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Spekker E, Nagy-Grócz G, Vécsei L. Ion Channel Disturbances in Migraine Headache: Exploring the Potential Role of the Kynurenine System in the Context of the Trigeminovascular System. Int J Mol Sci 2023; 24:16574. [PMID: 38068897 PMCID: PMC10706278 DOI: 10.3390/ijms242316574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/13/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023] Open
Abstract
Migraine is a primary headache disorder, which is an enormous burden to the healthcare system. While some aspects of the pathomechanism of migraines remain unknown, the most accepted theory is that activation and sensitization of the trigeminovascular system are essential during migraine attacks. In recent decades, it has been suggested that ion channels may be important participants in the pathogenesis of migraine. Numerous ion channels are expressed in the peripheral and central nervous systems, including the trigeminovascular system, affecting neuron excitability, synaptic energy homeostasis, inflammatory signaling, and pain sensation. Dysfunction of ion channels could result in neuronal excitability and peripheral or central sensitization. This narrative review covers the current understanding of the biological mechanisms leading to activation and sensitization of the trigeminovascular pain pathway, with a focus on recent findings on ion channel activation and modulation. Furthermore, we focus on the kynurenine pathway since this system contains kynurenic acid, which is an endogenous glutamate receptor antagonist substance, and it has a role in migraine pathophysiology.
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Affiliation(s)
| | - Gábor Nagy-Grócz
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, H-6725 Szeged, Hungary;
- Faculty of Health Sciences and Social Studies, University of Szeged, H-6726 Szeged, Hungary
- Preventive Health Sciences Research Group, Incubation Competence Centre of the Centre of Excellence for Interdisciplinary Research, Development and Innovation of the University of Szeged, H-6725 Szeged, Hungary
| | - László Vécsei
- Department of Neurology, Faculty of Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, H-6725 Szeged, Hungary;
- HUN-REN-SZTE Neuroscience Research Group, University of Szeged, H-6725 Szeged, Hungary
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Gosalia H, Karsan N, Goadsby PJ. Genetic Mechanisms of Migraine: Insights from Monogenic Migraine Mutations. Int J Mol Sci 2023; 24:12697. [PMID: 37628876 PMCID: PMC10454024 DOI: 10.3390/ijms241612697] [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: 07/06/2023] [Revised: 08/01/2023] [Accepted: 08/06/2023] [Indexed: 08/27/2023] Open
Abstract
Migraine is a disabling neurological disorder burdening patients globally. Through the increasing development of preclinical and clinical experimental migraine models, advancing appreciation of the extended clinical phenotype, and functional neuroimaging studies, we can further our understanding of the neurobiological basis of this highly disabling condition. Despite increasing understanding of the molecular and chemical architecture of migraine mechanisms, many areas require further investigation. Research over the last three decades has suggested that migraine has a strong genetic basis, based on the positive family history in most patients, and this has steered exploration into possibly implicated genes. In recent times, human genome-wide association studies and rodent genetic migraine models have facilitated our understanding, but most migraine seems polygenic, with the monogenic migraine mutations being considerably rarer, so further large-scale studies are required to elucidate fully the genetic underpinnings of migraine and the translation of these to clinical practice. The monogenic migraine mutations cause severe aura phenotypes, amongst other symptoms, and offer valuable insights into the biology of aura and the relationship between migraine and other conditions, such as vascular disease and sleep disorders. This review will provide an outlook of what is known about some monogenic migraine mutations, including familial hemiplegic migraine, familial advanced sleep-phase syndrome, and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.
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Affiliation(s)
- Helin Gosalia
- Headache Group, The Wolfson Sensory, Pain and Rehabilitation Centre, NIHR King’s Clinical Research Facility, & SLaM Biomedical Research Centre, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London SE5 9PJ, UK; (H.G.); (N.K.)
| | - Nazia Karsan
- Headache Group, The Wolfson Sensory, Pain and Rehabilitation Centre, NIHR King’s Clinical Research Facility, & SLaM Biomedical Research Centre, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London SE5 9PJ, UK; (H.G.); (N.K.)
| | - Peter J. Goadsby
- Headache Group, The Wolfson Sensory, Pain and Rehabilitation Centre, NIHR King’s Clinical Research Facility, & SLaM Biomedical Research Centre, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London SE5 9PJ, UK; (H.G.); (N.K.)
- Department of Neurology, University of California, Los Angeles, CA 90095, USA
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Pijpers JA, Au PYB, Weeke LC, Vein AA, Smit LS, Vilan A, Jacobs E, de Vries LS, Steggerda SJ, Cilio MR, Carapancea E, Cornet MC, Appendino JP, Peeters-Scholte CMPCD. Early recognition of characteristic conventional and amplitude-integrated EEG patterns of seizures in SCN2A and KCNQ3-related epilepsy in neonates. Seizure 2023; 110:212-219. [PMID: 37429183 DOI: 10.1016/j.seizure.2023.06.016] [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: 02/18/2023] [Revised: 05/30/2023] [Accepted: 06/19/2023] [Indexed: 07/12/2023] Open
Abstract
PURPOSE Early recognition of seizures in neonates secondary to pathogenic variants in potassium or sodium channel coding genes is crucial, as these seizures are often resistant to commonly used anti-seizure medications but respond well to sodium channel blockers. Recently, a characteristic ictal amplitude-integrated electroencephalogram (aEEG) pattern was described in neonates with KCNQ2-related epilepsy. We report a similar aEEG pattern in seizures caused by SCN2A- and KCNQ3-pathogenic variants, as well as conventional EEG (cEEG) descriptions. METHODS International multicentre descriptive study, reporting clinical characteristics, aEEG and cEEG findings of 13 neonates with seizures due to pathogenic SCN2A- and KCNQ3-variants. As a comparison group, aEEGs and cEEGs of neonates with seizures due to hypoxic-ischemic encephalopathy (n = 117) and other confirmed genetic causes affecting channel function (n = 55) were reviewed. RESULTS In 12 out of 13 patients, the aEEG showed a characteristic sequence of brief onset with a decrease, followed by a quick rise, and then postictal amplitude attenuation. This pattern correlated with bilateral EEG onset attenuation, followed by rhythmic discharges ending in several seconds of post-ictal amplitude suppression. Apart from patients with KCNQ2-related epilepsy, none of the patients in the comparison groups had a similar aEEG or cEEG pattern. DISCUSSION Seizures in SCN2A- and KCNQ3-related epilepsy in neonates can usually be recognized by a characteristic ictal aEEG pattern, previously reported only in KCNQ2-related epilepsy, extending this unique feature to other channelopathies. Awareness of this pattern facilitates the prompt initiation of precision treatment with sodium channel blockers even before genetic results are available.
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Affiliation(s)
- Judith A Pijpers
- Departments of Neurology and Clinical Neurophysiology, Leiden University Medical Center, PO Box 9600, Leiden 2300 RC, the Netherlands.
| | - Ping Yee Billie Au
- Departments of Medical Genetics, Cumming School of Medicine, University of Calgary, Canada
| | - Lauren C Weeke
- Departments of Neonatology, Erasmus Medical Center, the Netherlands
| | - Alla A Vein
- Departments of Neurology and Clinical Neurophysiology, Leiden University Medical Center, PO Box 9600, Leiden 2300 RC, the Netherlands
| | - Liesbeth S Smit
- Departments of Neonatology, Erasmus Medical Center, the Netherlands; Departments of Neurology, Erasmus Medical Center, the Netherlands
| | - Ana Vilan
- Department of Neonatology, Centro Hospitalar Universitário São João, Faculty of Medicine, University of Porto, Portugal
| | - Elke Jacobs
- Departments of Neurology, Erasmus Medical Center, the Netherlands
| | - Linda S de Vries
- Departments of Neonatology, Leiden University Medical Center, the Netherlands
| | - Sylke J Steggerda
- Departments of Neonatology, Leiden University Medical Center, the Netherlands
| | - Maria Roberta Cilio
- Division of Pediatric Neurology, Department of Pediatrics, Catholic University of Louvain, Brussels, Belgium
| | - Evelina Carapancea
- Division of Pediatric Neurology, Department of Pediatrics, Catholic University of Louvain, Brussels, Belgium
| | - Marie-Coralie Cornet
- Division of Neonatology, Department of Pediatrics, Benioff Children's Hospital, University of California, San Francisco, CA, USA
| | - Juan P Appendino
- Departments of Pediatric Neurology, Cumming School of Medicine, University of Calgary, Canada
| | - Cacha M P C D Peeters-Scholte
- Departments of Neurology and Clinical Neurophysiology, Leiden University Medical Center, PO Box 9600, Leiden 2300 RC, the Netherlands
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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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Garrido JJ. Contribution of Axon Initial Segment Structure and Channels to Brain Pathology. Cells 2023; 12:cells12081210. [PMID: 37190119 DOI: 10.3390/cells12081210] [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: 04/01/2023] [Revised: 04/17/2023] [Accepted: 04/20/2023] [Indexed: 05/17/2023] Open
Abstract
Brain channelopathies are a group of neurological disorders that result from genetic mutations affecting ion channels in the brain. Ion channels are specialized proteins that play a crucial role in the electrical activity of nerve cells by controlling the flow of ions such as sodium, potassium, and calcium. When these channels are not functioning properly, they can cause a wide range of neurological symptoms such as seizures, movement disorders, and cognitive impairment. In this context, the axon initial segment (AIS) is the site of action potential initiation in most neurons. This region is characterized by a high density of voltage-gated sodium channels (VGSCs), which are responsible for the rapid depolarization that occurs when the neuron is stimulated. The AIS is also enriched in other ion channels, such as potassium channels, that play a role in shaping the action potential waveform and determining the firing frequency of the neuron. In addition to ion channels, the AIS contains a complex cytoskeletal structure that helps to anchor the channels in place and regulate their function. Therefore, alterations in this complex structure of ion channels, scaffold proteins, and specialized cytoskeleton may also cause brain channelopathies not necessarily associated with ion channel mutations. This review will focus on how the AISs structure, plasticity, and composition alterations may generate changes in action potentials and neuronal dysfunction leading to brain diseases. AIS function alterations may be the consequence of voltage-gated ion channel mutations, but also may be due to ligand-activated channels and receptors and AIS structural and membrane proteins that support the function of voltage-gated ion channels.
