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Teruel-Peña B, Gómez-Urquiza JL, Suleiman-Martos N, Prieto I, García-Cózar FJ, Ramírez-Sánchez M, Fernández-Martos C, Domínguez-Vías G. Systematic Review and Meta-Analyses of Aminopeptidases as Prognostic Biomarkers in Amyotrophic Lateral Sclerosis. Int J Mol Sci 2023; 24:ijms24087169. [PMID: 37108335 PMCID: PMC10138961 DOI: 10.3390/ijms24087169] [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: 03/01/2023] [Revised: 04/05/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons in the spinal cord, brain stem, and cerebral cortex. Biomarkers for ALS are essential for disease detection and to provide information on potential therapeutic targets. Aminopeptidases catalyze the cleavage of amino acids from the amino terminus of protein or substrates such as neuropeptides. Since certain aminopeptidases are known to increase the risk of neurodegeneration, such mechanisms may reveal new targets to determine their association with ALS risk and their interest as a diagnostic biomarker. The authors performed a systematic review and meta-analyses of genome-wide association studies (GWASs) to identify reported aminopeptidases genetic loci associated with the risk of ALS. PubMed, Scopus, CINAHL, ISI Web of Science, ProQuest, LILACS, and Cochrane databases were searched to retrieve eligible studies in English or Spanish, published up to 27 January 2023. A total of 16 studies were included in this systematic review, where a series of aminopeptidases could be related to ALS and could be promising biomarkers (DPP1, DPP2, DPP4, LeuAP, pGluAP, and PSA/NPEPPS). The literature reported the association of single-nucleotide polymorphisms (SNPs: rs10260404 and rs17174381) with the risk of ALS. The genetic variation rs10260404 in the DPP6 gene was identified to be highly associated with ALS susceptibility, but meta-analyses of genotypes in five studies in a matched cohort of different ancestry (1873 cases and 1861 control subjects) showed no ALS risk association. Meta-analyses of eight studies for minor allele frequency (MAF) also found no ALS association for the "C" allele. The systematic review identified aminopeptidases as possible biomarkers. However, the meta-analyses for rs1060404 of DPP6 do not show a risk associated with ALS.
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Affiliation(s)
- Bárbara Teruel-Peña
- Department of Health Sciences, University of Jaén, 23071 Jaén, Spain
- Department of Physiology, Faculty of Health Sciences, Ceuta University of Granada, 51001 Ceuta, Spain
| | - José Luís Gómez-Urquiza
- Nursing Department, Faculty of Health Sciences, Ceuta University of Granada, 51001 Ceuta, Spain
| | - Nora Suleiman-Martos
- Nursing Department, Faculty of Health Sciences, University of Granada, 18071 Granada, Spain
| | - Isabel Prieto
- Department of Health Sciences, University of Jaén, 23071 Jaén, Spain
| | | | | | | | - Germán Domínguez-Vías
- Department of Physiology, Faculty of Health Sciences, Ceuta University of Granada, 51001 Ceuta, Spain
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2
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Murphy JG, Gutzmann JJ, Lin L, Hu J, Petralia RS, Wang YX, Hoffman DA. R-type voltage-gated Ca 2+ channels mediate A-type K + current regulation of synaptic input in hippocampal dendrites. Cell Rep 2022; 38:110264. [PMID: 35045307 PMCID: PMC10496648 DOI: 10.1016/j.celrep.2021.110264] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 12/02/2021] [Accepted: 12/22/2021] [Indexed: 01/22/2023] Open
Abstract
The subthreshold voltage-gated transient K+ current (IA) carried by pore-forming Kv4.2 subunits regulates the propagation of synaptic input, dendritic excitability, and synaptic plasticity in CA1 pyramidal neuron dendrites of the hippocampus. We report that the Ca2+ channel subunit Cav2.3 regulates IA in this cell type. We initially identified Cav2.3 as a Kv4.2-interacting protein in a proteomic screen and we confirmed Cav2.3-Kv4.2 complex association using multiple techniques. Functionally, Cav2.3 Ca2+-entry increases Kv4.2-mediated whole-cell current due to an increase in Kv4.2 surface expression. Using pharmacology and Cav2.3 knockout mice, we show that Cav2.3 regulates the dendritic gradient of IA. Furthermore, the loss of Cav2.3 function leads to the enhancement of AMPA receptor-mediated synaptic currents and NMDA receptor-mediated spine Ca2+ influx. These results propose that Cav2.3 and Kv4.2 are integral constituents of an ion channel complex that affects synaptic function in the hippocampus.
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Affiliation(s)
- Jonathan G Murphy
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jakob J Gutzmann
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lin Lin
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jiahua Hu
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Dax A Hoffman
- Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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3
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Welch MA, Jansen LAR, Baro DJ. SUMOylation of the Kv4.2 Ternary Complex Increases Surface Expression and Current Amplitude by Reducing Internalization in HEK 293 Cells. Front Mol Neurosci 2021; 14:757278. [PMID: 34795560 PMCID: PMC8593141 DOI: 10.3389/fnmol.2021.757278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/05/2021] [Indexed: 11/29/2022] Open
Abstract
Kv4 α-subunits exist as ternary complexes (TC) with potassium channel interacting proteins (KChIP) and dipeptidyl peptidase-like proteins (DPLP); multiple ancillary proteins also interact with the α-subunits throughout the channel’s lifetime. Dynamic regulation of Kv4.2 protein interactions adapts the transient potassium current, IA, mediated by Kv4 α-subunits. Small ubiquitin-like modifier (SUMO) is an 11 kD peptide post-translationally added to lysine (K) residues to regulate protein–protein interactions. We previously demonstrated that when expressed in human embryonic kidney (HEK) cells, Kv4.2 can be SUMOylated at two K residues, K437 and K579. SUMOylation at K437 increased surface expression of electrically silent channels while SUMOylation at K579 reduced IA maximal conductance (Gmax) without altering surface expression. KChIP and DPLP subunits are known to modify the pattern of Kv4.2 post-translational decorations and/or their effects. In this study, co-expressing Kv4.2 with KChIP2a and DPP10c altered the effects of enhanced Kv4.2 SUMOylation. First, the effect of enhanced SUMOylation was the same for a TC containing either the wild-type Kv4.2 or the mutant K437R Kv4.2, suggesting that either the experimental manipulation no longer enhanced K437 SUMOylation or K437 SUMOylation no longer influenced Kv4.2 surface expression. Second, instead of decreasing IA Gmax, enhanced SUMOylation at K579 now produced a significant ∼37–70% increase in IA maximum conductance (Gmax) and a significant ∼30–50% increase in Kv4.2g surface expression that was accompanied by a 65% reduction in TC internalization. Blocking clathrin-mediated endocytosis (CME) in HEK cells expressing the Kv4.2 TC mimicked and occluded the effect of SUMO on IA Gmax; however, the amount of Kv4.2 associated with the major adaptor for constitutive CME, adaptor protein 2 (AP2), was not SUMO dependent. Thus, SUMOylation reduced Kv4.2 internalization by acting downstream of Kv4.2 recruitment into clathrin-coated pits. In sum, the two major findings of this study are: SUMOylation of Kv4.2 at K579 regulates TC internalization most likely by promoting channel recycling. Additionally, there is a reciprocity between Kv4.2 SUMOylation and the Kv4.2 interactome such that SUMOylation regulates the interactome and the interactome influences the pattern and effect of SUMOylation.
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Affiliation(s)
- Meghyn A Welch
- Department of Biology, Georgia State University, Atlanta, GA, United States
| | | | - Deborah J Baro
- Department of Biology, Georgia State University, Atlanta, GA, United States.,Neuroscience Institute, Georgia State University, Atlanta, GA, United States
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4
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Zhang Y, Tachtsidis G, Schob C, Koko M, Hedrich UBS, Lerche H, Lemke JR, Haeringen A, Ruivenkamp C, Prescott T, Tveten K, Gerstner T, Pruniski B, DiTroia S, VanNoy GE, Rehm HL, McLaughlin H, Bolz HJ, Zechner U, Bryant E, McDonough T, Kindler S, Bähring R. KCND2 variants associated with global developmental delay differentially impair Kv4.2 channel gating. Hum Mol Genet 2021; 30:2300-2314. [PMID: 34245260 DOI: 10.1093/hmg/ddab192] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 11/13/2022] Open
Abstract
Here, we report on six unrelated individuals, all presenting with early-onset global developmental delay, associated with impaired motor, speech and cognitive development, partly with developmental epileptic encephalopathy and physical dysmorphisms. All individuals carry heterozygous missense variants of KCND2, which encodes the voltage-gated potassium (Kv) channel α-subunit Kv4.2. The amino acid substitutions associated with the variants, p.(Glu323Lys) (E323K), p.(Pro403Ala) (P403A), p.(Val404Leu) (V404L) and p.(Val404Met) (V404M), affect sites known to be critical for channel gating. To unravel their likely pathogenicity, recombinant mutant channels were studied in the absence and presence of auxiliary β-subunits under two-electrode voltage-clamp in Xenopus oocytes. All channel mutants exhibited slowed and incomplete macroscopic inactivation, and the P403A variant in addition slowed activation. Co-expression of KChIP2 or DPP6 augmented the functional expression of both wild-type and mutant channels, however, the auxiliary β-subunit-mediated gating modifications differed from wild-type and among mutants. To simulate the putative setting in the affected individuals, heteromeric Kv4.2 channels (wild-type + mutant) were studied as ternary complexes (containing both KChIP2 and DPP6). In the heteromeric ternary configuration, the E323K variant exhibited only marginal functional alterations compared to homomeric wild-type ternary, compatible with mild loss-of-function. By contrast, the P403A, V404L and V404M variants displayed strong gating impairment in the heteromeric ternary configuration, compatible with loss or gain-of-function. Our results support the etiological involvement of Kv4.2 channel gating impairment in early-onset monogenic global developmental delay. In addition, they suggest that gain-of-function mechanisms associated with a substitution of V404 increase epileptic seizure susceptibility.
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Affiliation(s)
- Yongqiang Zhang
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany.,Southeast University, Nanjing, China
| | - Georgios Tachtsidis
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Claudia Schob
- Institute for Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Mahmoud Koko
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Ulrike B S Hedrich
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie-Institute for Clinical Brain Research, Tübingen, Germany
| | - Johannes R Lemke
- University Center for Rare Diseases, Institute for Human Genetics, University Hospital, Leipzig, Germany
| | - Arie Haeringen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Claudia Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Trine Prescott
- Department of Medical Genetics, Telemark Hospital Trust, Skien, Norway
| | - Kristian Tveten
- Department of Medical Genetics, Telemark Hospital Trust, Skien, Norway
| | - Thorsten Gerstner
- Department of Child Neurology and Rehabilitation and Department of Pediatrics, Hospital of Southern Norway, Arendal, Norway
| | - Brianna Pruniski
- Division of Genetics & Metabolism, Phoenix Children's Medical Group, Phoenix, AZ, USA
| | - Stephanie DiTroia
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Grace E VanNoy
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Heidi L Rehm
- Center for Mendelian Genomics and Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | | | - Hanno J Bolz
- Senckenberg Centre for Human Genetics, Frankfurt/Main, Germany.,Institute of Human Genetics, University Hospital of Cologne, Cologne, Germany
| | - Ulrich Zechner
- Senckenberg Centre for Human Genetics, Frankfurt/Main, Germany.,Institute of Human Genetics, University Medical Center Mainz, Mainz, Germany
| | - Emily Bryant
- Ann & Robert H Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg Scool of Medicine, Chicago, IL, USA
| | - Tiffani McDonough
- Ann & Robert H Lurie Children's Hospital of Chicago, Department of Pediatrics, Northwestern University Feinberg Scool of Medicine, Chicago, IL, USA
| | - Stefan Kindler
- Institute for Human Genetics, University Hospital Hamburg-Eppendorf, Hamburg, Germany
| | - Robert Bähring
- Institute for Cellular and Integrative Physiology, Center for Experimental Medicine, University Hospital Hamburg-Eppendorf, Hamburg, Germany
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5
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Duncan AL, Reddy T, Koldsø H, Hélie J, Fowler PW, Chavent M, Sansom MSP. Protein crowding and lipid complexity influence the nanoscale dynamic organization of ion channels in cell membranes. Sci Rep 2017; 7:16647. [PMID: 29192147 PMCID: PMC5709381 DOI: 10.1038/s41598-017-16865-6] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 11/15/2017] [Indexed: 01/07/2023] Open
Abstract
Cell membranes are crowded and complex environments. To investigate the effect of protein-lipid interactions on dynamic organization in mammalian cell membranes, we have performed coarse-grained molecular dynamics simulations containing >100 copies of an inwardly rectifying potassium (Kir) channel which forms specific interactions with the regulatory lipid phosphatidylinositol 4,5-bisphosphate (PIP2). The tendency of protein molecules to cluster has the effect of organizing the membrane into dynamic compartments. At the same time, the diversity of lipids present has a marked effect on the clustering behavior of ion channels. Sub-diffusion of proteins and lipids is observed. Protein crowding alters the sub-diffusive behavior of proteins and lipids such as PIP2 which interact tightly with Kir channels. Protein crowding also affects bilayer properties, such as membrane undulations and bending rigidity, in a PIP2-dependent manner. This interplay between the diffusion and the dynamic organization of Kir channels may have important implications for channel function.
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Affiliation(s)
- Anna L Duncan
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Tyler Reddy
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- T-6, MS K710, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Heidi Koldsø
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- D. E. Shaw Research, 120 W 45th St., New York, NY, 10036, USA
| | - Jean Hélie
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Semmle, Blue Boar Court, 9 Alfred St, Oxford, OX1 4EH, UK
| | - Philip W Fowler
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Matthieu Chavent
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- IPBS-CNRS, Toulouse, Midi-Pyrénées, France
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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6
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Abstract
Background: Potassium channels have been shown to be involved in neural plasticity and learning. Kv4.2 is a subunit of the A-type potassium channel. Kv4.2 channels modulate excitability in the dendrites of pyramidal neurons in the cortex and hippocampus. Deletion of Kv4.2 results in spatial learning and conditioned fear deficits; however, previous studies have only examined deletion of Kv4.2 in aversive learning tests. Methods: For the current study, we used the Lashley maze as an appetitive learning test. We examined Kv4.2 wildtype (WT) and knockout (KO) mice in the Lashley maze over 4 days during adulthood. The first day consisted of habituating the mice to the maze. The mice then received five trials per day for the next 3 days. The number of errors and the time to the goal box was recorded for each trial. The goal box contained a weigh boat with an appetitive reward (gelatin with sugar). There was an intertrial interval of 15 minutes. Results: We found that Kv4.2 KO mice committed more errors across the trials compared to the WT mice p<0.001. There was no difference in the latency to find the goal box over the period. Discussion: Our finding that deletion of Kv4.2 resulted in more errors in the Lashley maze across 15 trials contribute to a growing body of evidence that Kv4.2 channels are significantly involved in learning and memory.
