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Dίaz E. Beyond the AMPA receptor: Diverse roles of SynDIG/PRRT brain-specific transmembrane proteins at excitatory synapses. Curr Opin Pharmacol 2021; 58:76-82. [PMID: 33964729 PMCID: PMC8195862 DOI: 10.1016/j.coph.2021.03.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 03/30/2021] [Indexed: 12/29/2022]
Abstract
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) are responsible for fast excitatory transmission in the brain. Deficits in synaptic transmission underlie a variety of neurological and psychiatric disorders. However, drugs that target AMPARs are challenging to develop, given the central role played in neurotransmission. Targeting AMPAR auxiliary factors offers an innovative approach for achieving specificity without altering baseline synaptic transmission. This review focuses on the SynDIG/proline-rich transmembrane protein (PRRT) family of AMPAR-associated transmembrane proteins. Although these factors are related based on sequence similarity, the proteins have evolved diverse actions at excitatory synapses that are not limited to the traditional role ascribed to an AMPAR auxiliary factor. SynDIG4/PRRT1 acts as a typical AMPAR auxiliary protein, while PRRT2 functions at presynaptic sites to regulate synaptic vesicle dynamics and is the causative gene for neurological paroxysmal disorders in humans. SynDIG/PRRT proteins are members of a larger superfamily that also include antiviral proteins known to restrict fusion between host and viral membranes and share some interesting characteristics.
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Affiliation(s)
- Elva Dίaz
- Department of Pharmacology, University of California Davis School of Medicine, 451 Health, Sciences Drive, Davis, CA 95616, USA.
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52
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Salm EJ, Dunn PJ, Shan L, Yamasaki M, Malewicz NM, Miyazaki T, Park J, Sumioka A, Hamer RRL, He WW, Morimoto-Tomita M, LaMotte RH, Tomita S. TMEM163 Regulates ATP-Gated P2X Receptor and Behavior. Cell Rep 2021; 31:107704. [PMID: 32492420 DOI: 10.1016/j.celrep.2020.107704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 04/14/2020] [Accepted: 05/06/2020] [Indexed: 12/18/2022] Open
Abstract
Fast purinergic signaling is mediated by ATP and ATP-gated ionotropic P2X receptors (P2XRs), and it is implicated in pain-related behaviors. The properties exhibited by P2XRs vary between those expressed in heterologous cells and in vivo. Several modulators of ligand-gated ion channels have recently been identified, suggesting that there are P2XR functional modulators in vivo. Here, we establish a genome-wide open reading frame (ORF) collection and perform functional screening to identify modulators of P2XR activity. We identify TMEM163, which specifically modulates the channel properties and pharmacology of P2XRs. We also find that TMEM163 is required for full function of the neuronal P2XR and a pain-related ATP-evoked behavior. These results establish TMEM163 as a critical modulator of P2XRs in vivo and a potential target for the discovery of drugs for treating pain.
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Affiliation(s)
- Elizabeth J Salm
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Patrick J Dunn
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Lili Shan
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Miwako Yamasaki
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Nathalie M Malewicz
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Taisuke Miyazaki
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Joongkyu Park
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Akio Sumioka
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | | | - Wei-Wu He
- OriGene Technologies, Inc., Rockville, MD 20850, USA
| | - Megumi Morimoto-Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Robert H LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06520, USA.
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53
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Kamalova A, Futai K, Delpire E, Nakagawa T. AMPA Receptor Auxiliary Subunit GSG1L Suppresses Short-Term Facilitation in Corticothalamic Synapses and Determines Seizure Susceptibility. Cell Rep 2021; 32:107921. [PMID: 32697982 PMCID: PMC7425083 DOI: 10.1016/j.celrep.2020.107921] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 05/06/2020] [Accepted: 06/26/2020] [Indexed: 01/29/2023] Open
Abstract
The anterior thalamus (AT) is critical for memory formation, processing navigational information, and seizure initiation. However, the molecular mechanisms that regulate synaptic function of AT neurons remain largely unexplored. We report that AMPA receptor auxiliary subunit GSG1L controls short-term plasticity in AT synapses that receive inputs from the cortex, but not in those receiving inputs from other pathways. A canonical auxiliary subunit stargazin co-exists in these neurons but is functionally absent from corticothalamic synapses. In GSG1L knockout mice, AT neurons exhibit hyperexcitability and the animals have increased susceptibility to seizures, consistent with a negative regulatory role of GSG1L. We hypothesize that negative regulation of synaptic function by GSG1L plays a critical role in maintaining optimal excitation in the AT. Kamalova et al. report the phenotypes of GSG1L KO mice. The synaptic function of AMPAR auxiliary subunit GSG1L in the anterior thalamus is input specific. GSG1L suppresses short-term facilitation and decreases AMPAR activity specifically in corticothalamic synapses, where stargazin is functionally absent. GSG1L KO mice exhibit hyperexcitability and seizure susceptibility.
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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
| | - Kensuke Futai
- Department of Neurobiology, Brudnick Neuropsychiatric Research Institute, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Eric Delpire
- 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; Department of Anesthesiology, 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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54
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Han TH, Vicidomini R, Ramos CI, Wang Q, Nguyen P, Jarnik M, Lee CH, Stawarski M, Hernandez RX, Macleod GT, Serpe M. Neto-α Controls Synapse Organization and Homeostasis at the Drosophila Neuromuscular Junction. Cell Rep 2021; 32:107866. [PMID: 32640231 PMCID: PMC7484471 DOI: 10.1016/j.celrep.2020.107866] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 02/27/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023] Open
Abstract
Glutamate receptor auxiliary proteins control receptor distribution and function, ultimately controlling synapse assembly, maturation, and plasticity. At the Drosophila neuromuscular junction (NMJ), a synapse with both pre- and postsynaptic kainate-type glutamate receptors (KARs), we show that the auxiliary protein Neto evolved functionally distinct isoforms to modulate synapse development and homeostasis. Using genetics, cell biology, and electrophysiology, we demonstrate that Neto-α functions on both sides of the NMJ. In muscle, Neto-α limits the size of the postsynaptic receptor field. In motor neurons (MNs), Neto-α controls neurotransmitter release in a KAR-dependent manner. In addition, Neto-α is both required and sufficient for the presynaptic increase in neurotransmitter release in response to reduced postsynaptic sensitivity. This KAR-independent function of Neto-α is involved in activity-induced cytomatrix remodeling. We propose that Drosophila ensures NMJ functionality by acquiring two Neto isoforms with differential expression patterns and activities.
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Affiliation(s)
- Tae Hee Han
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Rosario Vicidomini
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Cathy Isaura Ramos
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; Institute of Functional Genomics of Lyon, Lyon, France
| | - Qi Wang
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Peter Nguyen
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Michal Jarnik
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA
| | - Chi-Hon Lee
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA; Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Michal Stawarski
- Wilkes Honors College and Department of Biology, Florida Atlantic University, Jupiter, FL, USA; Biomedical Department, University of Basel, Basel, Switzerland
| | - Roberto X Hernandez
- Wilkes Honors College and Department of Biology, Florida Atlantic University, Jupiter, FL, USA
| | - Gregory T Macleod
- Wilkes Honors College and Department of Biology, Florida Atlantic University, Jupiter, FL, USA
| | - Mihaela Serpe
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD, USA.
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55
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Transcriptomic expression of AMPA receptor subunits and their auxiliary proteins in the human brain. Neurosci Lett 2021; 755:135938. [PMID: 33915226 DOI: 10.1016/j.neulet.2021.135938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 11/21/2022]
Abstract
Receptors to glutamate of the AMPA type (AMPARs) serve as the major gates of excitation in the human brain, where they participate in fundamental processes underlying perception, cognition and movement. Due to their central role in brain function, dysregulation of these receptors has been implicated in neuropathological states associated with a large variety of diseases that manifest with abnormal behaviors. The participation of functional abnormalities of AMPARs in brain disorders is strongly supported by genomic, transcriptomic and proteomic studies. Most of these studies have focused on the expression and function of the subunits that make up the channel and define AMPARs (GRIA1-GRIA4), as well of some accessory proteins. However, it is increasingly evident that native AMPARs are composed of a complex array of accessory proteins that regulate their trafficking, localization, kinetics and pharmacology, and a better understanding of the diversity and regional expression of these accessory proteins is largely needed. In this review we will provide an update on the state of current knowledge of AMPA receptors subunits in the context of their accessory proteins at the transcriptome level. We also summarize the regional expression in the human brain and its correlation with the channel forming subunits. Finally, we discuss some of the current limitations of transcriptomic analysis and propose potential ways to overcome them.