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Affiliation(s)
- Juan José Garrido
- Instituto Cajal, CSIC, 28002 Madrid, Spain
- Alzheimer's Disease and Other Degenerative Dementias, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), 28002 Madrid, Spain
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Involvement of Potassium Channel Signalling in Migraine Pathophysiology. Pharmaceuticals (Basel) 2023; 16:ph16030438. [PMID: 36986537 PMCID: PMC10057509 DOI: 10.3390/ph16030438] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/28/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023] Open
Abstract
Migraine is a primary headache disorder ranked as the leading cause of years lived with disability among individuals younger than 50 years. The aetiology of migraine is complex and might involve several molecules of different signalling pathways. Emerging evidence implicates potassium channels, predominantly ATP-sensitive potassium (KATP) channels and large (big) calcium-sensitive potassium (BKCa) channels in migraine attack initiation. Basic neuroscience revealed that stimulation of potassium channels activated and sensitized trigeminovascular neurons. Clinical trials showed that administration of potassium channel openers caused headache and migraine attack associated with dilation of cephalic arteries. The present review highlights the molecular structure and physiological function of KATP and BKCa channels, presents recent insights into the role of potassium channels in migraine pathophysiology, and discusses possible complementary effects and interdependence of potassium channels in migraine attack initiation.
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A bivalent remipede toxin promotes calcium release via ryanodine receptor activation. Nat Commun 2023; 14:1036. [PMID: 36823422 PMCID: PMC9950431 DOI: 10.1038/s41467-023-36579-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 02/07/2023] [Indexed: 02/25/2023] Open
Abstract
Multivalent ligands of ion channels have proven to be both very rare and highly valuable in yielding unique insights into channel structure and pharmacology. Here, we describe a bivalent peptide from the venom of Xibalbanus tulumensis, a troglobitic arthropod from the enigmatic class Remipedia, that causes persistent calcium release by activation of ion channels involved in muscle contraction. The high-resolution solution structure of φ-Xibalbin3-Xt3a reveals a tandem repeat arrangement of inhibitor-cysteine knot (ICK) domains previously only found in spider venoms. The individual repeats of Xt3a share sequence similarity with a family of scorpion toxins that target ryanodine receptors (RyR). Single-channel electrophysiology and quantification of released Ca2+ stores within skinned muscle fibers confirm Xt3a as a bivalent RyR modulator. Our results reveal convergent evolution of RyR targeting toxins in remipede and scorpion venoms, while the tandem-ICK repeat architecture is an evolutionary innovation that is convergent with toxins from spider venoms.
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Gray MM, Naik A, Ebner TJ, Carter RE. Altered brain state during episodic dystonia in tottering mice decouples primary motor cortex from limb kinematics. DYSTONIA 2023; 2:10974. [PMID: 37800168 PMCID: PMC10554815 DOI: 10.3389/dyst.2023.10974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Episodic Ataxia Type 2 (EA2) is a rare neurological disorder caused by a mutation in the CACNA1A gene, encoding the P/Q-type voltage-gated Ca2+ channel important for neurotransmitter release. Patients with this channelopathy exhibit both cerebellar and cerebral pathologies, suggesting the condition affects both regions. The tottering (tg/tg) mouse is the most commonly used EA2 model due to an orthologous mutation in the cacna1a gene. The tg/tg mouse has three prominent behavioral phenotypes: a dramatic episodic dystonia; absence seizures with generalized spike and wave discharges (GSWDs); and mild ataxia. We previously observed a novel brain state, transient low-frequency oscillations (LFOs) in the cerebellum and cerebral cortex under anesthesia. In this study, we examine the relationships among the dystonic attack, GSWDs, and LFOs in the cerebral cortex. Previous studies characterized LFOs in the motor cortex of anesthetized tg/tg mice using flavoprotein autofluorescence imaging testing the hypothesis that LFOs provide a mechanism for the paroxysmal dystonia. We sought to obtain a more direct understanding of motor cortex (M1) activity during the dystonic episodes. Using two-photon Ca2+ imaging to investigate neuronal activity in M1 before, during, and after the dystonic attack, we show that there is not a significant change in the activity of M1 neurons from baseline through the attack. We also conducted simultaneous, multi-electrode recordings to further understand how M1 cellular activity and local field potentials change throughout the progression of the dystonic attack. Neither putative pyramidal nor inhibitory interneuron firing rate changed during the dystonic attack. However, we did observe a near complete loss of GSWDs during the dystonic attack in M1. Finally, using spike triggered averaging to align simultaneously recorded limb kinematics to the peak Ca2+ response, and vice versa, revealed a reduction in the spike triggered average during the dystonic episodes. Both the loss of GSWDs and the reduction in the coupling suggest that, during the dystonic attack, M1 is effectively decoupled from other structures. Overall, these results indicate that the attack is not initiated or controlled in M1, but elsewhere in the motor circuitry. The findings also highlight that LFOs, GSWDs, and dystonic attacks represent three brain states in tg/tg mice.
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Affiliation(s)
- Madelyn M Gray
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Anant Naik
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
| | - Russell E Carter
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, United States
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Salpietro V, Galassi Deforie V, Efthymiou S, O'Connor E, Marcé‐Grau A, Maroofian R, Striano P, Zara F, Morrow MM, Reich A, Blevins A, Sala‐Coromina J, Accogli A, Fortuna S, Alesandrini M, Au PYB, Singhal NS, Cogne B, Isidor B, Hanna MG, Macaya A, Kullmann DM, Houlden H, Männikkö R. De novo KCNA6 variants with attenuated K V 1.6 channel deactivation in patients with epilepsy. Epilepsia 2023; 64:443-455. [PMID: 36318112 PMCID: PMC10108282 DOI: 10.1111/epi.17455] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 10/31/2022] [Accepted: 10/31/2022] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Mutations in the genes encoding neuronal ion channels are a common cause of Mendelian neurological diseases. We sought to identify novel de novo sequence variants in cases with early infantile epileptic phenotypes and neurodevelopmental anomalies. METHODS Following clinical diagnosis, we performed whole exome sequencing of the index cases and their parents. Identified channel variants were expressed in Xenopus oocytes and their functional properties assessed using two-electrode voltage clamp. RESULTS We identified novel de novo variants in KCNA6 in four unrelated individuals variably affected with neurodevelopmental disorders and seizures with onset in the first year of life. Three of the four identified mutations affect the pore-lining S6 α-helix of KV 1.6. A prominent finding of functional characterization in Xenopus oocytes was that the channel variants showed only minor effects on channel activation but slowed channel closure and shifted the voltage dependence of deactivation in a hyperpolarizing direction. Channels with a mutation affecting the S6 helix display dominant effects on channel deactivation when co-expressed with wild-type KV 1.6 or KV 1.1 subunits. SIGNIFICANCE This is the first report of de novo nonsynonymous variants in KCNA6 associated with neurological or any clinical features. Channel variants showed a consistent effect on channel deactivation, slowing the rate of channel closure following normal activation. This specific gain-of-function feature is likely to underlie the neurological phenotype in our patients. Our data highlight KCNA6 as a novel channelopathy gene associated with early infantile epileptic phenotypes and neurodevelopmental anomalies.
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Affiliation(s)
- Vincenzo Salpietro
- Department of Neuromuscular DiseaseUCL Institute of Neurology, University College LondonLondonUK
- Department of Biotechnological and Applied Clinical Sciences (DISCAB)University of L'AquilaL'AquilaItaly
| | | | - Stephanie Efthymiou
- Department of Neuromuscular DiseaseUCL Institute of Neurology, University College LondonLondonUK
| | - Emer O'Connor
- Department of Neuromuscular DiseaseUCL Institute of Neurology, University College LondonLondonUK
| | - Anna Marcé‐Grau
- Department of Paediatric Neurology, University Hospital Vall d'HebronUniversitat Autònoma de BarcelonaBarcelonaSpain
| | - Reza Maroofian
- Department of Neuromuscular DiseaseUCL Institute of Neurology, University College LondonLondonUK
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI)University of Genoa16124 GenoaItaly
- Unit of Pediatric NeurologyIRCCS, Istituto “Giannina Gaslini”Genoa 16123Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI)University of Genoa16124 GenoaItaly
- Medical Genetics UnitIRCCS, Istituto “Giannina Gaslini”Genoa 16123Italy
| | | | | | | | | | - Júlia Sala‐Coromina
- Department of Paediatric Neurology, University Hospital Vall d'HebronUniversitat Autònoma de BarcelonaBarcelonaSpain
| | - Andrea Accogli
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI)University of Genoa16124 GenoaItaly
- Medical Genetics UnitIRCCS, Istituto “Giannina Gaslini”Genoa 16123Italy
| | | | - Marie Alesandrini
- Neuropediatrics UnitCentre Hospitalier Universitaire NantesNantesFrance
| | - P. Y. Billie Au
- Department of Medical Genetics, Alberta Children's Hospital Research Institute, Cumming School of MedicineUniversity of CalgaryAlbertaCalgaryCanada
| | - Nilika Shah Singhal
- Departments of Neurology and Pediatrics, UCSF Benioff Children's HospitalUniversity of CaliforniaCaliforniaSan FranciscoUSA
| | - Benjamin Cogne
- Centre Hospitalier Universitaire NantesService de Génétique MédicaleNantesFrance
- Université de Nantes, CNRS, INSERML'Institut du ThoraxNantesFrance
| | - Bertrand Isidor
- Centre Hospitalier Universitaire NantesService de Génétique MédicaleNantesFrance
- Université de Nantes, CNRS, INSERML'Institut du ThoraxNantesFrance
| | - Michael G. Hanna
- Department of Neuromuscular DiseaseUCL Institute of Neurology, University College LondonLondonUK
- Queen Square Centre for Neuromuscular DiseasesNational Hospital for Neurology and NeurosurgeryLondonUK
| | - Alfons Macaya
- Department of Paediatric Neurology, University Hospital Vall d'HebronUniversitat Autònoma de BarcelonaBarcelonaSpain
| | - Dimitri M. Kullmann
- Department of Clinical and Experimental EpilepsyUCL Institute of Neurology, University College LondonLondonUK
| | - Henry Houlden
- Department of Neuromuscular DiseaseUCL Institute of Neurology, University College LondonLondonUK
| | - Roope Männikkö
- Department of Neuromuscular DiseaseUCL Institute of Neurology, University College LondonLondonUK
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Cancer as a Channelopathy—Appreciation of Complimentary Pathways Provides a Different Perspective for Developing Treatments. Cancers (Basel) 2022; 14:cancers14194627. [PMID: 36230549 PMCID: PMC9562872 DOI: 10.3390/cancers14194627] [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: 07/26/2022] [Revised: 09/17/2022] [Accepted: 09/21/2022] [Indexed: 12/15/2022] Open
Abstract
Simple Summary While improvements in technology have improved our ability to treat many forms of cancer when diagnosed at an early stage of the disease, the ability to improve survival and quality of life for patients with late stage disease has been limited, largely due to the ability of cancer cells to evade destruction when treatments block preferred paths for survival. Here, we review the role that ions and ion channels play in normal cell function, the development of disease and their role in the life and death of a cell. It is hoped that viewing cancer from the perspective of altered ion channel expression and ion balance may provide a novel approach for developing more effective treatments for this devastating disease. Abstract Life depends upon the ability of cells to evaluate and adapt to a constantly changing environment and to maintain internal stability to allow essential biochemical reactions to occur. Ions and ion channels play a crucial role in this process and are essential for survival. Alterations in the expression of the transmembrane proteins responsible for maintaining ion balance that occur as a result of mutations in the genetic code or in response to iatrogenically induced changes in the extracellular environment is a characteristic feature of oncogenesis and identifies cancer as one of a constellation of diseases known as channelopathies. The classification of cancer as a channelopathy provides a different perspective for viewing the disease. Potentially, it may expand opportunities for developing novel ways to affect or reverse the deleterious changes that underlie establishing and sustaining disease and developing tolerance to therapeutic attempts at treatment. The role of ions and ion channels and their interactions in the cell’s ability to maintain ionic balance, homeostasis, and survival are reviewed and possible approaches that mitigate gain or loss of ion channel function to contribute to new or enhance existing cancer therapies are discussed.