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Affiliation(s)
- Gregory D Smith
- Institute of Biomedical Sciences, Baylor University, Waco, TX, 76798, USA
| | - Nan Gao
- Department of Psychology and Neuroscience, Baylor University, Waco, TX, 76798, USA
| | - Joaquin N Lugo
- Institute of Biomedical Sciences, Baylor University, Waco, TX, 76798, USA; Department of Psychology and Neuroscience, Baylor University, Waco, TX, 76798, USA
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7
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Smith GD, Gao N, Lugo JN. Kv4.2 knockout mice display learning and memory deficits in the Lashley maze. F1000Res 2016; 5:2456. [PMID: 28163893 PMCID: PMC5247778 DOI: 10.12688/f1000research.9664.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/24/2017] [Indexed: 09/10/2023] Open
Abstract
Background: Potassium channels have been shown to be involved in neural plasticity and learning. Kv4.2 is a subunit of the A-type potassium channel. Kv4.2 channels modulate excitability in the dendrites of pyramidal neurons in the cortex and hippocampus. Deletion of Kv4.2 results in spatial learning and conditioned fear deficits; however, previous studies have only examined deletion of Kv4.2 in aversive learning tests. Methods: For the current study, we used the Lashley maze as an appetitive learning test. We examined Kv4.2 wildtype (WT) and knockout (KO) mice in the Lashley maze over 4 days during adulthood. The first day consisted of habituating the mice to the maze. The mice then received five trials per day for the next 3 days. The number of errors and the time to the goal box was recorded for each trial. The goal box contained a weigh boat with an appetitive reward (gelatin with sugar). There was an intertrial interval of 15 minutes. Results: We found that Kv4.2 KO mice committed more errors across the trials compared to the WT mice p<0.001. There was no difference in the latency to find the goal box over the period. Discussion: Our finding that deletion of Kv4.2 resulted in more errors in the Lashley maze across 15 trials contribute to a growing body of evidence that Kv4.2 channels are significantly involved in learning and memory.
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Affiliation(s)
- Gregory D. Smith
- Institute of Biomedical Sciences, Baylor University, Waco, TX, 76798, USA
| | - Nan Gao
- Department of Psychology and Neuroscience, Baylor University, Waco, TX, 76798, USA
| | - Joaquin N. Lugo
- Institute of Biomedical Sciences, Baylor University, Waco, TX, 76798, USA
- Department of Psychology and Neuroscience, Baylor University, Waco, TX, 76798, USA
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Matsumoto M, Hiyama TY, Kuboyama K, Suzuki R, Fujikawa A, Noda M. Channel properties of Nax expressed in neurons. PLoS One 2015; 10:e0126109. [PMID: 25961826 PMCID: PMC4427406 DOI: 10.1371/journal.pone.0126109] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 03/19/2015] [Indexed: 12/19/2022] Open
Abstract
Nax is a sodium-concentration ([Na+])-sensitive Na channel with a gating threshold of ~150 mM for extracellular [Na+] ([Na+]o) in vitro. We previously reported that Nax was preferentially expressed in the glial cells of sensory circumventricular organs including the subfornical organ, and was involved in [Na+] sensing for the control of salt-intake behavior. Although Nax was also suggested to be expressed in the neurons of some brain regions including the amygdala and cerebral cortex, the channel properties of Nax have not yet been adequately characterized in neurons. We herein verified that Nax was expressed in neurons in the lateral amygdala of mice using an antibody that was newly generated against mouse Nax. To investigate the channel properties of Nax expressed in neurons, we established an inducible cell line of Nax using the mouse neuroblastoma cell line, Neuro-2a, which is endogenously devoid of the expression of Nax. Functional analyses of this cell line revealed that the [Na+]-sensitivity of Nax in neuronal cells was similar to that expressed in glial cells. The cation selectivity sequence of the Nax channel in cations was revealed to be Na+ ≈ Li+ > Rb+ > Cs+ for the first time. Furthermore, we demonstrated that Nax bound to postsynaptic density protein 95 (PSD95) through its PSD95/Disc-large/ZO-1 (PDZ)-binding motif at the C-terminus in neurons. The interaction between Nax and PSD95 may be involved in promoting the surface expression of Nax channels because the depletion of endogenous PSD95 resulted in a decrease in Nax at the plasma membrane. These results indicated, for the first time, that Nax functions as a [Na+]-sensitive Na channel in neurons as well as in glial cells.
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Affiliation(s)
- Masahito Matsumoto
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Japan
| | - Takeshi Y. Hiyama
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Japan
- School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
| | - Kazuya Kuboyama
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Japan
| | - Ryoko Suzuki
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Japan
| | - Akihiro Fujikawa
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Japan
| | - Masaharu Noda
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Japan
- School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Japan
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9
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DPP6 gene disruption in a family with Gilles de la Tourette syndrome. Neurogenetics 2014; 15:237-42. [DOI: 10.1007/s10048-014-0418-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 08/08/2014] [Indexed: 01/04/2023]
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10
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Chen T, Gai WP, Abbott CA. Dipeptidyl peptidase 10 (DPP10(789)): a voltage gated potassium channel associated protein is abnormally expressed in Alzheimer's and other neurodegenerative diseases. BIOMED RESEARCH INTERNATIONAL 2014; 2014:209398. [PMID: 25025038 PMCID: PMC4084682 DOI: 10.1155/2014/209398] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 04/23/2014] [Indexed: 12/15/2022]
Abstract
The neuropathological features associated with Alzheimer's disease (AD) include the presence of extracellular amyloid-β peptide-containing plaques and intracellular tau positive neurofibrillary tangles and the loss of synapses and neurons in defined regions of the brain. Dipeptidyl peptidase 10 (DPP10) is a protein that facilitates Kv4 channel surface expression and neuronal excitability. This study aims to explore DPP10789 protein distribution in human brains and its contribution to the neurofibrillary pathology of AD and other tauopathies. Immunohistochemical analysis revealed predominant neuronal staining of DPP10789 in control brains, and the CA1 region of the hippocampus contained strong reactivity in the distal dendrites of the pyramidal cells. In AD brains, robust DPP10789 reactivity was detected in neurofibrillary tangles and plaque-associated dystrophic neurites, most of which colocalized with the doubly phosphorylated Ser-202/Thr-205 tau epitope. DPP10789 positive neurofibrillary tangles and plaque-associated dystrophic neurites also appeared in other neurodegenerative diseases such as frontotemporal lobar degeneration, diffuse Lewy body disease, and progressive supranuclear palsy. Occasional DPP10789 positive neurofibrillary tangles and neurites were seen in some aged control brains. Western blot analysis showed both full length and truncated DPP10789 fragments with the later increasing significantly in AD brains compared to control brains. Our results suggest that DPP10789 is involved in the pathology of AD and other neurodegenerative diseases.
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Affiliation(s)
- Tong Chen
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Wei-Ping Gai
- Department of Human Physiology, School of Medicine, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Catherine A. Abbott
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
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11
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Jerng HH, Pfaffinger PJ. Modulatory mechanisms and multiple functions of somatodendritic A-type K (+) channel auxiliary subunits. Front Cell Neurosci 2014; 8:82. [PMID: 24723849 PMCID: PMC3973911 DOI: 10.3389/fncel.2014.00082] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/03/2014] [Indexed: 12/13/2022] Open
Abstract
Auxiliary subunits are non-conducting, modulatory components of the multi-protein ion channel complexes that underlie normal neuronal signaling. They interact with the pore-forming α-subunits to modulate surface distribution, ion conductance, and channel gating properties. For the somatodendritic subthreshold A-type potassium (ISA) channel based on Kv4 α-subunits, two types of auxiliary subunits have been extensively studied: Kv channel-interacting proteins (KChIPs) and dipeptidyl peptidase-like proteins (DPLPs). KChIPs are cytoplasmic calcium-binding proteins that interact with intracellular portions of the Kv4 subunits, whereas DPLPs are type II transmembrane proteins that associate with the Kv4 channel core. Both KChIPs and DPLPs genes contain multiple start sites that are used by various neuronal populations to drive the differential expression of functionally distinct N-terminal variants. In turn, these N-terminal variants generate tremendous functional diversity across the nervous system. Here, we focus our review on (1) the molecular mechanism underlying the unique properties of different N-terminal variants, (2) the shaping of native ISA properties by the concerted actions of KChIPs and DPLP variants, and (3) the surprising ways that KChIPs and DPLPs coordinate the activity of multiple channels to fine-tune neuronal excitability. Unlocking the unique contributions of different auxiliary subunit N-terminal variants may provide an important opportunity to develop novel targeted therapeutics to treat numerous neurological disorders.
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Affiliation(s)
- Henry H. Jerng
- Department of Neuroscience, Baylor College of MedicineHouston, TX, USA
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12
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Proepper C, Putz S, Russell R, Boeckers TM, Liebau S. The Kvβ2 subunit of voltage-gated potassium channels is interacting with ProSAP2/Shank3 in the PSD. Neuroscience 2013; 261:133-43. [PMID: 24211303 DOI: 10.1016/j.neuroscience.2013.10.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 01/18/2023]
Abstract
The postsynaptic density is an electron dense meshwork composed of a variety of molecules facilitating neuronal signal transmission. ProSAP2/Shank3 represents a crucial player at postsynaptic sites, assembling large multimeric platforms and anchoring numerous other molecules, thereby linking the functional synapse with the cytoskeleton. ProSAP2/Shank3 is also implicated in the pathogenesis of numerous diseases, including autism spectrum disorders. KvBeta2 (Kvβ2) on the other hand serves as a regulatory subunit of voltage-gated potassium channels. Kvβ2 is located at various sites in the neuron including the axon (binding to Kv1.2), the dendrites (binding to Kv4.2) and the synapse. Binding of Kvβ2 to either Kv1.2 or Kv4 modulates not only the channel conformation but directs targeting of the channel protein complex to distinct loci within the cell. Thus an interaction between ProSAP2 and Kvβ2 could have important roles at diverse cellular compartments and moreover during maturation stages. We report here on the direct protein-protein interaction of the postsynaptic density anchoring molecule ProSAP2 and the potassium channel subunit Kvβ2, initially identified in a yeast-two-hybrid-screen. Furthermore, we characterize this interaction at synapses using primary hippocampal neurons in vitro.
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Affiliation(s)
- C Proepper
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - S Putz
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - R Russell
- Department of Internal Medicine 1, Ulm University Hospital, Ulm, Germany
| | - T M Boeckers
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany
| | - S Liebau
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany; Institute of Neuroanatomy, University of Tuebingen, Tuebingen, Germany.
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13
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Bavassano C, Marvaldi L, Langeslag M, Sarg B, Lindner H, Klimaschewski L, Kress M, Ferrer-Montiel A, Knaus HG. Identification of voltage-gated K(+) channel beta 2 (Kvβ2) subunit as a novel interaction partner of the pain transducer Transient Receptor Potential Vanilloid 1 channel (TRPV1). BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3166-3175. [PMID: 24036102 DOI: 10.1016/j.bbamcr.2013.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/02/2013] [Accepted: 09/03/2013] [Indexed: 11/26/2022]
Abstract
The Transient Receptor Potential Vanilloid 1 (TRPV1, vanilloid receptor 1) ion channel plays a key role in the perception of thermal and inflammatory pain, however, its molecular environment in dorsal root ganglia (DRG) is largely unexplored. Utilizing a panel of sequence-directed antibodies against TRPV1 protein and mouse DRG membranes, the channel complex from mouse DRG was detergent-solubilized, isolated by immunoprecipitation and subsequently analyzed by mass spectrometry. A number of potential TRPV1 interaction partners were identified, among them cytoskeletal proteins, signal transduction molecules, and established ion channel subunits. Based on stringent specificity criteria, the voltage-gated K(+) channel beta 2 subunit (Kvβ2), an accessory subunit of voltage-gated K(+) channels, was identified of being associated with native TRPV1 channels. Reverse co-immunoprecipitation and antibody co-staining experiments confirmed TRPV1/Kvβ2 association. Biotinylation assays in the presence of Kvβ2 demonstrated increased cell surface expression levels of TRPV1, while patch-clamp experiments resulted in a significant increase of TRPV1 sensitivity to capsaicin. Our work shows, for the first time, the association of a Kvβ subunit with TRPV1 channels, and suggests that such interaction may play a role in TRPV1 channel trafficking to the plasma membrane.
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Affiliation(s)
- Carlo Bavassano
- Division of Cellular and Molecular Pharmacology, Medical University Innsbruck, Peter-Mayr strasse 1, 6020 Innsbruck, Austria.
| | - Letizia Marvaldi
- Division of Neuroanatomy, Medical University Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria.
| | - Michiel Langeslag
- Division of Physiology, Medical University Innsbruck, Fritz-Pregl-Straße 3, 6020 Innsbruck, Austria.
| | - Bettina Sarg
- Division of Clinical Biochemistry, Medical University Innsbruck, Innrain 80, 6020 Innsbruck, Austria.
| | - Herbert Lindner
- Division of Clinical Biochemistry, Medical University Innsbruck, Innrain 80, 6020 Innsbruck, Austria.
| | - Lars Klimaschewski
- Division of Neuroanatomy, Medical University Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria.
| | - Michaela Kress
- Division of Physiology, Medical University Innsbruck, Fritz-Pregl-Straße 3, 6020 Innsbruck, Austria.
| | - Antonio Ferrer-Montiel
- IBMC, Universidad Miguel Hernandez Elche, Av. de la Universidad s/n., Edif. Torregaitán, E-03202, Spain.
| | - Hans-Günther Knaus
- Division of Cellular and Molecular Pharmacology, Medical University Innsbruck, Peter-Mayr strasse 1, 6020 Innsbruck, Austria.