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56
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Auxiliary subunits of the AMPA receptor: The Shisa family of proteins. Curr Opin Pharmacol 2021; 58:52-61. [PMID: 33892364 DOI: 10.1016/j.coph.2021.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 03/01/2021] [Accepted: 03/01/2021] [Indexed: 11/15/2022]
Abstract
AMPA receptors mediate fast synaptic transmission in the CNS and can assemble with several types of auxiliary proteins in a spatio-temporal manner, from newly synthesized AMPA receptor tetramers to mature AMPA receptors in the cell membrane. As such, the interaction of auxiliary subunits with the AMPA receptor plays a major role in the regulation of AMPA receptor biogenesis, trafficking, and biophysical properties. Throughout the years, various 'families' of proteins have been identified and today the approximate full complement of AMPAR auxiliary proteins is known. This review presents the current knowledge on the most prominent AMPA-receptor-interacting auxiliary proteins, highlights recent results regarding the Shisa protein family, and provides a discussion on future research that might contribute to the discovery of novel pharmacological targets of auxiliary subunits.
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57
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Han W, Shepard RD, Lu W. Regulation of GABA ARs by Transmembrane Accessory Proteins. Trends Neurosci 2021; 44:152-165. [PMID: 33234346 PMCID: PMC7855156 DOI: 10.1016/j.tins.2020.10.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022]
Abstract
The vast majority of fast inhibitory transmission in the brain is mediated by GABA acting on GABAA receptors (GABAARs), which provides inhibitory balance to excitatory drive and controls neuronal output. GABAARs are also effectively targeted by clinically important drugs for treatment in a number of neurological disorders. It has long been hypothesized that function and pharmacology of GABAARs are determined by the channel pore-forming subunits. However, recent studies have provided new dimensions in studying GABAARs due to several transmembrane proteins that interact with GABAARs and modulate their trafficking and function. In this review, we summarize recent findings on these novel GABAAR transmembrane regulators and highlight a potential avenue to develop new GABAAR psychopharmacology by targeting these receptor-associated membrane proteins.
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Affiliation(s)
- Wenyan Han
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ryan D Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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58
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Rosenbaum MI, Clemmensen LS, Bredt DS, Bettler B, Strømgaard K. Targeting receptor complexes: a new dimension in drug discovery. Nat Rev Drug Discov 2020; 19:884-901. [PMID: 33177699 DOI: 10.1038/s41573-020-0086-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2020] [Indexed: 12/11/2022]
Abstract
Targeting receptor proteins, such as ligand-gated ion channels and G protein-coupled receptors, has directly enabled the discovery of most drugs developed to modulate receptor signalling. However, as the search for novel and improved drugs continues, an innovative approach - targeting receptor complexes - is emerging. Receptor complexes are composed of core receptor proteins and receptor-associated proteins, which have profound effects on the overall receptor structure, function and localization. Hence, targeting key protein-protein interactions within receptor complexes provides an opportunity to develop more selective drugs with fewer side effects. In this Review, we discuss our current understanding of ligand-gated ion channel and G protein-coupled receptor complexes and discuss strategies for their pharmacological modulation. Although such strategies are still in preclinical development for most receptor complexes, they exemplify how receptor complexes can be drugged, and lay the groundwork for this nascent area of research.
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Affiliation(s)
- Mette Ishøy Rosenbaum
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Louise S Clemmensen
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - David S Bredt
- Neuroscience Discovery, Janssen Pharmaceutical Companies of Johnson & Johnson, San Diego, CA, USA
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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59
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Glutamatergic Receptor Trafficking and Delivery: Role of the Exocyst Complex. Cells 2020; 9:cells9112402. [PMID: 33153008 PMCID: PMC7693776 DOI: 10.3390/cells9112402] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/21/2020] [Accepted: 10/23/2020] [Indexed: 12/29/2022] Open
Abstract
Cells comprise several intracellular membrane compartments that allow them to function properly. One of these functions is cargo movement, typically proteins and membranes within cells. These cargoes ride microtubules through vesicles from Golgi and recycling endosomes to the plasma membrane in order to be delivered and exocytosed. In neurons, synaptic functions employ this cargo trafficking to maintain inter-neuronal communication optimally. One of the complexes that oversee vesicle trafficking and tethering is the exocyst. The exocyst is a protein complex containing eight subunits first identified in yeast and then characterized in multicellular organisms. This complex is related to several cellular processes, including cellular growth, division, migration, and morphogenesis, among others. It has been associated with glutamatergic receptor trafficking and tethering into the synapse, providing the molecular machinery to deliver receptor-containing vesicles into the plasma membrane in a constitutive manner. In this review, we discuss the evidence so far published regarding receptor trafficking and the exocyst complex in both basal and stimulated levels, comparing constitutive trafficking and long-term potentiation-related trafficking.
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60
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Ramos-Vicente D, Bayés À. AMPA receptor auxiliary subunits emerged during early vertebrate evolution by neo/subfunctionalization of unrelated proteins. Open Biol 2020; 10:200234. [PMID: 33108974 PMCID: PMC7653359 DOI: 10.1098/rsob.200234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In mammalian synapses, the function of ionotropic glutamate receptors is critically modulated by auxiliary subunits. Most of these specifically regulate the synaptic localization and electrophysiological properties of AMPA-type glutamate receptors (AMPARs). Here, we comprehensively investigated the animal evolution of the protein families that contain AMPAR auxiliary subunits (ARASs). We observed that, on average, vertebrates have four times more ARASs than other animal species. We also demonstrated that ARASs belong to four unrelated protein families: CACNG-GSG1, cornichon, shisa and Dispanin C. Our study demonstrates that, despite the ancient origin of these four protein families, the majority of ARASs emerged during vertebrate evolution by independent but convergent processes of neo/subfunctionalization that resulted in the multiple ARASs found in present vertebrate genomes. Importantly, although AMPARs appeared and diversified in the ancestor of bilateral animals, the ARAS expansion did not occur until much later, in early vertebrate evolution. We propose that the surge in ARASs and consequent increase in AMPAR functionalities, contributed to the increased complexity of vertebrate brains and cognitive functions.
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Affiliation(s)
- David Ramos-Vicente
- Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau, Barcelona, Spain.,Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Àlex Bayés
- Molecular Physiology of the Synapse Laboratory, Biomedical Research Institute Sant Pau, Barcelona, Spain.,Universitat Autònoma de Barcelona, Barcelona, Spain
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61
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Devi SPS, Cheng Y, Tomita S, Howe JR, Zhang W. TARPs Modulate Receptor-Mediated Paired-Pulse Depression and Recovery from Desensitization. J Neurosci 2020; 40:8233-8247. [PMID: 32994336 PMCID: PMC7577600 DOI: 10.1523/jneurosci.3026-19.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 08/07/2020] [Accepted: 09/14/2020] [Indexed: 11/21/2022] Open
Abstract
Transmembrane AMPA receptor regulatory proteins (TARPs) are auxiliary AMPA receptor subunits that play a key role in receptor trafficking and in modulating receptor gating. The ability of TARPs to slow both deactivation and desensitization is isoform specific. However, TARP isoform-specific modulation of receptor properties remains uncharacterized. Here, we compare the isoform-specific effects of γ-2, γ-3, γ-4, and γ-8 TARPs on recovery from desensitization and responses to pairs of brief applications of glutamate. All four isoforms were able to reduce receptor-mediated paired-pulse depression and significantly speed recovery from desensitization in an isoform-specific manner. In the presence of TARPs, recovery time courses were observed to contain two components, fast and slow. The proportion of fast and slow components was determined by the TARP isoform. The time constant of recovery was also altered by the duration of glutamate application. When studies with TARP chimeras were performed, TARP extracellular loops were found to play a vital role in TARP modulation of recovery. Thus, isoform-specific differences in TARP modulation of recovery from desensitization influence receptor responses to repeated brief applications of glutamate, and these differences may impact frequency-dependent synaptic signaling in the mammalian central nervous system.SIGNIFICANCE STATEMENT AMPA receptors are major determinants of excitatory synaptic strength. The channel kinetics of AMPA receptors contribute to the kinetics of synaptic transmission. Transmembrane AMPA receptor regulatory proteins (TARPs) auxiliary subunits can modulate the decay kinetics of AMPA receptors. However, whether TARP isoforms specifically modulate receptor recovery is unclear. Here, we investigated the recovery kinetics of AMPA receptors by expressing various TARP isoforms and chimeras. We observed that the TARP isoforms and duration of glutamate application uniquely modulate time constants and the proportion of fast and slow components through a previously unidentified TARP domain. Given the impact of recovery kinetics on receptor responses to repetitive stimulation such as synaptic transmission, this work will be of great interest in the field of excitatory synaptic transmission research.