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Tchoe Y, Lee J, Liu R, Bourhis AM, Vatsyayan R, Tonsfeldt KJ, Dayeh SA. Considerations and recent advances in nanoscale interfaces with neuronal and cardiac networks. APPLIED PHYSICS REVIEWS 2021; 8:041317. [PMID: 34868443 PMCID: PMC8596389 DOI: 10.1063/5.0052666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 10/07/2021] [Indexed: 05/21/2023]
Abstract
Nanoscale interfaces with biological tissue, principally made with nanowires (NWs), are envisioned as minimally destructive to the tissue and as scalable tools to directly transduce the electrochemical activity of a neuron at its finest resolution. This review lays the foundations for understanding the material and device considerations required to interrogate neuronal activity at the nanoscale. We first discuss the electrochemical nanoelectrode-neuron interfaces and then present new results concerning the electrochemical impedance and charge injection capacities of millimeter, micrometer, and nanometer scale wires with Pt, PEDOT:PSS, Si, Ti, ITO, IrO x , Ag, and AgCl materials. Using established circuit models for NW-neuron interfaces, we discuss the impact of having multiple NWs interfacing with a single neuron on the amplitude and temporal characteristics of the recorded potentials. We review state of the art advances in nanoelectrode-neuron interfaces, the standard control experiments to investigate their electrophysiological behavior, and present recent high fidelity recordings of intracellular potentials obtained with ultrasharp NWs developed in our laboratory that naturally permeate neuronal cell bodies. Recordings from arrays and individually addressable electrically shorted NWs are presented, and the long-term stability of intracellular recording is discussed and put in the context of established techniques. Finally, a perspective on future research directions and applications is presented.
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Affiliation(s)
- Youngbin Tchoe
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, USA
| | - Jihwan Lee
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, USA
| | - Ren Liu
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, USA
| | - Andrew M. Bourhis
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, USA
| | - Ritwik Vatsyayan
- Integrated Electronics and Biointerfaces Laboratory, Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, USA
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12
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Sinha M, Narayanan R. Active Dendrites and Local Field Potentials: Biophysical Mechanisms and Computational Explorations. Neuroscience 2021; 489:111-142. [PMID: 34506834 PMCID: PMC7612676 DOI: 10.1016/j.neuroscience.2021.08.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 10/27/2022]
Abstract
Neurons and glial cells are endowed with membranes that express a rich repertoire of ion channels, transporters, and receptors. The constant flux of ions across the neuronal and glial membranes results in voltage fluctuations that can be recorded from the extracellular matrix. The high frequency components of this voltage signal contain information about the spiking activity, reflecting the output from the neurons surrounding the recording location. The low frequency components of the signal, referred to as the local field potential (LFP), have been traditionally thought to provide information about the synaptic inputs that impinge on the large dendritic trees of various neurons. In this review, we discuss recent computational and experimental studies pointing to a critical role of several active dendritic mechanisms that can influence the genesis and the location-dependent spectro-temporal dynamics of LFPs, spanning different brain regions. We strongly emphasize the need to account for the several fast and slow dendritic events and associated active mechanisms - including gradients in their expression profiles, inter- and intra-cellular spatio-temporal interactions spanning neurons and glia, heterogeneities and degeneracy across scales, neuromodulatory influences, and activitydependent plasticity - towards gaining important insights about the origins of LFP under different behavioral states in health and disease. We provide simple but essential guidelines on how to model LFPs taking into account these dendritic mechanisms, with detailed methodology on how to account for various heterogeneities and electrophysiological properties of neurons and synapses while studying LFPs.
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Affiliation(s)
- Manisha Sinha
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India.
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13
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Abstract
Already for centuries, humankind is driven to understand the physiological and pathological mechanisms that occur in our brains. Today, we know that ion channels play an essential role in the regulation of neural processes and control many functions of the central nervous system. Ion channels present a diverse group of membrane-spanning proteins that allow ions to penetrate the insulating cell membrane upon opening of their channel pores. This regulated ion permeation results in different electrical and chemical signals that are necessary to maintain physiological excitatory and inhibitory processes in the brain. Therefore, it is no surprise that disturbances in the functions of cerebral ion channels can result in a plethora of neurological disorders, which present a tremendous health care burden for our current society. The identification of ion channel-related brain disorders also fuel the research into the roles of ion channel proteins in various brain states. In the last decade, mounting evidence has been collected that indicates a pivotal role for transient receptor potential (TRP) ion channels in the development and various physiological functions of the central nervous system. For instance, TRP channels modulate neurite growth, synaptic plasticity and integration, and are required for neuronal survival. Moreover, TRP channels are involved in numerous neurological disorders. TRPM3 belongs to the melastatin subfamily of TRP channels and represents a non-selective cation channel that can be activated by several different stimuli, including the neurosteroid pregnenolone sulfate, osmotic pressures and heat. The channel is best known as a peripheral nociceptive ion channel that participates in heat sensation. However, recent research identifies TRPM3 as an emerging new player in the brain. In this review, we summarize the available data regarding the roles of TRPM3 in the brain, and correlate these data with the neuropathological processes in which this ion channel may be involved.
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Affiliation(s)
- Katharina Held
- Laboratory of Endometrium, Endometriosis and Reproductive Medicine, Department of Development and Regeneration, KU Leuven, Leuven, Belgium
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine and VIB-KU Leuven Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
| | - Balázs István Tóth
- Laboratory of Cellular and Molecular Physiology, Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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14
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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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15
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Seenivasan P, Narayanan R. Efficient phase coding in hippocampal place cells. PHYSICAL REVIEW RESEARCH 2020; 2:033393. [PMID: 32984841 PMCID: PMC7116119 DOI: 10.1103/physrevresearch.2.033393] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Neural codes have been postulated to build efficient representations of the external world. The hippocampus, an encoding system, employs neuronal firing rates and spike phases to encode external space. Although the biophysical origin of such codes is at a single neuronal level, the role of neural components in efficient coding is not understood. The complexity of this problem lies in the dimensionality of the parametric space encompassing neural components, and is amplified by the enormous biological heterogeneity observed in each parameter. A central question that spans encoding systems therefore is how neurons arrive at efficient codes in the face of widespread biological heterogeneities. To answer this, we developed a conductance-based spiking model for phase precession, a phase code of external space exhibited by hippocampal place cells. Our model accounted for several experimental observations on place cell firing and electrophysiology: the emergence of phase precession from exact spike timings of conductance-based models with neuron-specific ion channels and receptors; biological heterogeneities in neural components and excitability; the emergence of subthreshold voltage ramp, increased firing rate, enhanced theta power within the place field; a signature reduction in extracellular theta frequency compared to its intracellular counterpart; and experience-dependent asymmetry in firing-rate profile. We formulated phase-coding efficiency, using Shannon's information theory, as an information maximization problem with spike phase as the response and external space within a single place field as the stimulus. We employed an unbiased stochastic search spanning an 11-dimensional neural space, involving thousands of iterations that accounted for the biophysical richness and neuron-to-neuron heterogeneities. We found a small subset of models that exhibited efficient spatial information transfer through the phase code, and investigated the distinguishing features of this subpopulation at the parametric and functional scales. At the parametric scale, which spans the molecular components that defined the neuron, several nonunique parametric combinations with weak pairwise correlations yielded models with similar high phase-coding efficiency. Importantly, placing additional constraints on these models in terms of matching other aspects of hippocampal neural responses did not hamper parametric degeneracy. We provide quantitative evidence demonstrating this parametric degeneracy to be a consequence of a many-to-one relationship between the different parameters and phase-coding efficiency. At the functional scale, involving the cellular-scale neural properties, our analyses revealed an important higher-order constraint that was exclusive to models exhibiting efficient phase coding. Specifically, we found a counterbalancing negative correlation between neuronal gain and the strength of external synaptic inputs as a critical functional constraint for the emergence of efficient phase coding. These observations implicate intrinsic neural properties as important contributors in effectuating such counterbalance, which can be achieved by recruiting nonunique parametric combinations. Finally, we show that a change in afferent statistics, manifesting as input asymmetry onto these neuronal models, induced an adaptive shift in the phase code that preserved its efficiency. Together, our analyses unveil parametric degeneracy as a mechanism to harness widespread neuron-to-neuron heterogeneity towards accomplishing stable and efficient encoding, provided specific higher-order functional constraints on the relationship of neural gain to external inputs are satisfied.
