêtrière Hospital, DMU Neurosciences, Paris, France
| | - Vincent Navarro
- Sorbonne Université, Paris Brain Institute - Institut du Cerveau, ICM, INSERM, CNRS, AP-HP, Pitié-Salpêtrière Hospital, Paris, France.
- AP-HP, Epilepsy Unit, Pitié-Salpêtrière Hospital, DMU Neurosciences, Paris, France.
- AP-HP, Center of Reference for Rare Epilepsies, Pitié-Salpêtrière Hospital, 47-83 Boulevard de l'Hôpital, 75013, Paris, France.
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28
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Deodhar M, Matthews SA, Thomas B, Adamian L, Mattes S, Wells T, Zieba B, Simeone KA, Simeone TA. Pharmacoresponsiveness of spontaneous recurrent seizures and the comorbid sleep disorder of epileptic Kcna1-null mice. Eur J Pharmacol 2021; 913:174656. [PMID: 34838797 DOI: 10.1016/j.ejphar.2021.174656] [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: 08/18/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 11/24/2022]
Abstract
Drug resistant epilepsy affects ∼30% of people with epilepsy and is associated with epilepsy syndromes with frequent and multiple types of seizures, lesions or cytoarchitectural abnormalities, increased risk of mortality and comorbidities such as cognitive impairment and sleep disorders. A limitation of current preclinical models is that spontaneous seizures with comorbidities take time to induce and test, thus making them low-throughput. Kcna1-null mice exhibit all the characteristics of drug resistant epilepsy with spontaneous seizures and comorbidities occurring naturally; thus, we aimed to determine whether they also demonstrate pharmacoresistanct seizures and the impact of medications on their sleep disorder comorbidity. In this exploratory study, Kcna1-null mice were treated with one of four conventional antiseizure medications, carbamazepine, levetiracetam, phenytoin, and phenobarbital using a moderate throughput protocol (vehicle for 2 days followed by 2 days of treatment with high therapeutic doses selected based on published data in the 6 Hz model of pharmacoresistant seizures). Spontaneous recurrent seizures and vigilance states were recorded with video-EEG/EMG. Carbamazepine, levetiracetam and phenytoin had partial efficacy (67%, 75% and 33% were seizure free, respectively), whereas phenobarbital was fully efficacious and conferred seizure freedom to all mice. Thus, seizures of Kcna1-null mice appear to be resistant to three of the drugs tested. Levetiracetam failed to affect sleep architecture, carbamazepine and phenytoin had moderate effects, and phenobarbital, as predicted, restored sleep architecture. Data suggest Kcna1-null mice may be a moderate throughput model of drug resistant epilepsy useful in determining mechanisms of pharmacoresistance and testing novel therapeutic strategies.
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Affiliation(s)
- Malavika Deodhar
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Stephanie A Matthews
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Brittany Thomas
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Leena Adamian
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Sarah Mattes
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Tabitha Wells
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Brianna Zieba
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Kristina A Simeone
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Timothy A Simeone
- Department of Pharmacology & Neuroscience, Creighton University School of Medicine, Omaha, NE, USA.
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29
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Hu P, Wu D, Zang YY, Wang Y, Zhou YP, Qiao F, Teng XY, Chen J, Li QQ, Sun JH, Liu T, Feng HY, Zhou QG, Shi YS, Xu Z. A novel LGI1 mutation causing autosomal dominant lateral temporal lobe epilepsy confirmed by a precise knock-in mouse model. CNS Neurosci Ther 2021; 28:237-246. [PMID: 34767694 PMCID: PMC8739050 DOI: 10.1111/cns.13761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 10/20/2021] [Accepted: 10/25/2021] [Indexed: 12/30/2022] Open
Abstract
AIMS This study aimed to explore the pathomechanism of a mutation on the leucine-rich glioma inactivated 1 gene (LGI1) identified in a family having autosomal dominant lateral temporal lobe epilepsy (ADLTE), using a precise knock-in mouse model. METHODS AND RESULTS A novel LGI1 mutation, c.152A>G; p. Asp51Gly, was identified by whole exome sequencing in a Chinese family with ADLTE. The pathomechanism of the mutation was explored by generating Lgi1D51G knock-in mice that precisely phenocopied the epileptic symptoms of human patients. The Lgi1D51G / D51G mice showed spontaneous recurrent generalized seizures and premature death. The Lgi1D51G /+ mice had partial epilepsy, with half of them displaying epileptiform discharges on electroencephalography. They also showed enhanced sensitivity to the convulsant agent pentylenetetrazole. Mechanistically, the secretion of Lgi1 was impaired in the brain of the D51G knock-in mice and the protein level was drastically reduced. Moreover, the antiepileptic drugs, carbamazepine, oxcarbazepine, and sodium valproate, could prolong the survival time of Lgi1D51G / D51G mice, and oxcarbazepine appeared to be the most effective. CONCLUSIONS We identified a novel epilepsy-causing mutation of LGI1 in humans. The Lgi1D51G /+ mouse model, precisely phenocopying epileptic symptoms of human patients, could be a useful tool in future studies on the pathogenesis and potential therapies for epilepsy.
