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Kuramoto T. Positional cloning of rat mutant genes reveals new functions of these genes. Exp Anim 2023; 72:1-8. [PMID: 36058846 PMCID: PMC9978133 DOI: 10.1538/expanim.22-0089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The laboratory rat (Rattus norvegicus) is a key model organism for biomedical research. Rats can be subjected to strict genetic and environmental controls. The rat's large body size is suitable for both surgical operations and repeated measurements of physiological parameters. These advantages have led to the development of numerous rat models for genetic diseases. Forward genetics is a proven approach for identifying the causative genes of these disease models but requires genome resources including genetic markers and genome sequences. Over the last few decades, rat genome resources have been developed and deposited in bioresource centers, which have enabled us to perform positional cloning in rats. To date, more than 100 disease-related genes have been identified by positional cloning. Since some disease models are more accessible in rats than mice, the identification of causative genes in these models has sometimes led to the discovery of novel functions of genes. As before, various mutant rats are also expected to be discovered and developed as disease models in the future. Thus, the forward genetics continues to be an important approach to find genes involved in disease phenotypes in rats. In this review, I provide an overview the development of rat genome resources and describe examples of positional cloning in rats in which novel gene functions have been identified.
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Affiliation(s)
- Takashi Kuramoto
- Laboratory of Animal Nutrition, Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa 243-0034, Japan
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2
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Thioredoxin deficiency increases oxidative stress and causes bilateral symmetrical degeneration in rat midbrain. Neurobiol Dis 2022; 175:105921. [DOI: 10.1016/j.nbd.2022.105921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 10/26/2022] [Accepted: 11/07/2022] [Indexed: 11/13/2022] Open
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Nikitin ES, Vinogradova LV. Potassium channels as prominent targets and tools for the treatment of epilepsy. Expert Opin Ther Targets 2021; 25:223-235. [PMID: 33754930 DOI: 10.1080/14728222.2021.1908263] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION K+ channels are of great interest to epilepsy research as mutations in their genes are found in humans with inherited epilepsy. At the level of cellular physiology, K+ channels control neuronal intrinsic excitability and are the main contributors to membrane repolarization of active neurons. Recently, a genetically modified voltage-dependent K+ channel has been patented as a remedy for epileptic seizures. AREAS COVERED We review the role of potassium channels in excitability, clinical and experimental evidence for the association of potassium channelopathies with epilepsy, the targeting of K+ channels by drugs, and perspectives of gene therapy in epilepsy with the expression of extra K+ channels in the brain. EXPERT OPINION Control over K+ conductance is of great potential benefit for the treatment of epilepsy. Nowadays, gene therapy affecting K+ channels is one of the most promising approaches to treat pharmacoresistant focal epilepsy.
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Affiliation(s)
- E S Nikitin
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | - L V Vinogradova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
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4
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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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Koźmiński W, Pera J. Involvement of the Peripheral Nervous System in Episodic Ataxias. Biomedicines 2020; 8:biomedicines8110448. [PMID: 33105744 PMCID: PMC7690566 DOI: 10.3390/biomedicines8110448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 12/04/2022] Open
Abstract
Episodic ataxias comprise a group of inherited disorders, which have a common hallmark—transient attacks of ataxia. The genetic background is heterogeneous and the causative genes are not always identified. Furthermore, the clinical presentation, including intraictal and interictal symptoms, as well as the retention and progression of neurological deficits, is heterogeneous. Spells of ataxia can be accompanied by other symptoms—mostly from the central nervous system. However, in some of episodic ataxias involvement of peripheral nervous system is a part of typical clinical picture. This review intends to provide an insight into involvement of peripheral nervous system in episodic ataxias.
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Affiliation(s)
- Wojciech Koźmiński
- Department of Neurology, University Hospital, ul. Jakubowskiego 2, 30-688 Krakow, Poland;
| | - Joanna Pera
- Department of Neurology, Jagiellonian University Medical College, ul. Botaniczna 3, 31-503 Krakow, Poland
- Correspondence:
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6
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Giunti P, Mantuano E, Frontali M. Episodic Ataxias: Faux or Real? Int J Mol Sci 2020; 21:ijms21186472. [PMID: 32899446 PMCID: PMC7555854 DOI: 10.3390/ijms21186472] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 08/31/2020] [Accepted: 09/01/2020] [Indexed: 11/22/2022] Open
Abstract
The term Episodic Ataxias (EA) was originally used for a few autosomal dominant diseases, characterized by attacks of cerebellar dysfunction of variable duration and frequency, often accompanied by other ictal and interictal signs. The original group subsequently grew to include other very rare EAs, frequently reported in single families, for some of which no responsible gene was found. The clinical spectrum of these diseases has been enormously amplified over time. In addition, episodes of ataxia have been described as phenotypic variants in the context of several different disorders. The whole group is somewhat confused, since a strong evidence linking the mutation to a given phenotype has not always been established. In this review we will collect and examine all instances of ataxia episodes reported so far, emphasizing those for which the pathophysiology and the clinical spectrum is best defined.
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Affiliation(s)
- Paola Giunti
- Laboratory of Neurogenetics, Department of Molecular Neuroscience, UCL Institute of Neurology, London WC2N 5DU, UK
- Correspondence: (P.G.); (M.F.)
| | - Elide Mantuano
- Laboratory of Neurogenetics, Institute of Translational Pharmacology, National Research Council of Italy, 00133 Rome, Italy;
| | - Marina Frontali
- Laboratory of Neurogenetics, Institute of Translational Pharmacology, National Research Council of Italy, 00133 Rome, Italy;
- Correspondence: (P.G.); (M.F.)
