51
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Tang S, Wang T, Zhang X, Guo Y, Xu P, Zeng J, Luo Z, Li D, Zheng Y, Luo Y, Yu C, Xu Z. Olfactomedin-3 Enhances Seizure Activity by Interacting With AMPA Receptors in Epilepsy Models. Front Cell Dev Biol 2020; 8:722. [PMID: 32850838 PMCID: PMC7431667 DOI: 10.3389/fcell.2020.00722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/14/2020] [Indexed: 11/22/2022] Open
Abstract
Background: OLFM3 (olfactomedin-3) is a member of the olfactomedin domain family, which has been found to stimulate the formation and adhesion of tight cell connections and to regulate cytoskeleton formation and cell migration. Differences in the gene coding for OLFM3 have been found between patients with epilepsy and controls. However, the exact role of OLFM3 in epilepsy has not been thoroughly investigated. Methods: Biochemical methods were used to assess OLFM3 expression and localization in the cortex of patients with temporal lobe epilepsy and in the hippocampus and cortex of epileptic mice. Electrophysiological recordings were used to measure the role of OLFM3 in regulating hippocampal excitability in a model of magnesium-free-induced seizure in vitro. Behavioral experiments were performed in a pentylenetetrazol (PTZ)-induced seizure model, and electroencephalograms (EEGs) were recorded in the chronic phase of the kainic acid (KA)-induced epilepsy model in vivo. OLFM3 and its interaction with AMPAR (α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor) subunits were analyzed by co-immunoprecipitation. Results: The expression of OLFM3 was increased in the cortex of patients with temporal lobe epilepsy and in the hippocampus and cortex of epileptic mice compared with controls. Interestingly, lentivirus-mediated overexpression of OLFM3 in the hippocampus increased the susceptibility of mice to PTZ-induced seizures, and OLFM3 knockdown had the opposite effect. OLFM3 affected AMPAR currents in a brain-slice model of epileptiform activity induced by Mg2+-free medium. We found that OLFM3 co-immunoprecipitation with GluA1 and GluA2. Furthermore, downregulation or overexpression of OLFM3 in the hippocampus affected the membrane expression of GluA1 and GluA2 in epileptic mice. Conclusion: These findings reveal that OLFM3 may enhance seizure activity by interacting with GluA1 and GluA2, potentially indicating a molecular mechanism for new therapeutic strategies.
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Affiliation(s)
- Shirong Tang
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Department of Neurology, The Thirteenth People's Hospital of Chongqing, Chongqing, China
| | - Tiancheng Wang
- Department of Neurology, Lanzhou University Second Hospital, Lanzhou, China
| | - Xiaogang Zhang
- Department of Neurology, Chongqing General Hospital, University of Chinese Academy of Sciences, Chongqing, China
| | - Yi Guo
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ping Xu
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Junwei Zeng
- Department of Physiology, Zunyi Medical University, Zunyi, China
| | - Zhong Luo
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Dongxu Li
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Yongsu Zheng
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Yuemei Luo
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Changyin Yu
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Zucai Xu
- Department of Neurology, The Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Key Laboratory of Brain Science, Zunyi Medical University, Zunyi, China
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52
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Jacobi E, Engelhardt J. Modulation of information processing by AMPA receptor auxiliary subunits. J Physiol 2020; 599:471-483. [DOI: 10.1113/jp276698] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/25/2020] [Indexed: 12/13/2022] Open
Affiliation(s)
- Eric Jacobi
- Institute of Pathophysiology University Medical Center of the Johannes Gutenberg University Mainz Mainz Germany
- Focus Program Translational Neurosciences (FTN) University Medical Center of the Johannes Gutenberg‐University Mainz Mainz Germany
| | - Jakob Engelhardt
- Institute of Pathophysiology University Medical Center of the Johannes Gutenberg University Mainz Mainz Germany
- Focus Program Translational Neurosciences (FTN) University Medical Center of the Johannes Gutenberg‐University Mainz Mainz Germany
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53
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Murtaza N, Uy J, Singh KK. Emerging proteomic approaches to identify the underlying pathophysiology of neurodevelopmental and neurodegenerative disorders. Mol Autism 2020; 11:27. [PMID: 32317014 PMCID: PMC7171839 DOI: 10.1186/s13229-020-00334-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 04/06/2020] [Indexed: 12/18/2022] Open
Abstract
Proteomics is the large-scale study of the total protein content and their overall function within a cell through multiple facets of research. Advancements in proteomic methods have moved past the simple quantification of proteins to the identification of post-translational modifications (PTMs) and the ability to probe interactions between these proteins, spatially and temporally. Increased sensitivity and resolution of mass spectrometers and sample preparation protocols have drastically reduced the large amount of cells required and the experimental variability that had previously hindered its use in studying human neurological disorders. Proteomics offers a new perspective to study the altered molecular pathways and networks that are associated with autism spectrum disorders (ASD). The differences between the transcriptome and proteome, combined with the various types of post-translation modifications that regulate protein function and localization, highlight a novel level of research that has not been appropriately investigated. In this review, we will discuss strategies using proteomics to study ASD and other neurological disorders, with a focus on how these approaches can be combined with induced pluripotent stem cell (iPSC) studies. Proteomic analysis of iPSC-derived neurons have already been used to measure changes in the proteome caused by patient mutations, analyze changes in PTMs that resulted in altered biological pathways, and identify potential biomarkers. Further advancements in both proteomic techniques and human iPSC differentiation protocols will continue to push the field towards better understanding ASD disease pathophysiology. Proteomics using iPSC-derived neurons from individuals with ASD offers a window for observing the altered proteome, which is necessary in the future development of therapeutics against specific targets.
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Affiliation(s)
- Nadeem Murtaza
- Stem Cell and Cancer Research Institute, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8N 3Z5, Canada
| | - Jarryll Uy
- Stem Cell and Cancer Research Institute, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8N 3Z5, Canada
| | - Karun K Singh
- Stem Cell and Cancer Research Institute, Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, L8N 3Z5, Canada.
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54
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Willems J, de Jong APH, Scheefhals N, Mertens E, Catsburg LAE, Poorthuis RB, de Winter F, Verhaagen J, Meye FJ, MacGillavry HD. ORANGE: A CRISPR/Cas9-based genome editing toolbox for epitope tagging of endogenous proteins in neurons. PLoS Biol 2020; 18:e3000665. [PMID: 32275651 PMCID: PMC7176289 DOI: 10.1371/journal.pbio.3000665] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 04/22/2020] [Accepted: 03/27/2020] [Indexed: 12/15/2022] Open
Abstract
The correct subcellular distribution of proteins establishes the complex morphology and function of neurons. Fluorescence microscopy techniques are invaluable to investigate subcellular protein distribution, but they suffer from the limited ability to efficiently and reliably label endogenous proteins with fluorescent probes. We developed ORANGE: Open Resource for the Application of Neuronal Genome Editing, which mediates targeted genomic integration of epitope tags in rodent dissociated neuronal culture, in organotypic slices, and in vivo. ORANGE includes a knock-in library for in-depth investigation of endogenous protein distribution, viral vectors, and a detailed two-step cloning protocol to develop knock-ins for novel targets. Using ORANGE with (live-cell) superresolution microscopy, we revealed the dynamic nanoscale organization of endogenous neurotransmitter receptors and synaptic scaffolding proteins, as well as previously uncharacterized proteins. Finally, we developed a mechanism to create multiple knock-ins in neurons, mediating multiplex imaging of endogenous proteins. Thus, ORANGE enables quantification of expression, distribution, and dynamics for virtually any protein in neurons at nanoscale resolution. This study describes the development of a genome editing toolbox (ORANGE) for endogenous tagging of proteins in neurons. This open resource allows the investigation of protein localization and dynamics in neurons using live-cell and super-resolution imaging techniques.
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Affiliation(s)
- Jelmer Willems
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Arthur P. H. de Jong
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Nicky Scheefhals
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Eline Mertens
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Lisa A. E. Catsburg
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | - Rogier B. Poorthuis
- Department of Translational Neuroscience, UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands
| | - Fred de Winter
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, the Netherlands
| | - Joost Verhaagen
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, the Netherlands
| | - Frank J. Meye
- Department of Translational Neuroscience, UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands
| | - Harold D. MacGillavry
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, the Netherlands
- * E-mail:
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55
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Kamalova A, Nakagawa T. AMPA receptor structure and auxiliary subunits. J Physiol 2020; 599:453-469. [PMID: 32004381 DOI: 10.1113/jp278701] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/28/2020] [Indexed: 11/08/2022] Open
Abstract
Fast excitatory synaptic transmission in the mammalian brain is largely mediated by AMPA-type ionotropic glutamate receptors (AMPARs), which are activated by the neurotransmitter glutamate. In synapses, the function of AMPARs is tuned by their auxiliary subunits, a diverse set of membrane proteins associated with the core pore-forming subunits of the AMPARs. Each auxiliary subunit provides distinct functional modulation of AMPARs, ranging from regulation of trafficking to shaping ion channel gating kinetics. Understanding the molecular mechanism of the function of these complexes is key to decoding synaptic modulation and their global roles in cognitive activities, such as learning and memory. Here, we review the structural and molecular complexity of AMPAR-auxiliary subunit complexes, as well as their functional diversity in different brain regions. We suggest that the recent structural information provides new insights into the molecular mechanisms underlying synaptic functions of AMPAR-auxiliary subunit complexes.
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Affiliation(s)
- Aichurok Kamalova
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Center for Structural Biology, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
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56
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Nakagawa T. Structures of the AMPA receptor in complex with its auxiliary subunit cornichon. Science 2019; 366:1259-1263. [DOI: 10.1126/science.aay2783] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 10/21/2019] [Indexed: 01/18/2023]
Abstract
In the brain, AMPA-type glutamate receptors (AMPARs) form complexes with their auxiliary subunits and mediate the majority of fast excitatory neurotransmission. Signals transduced by these complexes are critical for synaptic plasticity, learning, and memory. The two major categories of AMPAR auxiliary subunits are transmembrane AMPAR regulatory proteins (TARPs) and cornichon homologs (CNIHs); these subunits share little homology and play distinct roles in controlling ion channel gating and trafficking of AMPAR. Here, I report high-resolution cryo–electron microscopy structures of AMPAR in complex with CNIH3. Contrary to its predicted membrane topology, CNIH3 lacks an extracellular domain and instead contains four membrane-spanning helices. The protein-protein interaction interface that dictates channel modulation and the lipids surrounding the complex are revealed. These structures provide insights into the molecular mechanism for ion channel modulation and assembly of AMPAR/CNIH3 complexes.