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Affiliation(s)
- Ping Hu
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health care Hospital, Nanjing, China
| | - Dan Wu
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - Yan-Yu Zang
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - Yan Wang
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health care Hospital, Nanjing, China
| | - Ya-Ping Zhou
- School of Pharmacy, Nanjing Medical University, Nanjing, China
| | - Fengchang Qiao
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health care Hospital, Nanjing, China
| | - Xiao-Yu Teng
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - Jiang Chen
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - Qing-Qing Li
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - Jia-Hui Sun
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - TingTing Liu
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - Hao-Yang Feng
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health care Hospital, Nanjing, China
| | - Qi-Gang Zhou
- School of Pharmacy, Nanjing Medical University, Nanjing, China
| | - Yun Stone Shi
- Minister of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Department of Neurology, Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.,State Key Laboratory of Pharmaceutical Biotechnology, National Resource for Mutant Mice, Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China.,Chemistry and Biomedicine Innovation Center, Nanjing University, Nanjing, China.,Institute for Brain Sciences, Nanjing University, Nanjing, China
| | - Zhengfeng Xu
- Department of Prenatal Diagnosis, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health care Hospital, Nanjing, China
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30
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Studying Independent Kcna6 Knock-out Mice Reveals Toxicity of Exogenous LacZ to Central Nociceptor Terminals and Differential Effects of Kv1.6 on Acute and Neuropathic Pain Sensation. J Neurosci 2021; 41:9141-9162. [PMID: 34544832 DOI: 10.1523/jneurosci.0187-21.2021] [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: 01/25/2021] [Revised: 08/19/2021] [Accepted: 08/20/2021] [Indexed: 11/21/2022] Open
Abstract
The potassium channel Kv1.6 has recently been implicated as a major modulatory channel subunit expressed in primary nociceptors. Furthermore, its expression at juxtaparanodes of myelinated primary afferents is induced following traumatic nerve injury as part of an endogenous mechanism to reduce hyperexcitability and pain-related hypersensitivity. In this study, we compared two mouse models of constitutive Kv1.6 knock-out (KO) achieved by different methods: traditional gene trap via homologous recombination and CRISPR-mediated excision. Both Kv1.6 KO mouse lines exhibited an unexpected reduction in sensitivity to noxious heat stimuli, to differing extents: the Kv1.6 mice produced via gene trap had a far more significant hyposensitivity. These mice (Kcna6lacZ ) expressed the bacterial reporter enzyme LacZ in place of Kv1.6 as a result of the gene trap mechanism, and we found that their central primary afferent presynaptic terminals developed a striking neurodegenerative phenotype involving accumulation of lipid species, development of "meganeurites," and impaired transmission to dorsal horn wide dynamic range neurons. The anatomic defects were absent in CRISPR-mediated Kv1.6 KO mice (Kcna6 -/-) but were present in a third mouse model expressing exogenous LacZ in nociceptors under the control of a Nav1.8-promoted Cre recombinase. LacZ reporter enzymes are thus intrinsically neurotoxic to sensory neurons and may induce pathologic defects in transgenic mice, which has confounding implications for the interpretation of gene KOs using lacZ Nonetheless, in Kcna6 -/- mice not affected by LacZ, we demonstrated a significant role for Kv1.6 regulating acute noxious thermal sensitivity, and both mechanical and thermal pain-related hypersensitivity after nerve injury.SIGNIFICANCE STATEMENT In recent decades, the expansion of technologies to experimentally manipulate the rodent genome has contributed significantly to the field of neuroscience. While introduction of enzymatic or fluorescent reporter proteins to label neuronal populations is now commonplace, often potential toxicity effects are not fully considered. We show a role of Kv1.6 in acute and neuropathic pain states through analysis of two mouse models lacking Kv1.6 potassium channels: one with additional expression of LacZ and one without. We show that LacZ reporter enzymes induce unintended defects in sensory neurons, with an impact on behavioral data outcomes. To summarize we highlight the importance of Kv1.6 in recovery of normal sensory function following nerve injury, and careful interpretation of data from LacZ reporter models.
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31
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Konduru SS, Pan YZ, Wallace E, Pfammatter JA, Jones MV, Maganti RK. Sleep Deprivation Exacerbates Seizures and Diminishes GABAergic Tonic Inhibition. Ann Neurol 2021; 90:840-844. [PMID: 34476841 PMCID: PMC8530964 DOI: 10.1002/ana.26208] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 08/31/2021] [Accepted: 08/31/2021] [Indexed: 12/31/2022]
Abstract
Patients with epilepsy report that sleep deprivation is a common trigger for breakthrough seizures. The basic mechanism of this phenomenon is unknown. In the Kv1.1-/- mouse model of epilepsy, daily sleep deprivation indeed exacerbated seizures though these effects were lost after the third day. Sleep deprivation also accelerated mortality in ~ 52% of Kv1.1-/- mice, not observed in controls. Voltage-clamp experiments on the day after recovery from sleep deprivation showed reductions in GABAergic tonic inhibition in dentate granule cells in epileptic Kv1.1-/- mice. Our results suggest that sleep deprivation is detrimental to seizures and survival, possibly due to reductions in GABAergic tonic inhibition. ANN NEUROL 2021;90:840-844.
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Affiliation(s)
- Sai Surthi Konduru
- Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Yu-Zhen Pan
- Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Eli Wallace
- Department of Cellular and Molecular Pathology, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Jesse A Pfammatter
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Mathew V Jones
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Rama K Maganti
- Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI
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32
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Yang YS, Choi JH, Rah JC. Hypoxia with inflammation and reperfusion alters membrane resistance by dynamically regulating voltage-gated potassium channels in hippocampal CA1 neurons. Mol Brain 2021; 14:147. [PMID: 34556177 PMCID: PMC8461870 DOI: 10.1186/s13041-021-00857-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/07/2021] [Indexed: 02/01/2023] Open
Abstract
Hypoxia typically accompanies acute inflammatory responses in patients and animal models. However, a limited number of studies have examined the effect of hypoxia in combination with inflammation (Hypo-Inf) on neural function. We previously reported that neuronal excitability in hippocampal CA1 neurons decreased during hypoxia and greatly rebounded upon reoxygenation. We attributed this altered excitability mainly to the dynamic regulation of hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels and input resistance. However, the molecular mechanisms underlying input resistance changes by Hypo-Inf and reperfusion remained unclear. In the present study, we found that a change in the density of the delayed rectifier potassium current (IDR) can explain the input resistance variability. Furthermore, voltage-dependent inactivation of A-type potassium (IA) channels shifted in the depolarizing direction during Hypo-Inf and reverted to normal upon reperfusion without a significant alteration in the maximum current density. Our results indicate that changes in the input resistance, and consequently excitability, caused by Hypo-Inf and reperfusion are at least partially regulated by the availability and voltage dependence of KV channels. Moreover, these results suggest that selective KV channel modulators can be used as potential neuroprotective drugs to minimize hypoxia- and reperfusion-induced neuronal damage.
