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Zhang D, Lape R, Shaikh SA, Kohegyi BK, Watson JF, Cais O, Nakagawa T, Greger IH. Modulatory mechanisms of TARP γ8-selective AMPA receptor therapeutics. Nat Commun 2023; 14:1659. [PMID: 36966141 PMCID: PMC10039940 DOI: 10.1038/s41467-023-37259-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 03/09/2023] [Indexed: 03/27/2023] Open
Abstract
AMPA glutamate receptors (AMPARs) mediate excitatory neurotransmission throughout the brain. Their signalling is uniquely diversified by brain region-specific auxiliary subunits, providing an opportunity for the development of selective therapeutics. AMPARs associated with TARP γ8 are enriched in the hippocampus, and are targets of emerging anti-epileptic drugs. To understand their therapeutic activity, we determined cryo-EM structures of the GluA1/2-γ8 receptor associated with three potent, chemically diverse ligands. We find that despite sharing a lipid-exposed and water-accessible binding pocket, drug action is differentially affected by binding-site mutants. Together with patch-clamp recordings and MD simulations we also demonstrate that ligand-triggered reorganisation of the AMPAR-TARP interface contributes to modulation. Unexpectedly, one ligand (JNJ-61432059) acts bifunctionally, negatively affecting GluA1 but exerting positive modulatory action on GluA2-containing AMPARs, in a TARP stoichiometry-dependent manner. These results further illuminate the action of TARPs, demonstrate the sensitive balance between positive and negative modulatory action, and provide a mechanistic platform for development of both positive and negative selective AMPAR modulators.
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Affiliation(s)
- Danyang Zhang
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Remigijus Lape
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Saher A Shaikh
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Bianka K Kohegyi
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Jake F Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
- IST Austria, Klosterneuburg, Austria
| | - Ondrej Cais
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, USA
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
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2
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Herguedas B, Kohegyi BK, Dohrke JN, Watson JF, Zhang D, Ho H, Shaikh SA, Lape R, Krieger JM, Greger IH. Mechanisms underlying TARP modulation of the GluA1/2-γ8 AMPA receptor. Nat Commun 2022; 13:734. [PMID: 35136046 PMCID: PMC8826358 DOI: 10.1038/s41467-022-28404-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 01/13/2022] [Indexed: 01/01/2023] Open
Abstract
AMPA-type glutamate receptors (AMPARs) mediate rapid signal transmission at excitatory synapses in the brain. Glutamate binding to the receptor’s ligand-binding domains (LBDs) leads to ion channel activation and desensitization. Gating kinetics shape synaptic transmission and are strongly modulated by transmembrane AMPAR regulatory proteins (TARPs) through currently incompletely resolved mechanisms. Here, electron cryo-microscopy structures of the GluA1/2 TARP-γ8 complex, in both open and desensitized states (at 3.5 Å), reveal state-selective engagement of the LBDs by the large TARP-γ8 loop (‘β1’), elucidating how this TARP stabilizes specific gating states. We further show how TARPs alter channel rectification, by interacting with the pore helix of the selectivity filter. Lastly, we reveal that the Q/R-editing site couples the channel constriction at the filter entrance to the gate, and forms the major cation binding site in the conduction path. Our results provide a mechanistic framework of how TARPs modulate AMPAR gating and conductance. AMPA glutamate receptors, mediate the majority of excitatory signaling in the brain. Here the authors show how the auxiliary subunit TARP-γ8 shapes gating kinetics, ion conductance and rectification properties of the heteromeric GluA1/2 AMPA receptor.
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Affiliation(s)
- Beatriz Herguedas
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK.,Institute for Biocomputation and Physics of Complex Systems (BIFI) and Laboratorio de Microscopías Avanzadas (LMA), University of Zaragoza, 50018, Zaragoza, Spain
| | - Bianka K Kohegyi
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Jan-Niklas Dohrke
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK.,Universitätsmedizin Göttingen, Georg-August-Universität, 37075, Göttingen, Germany
| | - Jake F Watson
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK.,Institute of Science and Technology (IST) Austria, Am Campus 1, 3400, Klosterneuburg, Austria
| | - Danyang Zhang
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Hinze Ho
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK.,Department of Physiology, Development and Neuroscience, University of Cambridge, Physiological Laboratory, Cambridge, UK
| | - Saher A Shaikh
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Remigijus Lape
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK
| | - James M Krieger
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Ingo H Greger
- Neurobiology Division MRC Laboratory of Molecular Biology, Cambridge, UK.