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Affiliation(s)
- Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Center for Structural Biology, and Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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57
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Pronker MF, van den Hoek H, Janssen BJC. Design and structural characterisation of olfactomedin-1 variants as tools for functional studies. BMC Mol Cell Biol 2019; 20:50. [PMID: 31726976 PMCID: PMC6857237 DOI: 10.1186/s12860-019-0232-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 10/10/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Olfactomedin-1 (Olfm1; also known as Noelin or Pancortin) is a highly-expressed secreted brain and retina protein and its four isoforms have different roles in nervous system development and function. Structural studies showed that the long Olfm1 isoform BMZ forms a disulfide-linked tetramer with a V-shaped architecture. The tips of the Olfm1 "V" each consist of two C-terminal β-propeller domains that enclose a calcium binding site. Functional characterisation of Olfm1 may be aided by new biochemical tools derived from these core structural elements. RESULTS Here we present the production, purification and structural analysis of three novel monomeric, dimeric and tetrameric forms of mammalian Olfm1 for functional studies. We characterise these constructs structurally by high-resolution X-ray crystallography and small-angle X-ray scattering. The crystal structure of the Olfm1 β-propeller domain (to 1.25 Å) represents the highest-resolution structure of an olfactomedin family member to date, revealing features such as a hydrophilic tunnel containing water molecules running into the core of the domain where the calcium binding site resides. The shorter Olfactomedin-1 isoform BMY is a disulfide-linked tetramer with a shape similar to the corresponding region in the longer BMZ isoform. CONCLUSIONS These recombinantly-expressed protein tools should assist future studies, for example of biophysical, electrophysiological or morphological nature, to help elucidate the functions of Olfm1 in the mature mammalian brain. The control over the oligomeric state of Olfm1 provides a firm basis to better understand the role of Olfm1 in the (trans-synaptic) tethering or avidity-mediated clustering of synaptic receptors such as post-synaptic AMPA receptors and pre-synaptic amyloid precursor protein. In addition, the variation in domain composition of these protein tools provides a means to dissect the Olfm1 regions important for receptor binding.
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Affiliation(s)
- Matti F Pronker
- MRC Laboratory of Molecular Biology, Division of Neurobiology, Francis Crick Avenue, Cambridge, CB2 0QH, UK. .,Bijvoet Center for Biomolecular Research, Utrecht University, Crystal and Structural Chemistry, Kruytgebouw, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
| | - Hugo van den Hoek
- Bijvoet Center for Biomolecular Research, Utrecht University, Crystal and Structural Chemistry, Kruytgebouw, Padualaan 8, 3584 CH, Utrecht, The Netherlands.,Department of Molecular Structural Biology, Max Planck institute for Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Bert J C Janssen
- Bijvoet Center for Biomolecular Research, Utrecht University, Crystal and Structural Chemistry, Kruytgebouw, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
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58
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Twomey EC, Yelshanskaya MV, Sobolevsky AI. Structural and functional insights into transmembrane AMPA receptor regulatory protein complexes. J Gen Physiol 2019; 151:1347-1356. [PMID: 31615831 PMCID: PMC6888759 DOI: 10.1085/jgp.201812264] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 09/26/2019] [Indexed: 11/20/2022] Open
Abstract
Twomey et al. examine recent structural and functional data that have provided insight into AMPA receptor modulation by TARPs. Fast excitatory neurotransmission is mediated by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype of ionotropic glutamate receptor (AMPAR). AMPARs initiate depolarization of the postsynaptic neuron by allowing cations to enter through their ion channel pores in response to binding of the neurotransmitter glutamate. AMPAR function is dramatically affected by auxiliary subunits, which are regulatory proteins that form various complexes with AMPARs throughout the brain. The most well-studied auxiliary subunits are the transmembrane AMPAR regulatory proteins (TARPs), which alter the assembly, trafficking, localization, kinetics, and pharmacology of AMPARs. Recent structural and functional studies of TARPs and the TARP-fold germ cell-specific gene 1-like (GSG1L) subunit have provided important glimpses into how auxiliary subunits regulate the function of synaptic complexes. In this review, we put these recent structures in the context of new functional findings in order to gain insight into the determinants of AMPAR regulation by TARPs. We thus reveal why TARPs display a broad range of effects despite their conserved modular architecture.
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Affiliation(s)
- Edward C Twomey
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY
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59
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Coombs ID, Soto D, McGee TP, Gold MG, Farrant M, Cull-Candy SG. Homomeric GluA2(R) AMPA receptors can conduct when desensitized. Nat Commun 2019; 10:4312. [PMID: 31541113 PMCID: PMC6754398 DOI: 10.1038/s41467-019-12280-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/28/2019] [Indexed: 11/21/2022] Open
Abstract
Desensitization is a canonical property of ligand-gated ion channels, causing progressive current decline in the continued presence of agonist. AMPA-type glutamate receptors (AMPARs), which mediate fast excitatory signaling throughout the brain, exhibit profound desensitization. Recent cryo-EM studies of AMPAR assemblies show their ion channels to be closed in the desensitized state. Here we present evidence that homomeric Q/R-edited AMPARs still allow ions to flow when the receptors are desensitized. GluA2(R) expressed alone, or with auxiliary subunits (γ-2, γ-8 or GSG1L), generates large fractional steady-state currents and anomalous current-variance relationships. Our results from fluctuation analysis, single-channel recording, and kinetic modeling, suggest that the steady-state current is mediated predominantly by conducting desensitized receptors. When combined with crystallography this unique functional readout of a hitherto silent state enabled us to examine cross-linked cysteine mutants to probe the conformation of the desensitized ligand binding domain of functioning AMPAR complexes. AMPA-type glutamate receptors, which mediate fast excitatory signaling throughout the brain, exhibit profound desensitization, causing a progressive current decline in the continued presence of agonist. Here authors show that homomeric Q/R edited AMPARs still allow ions to flow when the receptors are desensitized.
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Affiliation(s)
- Ian D Coombs
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - David Soto
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.,Department of Biomedicine, Neurophysiology Laboratory, Medical School, Institute of Neurosciences, University of Barcelona, Casanova 143, 08036, Barcelona, Spain
| | - Thomas P McGee
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Matthew G Gold
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Mark Farrant
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
| | - Stuart G Cull-Candy
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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60
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Troyano-Rodriguez E, Mann S, Ullah R, Ahmad M. PRRT1 regulates basal and plasticity-induced AMPA receptor trafficking. Mol Cell Neurosci 2019; 98:155-163. [PMID: 31216424 DOI: 10.1016/j.mcn.2019.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 06/07/2019] [Accepted: 06/13/2019] [Indexed: 01/20/2023] Open
Abstract
AMPA-type glutamate receptors (AMPAR) are one of the principal mediators of fast excitatory synaptic transmission in the brain. These receptors associate with multiple integral membrane proteins which influence their trafficking and channel properties. Proline-rich transmembrane protein 1 (PRRT1) is a membrane protein and an understudied component of native AMPAR complexes. In order to understand the regulation of AMPARs by PRRT1, we have performed electrophysiological and biochemical investigations on acute hippocampal slices derived from PRRT1 knockout mice. Our results show that PRRT1 controls the levels of AMPARs at the cell surface, though it is dispensable for synaptic transmission. PRRT1 has differential effects on the stability of AMPAR GluA1 subunit phosphorylated at S845 and at S831, two residues at which the phosphorylation status has major influences on receptor trafficking. Furthermore, PRRT1 is required for NMDA receptor-dependent long-term depression (LTD) and proper NMDA-induced AMPAR trafficking. These findings position PRRT1 as an important regulator of AMPAR stabilization and trafficking in different subcellular pools under basal conditions and during synaptic plasticity.
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Affiliation(s)
- Eva Troyano-Rodriguez
- Department of Cell Biology and Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Shivani Mann
- Department of Cell Biology and Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Raja Ullah
- Department of Cell Biology and Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Mohiuddin Ahmad
- Department of Cell Biology and Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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61
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Structural biology of glutamate receptor ion channels: towards an understanding of mechanism. Curr Opin Struct Biol 2019; 57:185-195. [PMID: 31185364 DOI: 10.1016/j.sbi.2019.05.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 12/21/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric ion channels that mediate signal transmission at neuronal synapses, where they contribute centrally to the postsynaptic plasticity that underlies learning and memory. Receptor activation by l-glutamate triggers complex allosteric cascades that are transmitted through the layered and highly flexible receptor assembly culminating in opening a cation-selective pore. This process is shaped by the arrangement of the four core subunits as well as the presence of various auxiliary subunits, and is subject to regulation by an array of small molecule modulators targeting a number of sites throughout the complex. Here, we discuss recent structures of iGluR homomers and heteromers illuminating the organization and subunit arrangement of the core tetramer, co-assembled with auxiliary subunits and in complex with allosteric modulators.
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62
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Bissen D, Foss F, Acker-Palmer A. AMPA receptors and their minions: auxiliary proteins in AMPA receptor trafficking. Cell Mol Life Sci 2019; 76:2133-2169. [PMID: 30937469 PMCID: PMC6502786 DOI: 10.1007/s00018-019-03068-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/12/2019] [Accepted: 03/07/2019] [Indexed: 12/12/2022]
Abstract
To correctly transfer information, neuronal networks need to continuously adjust their synaptic strength to extrinsic stimuli. This ability, termed synaptic plasticity, is at the heart of their function and is, thus, tightly regulated. In glutamatergic neurons, synaptic strength is controlled by the number and function of AMPA receptors at the postsynapse, which mediate most of the fast excitatory transmission in the central nervous system. Their trafficking to, at, and from the synapse, is, therefore, a key mechanism underlying synaptic plasticity. Intensive research over the last 20 years has revealed the increasing importance of interacting proteins, which accompany AMPA receptors throughout their lifetime and help to refine the temporal and spatial modulation of their trafficking and function. In this review, we discuss the current knowledge about the roles of key partners in regulating AMPA receptor trafficking and focus especially on the movement between the intracellular, extrasynaptic, and synaptic pools. We examine their involvement not only in basal synaptic function, but also in Hebbian and homeostatic plasticity. Included in our review are well-established AMPA receptor interactants such as GRIP1 and PICK1, the classical auxiliary subunits TARP and CNIH, and the newest additions to AMPA receptor native complexes.