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7
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Szpirer C. Rat models of human diseases and related phenotypes: a systematic inventory of the causative genes. J Biomed Sci 2020; 27:84. [PMID: 32741357 PMCID: PMC7395987 DOI: 10.1186/s12929-020-00673-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
The laboratory rat has been used for a long time as the model of choice in several biomedical disciplines. Numerous inbred strains have been isolated, displaying a wide range of phenotypes and providing many models of human traits and diseases. Rat genome mapping and genomics was considerably developed in the last decades. The availability of these resources has stimulated numerous studies aimed at discovering causal disease genes by positional identification. Numerous rat genes have now been identified that underlie monogenic or complex diseases and remarkably, these results have been translated to the human in a significant proportion of cases, leading to the identification of novel human disease susceptibility genes, helping in studying the mechanisms underlying the pathological abnormalities and also suggesting new therapeutic approaches. In addition, reverse genetic tools have been developed. Several genome-editing methods were introduced to generate targeted mutations in genes the function of which could be clarified in this manner [generally these are knockout mutations]. Furthermore, even when the human gene causing a disease had been identified without resorting to a rat model, mutated rat strains (in particular KO strains) were created to analyze the gene function and the disease pathogenesis. Today, over 350 rat genes have been identified as underlying diseases or playing a key role in critical biological processes that are altered in diseases, thereby providing a rich resource of disease models. This article is an update of the progress made in this research and provides the reader with an inventory of these disease genes, a significant number of which have similar effects in rat and humans.
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Affiliation(s)
- Claude Szpirer
- Université Libre de Bruxelles, B-6041, Gosselies, Belgium.
- , Waterloo, Belgium.
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8
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D’Adamo MC, Liantonio A, Rolland JF, Pessia M, Imbrici P. Kv1.1 Channelopathies: Pathophysiological Mechanisms and Therapeutic Approaches. Int J Mol Sci 2020; 21:ijms21082935. [PMID: 32331416 PMCID: PMC7215777 DOI: 10.3390/ijms21082935] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 04/19/2020] [Accepted: 04/20/2020] [Indexed: 12/27/2022] Open
Abstract
Kv1.1 belongs to the Shaker subfamily of voltage-gated potassium channels and acts as a critical regulator of neuronal excitability in the central and peripheral nervous systems. KCNA1 is the only gene that has been associated with episodic ataxia type 1 (EA1), an autosomal dominant disorder characterized by ataxia and myokymia and for which different and variable phenotypes have now been reported. The iterative characterization of channel defects at the molecular, network, and organismal levels contributed to elucidating the functional consequences of KCNA1 mutations and to demonstrate that ataxic attacks and neuromyotonia result from cerebellum and motor nerve alterations. Dysfunctions of the Kv1.1 channel have been also associated with epilepsy and kcna1 knock-out mouse is considered a model of sudden unexpected death in epilepsy. The tissue-specific association of Kv1.1 with other Kv1 members, auxiliary and interacting subunits amplifies Kv1.1 physiological roles and expands the pathogenesis of Kv1.1-associated diseases. In line with the current knowledge, Kv1.1 has been proposed as a novel and promising target for the treatment of brain disorders characterized by hyperexcitability, in the attempt to overcome limited response and side effects of available therapies. This review recounts past and current studies clarifying the roles of Kv1.1 in and beyond the nervous system and its contribution to EA1 and seizure susceptibility as well as its wide pharmacological potential.
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Affiliation(s)
- Maria Cristina D’Adamo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida MDS-2080, Malta; (M.C.D.); (M.P.)
| | - Antonella Liantonio
- Department of Pharmacy–Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy;
| | | | - Mauro Pessia
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida MDS-2080, Malta; (M.C.D.); (M.P.)
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain Po Box 17666, UAE
| | - Paola Imbrici
- Department of Pharmacy–Drug Sciences, University of Bari “Aldo Moro”, 70125 Bari, Italy;
- Correspondence:
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9
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Clinical Spectrum of KCNA1 Mutations: New Insights into Episodic Ataxia and Epilepsy Comorbidity. Int J Mol Sci 2020; 21:ijms21082802. [PMID: 32316562 PMCID: PMC7215408 DOI: 10.3390/ijms21082802] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/14/2020] [Accepted: 04/16/2020] [Indexed: 12/13/2022] Open
Abstract
Mutations in the KCNA1 gene, which encodes voltage-gated Kv1.1 potassium channel α-subunits, cause a variety of human diseases, complicating simple genotype–phenotype correlations in patients. KCNA1 mutations are primarily associated with a rare neurological movement disorder known as episodic ataxia type 1 (EA1). However, some patients have EA1 in combination with epilepsy, whereas others have epilepsy alone. KCNA1 mutations can also cause hypomagnesemia and paroxysmal dyskinesia in rare cases. Why KCNA1 variants are associated with such phenotypic heterogeneity in patients is not yet understood. In this review, literature databases (PubMed) and public genetic archives (dbSNP and ClinVar) were mined for known pathogenic or likely pathogenic mutations in KCNA1 to examine whether patterns exist between mutation type and disease manifestation. Analyses of the 47 deleterious KCNA1 mutations that were identified revealed that epilepsy or seizure-related variants tend to cluster in the S1/S2 transmembrane domains and in the pore region of Kv1.1, whereas EA1-associated variants occur along the whole length of the protein. In addition, insights from animal models of KCNA1 channelopathy were considered, as well as the possible influence of genetic modifiers on disease expressivity and severity. Elucidation of the complex relationship between KCNA1 variants and disease will enable better diagnostic risk assessment and more personalized therapeutic strategies for KCNA1 channelopathy.
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10
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Manville RW, Abbott GW. Isoform-Selective KCNA1 Potassium Channel Openers Built from Glycine. J Pharmacol Exp Ther 2020; 373:391-401. [PMID: 32217768 DOI: 10.1124/jpet.119.264507] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 03/24/2020] [Indexed: 12/18/2022] Open
Abstract
Loss of function of voltage-gated potassium (Kv) channels is linked to a range of lethal or debilitating channelopathies. New pharmacological approaches are warranted to isoform-selectively activate specific Kv channels. One example is KCNA1 Potassium Voltage-Gated Channel Subfamily A Member 1 (KCNA1) (Kv1.1), an archetypal Shaker-type Kv channel, in which loss-of-function mutations cause episodic ataxia type 1 (EA1). EA1 causes constant myokomia and episodic bouts of ataxia and may associate with epilepsy and other disorders. We previously found that the inhibitory neurotransmitter γ-aminobutyric acid and modified versions of glycine directly activate Kv channels within the KCNQ subfamily, a characteristic favored by strong negative electrostatic surface potential near the neurotransmitter carbonyl group. Here, we report that adjusting the number and positioning of fluorine atoms within the fluorophenyl ring of glycine derivatives produces isoform-selective KCNA1 channel openers that are inactive against KCNQ2/3 channels, or even KCNA2, the closest relative of KCNA1. The findings refine our understanding of the molecular basis for KCNQ versus KCNA1 activation and isoform selectivity and constitute, to our knowledge, the first reported isoform-selective KCNA1 opener. SIGNIFICANCE STATEMENT: Inherited loss-of-function gene sequence variants in KCNA1, which encodes the KCNA1 (Kv1.1) voltage-gated potassium channel, cause episodic ataxia type 1 (EA1), a movement disorder also linked to epilepsy and developmental delay. We have discovered several isoform-specific KCNA1-activating small molecules, addressing a notable gap in the field and providing possible lead compounds and a novel chemical space for the development of potential future therapeutic drugs for EA1.