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14
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Lee TT, Zhang XD, Chuang CC, Chen JJ, Chen YA, Chen SC, Chen TY, Tang CY. Myotonia congenita mutation enhances the degradation of human CLC-1 chloride channels. PLoS One 2013; 8:e55930. [PMID: 23424641 PMCID: PMC3570542 DOI: 10.1371/journal.pone.0055930] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/03/2013] [Indexed: 11/18/2022] Open
Abstract
Myotonia congenita is a hereditary muscle disorder caused by mutations in the human voltage-gated chloride (Cl−) channel CLC-1. Myotonia congenita can be inherited in an autosomal recessive (Becker type) or dominant (Thomsen type) fashion. One hypothesis for myotonia congenita is that the inheritance pattern of the disease is determined by the functional consequence of the mutation on the gating of CLC-1 channels. Several disease-related mutations, however, have been shown to yield functional CLC-1 channels with no detectable gating defects. In this study, we have functionally and biochemically characterized a myotonia mutant: A531V. Despite a gating property similar to that of wild-type (WT) channels, the mutant CLC-1 channel displayed a diminished whole-cell current density and a reduction in the total protein expression level. Our biochemical analyses further demonstrated that the reduced expression of A531V can be largely attributed to an enhanced proteasomal degradation as well as a defect in protein trafficking to surface membranes. Moreover, the A531V mutant protein also appeared to be associated with excessive endosomal-lysosomal degradation. Neither the reduced protein expression nor the diminished current density was rescued by incubating A531V-expressing cells at 27°C. These results demonstrate that the molecular pathophysiology of A531V does not involve anomalous channel gating, but rather a disruption of the balance between the synthesis and degradation of the CLC-1 channel protein.
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Affiliation(s)
- Ting-Ting Lee
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Xiao-Dong Zhang
- Neuroscience Center, University of California Davis, Davis, California, United States of America
| | - Chao-Chin Chuang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Jing-Jer Chen
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-An Chen
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shu-Ching Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Tsung-Yu Chen
- Neuroscience Center, University of California Davis, Davis, California, United States of America
| | - Chih-Yung Tang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail:
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15
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Casey JP, Magalhaes T, Conroy JM, Regan R, Shah N, Anney R, Shields DC, Abrahams BS, Almeida J, Bacchelli E, Bailey AJ, Baird G, Battaglia A, Berney T, Bolshakova N, Bolton PF, Bourgeron T, Brennan S, Cali P, Correia C, Corsello C, Coutanche M, Dawson G, de Jonge M, Delorme R, Duketis E, Duque F, Estes A, Farrar P, Fernandez BA, Folstein SE, Foley S, Fombonne E, Freitag CM, Gilbert J, Gillberg C, Glessner JT, Green J, Guter SJ, Hakonarson H, Holt R, Hughes G, Hus V, Igliozzi R, Kim C, Klauck SM, Kolevzon A, Lamb JA, Leboyer M, Le Couteur A, Leventhal BL, Lord C, Lund SC, Maestrini E, Mantoulan C, Marshall CR, McConachie H, McDougle CJ, McGrath J, McMahon WM, Merikangas A, Miller J, Minopoli F, Mirza GK, Munson J, Nelson SF, Nygren G, Oliveira G, Pagnamenta AT, Papanikolaou K, Parr JR, Parrini B, Pickles A, Pinto D, Piven J, Posey DJ, Poustka A, Poustka F, Ragoussis J, Roge B, Rutter ML, Sequeira AF, Soorya L, Sousa I, Sykes N, Stoppioni V, Tancredi R, Tauber M, Thompson AP, Thomson S, Tsiantis J, Van Engeland H, Vincent JB, Volkmar F, Vorstman JAS, Wallace S, Wang K, Wassink TH, White K, Wing K, Wittemeyer K, Yaspan BL, Zwaigenbaum L, Betancur C, Buxbaum JD, Cantor RM, Cook EH, Coon H, Cuccaro ML, Geschwind DH, Haines JL, Hallmayer J, Monaco AP, Nurnberger JI, Pericak-Vance MA, Schellenberg GD, Scherer SW, Sutcliffe JS, Szatmari P, Vieland VJ, Wijsman EM, Green A, Gill M, Gallagher L, Vicente A, Ennis S. A novel approach of homozygous haplotype sharing identifies candidate genes in autism spectrum disorder. Hum Genet 2012; 131:565-79. [PMID: 21996756 PMCID: PMC3303079 DOI: 10.1007/s00439-011-1094-6] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 09/15/2011] [Indexed: 01/18/2023]
Abstract
Autism spectrum disorder (ASD) is a highly heritable disorder of complex and heterogeneous aetiology. It is primarily characterized by altered cognitive ability including impaired language and communication skills and fundamental deficits in social reciprocity. Despite some notable successes in neuropsychiatric genetics, overall, the high heritability of ASD (~90%) remains poorly explained by common genetic risk variants. However, recent studies suggest that rare genomic variation, in particular copy number variation, may account for a significant proportion of the genetic basis of ASD. We present a large scale analysis to identify candidate genes which may contain low-frequency recessive variation contributing to ASD while taking into account the potential contribution of population differences to the genetic heterogeneity of ASD. Our strategy, homozygous haplotype (HH) mapping, aims to detect homozygous segments of identical haplotype structure that are shared at a higher frequency amongst ASD patients compared to parental controls. The analysis was performed on 1,402 Autism Genome Project trios genotyped for 1 million single nucleotide polymorphisms (SNPs). We identified 25 known and 1,218 novel ASD candidate genes in the discovery analysis including CADM2, ABHD14A, CHRFAM7A, GRIK2, GRM3, EPHA3, FGF10, KCND2, PDZK1, IMMP2L and FOXP2. Furthermore, 10 of the previously reported ASD genes and 300 of the novel candidates identified in the discovery analysis were replicated in an independent sample of 1,182 trios. Our results demonstrate that regions of HH are significantly enriched for previously reported ASD candidate genes and the observed association is independent of gene size (odds ratio 2.10). Our findings highlight the applicability of HH mapping in complex disorders such as ASD and offer an alternative approach to the analysis of genome-wide association data.
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Affiliation(s)
- Jillian P. Casey
- School of Medicine and Medical Science University College, Dublin 4, Ireland
| | - Tiago Magalhaes
- Instituto Nacional de Saude Dr Ricardo Jorge, Av Padre Cruz 1649-016, Lisbon, Portugal
- BioFIG, Center for Biodiversity, Functional and Integrative Genomics, Campus da FCUL, C2.2.12, Campo Grande, 1749-016 Lisbon, Portugal
- Instituto Gulbenkian de Cîencia, Rua Quinta Grande, 2780-156 Oeiras, Portugal
| | - Judith M. Conroy
- School of Medicine and Medical Science University College, Dublin 4, Ireland
| | - Regina Regan
- School of Medicine and Medical Science University College, Dublin 4, Ireland
| | - Naisha Shah
- School of Medicine and Medical Science University College, Dublin 4, Ireland
| | - Richard Anney
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - Denis C. Shields
- School of Medicine and Medical Science University College, Dublin 4, Ireland
| | - Brett S. Abrahams
- Department of Neurology, Center for Autism Research and Treatment, Program in Neurogenetics, Semel Institute, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - Joana Almeida
- Hospital Pediátrico de Coimbra, 3000–076 Coimbra, Portugal
| | - Elena Bacchelli
- Department of Biology, University of Bologna, 40126 Bologna, Italy
| | - Anthony J. Bailey
- Department of Psychiatry, University of British Columbia, Vancouver, V6T 2A1 Canada
| | | | - Agatino Battaglia
- Stella Maris Institute for Child and Adolescent Neuropsychiatry, 56128 Calambrone, Pisa, Italy
| | - Tom Berney
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
- Institute of Health and Society, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
| | - Nadia Bolshakova
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - Patrick F. Bolton
- Department of Child and Adolescent Psychiatry, Institute of Psychiatry, London, SE5 8AF UK
| | - Thomas Bourgeron
- Department of Human Genetics and Cognitive Functions, Institut Pasteur, University Paris Diderot-Paris 7, CNRS URA 2182, Fondation FondaMental, 75015 Paris, France
| | - Sean Brennan
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - Phil Cali
- Department of Psychiatry, Institute for Juvenile Research, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Catarina Correia
- Instituto Nacional de Saude Dr Ricardo Jorge, Av Padre Cruz 1649-016, Lisbon, Portugal
- BioFIG, Center for Biodiversity, Functional and Integrative Genomics, Campus da FCUL, C2.2.12, Campo Grande, 1749-016 Lisbon, Portugal
- Instituto Gulbenkian de Cîencia, Rua Quinta Grande, 2780-156 Oeiras, Portugal
| | - Christina Corsello
- Autism and Communicative Disorders Centre, University of Michigan, Ann Arbor, MI 48109-2054 USA
| | - Marc Coutanche
- Department of Psychiatry, University of Oxford, Warneford Hospital, Headington, Oxford, OX3 7JX UK
| | - Geraldine Dawson
- Autism Speaks, New York, 10016 USA
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC 27599-3366 USA
| | - Maretha de Jonge
- Department of Child and Adolescent Psychiatry, University Medical Center, 3508 Utrecht, GA The Netherlands
| | - Richard Delorme
- INSERM U 955, Fondation FondaMental, APHP, Hôpital Robert Debré, Child and Adolescent Psychiatry, 75019 Paris, France
| | - Eftichia Duketis
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, J.W. Goethe University Frankfurt, 60528 Frankfurt, Germany
| | | | - Annette Estes
- Department of Speech and Hearing Sciences, University of Washington, Seattle, WA 98195 USA
| | - Penny Farrar
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - Bridget A. Fernandez
- Disciplines of Genetics and Medicine, Memorial University of Newfoundland, St John’s Newfoundland, A1B 3V6 Canada
| | - Susan E. Folstein
- Department of Psychiatry, University of Miami School of Medicine, Miami, FL 33136 USA
| | - Suzanne Foley
- Department of Psychiatry, University of Oxford, Warneford Hospital, Headington, Oxford, OX3 7JX UK
| | - Eric Fombonne
- Division of Psychiatry, McGill University, Montreal, QC H3A 1A1 Canada
| | - Christine M. Freitag
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, J.W. Goethe University Frankfurt, 60528 Frankfurt, Germany
| | - John Gilbert
- The John P. Hussman Institute for Human Genomics, University of Miami School of Medicine, Miami, FL 33136 USA
| | - Christopher Gillberg
- Gillberg Neuropsychiatry Centre, Sahlgrenska Academy, University of Gothenburg, S41345 Gothenburg, Sweden
| | - Joseph T. Glessner
- The Center for Applied Genomics, Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 USA
| | - Jonathan Green
- Academic Department of Child Psychiatry, Booth Hall of Children’s Hospital, Blackley, Manchester, M9 7AA UK
| | - Stephen J. Guter
- Department of Psychiatry, Institute for Juvenile Research, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Hakon Hakonarson
- The Center for Applied Genomics, Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 USA
- Department of Pediatrics, Children’s Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA 19104 USA
| | - Richard Holt
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - Gillian Hughes
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - Vanessa Hus
- Autism and Communicative Disorders Centre, University of Michigan, Ann Arbor, MI 48109-2054 USA
| | - Roberta Igliozzi
- Stella Maris Institute for Child and Adolescent Neuropsychiatry, 56128 Calambrone, Pisa, Italy
| | - Cecilia Kim
- The Center for Applied Genomics, Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 USA
| | - Sabine M. Klauck
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Alexander Kolevzon
- Department of Psychiatry, The Seaver Autism Center for Research and Treatment, Mount Sinai School of Medicine, New York, 10029 USA
| | - Janine A. Lamb
- Centre for Integrated Genomic Medical Research, University of Manchester, Manchester, M13 9PT UK
| | - Marion Leboyer
- INSERM U995, Department of Psychiatry, Groupe Hospitalier Henri Mondor-Albert Chenevier, AP-HP, University Paris 12, Fondation FondaMental, 94000 Créteil, France
| | - Ann Le Couteur
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
- Institute of Health and Society, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
| | - Bennett L. Leventhal
- Nathan Kline Institute for Psychiatric Research (NKI), 140 Old Orangeburg Road, Orangeburg, NY 10962 USA
- Department of Child and Adolescent Psychiatry, New York University, NYU Child Study Center, 550 First Avenue, New York, NY 10016 USA
| | - Catherine Lord
- Autism and Communicative Disorders Centre, University of Michigan, Ann Arbor, MI 48109-2054 USA
| | - Sabata C. Lund
- Department of Molecular Physiology and Biophysics, Vanderbilt Kennedy Center, Centers for Human Genetics Research and Molecular Neuroscience, Vanderbilt University, Nashville, TN 37232 USA
| | - Elena Maestrini
- Department of Biology, University of Bologna, 40126 Bologna, Italy
| | - Carine Mantoulan
- Octogone/CERPP (Centre d’Eudes et de Recherches en Psychopathologie), University de Toulouse Le Mirail, 31058 Toulouse Cedex, France
| | - Christian R. Marshall
- The Centre for Applied Genomics and Program in Genetics and Genomic Biology, The Hospital for Sick Children, Toronto, ON M5G 1L7 Canada
| | - Helen McConachie
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
- Institute of Health and Society, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
| | | | - Jane McGrath
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - William M. McMahon
- Psychiatry Department, University of Utah Medical School, Salt Lake City, UT 84108 USA
| | - Alison Merikangas
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - Judith Miller
- Psychiatry Department, University of Utah Medical School, Salt Lake City, UT 84108 USA
| | | | - Ghazala K. Mirza
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - Jeff Munson
- Department of Psychiatry and Behavioural Sciences, University of Washington, Seattle, WA 98195 USA
| | - Stanley F. Nelson
- Department of Human Genetics, University of California, Los Angeles School of Medicine, Los Angeles, CA 90095 USA
| | - Gudrun Nygren
- Gillberg Neuropsychiatry Centre, Sahlgrenska Academy, University of Gothenburg, S41345 Gothenburg, Sweden
| | | | | | - Katerina Papanikolaou
- University Department of Child Psychiatry, Athens University, Medical School, Agia Sophia Children’s Hospital, 115 27 Athens, Greece