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Affiliation(s)
- Yoon-Sil Yang
- Korea Brain Research Institute, 61 Cheomdan-ro, Dong-gu, Daegu, 41062 South Korea
| | - Joon Ho Choi
- Korea Brain Research Institute, 61 Cheomdan-ro, Dong-gu, Daegu, 41062 South Korea
| | - Jong-Cheol Rah
- Korea Brain Research Institute, 61 Cheomdan-ro, Dong-gu, Daegu, 41062 South Korea
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, 333 Techno Jungang-daero, Dalseong-gun, Daegu, 42988 South Korea
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33
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A Novel KCNA2 Variant in a Patient with Non-Progressive Congenital Ataxia and Epilepsy: Functional Characterization and Sensitivity to 4-Aminopyridine. Int J Mol Sci 2021; 22:ijms22189913. [PMID: 34576077 PMCID: PMC8469797 DOI: 10.3390/ijms22189913] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/02/2021] [Accepted: 09/08/2021] [Indexed: 12/26/2022] Open
Abstract
Kv1.2 channels, encoded by the KCNA2 gene, are localized in the central and peripheral nervous system, where they regulate neuronal excitability. Recently, heterozygous mutations in KCNA2 have been associated with a spectrum of symptoms extending from epileptic encephalopathy, intellectual disability, and cerebellar ataxia. Patients are treated with a combination of antiepileptic drugs and 4-aminopyridine (4-AP) has been recently trialed in specific cases. We identified a novel variant in KCNA2, E236K, in a Serbian proband with non-progressive congenital ataxia and early onset epilepsy, treated with sodium valproate. To ascertain the pathogenicity of E236K mutation and to verify its sensitivity to 4-AP, we transfected HEK 293 cells with Kv1.2 WT or E236K cDNAs and recorded potassium currents through the whole-cell patch-clamp. In silico analysis supported the electrophysiological data. E236K channels showed voltage-dependent activation shifted towards negative potentials and slower kinetics of deactivation and activation compared with Kv1.2 WT. Heteromeric Kv1.2 WT+E236K channels, resembling the condition of the heterozygous patient, confirmed a mixed gain- and loss-of-function (GoF/LoF) biophysical phenotype. 4-AP inhibited both Kv1.2 and E236K channels with similar potency. Homology modeling studies of mutant channels suggested a reduced interaction between the residue K236 in the S2 segment and the gating charges at S4. Overall, the biophysical phenotype of E236K channels correlates with the mild end of the clinical spectrum reported in patients with GoF/LoF defects. The response to 4-AP corroborates existing evidence that KCNA2-disorders could benefit from variant-tailored therapeutic approaches, based on functional studies.
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34
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Carstens KE, Lustberg DJ, Shaughnessy EK, McCann KE, Alexander GM, Dudek SM. Perineuronal net degradation rescues CA2 plasticity in a mouse model of Rett syndrome. J Clin Invest 2021; 131:e137221. [PMID: 34228646 DOI: 10.1172/jci137221] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 06/25/2021] [Indexed: 12/14/2022] Open
Abstract
Perineuronal nets (PNNs), a specialized form of extracellular matrix, are abnormal in the brains of people with Rett syndrome (RTT). We previously reported that PNNs function to restrict synaptic plasticity in hippocampal area CA2, which is unusually resistant to long-term potentiation (LTP) and has been linked to social learning in mice. Here we report that PNNs appear elevated in area CA2 of the hippocampus of an individual with RTT and that PNNs develop precociously and remain elevated in area CA2 of a mouse model of RTT (Mecp2-null). Further, we provide evidence that LTP could be induced at CA2 synapses prior to PNN maturation (postnatal day 8-11) in wild-type mice and that this window of plasticity was prematurely restricted at CA2 synapses in Mecp2-null mice. Degrading PNNs in Mecp2-null hippocampus was sufficient to rescue the premature disruption of CA2 plasticity. We identified several molecular targets that were altered in the developing Mecp2-null hippocampus that may explain aberrant PNNs and CA2 plasticity, and we discovered that CA2 PNNs are negatively regulated by neuronal activity. Collectively, our findings demonstrate that CA2 PNN development is regulated by Mecp2 and identify a window of hippocampal plasticity that is disrupted in a mouse model of RTT.
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35
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Fukata Y, Hirano Y, Miyazaki Y, Yokoi N, Fukata M. Trans-synaptic LGI1–ADAM22–MAGUK in AMPA and NMDA receptor regulation. Neuropharmacology 2021; 194:108628. [DOI: 10.1016/j.neuropharm.2021.108628] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 05/16/2021] [Accepted: 05/18/2021] [Indexed: 02/06/2023]
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36
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K v1.1 channels mediate network excitability and feed-forward inhibition in local amygdala circuits. Sci Rep 2021; 11:15180. [PMID: 34312446 PMCID: PMC8313690 DOI: 10.1038/s41598-021-94633-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 07/14/2021] [Indexed: 01/15/2023] Open
Abstract
Kv1.1 containing potassium channels play crucial roles towards dampening neuronal excitability. Mice lacking Kv1.1 subunits (Kcna1−/−) display recurrent spontaneous seizures and often exhibit sudden unexpected death. Seizures in Kcna1−/− mice resemble those in well-characterized models of temporal lobe epilepsy known to involve limbic brain regions and spontaneous seizures result in enhanced cFos expression and neuronal death in the amygdala. Yet, the functional alterations leading to amygdala hyperexcitability have not been identified. In this study, we used Kcna1−/− mice to examine the contributions of Kv1.1 subunits to excitability in neuronal subtypes from basolateral (BLA) and central lateral (CeL) amygdala known to exhibit distinct firing patterns. We also analyzed synaptic transmission properties in an amygdala local circuit predicted to be involved in epilepsy-related comorbidities. Our data implicate Kv1.1 subunits in controlling spontaneous excitatory synaptic activity in BLA pyramidal neurons. In the CeL, Kv1.1 loss enhances intrinsic excitability and impairs inhibitory synaptic transmission, notably resulting in dysfunction of feed-forward inhibition, a critical mechanism for controlling spike timing. Overall, we find inhibitory control of CeL interneurons is reduced in Kcna1−/− mice suggesting that basal inhibitory network functioning is less able to prevent recurrent hyperexcitation related to seizures.