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16
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Al-Sabi A, Daly D, Rooney M, Hughes C, Kinsella GK, Kaza SK, Nolan K, Oliver Dolly J. Development of a selective inhibitor for Kv1.1 channels prevalent in demyelinated nerves. Bioorg Chem 2020; 100:103918. [PMID: 32428746 DOI: 10.1016/j.bioorg.2020.103918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 03/23/2020] [Accepted: 05/05/2020] [Indexed: 11/19/2022]
Abstract
Members of the voltage-gated K+ channel subfamily (Kv1), involved in regulating transmission between neurons or to muscles, are associated with human diseases and, thus, putative targets for neurotherapeutics. This applies especially to those containing Kv1.1 α subunits which become prevalent in murine demyelinated axons and appear abnormally at inter-nodes, underlying the perturbed propagation of nerve signals. To overcome this dysfunction, akin to the consequential debilitation in multiple sclerosis (MS), small inhibitors were sought that are selective for the culpable hyper-polarising K+ currents. Herein, we report a new semi-podand - compound 3 - that was designed based on the modelling of its interactions with the extracellular pore region in a deduced Kv1.1 channel structure. After synthesis, purification, and structural characterisation, compound 3 was found to potently (IC50 = 8 µM) and selectively block Kv1.1 and 1.6 channels. The tested compound showed no apparent effect on native Nav and Cav channels expressed in F-11 cells. Compound 3 also extensively and selectively inhibited MS-related Kv1.1 homomer but not the brain native Kv1.1- or 1.6-containing channels. These collective findings highlight the therapeutic potential of compound 3 to block currents mediated by Kv1.1 channels enriched in demyelinated central neurons.
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Affiliation(s)
- Ahmed Al-Sabi
- College of Engineering and Technology, American University of the Middle East, Kuwait; International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Declan Daly
- School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Myles Rooney
- School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Cian Hughes
- School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Gemma K Kinsella
- School of Food Science and Environmental Health, College of Sciences and Health, Technological University Dublin, Cathal Brugha Street, Dublin 1, Ireland
| | - Seshu K Kaza
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
| | - Kieran Nolan
- School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland.
| | - J Oliver Dolly
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin 9, Ireland
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17
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Rathour RK, Narayanan R. Degeneracy in hippocampal physiology and plasticity. Hippocampus 2019; 29:980-1022. [PMID: 31301166 PMCID: PMC6771840 DOI: 10.1002/hipo.23139] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 05/27/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022]
Abstract
Degeneracy, defined as the ability of structurally disparate elements to perform analogous function, has largely been assessed from the perspective of maintaining robustness of physiology or plasticity. How does the framework of degeneracy assimilate into an encoding system where the ability to change is an essential ingredient for storing new incoming information? Could degeneracy maintain the balance between the apparently contradictory goals of the need to change for encoding and the need to resist change towards maintaining homeostasis? In this review, we explore these fundamental questions with the mammalian hippocampus as an example encoding system. We systematically catalog lines of evidence, spanning multiple scales of analysis that point to the expression of degeneracy in hippocampal physiology and plasticity. We assess the potential of degeneracy as a framework to achieve the conjoint goals of encoding and homeostasis without cross-interferences. We postulate that biological complexity, involving interactions among the numerous parameters spanning different scales of analysis, could establish disparate routes towards accomplishing these conjoint goals. These disparate routes then provide several degrees of freedom to the encoding-homeostasis system in accomplishing its tasks in an input- and state-dependent manner. Finally, the expression of degeneracy spanning multiple scales offers an ideal reconciliation to several outstanding controversies, through the recognition that the seemingly contradictory disparate observations are merely alternate routes that the system might recruit towards accomplishment of its goals.
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Affiliation(s)
- Rahul K. Rathour
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
| | - Rishikesh Narayanan
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
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18
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Oprea TI, Bologa CG, Brunak S, Campbell A, Gan GN, Gaulton A, Gomez SM, Guha R, Hersey A, Holmes J, Jadhav A, Jensen LJ, Johnson GL, Karlson A, Leach AR, Ma’ayan A, Malovannaya A, Mani S, Mathias SL, McManus MT, Meehan TF, von Mering C, Muthas D, Nguyen DT, Overington JP, Papadatos G, Qin J, Reich C, Roth BL, Schürer SC, Simeonov A, Sklar LA, Southall N, Tomita S, Tudose I, Ursu O, Vidovic D, Waller A, Westergaard D, Yang JJ, Zahoránszky-Köhalmi G. Unexplored therapeutic opportunities in the human genome. Nat Rev Drug Discov 2018; 17:317-332. [PMID: 29472638 PMCID: PMC6339563 DOI: 10.1038/nrd.2018.14] [Citation(s) in RCA: 209] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A large proportion of biomedical research and the development of therapeutics is focused on a small fraction of the human genome. In a strategic effort to map the knowledge gaps around proteins encoded by the human genome and to promote the exploration of currently understudied, but potentially druggable, proteins, the US National Institutes of Health launched the Illuminating the Druggable Genome (IDG) initiative in 2014. In this article, we discuss how the systematic collection and processing of a wide array of genomic, proteomic, chemical and disease-related resource data by the IDG Knowledge Management Center have enabled the development of evidence-based criteria for tracking the target development level (TDL) of human proteins, which indicates a substantial knowledge deficit for approximately one out of three proteins in the human proteome. We then present spotlights on the TDL categories as well as key drug target classes, including G protein-coupled receptors, protein kinases and ion channels, which illustrate the nature of the unexplored opportunities for biomedical research and therapeutic development.
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Affiliation(s)
- Tudor I. Oprea
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
- UNM Comprehensive Cancer Center, Albuquerque, NM, USA
- Department of Rheumatology and Inflammation Research, Institute of Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Cristian G. Bologa
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Søren Brunak
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Anna Gaulton
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Shawn M. Gomez
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, USA
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Rajarshi Guha
- National Center for Advancing Translational Sciences (NCATS), National Institutes of Health (NIH), Rockville, MD, USA
| | - Anne Hersey
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Jayme Holmes
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Ajit Jadhav
- National Center for Advancing Translational Sciences (NCATS), National Institutes of Health (NIH), Rockville, MD, USA
| | - Lars Juhl Jensen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gary L. Johnson
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Anneli Karlson
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
- Present addresses: SciBite Limited, BioData Innovation Centre, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Andrew R. Leach
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Avi Ma’ayan
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | | | - Subramani Mani
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Stephen L. Mathias
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | | | - Terrence F. Meehan
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
| | | | - Daniel Muthas
- Respiratory, Inflammation and Autoimmunity Diseases, Innovative Medicines and Early Development Biotech Unit, AstraZeneca R&D Gothenburg, Mölndal, Sweden
| | - Dac-Trung Nguyen
- National Center for Advancing Translational Sciences (NCATS), National Institutes of Health (NIH), Rockville, MD, USA
| | - John P. Overington
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
- Medicines Discovery Catapult, Alderley Edge, UK
| | - George Papadatos
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
- GlaxoSmithKline, Stevenage, UK
| | - Jun Qin
- Baylor College of Medicine, Houston, TX, USA
| | | | - Bryan L. Roth
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Stephan C. Schürer
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Anton Simeonov
- National Center for Advancing Translational Sciences (NCATS), National Institutes of Health (NIH), Rockville, MD, USA
| | - Larry A. Sklar
- UNM Comprehensive Cancer Center, Albuquerque, NM, USA
- Center for Molecular Discovery, University of New Mexico Cancer Center, University of New Mexico, Albuquerque, NM, USA
- Department of Pathology, University of New Mexico, Albuquerque, NM, USA
| | - Noel Southall
- National Center for Advancing Translational Sciences (NCATS), National Institutes of Health (NIH), Rockville, MD, USA
| | - Susumu Tomita
- Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Ilinca Tudose
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL-EBI), Wellcome Genome Campus, Hinxton, Cambridge, UK
- Google Germany GmbH, München, Germany
| | - Oleg Ursu
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Dušica Vidovic
- Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Anna Waller
- Center for Molecular Discovery, University of New Mexico Cancer Center, University of New Mexico, Albuquerque, NM, USA
| | - David Westergaard
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jeremy J. Yang
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
| | - Gergely Zahoránszky-Köhalmi
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM, USA
- NIH-NCATS, Rockville, MD, USA
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19
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Jiménez-Vargas JM, Possani LD, Luna-Ramírez K. Arthropod toxins acting on neuronal potassium channels. Neuropharmacology 2017; 127:139-160. [PMID: 28941737 DOI: 10.1016/j.neuropharm.2017.09.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 09/13/2017] [Accepted: 09/15/2017] [Indexed: 01/01/2023]
Abstract
Arthropod venoms are a rich mixture of biologically active compounds exerting different physiological actions across diverse phyla and affecting multiple organ systems including the central nervous system. Venom compounds can inhibit or activate ion channels, receptors and transporters with high specificity and affinity providing essential insights into ion channel function. In this review, we focus on arthropod toxins (scorpions, spiders, bees and centipedes) acting on neuronal potassium channels. A brief description of the K+ channels classification and structure is included and a compendium of neuronal K+ channels and the arthropod toxins that modify them have been listed. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Juana María Jiménez-Vargas
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad, 2001, Colonia Chamilpa, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - Lourival D Possani
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad, 2001, Colonia Chamilpa, Apartado Postal 510-3, Cuernavaca 62210, Mexico
| | - Karen Luna-Ramírez
- Illawarra Health and Medical Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
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20
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Altered ionic currents and amelioration by IGF-1 and PACAP in motoneuron-derived cells modelling SBMA. Biophys Chem 2017; 229:68-76. [PMID: 28511915 DOI: 10.1016/j.bpc.2017.05.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 05/07/2017] [Indexed: 12/31/2022]
Abstract
Spinal and bulbar muscular atrophy (SBMA), also known as Kennedy's disease, is a motor neuron disease caused by the expansion of a polymorphic CAG tandem repeat encoding a polyglutamine (polyQ) tract in the androgen receptor (AR) gene. SBMA is triggered by the binding of mutant AR to its natural ligands, testosterone and dihydrotestosterone (DHT). To investigate the neuronal alterations of motor neuron cell models of SBMA, we applied patch-clamp methods to verify how polyQ expansions in the AR alter cell ionic currents. We used mouse motoneuron-derived MN-1 cells expressing normal AR (MN24Q) and mutant AR (MN100Q treated cells with vehicle EtOH and DHT). We observed a reduction of the current flux mainly at depolarizing potentials in the DHT-treated cells, while the dissection of macroscopic currents showed single different cationic currents belonging to voltage-gated channels. Also, we treated the cells with IGF-1 and PACAP, which have previously been shown to protect MN-1 cells from the toxicity of mutant AR, and we found an amelioration of the altered currents. Our results suggest that the electrophysiological correlate of SBMA is a suitable reference point for the identification of disease symptoms and for future therapeutic targets.