| | - Jeremy R. Parr
- Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
- Institute of Health and Society, Newcastle University, Newcastle Upon Tyne, NE1 7RU UK
| | - Barbara Parrini
- Stella Maris Institute for Child and Adolescent Neuropsychiatry, 56128 Calambrone, Pisa, Italy
| | - Andrew Pickles
- Department of Medicine, School of Epidemiology and Health Science, University of Manchester, Manchester, M13 9PT UK
| | - Dalila Pinto
- The Centre for Applied Genomics and Program in Genetics and Genomic Biology, The Hospital for Sick Children, Toronto, ON M5G 1L7 Canada
| | - Joseph Piven
- Carolina Institute for Developmental Disabilities, CB3366, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3366 USA
| | - David J. Posey
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202 USA
| | - Annemarie Poustka
- Division of Molecular Genome Analysis, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Fritz Poustka
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, J.W. Goethe University Frankfurt, 60528 Frankfurt, Germany
| | - Jiannis Ragoussis
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - Bernadette Roge
- Octogone/CERPP (Centre d’Eudes et de Recherches en Psychopathologie), University de Toulouse Le Mirail, 31058 Toulouse Cedex, France
| | - Michael L. Rutter
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, London, SE5 8AF UK
| | - Ana F. Sequeira
- Instituto Nacional de Saude Dr Ricardo Jorge, Av Padre Cruz 1649-016, Lisbon, Portugal
- BioFIG, Center for Biodiversity, Functional and Integrative Genomics, Campus da FCUL, C2.2.12, Campo Grande, 1749-016 Lisbon, Portugal
- Instituto Gulbenkian de Cîencia, Rua Quinta Grande, 2780-156 Oeiras, Portugal
| | - Latha Soorya
- Department of Psychiatry, The Seaver Autism Center for Research and Treatment, Mount Sinai School of Medicine, New York, 10029 USA
| | - Inês Sousa
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - Nuala Sykes
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - Vera Stoppioni
- Neuropsichiatria Infantile, Ospedale Santa Croce, 61032 Fano, Italy
| | - Raffaella Tancredi
- Stella Maris Institute for Child and Adolescent Neuropsychiatry, 56128 Calambrone, Pisa, Italy
| | - Maïté Tauber
- Octogone/CERPP (Centre d’Eudes et de Recherches en Psychopathologie), University de Toulouse Le Mirail, 31058 Toulouse Cedex, France
| | - Ann P. Thompson
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON L8N 3Z5 Canada
| | - Susanne Thomson
- Department of Molecular Physiology and Biophysics, Vanderbilt Kennedy Center, Centers for Human Genetics Research and Molecular Neuroscience, Vanderbilt University, Nashville, TN 37232 USA
| | - John Tsiantis
- University Department of Child Psychiatry, Athens University, Medical School, Agia Sophia Children’s Hospital, 115 27 Athens, Greece
| | - Herman Van Engeland
- Department of Child and Adolescent Psychiatry, University Medical Center, 3508 Utrecht, GA The Netherlands
| | - John B. Vincent
- Department of Psychiatry, Centre for Addiction and Mental Health, Clarke Institute, University of Toronto, Toronto, ON M5G 1X8 Canada
| | - Fred Volkmar
- Child Study Centre, Yale University, New Haven, CT 06520 USA
| | - Jacob A. S. Vorstman
- Department of Child and Adolescent Psychiatry, University Medical Center, 3508 Utrecht, GA The Netherlands
| | - Simon Wallace
- Department of Psychiatry, University of Oxford, Warneford Hospital, Headington, Oxford, OX3 7JX UK
| | - Kai Wang
- The Center for Applied Genomics, Division of Human Genetics, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 USA
| | - Thomas H. Wassink
- Department of Psychiatry, Carver College of Medicine, Iowa City, IA 52242 USA
| | - Kathy White
- Department of Psychiatry, University of Oxford, Warneford Hospital, Headington, Oxford, OX3 7JX UK
| | - Kirsty Wing
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - Kerstin Wittemeyer
- Autism Centre for Education and Research, School of Education, University of Birmingham, Birmingham, B15 2TT UK
| | - Brian L. Yaspan
- Department of Molecular Physiology and Biophysics, Vanderbilt Kennedy Center, Centers for Human Genetics Research and Molecular Neuroscience, Vanderbilt University, Nashville, TN 37232 USA
| | - Lonnie Zwaigenbaum
- Department of Pediatrics, University of Alberta, Edmonton, AB T6G 2J3 Canada
| | - Catalina Betancur
- INSERM U952 and CNRS UMR 7224, UPMC Univ Paris 06, Paris, 75005 France
| | - Joseph D. Buxbaum
- Department of Psychiatry, The Seaver Autism Center for Research and Treatment, Mount Sinai School of Medicine, New York, 10029 USA
- Departments of Genetics and Genomic Sciences and Neuroscience, Mount Sinai School of Medicine, New York, 10029 USA
- Department of Neuroscience, Mount Sinai School of Medicine, New York, 10029 USA
| | - Rita M. Cantor
- Department of Human Genetics, University of California, Los Angeles School of Medicine, Los Angeles, CA 90095 USA
| | - Edwin H. Cook
- Department of Psychiatry, Institute for Juvenile Research, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Hilary Coon
- Psychiatry Department, University of Utah Medical School, Salt Lake City, UT 84108 USA
| | - Michael L. Cuccaro
- The John P. Hussman Institute for Human Genomics, University of Miami School of Medicine, Miami, FL 33136 USA
| | - Daniel H. Geschwind
- Department of Neurology, Center for Autism Research and Treatment, Program in Neurogenetics, Semel Institute, David Geffen School of Medicine at UCLA, Los Angeles, USA
| | - Jonathan L. Haines
- Department of Molecular Physiology and Biophysics, Vanderbilt Kennedy Center, Centers for Human Genetics Research and Molecular Neuroscience, Vanderbilt University, Nashville, TN 37232 USA
| | - Joachim Hallmayer
- Department of Psychiatry, Division of Child and Adolescent Psychiatry and Child Development, Stanford University School of Medicine, Stanford, CA 94304 USA
| | - Anthony P. Monaco
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN UK
| | - John I. Nurnberger
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202 USA
| | - Margaret A. Pericak-Vance
- The John P. Hussman Institute for Human Genomics, University of Miami School of Medicine, Miami, FL 33136 USA
| | - Gerard D. Schellenberg
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Pennsylvania, 19104 USA
| | - Stephen W. Scherer
- The Centre for Applied Genomics and Program in Genetics and Genomic Biology, The Hospital for Sick Children, Toronto, ON M5G 1L7 Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1 Canada
| | - James S. Sutcliffe
- Department of Molecular Physiology and Biophysics, Vanderbilt Kennedy Center, Centers for Human Genetics Research and Molecular Neuroscience, Vanderbilt University, Nashville, TN 37232 USA
| | - Peter Szatmari
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON L8N 3Z5 Canada
| | - Veronica J. Vieland
- Battelle Center for Mathematical Medicine, The Research Institute at Nationwide Children’s Hospital and The Ohio State University, Columbus, OH 43205 USA
| | - Ellen M. Wijsman
- Department of Biostatistics, University of Washington, Seattle, WA 98195 USA
- Department of Medicine, University of Washington, Seattle, WA 98195 USA
| | - Andrew Green
- School of Medicine and Medical Science University College, Dublin 4, Ireland
| | - Michael Gill
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - Louise Gallagher
- Autism Genetics Group, Department of Psychiatry, School of Medicine, Trinity College, Dublin 8, Ireland
| | - Astrid Vicente
- Instituto Nacional de Saude Dr Ricardo Jorge, Av Padre Cruz 1649-016, Lisbon, Portugal
- BioFIG, Center for Biodiversity, Functional and Integrative Genomics, Campus da FCUL, C2.2.12, Campo Grande, 1749-016 Lisbon, Portugal
- Instituto Gulbenkian de Cîencia, Rua Quinta Grande, 2780-156 Oeiras, Portugal
| | - Sean Ennis
- School of Medicine and Medical Science University College, Dublin 4, Ireland
- Health Sciences Centre, University College Dublin, Dublin, Ireland
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16
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AKAP79/150 impacts intrinsic excitability of hippocampal neurons through phospho-regulation of A-type K+ channel trafficking. J Neurosci 2011; 31:1323-32. [PMID: 21273417 DOI: 10.1523/jneurosci.5383-10.2011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Kv4.2, as the primary α-subunit of rapidly inactivating, A-type voltage-gated K(+) (Kv) channels expressed in hippocampal CA1 pyramidal dendrites, plays a critical role in regulating their excitability. Activity-dependent trafficking of Kv4.2 relies on C-terminal protein kinase A (PKA) phosphorylation. A-kinase-anchoring proteins (AKAPs) target PKA to glutamate receptor and ion channel complexes to allow for discrete, local signaling. As part of a previous study, we showed that AKAP79/150 interacts with Kv4.2 complexes and that the two proteins colocalize in hippocampal neurons. However, the nature and functional consequence of their interaction has not been previously explored. Here, we report that the C-terminal domain of Kv4.2 interacts with an internal region of AKAP79/150 that overlaps with its MAGUK (membrane-associated guanylate kinase)-binding domain. We show that AKAP79/150-anchored PKA activity controls Kv4.2 surface expression in heterologous cells and hippocampal neurons. Consistent with these findings, disrupting PKA anchoring led to a decrease in neuronal excitability, while preventing dephosphorylation by the phosphatase calcineurin resulted in increased excitability. These results demonstrate that AKAP79/150 provides a platform for dynamic PKA regulation of Kv4.2 expression, fundamentally impacting CA1 excitability.
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17
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Whyment AD, Coderre E, Wilson JMM, Renaud LP, O'Hare E, Spanswick D. Electrophysiological, pharmacological and molecular profile of the transient outward rectifying conductance in rat sympathetic preganglionic neurons in vitro. Neuroscience 2011; 178:68-81. [PMID: 21211550 DOI: 10.1016/j.neuroscience.2010.12.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 12/27/2010] [Accepted: 12/30/2010] [Indexed: 01/13/2023]
Abstract
Transient outward rectifying conductances or A-like conductances in sympathetic preganglionic neurons (SPN) are prolonged, lasting for hundreds of milliseconds to seconds and are thought to play a key role in the regulation of SPN firing frequency. Here, a multidisciplinary electrophysiological, pharmacological and molecular single-cell rt-PCR approach was used to investigate the kinetics, pharmacological profile and putative K+ channel subunits underlying the transient outward rectifying conductance expressed in SPN. SPN expressed a 4-aminopyridine (4-AP) sensitive transient outward rectification with significantly longer decay kinetics than reported for many other central neurons. The conductance and corresponding current in voltage-clamp conditions was also sensitive to the Kv4.2 and Kv4.3 blocker phrixotoxin-2 (1-10 μM) and the blocker of rapidly inactivating Kv channels, pandinotoxin-Kα (50 nM). The conductance and corresponding current was only weakly sensitive to the Kv1 channel blocker tityustoxin-Kα and insensitive to dendrotoxin I (200 nM) and the Kv3.4 channel blocker BDS-II (1 μM). Single-cell RT-PCR revealed mRNA expression for the α-subunits Kv4.1 and Kv4.3 in the majority and Kv1.5 in less than half of SPN. mRNA for accessory β-subunits was detected for Kvβ2 in all SPN with differential expression of mRNA for KChIP1, Kvβ1 and Kvβ3 and the peptidase homologue DPP6. These data together suggest that the transient outwardly rectifying conductance in SPN is mediated by members of the Kv4 subfamily (Kv4.1 and Kv4.3) in association with the β-subunit Kvβ2. Differential expression of the accessory β subunits, which may act to modulate channel density and kinetics in SPN, may underlie the prolonged and variable time-course of this conductance in these neurons.
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Affiliation(s)
- A D Whyment
- Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
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18
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Kudryashova IV. Structural and functional characteristics of potassium channels and their role in neuroplasticity. NEUROCHEM J+ 2010. [DOI: 10.1134/s1819712410030013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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19
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Blauw HM, Al-Chalabi A, Andersen PM, van Vught PWJ, Diekstra FP, van Es MA, Saris CGJ, Groen EJN, van Rheenen W, Koppers M, Van't Slot R, Strengman E, Estrada K, Rivadeneira F, Hofman A, Uitterlinden AG, Kiemeney LA, Vermeulen SHM, Birve A, Waibel S, Meyer T, Cronin S, McLaughlin RL, Hardiman O, Sapp PC, Tobin MD, Wain LV, Tomik B, Slowik A, Lemmens R, Rujescu D, Schulte C, Gasser T, Brown RH, Landers JE, Robberecht W, Ludolph AC, Ophoff RA, Veldink JH, van den Berg LH. A large genome scan for rare CNVs in amyotrophic lateral sclerosis. Hum Mol Genet 2010; 19:4091-9. [PMID: 20685689 DOI: 10.1093/hmg/ddq323] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease selectively affecting motor neurons in the brain and spinal cord. Recent genome-wide association studies (GWASs) have identified several common variants which increase disease susceptibility. In contrast, rare copy-number variants (CNVs), which have been associated with several neuropsychiatric traits, have not been studied for ALS in well-powered study populations. To examine the role of rare CNVs in ALS susceptibility, we conducted a CNV association study including over 19,000 individuals. In a genome-wide screen of 1875 cases and 8731 controls, we did not find evidence for a difference in global CNV burden between cases and controls. In our association analyses, we identified two loci that met our criteria for follow-up: the DPP6 locus (OR = 3.59, P = 6.6 × 10(-3)), which has already been implicated in ALS pathogenesis, and the 15q11.2 locus, containing NIPA1 (OR = 12.46, P = 9.3 × 10(-5)), the gene causing hereditary spastic paraparesis type 6 (HSP 6). We tested these loci in a replication cohort of 2559 cases and 5887 controls. Again, results were suggestive of association, but did not meet our criteria for independent replication: DPP6 locus: OR = 1.92, P = 0.097, pooled results: OR = 2.64, P = 1.4 × 10(-3); NIPA1: OR = 3.23, P = 0.041, pooled results: OR = 6.20, P = 2.2 × 10(-5)). Our results highlight DPP6 and NIPA1 as candidates for more in-depth studies. Unlike other complex neurological and psychiatric traits, rare CNVs with high effect size do not play a major role in ALS pathogenesis.