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37
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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38
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Massey CA, Thompson SJ, Ostrom RW, Drabek J, Sveinsson OA, Tomson T, Haas EA, Mena OJ, Goldman AM, Noebels JL. X-linked serotonin 2C receptor is associated with a non-canonical pathway for sudden unexpected death in epilepsy. Brain Commun 2021; 3:fcab149. [PMID: 34396109 PMCID: PMC8361391 DOI: 10.1093/braincomms/fcab149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/14/2021] [Accepted: 05/07/2021] [Indexed: 11/13/2022] Open
Abstract
Sudden Unexpected Death in Epilepsy is a leading cause of epilepsy-related mortality, and the analysis of mouse Sudden Unexpected Death in Epilepsy models is steadily revealing a spectrum of inherited risk phenotypes based on distinct genetic mechanisms. Serotonin (5-HT) signalling enhances post-ictal cardiorespiratory drive and, when elevated in the brain, reduces death following evoked audiogenic brainstem seizures in inbred mouse models. However, no gene in this pathway has yet been linked to a spontaneous epilepsy phenotype, the defining criterion of Sudden Unexpected Death in Epilepsy. Most monogenic models of Sudden Unexpected Death in Epilepsy invoke a failure of inhibitory synaptic drive as a critical pathogenic step. Accordingly, the G protein-coupled, membrane serotonin receptor 5-HT2C inhibits forebrain and brainstem networks by exciting GABAergic interneurons, and deletion of this gene lowers the threshold for lethal evoked audiogenic seizures. Here, we characterize epileptogenesis throughout the lifespan of mice lacking X-linked, 5-HT2C receptors (loxTB Htr2c). We find that loss of Htr2c generates a complex, adult-onset spontaneous epileptic phenotype with a novel progressive hyperexcitability pattern of absences, non-convulsive, and convulsive behavioural seizures culminating in late onset sudden mortality predominantly in male mice. RNAscope localized Htr2c mRNA in subsets of Gad2+ GABAergic neurons in forebrain and brainstem regions. To evaluate the contribution of 5-HT2C receptor-mediated inhibitory drive, we selectively spared their deletion in GAD2+ GABAergic neurons of pan-deleted loxTB Htr2c mice, yet unexpectedly found no amelioration of survival or epileptic phenotype, indicating that expression of 5-HT2C receptors in GAD2+ inhibitory neurons was not sufficient to prevent hyperexcitability and lethal seizures. Analysis of human Sudden Unexpected Death in Epilepsy and epilepsy genetic databases identified an enrichment of HTR2C non-synonymous variants in Sudden Unexpected Death in Epilepsy cases. Interestingly, while early lethality is not reflected in the mouse model, we also identified variants mainly among male Sudden Infant Death Syndrome patients. Our findings validate HTR2C as a novel, sex-linked candidate gene modifying Sudden Unexpected Death in Epilepsy risk, and demonstrate that the complex epilepsy phenotype does not arise solely from 5-HT2C-mediated synaptic disinhibition. These results strengthen the evidence for the serotonin hypothesis of Sudden Unexpected Death in Epilepsy risk in humans, and advance current efforts to develop gene-guided interventions to mitigate premature mortality in epilepsy.
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Affiliation(s)
- Cory A Massey
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Samantha J Thompson
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ryan W Ostrom
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Janice Drabek
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Olafur A Sveinsson
- Department of Neurology, National University Hospital of Iceland, 101 Reykjavik, Iceland
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Torbjörn Tomson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Elisabeth A Haas
- Department of Pathology, Rady Children’s Hospital-San Diego, San Diego, CA 92123, USA
| | - Othon J Mena
- Medical Examiner Office, Ventura County Health Care Agency, Ventura, CA 93003, USA
| | - Alica M Goldman
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jeffrey L Noebels
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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39
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Simeone KA, Wilke JC, Matthews SA, Simeone TA, Rho JM. Ketogenic diet-mediated seizure reduction preserves CA1 cell numbers in epileptic Kcna1-null mice: An unbiased stereological assessment. Epilepsia 2021; 62:e123-e128. [PMID: 34231878 DOI: 10.1111/epi.16983] [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: 01/14/2021] [Revised: 06/14/2021] [Accepted: 06/14/2021] [Indexed: 10/20/2022]
Abstract
There is growing evidence for the disease-modifying potential of metabolic therapies, including the ketogenic diet (KD), which is used to treat medically intractable epilepsy. However, it remains unclear whether the KD exerts direct effects on histopathological changes in epileptic brain, or whether the changes are a consequence of diet-induced reduction in seizure activity. Here, we used unbiased stereological techniques to quantify the seizure-induced reduction in cell number in the CA1 region of the hippocampus of epileptic Kcna1-null mice and compared the effects of the KD with that of phenobarbital (PB), a widely employed anti-seizure drug. Our data suggest that the anti-seizure activity of the KD or PB was similar. However, CA1 cell numbers of KD-treated hippocampi were not significantly different from those seen in wild-type (WT) mice, whereas CA1 cell counts in standard diet and PB-treated Kcna1-null mice were 23% and 31% lower than WT animals, respectively. These results support the notion that structural protection of cells may involve more than seizure attenuation, and that the KD engages mechanisms that also promote or restore hippocampal morphological integrity.