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21
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Thiffault I, Speca DJ, Austin DC, Cobb MM, Eum KS, Safina NP, Grote L, Farrow EG, Miller N, Soden S, Kingsmore SF, Trimmer JS, Saunders CJ, Sack JT. A novel epileptic encephalopathy mutation in KCNB1 disrupts Kv2.1 ion selectivity, expression, and localization. ACTA ACUST UNITED AC 2016; 146:399-410. [PMID: 26503721 PMCID: PMC4621747 DOI: 10.1085/jgp.201511444] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A missense mutation in the pore-forming α subunit of a delayed rectifier Kv channel is associated with epileptic encephalopathy, alters the cation selectivity of voltage-gated currents, and disrupts channel expression and localization. The epileptic encephalopathies are a group of highly heterogeneous genetic disorders. The majority of disease-causing mutations alter genes encoding voltage-gated ion channels, neurotransmitter receptors, or synaptic proteins. We have identified a novel de novo pathogenic K+ channel variant in an idiopathic epileptic encephalopathy family. Here, we report the effects of this mutation on channel function and heterologous expression in cell lines. We present a case report of infantile epileptic encephalopathy in a young girl, and trio-exome sequencing to determine the genetic etiology of her disorder. The patient was heterozygous for a de novo missense variant in the coding region of the KCNB1 gene, c.1133T>C. The variant encodes a V378A mutation in the α subunit of the Kv2.1 voltage-gated K+ channel, which is expressed at high levels in central neurons and is an important regulator of neuronal excitability. We found that expression of the V378A variant results in voltage-activated currents that are sensitive to the selective Kv2 channel blocker guangxitoxin-1E. These voltage-activated Kv2.1 V378A currents were nonselective among monovalent cations. Striking cell background–dependent differences in expression and subcellular localization of the V378A mutation were observed in heterologous cells. Further, coexpression of V378A subunits and wild-type Kv2.1 subunits reciprocally affects their respective trafficking characteristics. A recent study reported epileptic encephalopathy-linked missense variants that render Kv2.1 a tonically activated, nonselective cation channel that is not voltage activated. Our findings strengthen the correlation between mutations that result in loss of Kv2.1 ion selectivity and development of epileptic encephalopathy. However, the strong voltage sensitivity of currents from the V378A mutant indicates that the loss of voltage-sensitive gating seen in all other reported disease mutants is not required for an epileptic encephalopathy phenotype. In addition to electrophysiological differences, we suggest that defects in expression and subcellular localization of Kv2.1 V378A channels could contribute to the pathophysiology of this KCNB1 variant.
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Affiliation(s)
- Isabelle Thiffault
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108
| | - David J Speca
- Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
| | - Daniel C Austin
- Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
| | - Melanie M Cobb
- Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
| | - Kenneth S Eum
- Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
| | - Nicole P Safina
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108
| | - Lauren Grote
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108
| | - Emily G Farrow
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108
| | - Neil Miller
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108
| | - Sarah Soden
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108 Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108 University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108
| | - Stephen F Kingsmore
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108 Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108 Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108 University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108
| | - James S Trimmer
- Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616 Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
| | - Carol J Saunders
- Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108 Center for Pediatric Genomic Medicine, Department of Pathology and Laboratory Medicine, and Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO 64108 University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108
| | - Jon T Sack
- Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616 Department of Neurobiology, Physiology and Behavior, Department of Physiology and Membrane Biology, and Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, CA 95616
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Affiliation(s)
- I P Martins
- Department of Neurosciences, Instituto de Medicina Molecular, Lisbon Faculty of Medicine, Lisbon, Portugal.
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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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Sifi N, Martin-Eauclaire MF, Laraba-Djebari F. K(+) channel blocker-induced neuroinflammatory response and neurological disorders: immunomodulatory effects of astaxanthin. Inflamm Res 2016; 65:623-34. [PMID: 27052008 DOI: 10.1007/s00011-016-0945-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 03/18/2016] [Accepted: 03/30/2016] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVE Channelopathies due to the brain ion channel dysfunction is considered to be an important mechanism involved in various neurodegenerative diseases. In this study, we evaluated the ability of kaliotoxin (KTX) as K(+) channel blocker to induce neuro-inflammatory response and neurodegenerative alteration. We also investigate the effects of astaxanthin (ATX) against KTX disorders. MATERIAL AND TREATMENT NMRI mice were injected with KTX (1 pg/kg, by i.c.v route) with or without pretreatment using ATX (80 mg/kg, o.p route). RESULTS Results showed that KTX was detected in cerebral cortex area due to its binding to the specific receptors (immunofluorescence analysis). It induced an activation of inflammatory cascade characterized by an increase of IL-6, TNFα, NO, MDA levels and NF-κB expression associated to a decrease of GSH level. The neuroinflammatory response is accompanied with cerebral alterations and blood-brain barrier (BBB) disruption. The use of ATX prior to the KTX exerts a preventive effect not only on the neuroinflammation but also on altered tissues and the BBB disruption. CONCLUSIONS Kaliotoxin is able to induce neurological disorders by blocking the K(+) ion channel, and ATX suppresses this alterations with down regulation of IL-6, TNF-α and NF-κB expression in the brain.
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Affiliation(s)
- Nesrine Sifi
- USTHB, Faculty of Biological Sciences, Laboratory of Cellular and Molecular Biology, BP32, El Alia, Bab Ezzouar, 16111, Algiers, Algeria
| | | | - Fatima Laraba-Djebari
- USTHB, Faculty of Biological Sciences, Laboratory of Cellular and Molecular Biology, BP32, El Alia, Bab Ezzouar, 16111, Algiers, Algeria.
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25
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Ovsepian SV, LeBerre M, Steuber V, O'Leary VB, Leibold C, Oliver Dolly J. Distinctive role of KV1.1 subunit in the biology and functions of low threshold K+ channels with implications for neurological disease. Pharmacol Ther 2016; 159:93-101. [DOI: 10.1016/j.pharmthera.2016.01.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Li S, Kalappa BI, Tzounopoulos T. Noise-induced plasticity of KCNQ2/3 and HCN channels underlies vulnerability and resilience to tinnitus. eLife 2015; 4. [PMID: 26312501 PMCID: PMC4592936 DOI: 10.7554/elife.07242] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 08/22/2015] [Indexed: 12/11/2022] Open
Abstract
Vulnerability to noise-induced tinnitus is associated with increased spontaneous firing rate in dorsal cochlear nucleus principal neurons, fusiform cells. This hyperactivity is caused, at least in part, by decreased Kv7.2/3 (KCNQ2/3) potassium currents. However, the biophysical mechanisms underlying resilience to tinnitus, which is observed in noise-exposed mice that do not develop tinnitus (non-tinnitus mice), remain unknown. Our results show that noise exposure induces, on average, a reduction in KCNQ2/3 channel activity in fusiform cells in noise-exposed mice by 4 days after exposure. Tinnitus is developed in mice that do not compensate for this reduction within the next 3 days. Resilience to tinnitus is developed in mice that show a re-emergence of KCNQ2/3 channel activity and a reduction in HCN channel activity. Our results highlight KCNQ2/3 and HCN channels as potential targets for designing novel therapeutics that may promote resilience to tinnitus.
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Affiliation(s)
- Shuang Li
- Departments of Otolaryngology and Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Bopanna I Kalappa
- Departments of Otolaryngology and Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Thanos Tzounopoulos
- Departments of Otolaryngology and Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, United States
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28
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Forensische Molekularpathologie. Rechtsmedizin (Berl) 2014. [DOI: 10.1007/s00194-014-0975-0] [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]
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29
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Kipfer S, Strupp M. The Clinical Spectrum of Autosomal-Dominant Episodic Ataxias. Mov Disord Clin Pract 2014; 1:285-290. [PMID: 30713867 DOI: 10.1002/mdc3.12075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Revised: 06/16/2014] [Accepted: 06/20/2014] [Indexed: 11/06/2022] Open
Abstract
Autosomal-dominant episodic ataxias (EAs) represent a clinically and genetically heterogeneous group of disorders characterized by recurrent episodes of cerebellar ataxia (CA). Ataxia episodes are usually of short duration and often triggered by specific stimuli. There are currently seven classified subtypes of EA. EA types 1 and 2 have the highest prevalence and are therefore the clinically most relevant. Between attacks, EA 1 is associated with myokymia. In EA 2, often an interictal downbeat nystagmus with other cerebellar ocular dysfunctions is present; patients with EA 2 may display slowly progessive ataxia and vermian atrophy. EA 1 and 2 are both channelopathies, affecting the potassium channel gene, KCNA1, in EA 1 and the PQ calcium channel-encoding gene, CACNA1A, in EA 2. The types EA 3 to 7 are very rare and have to be further elucidated. Here, we review the historical, clinical, and genetic aspects of autosomal-dominant EAs and their current treatment, focusing on EA 1 and 2.