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Affiliation(s)
- Diane Bissen
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
- Max Planck Institute for Brain Research, Max von Laue Str. 4, 60438, Frankfurt am Main, Germany
| | - Franziska Foss
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
| | - Amparo Acker-Palmer
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.
- Max Planck Institute for Brain Research, Max von Laue Str. 4, 60438, Frankfurt am Main, Germany.
- Cardio-Pulmonary Institute (CPI), Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.
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63
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AMPA Receptor Auxiliary Proteins of the CKAMP Family. Int J Mol Sci 2019; 20:ijms20061460. [PMID: 30909450 PMCID: PMC6470934 DOI: 10.3390/ijms20061460] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/12/2019] [Accepted: 03/14/2019] [Indexed: 12/26/2022] Open
Abstract
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are assembled of four core subunits and several additional interacting proteins. Cystine-knot AMPA receptor-modulating proteins (CKAMPs) constitute a family of four proteins that influence the trafficking, subcellular localization and function of AMPA receptors. The four CKAMP family members CKAMP39/shisa8, CKAMP44/shisa9, CKAMP52/shisa6 and CKAMP59/shisa7 differ in their expression profile and their modulatory influence on AMPA receptor function. In this review, I report about recent findings on the differential roles of CKAMP family members.
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64
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Structure and mechanism of AMPA receptor - auxiliary protein complexes. Curr Opin Struct Biol 2019; 54:104-111. [PMID: 30825796 DOI: 10.1016/j.sbi.2019.01.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 01/25/2019] [Accepted: 01/28/2019] [Indexed: 11/21/2022]
Abstract
Ionotropic glutamate receptors in vertebrates are composed of three major subtypes - AMPA, kainate, and NMDA receptors - and mediate the majority of fast excitatory neurotransmission at chemical synapses of the central nervous system. Among the three major families, native AMPA receptors function as complexes with a variety of auxiliary subunits, which in turn modulate receptor trafficking, gating, pharmacology, and permeation. Despite the long history of structure-mechanism studies using soluble receptor domains or intact yet isolated receptors, structures of AMPA receptor-auxiliary subunit complexes have not been available until recent breakthroughs in single-particle cryo-electron microscopy. Single particle cryo-EM studies have, in turn, provided new insights into the structure and organization of AMPA receptor - auxiliary protein complexes and into the molecular mechanisms of AMPA receptor activation and desensitization.
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65
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Mölders A, Koch A, Menke R, Klöcker N. Heterogeneity of the astrocytic AMPA-receptor transcriptome. Glia 2018; 66:2604-2616. [PMID: 30370555 DOI: 10.1002/glia.23514] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 07/01/2018] [Accepted: 07/18/2018] [Indexed: 11/06/2022]
Abstract
Astrocytes form the largest class of glial cells in the central nervous system. They serve plenty of diverse functions that range from supporting the formation and proper operation of synapses to controlling the blood-brain barrier. For many of them, the expression of ionotropic glutamate receptors of the AMPA subtype (AMPARs) in astrocytes is of key importance. AMPARs form as macromolecular protein complexes, whose composition of the pore-lining GluA subunits and of an extensive set of core and peripheral complex constituents defines both their trafficking and gating behavior. Although astrocytic AMPARs have been reported to exhibit heterogeneous properties, their molecular composition is largely unknown. In this study, we sought to quantify the astrocytic AMPAR transcriptome during brain development and with respect to selected brain regions. Whereas the early postnatal pattern of AMPAR mRNA expression showed minor variation over time, it did show significant heterogeneity in different brain regions. Cerebellar astrocytes express a combination of AMPAR complex constituents that is remarkably distinct from the one in neocortical or hippocampal astrocytes. Our study provides a workflow and a first reference for future investigations into the molecular and functional diversity of glial AMPARs.
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Affiliation(s)
- Andrea Mölders
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Angela Koch
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Raphael Menke
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
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66
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Bowie D. Polyamine-mediated channel block of ionotropic glutamate receptors and its regulation by auxiliary proteins. J Biol Chem 2018; 293:18789-18802. [PMID: 30333231 DOI: 10.1074/jbc.tm118.003794] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Most excitatory neurotransmission in the mammalian brain is mediated by a family of plasma membrane-bound signaling proteins called ionotropic glutamate receptors (iGluRs). iGluRs assemble at central synapses as tetramers, forming a central ion-channel pore whose primary function is to rapidly transport Na+ and Ca2+ in response to binding the neurotransmitter l-glutamic acid. The pore of iGluRs is also accessible to bulkier cytoplasmic cations, such as the polyamines spermine, spermidine, and putrescine, which are drawn into the permeation pathway, but get stuck and block the movement of other ions. The degree of this polyamine-mediated channel block is highly regulated by processes that control the free cytoplasmic polyamine concentration, the membrane potential, or the iGluR subunit composition. Recently, an additional regulation by auxiliary proteins, most notably transmembrane AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor regulatory proteins (TARPs), cornichons, and neuropilin and tolloid-like proteins (NETOs), has been identified. Here, I review what we have learned of polyamine block of iGluRs and its regulation by auxiliary subunits. TARPs, cornichons, and NETOs attenuate the channel block by enabling polyamines to exit the pore. As a result, polyamine permeation occurs at more negative and physiologically relevant membrane potentials. The structural basis for enhanced polyamine transport remains unresolved, although alterations in both channel architecture and charge-screening mechanisms have been proposed. That auxiliary subunits can attenuate the polyamine block reveals an unappreciated impact of polyamine permeation in shaping the signaling properties of neuronal AMPA- and kainate-type iGluRs. Moreover, enhanced polyamine transport through iGluRs may have a role in regulating cellular polyamine levels.
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Affiliation(s)
- Derek Bowie
- From the Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec H3G 0B1, Canada
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67
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Liu YT, Chen YC, Kwan SY, Chou CC, Yu HY, Yen DJ, Liao KK, Chen WT, Lin YY, Chen RS, Jih KY, Lu SF, Wu YT, Wang PS, Hsiao FJ. Aberrant Sensory Gating of the Primary Somatosensory Cortex Contributes to the Motor Circuit Dysfunction in Paroxysmal Kinesigenic Dyskinesia. Front Neurol 2018; 9:831. [PMID: 30386286 PMCID: PMC6198142 DOI: 10.3389/fneur.2018.00831] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 09/18/2018] [Indexed: 12/19/2022] Open
Abstract
Paroxysmal kinesigenic dyskinesia (PKD) is conventionally regarded as a movement disorder (MD) and characterized by episodic hyperkinesia by sudden movements. However, patients of PKD often have sensory aura and respond excellently to antiepileptic agents. PRRT2 mutations, the most common genetic etiology of PKD, could cause epilepsy syndromes as well. Standing in the twilight zone between MDs and epilepsy, the pathogenesis of PKD is unclear. Gamma oscillations arise from the inhibitory interneurons which are crucial in the thalamocortical circuits. The role of synchronized gamma oscillations in sensory gating is an important mechanism of automatic cortical inhibition. The patterns of gamma oscillations have been used to characterize neurophysiological features of many neurological diseases, including epilepsy and MDs. This study was aimed to investigate the features of gamma synchronizations in PKD. In the paired-pulse electrical-stimulation task, we recorded the magnetoencephalographic data with distributed source modeling and time-frequency analysis in 19 patients of newly-diagnosed PKD without receiving pharmacotherapy and 18 healthy controls. In combination with the magnetic resonance imaging, the source of gamma oscillations was localized in the primary somatosensory cortex. Somatosensory evoked fields of PKD patients had a reduced peak frequency (p < 0.001 for the first and the second response) and a prolonged peak latency (the first response p = 0.02, the second response p = 0.002), indicating the synchronization of gamma oscillation is significantly attenuated. The power ratio between two responses was much higher in the PKD group (p = 0.013), indicating the incompetence of activity suppression. Aberrant gamma synchronizations revealed the defective sensory gating of the somatosensory area contributes the pathogenesis of PKD. Our findings documented disinhibited cortical function is a pathomechanism common to PKD and epilepsy, thus rationalized the clinical overlaps of these two diseases and the therapeutic effect of antiepileptic agents for PKD. There is a greater reduction of the peak gamma frequency in PRRT2-related PKD than the non-PRRT PKD group (p = 0.028 for the first response, p = 0.004 for the second response). Loss-of-function PRRT2 mutations could lead to synaptic dysfunction. The disinhibiton change on neurophysiology reflected the impacts of PRRT2 mutations on human neurophysiology.
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Affiliation(s)
- Yo-Tsen Liu
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Chieh Chen
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Shang-Yeong Kwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chien-Chen Chou
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Hsiang-Yu Yu
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Der-Jen Yen
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Kwong-Kum Liao
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Wei-Ta Chen
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Yung-Yang Lin
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Critical Care Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Rou-Shayn Chen
- Department of Neurology, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Kang-Yang Jih
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Shu-Fen Lu
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yu-Te Wu
- Brain Research Center, National Yang-Ming University, Taipei, Taiwan.,Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Po-Shan Wang
- Faculty of Medicine, National Yang-Ming University, Taipei, Taiwan.,Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan.,Department of Neurology, Taipei Municipal Gan-Dau Hospital, Taipei, Taiwan
| | - Fu-Jung Hsiao
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan
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68
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Lalanne T, Oyrer J, Farrant M, Sjöström PJ. Synapse Type-Dependent Expression of Calcium-Permeable AMPA Receptors. Front Synaptic Neurosci 2018; 10:34. [PMID: 30369875 PMCID: PMC6194349 DOI: 10.3389/fnsyn.2018.00034] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 09/24/2018] [Indexed: 12/13/2022] Open
Abstract
Calcium-permeable (CP) AMPA-type glutamate receptors (AMPARs) are known to mediate synaptic plasticity in several different interneuron (IN) types. Recent evidence suggests that CP-AMPARs are synapse-specifically expressed at excitatory connections onto a subset of IN types in hippocampus and neocortex. For example, CP-AMPARs are found at connections from pyramidal cells (PCs) to basket cells (BCs), but not to Martinotti cells (MCs). This synapse type-specific expression of CP-AMPARs suggests that synaptic dynamics as well as learning rules are differentially implemented in local circuits and has important implications not just in health but also in disease states such as epilepsy.