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Affiliation(s)
- Kristina A Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Julianne C Wilke
- Department of Pediatrics, University of California San Diego, San Diego, CA, USA.,Rady Children's Hospital San Diego, San Diego, CA, USA
| | - Stephanie A Matthews
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Timothy A Simeone
- Department of Pharmacology and Neuroscience, Creighton University School of Medicine, Omaha, NE, USA
| | - Jong M Rho
- Department of Pediatrics, University of California San Diego, San Diego, CA, USA.,Rady Children's Hospital San Diego, San Diego, CA, USA.,Department of Neurosciences, University of California San Diego, San Diego, CA, USA
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40
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Chou SM, Li KX, Huang MY, Chen C, Lin King YH, Li GG, Zhou W, Teo CF, Jan YN, Jan LY, Yang SB. Kv1.1 channels regulate early postnatal neurogenesis in mouse hippocampus via the TrkB signaling pathway. eLife 2021; 10:e58779. [PMID: 34018923 PMCID: PMC8208815 DOI: 10.7554/elife.58779] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 05/20/2021] [Indexed: 12/20/2022] Open
Abstract
In the postnatal brain, neurogenesis occurs only within a few regions, such as the hippocampal sub-granular zone (SGZ). Postnatal neurogenesis is tightly regulated by factors that balance stem cell renewal with differentiation, and it gives rise to neurons that participate in learning and memory formation. The Kv1.1 channel, a voltage-gated potassium channel, was previously shown to suppress postnatal neurogenesis in the SGZ in a cell-autonomous manner. In this study, we have clarified the physiological and molecular mechanisms underlying Kv1.1-dependent postnatal neurogenesis. First, we discovered that the membrane potential of neural progenitor cells is highly dynamic during development. We further established a multinomial logistic regression model for cell-type classification based on the biophysical characteristics and corresponding cell markers. We found that the loss of Kv1.1 channel activity causes significant depolarization of type 2b neural progenitor cells. This depolarization is associated with increased tropomyosin receptor kinase B (TrkB) signaling and proliferation of neural progenitor cells; suppressing TrkB signaling reduces the extent of postnatal neurogenesis. Thus, our study defines the role of the Kv1.1 potassium channel in regulating the proliferation of postnatal neural progenitor cells in mouse hippocampus.
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Affiliation(s)
- Shu-Min Chou
- Institute of Biomedical Sciences, Academia SinicaTaipeiTaiwan
| | - Ke-Xin Li
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | | | - Chao Chen
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Yuan-Hung Lin King
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Neuroscience Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | | | - Wei Zhou
- Department of Anesthesia and Perioperative Care, University of California, San FranciscoSan FranciscoUnited States
| | - Chin Fen Teo
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Lily Yeh Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Shi-Bing Yang
- Institute of Biomedical Sciences, Academia SinicaTaipeiTaiwan
- Neuroscience Program of Academia Sinica, Academia SinicaTaipeiTaiwan
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41
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Dhaibar HA, Hamilton KA, Glasscock E. Kv1.1 subunits localize to cardiorespiratory brain networks in mice where their absence induces astrogliosis and microgliosis. Mol Cell Neurosci 2021; 113:103615. [PMID: 33901631 DOI: 10.1016/j.mcn.2021.103615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 12/27/2022] Open
Abstract
Cardiorespiratory collapse following a seizure is a suspected cause of sudden unexpected death in epilepsy (SUDEP), the leading cause of epilepsy-related mortality. In the commonly used Kcna1 gene knockout (Kcna1-/-) mouse model of SUDEP, cardiorespiratory profiling reveals an array of aberrant breathing patterns that could contribute to risk of seizure-related mortality. However, the brain structures mediating these respiratory abnormalities remain unknown. We hypothesize that Kv1.1 deficiency in respiratory control centers of the brain contribute to respiratory dysfunction in Kcna1-/- mice leading to increased SUDEP risk. Thus, in this study, we first used immunohistochemistry to map expression of Kv1.1 protein in cardiorespiratory brain regions of wild-type Kcna1+/+ (WT) mice. Next, GFAP and Iba1 immunostaining was used to test for the presence of astrogliosis and microgliosis, respectively, in the cardiorespiratory centers of Kcna1-/- mice, which could be indicative of seizure-related brain injury that could impair breathing. In WT mice, we detected Kv1.1 protein in all cardiorespiratory centers examined, including the basolateral amygdala, dorsal respiratory group, dorsal motor nucleus of vagus, nucleus ambiguus, ventral respiratory column, and pontine respiratory group, as well as chemosensory centers including the retrotrapezoid and median raphae nuclei. Extensive gliosis was observed in the same areas in Kcna1-/- mice suggesting that seizure-associated brain injury could contribute to respiratory abnormalities.
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Affiliation(s)
- Hemangini A Dhaibar
- Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
| | - Kathryn A Hamilton
- Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
| | - Edward Glasscock
- Department of Cellular Biology & Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA, USA; Department of Biological Sciences, Southern Methodist University, Dallas, TX, USA.
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Indumathy J, Pruitt A, Gautier NM, Crane K, Glasscock E. Kv1.1 deficiency alters repetitive and social behaviors in mice and rescues autistic-like behaviors due to Scn2a haploinsufficiency. Brain Behav 2021; 11:e02041. [PMID: 33484493 PMCID: PMC8035482 DOI: 10.1002/brb3.2041] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 12/29/2020] [Accepted: 12/31/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Autism spectrum disorder (ASD) and epilepsy are highly comorbid, suggesting potential overlap in genetic etiology, pathophysiology, and neurodevelopmental abnormalities; however, the nature of this relationship remains unclear. This work investigated how two ion channel mutations, one associated with autism (Scn2a-null) and one with epilepsy (Kcna1-null), interact to modify genotype-phenotype relationships in the context of autism. Previous studies have shown that Scn2a+/- ameliorates epilepsy in Kcna1-/- mice, improving survival, seizure characteristics, and brain-heart dynamics. Here, we tested the converse, whether Kcna1 deletion modifies ASD-like repetitive and social behaviors in Scn2a+/- mice. METHODS Mice were bred with various combinations of Kcna1 and Scn2a knockout alleles. Animals were assessed for repetitive behaviors using marble burying, grooming, and nestlet shredding tests and for social behaviors using sociability and social novelty preference tests. RESULTS Behavioral testing revealed drastic reductions in all repetitive behaviors in epileptic Kcna1-/- mice, but relatively normal social interactions. In contrast, mice with partial Kcna1 deletion (Kcna1+/- ) exhibited increased self-grooming and decreased sociability suggestive of ASD-like features similar to those observed in Scn2a+/- mice. In double-mutant Scn2a+/- ; Kcna1+/- mice, the two mutations interacted to partially normalize ASD-like behaviors associated with each mutation independently. CONCLUSIONS Taken together, these findings suggest that Kv1.1 subunits are important in pathways and neural networks underlying ASD and that Kcna1 may be a therapeutic target for treatment of Scn2a-associated ASD.