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3
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Witkin JM. The romantic age of pharmacological science. Pharmacol Biochem Behav 2022; 214:173354. [DOI: 10.1016/j.pbb.2022.173354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 11/25/2022]
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Martin EE, Wleklinski E, Hoang HTM, Ahmad M. Interaction and Subcellular Association of PRRT1/SynDIG4 With AMPA Receptors. Front Synaptic Neurosci 2021; 13:705664. [PMID: 34408636 PMCID: PMC8365426 DOI: 10.3389/fnsyn.2021.705664] [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: 05/05/2021] [Accepted: 07/05/2021] [Indexed: 11/13/2022] Open
Abstract
AMPA receptors (AMPAR) are organized into supramolecular complexes in association with other membrane proteins that provide exquisite regulation of their biophysical properties and subcellular trafficking. Proline-rich transmembrane protein 1 (PRRT1), also named as SynDIG4, is a component of native AMPAR complexes in multiple brain regions. Deletion of PRRT1 leads to altered surface levels and phosphorylation status of AMPARs, as well as impaired forms of synaptic plasticity. Here, we have investigated the mechanisms underlying the observed regulation of AMPARs by investigating the interaction properties and subcellular localization of PRRT1. Our results show that PRRT1 can interact physically with all AMPAR subunits GluA1-GluA4. We decipher the membrane topology of PRRT1 to find that contrary to the predicted dual membrane pass, only the second hydrophobic segment spans the membrane completely, and is involved in mediating the interaction with AMPARs. We also report a physical interaction of PRRT1 with phosphatase PP2B that dephosphorylates AMPARs during synaptic plasticity. Our co-localization analysis in primary neuronal cultures identifies that PRRT1 associates with AMPARs extrasynaptically where it localizes to early and recycling endosomes as well as to the plasma membrane. These findings advance the understanding of the mechanisms by which PRRT1 regulates AMPARs under basal conditions and during synaptic plasticity.
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Affiliation(s)
- Emily Eischen Martin
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Erica Wleklinski
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Hanh T M Hoang
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Mohiuddin Ahmad
- Department of Cell Biology, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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Cull‐Candy SG, Farrant M. Ca 2+ -permeable AMPA receptors and their auxiliary subunits in synaptic plasticity and disease. J Physiol 2021; 599:2655-2671. [PMID: 33533533 PMCID: PMC8436767 DOI: 10.1113/jp279029] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 01/28/2021] [Indexed: 12/14/2022] Open
Abstract
AMPA receptors are tetrameric glutamate-gated ion channels that mediate a majority of fast excitatory neurotransmission in the brain. They exist as calcium-impermeable (CI-) and calcium-permeable (CP-) subtypes, the latter of which lacks the GluA2 subunit. CP-AMPARs display an array of distinctive biophysical and pharmacological properties that allow them to be functionally identified. This has revealed that they play crucial roles in diverse forms of central synaptic plasticity. Here we summarise the functional hallmarks of CP-AMPARs and describe how these are modified by the presence of auxiliary subunits that have emerged as pivotal regulators of AMPARs. A lasting change in the prevalence of GluA2-containing AMPARs, and hence in the fraction of CP-AMPARs, is a feature in many maladaptive forms of synaptic plasticity and neurological disorders. These include modifications of glutamatergic transmission induced by inflammatory pain, fear conditioning, cocaine exposure, and anoxia-induced damage in neurons and glia. Furthermore, defective RNA editing of GluA2 can cause altered expression of CP-AMPARs and is implicated in motor neuron damage (amyotrophic lateral sclerosis) and the proliferation of cells in malignant gliomas. A number of the players involved in CP-AMPAR regulation have been identified, providing useful insight into interventions that may prevent the aberrant CP-AMPAR expression. Furthermore, recent molecular and pharmacological developments, particularly the discovery of TARP subtype-selective drugs, offer the exciting potential to modify some of the harmful effects of increased CP-AMPAR prevalence in a brain region-specific manner.