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Affiliation(s)
- Rían W Manville
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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11
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Wei S, Liang XZ, Hu Q, Wang WS, Xu WJ, Cheng XQ, Peng J, Guo QY, Liu SY, Jiang W, Ding X, Han GH, Liu P, Shi CH, Wang Y. Different protein expression patterns in rat spinal nerves during Wallerian degeneration assessed using isobaric tags for relative and absolute quantitation proteomics profiling. Neural Regen Res 2020; 15:315-323. [PMID: 31552905 PMCID: PMC6905349 DOI: 10.4103/1673-5374.265556] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Sensory and motor nerve fibers of peripheral nerves have different anatomies and regeneration functions after injury. To gain a clear understanding of the biological processes behind these differences, we used a labeling technique termed isobaric tags for relative and absolute quantitation to investigate the protein profiles of spinal nerve tissues from Sprague-Dawley rats. In response to Wallerian degeneration, a total of 626 proteins were screened in sensory nerves, of which 368 were upregulated and 258 were downregulated. In addition, 637 proteins were screened in motor nerves, of which 372 were upregulated and 265 were downregulated. All identified proteins were analyzed using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of bioinformatics, and the presence of several key proteins closely related to Wallerian degeneration were tested and verified using quantitative real-time polymerase chain reaction analyses. The differentially expressed proteins only identified in the sensory nerves were mainly relevant to various biological processes that included cell-cell adhesion, carbohydrate metabolic processes and cell adhesion, whereas differentially expressed proteins only identified in the motor nerves were mainly relevant to biological processes associated with the glycolytic process, cell redox homeostasis, and protein folding. In the aspect of the cellular component, the differentially expressed proteins in the sensory and motor nerves were commonly related to extracellular exosomes, the myelin sheath, and focal adhesion. According to the Kyoto Encyclopedia of Genes and Genomes, the differentially expressed proteins identified are primarily related to various types of metabolic pathways. In conclusion, the present study screened differentially expressed proteins to reveal more about the differences and similarities between sensory and motor nerves during Wallerian degeneration. The present findings could provide a reference point for a future investigation into the differences between sensory and motor nerves in Wallerian degeneration and the characteristics of peripheral nerve regeneration. The study was approved by the Ethics Committee of the Chinese PLA General Hospital, China (approval No. 2016-x9-07) in September 2016.
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Affiliation(s)
- Shuai Wei
- The First Affiliated Hospital of Medical College, Shihezi University, Shihezi, Xinjiang Uygur Autonomous Region; Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Xue-Zhen Liang
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing; The First Clinical Medical School, Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
| | - Qian Hu
- The First Affiliated Hospital of Medical College, Shihezi University, Shihezi, Xinjiang Uygur Autonomous Region, China
| | - Wei-Shan Wang
- The First Affiliated Hospital of Medical College, Shihezi University, Shihezi, Xinjiang Uygur Autonomous Region, China
| | - Wen-Jing Xu
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing, China
| | - Xiao-Qing Cheng
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Jiang Peng
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Quan-Yi Guo
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing, China
| | - Shu-Yun Liu
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing, China
| | - Wen Jiang
- The First Affiliated Hospital of Medical College, Shihezi University, Shihezi, Xinjiang Uygur Autonomous Region; Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Xiao Ding
- The First Affiliated Hospital of Medical College, Shihezi University, Shihezi, Xinjiang Uygur Autonomous Region; Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Gong-Hai Han
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province; Kunming Medical University, Kunming, Yunnan Province, China
| | - Ping Liu
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province; Shanxi Medical University, Taiyuan, Shanxi Province, China
| | - Chen-Hui Shi
- The First Affiliated Hospital of Medical College, Shihezi University, Shihezi, Xinjiang Uygur Autonomous Region, China
| | - Yu Wang
- Institute of Orthopedics, Chinese PLA General Hospital, Beijing; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
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12
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Verdura E, Fons C, Schlüter A, Ruiz M, Fourcade S, Casasnovas C, Castellano A, Pujol A. Complete loss of KCNA1 activity causes neonatal epileptic encephalopathy and dyskinesia. J Med Genet 2019; 57:132-137. [PMID: 31586945 PMCID: PMC7029237 DOI: 10.1136/jmedgenet-2019-106373] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/12/2019] [Accepted: 09/15/2019] [Indexed: 11/29/2022]
Abstract
Background Since 1994, over 50 families affected by the episodic ataxia type 1 disease spectrum have been described with mutations in KCNA1, encoding the voltage-gated K+ channel subunit Kv1.1. All of these mutations are either transmitted in an autosomal-dominant mode or found as de novo events. Methods A patient presenting with a severe combination of dyskinesia and neonatal epileptic encephalopathy was sequenced by whole-exome sequencing (WES). A candidate variant was tested using cellular assays and patch-clamp recordings. Results WES revealed a homozygous variant (p.Val368Leu) in KCNA1, involving a conserved residue in the pore domain, close to the selectivity signature sequence for K+ ions (TVGYG). Functional analysis showed that mutant protein alone failed to produce functional channels in homozygous state, while coexpression with wild-type produced no effects on K+ currents, similar to wild-type protein alone. Treatment with oxcarbazepine, a sodium channel blocker, proved effective in controlling seizures. Conclusion This newly identified variant is the first to be reported to act in a recessive mode of inheritance in KCNA1. These findings serve as a cautionary tale for the diagnosis of channelopathies, in which an unreported phenotypic presentation or mode of inheritance for the variant of interest can hinder the identification of causative variants and adequate treatment choice.