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Affiliation(s)
- Stefan Kipfer
- Department of Neurology Kantonsspital Olten Switzerland
| | - Michael Strupp
- Department of Neurology and German Center for Vertigo and Balance Disorders University Hospital Munich Munich Germany
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Yadollahpour A, Firouzabadi SM, Shahpari M, Mirnajafi-Zadeh J. Repetitive transcranial magnetic stimulation decreases the kindling induced synaptic potentiation: Effects of frequency and coil shape. Epilepsy Res 2014; 108:190-201. [DOI: 10.1016/j.eplepsyres.2013.11.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 10/27/2013] [Accepted: 11/26/2013] [Indexed: 10/25/2022]
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Chang WP, Shyu BC. Anterior Cingulate epilepsy: mechanisms and modulation. Front Integr Neurosci 2014; 7:104. [PMID: 24427123 PMCID: PMC3879463 DOI: 10.3389/fnint.2013.00104] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 12/16/2013] [Indexed: 11/13/2022] Open
Abstract
Epilepsy is a common neurological disorder, about 1% population worldwide suffered from this disease. In 1989, the International League Against Epilepsy (ILAE) classified anterior cingulate epilepsy as a form of frontal lobe epilepsy (FLE). FLE is the second most common type of epilepsy. Previous clinical studies showed that FLE account an important cause in refractory epilepsy, therefore to find alternative approach to modulate FLE is very important. Basic research using animal models and brain slice have revealed some insights on the epileptogenesis and modulation of seizure in anterior cingulate cortex (ACC). Interneurons play an important role in the synchronization of cingulate epilepsy. Research has shown that the epileptogenesis of seizure originated from mesial frontal lobe might be caused by a selective increase in nicotine-evoked γ-aminobutyric acid (GABA) inhibition, because the application of the GABAA receptor antagonist picrotoxin inhibited epileptic discharges. Gap junctions are also involved in the regulation of cingulate epilepsy. Previous studies have shown that the application of gap junction blockers could attenuate ACC seizures, while gap junction opener could enhance them in an in vitro preparation. μ-Opioid receptors have been shown to be involved in the epileptic synchronization mechanism in ACC seizures in a brain slice preparation. Application of the μ-opioid agonist DAMGO significantly abolished the ictal discharges in a 4-aminopyridine induced electrographic seizure model in ACC. Basic research has also found that thalamic modulation has an inhibitory effect on ACC seizures. Studies have shown that the medial thalamus may be a target for deep brain stimulation to cure ACC seizures.
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Affiliation(s)
- Wei-Pang Chang
- Graduate Institute of Life Science, National Defense Medical Center Taipei, Taiwan ; Institute of Biomedical Science, Academia Sinica Taipei, Taiwan
| | - Bai-Chuang Shyu
- Graduate Institute of Life Science, National Defense Medical Center Taipei, Taiwan ; Institute of Biomedical Science, Academia Sinica Taipei, Taiwan
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32
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Gao G, Dudley SC. SCN5A splicing variants and the possibility of predicting heart failure-associated arrhythmia. Expert Rev Cardiovasc Ther 2013; 11:117-9. [PMID: 23405830 DOI: 10.1586/erc.12.180] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Abstract
Aminopyridines are members of a family of monoamino and diamino derivatives of pyridine, and their principal mechanism of action is dose-dependent blockade of voltage-gated potassium channels, in particular, fast voltage-gated potassium channels. To date, only 2 main broad-spectrum potassium channel blockers, 4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP), have been used as investigational new drugs in various neurological diseases. More recently, licensed versions of these compounds including dalfampridine extended release (Fampyra, Biogen Idec) for the improvement of walking in adult patients with multiple sclerosis, and amifampridine (Firdapse, Biomarin Europe Ltd) for the treatment of Lambert-Eaton myasthenic syndrome have been released, and the costs associated with using these new products highlights the importance of evaluating the clinically meaningful treatment effects of these drugs.The current review summarizes the evidence of aminopyridine use in neurological conditions and in particular presents a systematic review of all randomized trials of 3,4-DAP in Lambert-Eaton myasthenic syndrome to determine the efficacy of this treatment using meta-analysis of clinical and electrophysiological end points.
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Abstract
Potassium (K(+)) channels are essential to neuronal signaling and survival. Here we show that these proteins are targets of reactive oxygen species in mammalian brain and that their oxidation contributes to neuropathy. Thus, the KCNB1 (Kv2.1) channel, which is abundantly expressed in cortex and hippocampus, formed oligomers upon exposure to oxidizing agents. These oligomers were ∼10-fold more abundant in the brain of old than young mice. Oxidant-induced oligomerization of wild-type KCNB1 enhanced apoptosis in neuronal cells subject to oxidative insults. Consequently, a KCNB1 variant resistant to oxidation, obtained by mutating a conserved cysteine to alanine, (C73A), was neuroprotective. The fact that oxidation of KCNB1 is toxic, argues that this mechanism may contribute to neuropathy in conditions characterized by high levels of oxidative stress, such as Alzheimer's disease (AD). Accordingly, oxidation of KCNB1 channels was exacerbated in the brain of a triple transgenic mouse model of AD (3xTg-AD). The C73A variant protected neuronal cells from apoptosis induced by incubation with β-amyloid peptide (Aβ(1-42)). In an invertebrate model (Caenorhabditis elegans) that mimics aspects of AD, a C73A-KCNB1 homolog (C113S-KVS-1) protected specific neurons from apoptotic death induced by ectopic expression of human Aβ(1-42). Together, these data underscore a novel mechanism of toxicity in neurodegenerative disease.
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Zhu J, Alsaber R, Zhao J, Ribeiro-Hurley E, Thornhill WB. Characterization of the Kv1.1 I262T and S342I mutations associated with episodic ataxia 1 with distinct phenotypes. Arch Biochem Biophys 2012; 524:99-105. [PMID: 22609616 DOI: 10.1016/j.abb.2012.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 10/28/2022]
Abstract
Episodic ataxia type 1 (EA-1) is an autosomal dominant neurological disorder caused by mutations in the potassium channel Kv1.1. Two EA-1 mutations, I262T and S342I, have been identified with unique clinical phenotypes, but their functional and biochemical properties have not been fully investigated. Here we characterized these two mutations in transfected mammalian cells both electrophysiologically and biochemically. We found that the I262T mutation resulted in a ∼7-fold reduction in the K+ current amplitude compared with wild type channels, whereas the S342I mutation produced an apparent nonfunctional channel when expressed alone. Co-expression of wild type and mutant channels showed that both I262T and S342I exerted dominant-negative effects on wild type function. The protein expression analysis showed that I262T resulted in ∼2-fold decrease in surface protein levels of Kv1.1, which partially contributed to the decreased surface conductance density, whereas the S342I mutation showed no effects on surface protein expression. Conservative amino acid substitution experiments suggest that the wild type amino acids at these two positions are required for normal channel function. Our results broaden the knowledge of EA-1 mutations and the underlying mechanisms of the associated disorder.
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Affiliation(s)
- Jing Zhu
- Department of Biological Sciences and Center for Cancer, Genetic Diseases, and Gene Regulation, Fordham University, Bronx, NY 10458, USA
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36
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Zaharenko AJ, Schiavon E, Ferreira WA, Lecchi M, de Freitas JC, Richardson M, Wanke E. Characterization of selectivity and pharmacophores of type 1 sea anemone toxins by screening seven Na(v) sodium channel isoforms. Peptides 2012; 34:158-67. [PMID: 21802465 DOI: 10.1016/j.peptides.2011.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 07/07/2011] [Accepted: 07/07/2011] [Indexed: 12/01/2022]
Abstract
During their evolution, animals have developed a set of cysteine-rich peptides capable of binding various extracellular sites of voltage-gated sodium channels (VGSC). Sea anemone toxins that target VGSCs delay their inactivation process, but little is known about their selectivities. Here we report the investigation of three native type 1 toxins (CGTX-II, δ-AITX-Bcg1a and δ-AITX-Bcg1b) purified from the venom of Bunodosoma cangicum. Both δ-AITX-Bcg1a and δ-AITX-Bcg1b toxins were fully sequenced. The three peptides were evaluated by patch-clamp technique among Nav1.1-1.7 isoforms expressed in mammalian cell lines, and their preferential targets are Na(v)1.5>1.6>1.1. We also evaluated the role of some supposedly critical residues in the toxins which would interact with the channels, and observed that some substitutions are not critical as expected. In addition, CGTX-II and δ-AITX-Bcg1a evoke different shifts in activation/inactivation Boltzmann curves in Nav1.1 and 1.6. Moreover, our results suggest that the interaction region between toxins and VGSCs is not restricted to the supposed site 3 (S3-S4 linker of domain IV), and this may be a consequence of distinct surface of contact of each peptide vs. targeted channel. Our data suggest that the contact surfaces of each peptide may be related to their surface charges, as CGTX-II is more positive than δ-AITX-Bcg1a and δ-AITX-Bcg1b.
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37
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Schiavon E, Pedraza-Escalona M, Gurrola GB, Olamendi-Portugal T, Corzo G, Wanke E, Possani LD. Negative-shift activation, current reduction and resurgent currents induced by β-toxins from Centruroides scorpions in sodium channels. Toxicon 2011; 59:283-93. [PMID: 22200496 DOI: 10.1016/j.toxicon.2011.12.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/03/2011] [Accepted: 12/06/2011] [Indexed: 12/19/2022]
Abstract
The β-toxins purified from the New World scorpion venoms of the Centruroides species affect several voltage-gated sodium channels (VGSCs) and thus are essential tools not only for the discrimination of different channel sub-types but also for studying the structure-function relationship between channels and toxins. This communication reports the results obtained with four different peptides purified from three species of Centruroides scorpions and assayed on seven distinct isoforms of VGSC (Na(v)1.1-Na(v)1.7) by specific functional analysis conducted through single cell electrophysiology. The toxins studied were CssII from Centruroides suffusus suffusus, Cll1 and Cll2 from Centruroides limpidus limpidus and a novel toxin from Centruroides noxius, which was characterized for the first time here. It has 67 amino acid residues and four disulfide bridges with a molecular mass of 7626 Da. Three different functional features were identified: current reduction of macroscopic conductance, left shift of the voltage-dependent activation and induction of resurgent currents at negative voltages following brief, strong depolarizations. The isoforms which revealed to be more affected resulted to be Na(v)1.6 > 1.1 > 1.2 and, for the first time, a β-toxin is here shown to induce resurgent current also in isoforms different from Na(v)1.6. Additionally, these results were analyzed with molecular modelling. In conclusion, although the four toxins have a high degree of identity, they display tri-modal function, each of which shows selectivity among the different sub-types of Na+ -channels. Thus, they are invaluable as tools for structure-function studies of β-toxins and offer a basis for the design of novel ion channel-specific drugs.
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Affiliation(s)
- Emanuele Schiavon
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy.