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Affiliation(s)
- Jagadeeswaran Indumathy
- Department of Cellular Biology and AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
- Present address:
Department of Biological SciencesSouthern Methodist UniversityDallasTXUSA
| | - April Pruitt
- Department of Cellular Biology and AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Nicole M. Gautier
- Department of Cellular Biology and AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Kaitlin Crane
- Department of Cellular Biology and AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Edward Glasscock
- Department of Cellular Biology and AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
- Present address:
Department of Biological SciencesSouthern Methodist UniversityDallasTXUSA
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Abundant Monovalent Ions as Environmental Signposts for Pathogens during Host Colonization. Infect Immun 2021; 89:IAI.00641-20. [PMID: 33526568 DOI: 10.1128/iai.00641-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Host colonization by a pathogen requires proper sensing and response to local environmental cues, to ensure adaptation and continued survival within the host. The ionic milieu represents a critical potential source of environmental cues, and indeed, there has been extensive study of the interplay between host and pathogen in the context of metals such as iron, zinc, and manganese, vital ions that are actively sequestered by the host. The inherent non-uniformity of the ionic milieu also extends, however, to "abundant" ions such as chloride and potassium, whose concentrations vary greatly between tissue and cellular locations, and with the immune response. Despite this, the concept of abundant ions as environmental cues and key players in host-pathogen interactions is only just emerging. Focusing on chloride and potassium, this review brings together studies across multiple bacterial and parasitic species that have begun to define both how these abundant ions are exploited as cues during host infection, and how they can be actively manipulated by pathogens during host colonization. The close links between ion homeostasis and sensing/response to different ionic signals, and the importance of studying pathogen response to cues in combination, are also discussed, while considering the fundamental insight still to be uncovered from further studies in this nascent area of inquiry.
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44
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Qu S, Zhou C, Howe R, Shen W, Huang X, Catron M, Hu N, Macdonald RL. The K328M substitution in the human GABA A receptor gamma2 subunit causes GEFS+ and premature sudden death in knock-in mice. Neurobiol Dis 2021; 152:105296. [PMID: 33582225 PMCID: PMC8243844 DOI: 10.1016/j.nbd.2021.105296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/19/2021] [Accepted: 02/08/2021] [Indexed: 01/03/2023] Open
Affiliation(s)
- Shimian Qu
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America.
| | - Chengwen Zhou
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America.
| | - Rachel Howe
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America.
| | - Wangzhen Shen
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America.
| | - Xuan Huang
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America.
| | - Mackenzie Catron
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America.
| | - Ningning Hu
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America.
| | - Robert L Macdonald
- Departments of Neurology, Vanderbilt University, Nashville, TN 37232, United States of America; Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, United States of America; Pharmacology, Vanderbilt University, Nashville, TN 37232, United States of America.
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45
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Hoang Trung H, Yoshihara T, Nakao A, Hayashida K, Hirata Y, Shirasuna K, Kuwamura M, Nakagawa Y, Kaneko T, Mori Y, Asano M, Kuramoto T. Deficiency of the RIβ subunit of protein kinase A causes body tremor and impaired fear conditioning memory in rats. Sci Rep 2021; 11:2039. [PMID: 33479380 PMCID: PMC7820254 DOI: 10.1038/s41598-021-81515-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/06/2021] [Indexed: 11/09/2022] Open
Abstract
The RIβ subunit of cAMP-dependent protein kinase (PKA), encoded by Prkar1b, is a neuronal isoform of the type I regulatory subunit of PKA. Mice lacking the RIβ subunit exhibit normal long-term potentiation (LTP) in the Schaffer collateral pathway of the hippocampus and normal behavior in the open-field and fear conditioning tests. Here, we combined genetic, electrophysiological, and behavioral approaches to demonstrate that the RIβ subunit was involved in body tremor, LTP in the Schaffer collateral pathway, and fear conditioning memory in rats. Genetic analysis of WTC-furue, a mutant strain with spontaneous tremors, revealed a deletion in the Prkar1b gene of the WTC-furue genome. Prkar1b-deficient rats created by the CRISPR/Cas9 system exhibited body tremor. Hippocampal slices from mutant rats showed deficient LTP in the Schaffer collateral-CA1 synapse. Mutant rats also exhibited decreased freezing time following contextual and cued fear conditioning, as well as increased exploratory behavior in the open field. These findings indicate the roles of the RIβ subunit in tremor pathogenesis and contextual and cued fear memory, and suggest that the hippocampal and amygdala roles of this subunit differ between mice and rats and that rats are therefore beneficial for exploring RIβ function.
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Affiliation(s)
- Hieu Hoang Trung
- Laboratory of Animal Nutrition, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa, 243-0034, Japan
| | - Toru Yoshihara
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Akito Nakao
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Katsumi Hayashida
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Yoshiki Hirata
- Laboratory of Animal Reproduction, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa, 243-0034, Japan
| | - Koumei Shirasuna
- Laboratory of Animal Reproduction, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa, 243-0034, Japan
| | - Mitsuru Kuwamura
- Laboratory of Veterinary Pathology, Graduate School of Life and Environmental Science, Osaka Prefecture University, 1-58 Rinkuuourai-kita, Izumisano, Osaka, 598-8531, Japan
| | - Yuki Nakagawa
- Department of Chemistry and Biological Sciences, Faculty of Science and Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan
| | - Takehito Kaneko
- Department of Chemistry and Biological Sciences, Faculty of Science and Engineering, Iwate University, 4-3-5 Ueda, Morioka, Iwate, 020-8551, Japan
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
| | - Masahide Asano
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Takashi Kuramoto
- Laboratory of Animal Nutrition, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa, 243-0034, Japan. .,Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan.