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Affiliation(s)
- Edgard Verdura
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Carme Fons
- Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.,Pediatric Neurology Department, Hospital Sant Joan de Déu, Esplugues de Llobregat, Barcelona, Catalunya, Spain.,Sant Joan de Déu Research Institute (IRSJD), Esplugues de Llobregat, Barcelona, Catalunya, Spain
| | - Agatha Schlüter
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Montserrat Ruiz
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Stéphane Fourcade
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Carlos Casasnovas
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain.,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.,Neuromuscular Unit, Neurology Department, Hospital Universitari de Bellvitge, L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain
| | - Antonio Castellano
- Institute of Biomedicine of Seville (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.,Medical Physiology and Biophysics Departament, Universidad de Sevilla, Sevilla, Spain
| | - Aurora Pujol
- Neurometabolic Diseases Laboratory, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Catalunya, Spain .,Centre for Biomedical Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.,Catalan Institution of Research and Advanced Studies (ICREA), Barcelona, Catalunya, Spain
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Niespodziany I, Mullier B, André VM, Ghisdal P, Jnoff E, Moreno-Delgado D, Swinnen D, Sands Z, Wood M, Wolff C. Discovery of a small molecule modulator of the Kv1.1/Kvβ1 channel complex that reduces neuronal excitability and in vitro epileptiform activity. CNS Neurosci Ther 2018; 25:442-451. [PMID: 30242974 DOI: 10.1111/cns.13060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 11/27/2022] Open
Abstract
AIMS Kv1.1 (KCNA1) channels contribute to the control of neuronal excitability and have been associated with epilepsy. Kv1.1 channels can associate with the cytoplasmic Kvβ1 subunit resulting in rapid inactivating A-type currents. We hypothesized that removal of channel inactivation, by modulating Kv1.1/Kvβ1 interaction with a small molecule, would lead to decreased neuronal excitability and anticonvulsant activity. METHODS We applied high-throughput screening to identify ligands able to modulate the Kv1.1-T1 domain/Kvβ1 protein complex. We then selected a compound that was characterized on recombinant Kv1.1/Kvβ1 channels by electrophysiology and further evaluated on sustained neuronal firing and on in vitro epileptiform activity using a high K+ -low Ca2+ model in hippocampal slices. RESULTS We identified a novel compound able to modulate the interaction of the Kv1.1/Kvβ1 complex and that produced a functional inhibition of Kv1.1/Kvβ1 channel inactivation. We demonstrated that this compound reduced the sustained repetitive firing in hippocampal neurons and was able to abolish the development of in vitro epileptiform activity. CONCLUSIONS This study describes a rational drug discovery approach for the identification of novel ligands that inhibit Kv1.1 channel inactivation and provides pharmacological evidence that such a mechanism translates into physiological effects by reducing in vitro epileptiform activity.
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Affiliation(s)
| | - Brice Mullier
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | | | - Philippe Ghisdal
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Eric Jnoff
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | | | - Dominique Swinnen
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Zara Sands
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Martyn Wood
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
| | - Christian Wolff
- Department of Neuroscience Research, UCB Pharma, Braine l'Alleud, Belgium
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Zhu P, Li J, Zhang L, Liang Z, Tang B, Liao WP, Yi YH, Su T. Development-related aberrations in Kv1.1 α-subunit exert disruptive effects on bioelectrical activities of neurons in a mouse model of fragile X syndrome. Prog Neuropsychopharmacol Biol Psychiatry 2018; 84:140-151. [PMID: 29481897 DOI: 10.1016/j.pnpbp.2018.02.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 02/22/2018] [Accepted: 02/22/2018] [Indexed: 10/18/2022]
Abstract
Kv1.1, a Shaker homologue potassium channel, plays a critical role in homeostatic regulation of neuronal excitability. Aberrations in the functional properties of Kv1.1 have been implicated in several neurological disorders featured by neuronal hyperexcitability. Fragile X syndrome (FXS), the most common form of inherited mental retardation, is characterized by hyperexcitability in neural network and intrinsic membrane properties. The Kv1.1 channel provides an intriguing mechanistic candidate for FXS. We investigated the development-related expression pattern of the Kv1.1 α-subunit by using a Fmr1 knockout (KO) mouse model of FXS. Markedly decreased protein expression of Kv1.1 was found in neonatal and adult stages when compared to age-matched wild-type (WT) mice. Immunohistochemical investigations supported the delayed development-related increases in Kv1.1 expression, especially in CA3 pyramidal neurons. By applying a Kv1.1-specific blocker, dendrotoxin-κ (DTX-κ), we isolated the Kv1.1-mediated currents in the CA3 pyramidal neurons. The isolated DTX-κ-sensitive current of neurons from KO mice exhibited decreased amplitude, lower threshold of activation, and faster recovery from inactivation. The equivalent reduction in potassium current in the WT neurons following application of the appropriate amount of DTX-κ reproduced the enhanced firing abilities of KO neurons, suggesting the Kv1.1 channel as a critical contributor to the hyperexcitability of KO neurons. The role of Kv1.1 in controlling neuronal discharges was further supported by the parallel developmental trajectories of Kv1.1 expression, current amplitude, and discharge impacts, with a significant correlation between the amplitude of Kv1.1-mediated currents and Kv1.1-blocking-induced firing enhancement. These data suggest that the expression of the Kv1.1 α-subunit has a profound pathological relevance to hyperexcitability in FXS, as well as implications for normal development, maintenance, and control of neuronal activities.
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Affiliation(s)
- Pingping Zhu
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China; Department of Neurology, Guangzhou Red Cross Hospital, Medical College, Jinan University, Guangzhou, China
| | - Jialing Li
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Liting Zhang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Zhanrong Liang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Bin Tang
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, 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, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China
| | - Yong-Hong Yi
- Institute of Neuroscience and the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, 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, Guangzhou, China; Key Laboratory of Neurogenetics and Channelopathies of the Ministry of Education of China, Guangzhou, China.