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Affiliation(s)
- Txomin Lalanne
- Department of Biomedicine, Institute of Physiology, University of Basel, Basel, Switzerland
| | - Julia Oyrer
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Mark Farrant
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - P Jesper Sjöström
- Centre for Research in Neuroscience, Department of Neurology and Neurosurgery, Brain Repair and Integrative Neuroscience Program, Montreal General Hospital, The Research Institute of the McGill University Health Centre, Montreal, QC, Canada
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69
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Rozov A, Zakharova Y, Vazetdinova A, Valiullina-Rakhmatullina F. The Role of Polyamine-Dependent Facilitation of Calcium Permeable AMPARs in Short-Term Synaptic Enhancement. Front Cell Neurosci 2018; 12:345. [PMID: 30364146 PMCID: PMC6191566 DOI: 10.3389/fncel.2018.00345] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 09/18/2018] [Indexed: 11/13/2022] Open
Abstract
Depending on subunit composition AMPA receptor channels can be subdivided into two groups: GluA2-containing calcium impermeable AMPARs, and GluA2-lacking calcium permeable, AMPARs. These two groups differ in a number of biophysical properties and, most likely, in their functional role at glutamatergic synapses. GluA2-lacking channels have received a lot of attention over the last two decades mainly due to high calcium permeability, which was suggested to play a significant role in the induction of long-term synaptic plasticity in healthy tissue and neuronal death under neuropathological conditions. However, calcium permeable AMPARs possess another property that can contribute substantially to frequency dependent dynamics of synaptic efficacy. In the closed state calcium permeable AMPARs are blocked by endogenous polyamines, however, repetitive activation leads to progressive relief from the block and to the facilitation of ion flux through these channels. Polyamine-dependent facilitation of AMPARs can contribute to short-term plasticity at synapses that have high initial release probability and express calcium permeable AMPARs. During synaptic transmission activity-dependent relief from polyamine block of postsynaptic calcium-permeable AMPARs either counteracts presynaptic short-term depression in a frequency-dependent manner or, under specific stimulation conditions, induces facilitation of a synaptic response. Taking into account the fact that expression of calcium permeable AMPARs is developmentally regulated, depends on network activity and increases in diseased brain states, polyamine-dependent facilitation of calcium permeable AMPARs is an important, entirely postsynaptic mechanism of synaptic gain regulation.
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Affiliation(s)
- Andrei Rozov
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia.,Department of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Yulia Zakharova
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
| | - Alina Vazetdinova
- Laboratory of Neurobiology, Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia
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70
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Phosphorylation of the AMPAR-TARP Complex in Synaptic Plasticity. Proteomes 2018; 6:proteomes6040040. [PMID: 30297624 PMCID: PMC6313930 DOI: 10.3390/proteomes6040040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/04/2018] [Accepted: 10/06/2018] [Indexed: 11/17/2022] Open
Abstract
Synaptic plasticity has been considered a key mechanism underlying many brain functions including learning, memory, and drug addiction. An increase or decrease in synaptic activity of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) complex mediates the phenomena as shown in the cellular models of synaptic plasticity, long-term potentiation (LTP), and depression (LTD). In particular, protein phosphorylation shares the spotlight in expressing the synaptic plasticity. This review summarizes the studies on phosphorylation of the AMPAR pore-forming subunits and auxiliary proteins including transmembrane AMPA receptor regulatory proteins (TARPs) and discusses its role in synaptic plasticity.
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71
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Jacobi E, von Engelhardt J. AMPA receptor complex constituents: Control of receptor assembly, membrane trafficking and subcellular localization. Mol Cell Neurosci 2018; 91:67-75. [DOI: 10.1016/j.mcn.2018.05.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 11/29/2022] Open
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72
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Gratacòs-Batlle E, Olivella M, Sánchez-Fernández N, Yefimenko N, Miguez-Cabello F, Fadó R, Casals N, Gasull X, Ambrosio S, Soto D. Mechanisms of CPT1C-Dependent AMPAR Trafficking Enhancement. Front Mol Neurosci 2018; 11:275. [PMID: 30135643 PMCID: PMC6092487 DOI: 10.3389/fnmol.2018.00275] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 07/20/2018] [Indexed: 12/19/2022] Open
Abstract
In neurons, AMPA receptor (AMPAR) function depends essentially on their constituent components:the ion channel forming subunits and ion channel associated proteins. On the other hand, AMPAR trafficking is tightly regulated by a vast number of intracellular neuronal proteins that bind to AMPAR subunits. It has been recently shown that the interaction between the GluA1 subunit of AMPARs and carnitine palmitoyltransferase 1C (CPT1C), a novel protein partner of AMPARs, is important in modulating surface expression of these ionotropic glutamate receptors. Indeed, synaptic transmission in CPT1C knockout (KO) mice is diminished supporting a positive trafficking role for that protein. However, the molecular mechanisms of such modulation remain unknown although a putative role of CPT1C in depalmitoylating GluA1 has been hypothesized. Here, we explore that possibility and show that CPT1C effect on AMPARs is likely due to changes in the palmitoylation state of GluA1. Based on in silico analysis, Ser 252, His 470 and Asp 474 are predicted to be the catalytic triad responsible for CPT1C palmitoyl thioesterase (PTE) activity. When these residues are mutated or when PTE activity is inhibited, the CPT1C effect on AMPAR trafficking is abolished, validating the CPT1C catalytic triad as being responsible for PTE activity on AMPAR. Moreover, the histidine residue (His 470) of CPT1C is crucial for the increase in GluA1 surface expression in neurons and the H470A mutation impairs the depalmitoylating catalytic activity of CPT1C. Finally, we show that CPT1C effect seems to be specific for this CPT1 isoform and it takes place solely at endoplasmic reticulum (ER). This work adds another facet to the impressive degree of molecular mechanisms regulating AMPAR physiology.
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Affiliation(s)
- Esther Gratacòs-Batlle
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Mireia Olivella
- Grup de Recerca en Bioinformàtica i Estadística Mèdica, Universitat de Vic, Barcelona, Spain
| | - Nuria Sánchez-Fernández
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Natalia Yefimenko
- Laboratori de Neurobiologia, Department de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, Campus Universitari de Bellvitge, Universitat de Barcelona, Barcelona, Spain
| | - Federico Miguez-Cabello
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Rut Fadó
- Department de Ciències Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Barcelona, Spain
| | - Núria Casals
- Department de Ciències Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Barcelona, Spain
| | - Xavier Gasull
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Santiago Ambrosio
- Unitat de Bioquímica, Departament de Ciències Fisiològiques, Facultat de Medicina i Ciències de la Salut, Campus Universitari de Bellvitge, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques de Bellvitge (IDIBELL), Barcelona, Spain
| | - David Soto
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
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73
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Athie MCP, Vieira AS, Teixeira JM, dos Santos GG, Dias EV, Tambeli CH, Sartori CR, Parada CA. Transcriptome analysis of dorsal root ganglia's diabetic neuropathy reveals mechanisms involved in pain and regeneration. Life Sci 2018; 205:54-62. [DOI: 10.1016/j.lfs.2018.05.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/26/2018] [Accepted: 05/06/2018] [Indexed: 11/15/2022]
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74
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Dual Effects of TARP γ-2 on Glutamate Efficacy Can Account for AMPA Receptor Autoinactivation. Cell Rep 2018; 20:1123-1135. [PMID: 28768197 PMCID: PMC5554777 DOI: 10.1016/j.celrep.2017.07.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/12/2017] [Accepted: 07/09/2017] [Indexed: 11/10/2022] Open
Abstract
Fast excitatory transmission in the CNS is mediated mainly by AMPA-type glutamate receptors (AMPARs) associated with transmembrane AMPAR regulatory proteins (TARPs). At the high glutamate concentrations typically seen during synaptic transmission, TARPs slow receptor desensitization and enhance mean channel conductance. However, their influence on channels gated by low glutamate concentrations, as encountered during delayed transmitter clearance or synaptic spillover, is poorly understood. We report here that TARP γ-2 reduces the ability of low glutamate concentrations to cause AMPAR desensitization and enhances channel gating at low glutamate occupancy. Simulations show that, by shifting the balance between AMPAR activation and desensitization, TARPs can markedly facilitate the transduction of spillover-mediated synaptic signaling. Furthermore, the dual effects of TARPs can account for biphasic steady-state glutamate concentration-response curves—a phenomenon termed “autoinactivation,” previously thought to reflect desensitization-mediated AMPAR/TARP dissociation. TARP γ-2 reduces desensitization and enhances the gating of singly liganded AMPARs This accounts for biphasic steady-state dose-response curves (autoinactivation) The effects of γ-2 are predicted to enhance synaptic spillover currents Desensitization does not lead to functional dissociation of the AMPAR/TARP complex
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75
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Matt L, Kirk LM, Chenaux G, Speca DJ, Puhger KR, Pride MC, Qneibi M, Haham T, Plambeck KE, Stern-Bach Y, Silverman JL, Crawley JN, Hell JW, Díaz E. SynDIG4/Prrt1 Is Required for Excitatory Synapse Development and Plasticity Underlying Cognitive Function. Cell Rep 2018; 22:2246-2253. [PMID: 29490264 PMCID: PMC5856126 DOI: 10.1016/j.celrep.2018.02.026] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/15/2017] [Accepted: 02/06/2018] [Indexed: 11/19/2022] Open
Abstract
Altering AMPA receptor (AMPAR) content at synapses is a key mechanism underlying the regulation of synaptic strength during learning and memory. Previous work demonstrated that SynDIG1 (synapse differentiation-induced gene 1) encodes a transmembrane AMPAR-associated protein that regulates excitatory synapse strength and number. Here we show that the related protein SynDIG4 (also known as Prrt1) modifies AMPAR gating properties in a subunit-dependent manner. Young SynDIG4 knockout (KO) mice have weaker excitatory synapses, as evaluated by immunocytochemistry and electrophysiology. Adult SynDIG4 KO mice show complete loss of tetanus-induced long-term potentiation (LTP), while mEPSC amplitude is reduced by only 25%. Furthermore, SynDIG4 KO mice exhibit deficits in two independent cognitive assays. Given that SynDIG4 colocalizes with the AMPAR subunit GluA1 at non-synaptic sites, we propose that SynDIG4 maintains a pool of extrasynaptic AMPARs necessary for synapse development and function underlying higher-order cognitive plasticity.