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Affiliation(s)
- Suma Priya Sudarsana Devi
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama 35233
| | - Yiru Cheng
- Department of Pharmacology of Chinese Materia Medica, Institution of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, Hebei Province 050017, China
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, Connecticut 06520
| | - James R Howe
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Wei Zhang
- Department of Pharmacology of Chinese Materia Medica, Institution of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, Hebei Province 050017, China
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62
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Wei M, Wang M, Wang J, Su F, Wang Y, Sun M, Wang S, Liu M, Wang H, Lu M, Li W, Gong Y, Yang L, Zhang C. PORCN Negatively Regulates AMPAR Function Independently of Subunit Composition and the Amino-Terminal and Carboxy-Terminal Domains of AMPARs. Front Cell Dev Biol 2020; 8:829. [PMID: 32984326 PMCID: PMC7477090 DOI: 10.3389/fcell.2020.00829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/04/2020] [Indexed: 11/13/2022] Open
Abstract
Most fast excitatory synaptic transmissions in the mammalian brain are mediated by α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs), which are ligand-gated cation channels. The membrane expression level of AMPARs is largely determined by auxiliary subunits in AMPAR macromolecules, including porcupine O-acyltransferase (PORCN), which negatively regulates AMPAR trafficking to the plasma membrane. However, whether PORCN-mediated regulation depends on AMPAR subunit composition or particular regions of a subunit has not been determined. We systematically examined the effects of PORCN on the ligand-gated current and surface expression level of GluA1, GluA2, and GluA3 AMPAR subunits, alone and in combination, as well as the PORCN-GluA interaction in heterologous HEK293T cells. PORCN inhibited glutamate-induced currents and the surface expression of investigated GluA AMPAR subunits in a subunit-independent manner. These inhibitory effects required neither the amino-terminal domain (ATD) nor the carboxy-terminal domain (CTD) of GluA subunits. In addition, PORCN interacted with AMPARs independently of their ATD or CTD. Thus, the functional inhibition of AMPARs by PORCN in transfected heterologous cells was independent of the ATD, CTD, and subunit composition of AMPARs.
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Affiliation(s)
- Mengping Wei
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Meng Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Jue Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Feng Su
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yangzhen Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Meng Sun
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Shanshan Wang
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Mengna Liu
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Hongyi Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Mingyang Lu
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Wei Li
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Yutian Gong
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Lei Yang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Chen Zhang
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
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63
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Schwenk J, Fakler B. Building of AMPA‐type glutamate receptors in the endoplasmic reticulum and its implication for excitatory neurotransmission. J Physiol 2020; 599:2639-2653. [DOI: 10.1113/jp279025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 07/21/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jochen Schwenk
- Institute of Physiology, Faculty of Medicine University of Freiburg Hermann‐Herder‐Str. 7 Freiburg 79104 Germany
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine University of Freiburg Hermann‐Herder‐Str. 7 Freiburg 79104 Germany
- Signalling Research Centres BIOSS and CIBSS Schänzlestr. 18 Freiburg 79104 Germany
- Center for Basics in NeuroModulation Breisacherstr. 4 Freiburg 79106 Germany
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64
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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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65
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Miguez-Cabello F, Sánchez-Fernández N, Yefimenko N, Gasull X, Gratacòs-Batlle E, Soto D. AMPAR/TARP stoichiometry differentially modulates channel properties. eLife 2020; 9:53946. [PMID: 32452760 PMCID: PMC7299370 DOI: 10.7554/elife.53946] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 05/24/2020] [Indexed: 11/15/2022] Open
Abstract
AMPARs control fast synaptic communication between neurons and their function relies on auxiliary subunits, which importantly modulate channel properties. Although it has been suggested that AMPARs can bind to TARPs with variable stoichiometry, little is known about the effect that this stoichiometry exerts on certain AMPAR properties. Here we have found that AMPARs show a clear stoichiometry-dependent modulation by the prototypical TARP γ2 although the receptor still needs to be fully saturated with γ2 to show some typical TARP-induced characteristics (i.e. an increase in channel conductance). We also uncovered important differences in the stoichiometric modulation between calcium-permeable and calcium-impermeable AMPARs. Moreover, in heteromeric AMPARs, γ2 positioning in the complex is important to exert certain TARP-dependent features. Finally, by comparing data from recombinant receptors with endogenous AMPAR currents from mouse cerebellar granule cells, we have determined a likely presence of two γ2 molecules at somatic receptors in this cell type.
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Affiliation(s)
- 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
| | - 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 Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, 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
| | - 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
| | - 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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66
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Ma L, Chen X, Zhao B, Shi Y, Han F. Enhanced apoptosis and decreased ampa receptors are involved in deficit in fear memory in rin1 knockout rats. J Affect Disord 2020; 268:173-182. [PMID: 32174475 DOI: 10.1016/j.jad.2020.02.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/20/2020] [Accepted: 02/26/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND Ras and Rab interactor 1 (Rin1) is predominantly expressed in memory-related brain regions, and has been reported to play an important role in fear memory. Increased expression of Rin1 in an animal model of posttraumatic stress disorder (PTSD) has been associated with enhanced acquisition of fear memories, but the exact mechanism of Rin1 in memory regulation are not clear. METHODS Here, we used Rin1-knockout rats to examine the effect of Rin1 on fear memories by fear conditional test and the molecular mechanisms that regulate these effects by immunofluorescence, western blotting and TUNEL. RESULTS Our results show that Rin1-knockout rats have a deficit in formation and extinction of Auditory fear memories. Lack of Rin1 results in enhanced apoptosis in the hippocampus through a pathway related to the mitochondria rather than the endoplasmic reticulum-related pathway. Importantly, the lack of Rin1 induces a decrease in α-amino-3‑hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR) found in the cytoplasm, but not in those found in the membrane. Expression of CaMKII (which is important for insertion of cytoplasmic AMPAR into the membrane) and stargazin (which is important for immobilization of AMPAR in the membrane) was not changed. The lack of Rin1 also induced changes in AMPAR distribution, from diffuse spread in the cells to clusters around the edge of the cell. Additionally, clustered AMPAR distribution showed a high degree of overlap with actin distribution. CONCLUSION These findings indicate that Rin1 affects not only apoptosis, but also the concentration and distribution pattern of AMPAR, which are important in the formation and extinction of fear memory.
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Affiliation(s)
- Linchuan Ma
- PTSD laboratory, Department of Histology and Embryology, Basic Medical College, China Medical University, Shenyang 110122, China.
| | - Xinzhao Chen
- PTSD laboratory, Department of Histology and Embryology, Basic Medical College, China Medical University, Shenyang 110122, China.
| | - Beiying Zhao
- PTSD laboratory, Department of Histology and Embryology, Basic Medical College, China Medical University, Shenyang 110122, China.
| | - Yuxiu Shi
- PTSD laboratory, Department of Histology and Embryology, Basic Medical College, China Medical University, Shenyang 110122, China
| | - Fang Han
- PTSD laboratory, Department of Histology and Embryology, Basic Medical College, China Medical University, Shenyang 110122, China.
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67
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Investigation of GluA1 and GluA2 AMPA receptor subtype distribution in the hippocampus and anterior cingulate cortex of Long Evans rats during development. IBRO Rep 2020; 8:91-100. [PMID: 32300670 PMCID: PMC7152689 DOI: 10.1016/j.ibror.2020.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 03/22/2020] [Indexed: 11/21/2022] Open
Abstract
Preadolescent development is characterized by a reorganization of connectivity within and between brain regions that coincides with the emergence of complex behaviors. During the preadolescent period, the rodent hippocampus and regions of the frontal cortex are remodelled as the brain strengthens active connections and eliminates others. In the developing and mature brain, changes in the properties of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAr)-mediated synaptic responses contribute to experience-dependent changes in neural organization and function. AMPAr are made up of 4 subunits, of which GluA1 and GluA2 have been shown to play the most prominent role in functional plasticity. In this study, we sought to determine whether levels of these two subunits changed during the course of pre-adolescent development in the hippocampus and anterior cingulate cortex (ACC). To investigate the developmental changes in GluA1 and GluA2 AMPAr subunits, Western blotting and immunohistochemistry were performed on the ACC and hippocampus from P18 - P30 and compared to adult (P50) levels and distribution. Within the hippocampus, protein levels of GluA1 and GluA2 peaked around P26-30 whereby localized staining in the dentate gyrus reflected this pattern. GluA1 and GluA2 levels within the ACC showed little variation during this developmental period. These results indicate that changes in AMPAr subunits within the hippocampus coincide with developmental modifications that underlie the shift from juvenile- to adult-like capabilities. However, changes in AMPAr distribution in the ACC might not mediate changes that reflect preadolescent developmental shifts.
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68
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Dolphin AC, Lee A. Presynaptic calcium channels: specialized control of synaptic neurotransmitter release. Nat Rev Neurosci 2020; 21:213-229. [PMID: 32161339 PMCID: PMC7873717 DOI: 10.1038/s41583-020-0278-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/12/2020] [Indexed: 11/09/2022]
Abstract
Chemical synapses are heterogeneous junctions formed between neurons that are specialized for the conversion of electrical impulses into the exocytotic release of neurotransmitters. Voltage-gated Ca2+ channels play a pivotal role in this process as they are the major conduits for the Ca2+ ions that trigger the fusion of neurotransmitter-containing vesicles with the presynaptic membrane. Alterations in the intrinsic function of these channels and their positioning within the active zone can profoundly alter the timing and strength of synaptic output. Advances in optical and electron microscopic imaging, structural biology and molecular techniques have facilitated recent breakthroughs in our understanding of the properties of voltage-gated Ca2+ channels that support their presynaptic functions. Here we examine the nature of these channels, how they are trafficked to and anchored within presynaptic boutons, and the mechanisms that allow them to function optimally in shaping the flow of information through neural circuits.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK.
| | - Amy Lee
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA, USA.