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Affiliation(s)
- Hylke M Blauw
- Department of Neurology, Rudolf Magnus Institute of Neuroscience, Genetics, University Medical Centre Utrecht, 3584 CX Utrecht, The Netherlands
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20
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Holton ML, Wang W, Emerson M, Neyses L, Armesilla AL. Plasma membrane calcium ATPase proteins as novel regulators of signal transduction pathways. World J Biol Chem 2010; 1:201-8. [PMID: 21537369 PMCID: PMC3083965 DOI: 10.4331/wjbc.v1.i6.201] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 06/22/2010] [Accepted: 06/24/2010] [Indexed: 02/05/2023] Open
Abstract
Emerging evidence suggests that plasma membrane calcium ATPases (PMCAs) play a key role as regulators of calcium-triggered signal transduction pathways via interaction with partner proteins. PMCAs regulate these pathways by targeting specific proteins to cellular sub-domains where the levels of intracellular free calcium are kept low by the calcium ejection properties of PMCAs. According to this model, PMCAs have been shown to interact functionally with the calcium-sensitive proteins neuronal nitric oxide synthase, calmodulin-dependent serine protein kinase, calcineurin and endothelial nitric oxidase synthase. Transgenic animals with altered expression of PMCAs are being used to evaluate the physiological significance of these interactions. To date, PMCA interactions with calcium-dependent partner proteins have been demonstrated to play a crucial role in the pathophysiology of the cardiovascular system via regulation of the nitric oxide and calcineurin/nuclear factor of activated T cells pathways. This new evidence suggests that PMCAs play a more sophisticated role than the mere ejection of calcium from the cells, by acting as modulators of signaling transduction pathways.
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Affiliation(s)
- Mary Louisa Holton
- Mary Louisa Holton, Angel L Armesilla, Molecular Pharmacology Group, Department of Pharmacy, Research Institute in Healthcare Sciences, Room MA 228, School of Applied sciences, University of Wolverhampton, WV1 1SB, Wolverhampton, United Kingdom
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21
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Moise L, Liu J, Pryazhnikov E, Khiroug L, Jeromin A, Hawrot E. K(V)4.2 channels tagged in the S1-S2 loop for alpha-bungarotoxin binding provide a new tool for studies of channel expression and localization. Channels (Austin) 2010; 4:115-23. [PMID: 20139708 DOI: 10.4161/chan.4.2.10878] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We report the first successful insertion of an engineered, high-affinity alpha-bungarotoxin (Bgtx) binding site into a voltage-gated ion channel, K(V)4.2, using a short, intra-protein embedded sequence (GGWRYYESSLEPYPDGG), derived from a previously described mimotope peptide, HAP. A major benefit to this approach is the ability to live-image the distribution and fate of functional channels on the plasma membrane surface. The Bgtx binding sequence was introduced into the putative extracellular loop between the S1 and S2 transmembrane domains of K(V)4.2. Following co-expression with KChIP3 in tsA201 cells, S1-S2 HAP-tagged channels express at levels comparable to wild-type K(V)4.2, and their activation and inactivation kinetics are minimally altered under most conditions. Binding assays, as well as live staining of surface-expressed K(V)4.2 channels with fluorescent-Bgtx, readily demonstrate specific binding of Bgtx to HAP-tagged K(V)4.2 expressed on the surface of tsA201 cells. Similar live-imaging results were obtained with HAP-tagged K(V)4.2 transfected into hippocampal neurons in primary culture suggesting applicability for future in vivo studies. Furthermore, the activation kinetics of S1-S2-tagged K(V)4.2 channels are minimally affected by the binding of Bgtx, suggesting a limited role if any for the S1-S2 loop in voltage sensing or gating associated conformational changes. Successful functional insertion of the HAP sequence into the S1-S2 linker of K(V)4.2 suggests that other related channels may similarly be amenable to this tagging strategy.
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Affiliation(s)
- Leonard Moise
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI, USA
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22
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Lei Z, Deng P, Li Y, Xu ZC. Downregulation of Kv4.2 channels mediated by NR2B-containing NMDA receptors in cultured hippocampal neurons. Neuroscience 2010; 165:350-62. [PMID: 19857555 DOI: 10.1016/j.neuroscience.2009.10.041] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 10/14/2009] [Accepted: 10/20/2009] [Indexed: 12/29/2022]
Abstract
Somatodendritic Kv4.2 channels mediate transient A-type potassium currents (I(A)), and play critical roles in controlling neuronal excitability and modulating synaptic plasticity. Our studies have shown an NMDA receptor-dependent downregulation of Kv4.2 and I(A). NMDA receptors are heteromeric complexes of NR1 combined with NR2A-NR2D, mainly NR2A and NR2B. Here, we investigate NR2B receptor-mediated modulation of Kv4.2 and I(A) in cultured hippocampal neurons. Application of glutamate caused a reduction in total Kv4.2 protein levels and Kv4.2 clusters, and produced a hyperpolarized shift in the inactivation curve of I(A). The effects of glutamate on Kv4.2 and I(A) were inhibited by pretreatment of NR2B-selective antagonists. NR2B-containing NMDA receptors are believed to be located predominantly extrasynaptically. Like application of glutamate, selective activation of extrasynaptic NMDA receptors caused a reduction in total Kv4.2 protein levels and Kv4.2 clusters, which was also blocked by NR2B-selective antagonists. In contrast, specific stimulation of synaptic NMDA receptors had no effect on Kv4.2. In addition, the influx of Ca(2+) was essential for extrasynaptic modulation of Kv4.2. Calpain inhibitors prevented the reduction of total Kv4.2 protein levels following activation of extrasynaptic NMDA receptors. These results demonstrate that the glutamate-induced downregulation of Kv4.2 and I(A) is mediated by NR2B-containing NMDA receptors and is linked to proteolysis by calpain, which might contribute to the development of neuronal hyperexcitability and neurodegenerative diseases.
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Affiliation(s)
- Z Lei
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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23
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Brittain JM, Piekarz AD, Wang Y, Kondo T, Cummins TR, Khanna R. An atypical role for collapsin response mediator protein 2 (CRMP-2) in neurotransmitter release via interaction with presynaptic voltage-gated calcium channels. J Biol Chem 2009; 284:31375-90. [PMID: 19755421 PMCID: PMC2781534 DOI: 10.1074/jbc.m109.009951] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 08/11/2009] [Indexed: 11/06/2022] Open
Abstract
Collapsin response mediator proteins (CRMPs) specify axon/dendrite fate and axonal growth of neurons through protein-protein interactions. Their functions in presynaptic biology remain unknown. Here, we identify the presynaptic N-type Ca(2+) channel (CaV2.2) as a CRMP-2-interacting protein. CRMP-2 binds directly to CaV2.2 in two regions: the channel domain I-II intracellular loop and the distal C terminus. Both proteins co-localize within presynaptic sites in hippocampal neurons. Overexpression in hippocampal neurons of a CRMP-2 protein fused to enhanced green fluorescent protein caused a significant increase in Ca(2+) channel current density, whereas lentivirus-mediated CRMP-2 knockdown abolished this effect. Interestingly, the increase in Ca(2+) current density was not due to a change in channel gating. Rather, cell surface biotinylation studies showed an increased number of CaV2.2 at the cell surface in CRMP-2-overexpressing neurons. These neurons also exhibited a significant increase in vesicular release in response to a depolarizing stimulus. Depolarization of CRMP-2-enhanced green fluorescent protein-overexpressing neurons elicited a significant increase in release of glutamate compared with control neurons. Toxin block of Ca(2+) entry via CaV2.2 abolished this stimulated release. Thus, the CRMP-2-Ca(2+) channel interaction represents a novel mechanism for modulation of Ca(2+) influx into nerve terminals and, hence, of synaptic strength.
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Affiliation(s)
- Joel M. Brittain
- From the Paul and Carole Stark Neurosciences Research Institute and
| | - Andrew D. Piekarz
- From the Paul and Carole Stark Neurosciences Research Institute and
- Departments of Pharmacology and Toxicologyand
| | - Yuying Wang
- From the Paul and Carole Stark Neurosciences Research Institute and
| | - Takako Kondo
- Otolaryngology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Theodore R. Cummins
- From the Paul and Carole Stark Neurosciences Research Institute and
- Departments of Pharmacology and Toxicologyand
| | - Rajesh Khanna
- From the Paul and Carole Stark Neurosciences Research Institute and
- Departments of Pharmacology and Toxicologyand
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24
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Niwa N, Nerbonne JM. Molecular determinants of cardiac transient outward potassium current (I(to)) expression and regulation. J Mol Cell Cardiol 2009; 48:12-25. [PMID: 19619557 DOI: 10.1016/j.yjmcc.2009.07.013] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 06/25/2009] [Accepted: 07/10/2009] [Indexed: 12/21/2022]
Abstract
Rapidly activating and inactivating cardiac transient outward K(+) currents, I(to), are expressed in most mammalian cardiomyocytes, and contribute importantly to the early phase of action potential repolarization and to plateau potentials. The rapidly recovering (I(t)(o,f)) and slowly recovering (I(t)(o,s)) components are differentially expressed in the myocardium, contributing to regional heterogeneities in action potential waveforms. Consistent with the marked differences in biophysical properties, distinct pore-forming (alpha) subunits underlie the two I(t)(o) components: Kv4.3/Kv4.2 subunits encode I(t)(o,f), whereas Kv1.4 encodes I(t)(o,s), channels. It has also become increasingly clear that cardiac I(t)(o) channels function as components of macromolecular protein complexes, comprising (four) Kvalpha subunits and a variety of accessory subunits and regulatory proteins that influence channel expression, biophysical properties and interactions with the actin cytoskeleton, and contribute to the generation of normal cardiac rhythms. Derangements in the expression or the regulation of I(t)(o) channels in inherited or acquired cardiac diseases would be expected to increase the risk of potentially life-threatening cardiac arrhythmias. Indeed, a recently identified Brugada syndrome mutation in KCNE3 (MiRP2) has been suggested to result in increased I(t)(o,f) densities. Continued focus in this area seems certain to provide new and fundamentally important insights into the molecular determinants of functional I(t)(o) channels and into the molecular mechanisms involved in the dynamic regulation of I(t)(o) channel functioning in the normal and diseased myocardium.
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Affiliation(s)
- Noriko Niwa
- Department of Developmental Biology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8103, St. Louis, MO 63110-1093, USA
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25
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Expression and localization of voltage dependent potassium channel Kv4.2 in epilepsy associated focal lesions. Neurobiol Dis 2009; 36:81-95. [PMID: 19596445 DOI: 10.1016/j.nbd.2009.06.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Revised: 06/08/2009] [Accepted: 06/28/2009] [Indexed: 11/22/2022] Open
Abstract
An increasing number of observations suggest an important role for voltage-gated potassium (Kv) channels in epilepsy. We studied the cell-specific distribution of Kv4.2, phosphorylated (p) Kv4.2 and the Kv4.2 interacting protein NCS-1 using immunocytochemistry in different epilepsy-associated focal lesions. In hippocampal sclerosis (HS), Kv4.2 and pKv4.2 immunoreactivity (IR) was reduced in the neuropil in regions with prominent neuronal cell loss. In both HS and malformations of cortical development (MCD), intense labeling was found in neuronal somata, but not in dendrites. Strong NCS-1 IR was observed in neurons in all lesion types. Western blot analysis demonstrated an increase of total Kv4.2 in all lesions and activation of the ERK pathway in HS and ganglioglioma. These findings indicate that Kv4.2 is expressed in both neuronal and glial cells and its regulation may involve potassium channel interacting proteins, alterations in the subcellular localization of the channel, as well as phosphorylation-mediated posttranslational modifications.
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26
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El-Haou S, Balse E, Neyroud N, Dilanian G, Gavillet B, Abriel H, Coulombe A, Jeromin A, Hatem SN. Kv4 potassium channels form a tripartite complex with the anchoring protein SAP97 and CaMKII in cardiac myocytes. Circ Res 2009; 104:758-69. [PMID: 19213956 DOI: 10.1161/circresaha.108.191007] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Membrane-associated guanylate kinase (MAGUK) proteins are major determinants of the organization of ion channels in the plasma membrane in various cell types. Here, we investigated the interaction between the MAGUK protein SAP97 and cardiac Kv4.2/3 channels, which account for a large part of the outward potassium current, I(to), in heart. We found that the Kv4.2 and Kv4.3 channels C termini interacted with SAP97 via a SAL amino acid sequence. SAP97 and Kv4.3 channels were colocalized in the sarcolemma of cardiomyocytes. In CHO cells, SAP97 clustered Kv4.3 channels in the plasma membrane and increased the current independently of the presence of KChIP and dipeptidyl peptidase-like protein-6. Suppression of SAP97 by using short hairpin RNA inhibited I(to) in cardiac myocytes, whereas its overexpression by using an adenovirus increased I(to). Kv4.3 channels without the SAL sequence were no longer regulated by Ca2+/calmodulin kinase (CaMK)II inhibitors. In cardiac myocytes, pull-down and coimmunoprecipitation assays showed that the Kv4 channel C terminus, SAP97, and CaMKII interact together, an interaction suppressed by SAP97 silencing and enhanced by SAP97 overexpression. In HEK293 cells, SAP97 silencing reproduced the effects of CaMKII inhibition on current kinetics and suppressed Kv4/CaMKII interactions. In conclusion, SAP97 is a major partner for surface expression and CaMKII-dependent regulation of cardiac Kv4 channels.
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Affiliation(s)
- Saïd El-Haou
- UMRS-956, Faculté de Médecine Pierre-Marie Curie, 91 Boulevard de l'Hôpital, 75013 Paris, France
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27
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PSD-95 mediates membrane clustering of the human plasma membrane Ca2+ pump isoform 4b. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1793:1023-32. [PMID: 19073225 DOI: 10.1016/j.bbamcr.2008.11.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 10/31/2008] [Accepted: 11/16/2008] [Indexed: 01/09/2023]
Abstract
Besides the control of global calcium changes, specific plasma membrane calcium ATPase (PMCA) isoforms are involved in the regulation of local calcium signals. Although local calcium signaling requires the confinement of signaling molecules into microdomains, little is known about the specific organization of PMCA molecules within the plasma membrane. Here we show that co-expression with the postsynaptic density-95 (PSD-95) scaffolding protein increased the plasma membrane expression of PMCA4b and redistributed the pump into clusters. The clustering of PMCA4b was fully dependent on the presence of its PDZ-binding sequence. Using the fluorescence recovery after photobleaching (FRAP) technique, we show that the lateral membrane mobility of the clustered PMCA4b is significantly lower than that of the non-clustered molecules. Disruption of the actin-based cytoskeleton by cytochalasin D resulted in increased cluster size. Our results suggest that PSD-95 promotes the formation of high-density PMCA4b microdomains in the plasma membrane and that the membrane cytoskeleton plays an important role in the regulation of this process.