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46
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Musculoskeletal Features without Ataxia Associated with a Novel de novo Mutation in KCNA1 Impairing the Voltage Sensitivity of Kv1.1 Channel. Biomedicines 2021; 9:biomedicines9010075. [PMID: 33466780 PMCID: PMC7829709 DOI: 10.3390/biomedicines9010075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/02/2021] [Accepted: 01/06/2021] [Indexed: 02/06/2023] Open
Abstract
The KCNA1 gene encodes the α subunit of the voltage-gated Kv1.1 potassium channel that critically regulates neuronal excitability in the central and peripheral nervous systems. Mutations in KCNA1 have been classically associated with episodic ataxia type 1 (EA1), a movement disorder triggered by physical and emotional stress. Additional features variably reported in recent years include epilepsy, myokymia, migraine, paroxysmal dyskinesia, hyperthermia, hypomagnesemia, and cataplexy. Interestingly, a few individuals with neuromyotonia, either isolated or associated with skeletal deformities, have been reported carrying variants in the S2–S3 transmembrane segments of Kv1.1 channels in the absence of any other symptoms. Here, we have identified by whole-exome sequencing a novel de novo variant, T268K, in KCNA1 in a boy displaying recurrent episodes of neuromyotonia, muscle hypertrophy, and skeletal deformities. Through functional analysis in heterologous cells and structural modeling, we show that the mutation, located at the extracellular end of the S3 helix, causes deleterious effects, disrupting Kv1.1 function by altering the voltage dependence of activation and kinetics of deactivation, likely due to abnormal interactions with the voltage sensor in the S4 segment. Our study supports previous evidence suggesting that specific residues within the S2 and S3 segments of Kv1.1 result in a distinctive phenotype with predominant musculoskeletal presentation.
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Zhang L, Peng Z, Bian W, Zhu P, Tang B, Liao WP, Su T. Functional Differences Between Two Kv1.1 RNA Editing Isoforms: a Comparative Study on Neuronal Overexpression in Mouse Prefrontal Cortex. Mol Neurobiol 2021; 58:2046-2060. [PMID: 33411244 DOI: 10.1007/s12035-020-02229-1] [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: 07/20/2020] [Accepted: 11/24/2020] [Indexed: 10/22/2022]
Abstract
The Shaker-related potassium channel Kv1.1 subunit has important implications for controlling neuronal excitabilities. A particular recoding by A-to-I RNA editing at I400 of Kv1.1 mRNA is an underestimated mechanism for fine-tuning the properties of Kv1.1-containing channels. Knowledge about functional differences between edited (I400V) and non-edited Kv1.1 isoforms is insufficient, especially in neurons. To understand their different roles, the two Kv1.1 isoforms were overexpressed in the prefrontal cortex via local adeno-associated virus-mediated gene delivery. The I400V isoform showed a higher competitiveness in membrane translocalization, but failed to reduce current-evoked discharges and showed weaker impact on spiking-frequency adaptation in the transduced neurons. The non-edited Kv1.1 overexpression led to slight elevations in both fast- and non-inactivating current components of macroscopic potassium current. By contrast, the I400V overexpression did not impact the fast-inactivating current component. Further isolation of Kv1.1-specific current by its specific blocker dendrotoxin-κ showed that both isoforms did result in significant increases in current amplitude, whereas the I400V was less efficient in contributing the fast-inactivating current component. Voltage-dependent properties of the fast-inactivating current component did not alter for both isoforms. For recovery kinetics, the I400V showed a significant acceleration of recovery from fast inactivation. The gene delivery of the I400V rather than the wild type exhibited anxiolytic activities, which was assessed by an open field test. These results suggest that the Kv1.1 RNA editing isoforms have different properties and outcomes, reflecting the functional and phenotypic significance of the Kv1.1 RNA editing in neurons.
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Affiliation(s)
- Liting Zhang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Chang-gang-dong Road 250, Guangzhou, 510260, China.,Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Zetong Peng
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Chang-gang-dong Road 250, Guangzhou, 510260, China.,Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Wenjun Bian
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Chang-gang-dong Road 250, Guangzhou, 510260, China.,Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Pingping Zhu
- Department of Neurology, Guangzhou Red Cross Hospital, Medical College, Jinan University, Guangzhou, China
| | - Bin Tang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Chang-gang-dong Road 250, Guangzhou, 510260, China.,Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Wei-Ping Liao
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Chang-gang-dong Road 250, Guangzhou, 510260, China.,Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Tao Su
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Chang-gang-dong Road 250, Guangzhou, 510260, China. .,Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China.
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48
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Chan F, Liu J. Molecular regulation of brain metabolism underlying circadian epilepsy. Epilepsia 2021; 62 Suppl 1:S32-S48. [PMID: 33395505 DOI: 10.1111/epi.16796] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 12/01/2020] [Accepted: 12/01/2020] [Indexed: 12/13/2022]
Abstract
Extensive study has demonstrated that epilepsy occurs with greater frequency at certain times in the 24-h cycle. Although these findings implicate an overlap between the circadian rhythm and epilepsy, the molecular and cellular mechanisms underlying this circadian regulation are poorly understood. Because the 24-h rhythm is generated by the circadian molecular system, it is not surprising that this system comprised of many circadian genes is implicated in epilepsy. We summarized evidence in the literature implicating various circadian genes such as Clock, Bmal1, Per1, Rev-erb⍺, and Ror⍺ in epilepsy. In various animal models of epilepsy, the circadian oscillation and the steady-state level of these genes are disrupted. The downstream pathway of these genes involves a large number of metabolic pathways associated with epilepsy. These pathways include pyridoxal metabolism, the mammalian target of rapamycin pathway, and the regulation of redox state. We propose that disruption of these metabolic pathways could mediate the circadian regulation of epilepsy. A greater understanding of the cellular and molecular mechanism of circadian regulation of epilepsy would enable us to precisely target the circadian disruption in epilepsy for a novel therapeutic approach.