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15
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Kunisawa N, Shimizu S, Kato M, Iha HA, Iwai C, Hashimura M, Ogawa M, Kawaji S, Kawakita K, Abe K, Ohno Y. Pharmacological characterization of nicotine-induced tremor: Responses to anti-tremor and anti-epileptic agents. J Pharmacol Sci 2018; 137:162-169. [PMID: 29945769 DOI: 10.1016/j.jphs.2018.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/18/2018] [Accepted: 05/23/2018] [Indexed: 12/19/2022] Open
Abstract
We previously showed that nicotine evoked kinetic tremor by activating the inferior olive, which is implicated in the pathogenesis of essential tremor, via α7 nicotinic acetylcholine receptors. Here, we evaluated the effects of various anti-tremor and anti-epileptic agents on nicotine-induced tremor in mice to clarify the pharmacological characteristics of nicotine tremor. Drugs effective for essential tremor, propranolol, diazepam and phenobarbital, all significantly inhibited kinetic tremor induced by an intraperitoneal (i.p.) injection of nicotine (1 mg/kg). In contrast, none of the medications for Parkinson's disease, l-DOPA, bromocriptine or trihexyphenidyl, affected the nicotine tremor. Among the anti-epileptic agents examined, valproate, carbamazepine and ethosuximide, significantly inhibited nicotine-induced tremor. In addition, a selective T-type Ca2+ channel blocker, TTA-A2, also suppressed the nicotine tremor. However, neither gabapentin, topiramate, zonisamide nor levetiracetam significantly affected nicotine-induced tremor. The present results show that nicotine-induced tremor resembles essential tremor not only on the neural basis, but also in terms of the pharmacological responses to anti-tremor agents, implying that nicotine-induced tremor can serve as a model for essential tremor. In addition, it is suggested that anti-epileptic agents, which have stimulant actions on the GABAergic system or blocking actions on voltage-gated Na+ channels and T-type Ca2+ channels, can alleviate essential tremor.
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Affiliation(s)
- Naofumi Kunisawa
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Saki Shimizu
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Masaki Kato
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Higor A Iha
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Chihiro Iwai
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Mai Hashimura
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Mizuki Ogawa
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Shohei Kawaji
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Kazuma Kawakita
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Keisuke Abe
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Yukihiro Ohno
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
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Abstract
This review attempts to give a concise and up-to-date overview on the role of potassium channels in epilepsies. Their role can be defined from a genetic perspective, focusing on variants and de novo mutations identified in genetic studies or animal models with targeted, specific mutations in genes coding for a member of the large potassium channel family. In these genetic studies, a demonstrated functional link to hyperexcitability often remains elusive. However, their role can also be defined from a functional perspective, based on dynamic, aggravating, or adaptive transcriptional and posttranslational alterations. In these cases, it often remains elusive whether the alteration is causal or merely incidental. With ∼80 potassium channel types, of which ∼10% are known to be associated with epilepsies (in humans) or a seizure phenotype (in animals), if genetically mutated, a comprehensive review is a challenging endeavor. This goal may seem all the more ambitious once the data on posttranslational alterations, found both in human tissue from epilepsy patients and in chronic or acute animal models, are included. We therefore summarize the literature, and expand only on key findings, particularly regarding functional alterations found in patient brain tissue and chronic animal models.
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Affiliation(s)
- Rüdiger Köhling
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock 18057, Germany
| | - Jakob Wolfart
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock 18057, Germany
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17
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Marsan E, Ishida S, Schramm A, Weckhuysen S, Muraca G, Lecas S, Liang N, Treins C, Pende M, Roussel D, Le Van Quyen M, Mashimo T, Kaneko T, Yamamoto T, Sakuma T, Mahon S, Miles R, Leguern E, Charpier S, Baulac S. Depdc5 knockout rat: A novel model of mTORopathy. Neurobiol Dis 2016; 89:180-9. [PMID: 26873552 DOI: 10.1016/j.nbd.2016.02.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/07/2016] [Indexed: 12/23/2022] Open
Abstract
DEP-domain containing 5 (DEPDC5), encoding a repressor of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway, has recently emerged as a major gene mutated in familial focal epilepsies and focal cortical dysplasia. Here we established a global knockout rat using TALEN technology to investigate in vivo the impact of Depdc5-deficiency. Homozygous Depdc5(-/-) embryos died from embryonic day 14.5 due to a global growth delay. Constitutive mTORC1 hyperactivation was evidenced in the brains and in cultured fibroblasts of Depdc5(-/-) embryos, as reflected by enhanced phosphorylation of its downstream effectors S6K1 and rpS6. Consistently, prenatal treatment with mTORC1 inhibitor rapamycin rescued the phenotype of Depdc5(-/-) embryos. Heterozygous Depdc5(+/-) rats developed normally and exhibited no spontaneous electroclinical seizures, but had altered cortical neuron excitability and firing patterns. Depdc5(+/-) rats displayed cortical cytomegalic dysmorphic neurons and balloon-like cells strongly expressing phosphorylated rpS6, indicative of mTORC1 upregulation, and not observed after prenatal rapamycin treatment. These neuropathological abnormalities are reminiscent of the hallmark brain pathology of human focal cortical dysplasia. Altogether, Depdc5 knockout rats exhibit multiple features of rodent models of mTORopathies, and thus, stand as a relevant model to study their underlying pathogenic mechanisms.