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Affiliation(s)
- Lucas Matt
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - Lyndsey M Kirk
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - George Chenaux
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - David J Speca
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - Kyle R Puhger
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Michael C Pride
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Mohammad Qneibi
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Tomer Haham
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | | | - Yael Stern-Bach
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Jill L Silverman
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Jacqueline N Crawley
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Johannes W Hell
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA.
| | - Elva Díaz
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA.
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76
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Liu YT, Nian FS, Chou WJ, Tai CY, Kwan SY, Chen C, Kuo PW, Lin PH, Chen CY, Huang CW, Lee YC, Soong BW, Tsai JW. PRRT2 mutations lead to neuronal dysfunction and neurodevelopmental defects. Oncotarget 2018; 7:39184-39196. [PMID: 27172900 PMCID: PMC5129924 DOI: 10.18632/oncotarget.9258] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/26/2016] [Indexed: 11/25/2022] Open
Abstract
Mutations in the proline-rich transmembrane protein 2 (PRRT2) gene cause a wide spectrum of neurological diseases, ranging from paroxysmal kinesigenic dyskinesia (PKD) to mental retardation and epilepsy. Previously, seven PKD-related PRRT2 heterozygous mutations were identified in the Taiwanese population: P91QfsX, E199X, S202HfsX, R217PfsX, R217EfsX, R240X and R308C. This study aimed to investigate the disease-causing mechanisms of these PRRT2 mutations. We first documented that Prrt2 was localized at the pre- and post-synaptic membranes with a close spatial association with SNAP25 by synaptic membrane fractionation and immunostaining of the rat neurons. Our results then revealed that the six truncating Prrt2 mutants were accumulated in the cytoplasm and thus failed to target to the cell membrane; the R308C missense mutant had significantly reduced protein expression, suggesting loss-of function effects generated by these mutations. Using in utero electroporation of shRNA into cortical neurons, we further found that knocking down Prrt2 expression in vivo resulted in a delay in neuronal migration during embryonic development and a marked decrease in synaptic density after birth. These pathologic effects and novel disease-causing mechanisms may contribute to the severe clinical symptoms in PRRT2–related diseases.
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Affiliation(s)
- Yo-Tsen Liu
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Fang-Shin Nian
- Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan.,Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Wan-Ju Chou
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Chin-Yin Tai
- Istitute of Pharmaceutics, Development Center for Biotechnology, New Taipei City, Taiwan
| | - Shang-Yeong Kwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Chien Chen
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Pei-Wen Kuo
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Po-Hsi Lin
- Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan
| | - Chin-Yi Chen
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Chia-Wei Huang
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Chung Lee
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Bing-Wen Soong
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Neurology, National Yang-Ming University School of Medicine, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Jin-Wu Tsai
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan.,Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan
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77
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CKAMP44 modulates integration of visual inputs in the lateral geniculate nucleus. Nat Commun 2018; 9:261. [PMID: 29343769 PMCID: PMC5772470 DOI: 10.1038/s41467-017-02415-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 11/25/2017] [Indexed: 11/08/2022] Open
Abstract
Relay neurons in the dorsal lateral geniculate nucleus (dLGN) receive excitatory inputs from retinal ganglion cells (RGCs). Retinogeniculate synapses are characterized by a prominent short-term depression of AMPA receptor (AMPAR)-mediated currents, but the underlying mechanisms and its function for visual integration are not known. Here we identify CKAMP44 as a crucial auxiliary subunit of AMPARs in dLGN relay neurons, where it increases AMPAR-mediated current amplitudes and modulates gating of AMPARs. Importantly, CKAMP44 is responsible for the distinctive short-term depression in retinogeniculate synapses by reducing the rate of recovery from desensitization of AMPARs. Genetic deletion of CKAMP44 strongly reduces synaptic short-term depression, which leads to increased spike probability of relay neurons when activated with high-frequency inputs from retinogeniculate synapses. Finally, in vivo recordings reveal augmented ON- and OFF-responses of dLGN neurons in CKAMP44 knockout (CKAMP44−/−) mice, demonstrating the importance of CKAMP44 for modulating synaptic short-term depression and visual input integration. The function of receptor desensitization in vivo is not well understood. Here, the authors show that deletion of CKAMP44, an AMPAR auxiliary protein that modulates desensitization of AMPAR currents, affects synaptic facilitation at retinogeniculate synapses and visually-evoked firing in awake mice.
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78
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Han W, Wang H, Li J, Zhang S, Lu W. Ferric Chelate Reductase 1 Like Protein (FRRS1L) Associates with Dynein Vesicles and Regulates Glutamatergic Synaptic Transmission. Front Mol Neurosci 2017; 10:402. [PMID: 29276473 PMCID: PMC5727121 DOI: 10.3389/fnmol.2017.00402] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 11/20/2017] [Indexed: 12/23/2022] Open
Abstract
In the brain, AMPA receptors (AMPARs)-mediated excitatory synaptic transmission is critically regulated by the receptor auxiliary subunits. Recent proteomic studies have identified that Ferric Chelate Reductase 1 Like protein (FRRS1L), whose mutations in human lead to epilepsy, choreoathetosis, and cognitive deficits, is present in native AMPAR complexes in the brain. Here we have characterized FRRS1L in both heterologous cells and in mouse neurons. We found that FRRS1L interacts with both GluA1 and GluA2 subunits of AMPARs, but does not form dimers/oligomers, in HEK cells. In mouse hippocampal neurons, recombinant FRRS1L at the neuronal surface partially co-localizes with GluA1 and primarily localizes at non-synaptic membranes. In addition, native FRRS1L in hippocampus is localized at dynein, but not kinesin5B, vesicles. Functionally, over-expression of FRRS1L in hippocampal neurons does not change glutamatergic synaptic transmission. In contrast, single-cell knockout (KO) of FRRS1L strongly reduces the expression levels of the GluA1 subunit at the neuronal surface, and significantly decreases AMPAR-mediated synaptic transmission in mouse hippocampal pyramidal neurons. Taken together, these data characterize FRRS1L in heterologous cells and neurons, and reveal an important role of FRRS1L in the regulation of excitatory synaptic strength.
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Affiliation(s)
- Wenyan Han
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Huiqing Wang
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States.,Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.,Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Jun Li
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Shizhong Zhang
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Wei Lu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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79
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Schmitz LJM, Klaassen RV, Ruiperez-Alonso M, Zamri AE, Stroeder J, Rao-Ruiz P, Lodder JC, van der Loo RJ, Mansvelder HD, Smit AB, Spijker S. The AMPA receptor-associated protein Shisa7 regulates hippocampal synaptic function and contextual memory. eLife 2017; 6:24192. [PMID: 29199957 PMCID: PMC5737659 DOI: 10.7554/elife.24192] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 12/02/2017] [Indexed: 12/20/2022] Open
Abstract
Glutamatergic synapses rely on AMPA receptors (AMPARs) for fast synaptic transmission and plasticity. AMPAR auxiliary proteins regulate receptor trafficking, and modulate receptor mobility and its biophysical properties. The AMPAR auxiliary protein Shisa7 (CKAMP59) has been shown to interact with AMPARs in artificial expression systems, but it is unknown whether Shisa7 has a functional role in glutamatergic synapses. We show that Shisa7 physically interacts with synaptic AMPARs in mouse hippocampus. Shisa7 gene deletion resulted in faster AMPAR currents in CA1 synapses, without affecting its synaptic expression. Shisa7 KO mice showed reduced initiation and maintenance of long-term potentiation of glutamatergic synapses. In line with this, Shisa7 KO mice showed a specific deficit in contextual fear memory, both short-term and long-term after conditioning, whereas auditory fear memory and anxiety-related behavior were normal. Thus, Shisa7 is a bona-fide AMPAR modulatory protein affecting channel kinetics of AMPARs, necessary for synaptic hippocampal plasticity, and memory recall.
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Affiliation(s)
- Leanne J M Schmitz
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands.,Sylics (Synaptologics BV), Amsterdam, The Netherlands
| | - Remco V Klaassen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Marta Ruiperez-Alonso
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Azra Elia Zamri
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands.,Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France
| | - Jasper Stroeder
- Sylics (Synaptologics BV), Amsterdam, The Netherlands.,Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Priyanka Rao-Ruiz
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Johannes C Lodder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Rolinka J van der Loo
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands.,Sylics (Synaptologics BV), Amsterdam, The Netherlands
| | - Huib D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Sabine Spijker
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
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80
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Savas JN, Wang YZ, DeNardo LA, Martinez-Bartolome S, McClatchy DB, Hark TJ, Shanks NF, Cozzolino KA, Lavallée-Adam M, Smukowski SN, Park SK, Kelly JW, Koo EH, Nakagawa T, Masliah E, Ghosh A, Yates JR. Amyloid Accumulation Drives Proteome-wide Alterations in Mouse Models of Alzheimer's Disease-like Pathology. Cell Rep 2017; 21:2614-2627. [PMID: 29186695 PMCID: PMC5726791 DOI: 10.1016/j.celrep.2017.11.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 09/26/2017] [Accepted: 11/01/2017] [Indexed: 10/18/2022] Open
Abstract
Amyloid beta (Aβ) peptides impair multiple cellular pathways and play a causative role in Alzheimer's disease (AD) pathology, but how the brain proteome is remodeled by this process is unknown. To identify protein networks associated with AD-like pathology, we performed global quantitative proteomic analysis in three mouse models at young and old ages. Our analysis revealed a robust increase in Apolipoprotein E (ApoE) levels in nearly all brain regions with increased Aβ levels. Taken together with prior findings on ApoE driving Aβ accumulation, this analysis points to a pathological dysregulation of the ApoE-Aβ axis. We also found dysregulation of protein networks involved in excitatory synaptic transmission. Analysis of the AMPA receptor (AMPAR) complex revealed specific loss of TARPγ-2, a key AMPAR-trafficking protein. Expression of TARPγ-2 in hAPP transgenic mice restored AMPA currents. This proteomic database represents a resource for the identification of protein alterations responsible for AD.