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28
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Vacher H, Mohapatra DP, Trimmer JS. Localization and targeting of voltage-dependent ion channels in mammalian central neurons. Physiol Rev 2008; 88:1407-47. [PMID: 18923186 DOI: 10.1152/physrev.00002.2008] [Citation(s) in RCA: 348] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The intrinsic electrical properties and the synaptic input-output relationships of neurons are governed by the action of voltage-dependent ion channels. The localization of specific populations of ion channels with distinct functional properties at discrete sites in neurons dramatically impacts excitability and synaptic transmission. Molecular cloning studies have revealed a large family of genes encoding voltage-dependent ion channel principal and auxiliary subunits, most of which are expressed in mammalian central neurons. Much recent effort has focused on determining which of these subunits coassemble into native neuronal channel complexes, and the cellular and subcellular distributions of these complexes, as a crucial step in understanding the contribution of these channels to specific aspects of neuronal function. Here we review progress made on recent studies aimed to determine the cellular and subcellular distribution of specific ion channel subunits in mammalian brain neurons using in situ hybridization and immunohistochemistry. We also discuss the repertoire of ion channel subunits in specific neuronal compartments and implications for neuronal physiology. Finally, we discuss the emerging mechanisms for determining the discrete subcellular distributions observed for many neuronal ion channels.
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Affiliation(s)
- Helene Vacher
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, California 95616-8519, USA
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29
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Maffie J, Rudy B. Weighing the evidence for a ternary protein complex mediating A-type K+ currents in neurons. J Physiol 2008; 586:5609-23. [PMID: 18845608 DOI: 10.1113/jphysiol.2008.161620] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The subthreshold-operating A-type K(+) current in neurons (I(SA)) has important roles in the regulation of neuronal excitability, the timing of action potential firing and synaptic integration and plasticity. The channels mediating this current (Kv4 channels) have been implicated in epilepsy, the control of dopamine release, and the regulation of pain plasticity. It has been proposed that Kv4 channels in neurons are ternary complexes of three types of protein: pore forming subunits of the Kv4 subfamily and two types of auxiliary subunits, the Ca(2+) binding proteins KChIPs and the dipeptidyl peptidase-like proteins (DPPLs) DPP6 (also known as DPPX) and DPP10 (4 molecules of each per channel for a total of 12 proteins in the complex). Here we consider the evidence supporting this hypothesis. Kv4 channels in many neurons are likely to be ternary complexes of these three types of protein. KChIPs and DPPLs are required to efficiently traffic Kv4 channels to the plasma membrane and regulate the functional properties of the channels. These proteins may also be important in determining the localization of the channels to specific neuronal compartments, their dynamics, and their response to neuromodulators. A surprisingly large number of additional proteins have been shown to modify Kv4 channels in heterologous expression systems, but their association with native Kv4 channels in neurons has not been properly validated. A critical consideration of the evidence suggests that it is unlikely that association of Kv4 channels with these additional proteins is widespread in the CNS. However, we cannot exclude that some of these proteins may associate with the channels transiently or in specific neurons or neuronal compartments, or that they may associate with the channels in other tissues.
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Affiliation(s)
- Jonathon Maffie
- Smilow Neuroscience Program, Department of Physiology and Neuroscience, New York University School of Medicine, Smilow Research Center, 522 First Avenue, 6th Floor, New York, NY 10016, USA
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30
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McKeown L, Swanton L, Robinson P, Jones OT. Surface expression and distribution of voltage-gated potassium channels in neurons (Review). Mol Membr Biol 2008; 25:332-43. [PMID: 18446619 DOI: 10.1080/09687680801992470] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The last decade has witnessed an exponential increase in interest in one of the great mysteries of nerve cell biology: Specifically, how do neurons know where to place the ion channels that control their excitability? Many of the most important insights have been gleaned from studies on the voltage-gated potassium channels (Kvs) which underlie the shape, duration and frequency of action potentials. In this review, we gather recent evidence on the expression, trafficking and maintenance mechanisms which control the surface density of Kvs in different subcellular compartments of neurons and how these may be regulated to control cell excitability.
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Affiliation(s)
- Lynn McKeown
- Faculty of Life Sciences, The University of Manchester, Manchester, UK
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Lei Z, Deng P, Xu ZC. Regulation of Kv4.2 channels by glutamate in cultured hippocampal neurons. J Neurochem 2008; 106:182-92. [PMID: 18363830 DOI: 10.1111/j.1471-4159.2008.05356.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Somatodendritic voltage-dependent K(+) currents (Kv4.2) channels mediate transient A-type K(+) currents and play critical roles in controlling neuronal excitability. Accumulating evidence has indicated that Kv4.2 channels are key regulatory components of the signaling pathways that lead to synaptic plasticity. In contrast to the extensive studies of glutamate-induced AMPA [(+/-) alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid hydrate] receptors redistribution, less is known about the regulation of Kv4.2 by glutamate. In this study, we report that brief treatment with glutamate rapidly reduced total Kv4.2 levels in cultured hippocampal neurons. The glutamate effect was mimicked by NMDA, but not by AMPA. The effect of glutamate on Kv4.2 was dramatically attenuated by pre-treatment of NMDA receptors antagonist MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine hydrogen maleate] or removal of extracellular Ca(2+). Immunocytochemical analysis showed a loss of Kv4.2 clusters on the neuronal soma and dendrites following glutamate treatment, which was also dependent on the activation of NMDA receptors and the influx of Ca(2+). Furthermore, whole-cell patch-clamp recordings revealed that glutamate caused a hyperpolarized shift in the inactivation curve of A-type K(+) currents, while the activation curve remained unchanged. These results demonstrate a glutamate-induced alteration of Kv4.2 channels in cultured hippocampal neurons, which might be involved in activity-dependent changes of neuronal excitability and synaptic plasticity.
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Affiliation(s)
- Zhigang Lei
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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Abi-Char J, El-Haou S, Balse E, Neyroud N, Vranckx R, Coulombe A, Hatem SN. The anchoring protein SAP97 retains Kv1.5 channels in the plasma membrane of cardiac myocytes. Am J Physiol Heart Circ Physiol 2008; 294:H1851-61. [DOI: 10.1152/ajpheart.01045.2007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Membrane- associated guanylate kinase proteins (MAGUKs) are important determinants of localization and organization of ion channels into specific plasma membrane domains. However, their exact role in channel function and cardiac excitability is not known. We examined the effect of synapse-associated protein 97 (SAP97), a MAGUK abundantly expressed in the heart, on the function and localization of Kv1.5 subunits in cardiac myocytes. Recombinant SAP97 or Kv1.5 subunits tagged with green fluorescent protein (GFP) were overexpressed in rat neonatal cardiac myocytes and in Chinese hamster ovary (CHO) cells from adenoviral or plasmidic vectors. Immunocytochemistry, fluorescence recovery after photobleaching, and patch-clamp techniques were used to study the effects of SAP97 on the localization, mobility, and function of Kv1.5 subunits. Adenovirus-mediated SAP97 overexpression in cardiac myocytes resulted in the clustering of endogenous Kv1.5 subunits at myocyte-myocyte contacts and an increase in both the maintained component of the outward K+current, IKur(5.64 ± 0.57 pA/pF in SAP97 myocytes vs. 3.23 ± 0.43 pA/pF in controls) and the number of 4-aminopyridine-sensitive potassium channels in cell-attached membrane patches. In live myocytes, GFP-Kv1.5 subunits were mobile and organized in clusters at the basal plasma membrane, whereas SAP97 overexpression reduced their mobility. In CHO cells, Kv1.5 channels were diffusely distributed throughout the cell body and freely mobile. When coexpressed with SAP97, Kv subunits were organized in plaquelike clusters and poorly mobile. In conclusion, SAP97 regulates the K+current in cardiac myocytes by retaining and immobilizing Kv1.5 subunits in the plasma membrane. This new regulatory mechanism may contribute to the targeting of Kv channels in cardiac myocytes.
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Kollo M, Holderith N, Antal M, Nusser Z. Unique clustering of A-type potassium channels on different cell types of the main olfactory bulb. Eur J Neurosci 2008; 27:1686-99. [PMID: 18371079 DOI: 10.1111/j.1460-9568.2008.06141.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Theoretical and functional studies predicted a highly non-uniform distribution of voltage-gated ion channels on the neuronal surface. This was confirmed by recent immunolocalization experiments for Na+, Ca2+, hyperpolarization activated mixed cation and K+ channels. These experiments also indicated that some K+ channels were clustered in synaptic or non-synaptic membrane specializations. Here we analysed the subcellular distribution of Kv4.2 and Kv4.3 subunits in the rat main olfactory bulb at high resolution to address whether clustering characterizes their distribution, and whether they are concentrated in synaptic or non-synaptic junctions. The cell surface distribution of the Kv4.2 and Kv4.3 subunits is highly non-uniform. Strong Kv4.2 subunit-immunopositive clusters were detected in intercellular junctions made by mitral, external tufted and granule cells (GCs). We also found Kv4.3 subunit-immunopositive clusters in periglomerular (PGC), deep short-axon and GCs. In the juxtaglomerular region some calretinin-immunopositive glial cells enwrap neighboring PGC somata in a cap-like manner. Kv4.3 subunit clusters are present in the cap membrane that directly contacts the PGC, but not the one that faces the neuropil. In membrane specializations established by members of the same cell type, K+ channels are enriched in both membranes, whereas specializations between different cell types contain a high density of channels asymmetrically. None of the K+ channel-rich junctions showed any of the ultrastructural features of known chemical synapses. Our study provides evidence for highly non-uniform subcellular distributions of A-type K+ channels and predicts their involvements in novel forms of intercellular communication in the olfactory pathway.
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Affiliation(s)
- Mihaly Kollo
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Budapest, Hungary
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Marshall CR, Noor A, Vincent JB, Lionel AC, Feuk L, Skaug J, Shago M, Moessner R, Pinto D, Ren Y, Thiruvahindrapduram B, Fiebig A, Schreiber S, Friedman J, Ketelaars CEJ, Vos YJ, Ficicioglu C, Kirkpatrick S, Nicolson R, Sloman L, Summers A, Gibbons CA, Teebi A, Chitayat D, Weksberg R, Thompson A, Vardy C, Crosbie V, Luscombe S, Baatjes R, Zwaigenbaum L, Roberts W, Fernandez B, Szatmari P, Scherer SW. Structural variation of chromosomes in autism spectrum disorder. Am J Hum Genet 2008; 82:477-88. [PMID: 18252227 DOI: 10.1016/j.ajhg.2007.12.009] [Citation(s) in RCA: 1305] [Impact Index Per Article: 81.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 12/18/2007] [Accepted: 12/19/2007] [Indexed: 02/03/2023] Open
Abstract
Structural variation (copy number variation [CNV] including deletion and duplication, translocation, inversion) of chromosomes has been identified in some individuals with autism spectrum disorder (ASD), but the full etiologic role is unknown. We performed genome-wide assessment for structural abnormalities in 427 unrelated ASD cases via single-nucleotide polymorphism microarrays and karyotyping. With microarrays, we discovered 277 unbalanced CNVs in 44% of ASD families not present in 500 controls (and re-examined in another 1152 controls). Karyotyping detected additional balanced changes. Although most variants were inherited, we found a total of 27 cases with de novo alterations, and in three (11%) of these individuals, two or more new variants were observed. De novo CNVs were found in approximately 7% and approximately 2% of idiopathic families having one child, or two or more ASD siblings, respectively. We also detected 13 loci with recurrent/overlapping CNV in unrelated cases, and at these sites, deletions and duplications affecting the same gene(s) in different individuals and sometimes in asymptomatic carriers were also found. Notwithstanding complexities, our results further implicate the SHANK3-NLGN4-NRXN1 postsynaptic density genes and also identify novel loci at DPP6-DPP10-PCDH9 (synapse complex), ANKRD11, DPYD, PTCHD1, 15q24, among others, for a role in ASD susceptibility. Our most compelling result discovered CNV at 16p11.2 (p = 0.002) (with characteristics of a genomic disorder) at approximately 1% frequency. Some of the ASD regions were also common to mental retardation loci. Structural variants were found in sufficiently high frequency influencing ASD to suggest that cytogenetic and microarray analyses be considered in routine clinical workup.
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Affiliation(s)
- Christian R Marshall
- The Centre for Applied Genomics, The Hospital for Sick Children, Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario M5G 1L7, Canada
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Fenster CP, Fenster SD, Leahy HP, Kurschner C, Blundon JA. Modulation of Kv4.2 K+ currents by neuronal interleukin-16, a PDZ domain-containing protein expressed in the hippocampus and cerebellum. Brain Res 2007; 1162:19-31. [PMID: 17618606 DOI: 10.1016/j.brainres.2007.05.051] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 05/24/2007] [Accepted: 05/24/2007] [Indexed: 11/15/2022]
Abstract
Neuronal interleukin-16 (NIL-16) is a multi-PDZ domain protein expressed in post-mitotic neurons of the hippocampus and cerebellum. NIL-16 contains four PDZ domains, two of which are located within the neuron-specific N-terminal region. In yeast two-hybrid systems, the N-terminus of NIL-16 interacts with several ion channel proteins, including the Kv4.2 subunit of A-type K(+) channels. Here we provide evidence that NIL-16, through interactions with Kv4.2, influences Kv4.2 channel function and subcellular distribution. Specifically, coexpression of NIL-16 with Kv4.2 in COS-7 cells results in a significant reduction in whole-cell A-type current densities; however, when the Kv4.2 PDZ-ligand domain is mutated, Kv4.2 current densities are not affected by NIL-16 coexpression. Moreover, single-channel conductance was not influenced by the presence of NIL-16. In hippocampal neurons, A-type current densities are increased by conditions that inhibit interactions between NIL-16 and Kv4.2, such as overexpression of the Kv4.2 C-terminal PDZ-ligand domain and treatment with small-interfering RNA duplexes that reduce NIL-16 expression. Results of surface biotinylation assays using COS-7 cells suggest that Kv4.2 surface expression levels are reduced by coexpression with NIL-16. In addition, coexpression of NIL-16 with Kv4.2 induces Kv4.2 to form dense intracellular clusters; whereas without NIL-16, Kv4.2 channels cells are dispersed. Taken together, these data suggest that interactions between Kv4.2 and NIL-16 may reduce the number of functional Kv4.2-containing channels on the cell surface. In summary, NIL-16 may provide a novel form of A-type K(+) channel modulation that is localized specifically to neurons of the hippocampus and cerebellum.