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Affiliation(s)
- Elise Marsan
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Saeko Ishida
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Adrien Schramm
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Sarah Weckhuysen
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Giuseppe Muraca
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Sarah Lecas
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Ning Liang
- Institut Necker-Enfants Malades, CS 61431, Paris, France; INSERM, U1151, F-75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, F-75006 Paris, France
| | - Caroline Treins
- Institut Necker-Enfants Malades, CS 61431, Paris, France; INSERM, U1151, F-75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, F-75006 Paris, France
| | - Mario Pende
- Institut Necker-Enfants Malades, CS 61431, Paris, France; INSERM, U1151, F-75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, F-75006 Paris, France
| | - Delphine Roussel
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Michel Le Van Quyen
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Tomoji Mashimo
- Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University, Suita 565-0871, Japan
| | - Takehito Kaneko
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Takashi Yamamoto
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Hiroshima 739-8526, Japan
| | - Tetsushi Sakuma
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Hiroshima 739-8526, Japan
| | - Séverine Mahon
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Richard Miles
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Eric Leguern
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France; Department of Genetics, Pitié-Salpêtrière Hospital, Public Hospital Network of Paris, Paris, France
| | - Stéphane Charpier
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France
| | - Stéphanie Baulac
- INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France; Department of Genetics, Pitié-Salpêtrière Hospital, Public Hospital Network of Paris, Paris, France.
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Chen SH, Fu SJ, Huang JJ, Tang CY. The episodic ataxia type 1 mutation I262T alters voltage-dependent gating and disrupts protein biosynthesis of human Kv1.1 potassium channels. Sci Rep 2016; 6:19378. [PMID: 26778656 PMCID: PMC4726062 DOI: 10.1038/srep19378] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 12/07/2015] [Indexed: 01/08/2023] Open
Abstract
Voltage-gated potassium (Kv) channels are essential for setting neuronal membrane excitability. Mutations in human Kv1.1 channels are linked to episodic ataxia type 1 (EA1). The EA1-associated mutation I262T was identified from a patient with atypical phenotypes. Although a previous report has characterized its suppression effect, several key questions regarding the impact of the I262T mutation on Kv1.1 as well as other members of the Kv1 subfamily remain unanswered. Herein we show that the dominant-negative effect of I262T on Kv1.1 current expression is not reversed by co-expression with Kvβ1.1 or Kvβ2 subunits. Biochemical examinations indicate that I262T displays enhanced protein degradation and impedes membrane trafficking of Kv1.1 wild-type subunits. I262T appears to be the first EA1 mutation directly associated with impaired protein stability. Further functional analyses demonstrate that I262T changes the voltage-dependent activation and Kvβ1.1-mediated inactivation, uncouples inactivation from activation gating, and decelerates the kinetics of cumulative inactivation of Kv1.1 channels. I262T also exerts similar dominant effects on the gating of Kv1.2 and Kv1.4 channels. Together our data suggest that I262T confers altered channel gating and reduced functional expression of Kv1 channels, which may account for some of the phenotypes of the EA1 patient.
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Affiliation(s)
- Szu-Han Chen
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ssu-Ju Fu
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jing-Jia Huang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chih-Yung Tang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan
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D'Adamo MC, Hasan S, Guglielmi L, Servettini I, Cenciarini M, Catacuzzeno L, Franciolini F. New insights into the pathogenesis and therapeutics of episodic ataxia type 1. Front Cell Neurosci 2015; 9:317. [PMID: 26347608 PMCID: PMC4541215 DOI: 10.3389/fncel.2015.00317] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/30/2015] [Indexed: 11/13/2022] Open
Abstract
Episodic ataxia type 1 (EA1) is a K+channelopathy characterized by a broad spectrum of symptoms. Generally, patients may experience constant myokymia and dramatic episodes of spastic contractions of the skeletal muscles of the head, arms, and legs with loss of both motor coordination and balance. During attacks additional symptoms may be reported such as vertigo, blurred vision, diplopia, nausea, headache, diaphoresis, clumsiness, stiffening of the body, dysarthric speech, and difficulty in breathing. These episodes may be precipitated by anxiety, emotional stress, fatigue, startle response or sudden postural changes. Epilepsy is overrepresented in EA1. The disease is inherited in an autosomal dominant manner, and genetic analysis of several families has led to the discovery of a number of point mutations in the voltage-dependent K+ channel gene KCNA1 (Kv1.1), on chromosome 12p13. To date KCNA1 is the only gene known to be associated with EA1. Functional studies have shown that these mutations impair Kv1.1 channel function with variable effects on channel assembly, trafficking and biophysics. Despite the solid evidence obtained on the molecular mechanisms underlying EA1, how these cause dysfunctions within the central and peripheral nervous systems circuitries remains elusive. This review summarizes the main breakthrough findings in EA1, discusses the neurophysiological mechanisms underlying the disease, current therapies, future challenges and opens a window onto the role of Kv1.1 channels in central nervous system (CNS) and peripheral nervous system (PNS) functions.
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Affiliation(s)
- Maria Cristina D'Adamo
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia Perugia, Italy
| | - Sonia Hasan
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia Perugia, Italy
| | - Luca Guglielmi
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia Perugia, Italy
| | - Ilenio Servettini
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia Perugia, Italy
| | - Marta Cenciarini
- Section of Physiology and Biochemistry, Department of Experimental Medicine, University of Perugia Perugia, Italy
| | - Luigi Catacuzzeno
- Department of Chemistry, Biology and Biotechnology, University of Perugia Perugia, Italy
| | - Fabio Franciolini
- Department of Chemistry, Biology and Biotechnology, University of Perugia Perugia, Italy
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Ohno Y, Shimizu S, Tatara A, Imaoku T, Ishii T, Sasa M, Serikawa T, Kuramoto T. Hcn1 is a tremorgenic genetic component in a rat model of essential tremor. PLoS One 2015; 10:e0123529. [PMID: 25970616 PMCID: PMC4430019 DOI: 10.1371/journal.pone.0123529] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 02/18/2015] [Indexed: 01/12/2023] Open
Abstract
Genetic factors are thought to play a major role in the etiology of essential tremor (ET); however, few genetic changes that induce ET have been identified to date. In the present study, to find genes responsible for the development of ET, we employed a rat model system consisting of a tremulous mutant strain, TRM/Kyo (TRM), and its substrain TRMR/Kyo (TRMR). The TRM rat is homozygous for the tremor (tm) mutation and shows spontaneous tremors resembling human ET. The TRMR rat also carries a homozygous tm mutation but shows no tremor, leading us to hypothesize that TRM rats carry one or more genes implicated in the development of ET in addition to the tm mutation. We used a positional cloning approach and found a missense mutation (c. 1061 C>T, p. A354V) in the hyperpolarization-activated cyclic nucleotide-gated 1 channel (Hcn1) gene. The A354V HCN1 failed to conduct hyperpolarization-activated currents in vitro, implicating it as a loss-of-function mutation. Blocking HCN1 channels with ZD7288 in vivo evoked kinetic tremors in nontremulous TRMR rats. We also found neuronal activation of the inferior olive (IO) in both ZD7288-treated TRMR and non-treated TRM rats and a reduced incidence of tremor in the IO-lesioned TRM rats, suggesting a critical role of the IO in tremorgenesis. A rat strain carrying the A354V mutation alone on a genetic background identical to that of the TRM rats showed no tremor. Together, these data indicate that body tremors emerge when the two mutant loci, tm and Hcn1A354V, are combined in a rat model of ET. In this model, HCN1 channels play an important role in the tremorgenesis of ET. We propose that oligogenic, most probably digenic, inheritance is responsible for the genetic heterogeneity of ET.