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Affiliation(s)
- Jeffrey N Savas
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Yi-Zhi Wang
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Laura A DeNardo
- Neurobiology Section, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | | | - Daniel B McClatchy
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Timothy J Hark
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Natalie F Shanks
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kira A Cozzolino
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Mathieu Lavallée-Adam
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Biochemistry, Microbiology and Immunology and Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Samuel N Smukowski
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sung Kyu Park
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jeffery W Kelly
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Edward H Koo
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Terunaga Nakagawa
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Eliezer Masliah
- Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Anirvan Ghosh
- Neurobiology Section, Division of Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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81
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Nakaya N, Sultana A, Tomarev SI. Impaired AMPA receptor trafficking by a double knockout of zebrafish olfactomedin1a/b. J Neurochem 2017; 143:635-644. [PMID: 28975619 DOI: 10.1111/jnc.14231] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/15/2017] [Accepted: 09/27/2017] [Indexed: 01/06/2023]
Abstract
The olfm1a and olfm1b genes in zebrafish encode conserved secreted glycoproteins. These genes are preferentially expressed in the brain and retina starting from 16 h post-fertilization until adulthood. Functions of the Olfm1 gene is still unclear. Here, we produced and analyzed a null zebrafish mutant of both olfm1a and olfm1b genes (olfm1 null). olfm1 null fish were born at a normal Mendelian ratio and showed normal body shape and fertility as well as no visible defects from larval stages to adult. Olfm1 proteins were preferentially localized in the synaptosomes of the adult brain. Olfm1 co-immunoprecipitated with GluR2 and soluble NSF attachment protein receptor complexes indicating participation of Olfm1 in both pre- and post-synaptic events. Phosphorylation of GluR2 was not changed while palmitoylation of GluR2 was decreased in the brain synaptosomal membrane fraction of olfm1 null compared with wt fish. The levels of GluR2, SNAP25, flotillin1, and VAMP2 were markedly reduced in the synaptic microdomain of olfm1 null brain compared with wt. The internalization of GluR2 in retinal cells and the localization of VAMP2 in brain synaptosome were modified by olfm1 null mutation. This indicates that Olfm1 may regulate receptor trafficking from the intracellular compartments to the synaptic membrane microdomain, partly through the alteration of post-translational GluR2 modifications such as palmitoylation. Olfm1 may be considered a novel regulator of the composition and function of the α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor complex.
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Affiliation(s)
- Naoki Nakaya
- Section of Retinal Ganglion Cell Biology, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, NIH, Bethesda, Maryland, USA
| | - Afia Sultana
- Section of Retinal Ganglion Cell Biology, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, NIH, Bethesda, Maryland, USA
| | - Stanislav I Tomarev
- Section of Retinal Ganglion Cell Biology, Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, NIH, Bethesda, Maryland, USA
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82
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Abstract
![]()
Ionotropic
glutamate receptors (iGluRs) are ligand-gated ion channels
that mediate the majority of excitatory neurotransmission in the central
nervous system. iGluRs open their ion channels in response to binding
of the neurotransmitter glutamate, rapidly depolarize the postsynaptic
neuronal membrane, and initiate signal transduction. Recent studies
using X-ray crystallography and cryo-electron microscopy have determined
full-length iGluR structures that (1) uncover the receptor architecture
in an unliganded, resting state, (2) reveal conformational changes
produced by ligands in order to activate iGluRs, open their ion channels,
and conduct ions, and (3) show how activated, glutamate-bound iGluRs
can adopt a nonconducting desensitized state. These new findings,
combined with the results of previous structural and functional experiments,
kinetic and molecular modeling, mutagenesis, and biochemical analyses,
provide new views on the structural mechanisms of iGluR gating.
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Affiliation(s)
- Edward C Twomey
- Department of Biochemistry and Molecular Biophysics and ‡Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University , 650 West 168th Street, New York, New York 10032, United States
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics and ‡Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University , 650 West 168th Street, New York, New York 10032, United States
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83
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Kato AS, Witkin JM. Auxiliary subunits of AMPA receptors: The discovery of a forebrain-selective antagonist, LY3130481/CERC-611. Biochem Pharmacol 2017; 147:191-200. [PMID: 28987594 DOI: 10.1016/j.bcp.2017.09.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 09/27/2017] [Indexed: 12/11/2022]
Abstract
Drugs originate from the discovery of compounds, natural or synthetic, that bind to proteins (receptors, enzymes, transporters, etc.), the interaction of which modulates biological cascades that have potential therapeutic benefit. Rational strategies for identifying novel drug therapies are typically based on knowledge of the structure of the target proteins and the design of new chemical entities that modulate these proteins in a beneficial manner. The present review discusses a novel approach to drug discovery based on the identification and characterization of auxiliary proteins, the transmembrane AMPA receptor regulatory proteins (TARPs) that are associated with AMPA receptors. Utilizing these auxiliary proteins in compound screening led to the discovery of the TARP-dependent-AMPA forebrain selective receptor antagonist (TDAA), LY3130481/CERC-611 that is currently in clinical development for epilepsy.
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Affiliation(s)
- Akihiko S Kato
- Neuroscience Discovery Research, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN 46285-0510, United States.
| | - Jeffrey M Witkin
- Neuroscience Discovery Research, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN 46285-0510, United States.
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84
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Hawken NM, Zaika EI, Nakagawa T. Engineering defined membrane-embedded elements of AMPA receptor induces opposing gating modulation by cornichon 3 and stargazin. J Physiol 2017; 595:6517-6539. [PMID: 28815591 DOI: 10.1113/jp274897] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 08/04/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The AMPA-type ionotropic glutamate receptors (AMPARs) mediate the majority of excitatory synaptic transmission and their function impacts learning, cognition and behaviour. The gating of AMPARs occurs in milliseconds, precisely controlled by a variety of auxiliary subunits that are expressed differentially in the brain, but the difference in mechanisms underlying AMPAR gating modulation by auxiliary subunits remains elusive and is investigated. The elements of the AMPAR that are functionally recruited by auxiliary subunits, stargazin and cornichon 3, are located not only in the extracellular domains but also in the lipid-accessible surface of the AMPAR. We reveal that the two auxiliary subunits require a shared surface on the transmembrane domain of the AMPAR for their function, but the gating is influenced by this surface in opposing directions for each auxiliary subunit. Our results provide new insights into the mechanistic difference of AMPAR modulation by auxiliary subunits and a conceptual framework for functional engineering of the complex. ABSTRACT During excitatory synaptic transmission, various structurally unrelated transmembrane auxiliary subunits control the function of AMPA receptors (AMPARs), but the underlying mechanisms remain unclear. We identified lipid-exposed residues in the transmembrane domain (TMD) of the GluA2 subunit of AMPARs that are critical for the function of AMPAR auxiliary subunits, stargazin (Stg) and cornichon 3 (CNIH3). These residues are essential for stabilizing the AMPAR-CNIH3 complex in detergents and overlap with the contacts made between GluA2 TMD and Stg in the cryoEM structures. Mutating these residues had opposite effects on gating modulation and complex stability when Stg- and CNIH3-bound AMPARs were compared. Specifically, in detergent the GluA2-A793F formed an unstable complex with CNIIH3 but in the membrane the GluA2-A793F-CNIH3 complex expressed a gain of function. In contrast, the GluA2-A793F-Stg complex was stable, but had diminished gating modulation. GluA2-C528L destabilized the AMPAR-CNIH3 complex but stabilized the AMPAR-Stg complex, with overall loss of function in gating modulation. Furthermore, loss-of-function mutations in this TMD region cancelled the effects of a gain-of-function Stg carrying mutation in its extracellular loop, demonstrating that both the extracellular and the TMD elements contribute independently to gating modulation. The elements of AMPAR functionally recruited by auxiliary subunits are, therefore, located not only in the extracellular domains but also in the lipid accessible surface of the AMPAR. The TMD surface we defined is a potential target for auxiliary subunit-specific compounds, because engineering of this hotspot induces opposing functional outcomes by Stg and CNIH3. The collection of mutant-phenotype mapping provides a framework for engineering AMPAR gating using auxiliary subunits.
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Affiliation(s)
- Natalie M Hawken
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
| | - Elena I Zaika
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Center for Structural Biology, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
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85
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Riva I, Eibl C, Volkmer R, Carbone AL, Plested AJ. Control of AMPA receptor activity by the extracellular loops of auxiliary proteins. eLife 2017; 6:28680. [PMID: 28871958 PMCID: PMC5599240 DOI: 10.7554/elife.28680] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 08/28/2017] [Indexed: 11/13/2022] Open
Abstract
At synapses throughout the mammalian brain, AMPA receptors form complexes with auxiliary proteins, including TARPs. However, how TARPs modulate AMPA receptor gating remains poorly understood. We built structural models of TARP-AMPA receptor complexes for TARPs γ2 and γ8, combining recent structural studies and de novo structure predictions. These models, combined with peptide binding assays, provide evidence for multiple interactions between GluA2 and variable extracellular loops of TARPs. Substitutions and deletions of these loops had surprisingly rich effects on the kinetics of glutamate-activated currents, without any effect on assembly. Critically, by altering the two interacting loops of γ2 and γ8, we could entirely remove all allosteric modulation of GluA2, without affecting formation of AMPA receptor-TARP complexes. Likewise, substitutions in the linker domains of GluA2 completely removed any effect of γ2 on receptor kinetics, indicating a dominant role for this previously overlooked site proximal to the AMPA receptor channel gate.