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Affiliation(s)
- Felix Chan
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island, USA
| | - Judy Liu
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island, USA.,Department of Neurology, Warren Alpert Medical School, Brown University, Providence, Rhode Island, USA
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49
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Trosclair K, Si M, Watts M, Gautier NM, Voigt N, Traylor J, Bitay M, Baczko I, Dobrev D, Hamilton KA, Bhuiyan MS, Dominic P, Glasscock E. Kv1.1 potassium channel subunit deficiency alters ventricular arrhythmia susceptibility, contractility, and repolarization. Physiol Rep 2021; 9:e14702. [PMID: 33427415 PMCID: PMC7798052 DOI: 10.14814/phy2.14702] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 12/11/2022] Open
Abstract
Epilepsy-associated Kv1.1 voltage-gated potassium channel subunits encoded by the Kcna1 gene have traditionally been considered absent in heart, but recent studies reveal they are expressed in cardiomyocytes where they could regulate intrinsic cardiac electrophysiology. Although Kv1.1 now has a demonstrated functional role in atria, its role in the ventricles has never been investigated. In this work, electrophysiological, histological, and gene expression approaches were used to explore the consequences of Kv1.1 deficiency in the ventricles of Kcna1 knockout (KO) mice at the organ, cellular, and molecular levels to determine whether the absence of Kv1.1 leads to ventricular dysfunction that increases the risk of premature or sudden death. When subjected to intracardiac pacing, KO mice showed normal baseline susceptibility to inducible ventricular arrhythmias (VA) but resistance to VA under conditions of sympathetic challenge with isoproterenol. Echocardiography revealed cardiac contractile dysfunction manifesting as decreased ejection fraction and fractional shortening. In whole-cell patch-clamp recordings, KO ventricular cardiomyocytes exhibited action potential prolongation indicative of impaired repolarization. Imaging, histological, and transcript analyses showed no evidence of structural or channel gene expression remodeling, suggesting that the observed deficits are likely electrogenic due to Kv1.1 deficiency. Immunoblots of patient heart samples detected the presence of Kv1.1 at relatively high levels, implying that Kv1.1 contributes to human cardiac electrophysiology. Taken together, this work describes an important functional role for Kv1.1 in ventricles where its absence causes repolarization and contractility deficits but reduced susceptibility to arrhythmia under conditions of sympathetic drive.
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Affiliation(s)
- Krystle Trosclair
- Department of Cellular Biology & AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Man Si
- Department of Cellular Biology & AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Megan Watts
- Department of Internal MedicineSection of CardiologyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Nicole M. Gautier
- Department of Cellular Biology & AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Niels Voigt
- Institute of Pharmacology and ToxicologyUniversity Medical Center GoettingenGoettingenGermany
- DZHK (German Center for Cardiovascular Research)GöttingenGermany
| | - James Traylor
- Department of PathologyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Miklós Bitay
- Department of Cardiac Surgery2nd Department of Medicine and Cardiology CenterUniversity of SzegedSzegedHungary
| | - Istvan Baczko
- Department of Pharmacology and PharmacotherapyInterdisciplinary Excellence CentreUniversity of SzegedSzegedHungary
| | - Dobromir Dobrev
- Institute of PharmacologyWest German Heart and Vascular CenterUniversity Duisburg‐EssenEssenGermany
| | - Kathryn A. Hamilton
- Department of Cellular Biology & AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Md. Shenuarin Bhuiyan
- Department of PathologyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Paari Dominic
- Department of Internal MedicineSection of CardiologyLouisiana State University Health Sciences CenterShreveportLAUSA
| | - Edward Glasscock
- Department of Cellular Biology & AnatomyLouisiana State University Health Sciences CenterShreveportLAUSA
- Department of Biological SciencesSouthern Methodist UniversityDallasTXUSA
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50
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Koga Y, Tsuchimoto D, Hayashi Y, Abolhassani N, Yoneshima Y, Sakumi K, Nakanishi H, Toyokuni S, Nakabeppu Y. Neural stem cell-specific ITPA deficiency causes neural depolarization and epilepsy. JCI Insight 2020; 5:140229. [PMID: 33208550 PMCID: PMC7710303 DOI: 10.1172/jci.insight.140229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/15/2020] [Indexed: 11/17/2022] Open
Abstract
Inosine triphosphate pyrophosphatase (ITPA) hydrolyzes inosine triphosphate (ITP) and other deaminated purine nucleotides to the corresponding nucleoside monophosphates. In humans, ITPA deficiency causes severe encephalopathy with epileptic seizure, microcephaly, and developmental retardation. In this study, we established neural stem cell-specific Itpa-conditional KO mice (Itpa-cKO mice) to clarify the effects of ITPA deficiency on the neural system. The Itpa-cKO mice showed growth retardation and died within 3 weeks of birth. We did not observe any microcephaly in the Itpa-cKO mice, although the female Itpa-cKO mice did show adrenal hypoplasia. The Itpa-cKO mice showed limb-clasping upon tail suspension and spontaneous and/or audiogenic seizure. Whole-cell patch-clamp recordings from entorhinal cortex neurons in brain slices revealed a depolarized resting membrane potential, increased firing, and frequent spontaneous miniature excitatory postsynaptic current and miniature inhibitory postsynaptic current in the Itpa-cKO mice compared with ITPA-proficient controls. Accumulated ITP or its metabolites, such as cyclic inosine monophosphates, or RNA containing inosines may cause membrane depolarization and hyperexcitability in neurons and induce the phenotype of ITPA-deficient mice, including seizure.
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Affiliation(s)
- Yuichiro Koga
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Daisuke Tsuchimoto
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Yoshinori Hayashi
- Department of Aging Science and Pharmacology, Faculty of Dental Sciences, Kyushu University, Fukuoka, Japan
- Department of Physiology, Nihon University School of Dentistry, Tokyo, Japan
| | - Nona Abolhassani
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Yasuto Yoneshima
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Kunihiko Sakumi
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
| | - Hiroshi Nakanishi
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women’s University, Hiroshima, Japan
| | - Shinya Toyokuni
- Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yusaku Nakabeppu
- Division of Neurofunctional Genomics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation, and
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