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Affiliation(s)
- Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Saki Shimizu
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Ayaka Tatara
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Takuji Imaoku
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Takahiro Ishii
- Department of Physiology and Neurobiology, Graduate School of Medicine, Kyoto University, Kyoto, 606–8501, Japan
| | | | - Tadao Serikawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, 606–8501, Japan
| | - Takashi Kuramoto
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, 606–8501, Japan
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21
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D’Adamo MC, Di Giovanni G, Pessia M. Animal Models of Episodic Ataxia Type 1 (EA1). Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00051-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Serikawa T, Mashimo T, Kuramoro T, Voigt B, Ohno Y, Sasa M. Advances on genetic rat models of epilepsy. Exp Anim 2014; 64:1-7. [PMID: 25312505 PMCID: PMC4329510 DOI: 10.1538/expanim.14-0066] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Considering the suitability of laboratory rats in epilepsy research, we and other groups
have been developing genetic models of epilepsy in this species. After epileptic rats or
seizure-susceptible rats were sporadically found in outbred stocks, the epileptic traits
were usually genetically-fixed by selective breeding. So far, the absence seizure models
GAERS and WAG/Rij, audiogenic seizure models GEPR-3 and GEPR-9, generalized tonic-clonic
seizure models IER, NER and WER, and Canavan-disease related epileptic models TRM and SER
have been established. Dissection of the genetic bases including causative genes in these
epileptic rat models would be a significant step toward understanding epileptogenesis.
N-ethyl-N-nitrosourea (ENU) mutagenesis provides a systematic approach which allowed us to
develop two novel epileptic rat models: heat-induced seizure susceptible (Hiss) rats with
an Scn1a missense mutation and autosomal dominant lateral temporal epilepsy (ADLTE) model
rats with an Lgi1 missense mutation. In addition, we have established episodic ataxia type
1 (EA1) model rats with a Kcna1 missense mutation derived from the ENU-induced rat mutant
stock, and identified a Cacna1a missense mutation in a N-Methyl-N-nitrosourea
(MNU)-induced mutant rat strain GRY, resulting in the discovery of episodic ataxia type 2
(EA2) model rats. Thus, epileptic rat models have been established on the two paths:
‘phenotype to gene’ and ‘gene to phenotype’. In the near future, development of novel
epileptic rat models will be extensively promoted by the use of sophisticated genome
editing technologies.
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Affiliation(s)
- Tadao Serikawa
- Graduate School of Medicine, Kyoto University, Sakyo-ku 606-8501; Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki 569-1094, Japan
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Matilla-Dueñas A, Ashizawa T, Brice A, Magri S, McFarland KN, Pandolfo M, Pulst SM, Riess O, Rubinsztein DC, Schmidt J, Schmidt T, Scoles DR, Stevanin G, Taroni F, Underwood BR, Sánchez I. Consensus paper: pathological mechanisms underlying neurodegeneration in spinocerebellar ataxias. THE CEREBELLUM 2014; 13:269-302. [PMID: 24307138 DOI: 10.1007/s12311-013-0539-y] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Intensive scientific research devoted in the recent years to understand the molecular mechanisms or neurodegeneration in spinocerebellar ataxias (SCAs) are identifying new pathways and targets providing new insights and a better understanding of the molecular pathogenesis in these diseases. In this consensus manuscript, the authors discuss their current views on the identified molecular processes causing or modulating the neurodegenerative phenotype in spinocerebellar ataxias with the common opinion of translating the new knowledge acquired into candidate targets for therapy. The following topics are discussed: transcription dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, RNA toxicity, modulators of neurodegeneration and current therapeutic approaches. Overall point of consensus includes the common vision of neurodegeneration in SCAs as a multifactorial, progressive and reversible process, at least in early stages. Specific points of consensus include the role of the dysregulation of protein folding, transcription, bioenergetics, calcium handling and eventual cell death with apoptotic features of neurons during SCA disease progression. Unresolved questions include how the dysregulation of these pathways triggers the onset of symptoms and mediates disease progression since this understanding may allow effective treatments of SCAs within the window of reversibility to prevent early neuronal damage. Common opinions also include the need for clinical detection of early neuronal dysfunction, for more basic research to decipher the early neurodegenerative process in SCAs in order to give rise to new concepts for treatment strategies and for the translation of the results to preclinical studies and, thereafter, in clinical practice.