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69
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Yool AJ, Ramesh S. Molecular Targets for Combined Therapeutic Strategies to Limit Glioblastoma Cell Migration and Invasion. Front Pharmacol 2020; 11:358. [PMID: 32292341 PMCID: PMC7118801 DOI: 10.3389/fphar.2020.00358] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 03/10/2020] [Indexed: 12/21/2022] Open
Abstract
The highly invasive nature of glioblastoma imposes poor prospects for patient survival. Molecular evidence indicates glioblastoma cells undergo an intriguing expansion of phenotypic properties to include neuron-like signaling using excitable membrane ion channels and synaptic proteins, augmenting survival and motility. Neurotransmitter receptors, membrane signaling, excitatory receptors, and Ca2+ responses are important candidates for the design of customized treatments for cancers within the heterogeneous central nervous system. Relatively few published studies of glioblastoma multiforme (GBM) have evaluated pharmacological agents targeted to signaling pathways in limiting cancer cell motility. Transcriptomic analyses here identified classes of ion channels, ionotropic receptors, and synaptic proteins that are enriched in human glioblastoma biopsy samples. The pattern of GBM-enriched gene expression points to a major role for glutamate signaling. However, the predominant role of AMPA receptors in fast excitatory signaling throughout the central nervous system raises a challenge on how to target inhibitors selectively to cancer cells while maintaining tolerability. This review critically evaluates a panel of ligand- and voltage-gated ion channels and synaptic proteins upregulated in GBM, and the evidence for their potential roles in the pathological disease progress. Evidence suggests combinations of therapies could be more effective than single agents alone. Natural plant products used in traditional medicines for the treatment of glioblastoma contain flavonoids, terpenoids, polyphenols, epigallocatechin gallate, quinones, and saponins, which might serendipitously include agents that modulate some classes of signaling compounds highlighted in this review. New therapeutic strategies are likely to exploit evidence-based combinations of selected agents, each at a low dose, to create new cancer cell-specific therapeutics.
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Affiliation(s)
- Andrea J. Yool
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Sunita Ramesh
- Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
- College of Science and Engineering, Flinders University, Adelaide, SA, Australia
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70
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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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71
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Yu Q, Kumata K, Li H, Zhang Y, Chen Z, Zhang X, Shao T, Hatori A, Yamasaki T, Xie L, Hu K, Wang G, Josephson L, Sun S, Zhang MR, Liang SH. Synthesis and evaluation of 6-( 11C-methyl(4-(pyridin-2-yl)thiazol-2-yl)amino)benzo[d]thiazol-2(3H)-one for imaging γ-8 dependent transmembrane AMPA receptor regulatory protein by PET. Bioorg Med Chem Lett 2020; 30:126879. [PMID: 31879207 DOI: 10.1016/j.bmcl.2019.126879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 11/27/2019] [Accepted: 11/30/2019] [Indexed: 10/25/2022]
Abstract
Transmembrane AMPA receptor regulatory proteins (TARPs) are a recently discovered family of proteins that modulate AMPA receptors activity. Based on a potent and selective TARP subtype γ-8 antagonist, 6-(methyl(4-(pyridin-2-yl)thiazol-2-yl)amino)benzo[d]thiazol-2(3H)-one (compound 9), we perform the radiosynthesis of its 11C-isotopologue 1 and conduct preliminary PET evaluation to test the feasibility of imaging TARP γ-8 dependent receptors in vivo.
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Affiliation(s)
- Qingzhen Yu
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States
| | - Katsushi Kumata
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Hua Li
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States
| | - Yiding Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Zhen Chen
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States
| | - Xiaofei Zhang
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States
| | - Tuo Shao
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States
| | - Akiko Hatori
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Tomoteru Yamasaki
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Lin Xie
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Kuan Hu
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Gangqiang Wang
- Hubei Collaborative Innovation Centre for Non-power Nuclear Technology, College of Nuclear Technology & Chemistry and Biology, Hubei University of Science and Technology, Xianning 437100, PR China
| | - Lee Josephson
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States
| | - Shaofa Sun
- Hubei Collaborative Innovation Centre for Non-power Nuclear Technology, College of Nuclear Technology & Chemistry and Biology, Hubei University of Science and Technology, Xianning 437100, PR China.
| | - Ming-Rong Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan.
| | - Steven H Liang
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, United States.
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72
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Mastro TL, Preza A, Basu S, Chattarji S, Till SM, Kind PC, Kennedy MB. A sex difference in the response of the rodent postsynaptic density to synGAP haploinsufficiency. eLife 2020; 9:52656. [PMID: 31939740 PMCID: PMC6994236 DOI: 10.7554/elife.52656] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/14/2020] [Indexed: 11/17/2022] Open
Abstract
SynGAP is a postsynaptic density (PSD) protein that binds to PDZ domains of the scaffold protein PSD-95. We previously reported that heterozygous deletion of Syngap1 in mice is correlated with increased steady-state levels of other key PSD proteins that bind PSD-95, although the level of PSD-95 remains constant (Walkup et al., 2016). For example, the ratio to PSD-95 of Transmembrane AMPA-Receptor-associated Proteins (TARPs), which mediate binding of AMPA-type glutamate receptors to PSD-95, was increased in young Syngap1+/-mice. Here we show that only females and not males show a highly significant correlation between an increase in TARP and a decrease in synGAP in the PSDs of Syngap1+/-rodents. The data reveal a sex difference in the adaptation of the PSD scaffold to synGAP haploinsufficiency.
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Affiliation(s)
- Tara L Mastro
- Division of Biology and Biological Engineering, Caltech, Pasadena, United States
| | - Anthony Preza
- Division of Biology and Biological Engineering, Caltech, Pasadena, United States
| | - Shinjini Basu
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Sumantra Chattarji
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, Bangalore, India
| | - Sally M Till
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter C Kind
- Simons Initiative for the Developing Brain, Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.,Centre for Brain Development and Repair, Bangalore, India
| | - Mary B Kennedy
- Division of Biology and Biological Engineering, Caltech, Pasadena, United States
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73
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Morise J, Suzuki KGN, Kitagawa A, Wakazono Y, Takamiya K, Tsunoyama TA, Nemoto YL, Takematsu H, Kusumi A, Oka S. AMPA receptors in the synapse turnover by monomer diffusion. Nat Commun 2019; 10:5245. [PMID: 31748519 PMCID: PMC6868016 DOI: 10.1038/s41467-019-13229-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 10/28/2019] [Indexed: 12/27/2022] Open
Abstract
The number and subunit compositions of AMPA receptors (AMPARs), hetero- or homotetramers composed of four subunits GluA1–4, in the synapse is carefully tuned to sustain basic synaptic activity. This enables stimulation-induced synaptic plasticity, which is central to learning and memory. The AMPAR tetramers have been widely believed to be stable from their formation in the endoplasmic reticulum until their proteolytic decomposition. However, by observing GluA1 and GluA2 at the level of single molecules, we find that the homo- and heterotetramers are metastable, instantaneously falling apart into monomers, dimers, or trimers (in 100 and 200 ms, respectively), which readily form tetramers again. In the dendritic plasma membrane, GluA1 and GluA2 monomers and dimers are far more mobile than tetramers and enter and exit from the synaptic regions. We conclude that AMPAR turnover by lateral diffusion, essential for sustaining synaptic function, is largely done by monomers of AMPAR subunits, rather than preformed tetramers. The mechanisms regulating the turnover of the AMPARs in the synapse, which is critically important to sustain basic synaptic activity, remains unclear. In this study, authors used single-molecule imaging techniques to demonstrate that AMPAR tetramers are not stable entities and readily fall apart to dimers and monomers that could reform to tetramers at the synapse, and that rapidly diffusing monomers in the plasma membrane are primarily responsible for the AMPAR turnover in the synapse.
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Affiliation(s)
- Jyoji Morise
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Kenichi G N Suzuki
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, 501-1193, Japan. .,Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan.
| | - Ayaka Kitagawa
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Yoshihiko Wakazono
- Department of Integrative Physiology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Kogo Takamiya
- Department of Integrative Physiology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Taka A Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan
| | - Yuri L Nemoto
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan
| | - Hiromu Takematsu
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.,Department of Molecular Cell Biology, Faculty of Medical Technology, Graduate School of Health Sciences, Fujita Health University, Aichi, 470-1192, Japan
| | - Akihiro Kusumi
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan. .,Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan.
| | - Shogo Oka
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.