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Affiliation(s)
- Irene Riva
- Institute of Biology, Cellular Biophysics, Humboldt Universität zu Berlin, Berlin, Germany.,Molecular Physiology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Clarissa Eibl
- Institute of Biology, Cellular Biophysics, Humboldt Universität zu Berlin, Berlin, Germany.,Molecular Physiology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Rudolf Volkmer
- Chemical Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Anna L Carbone
- Institute of Biology, Cellular Biophysics, Humboldt Universität zu Berlin, Berlin, Germany.,Molecular Physiology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
| | - Andrew Jr Plested
- Institute of Biology, Cellular Biophysics, Humboldt Universität zu Berlin, Berlin, Germany.,Molecular Physiology and Cell Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
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86
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The Challenge of Interpreting Glutamate-Receptor Ion-Channel Structures. Biophys J 2017; 113:2143-2151. [PMID: 28844473 DOI: 10.1016/j.bpj.2017.07.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/12/2017] [Accepted: 07/25/2017] [Indexed: 11/24/2022] Open
Abstract
Ion channels activated by glutamate mediate excitatory synaptic transmission in the central nervous system. Similar to other ligand-gated ion channels, their gating cycle begins with transitions from a ligand-free closed state to glutamate-bound active and desensitized states. In an attempt to reveal the molecular mechanisms underlying gating, numerous structures for glutamate receptors have been solved in complexes with agonists, antagonists, allosteric modulators, and auxiliary proteins. The embarrassingly rich library of structures emerging from this work reveals very dynamic molecules with a more complex conformational spectrum than anticipated from functional studies. Unanticipated conformations solved for complexes with competitive antagonists and a lack of understanding of the structural basis for ion channel subconductance states further highlight challenges that have yet to be addressed.
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87
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Diversity in AMPA receptor complexes in the brain. Curr Opin Neurobiol 2017; 45:32-38. [DOI: 10.1016/j.conb.2017.03.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 02/28/2017] [Accepted: 03/03/2017] [Indexed: 11/23/2022]
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88
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Frank RA, Grant SG. Supramolecular organization of NMDA receptors and the postsynaptic density. Curr Opin Neurobiol 2017; 45:139-147. [PMID: 28577431 PMCID: PMC5557338 DOI: 10.1016/j.conb.2017.05.019] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/02/2017] [Accepted: 05/15/2017] [Indexed: 01/21/2023]
Abstract
The postsynaptic density (PSD) of all vertebrate species share a highly complex proteome with ∼1000 conserved proteins that function as sophisticated molecular computational devices. Here, we review recent studies showing that this complexity can be understood in terms of the supramolecular organization of proteins, which self-assemble within a hierarchy of different length scales, including complexes, supercomplexes and nanodomains. We highlight how genetic and biochemical approaches in mice are being used to uncover the native molecular architecture of the synapse, revealing hitherto unknown molecular structures, including highly selective mechanisms for specifying the assembly of NMDAR-MAGUK supercomplexes. We propose there exists a logical framework that precisely dictates the subunit composition of synaptic complexes, supercomplexes, and nanodomains in vivo.
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Affiliation(s)
- René Aw Frank
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Seth Gn Grant
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, UK.
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89
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Twomey EC, Yelshanskaya MV, Grassucci RA, Frank J, Sobolevsky AI. Structural Bases of Desensitization in AMPA Receptor-Auxiliary Subunit Complexes. Neuron 2017; 94:569-580.e5. [PMID: 28472657 PMCID: PMC5492975 DOI: 10.1016/j.neuron.2017.04.025] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/10/2017] [Accepted: 04/17/2017] [Indexed: 02/09/2023]
Abstract
Fast excitatory neurotransmission is mediated by AMPA-subtype ionotropic glutamate receptors (AMPARs). AMPARs, localized at post-synaptic densities, are regulated by transmembrane auxiliary subunits that modulate AMPAR assembly, trafficking, gating, and pharmacology. Aberrancies in AMPAR-mediated signaling are associated with numerous neurological disorders. Here, we report cryo-EM structures of an AMPAR in complex with the auxiliary subunit GSG1L in the closed and desensitized states. GSG1L favors the AMPAR desensitized state, where channel closure is facilitated by profound structural rearrangements in the AMPAR extracellular domain, with ligand-binding domain dimers losing their local 2-fold rotational symmetry. Our structural and functional experiments suggest that AMPAR auxiliary subunits share a modular architecture and use a common transmembrane scaffold for distinct extracellular modules to differentially regulate AMPAR gating. By comparing the AMPAR-GSG1L complex structures, we map conformational changes accompanying AMPAR recovery from desensitization and reveal structural bases for regulation of synaptic transmission by auxiliary subunits.
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Affiliation(s)
- Edward C Twomey
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA
| | - Robert A Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Howard Hughes Medical Institute, 650 West 168(th) Street, New York, NY 10032, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Department of Biological Sciences, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA; Howard Hughes Medical Institute, 650 West 168(th) Street, New York, NY 10032, USA.
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168(th) Street, New York, NY 10032, USA.
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90
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Greger IH, Watson JF, Cull-Candy SG. Structural and Functional Architecture of AMPA-Type Glutamate Receptors and Their Auxiliary Proteins. Neuron 2017; 94:713-730. [DOI: 10.1016/j.neuron.2017.04.009] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 04/04/2017] [Accepted: 04/05/2017] [Indexed: 12/20/2022]
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91
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Baucum AJ. Proteomic Analysis of Postsynaptic Protein Complexes Underlying Neuronal Plasticity. ACS Chem Neurosci 2017; 8:689-701. [PMID: 28211672 DOI: 10.1021/acschemneuro.7b00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Normal neuronal communication and synaptic plasticity at glutamatergic synapses requires dynamic regulation of postsynaptic molecules. Protein expression and protein post-translational modifications regulate protein interactions that underlie this organization. In this Review, we highlight data obtained over the last 20 years that have used qualitative and quantitative proteomics-based approaches to identify postsynaptic protein complexes. Herein, we describe how these proteomics studies have helped lay the foundation for understanding synaptic physiology and perturbations in synaptic signaling observed in different pathologies. We also describe emerging technologies that can be useful in these analyses. We focus on protein complexes associated with the highly abundant and functionally critical proteins: calcium/calmodulin-dependent protein kinase II, the N-methyl-d-aspartate, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors, and postsynaptic density protein of 95 kDa.
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Affiliation(s)
- Anthony J. Baucum
- Department of Biology, Stark Neurosciences
Research Institute, Indiana University-Purdue University Indianapolis, 723 W. Michigan St., Indianapolis, Indiana 46202, United States
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92
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Azumaya CM, Days EL, Vinson PN, Stauffer S, Sulikowski G, Weaver CD, Nakagawa T. Screening for AMPA receptor auxiliary subunit specific modulators. PLoS One 2017; 12:e0174742. [PMID: 28358902 PMCID: PMC5373622 DOI: 10.1371/journal.pone.0174742] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 03/14/2017] [Indexed: 12/18/2022] Open
Abstract
AMPA receptors (AMPAR) are ligand gated ion channels critical for synaptic transmission and plasticity. Their dysfunction is implicated in a variety of psychiatric and neurological diseases ranging from major depressive disorder to amyotrophic lateral sclerosis. Attempting to potentiate or depress AMPAR activity is an inherently difficult balancing act between effective treatments and debilitating side effects. A newly explored strategy to target subsets of AMPARs in the central nervous system is to identify compounds that affect specific AMPAR-auxiliary subunit complexes. This exploits diverse spatio-temporal expression patterns of known AMPAR auxiliary subunits, providing means for designing brain region-selective compounds. Here we report a high-throughput screening-based pipeline that can identify compounds that are selective for GluA2-CNIH3 and GluA2-stargazin complexes. These compounds will help us build upon the growing library of AMPAR-auxiliary subunit specific inhibitors, which have thus far all been targeted to TARP γ-8. We used a cell-based assay combined with a voltage-sensitive dye (VSD) to identify changes in glutamate-gated cation flow across the membranes of HEK cells co-expressing GluA2 and an auxiliary subunit. We then used a calcium flux assay to further validate hits picked from the VSD assay. VU0612951 and VU0627849 are candidate compounds from the initial screen that were identified as negative and positive allosteric modulators (NAM and PAM), respectively. They both have lower IC50/EC50s on complexes containing stargazin and CNIH3 than GSG1L or the AMPAR alone. We have also identified a candidate compound, VU0539491, that has NAM activity in GluA2(R)-CNIH3 and GluA2(Q) complexes and PAM activity in GluA2(Q)-GSG1L complexes.
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Affiliation(s)
- Caleigh M Azumaya
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Emily L Days
- Vanderbilt Institute of Chemical Biology High Throughput Screening Core, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Paige N Vinson
- Vanderbilt Institute of Chemical Biology High Throughput Screening Core, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Shaun Stauffer
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America.,Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Gary Sulikowski
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
| | - C David Weaver
- Vanderbilt Institute of Chemical Biology High Throughput Screening Core, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.,Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.,Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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93
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Subunit-specific synaptic delivery of AMPA receptors by auxiliary chaperone proteins TARPγ8 and GSG1L in classical conditioning. Neurosci Lett 2017; 645:53-59. [PMID: 28219790 DOI: 10.1016/j.neulet.2017.02.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 02/03/2017] [Accepted: 02/15/2017] [Indexed: 12/23/2022]
Abstract
AMPA receptor (AMPAR) trafficking has emerged as a fundamental concept for understanding mechanisms of learning and memory as well as many neurological disorders. Classical conditioning is a simple and highly conserved form of associative learning. Our studies use an ex vivo brainstem preparation in which to study cellular mechanisms underlying learning during a neural correlate of eyeblink conditioning. Two stages of AMPAR synaptic delivery underlie conditioning utilizing sequential trafficking of GluA1-containing AMPARs early in conditioning followed by replacement with GluA4 subunits later. Subunit-selective trafficking of AMPARs is poorly understood. Here, we focused on identification of auxiliary chaperone proteins that traffic AMPARs. The results show that auxiliary proteins TARPγ8 and GSG1L are colocalized with AMPARs on abducens motor neurons that generate the conditioning. Significantly, TARPγ8 was observed to chaperone GluA1-containing AMPARs during synaptic delivery early in conditioning while GSG1L chaperones GluA4 subunits later in conditioning. Interestingly, TARPγ8 remains at the membrane surface as GluA1 subunits are withdrawn and associates with GluA4 when they are delivered to synapses. These data indicate that GluA1- and GluA4-containing AMPARs are selectively chaperoned by TARPγ8 and GSG1L, respectively. Therefore, sequential subunit-selective trafficking of AMPARs during conditioning is achieved through the timing of their interactions with specific auxiliary proteins.