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Affiliation(s)
- A Matilla-Dueñas
- Health Sciences Research Institute Germans Trias i Pujol (IGTP), Ctra. de Can Ruti, Camí de les Escoles s/n, Badalona, Barcelona, Spain,
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24
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Tian C, Zhu R, Zhu L, Qiu T, Cao Z, Kang T. Potassium Channels: Structures, Diseases, and Modulators. Chem Biol Drug Des 2013; 83:1-26. [DOI: 10.1111/cbdd.12237] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Chuan Tian
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
- School of Pharmacy; Liaoning University of Traditional Chinese Medicine; Dalian Liaoning 116600 China
| | - Ruixin Zhu
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
| | - Lixin Zhu
- Department of Pediatrics; Digestive Diseases and Nutrition Center; The State University of New York at Buffalo; Buffalo NY 14226 USA
| | - Tianyi Qiu
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
| | - Zhiwei Cao
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
| | - Tingguo Kang
- School of Pharmacy; Liaoning University of Traditional Chinese Medicine; Dalian Liaoning 116600 China
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25
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Shah NH, Aizenman E. Voltage-gated potassium channels at the crossroads of neuronal function, ischemic tolerance, and neurodegeneration. Transl Stroke Res 2013; 5:38-58. [PMID: 24323720 DOI: 10.1007/s12975-013-0297-7] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 09/14/2013] [Accepted: 10/14/2013] [Indexed: 11/29/2022]
Abstract
Voltage-gated potassium (Kv) channels are widely expressed in the central and peripheral nervous system and are crucial mediators of neuronal excitability. Importantly, these channels also actively participate in cellular and molecular signaling pathways that regulate the life and death of neurons. Injury-mediated increased K(+) efflux through Kv2.1 channels promotes neuronal apoptosis, contributing to widespread neuronal loss in neurodegenerative disorders such as Alzheimer's disease and stroke. In contrast, some forms of neuronal activity can dramatically alter Kv2.1 channel phosphorylation levels and influence their localization. These changes are normally accompanied by modifications in channel voltage dependence, which may be neuroprotective within the context of ischemic injury. Kv1 and Kv7 channel dysfunction leads to neuronal hyperexcitability that critically contributes to the pathophysiology of human clinical disorders such as episodic ataxia and epilepsy. This review summarizes the neurotoxic, neuroprotective, and neuroregulatory roles of Kv channels and highlights the consequences of Kv channel dysfunction on neuronal physiology. The studies described in this review thus underscore the importance of normal Kv channel function in neurons and emphasize the therapeutic potential of targeting Kv channels in the treatment of a wide range of neurological diseases.
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Affiliation(s)
- Niyathi Hegde Shah
- Department of Neurobiology, University of Pittsburgh School of Medicine, 3500 Terrace Street, E1456 BST, Pittsburgh, PA, 15261, USA,
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26
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D'Adamo MC, Catacuzzeno L, Di Giovanni G, Franciolini F, Pessia M. K(+) channelepsy: progress in the neurobiology of potassium channels and epilepsy. Front Cell Neurosci 2013; 7:134. [PMID: 24062639 PMCID: PMC3772396 DOI: 10.3389/fncel.2013.00134] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/06/2013] [Indexed: 12/19/2022] Open
Abstract
K(+) channels are important determinants of seizure susceptibility. These membrane proteins, encoded by more than 70 genes, make the largest group of ion channels that fine-tune the electrical activity of neuronal and non-neuronal cells in the brain. Their ubiquity and extremely high genetic and functional diversity, unmatched by any other ion channel type, place K(+) channels as primary targets of genetic variations or perturbations in K(+)-dependent homeostasis, even in the absence of a primary channel defect. It is therefore not surprising that numerous inherited or acquired K(+) channels dysfunctions have been associated with several neurologic syndromes, including epilepsy, which often generate confusion in the classification of the associated diseases. Therefore, we propose to name the K(+) channels defects underlying distinct epilepsies as "K(+) channelepsies," and introduce a new nomenclature (e.g., Kx.y-channelepsy), following the widely used K(+) channel classification, which could be also adopted to easily identify other channelopathies involving Na(+) (e.g., Nav x.y-phenotype), Ca(2+) (e.g., Cav x.y-phenotype), and Cl(-) channels. Furthermore, we discuss novel genetic defects in K(+) channels and associated proteins that underlie distinct epileptic phenotypes in humans, and analyze critically the recent progress in the neurobiology of this disease that has also been provided by investigations on valuable animal models of epilepsy. The abundant and varied lines of evidence discussed here strongly foster assessments for variations in genes encoding for K(+) channels and associated proteins in patients with idiopathic epilepsy, provide new avenues for future investigations, and highlight these proteins as critical pharmacological targets.
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Key Words
- Potassium channels: [Kv1, Kv2, Kv3, Kv4, Kv8, Kv11(HERG), KCa1.1, Kvβ1, Kvβ2, KChIP LGI1, Kir1-Kir7 (GIRK, KATP)]
- autism–epilepsy
- channelopathies
- temporal lobe epilepsy
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Affiliation(s)
- Maria Cristina D'Adamo
- Faculty of Medicine, Section of Human Physiology, Department of Internal Medicine, University of Perugia Perugia, Italy ; Istituto Euro Mediterraneo di Scienza e Tecnologia, IEMEST Palermo, Italy
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Myokymia and neuromyotonia in veterinary medicine: a comparison with peripheral nerve hyperexcitability syndrome in humans. Vet J 2013; 197:153-62. [PMID: 23583699 DOI: 10.1016/j.tvjl.2013.03.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/12/2013] [Accepted: 03/04/2013] [Indexed: 01/17/2023]
Abstract
Involuntary muscle hyperactivity can result from muscle or peripheral nerve hyperexcitability or central nervous system dysfunction. In humans, diseases causing hyperexcitability of peripheral nerves are grouped together under the term 'peripheral nerve hyperexcitability' (PNH). Hyperexcitability of the peripheral motor nerve can result into five different phenotypic main variants, i.e. fasciculations, myokymia, neuromyotonia, cramps and tetany, each with their own clinical and electromyographic characteristics. This review focuses on the most commonly described expressions of PNH in veterinary medicine, i.e. myokymia and neuromyotonia, in particular in young Jack Russell terriers. Data from 58 veterinary cases with generalized myokymia and neuromyotonia were analyzed, including unpublished treatment and follow-up data on eight Jack Russell terriers from a previous study and seven additional Jack Russell terriers. A dysfunction of the potassium channel or its associated proteins has been found in many human syndromes characterized by PNH, in particular in generalized myokymia and neuromyotonia, and is suspected to occur in veterinary medicine. Potential pathomechanisms of potassium channel dysfunction leading to signs of PNH are broad and include genetic mutations, antibody-mediated attack or ion channel maldistribution due to axonal degeneration or demyelination. A more accurate classification of the different PNH syndromes will facilitate a more rapid diagnosis and guide further research into natural occurring PNH in animals.
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