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Devaraneni PK, Devereaux JJ, Valiyaveetil FI. In vitro folding of KvAP, a voltage-gated K+ channel. Biochemistry 2011; 50:10442-50. [PMID: 22044112 DOI: 10.1021/bi2012965] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this contribution, we report in vitro folding of the archaebacterial voltage-gated K(+) channel, K(v)AP. We show that in vitro folding of the K(v)AP channel from the extensively unfolded state requires lipid vesicles and that the refolded channel is biochemically and functionally similar to the native channel. The in vitro folding process is slow at room temperature, and the folding yield depends on the composition of the lipid bilayer. The major factor influencing refolding is temperature, and almost quantitative refolding of the K(v)AP channel is observed at 80 °C. To differentiate between insertion into the bilayer and folding within the bilayer, we developed a cysteine protection assay. Using this assay, we demonstrate that insertion of the unfolded protein into the bilayer is relatively fast at room temperature and independent of lipid composition, suggesting that temperature and bilayer composition influence folding within the bilayer. Further, we demonstrate that in vitro folding provides an effective method for obtaining high yields of the native channel. Our studies suggest that the K(v)AP channel provides a good model system for investigating the folding of a multidomain integral membrane protein.
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Affiliation(s)
- Prasanna K Devaraneni
- The Program in Chemical Biology, Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon 97239, United States
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Strupp M, Brandt T. Current treatment of vestibular, ocular motor disorders and nystagmus. Ther Adv Neurol Disord 2011; 2:223-39. [PMID: 21179531 DOI: 10.1177/1756285609103120] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Vertigo and dizziness are among the most common complaints with a lifetime prevalence of about 30%. The various forms of vestibular disorders can be treated with pharmacological therapy, physical therapy, psychotherapeutic measures or, rarely, surgery. In this review, the current pharmacological treatment options for peripheral and central vestibular, cerebellar and ocular motor disorders will be described. They are as follows for peripheral vestibular disorders. In vestibular neuritis recovery of the peripheral vestibular function can be improved by treatment with oral corticosteroids. In Menière's disease a recent study showed long-term high-dose treatment with betahistine has a significant effect on the frequency of the attacks. The use of aminopyridines introduced a new therapeutic principle in the treatment of downbeat and upbeat nystagmus and episodic ataxia type 2 (EA 2). These potassium channel blockers presumably increase the activity and excitability of cerebellar Purkinje cells, thereby augmenting the inhibitory influence of these cells on vestibular and cerebellar nuclei. A few studies showed that baclofen improves periodic alternating nystagmus, and gabapentin and memantine, pendular nystagmus. However, many other eye movement disorders such as ocular flutter opsoclonus, central positioning, or see-saw nystagmus are still difficult to treat. Although progress has been made in the treatment of vestibular neuritis, downbeat and upbeat nystagmus, as well as EA 2, state-of-the-art trials must still be performed on many vestibular and ocular motor disorders, namely Menière's disease, bilateral vestibular failure, vestibular paroxysmia, vestibular migraine, and many forms of central eye movement disorders.
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Affiliation(s)
- Michael Strupp
- Professor of Neurology and Clinical Neurophysiology, University of Munich, Klinikum Grosshadern, Munich, Germany
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Fortin DL, Dunn TW, Fedorchak A, Allen D, Montpetit R, Banghart MR, Trauner D, Adelman JP, Kramer RH. Optogenetic photochemical control of designer K+ channels in mammalian neurons. J Neurophysiol 2011; 106:488-96. [PMID: 21525363 PMCID: PMC3129715 DOI: 10.1152/jn.00251.2011] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 04/25/2011] [Indexed: 11/22/2022] Open
Abstract
Currently available optogenetic tools, including microbial light-activated ion channels and transporters, are transforming systems neuroscience by enabling precise remote control of neuronal firing, but they tell us little about the role of indigenous ion channels in controlling neuronal function. Here, we employ a chemical-genetic strategy to engineer light sensitivity into several mammalian K(+) channels that have different gating and modulation properties. These channels provide the means for photoregulating diverse electrophysiological functions. Photosensitivity is conferred on a channel by a tethered ligand photoswitch that contains a cysteine-reactive maleimide (M), a photoisomerizable azobenzene (A), and a quaternary ammonium (Q), a K(+) channel pore blocker. Using mutagenesis, we identify the optimal extracellular cysteine attachment site where MAQ conjugation results in pore blockade when the azobenzene moiety is in the trans but not cis configuration. With this strategy, we have conferred photosensitivity on channels containing Kv1.3 subunits (which control axonal action potential repolarization), Kv3.1 subunits (which contribute to rapid-firing properties of brain neurons), Kv7.2 subunits (which underlie "M-current"), and SK2 subunits (which are Ca(2+)-activated K(+) channels that contribute to synaptic responses). These light-regulated channels may be overexpressed in genetically targeted neurons or substituted for native channels with gene knockin technology to enable precise optopharmacological manipulation of channel function.
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Affiliation(s)
- Doris L Fortin
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3200, USA
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Stergiou C, Zisimopoulou P, Tzartos SJ. Expression of water-soluble, ligand-binding concatameric extracellular domains of the human neuronal nicotinic receptor alpha4 and beta2 subunits in the yeast Pichia pastoris: glycosylation is not required for ligand binding. J Biol Chem 2011; 286:8884-92. [PMID: 21252231 DOI: 10.1074/jbc.m110.171645] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated cation channels that are responsible for cell communication via the neurotransmitter acetylcholine. The predominant nAChR subtype in the mammalian brain with a high affinity for nicotine is composed of α4 and β2 subunits. This nAChR subtype is responsible for addiction to nicotine and is thought to be implicated in Alzheimer and Parkinson diseases and therefore presents an important target for drug design. In an effort to obtain water-soluble, ligand-binding domains of the human α4β2 nAChR for structural studies, we expressed the extracellular domains (ECDs) of these subunits in the eukaryotic expression system Pichia pastoris. The wild-type ECDs and their mutants containing the more hydrophilic Cys-loop from the snail acetylcholine-binding protein (individually expressed or coexpressed) did not demonstrate any specific interaction with ligands. We then linked the mutated ECDs with the 24-amino acid peptide (AGS)(8) and observed that the β2-24-α4 ECD concatamer, but not the α4-24-β2 one, exhibited very satisfactory water solubility and ligand binding properties. The (125)I-epibatidine and [(3)H]nicotine bound to β2-24-α4 with dissociation constants (K(d)) of 0.38 and 19 nm, respectively, close to the published values for the intact α4β2 AChR. In addition, (125)I-epibatidine binding was blocked by nicotine, cytisine, acetylcholine, and carbamylcholine with inhibition constants (K(i)) of 20.64, 3.24, 242, and 2,254 nm, respectively. Interestingly, deglycosylation of the concatamer did not affect its ligand binding properties. Furthermore, the deglycosylated β2-24-α4 ECD existed mainly in monomeric form, thus forming an appropriate material for structural studies and possibly for pharmacological evaluation of novel α4β2 nAChR-specific agonists.
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Affiliation(s)
- Christos Stergiou
- Department of Biochemistry, Hellenic Pasteur Institute, GR11521 Athens, Greece
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Abstract
Sixty years ago the clinical neurophysiology of epilepsy had progressed to the stage that it posed questions that could be addressed by major advances in cellular electrophysiology made around the that time. However, it took about 25-30 years to build up serious momentum in understanding the mechanisms of epileptic discharges. Over the past 2-3 decades developments in pharmacology and molecular biology have substantially increased the depth and complexity of our insights into the nervous system in general and the epileptic brain in particular. One of the biggest advances in our understanding of the brain is in its plasticity in the adult - that is its ability to modify its structure and function. The current state of play is that for most chronic epileptic foci it is possible to identify multiple differences from normal brain tissue in both the structure and function of neurons, neuronal networks and glia. This review will chart some of this progress to give an idea of the pace of advances over the decades.
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Affiliation(s)
- John G R Jefferys
- Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK.
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43
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Pacheco Otalora LF, Skinner F, Oliveira MS, Farrell B, Arshadmansab MF, Pandari T, Garcia I, Robles L, Rosas G, Mello CF, Ermolinsky BS, Garrido-Sanabria ER. Chronic deficit in the expression of voltage-gated potassium channel Kv3.4 subunit in the hippocampus of pilocarpine-treated epileptic rats. Brain Res 2010; 1368:308-16. [PMID: 20971086 DOI: 10.1016/j.brainres.2010.10.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2010] [Revised: 10/11/2010] [Accepted: 10/14/2010] [Indexed: 10/18/2022]
Abstract
Voltage gated K(+) channels (Kv) are a highly diverse group of channels critical in determining neuronal excitability. Deficits of Kv channel subunit expression and function have been implicated in the pathogenesis of epilepsy. In this study, we investigate whether the expression of the specific subunit Kv3.4 is affected during epileptogenesis following pilocarpine-induced status epilepticus. For this purpose, we used immunohistochemistry, Western blotting assays and comparative analysis of gene expression using TaqMan-based probes and delta-delta cycle threshold (ΔΔCT) method of quantitative real-time polymerase chain reaction (qPCR) technique in samples obtained from age-matched control and epileptic rats. A marked down-regulation of Kv3.4 immunoreactivity was detected in the stratum lucidum and hilus of dentate gyrus in areas corresponding to the mossy fiber system of chronically epileptic rats. Correspondingly, a 20% reduction of Kv3.4 protein levels was detected in the hippocampus of chronic epileptic rats. Real-time quantitative PCR analysis of gene expression revealed that a significant 33% reduction of transcripts for Kv3.4 (gene Kcnc4) occurred after 1 month of pilocarpine-induced status epilepticus and persisted during the chronic phase of the model. These data indicate a reduced expression of Kv3.4 channels at protein and transcript levels in the epileptic hippocampus. Down-regulation of Kv3.4 in mossy fibers may contribute to enhanced presynaptic excitability leading to recurrent seizures in the pilocarpine model of temporal lobe epilepsy.