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Gardoni F, Mauceri D, Marcello E, Sala C, Di Luca M, Jeromin A. SAP97 directs the localization of Kv4.2 to spines in hippocampal neurons: regulation by CaMKII. J Biol Chem 2007; 282:28691-28699. [PMID: 17635915 DOI: 10.1074/jbc.m701899200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The pore-forming alpha-subunit Kv4.2 is a key constituent of the A-type channel and critically involved in the regulation of dendritic excitability and plasticity. Here we show that Kv4.2 is enriched in the postsynaptic density (PSD) fraction and specifically interacts with synapse-associated protein 97 (SAP97). This interaction requires an intact C terminus of Kv4.2 and occurs via the PDZ domains of SAP97. Pharmacologically induced translocation of SAP97 to spines also drives Kv4.2 to the PSD, whereas SAP97 lentivirally based RNA interference reduces Kv4.2 in the PSD. In addition, calcium/calmodulin-dependent protein kinase II (CaMKII)-dependent SAP97 phosphorylation regulates the subcellular localization of Kv4.2. These results show that SAP97-CaMKII pathway plays an important role for the trafficking of Kv4.2 to dendrites and spines.
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Affiliation(s)
- Fabrizio Gardoni
- Department of Pharmacological Sciences and Center of Excellence on Neurodegenerative Diseases, University of Milan, via Balzaretti 9, 20133 Milan, Italy
| | - Daniela Mauceri
- Department of Pharmacological Sciences and Center of Excellence on Neurodegenerative Diseases, University of Milan, via Balzaretti 9, 20133 Milan, Italy
| | - Elena Marcello
- Department of Pharmacological Sciences and Center of Excellence on Neurodegenerative Diseases, University of Milan, via Balzaretti 9, 20133 Milan, Italy
| | - Carlo Sala
- Cellular and Molecular Pharmacology Section, Institute of Neuroscience, Consiglio Nazionale Ricerche, and Department of Pharmacology, University of Milan, 20129 Milan, Italy
| | - Monica Di Luca
- Department of Pharmacological Sciences and Center of Excellence on Neurodegenerative Diseases, University of Milan, via Balzaretti 9, 20133 Milan, Italy
| | - Andreas Jeromin
- Center for Learning and Memory, University of Texas, Austin, Texas 78712.
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Bedet C, Bruusgaard JC, Vergo S, Groth-Pedersen L, Eimer S, Triller A, Vannier C. Regulation of Gephyrin Assembly and Glycine Receptor Synaptic Stability. J Biol Chem 2006; 281:30046-56. [PMID: 16882665 DOI: 10.1074/jbc.m602155200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gephyrin is required for the formation of clusters of the glycine receptor (GlyR) in the neuronal postsynaptic membrane. It can make trimers and dimers through its N- and C-terminal G and E domains, respectively. Gephyrin oligomerization could thus create a submembrane lattice providing GlyR-binding sites. We investigated the relationships between the stability of cell surface GlyR and the ability of gephyrin splice variants to form oligomers. Using truncated and full-length gephyrins we found that the 13-amino acid sequence (cassette 5) prevents G domain trimerization. Moreover, E domain dimerization is inhibited by the gephyrin central L domain. All of the gephyrin variants bind GlyR beta subunit cytoplasmic loop with high affinity regardless of their cassette composition. Coexpression experiments in COS-7 cells demonstrated that GlyR bound to gephyrin harboring cassette 5 cannot be stabilized at the cell surface. This gephyrin variant was found to deplete synapses from both GlyR and gephyrin in transfected neurons. These data suggest that the relative expression level of cellular variants influence the overall oligomerization pattern of gephyrin and thus the turnover of synaptic GlyR.
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Affiliation(s)
- Cécile Bedet
- INSERM U789, the Laboratoire de Biologie Cellulaire de la Synapse, Ecole Normale Supérieure, F-75005, Paris, France
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Singh B, Ogiwara I, Kaneda M, Tokonami N, Mazaki E, Baba K, Matsuda K, Inoue Y, Yamakawa K. A Kv4.2 truncation mutation in a patient with temporal lobe epilepsy. Neurobiol Dis 2006; 24:245-53. [PMID: 16934482 DOI: 10.1016/j.nbd.2006.07.001] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 06/12/2006] [Accepted: 07/05/2006] [Indexed: 10/24/2022] Open
Abstract
Temporal lobe epilepsy (TLE) has a multifactorial etiology involving developmental, environmental, and genetic components. Here, we report a voltage-gated potassium channel gene mutation found in a TLE patient, namely a Kv4.2 truncation mutation. Kv4.2 channels, encoded by the KCND2 gene, mediate A currents in the brain. The identified mutation corresponds to an N587fsX1 amino acid change, predicted to produce a truncated Kv4.2 protein lacking the last 44 amino acids in the carboxyl terminal. Electrophysiological analysis indicates attenuated K+ current density in cells expressing this Kv4.2-N587fsX1 mutant channel, which is consistent with a model of aberrant neuronal excitability characteristic of TLE. Our observations, together with other lines of evidence, raise the intriguing possibility of a role for KCND2 in the etiology of TLE.
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Affiliation(s)
- Baljinder Singh
- Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama 351-0198, Japan
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Guo W, Jung WE, Marionneau C, Aimond F, Xu H, Yamada KA, Schwarz TL, Demolombe S, Nerbonne JM. Targeted deletion of Kv4.2 eliminates I(to,f) and results in electrical and molecular remodeling, with no evidence of ventricular hypertrophy or myocardial dysfunction. Circ Res 2005; 97:1342-50. [PMID: 16293790 DOI: 10.1161/01.res.0000196559.63223.aa] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous studies have demonstrated a role for voltage-gated K+ (Kv) channel alpha subunits of the Kv4 subfamily in the generation of rapidly inactivating/recovering cardiac transient outward K+ current, I(to,f), channels. Biochemical studies suggest that mouse ventricular I(to,f) channels reflect the heteromeric assembly of Kv4.2 and Kv4.3 with the accessory subunits, KChIP2 and Kvbeta1, and that Kv4.2 is the primary determinant of regional differences in (mouse ventricular) I(to,f) densities. Interestingly, the phenotypic consequences of manipulating I(to,f) expression in different mouse models are distinct. In the experiments here, the effects of the targeted deletion of Kv4.2 (Kv4.2(-/-)) were examined. Unexpectedly, voltage-clamp recordings from Kv4.2(-/-) ventricular myocytes revealed that I(to,f) is eliminated. In addition, the slow transient outward K+ current, I(to,s), and the Kv1.4 protein (which encodes I(to,s)) are upregulated in Kv4.2(-/-) ventricles. Although Kv4.3 mRNA/protein expression is not measurably affected, KChIP2 expression is markedly reduced in Kv4.2(-/-) ventricles. Similar to Kv4.3, expression of Kvbeta1, as well as Kv1.5 and Kv2.1, is similar in wild-type and Kv4.2(-/-) ventricles. In addition, and in marked contrast to previous findings in mice expressing a truncated Kv4.2 transgene, the elimination I(to,f) in Kv4.2(-/-) mice does not result in ventricular hypertrophy. Taken together, these findings demonstrate not only an essential role for Kv4.2 in the generation of mouse ventricular I(to,f) channels but also that the loss of I(to,f) per se does not have overt pathophysiological consequences.
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Affiliation(s)
- Weinong Guo
- Department of Molecular Biology and Pharmacology, Washington University Medical School, St Louis, MO 63110, USA
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Jinno S, Jeromin A, Kosaka T. Postsynaptic and extrasynaptic localization of Kv4.2 channels in the mouse hippocampal region, with special reference to targeted clustering at gabaergic synapses. Neuroscience 2005; 134:483-94. [PMID: 16009497 DOI: 10.1016/j.neuroscience.2005.04.065] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Revised: 04/09/2005] [Accepted: 04/14/2005] [Indexed: 10/25/2022]
Abstract
Voltage-dependent potassium (Kv) channels in the CNS are involved in regulation of subthreshold membrane potentials, and thus reception and integration of synaptic signals. Although such features are particularly important for induction of hippocampal synaptic plasticity, relatively little is known about their subcellular localization. Here we analyzed the detailed distribution of Kv4.2 potassium channels in the mouse hippocampal region using confocal and electron microscopy. At the light microscopic level, the Kv4.2 immunoreactivity occurred in a punctate fashion in the whole area of the hippocampal region. In the hippocampus proper, most of the Kv4.2-positive puncta were small, and they were abundant at the dendritic compartments of pyramidal neurons. High-resolution confocal microscopy revealed that there was no apparent association between Kv4.2-positive puncta with major synaptic markers, such as vesicular glutamate transporters and glutamic acid decarboxylase. In the subicular complex and dentate gyrus, we encountered large distinct Kv4.2-positive puncta at the perimeter of somata and proximal dendrites of principal cells. These puncta were often in contact with glutamic acid decarboxylase-positive boutons, but showed no apparent association with vesicular glutamate transporters. The glutamic acid decarboxylase-positive boutons apposing to Kv4.2-positive puncta were parvalbumin-positive. Quantitative image analysis showed that approximately half of Kv4.2-positive puncta were closely apposed to glutamic acid decarboxylase-positive boutons in the parasubiculum and dentate gyrus. Electron microscopic examination substantiated the presence of large Kv4.2-positive patches at postsynaptic sites of symmetric synapses and small patches at extrasynaptic sites. No presynaptic terminals were labeled. The present findings indicate targeted clustering of Kv4.2 potassium channels at postsynaptic sites of GABAergic synapses and extrasynaptic sites, and provide some key to understand their role in the hippocampal region.
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Affiliation(s)
- S Jinno
- Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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Cubelos B, González-González IM, Giménez C, Zafra F. The scaffolding protein PSD-95 interacts with the glycine transporter GLYT1 and impairs its internalization. J Neurochem 2005; 95:1047-58. [PMID: 16271045 DOI: 10.1111/j.1471-4159.2005.03438.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent evidence indicates that the glycine transporter-1 (GLYT1) plays a role in regulation of NMDA receptor function through tight control of glycine concentration in its surrounding medium. Immunohistochemical studies have demonstrated that, as well as being found in glial cells, GLYT1 is also associated with the pre- and postsynaptic aspects of glutamatergic synapses. In this article, we describe the interaction between GLYT1 and PSD-95 in the rat brain, PSD-95 being a scaffolding protein that participates in the organization of glutamatergic synapses. Mutational analysis reveals that the C-terminal sequence of GLYT1 (-SRI) is necessary for the transporter to interact with the PDZ domains I and II of PSD-95. This C-terminal tripeptide motif also seems to be involved in the trafficking of GLYT1 to the membrane, although this process does not involve PDZ proteins. GLYT1 is able to recruit PSD-95 to the plasma membrane, but it does not affect its clustering. However, the interaction stabilizes this transporter at the plasma membrane, blocking its internalization and producing a significant increase in the V(max) of glycine uptake. We hypothesize that PSD-95 might act as a scaffold for GLYT1 and NMDA receptors, allowing GLYT1 to regulate the concentrations of glycine in the micro-environment of NMDA receptors.
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Affiliation(s)
- Beatriz Cubelos
- Centro de Biología Molecular Severo Ochoa, Facultad de Ciencias, Universidad Autónoma de Madrid, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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Abstract
The heart is a rhythmic electromechanical pump, the functioning of which depends on action potential generation and propagation, followed by relaxation and a period of refractoriness until the next impulse is generated. Myocardial action potentials reflect the sequential activation and inactivation of inward (Na(+) and Ca(2+)) and outward (K(+)) current carrying ion channels. In different regions of the heart, action potential waveforms are distinct, owing to differences in Na(+), Ca(2+), and K(+) channel expression, and these differences contribute to the normal, unidirectional propagation of activity and to the generation of normal cardiac rhythms. Changes in channel functioning, resulting from inherited or acquired disease, affect action potential repolarization and can lead to the generation of life-threatening arrhythmias. There is, therefore, considerable interest in understanding the mechanisms that control cardiac repolarization and rhythm generation. Electrophysiological studies have detailed the properties of the Na(+), Ca(2+), and K(+) currents that generate cardiac action potentials, and molecular cloning has revealed a large number of pore forming (alpha) and accessory (beta, delta, and gamma) subunits thought to contribute to the formation of these channels. Considerable progress has been made in defining the functional roles of the various channels and in identifying the alpha-subunits encoding these channels. Much less is known, however, about the functioning of channel accessory subunits and/or posttranslational processing of the channel proteins. It has also become clear that cardiac ion channels function as components of macromolecular complexes, comprising the alpha-subunits, one or more accessory subunit, and a variety of other regulatory proteins. In addition, these macromolecular channel protein complexes appear to interact with the actin cytoskeleton and/or the extracellular matrix, suggesting important functional links between channel complexes, as well as between cardiac structure and electrical functioning. Important areas of future research will be the identification of (all of) the molecular components of functional cardiac ion channels and delineation of the molecular mechanisms involved in regulating the expression and the functioning of these channels in the normal and the diseased myocardium.
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Affiliation(s)
- Jeanne M Nerbonne
- Dept. of Molecular Biology and Pharmacology, Washington University Medical School, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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Kim J, Wei DS, Hoffman DA. Kv4 potassium channel subunits control action potential repolarization and frequency-dependent broadening in rat hippocampal CA1 pyramidal neurones. J Physiol 2005; 569:41-57. [PMID: 16141270 PMCID: PMC1464206 DOI: 10.1113/jphysiol.2005.095042] [Citation(s) in RCA: 218] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A-type potassium channels regulate neuronal firing frequency and the back-propagation of action potentials (APs) into dendrites of hippocampal CA1 pyramidal neurones. Recent molecular cloning studies have found several families of voltage-gated K(+) channel genes expressed in the mammalian brain. At present, information regarding the relationship between the protein products of these genes and the various neuronal functions performed by voltage-gated K(+) channels is lacking. Here we used a combination of molecular, electrophysiological and imaging techniques to show that one such gene, Kv4.2, controls AP half-width, frequency-dependent AP broadening and dendritic action potential propagation. Using a modified Sindbis virus, we expressed either the enhanced green fluorescence protein (EGFP)-tagged Kv4.2 or an EGFP-tagged dominant negative mutant of Kv4.2 (Kv4.2g(W362F)) in CA1 pyramidal neurones of organotypic slice cultures. Neurones expressing Kv4.2g(W362F) displayed broader action potentials with an increase in frequency-dependent AP broadening during a train compared with control neurones. In addition, Ca(2)(+) imaging of Kv4.2g(W362F) expressing dendrites revealed enhanced AP back-propagation compared to control neurones. Conversely, neurones expressing an increased A-type current through overexpression of Kv4.2 displayed narrower APs with less frequency dependent broadening and decreased dendritic propagation. These results point to Kv4.2 as the major contributor to the A-current in hippocampal CA1 neurones and suggest a prominent role for Kv4.2 in regulating AP shape and dendritic signalling. As Ca(2)(+) influx occurs primarily during AP repolarization, Kv4.2 activity can regulate cellular processes involving Ca(2)(+)-dependent second messenger cascades such as gene expression and synaptic plasticity.