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94
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Schreiner D, Savas JN, Herzog E, Brose N, de Wit J. Synapse biology in the 'circuit-age'-paths toward molecular connectomics. Curr Opin Neurobiol 2017; 42:102-110. [PMID: 28033531 PMCID: PMC5316339 DOI: 10.1016/j.conb.2016.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 11/23/2022]
Abstract
The neural connectome is a critical determinant of brain function. Circuits of precisely wired neurons, and the features of transmission at the synapses connecting them, are thought to dictate information processing in the brain. While recent technological advances now allow to define the anatomical and functional neural connectome at unprecedented resolution, the elucidation of the molecular mechanisms that establish the precise patterns of connectivity and the functional characteristics of synapses has remained challenging. Here, we describe the power and limitations of genetic approaches in the analysis of mechanisms that control synaptic connectivity and function, and discuss how recent methodological developments in proteomics might be used to elucidate the molecular synaptic connectome that is at the basis of the neural connectome.
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Affiliation(s)
- Dietmar Schreiner
- Biozentrum, University of Basel, Klingelbergstraße 50-70, 4056 Basel, Switzerland; Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Jeffrey N Savas
- Department of Neurology, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
| | - Etienne Herzog
- Univ. Bordeaux, IINS, UMR 5297, F-33000 Bordeaux, France; CNRS, IINS, UMR 5297, F-33000 Bordeaux, France
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Straße 3, 37075 Göttingen, Germany
| | - Joris de Wit
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
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95
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Mutated olfactomedin 1 in the interphotoreceptor matrix of the mouse retina causes functional deficits and vulnerability to light damage. Histochem Cell Biol 2016; 147:453-469. [PMID: 27787612 DOI: 10.1007/s00418-016-1510-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2016] [Indexed: 12/24/2022]
Abstract
Olfactomedin 1 (OLFM1) is a secreted glycoprotein and member of the olfactomedin protein family, which is preferentially expressed in various areas throughout the central nervous system. To learn about the functional properties of OLFM1 in the eye, we investigated its localization in the mouse and pig eye. In addition, we analyzed the ocular phenotype of Olfm1 mutant mice in which 52 amino acids were deleted in the central part (M2 region) of OLFM1. OLFM1 was detected in cornea, sclera, retina, and optic nerve of both wild-type and Olfm1 mutant littermates. By immunohistochemistry and double labeling with the lectin peanut agglutinin, OLFM1 was found in the interphotoreceptor matrix (IPM) of mouse and pig retina where it was directly localized to the inner segments of photoreceptors. Western blotting confirmed the presence of the OLFM1 isoforms pancortin 1 (BMY) and pancortin 2 (BMZ) in the IPM. The retinal phenotype of Olfm1 mutant mice did not obviously differ from that of wild-type littermates. In addition, outer nuclear layer (ONL) and total retinal thickness were not different, and the same was true for the area of the optic nerve in cross sections. Functional changes were observed though by electroretinography, which showed significantly lower a- and b-wave amplitudes in Olfm1 mutant mice when compared to age-matched wild-type mice. When light damage experiments were performed as an experimental paradigm of photoreceptor apoptosis, significantly more TUNEL-positive cells were observed in Olfm1 mutant mice 30 h after light exposure. One week after light exposure, the ONL was significantly thinner in Olfm1 mutant mice than in wild-type littermates indicating increased photoreceptor loss. No differences were observed when rhodopsin turnover or ERK1/2 signaling was investigated. We conclude that OLFM1 is a newly identified IPM molecule that serves an important role for photoreceptor homeostasis, which is significantly compromised in the eyes of Olfm1 mutant mice.
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96
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Mao X, Gu X, Lu W. GSG1L regulates the strength of AMPA receptor-mediated synaptic transmission but not AMPA receptor kinetics in hippocampal dentate granule neurons. J Neurophysiol 2016; 117:28-35. [PMID: 27707810 DOI: 10.1152/jn.00307.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 10/03/2016] [Indexed: 11/22/2022] Open
Abstract
GSG1L is an AMPA receptor (AMPAR) auxiliary subunit that regulates AMPAR trafficking and function in hippocampal CA1 pyramidal neurons. However, its physiological roles in other types of neurons remain to be characterized. Here, we investigated the role of GSG1L in hippocampal dentate granule cells and found that GSG1L is important for the regulation of synaptic strength but is not critical for the modulation of AMPAR deactivation and desensitization kinetics. These data demonstrate a neuronal type-specific role of GSG1L and suggest that physiological function of AMPAR auxiliary subunits may vary in different types of neurons. NEW & NOTEWORTHY GSG1L is a newly identified AMPA receptor (AMPAR) auxiliary subunit and plays a unique role in the regulation of AMPAR trafficking and function in hippocampal CA1 pyramidal neurons. However, its role in the regulation of AMPARs in hippocampal dentate granule cells remains to be characterized. The current work reveals that GSG1L regulates strength of AMPAR-mediated synaptic transmission but not the receptor kinetic properties in hippocampal dentate granule neurons.
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Affiliation(s)
- Xia Mao
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Xinglong Gu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Wei Lu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
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97
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PRRT2: from Paroxysmal Disorders to Regulation of Synaptic Function. Trends Neurosci 2016; 39:668-679. [DOI: 10.1016/j.tins.2016.08.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/19/2016] [Accepted: 08/22/2016] [Indexed: 12/19/2022]
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98
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GluA1 signal peptide determines the spatial assembly of heteromeric AMPA receptors. Proc Natl Acad Sci U S A 2016; 113:E5645-54. [PMID: 27601647 DOI: 10.1073/pnas.1524358113] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
AMPA-type glutamate receptors (AMPARs) mediate fast excitatory neurotransmission and predominantly assemble as heterotetramers in the brain. Recently, the crystal structures of homotetrameric GluA2 demonstrated that AMPARs are assembled with two pairs of conformationally distinct subunits, in a dimer of dimers formation. However, the structure of heteromeric AMPARs remains unclear. Guided by the GluA2 structure, we performed cysteine mutant cross-linking experiments in full-length GluA1/A2, aiming to draw the heteromeric AMPAR architecture. We found that the amino-terminal domains determine the first level of heterodimer formation. When the dimers further assemble into tetramers, GluA1 and GluA2 subunits have preferred positions, possessing a 1-2-1-2 spatial assembly. By swapping the critical sequences, we surprisingly found that the spatial assembly pattern is controlled by the excisable signal peptides. Replacements with an unrelated GluK2 signal peptide demonstrated that GluA1 signal peptide plays a critical role in determining the spatial priority. Our study thus uncovers the spatial assembly of an important type of glutamate receptors in the brain and reveals a novel function of signal peptides.
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99
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SRGAP2 and Its Human-Specific Paralog Co-Regulate the Development of Excitatory and Inhibitory Synapses. Neuron 2016; 91:356-69. [PMID: 27373832 DOI: 10.1016/j.neuron.2016.06.013] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 04/12/2016] [Accepted: 05/25/2016] [Indexed: 10/21/2022]
Abstract
The proper function of neural circuits requires spatially and temporally balanced development of excitatory and inhibitory synapses. However, the molecular mechanisms coordinating excitatory and inhibitory synaptogenesis remain unknown. Here we demonstrate that SRGAP2A and its human-specific paralog SRGAP2C co-regulate the development of excitatory and inhibitory synapses in cortical pyramidal neurons in vivo. SRGAP2A promotes synaptic maturation, and ultimately the synaptic accumulation of AMPA and GABAA receptors, by interacting with key components of both excitatory and inhibitory postsynaptic scaffolds, Homer and Gephyrin. Furthermore, SRGAP2A limits the density of both types of synapses via its Rac1-GAP activity. SRGAP2C inhibits all identified functions of SRGAP2A, protracting the maturation and increasing the density of excitatory and inhibitory synapses. Our results uncover a molecular mechanism coordinating critical features of synaptic development and suggest that human-specific duplication of SRGAP2 might have contributed to the emergence of unique traits of human neurons while preserving the excitation/inhibition balance.
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100
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García-Nafría J, Watson JF, Greger IH. IVA cloning: A single-tube universal cloning system exploiting bacterial In Vivo Assembly. Sci Rep 2016; 6:27459. [PMID: 27264908 PMCID: PMC4893743 DOI: 10.1038/srep27459] [Citation(s) in RCA: 157] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/13/2016] [Indexed: 12/11/2022] Open
Abstract
In vivo homologous recombination holds the potential for optimal molecular cloning, however, current strategies require specialised bacterial strains or laborious protocols. Here, we exploit a recA-independent recombination pathway, present in widespread laboratory E.coli strains, to develop IVA (In Vivo Assembly) cloning. This system eliminates the need for enzymatic assembly and reduces all molecular cloning procedures to a single-tube, single-step PCR, performed in <2 hours from setup to transformation. Unlike other methods, IVA is a complete system, and offers significant advantages over alternative methods for all cloning procedures (insertions, deletions, site-directed mutagenesis and sub-cloning). Significantly, IVA allows unprecedented simplification of complex cloning procedures: five simultaneous modifications of any kind, multi-fragment assembly and library construction are performed in approximately half the time of current protocols, still in a single-step fashion. This system is efficient, seamless and sequence-independent, and requires no special kits, enzymes or proprietary bacteria, which will allow its immediate adoption by the academic and industrial molecular biology community.
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Affiliation(s)
- Javier García-Nafría
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Jake F. Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Ingo H. Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
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