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Affiliation(s)
- Luis F Pacheco Otalora
- Department of Biological Sciences at the University of Texas at Brownsville and Center for Biomedical Studies, 80 Fort Brown, Brownsville, TX 78520, USA
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44
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Trivedi S, Liu J, Liu R, Bostwick R. Advances in functional assays for high-throughput screening of ion channels targets. Expert Opin Drug Discov 2010; 5:995-1006. [DOI: 10.1517/17460441.2010.513377] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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45
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Grimaldi D, Batista S, Poisson A, Verschelde HL, Vázquez-Sánchez F. The Almirall European Headache Awards 2009. J Headache Pain 2010; 11:207-14. [PMID: 20369271 PMCID: PMC3451906 DOI: 10.1007/s10194-010-0209-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 03/16/2010] [Indexed: 01/21/2023] Open
Abstract
The Almirall European Headache Awards (AEHA) were organized in conjunction with the European Headache Federation. The awards were held in 2009, aiming to share clinical experience and best practice in headache-related disease management. 56 unusual and challenging cases of headache from 5 European countries (Belgium, France, Italy, Portugal and Spain) were judged by a Scientific Committee including expert representatives from participating countries, acting as reviewers. Three cases were selected from each country. The 15 resulting cases were presented to the Scientific Committee in Madrid, Spain in November 2009 and awards were given to the top 5 presentations. This article presents details of these cases, including the award winning entries. They have been categorized into four main groups: (a) headaches in rare syndromes; (b) secondary headaches to infectious/autoimmune causes or post-trauma/mass occupation; (c) headache in unresolved cases; and (d) other relevant cases. First prize was awarded to a case involving a 55-year-old male with familial thrombocytopenia and a unilateral neuralgiform headache secondary to trigeminal vascular contact, and which was successfully treated with carbamazepine. Conclusions from the meeting include: rare syndromes do occur and require appropriate treatment to improve outcomes; concomitant diseases may impair adequate diagnosis and should be investigated; physicians should be cautious and treat possible serious underlying disease, whilst accurately clarifying the correct diagnosis; neurological examination and complementary tests may be required; consideration should be given to possible rare medication events; and some cases may remain without a clear cause or diagnosis and symptoms should be treated whilst investigations continue.
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Affiliation(s)
- Daniela Grimaldi
- Neurological Sciences Department, University of Bologna, Via U Foscolo 7, 40123 Bologna, Italy.
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46
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Wang X, Sun W, Zhu X, Li L, Du T, Mao W, Wu X, Wei H, Zhu S, Sun Y, Liu Y, Niu N, Wang Y, Liu Y. Paroxysmal kinesigenic choreoathetosis: evidence of linkage to the pericentromeric region of chromosome 16 in four Chinese families. Eur J Neurol 2010; 17:800-7. [PMID: 20158512 DOI: 10.1111/j.1468-1331.2009.02929.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Paroxysmal kinesigenic choreoathetosis (PKC) is an autosomal dominant condition characterized by abnormal involuntary movements precipitated by sudden movement. The pericentromeric region of chromosome 16 has been linked to PKC by several reports. This study was to localize and identify PKC gene in four Chinese PKC families. METHODS Genetic linkage mapping with eight markers spanning chromosome 16p12-q13 was performed in 43 family members. Genome-wide single nucleotide polymorphism (SNP) scans were performed on four individuals in Family 1 in which infantile convulsion (IC) was co-inherited with PKC. RESULTS Individuals in Family 1 presented with both IC and paroxysmal choreoathetosis (ICCA), and Families 2, 3, and 4 presented only with PKC. Evidence for linkage was found with a maximum two-point LOD score of 4.89 for D16S690 (theta = 0.0) and a maximum multipoint LOD score was 5.34 between D16S3080 and D16S3136. Haplotype analysis showed the disease locus was between D16S3093 and D16S3057. A total of 84 SNPs spanned on 16q12.1-q13 was not segregated with the PKC phenotype, which defined an unlinked region from rs9933187 to rs8044753. Thus, the critical region of the PKC gene is across the pericentromeric region of chromosome 16, and most likely maps to a region of 20.5 Mb (6.2 cM) between D16S3093 and rs9933187 (16p11.2-q12.1). CONCLUSION The assignment of the locus for PKC to the pericentromeric region of chromosome 16 is confirmed and putatively narrowed in the present study.
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Affiliation(s)
- X Wang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing, China
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Schiavon E, Stevens M, Zaharenko AJ, Konno K, Tytgat J, Wanke E. Voltage-gated sodium channel isoform-specific effects of pompilidotoxins. FEBS J 2010; 277:918-30. [PMID: 20059541 DOI: 10.1111/j.1742-4658.2009.07533.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pompilidotoxins (PMTXs, alpha and beta) are small peptides consisting of 13 amino acids purified from the venom of the solitary wasps Anoplius samariensis (alpha-PMTX) and Batozonellus maculifrons (beta-PMTX). They are known to facilitate synaptic transmission in the lobster neuromuscular junction, and to slow sodium channel inactivation. By using beta-PMTX, alpha-PMTX and four synthetic analogs with amino acid changes, we conducted a thorough study of the effects of PMTXs on sodium current inactivation in seven mammalian voltage-gated sodium channel (VGSC) isoforms and one insect VGSC (DmNa(v)1). By evaluating three components of which the inactivating current is composed (fast, slow and steady-state components), we could distinguish three distinct groups of PMTX effects. The first group concerned the insect and Na(v)1.6 channels, which showed a large increase in the steady-state current component without any increase in the slow component. Moreover, the dose-dependent increase in this steady-state component was correlated with the dose-dependent decrease in the fast component. A second group of effects concerned the Na(v)1.1, Na(v)1.2, Na(v)1.3 and Na(v)1.7 isoforms, which responded with a large increase in the slow component, and showed only a small steady-state component. As with the first group of effects, the slow component was dose-dependent and correlated with the decrease in the fast component. Finally, a third group of effects concerned Na(v)1.4 and Na(v)1.5, which did not show any change in the slow or steady-state component. These data shed light on the complex and intriguing behavior of VGSCs in response to PMTXs, helping us to better understand the molecular determinants explaining isoform-specific effects.
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Affiliation(s)
- Emanuele Schiavon
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
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48
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Redaelli E, Cassulini RR, Silva DF, Clement H, Schiavon E, Zamudio FZ, Odell G, Arcangeli A, Clare JJ, Alagón A, de la Vega RCR, Possani LD, Wanke E. Target promiscuity and heterogeneous effects of tarantula venom peptides affecting Na+ and K+ ion channels. J Biol Chem 2009; 285:4130-4142. [PMID: 19955179 DOI: 10.1074/jbc.m109.054718] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Venom-derived peptide modulators of ion channel gating are regarded as essential tools for understanding the molecular motions that occur during the opening and closing of ion channels. In this study, we present the characterization of five spider toxins on 12 human voltage-gated ion channels, following observations about the target promiscuity of some spider toxins and the ongoing revision of their "canonical" gating-modifying mode of action. The peptides were purified de novo from the venom of Grammostola rosea tarantulas, and their sequences were confirmed by Edman degradation and mass spectrometry analysis. Their effects on seven tetrodotoxin-sensitive Na(+) channels, the three human ether-à-go-go (hERG)-related K(+) channels, and two human Shaker-related K(+) channels were extensively characterized by electrophysiological techniques. All the peptides inhibited ion conduction through all the Na(+) channels tested, although with distinctive patterns. The peptides also affected the three pharmaceutically relevant hERG isoforms differently. At higher concentrations, all peptides also modified the gating of the Na(+) channels by shifting the activation to more positive potentials, whereas more complex effects were recorded on hERG channels. No effects were evident on the two Shaker-related K(+) channels at concentrations well above the IC(50) value for the affected channels. Given the sequence diversity of the tested peptides, we propose that tarantula toxins should be considered both as multimode and target-promiscuous ion channel modulators; both features should not be ignored when extracting mechanistic interpretations about ion channel gating. Our observations could also aid in future structure-function studies and might help the development of novel ion channel-specific drugs.
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Affiliation(s)
- Elisa Redaelli
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy
| | - Rita Restano Cassulini
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy; the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Deyanira Fuentes Silva
- the Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, Coyoacán DF 04510, México
| | - Herlinda Clement
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Emanuele Schiavon
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy
| | - Fernando Z Zamudio
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - George Odell
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Annarosa Arcangeli
- the Dipartimento di Patologia e Oncologia Sperimentali, Università di Firenze, Viale Morgagni 50, 50134 Firenze, Italy
| | - Jeffrey J Clare
- Gene Expression and Protein Biochemistry, GlaxoSmithKline, Medicines Research Centre, Gunnels Wood Road, Stevenage, Herts SG1 2NY, United Kingdom, and
| | - Alejandro Alagón
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Ricardo C Rodríguez de la Vega
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México; the Structural and Computational Biology/Genome Biology Units, European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg 69117, Germany
| | - Lourival D Possani
- the Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Enzo Wanke
- From the Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milan, Italy.
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Abstract
BACKGROUND The lifelong prevalence of rotatory vertigo is 30%. Despite this high figure, patients with vertigo generally receive either inappropriate or inadequate treatment. However, the majority of vestibular disorders have a benign cause, take a favorable natural course, and respond positively to therapy. OBJECTIVE This review puts special emphasis on the medical rather than the physical, operative, or psychotherapeutic treatments available. METHODS A selected review of recent reports and studies on the medical treatment of peripheral and central vestibular disorders. RESULTS/CONCLUSIONS In vestibular neuritis, recovery of the peripheral vestibular function can be improved by oral corticosteroids; in Menière's disease, there is first evidence that high-dose, long-term administration of betahistine reduces attack frequency; carbamazepine or oxcarbamazepine is the treatment of first choice in vestibular paroxysmia, a disorder mainly caused by neurovascular cross-compression; the potassium channel blocker aminopyridine provides a new therapeutic principle for treatment of downbeat nystagmus, upbeat nystagmus, and episodic ataxia type 2.
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Affiliation(s)
- Thomas Brandt
- Ludwig-Maximilians-University, Institute of Clinical Neuroscience, Marchioninistr. 15, 81377 Munich, Germany.
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50
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Rivera-Arconada I, Roza C, Lopez-Garcia JA. Enhancing m currents: a way out for neuropathic pain? Front Mol Neurosci 2009; 2:10. [PMID: 19680469 PMCID: PMC2726036 DOI: 10.3389/neuro.02.010.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 07/23/2009] [Indexed: 12/19/2022] Open
Abstract
Almost three decades ago, the M current was identified and characterized in frog sympathetic neurons (Brown and Adams, 1980). The years following this discovery have seen a huge progress in the understanding of the function and the pharmacology of this current as well as on the structure of the underlying ion channels. Therapies for a number of syndromes involving abnormal levels of excitability in neurons are benefiting from research on M currents. At present, the potential of M current openers as analgesics for neuropathic pain is under discussion. Here we offer a critical view of existing data on the involvement of M currents in pain processing. We believe that enhancement of M currents at the site of injury may become a powerful strategy to alleviate pain in some peripheral neuropathies.
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Affiliation(s)
- Ivan Rivera-Arconada
- Departamento de Fisiología, Edificio de Medicina, Universidad de Alcala Madrid, Spain
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