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74
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Linking Nanoscale Dynamics of AMPA Receptor Organization to Plasticity of Excitatory Synapses and Learning. J Neurosci 2019; 38:9318-9329. [PMID: 30381423 DOI: 10.1523/jneurosci.2119-18.2018] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/21/2018] [Accepted: 09/21/2018] [Indexed: 11/21/2022] Open
Abstract
The spatiotemporal organization of neurotransmitter receptors in the postsynaptic membrane is a fundamental determinant of synaptic transmission and thus of information processing by the brain. The ionotropic AMPA subtype of glutamate receptors (AMPARs) mediate fast excitatory synaptic transmission in the CNS. The number of AMPARs located en face presynaptic glutamate release sites sets the efficacy of synaptic transmission. Understanding how this number is set and regulated has been the topic of intense research in the last two decades. We showed that AMPARs are not stable in the synapse as initially thought. They continuously enter and exit the postsynaptic density by lateral diffusion, and they exchange between the neuronal surface and intracellular compartments by endocytosis and exocytosis at extrasynaptic sites. Regulation of these various trafficking pathways has emerged as a key mechanism for activity-dependent plasticity of synaptic transmission, a process important for learning and memory. I here present my view of these findings. In particular, the advent of super-resolution microscopy and single-molecule tracking has helped to uncover the intricacy of AMPARs' dynamic organization at the nanoscale. In addition, AMPAR surface diffusion is highly regulated by a variety of factors, including neuronal activity, stress hormones, and neurodegeneration, suggesting that AMPAR diffusion-trapping may play a central role in synapse function. Using innovative tools to understand further the link between receptor dynamics and synapse plasticity is now unveiling new molecular mechanisms of learning. Modifying AMPAR dynamics may emerge as a new target to correct synapse dysfunction in the diseased brain.
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75
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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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76
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Zeng M, Díaz-Alonso J, Ye F, Chen X, Xu J, Ji Z, Nicoll RA, Zhang M. Phase Separation-Mediated TARP/MAGUK Complex Condensation and AMPA Receptor Synaptic Transmission. Neuron 2019; 104:529-543.e6. [PMID: 31492534 DOI: 10.1016/j.neuron.2019.08.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 06/02/2019] [Accepted: 07/29/2019] [Indexed: 12/22/2022]
Abstract
Transmembrane AMPA receptor (AMPAR) regulatory proteins (TARPs) modulate AMPAR synaptic trafficking and transmission via disc-large (DLG) subfamily of membrane-associated guanylate kinases (MAGUKs). Despite extensive studies, the molecular mechanism governing specific TARP/MAGUK interaction remains elusive. Using stargazin and PSD-95 as the representatives, we discover that the entire tail of stargazin (Stg_CT) is required for binding to PSD-95. The PDZ binding motif (PBM) and an Arg-rich motif upstream of PBM conserved in TARPs bind to multiple sites on PSD-95, thus resulting in a highly specific and multivalent stargazin/PSD-95 complex. Stargazin in complex with PSD-95 or PSD-95-assembled postsynaptic complexes form highly concentrated and dynamic condensates via phase separation, reminiscent of stargazin/PSD-95-mediated AMPAR synaptic clustering and trapping. Importantly, charge neutralization mutations in TARP_CT Arg-rich motif weakened TARP's condensation with PSD-95 and impaired TARP-mediated AMPAR synaptic transmission in mice hippocampal neurons. The TARP_CT/PSD-95 interaction mode may have implications for understanding clustering of other synaptic transmembrane proteins.
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Affiliation(s)
- Menglong Zeng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Javier Díaz-Alonso
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Fei Ye
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xudong Chen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jia Xu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zeyang Ji
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Roger A Nicoll
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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77
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Diering GH, Huganir RL. The AMPA Receptor Code of Synaptic Plasticity. Neuron 2019; 100:314-329. [PMID: 30359599 DOI: 10.1016/j.neuron.2018.10.018] [Citation(s) in RCA: 491] [Impact Index Per Article: 98.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 01/02/2023]
Abstract
Changes in the properties and postsynaptic abundance of AMPA-type glutamate receptors (AMPARs) are major mechanisms underlying various forms of synaptic plasticity, including long-term potentiation (LTP), long-term depression (LTD), and homeostatic scaling. The function and the trafficking of AMPARs to and from synapses is modulated by specific AMPAR GluA1-GluA4 subunits, subunit-specific protein interactors, auxiliary subunits, and posttranslational modifications. Layers of regulation are added to AMPAR tetramers through these different interactions and modifications, increasing the computational power of synapses. Here we review the reliance of synaptic plasticity on AMPAR variants and propose "the AMPAR code" as a conceptual framework. The AMPAR code suggests that AMPAR variants will be predictive of the types and extent of synaptic plasticity that can occur and that a hierarchy exists such that certain AMPARs will be disproportionally recruited to synapses during LTP/homeostatic scaling up, or removed during LTD/homeostatic scaling down.
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Affiliation(s)
- Graham H Diering
- Department of Cell Biology and Physiology, and Neuroscience Center, University of North Carolina, Chapel Hill, NC 27514, USA
| | - Richard L Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21205, USA.
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78
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Witkin JM, Ping X, Cerne R, Mouser C, Jin X, Hobbs J, Tiruveedhula VVNPB, Li G, Jahan R, Rashid F, Kumar Golani L, Cook JM, Smith JL. The value of human epileptic tissue in the characterization and development of novel antiepileptic drugs: The example of CERC-611 and KRM-II-81. Brain Res 2019; 1722:146356. [PMID: 31369732 DOI: 10.1016/j.brainres.2019.146356] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 07/17/2019] [Accepted: 07/29/2019] [Indexed: 12/25/2022]
Abstract
The need for improved antiepileptics is clearly mandated despite the existence of multiple existing medicines from different chemical and mechanistic classes. Standard of care agents do not fully control epilepsies and have a variety of side-effect and safety issues. Patients typically take multiple antiepileptic drugs and yet many continue to have seizures. Antiepileptic-unresponsive seizures are life-disrupting and life-threatening. One approach to seizure control is surgical resection of affected brain tissue and associated neural circuits. Although non-human brain studies can provide insight into novel antiepileptic mechanisms, human epileptic brain is the bottom-line biological substrate. Human epileptic brain can provide definitive information on the presence or absence of the putative protein targets of interest in the patient population, the potential changes in these proteins in the epileptic state, and the engagement of novel molecules and their functional impact in target tissue. In this review, we discuss data on two novel potential antiepileptic drugs. CERC-611 (LY3130481) is an AMPA receptor antagonist that selectively blocks AMPA receptors associated with the auxiliary protein TARP γ-8 and is in clinical development. KRM-II-81 is a positive allosteric modulator of GABAA receptors selectively associated with protein subunits α2 and α 3. Preclinical data on these compounds argue that patient-based biological data increase the probability that a newly discovered molecule will translate its antiepileptic potential to patients.
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Affiliation(s)
- Jeffrey M Witkin
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA; Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
| | - Xingjie Ping
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Rok Cerne
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Claire Mouser
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Jon Hobbs
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | | | - Guanguan Li
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Rajwana Jahan
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Farjana Rashid
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Lalit Kumar Golani
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - James M Cook
- Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, St. Vincent's Hospital, Indianapolis, IN, USA.
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79
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Wang XT, Cai XY, Xu FX, Zhou L, Zheng R, Ma KY, Xu ZH, Shen Y. MEA6 Deficiency Impairs Cerebellar Development and Motor Performance by Tethering Protein Trafficking. Front Cell Neurosci 2019; 13:250. [PMID: 31244610 PMCID: PMC6580151 DOI: 10.3389/fncel.2019.00250] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 05/20/2019] [Indexed: 11/13/2022] Open
Abstract
Meningioma expressed antigen 6 (MEA6), also called cutaneous T cell lymphoma-associated antigen 5 (cTAGE5), was initially found in tumor tissues. MEA6 is located in endoplasmic reticulum (ER) exit sites and regulates the transport of collagen, very low density lipoprotein, and insulin. It is also reported that MEA6 might be related to Fahr's syndrome, which comprises neurological, movement, and neuropsychiatric disorders. Here, we show that MEA6 is critical to cerebellar development and motor performance. Mice with conditional knockout of MEA6 (Nestin-Cre;MEA6F/F) display smaller sizes of body and brain compared to control animals, and survive maximal 28 days after birth. Immunohistochemical and behavioral studies demonstrate that these mutant mice have defects in cerebellar development and motor performance. In contrast, PC deletion of MEA6 (pCP2-Cre;MEA6F/F) causes milder phenotypes in cerebellar morphology and motor behaviors. While pCP2-Cre;MEA6F/F mice have normal lobular formation and gait, they present the extensive self-crossing of PC dendrites and damaged motor learning. Interestingly, the expression of key molecules that participates in cerebellar development, including Slit2 and brain derived neurotrophic factor (BDNF), is significantly increased in ER, suggesting that MEA6 ablation impairs ER function and thus these proteins are arrested in ER. Our study provides insight into the roles of MEA6 in the brain and the pathogenesis of Fahr's syndrome.