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Affiliation(s)
- Jinhyun Kim
- Molecular Neurophysiology and Biophysics Unit, Laboratory of Synaptic and Cellular Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-3715, USA
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Schofield GG, Ricci A. Electrophysiological characterization of C-terminal Kv4 channel fusion proteins. Pflugers Arch 2005; 450:245-54. [PMID: 15924240 DOI: 10.1007/s00424-005-1405-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 02/25/2005] [Indexed: 01/24/2023]
Affiliation(s)
- Geoffrey G Schofield
- Department of Physiology#SL39, Tulane University Health Sciences Center, New Orleans, LA, 70112, USA.
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Strassle BW, Menegola M, Rhodes KJ, Trimmer JS. Light and electron microscopic analysis of KChIP and Kv4 localization in rat cerebellar granule cells. J Comp Neurol 2005; 484:144-55. [PMID: 15736227 DOI: 10.1002/cne.20443] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Potassium channels are key determinants of neuronal excitability. We recently identified KChIPs as a family of calcium binding proteins that coassociate and colocalize with Kv4 family potassium channels in mammalian brain (An et al. [2000] Nature 403:553). Here, we used light microscopic immunohistochemistry and multilabel immunofluorescence labeling, together with transmission electron microscopic immunohistochemistry, to examine the subcellular distribution of KChIPs and Kv4 channels in adult rat cerebellum. Light microscopic immunohistochemistry was performed on 40-microm free-floating sections using a diaminobenzidine labeling procedure. Multilabel immunofluorescence staining was performed on free-floating sections and on 1-microm ultrathin cryosections. Electron microscopic immunohistochemistry was performed using an immunoperoxidase pre-embedding labeling procedure. By light microscopy, immunoperoxidase labeling showed that Kv4.2, Kv4.3, and KChIPs 1, 3, and 4 (but not KChIP2) were expressed at high levels in cerebellar granule cells (GCs). Kv4.2 and KChIP1 were highly expressed in GCs in rostral cerebellum, whereas Kv4.3 was more highly expressed in GCs in caudal cerebellum. Immunofluorescence labeling revealed that KChIP1 and Kv4.2 are concentrated in somata of cerebellar granule cells and in synaptic glomeruli that surround synaptophysin-positive mossy fiber axon terminals. Electron microscopic analysis revealed that KChIP1 and Kv4.2 immunoreactivity is concentrated along the plasma membrane of cerebellar granule cell somata and dendrites. In synaptic glomeruli, KChIP1 and Kv4.2 immunoreactivity is concentrated along the granule cell dendritic membrane, but is not concentrated at postsynaptic densities. Taken together, these data suggest that A-type potassium channels containing Kv4.2 and KChIP1, and perhaps also KChIP3 and 4, play a critical role in regulating postsynaptic excitability at the cerebellar mossy-fiber/granule cell synapse.
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Affiliation(s)
- Brian W Strassle
- Neuroscience Division, Wyeth Research, Princeton, New Jersey 08543, USA
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46
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Gubitosi-Klug RA, Mancuso DJ, Gross RW. The human Kv1.1 channel is palmitoylated, modulating voltage sensing: Identification of a palmitoylation consensus sequence. Proc Natl Acad Sci U S A 2005; 102:5964-8. [PMID: 15837928 PMCID: PMC1087951 DOI: 10.1073/pnas.0501999102] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Voltage-dependent K(+) channels rely on precise dynamic protein interactions with surrounding plasma membrane lipids to facilitate complex processes such as voltage sensing and channel gating. Many transmembrane-spanning proteins use palmitoylation to facilitate dynamic membrane interactions. Herein, we demonstrate that the human Kv1.1 ion channel is palmitoylated in the cytosolic portion of the S(2)-S(3) linker domain at residue C243. Through heterologous expression of the human Kv1.1 protein in Sf9 cells, covalent radiolabeling with [(3)H]palmitate, chemical stability studies of the [(3)H]-palmitoylated protein, and site-directed mutagenesis, C243 was identified as the predominant site of palmitoylation. The functional sequelae of palmitoylation were examined by analysis of whole cell currents from WT and mutant channels, which identified a 20-mV leftward shift in the current-voltage relationship when palmitoylation at C243 (but not with other cysteine deletions) is prevented by site-directed mutagenesis, implicating a role for palmitoylated C243 in modulating voltage sensing through protein-membrane interactions. Database searches identified an amino acid palmitoylation consensus motif (ACP/RSKT) that is present in multiple other members of the Shaker subfamily of K(+) channels and in several other unrelated regulatory proteins (e.g., CD36, nitric oxide synthase type 2, and the mannose-6 phosphate receptor) that are known to be palmitoylated by thioester linkages at the predicted consensus site cysteine residue. Collectively, these results (i) identify palmitoylation as a mechanism for K(+) channel interactions with plasma membrane lipids contributing to electric field-induced conformational alterations, and ii) define an amino acid consensus sequence for protein palmitoylation.
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Affiliation(s)
- Rose A Gubitosi-Klug
- Division of Bioorganic Chemistry and Molecular Pharmacology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Jerng HH, Pfaffinger PJ, Covarrubias M. Molecular physiology and modulation of somatodendritic A-type potassium channels. Mol Cell Neurosci 2005; 27:343-69. [PMID: 15555915 DOI: 10.1016/j.mcn.2004.06.011] [Citation(s) in RCA: 239] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2004] [Revised: 05/22/2004] [Accepted: 06/08/2004] [Indexed: 11/23/2022] Open
Abstract
The somatodendritic subthreshold A-type K+ current (ISA) in nerve cells is a critical component of the ensemble of voltage-gated ionic currents that determine somatodendritic signal integration. The underlying K+ channel belongs to the Shal subfamily of voltage-gated K+ channels. Most Shal channels across the animal kingdom share a high degree of structural conservation, operate in the subthreshold range of membrane potentials, and exhibit relatively fast inactivation and recovery from inactivation. Mammalian Shal K+ channels (Kv4) undergo preferential closed-state inactivation with features that are generally inconsistent with the classical mechanisms of inactivation typical of Shaker K+ channels. Here, we review (1) the physiological and genetic properties of ISA, 2 the molecular mechanisms of Kv4 inactivation and its remodeling by a family of soluble calcium-binding proteins (KChIPs) and a membrane-bound dipeptidase-like protein (DPPX), and (3) the modulation of Kv4 channels by protein phosphorylation.
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Affiliation(s)
- Henry H Jerng
- Division of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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Misonou H, Trimmer JS. Determinants of voltage-gated potassium channel surface expression and localization in Mammalian neurons. Crit Rev Biochem Mol Biol 2005; 39:125-45. [PMID: 15596548 DOI: 10.1080/10409230490475417] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Neurons strictly regulate expression of a wide variety of voltage-dependent ion channels in their surface membranes to achieve precise yet dynamic control of intrinsic membrane excitability. Neurons also exhibit extreme morphological complexity that underlies diverse aspects of their function. Most ion channels are preferentially targeted to either the axonal or somatodendritic compartments, where they become further localized to discrete membrane subdomains. This restricted accumulation of ion channels enables local control of membrane signaling events in specific microdomains of a given compartment. Voltage-dependent K+ (Kv) channels act as potent modulators of diverse excitatory events such as action potentials, excitatory synaptic potentials, and Ca2+ influx. Kv channels exhibit diverse patterns of cellular expression, and distinct subtype-specific localization, in mammalian central neurons. Here we review the mechanisms regulating the abundance and distribution of Kv channels in mammalian neurons and discuss how dynamic regulation of these events impacts neuronal signaling.
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Affiliation(s)
- Hiroaki Misonou
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, USA
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49
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Aimond F, Kwak SP, Rhodes KJ, Nerbonne JM. Accessory Kvbeta1 subunits differentially modulate the functional expression of voltage-gated K+ channels in mouse ventricular myocytes. Circ Res 2005; 96:451-8. [PMID: 15662035 DOI: 10.1161/01.res.0000156890.25876.63] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Voltage-gated K+ (Kv) channel accessory (beta) subunits associate with pore-forming Kv alpha subunits and modify the properties and/or cell surface expression of Kv channels in heterologous expression systems. There is very little presently known, however, about the functional role(s) of Kv beta subunits in the generation of native cardiac Kv channels. Exploiting mice with a targeted disruption of the Kvbeta1 gene (Kvbeta1-/-), the studies here were undertaken to explore directly the role of Kvbeta1 in the generation of ventricular Kv currents. Action potential waveforms and peak Kv current densities are indistinguishable in myocytes isolated from the left ventricular apex (LVA) of Kvbeta1-/- and wild-type (WT) animals. Analysis of Kv current waveforms, however, revealed that mean+/-SEM I(to,f) density is significantly (P< or =0.01) lower in Kvbeta1-/- (21.0+/-0.9 pA/pF; n=68), than in WT (25.3+/-1.4 pA/pF; n=42), LVA myocytes, and that mean+/-SEM I(K,slow) density is significantly (P< or =0.01) higher in Kvbeta1-/- (19.1+/-0.9 pA/pF; n=68), compared with WT (15.9+/-0.7 pA/pF; n=42), LVA cells. Pharmacological studies demonstrated that the TEA-sensitive component of I(K,slow), I(K,slow2,) is selectively increased in Kvbeta1-/- LVA myocytes. In parallel with the alterations in I(to,f) and I(K,slow2) densities, Kv4.3 expression is decreased and Kv2.1 expression is increased in Kvbeta1-/- ventricles. Taken together, these results demonstrate that Kvbeta1 differentially regulates the functional cell surface expression of myocardial I(to,f) and I(K,slow2) channels.
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MESH Headings
- Action Potentials
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Base Sequence
- Calcium-Binding Proteins/metabolism
- Cell Membrane/metabolism
- Exons
- Heart Ventricles/cytology
- Heart Ventricles/metabolism
- Introns
- Ion Channel Gating/drug effects
- Kv Channel-Interacting Proteins
- Kv1.1 Potassium Channel
- Kv1.2 Potassium Channel
- Kv1.4 Potassium Channel
- Kv1.5 Potassium Channel
- Large-Conductance Calcium-Activated Potassium Channels
- Membrane Proteins/metabolism
- Mice
- Mice, Knockout
- Molecular Sequence Data
- Myocardium/metabolism
- Myocytes, Cardiac/metabolism
- Patch-Clamp Techniques
- Potassium/metabolism
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/biosynthesis
- Potassium Channels, Calcium-Activated/chemistry
- Potassium Channels, Calcium-Activated/deficiency
- Potassium Channels, Calcium-Activated/genetics
- Potassium Channels, Calcium-Activated/physiology
- Potassium Channels, Voltage-Gated/biosynthesis
- Potassium Channels, Voltage-Gated/chemistry
- Potassium Channels, Voltage-Gated/drug effects
- Potassium Channels, Voltage-Gated/genetics
- Potassium Channels, Voltage-Gated/metabolism
- Potassium Channels, Voltage-Gated/physiology
- Protein Interaction Mapping
- Protein Subunits
- Sequence Alignment
- Shab Potassium Channels
- Shal Potassium Channels
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Affiliation(s)
- Franck Aimond
- Department of Molecular Biology and Pharmacology, Washington University Medical School, St Louis, MO 63110-1093, USA
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50
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Brooke RE, Atkinson L, Batten TFC, Deuchars SA, Deuchars J. Association of potassium channel Kv3.4 subunits with pre- and post-synaptic structures in brainstem and spinal cord. Neuroscience 2004; 126:1001-10. [PMID: 15207333 DOI: 10.1016/j.neuroscience.2004.03.051] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2004] [Indexed: 11/22/2022]
Abstract
Voltage-gated K+ channels (Kv) are divided into eight subfamilies (Kv1-8) and play a major role in determining the excitability of neurones. Members of the Kv3 subfamily are highly abundant in the CNS, with each Kv3 gene (Kv3.1-Kv3.4) exhibiting a unique pattern of expression, although single neurones can express more than one subtype. Of the Kv3 subunits relatively little is known of the Kv3.4 subunit distribution in the nervous system, particularly in the brainstem and spinal cord of the rat. We performed immunohistochemistry to determine both the cellular and sub-cellular distribution of the Kv3.4 subunit in these areas. Kv3.4 subunit immunoreactivity (Kv3.4-IR) was widespread, with dense, punctate staining in many regions including the intermediolateral cell column (IML) and the dorsal vagal nucleus (DVN), nucleus ambiguus (NA) and nucleus tractus solitarius (NTS). In the ventral horn a presynaptic location was confirmed by co-localization of Kv3.4-IR with the synaptic vesicle protein, SV2 and also with the glutamate vesicle markers vesicular glutamate transporter (VGluT) 1, VGluT2 or the glycine transporter GlyT2, suggesting a role for the channel in both excitatory and inhibitory neurotransmission. Electron microscopy confirmed a presynaptic terminal location of Kv3.4-IR in the VH, IML, DVN, NA and NTS. Interestingly however, patches of Kv3.4-IR were also revealed postsynaptically in dendritic and somatic structures throughout these areas. This staining was striking due to its localization at synaptic junctions at terminals with morphological features consistent with excitatory functions, suggesting an association with the postsynaptic density. Therefore the pre and postsynaptic localization of Kv3.4-IR suggests a role both in the control of transmitter release and in regulating neuronal excitability.
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Affiliation(s)
- R E Brooke
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9NQ, UK
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