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Affiliation(s)
- Xin-Tai Wang
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Xin-Yu Cai
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Fang-Xiao Xu
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Lin Zhou
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Rui Zheng
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Kuang-Yi Ma
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhi-Heng Xu
- State Key Laboratory of Molecular Developmental Biology, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Genetics and Developmental Biology Chinese Academy of Sciences, Beijing, China
| | - Ying Shen
- Department of Neurobiology, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
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80
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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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81
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Abstract
Cerebral organoids are an emerging cutting-edge technology to model human brain
development and neurodevelopmental disorders, for which mouse models exhibit significant
limitations. In the human brain, synaptic connections define neural circuits, and synaptic
deficits account for various neurodevelopmental disorders. Thus, harnessing the full power
of cerebral organoids for human brain modeling requires the ability to visualize and
analyze synapses in cerebral organoids. Previously, we devised an optimized method to
generate human cerebral organoids, and showed that optimal organoids express mature-neuron
markers, including synaptic proteins and neurotransmitter receptors and transporters.
Here, we give evidence for synaptogenesis in cerebral organoids, via microscopical
visualization of synapses. We also describe multiple approaches to quantitatively analyze
synapses in cerebral organoids. Collectively, our work provides sufficient evidence for
the possibility of modeling synaptogenesis and synaptic disorders in cerebral organoids,
and may help advance the use of cerebral organoids in molecular neuroscience and studies
of neurodevelopmental disorders such as autism.
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Affiliation(s)
- Abraam M Yakoub
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Mark Sadek
- Department of Pharmaceutical Biotechnology, University of Illinois College of Pharmacy, Chicago, IL, USA.,Department of Research and Development, Akorn Pharmaceuticals, Vernon Hills, IL, USA
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82
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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: 61] [Impact Index Per Article: 12.2] [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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83
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Herguedas B, Watson JF, Ho H, Cais O, García-Nafría J, Greger IH. Architecture of the heteromeric GluA1/2 AMPA receptor in complex with the auxiliary subunit TARP γ8. Science 2019; 364:science.aav9011. [PMID: 30872532 PMCID: PMC6513756 DOI: 10.1126/science.aav9011] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 03/04/2019] [Indexed: 11/02/2022]
Abstract
AMPA-type glutamate receptors (AMPARs) mediate excitatory neurotransmission and are central regulators of synaptic plasticity, a molecular mechanism underlying learning and memory. Although AMPARs act predominantly as heteromers, structural studies have focused on homomeric assemblies. Here, we present a cryo-electron microscopy structure of the heteromeric GluA1/2 receptor associated with two transmembrane AMPAR regulatory protein (TARP) γ8 auxiliary subunits, the principal AMPAR complex at hippocampal synapses. Within the receptor, the core subunits arrange to give the GluA2 subunit dominant control of gating. This structure reveals the geometry of the Q/R site that controls calcium flux, suggests association of TARP-stabilized lipids, and demonstrates that the extracellular loop of γ8 modulates gating by selectively interacting with the GluA2 ligand-binding domain. Collectively, this structure provides a blueprint for deciphering the signal transduction mechanisms of synaptic AMPARs.
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Affiliation(s)
- Beatriz Herguedas
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK.
| | - Jake F Watson
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
| | - Hinze Ho
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
| | - Ondrej Cais
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
| | | | - Ingo H Greger
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK.
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84
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Knopp KL, Simmons RMA, Guo W, Adams BL, Gardinier KM, Gernert DL, Ornstein PL, Porter W, Reel J, Ding C, Wang H, Qian Y, Burris KD, Need A, Barth V, Swanson S, Catlow J, Witkin JM, Zwart R, Sher E, Choong KC, Wall TM, Schober D, Felder CC, Kato AS, Bredt DS, Nisenbaum ES. Modulation of TARP γ8–Containing AMPA Receptors as a Novel Therapeutic Approach for Chronic Pain. J Pharmacol Exp Ther 2019; 369:345-363. [DOI: 10.1124/jpet.118.250126] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 03/06/2019] [Indexed: 12/30/2022] Open
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85
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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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86
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Identification of Zebrafish Calcium Toolkit Genes and their Expression in the Brain. Genes (Basel) 2019; 10:genes10030230. [PMID: 30889933 PMCID: PMC6471419 DOI: 10.3390/genes10030230] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 03/13/2019] [Indexed: 01/12/2023] Open
Abstract
Zebrafish are well-suited for in vivo calcium imaging because of the transparency of their larvae and the ability to express calcium probes in various cell subtypes. This model organism has been used extensively to study brain development, neuronal function, and network activity. However, only a few studies have investigated calcium homeostasis and signaling in zebrafish neurons, and little is known about the proteins that are involved in these processes. Using bioinformatics analysis and available databases, the present study identified 491 genes of the zebrafish Calcium Toolkit (CaTK). Using RNA-sequencing, we then evaluated the expression of these genes in the adult zebrafish brain and found 380 hits that belonged to the CaTK. Based on quantitative real-time polymerase chain reaction arrays, we estimated the relative mRNA levels in the brain of CaTK genes at two developmental stages. In both 5 dpf larvae and adult zebrafish, the highest relative expression was observed for tmbim4, which encodes a Golgi membrane protein. The present data on CaTK genes will contribute to future applications of zebrafish as a model for in vivo and in vitro studies of Ca2+ signaling.
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87
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Luan C, Ye Y, Singh T, Barghouth M, Eliasson L, Artner I, Zhang E, Renström E. The calcium channel subunit gamma-4 is regulated by MafA and necessary for pancreatic beta-cell specification. Commun Biol 2019; 2:106. [PMID: 30911681 PMCID: PMC6420573 DOI: 10.1038/s42003-019-0351-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 02/08/2019] [Indexed: 12/22/2022] Open
Abstract
Voltage-gated Ca2+ (CaV) channels trigger glucose-induced insulin secretion in pancreatic beta-cell and their dysfunction increases diabetes risk. These heteromeric complexes include the main subunit alpha1, and the accessory ones, including subunit gamma that remains unexplored. Here, we demonstrate that CaV gamma subunit 4 (CaVγ4) is downregulated in islets from human donors with diabetes, diabetic Goto-Kakizaki (GK) rats, as well as under conditions of gluco-/lipotoxic stress. Reduction of CaVγ4 expression results in decreased expression of L-type CaV1.2 and CaV1.3, thereby suppressing voltage-gated Ca2+ entry and glucose stimulated insulin exocytosis. The most important finding is that CaVγ4 expression is controlled by the transcription factor responsible for beta-cell specification, MafA, as verified by chromatin immunoprecipitation and experiments in beta-cell specific MafA knockout mice (MafA Δβcell ). Taken together, these findings suggest that CaVγ4 is necessary for maintaining a functional differentiated beta-cell phenotype. Treatment aiming at restoring CaVγ4 may help to restore beta-cell function in diabetes.
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Affiliation(s)
- Cheng Luan
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, 202 13 Malmö, Sweden
| | - Yingying Ye
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, 202 13 Malmö, Sweden
| | - Tania Singh
- Stem Cell Center, Department of Laboratory Medicine, Lund University, 221 85 Lund, Sweden
| | - Mohammad Barghouth
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, 202 13 Malmö, Sweden
| | - Lena Eliasson
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, 202 13 Malmö, Sweden
| | - Isabella Artner
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, 202 13 Malmö, Sweden
- Stem Cell Center, Department of Laboratory Medicine, Lund University, 221 85 Lund, Sweden
| | - Enming Zhang
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, 202 13 Malmö, Sweden
| | - Erik Renström
- Lund University Diabetes Center, Department of Clinical Sciences Malmö, Lund University, 202 13 Malmö, Sweden
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88
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Savall BM, Wu D, Swanson DM, Seierstad M, Wu N, Vives Martinez J, García Olmos B, Lord B, Coe K, Koudriakova T, Lovenberg TW, Carruthers NI, Maher MP, Ameriks MK. Discovery of Imidazo[1,2- a]pyrazines and Pyrazolo[1,5- c]pyrimidines as TARP γ-8 Selective AMPAR Negative Modulators. ACS Med Chem Lett 2019; 10:267-272. [PMID: 30891124 DOI: 10.1021/acsmedchemlett.8b00599] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 12/26/2018] [Indexed: 11/29/2022] Open
Abstract
This report discloses the discovery and characterization of imidazo[1,2-a]pyrazines and pyrazolo[1,5-c]pyrimidines as selective negative modulators of α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptors (AMPARs) associated with transmembrane AMPAR regulatory protein γ-8. Imidazopyrazine 5 was initially identified as a promising γ-8 selective high-throughput screening hit, and subsequent structure-activity relationship optimization yielded subnanomolar, brain penetrant leads. Replacement of the imidazopyrazine core with an isosteric pyrazolopyrimidine scaffold improved microsomal stability and efflux liabilities to provide 26, JNJ-61432059. Following oral administration, 26 exhibited time- and dose-dependent AMPAR/γ-8 receptor occupancy in mouse hippocampus, which resulted in robust seizure protection in corneal kindling and pentylenetetrazole (PTZ) anticonvulsant models.
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Affiliation(s)
- Brad M. Savall
- Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, California 92037, United States
| | - Dongpei Wu
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Devin M. Swanson
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Mark Seierstad
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Nyantsz Wu
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Jorge Vives Martinez
- Eurofins-Villapharma Research S.L., Parque Tecnológico de Fuente Alamo, Carretera El Estrecho-Lobosilo, Km. 2,5, E-30320 Fuente Alamo (Murcia), Spain
| | - Beatriz García Olmos
- Eurofins-Villapharma Research S.L., Parque Tecnológico de Fuente Alamo, Carretera El Estrecho-Lobosilo, Km. 2,5, E-30320 Fuente Alamo (Murcia), Spain
| | - Brian Lord
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Kevin Coe
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Tatiana Koudriakova
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Timothy W. Lovenberg
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Nicholas I. Carruthers
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Michael P. Maher
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
| | - Michael K. Ameriks
- Janssen Research & Development L.L.C., 3210 Merryfield Row, San Diego, California 92121 United States
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89
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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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90
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Stewart M, Lau P, Banks G, Bains RS, Castroflorio E, Oliver PL, Dixon CL, Kruer MC, Kullmann DM, Acevedo-Arozena A, Wells SE, Corrochano S, Nolan PM. Loss of Frrs1l disrupts synaptic AMPA receptor function, and results in neurodevelopmental, motor, cognitive and electrographical abnormalities. Dis Model Mech 2019; 12:dmm.036806. [PMID: 30692144 PMCID: PMC6398485 DOI: 10.1242/dmm.036806] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/16/2019] [Indexed: 01/09/2023] Open
Abstract
Loss-of-function mutations in a human AMPA receptor-associated protein, ferric chelate reductase 1-like (FRRS1L), are associated with a devastating neurological condition incorporating choreoathetosis, cognitive deficits and epileptic encephalopathies. Furthermore, evidence from overexpression and ex vivo studies has implicated FRRS1L in AMPA receptor biogenesis, suggesting that changes in glutamatergic signalling might underlie the disorder. Here, we investigated the neurological and neurobehavioural correlates of the disorder using a mouse Frrs1l null mutant. The study revealed several neurological defects that mirrored those seen in human patients. We established that mice lacking Frrs1l suffered from a broad spectrum of early-onset motor deficits with no progressive, age-related deterioration. Moreover, Frrs1l−/− mice were hyperactive, irrespective of test environment, exhibited working memory deficits and displayed significant sleep fragmentation. Longitudinal electroencephalographic (EEG) recordings also revealed abnormal EEG results in Frrs1l−/− mice. Parallel investigations into disease aetiology identified a specific deficiency in AMPA receptor levels in the brain of Frrs1l−/− mice, while the general levels of several other synaptic components remained unchanged, with no obvious alterations in the number of synapses. Furthermore, we established that Frrsl1 deletion results in an increased proportion of immature AMPA receptors, indicated by incomplete glycosylation of GLUA2 (also known as GRIA2) and GLUA4 (also known as GRIA4) AMPA receptor proteins. This incomplete maturation leads to cytoplasmic retention and a reduction of those specific AMPA receptor levels in the postsynaptic membrane. Overall, this study determines, for the first time in vivo, how loss of FRRS1L function can affect glutamatergic signalling, and provides mechanistic insight into the development and progression of a human hyperkinetic disorder. This article has an associated First Person interview with the first author of the paper. Summary: Loss of the epilepsy-related gene Frrs1l in mice causes a dramatic reduction in AMPA receptor levels at the synapse, eliciting severe motor and coordination disabilities, hyperactivity and cognitive defects, with some evidence of behavioural seizures.
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Affiliation(s)
| | - Petrina Lau
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | - Gareth Banks
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | | | | | - Peter L Oliver
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | - Christine L Dixon
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Michael C Kruer
- Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85013, USA
| | - Dimitri M Kullmann
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Abraham Acevedo-Arozena
- Unidad de Investigación Hospital Universitario de Canarias, La Laguna 38320, Spain.,ITB, Universidad de La Laguna, La Laguna 38320, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), La Laguna 38320, Spain
| | - Sara E Wells
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | | | - Patrick M Nolan
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
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91
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Calcium Channel Subunit α2δ4 Is Regulated by Early Growth Response 1 and Facilitates Epileptogenesis. J Neurosci 2019; 39:3175-3187. [PMID: 30792272 DOI: 10.1523/jneurosci.1731-18.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 12/03/2018] [Accepted: 01/08/2019] [Indexed: 12/17/2022] Open
Abstract
Transient brain insults, including status epilepticus (SE), can trigger a period of epileptogenesis during which functional and structural reorganization of neuronal networks occurs resulting in the onset of focal epileptic seizures. In recent years, mechanisms that regulate the dynamic transcription of individual genes during epileptogenesis and thereby contribute to the development of a hyperexcitable neuronal network have been elucidated. Our own results have shown early growth response 1 (Egr1) to transiently increase expression of the T-type voltage-dependent Ca2+ channel (VDCC) subunit CaV3.2, a key proepileptogenic protein. However, epileptogenesis involves complex and dynamic transcriptomic alterations; and so far, our understanding of the transcriptional control mechanism of gene regulatory networks that act in the same processes is limited. Here, we have analyzed whether Egr1 acts as a key transcriptional regulator for genes contributing to the development of hyperexcitability during epileptogenesis. We found Egr1 to drive the expression of the VDCC subunit α2δ4, which was augmented early and persistently after pilocarpine-induced SE. Furthermore, we show that increasing levels of α2δ4 in the CA1 region of the hippocampus elevate seizure susceptibility of mice by slightly decreasing local network activity. Interestingly, we also detected increased expression levels of Egr1 and α2δ4 in human hippocampal biopsies obtained from epilepsy surgery. In conclusion, Egr1 controls the abundance of the VDCC subunits CaV3.2 and α2δ4, which act synergistically in epileptogenesis, and thereby contributes to a seizure-induced "transcriptional Ca2+ channelopathy."SIGNIFICANCE STATEMENT The onset of focal recurrent seizures often occurs after an epileptogenic process induced by transient insults to the brain. Recently, transcriptional control mechanisms for individual genes involved in converting neurons hyperexcitable have been identified, including early growth response 1 (Egr1), which activates transcription of the T-type Ca2+ channel subunit CaV3.2. Here, we find Egr1 to regulate also the expression of the voltage-dependent Ca2+ channel subunit α2δ4, which was augmented after pilocarpine- and kainic acid-induced status epilepticus. In addition, we observed that α2δ4 affected spontaneous network activity and the susceptibility for seizure induction. Furthermore, we detected corresponding dynamics in human biopsies from epilepsy patients. In conclusion, Egr1 orchestrates a seizure-induced "transcriptional Ca2+ channelopathy" consisting of CaV3.2 and α2δ4, which act synergistically in epileptogenesis.
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92
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Tomita S. Molecular constituents and localization of the ionotropic GABA receptor complex in vivo. Curr Opin Neurobiol 2019; 57:81-86. [PMID: 30784980 DOI: 10.1016/j.conb.2019.01.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 01/14/2019] [Indexed: 01/24/2023]
Abstract
The ionotropic GABA receptor (GABAAR) mediates fast inhibition in the brain. The GABAAR pore-forming (α, β, and non-α/β) subunits were isolated approximately 30 years ago and have since been the focus of extensive studies. As a result, many properties of GABAARs, including subunit assembly and channel and pharmacological properties, have been discovered. However, several of the underlying mechanisms such as the process for the synaptic localization of GABAARs remain unsolved. A reinvestigation of native GABAAR complexes in the brain and primary neurons identified two major molecular constituents, namely, the transmembrane GARLH/LHFPL protein family and the inhibitory synaptic protein neuroligin 2. This identification of the principal components of native receptor complexes may provide new mechanistic insight on receptor regulation.
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Affiliation(s)
- Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, United States.
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93
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Fu H, Chen Z, Josephson L, Li Z, Liang SH. Positron Emission Tomography (PET) Ligand Development for Ionotropic Glutamate Receptors: Challenges and Opportunities for Radiotracer Targeting N-Methyl-d-aspartate (NMDA), α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA), and Kainate Receptors. J Med Chem 2019; 62:403-419. [PMID: 30110164 PMCID: PMC6393217 DOI: 10.1021/acs.jmedchem.8b00714] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) mediate excitatory neurotransmission within the mammalian central nervous system. iGluRs exist as three main groups: N-methyl-d-aspartate receptors (NMDARs), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), and kainate receptors. The past decades have witnessed a remarkable development of PET tracers targeting different iGluRs including NMDARs and AMPARs, and several of the tracers have advanced to clinical imaging studies. Here, we assess the recent development of iGluR PET probes, focusing on tracer design, brain kinetics, and performance in PET imaging studies. Furthermore, this review will not only present challenges in the tracer development but also provide novel approaches in conjunction with most recent drug discovery efforts on these iGluRs, including subtype-selective NMDAR and transmembrane AMPAR regulatory protein modulators and positive allosteric modulators (PAMs) of AMPARs. These approaches, if successful as PET tracers, may provide fundamental knowledge to understand the roles of iGluR receptors under physiological and pathological conditions.
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Affiliation(s)
- Hualong Fu
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
| | - Zijing Li
- State Key Laboratory of Molecular Vaccinology, Molecular Diagnosis & Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen 361102, P. R. China
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114 USA
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94
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Cortical expression of AMPA receptors during postnatal development in a genetic model of absence epilepsy. Int J Dev Neurosci 2018; 73:19-25. [PMID: 30593850 DOI: 10.1016/j.ijdevneu.2018.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 11/25/2018] [Accepted: 12/25/2018] [Indexed: 11/23/2022] Open
Abstract
Childhood absence epilepsy has been associated with poor academic performance, behavioural difficulties, as well as increased risk of physical injury in some affected children. The frequent episodes of 'absence' arise from corticothalamocortical network dysfunction, with multifactorial mechanisms potentially involved in genetically different patients. Aberrations in glutamatergic neurotransmission has been implicated in some seizure models, and we have recently reported that reduced cortical AMPA receptor (AMPAR) expression (predominantly GluA4- containing AMPARs) in parvalbumin-containing (PV+) inhibitory interneurons, could underlie seizure generation in the stargazer mutant mouse. In the present study, we investigate AMPA receptor subunit changes occurring during postnatal development in the stargazer mouse, to determine when these changes occur relative to seizure onset and thus could be contributory to seizure generation. Using quantitative western blotting, we analysed the expression of AMPAR GluA1-4 subunits in the somatosensory cortex at three critical time points; two before seizure onset (postnatal days (PN) 7-9 and 13-15), and one at seizure onset (PN17-18) in stargazers. We report that compared to their non-epileptic littermates, in the stargazer somatosensory cortex, there was a significant reduction in expression of AMPARs containing GluA1, 3 and 4 subunits prior to seizure onset, whereas reduction in expression of GluA2-AMPARs appears to be a post-seizure event. Thus, while loss of GluA4-containing AMPARs (likely GluA1/4 and GluA3/4) may be linked to seizure induction, the loss of GluA2-containing AMPARs is a secondary post-seizure mechanism, which is most likely involved in seizure maintenance.
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95
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Zwart R, Mazzo F, Sher E. Microtransplantation of human brain receptors into oocytes to tackle key questions in drug discovery. Drug Discov Today 2018; 24:533-543. [PMID: 30395928 DOI: 10.1016/j.drudis.2018.10.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/18/2018] [Accepted: 10/30/2018] [Indexed: 10/27/2022]
Abstract
It is important in drug discovery to demonstrate that activity of novel drugs found by screening on recombinant receptors translates to activity on native human receptors in brain areas affected by disease. In this review, we summarise the development and use of the microtransplantation technique. Native receptors are reconstituted from human brain tissues into oocytes from the frog Xenopus laevis where they can be functionally assessed. Oocytes microtransplanted with hippocampal tissue from an epileptic patient were used to demonstrate that new antiepileptic agents act on receptors in diseased tissue. Furthermore, frozen post-mortem human tissues were used to show that drugs are active on receptors in brain areas associated with a disease; but not in areas associated with side effects.
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Affiliation(s)
- Ruud Zwart
- Eli Lilly, Lilly Research Centre, Erl Wood Manor, Sunninghill Road, Windlesham, GU20 6PH, UK.
| | - Francesca Mazzo
- Eli Lilly, Lilly Research Centre, Erl Wood Manor, Sunninghill Road, Windlesham, GU20 6PH, UK
| | - Emanuele Sher
- Eli Lilly, Lilly Research Centre, Erl Wood Manor, Sunninghill Road, Windlesham, GU20 6PH, UK
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96
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Hiester BG, Becker MI, Bowen AB, Schwartz SL, Kennedy MJ. Mechanisms and Role of Dendritic Membrane Trafficking for Long-Term Potentiation. Front Cell Neurosci 2018; 12:391. [PMID: 30425622 PMCID: PMC6218485 DOI: 10.3389/fncel.2018.00391] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/11/2018] [Indexed: 01/19/2023] Open
Abstract
Long-term potentiation (LTP) of excitatory synapses is a major form of plasticity for learning and memory in the central nervous system. While the molecular mechanisms of LTP have been debated for decades, there is consensus that LTP induction activates membrane trafficking pathways within dendrites that are essential for synapse growth and strengthening. Current models suggest that key molecules for synaptic potentiation are sequestered within intracellular organelles, which are mobilized by synaptic activity to fuse with the plasma membrane following LTP induction. While the identity of the factors mobilized to the plasma membrane during LTP remain obscure, the field has narrowly focused on AMPA-type glutamate receptors. Here, we review recent literature and present new experimental data from our lab investigating whether AMPA receptors trafficked from intracellular organelles directly contribute to synaptic strengthening during LTP. We propose a modified model where membrane trafficking delivers distinct factors that are required to maintain synapse growth and AMPA receptor incorporation following LTP. Finally, we pose several fundamental questions that may guide further inquiry into the role of membrane trafficking for synaptic plasticity.
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Affiliation(s)
- Brian G Hiester
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Matthew I Becker
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, United States
| | - Aaron B Bowen
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Samantha L Schwartz
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Matthew J Kennedy
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
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97
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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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98
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Bialer M, Johannessen SI, Koepp MJ, Levy RH, Perucca E, Tomson T, White HS. Progress report on new antiepileptic drugs: A summary of the Fourteenth Eilat Conference on New Antiepileptic Drugs and Devices (EILAT XIV). I. Drugs in preclinical and early clinical development. Epilepsia 2018; 59:1811-1841. [DOI: 10.1111/epi.14557] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 08/08/2018] [Accepted: 08/08/2018] [Indexed: 01/06/2023]
Affiliation(s)
- Meir Bialer
- Faculty of Medicine; School of Pharmacy and David R. Bloom Center for Pharmacy; Institute for Drug Research; Hebrew University of Jerusalem; Jerusalem Israel
| | - Svein I. Johannessen
- National Center for Epilepsy; Sandvika Norway
- Department of Pharmacology; Oslo University Hospital; Oslo Norway
| | - Matthias J. Koepp
- Department of Clinical and Experimental Epilepsy; UCL Institute of Neurology; London UK
| | - René H. Levy
- Departments of Pharmaceutics and Neurological Surgery; University of Washington; Seattle Washington
| | - Emilio Perucca
- Department of Internal Medicine and Therapeutics; University of Pavia; Pavia Italy
- IRCCS Mondino Foundation; Pavia Italy
| | - Torbjörn Tomson
- Department of Clinical Neuroscience; Karolinska Institute; Stockholm Sweden
| | - H. Steve White
- Department of Pharmacy; School of Pharmacy; University of Washington; Seattle Washington
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99
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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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100
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Abstract
This review will first describe the importance of Ca2+ entry for function of excitable cells, and the subsequent discovery of voltage-activated calcium conductances in these cells. This finding was rapidly followed by the identification of multiple subtypes of calcium conductance in different tissues. These were initially termed low- and high-voltage activated currents, but were then further subdivided into L-, N-, PQ-, R- and T-type calcium currents on the basis of differing pharmacology, voltage-dependent and kinetic properties, and single channel conductance. Purification of skeletal muscle calcium channels allowed the molecular identification of the pore-forming and auxiliary α2δ, β and ϒ subunits present in these calcium channel complexes. These advances then led to the cloning of the different subunits, which permitted molecular characterisation, to match the cloned channels with physiological function. Studies with knockout and other mutant mice then allowed further investigation of physiological and pathophysiological roles of calcium channels. In terms of pharmacology, cardiovascular L-type channels are targets for the widely used antihypertensive 1,4-dihydropyridines and other calcium channel blockers, N-type channels are a drug target in pain, and α2δ-1 is the therapeutic target of the gabapentinoid drugs, used in neuropathic pain. Recent structural advances have allowed a deeper understanding of Ca2+ permeation through the channel pore and the structure of both the pore-forming and auxiliary subunits. Voltage-gated calcium channels are subject to multiple pathways of modulation by G-protein and second messenger regulation. Furthermore, their trafficking pathways, subcellular localisation and functional specificity are the subjects of active investigation.
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