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Affiliation(s)
- Stuart G. Cull‐Candy
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonGower StreetLondonWC1E 6BTUK
| | - Mark Farrant
- Department of Neuroscience, Physiology and PharmacologyUniversity College LondonGower StreetLondonWC1E 6BTUK
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Takahashi Y, Terada T, Muto Y. Systems Level Analysis and Identification of Pathways and Key Genes Associated with Delirium. Genes (Basel) 2020; 11:genes11101225. [PMID: 33086708 PMCID: PMC7590056 DOI: 10.3390/genes11101225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/15/2020] [Accepted: 10/16/2020] [Indexed: 11/16/2022] Open
Abstract
Delirium is a complex pathophysiological process, and multiple contributing mechanisms have been identified. However, it is largely unclear how the genes associated with delirium contribute and which of them play key roles. In this study, the genes associated with delirium were retrieved from the Comparative Toxicogenomics Database (CTD) and integrated through a protein-protein interaction (PPI) network. Delirium-associated genes formed a highly interconnected PPI subnetwork, indicating a high tendency to interact and agglomerate. Using the Molecular Complex Detection (MCODE) algorithm, we identified the top two delirium-relevant network modules, M1 and M5, that have the most significant enrichments for the delirium-related gene sets. Functional enrichment analysis showed that genes related to neurotransmitter receptor activity were enriched in both modules. Moreover, analyses with genes located in human accelerated regions (HARs) provided evidence that HAR-Brain genes were overrepresented in the delirium-relevant network modules. We found that four of the HAR-Brain genes, namely APP, PLCB1, NPY, and HTR2A, in the M1 module were highly connected and appeared to exhibit hub properties, which might play vital roles in delirium development. Further understanding of the function of the identified modules and member genes could help to identify therapeutic intervention targets and diagnostic biomarkers for delirium.
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Affiliation(s)
- Yukiko Takahashi
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, 1-1, Yanagido, Gifu 501-1194, Japan; (Y.T.); (T.T.)
- Department of Adult Nursing (Acute phase), Gifu University School of Medicine, 1-1, Yanagido, Gifu 501-1193, Japan
| | - Tomoyoshi Terada
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, 1-1, Yanagido, Gifu 501-1194, Japan; (Y.T.); (T.T.)
- Department of Functional Bioscience, Gifu University School of Medicine, 1-1, Yanagido, Gifu 501-1193, Japan
| | - Yoshinori Muto
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, 1-1, Yanagido, Gifu 501-1194, Japan; (Y.T.); (T.T.)
- Department of Functional Bioscience, Gifu University School of Medicine, 1-1, Yanagido, Gifu 501-1193, Japan
- Correspondence: ; Tel.: +81-58-293-3241
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Dohrke JN, Watson JF, Birchall K, Greger IH. Characterizing the binding and function of TARP γ8-selective AMPA receptor modulators. J Biol Chem 2020; 295:14565-14577. [PMID: 32747446 PMCID: PMC7586208 DOI: 10.1074/jbc.ra120.014135] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/31/2020] [Indexed: 12/21/2022] Open
Abstract
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid(AMPA)-type glutamate receptors (AMPARs) are the predominant excitatory neurotransmitter receptors in the brain, where they mediate synaptic transmission and plasticity. Excessive AMPAR activation leads to diseases such as epilepsy. AMPAR properties are modulated by auxiliary proteins and foremost by the transmembrane AMPAR regulatory proteins (TARPs). These distribute in unique expression patterns across the brain, rendering AMPAR/TARP complexes promising targets for region-specific therapeutic intervention. TARP γ8 is predominantly expressed in the forebrain and is enriched in the hippocampus, a region associated with temporal lobe epilepsy. Recent high-throughput medicinal chemistry screens have identified multiple promising compounds that selectively target AMPARs associated with γ8 and hold promise for epilepsy treatment. However, how these modulators target the receptor complex is currently unknown. Here, we use a combination of ligand docking, molecular dynamics simulations, and electrophysiology to address this question. We identify a conserved oxindole isostere, shared between three structurally diverse modulators (LY-3130481, JNJ-55511118, and JNJ-61432059) as the major module engaging γ8 by an H-bond to Asn-172 (γ8). The remaining variable region of each molecule likely targets the receptor complex in ligand-selective modes. Functional data reveal parallels in the underlying modulatory action of two prominent compounds. This work will aid development of refined AMPAR epilepsy therapeutics and facilitate to uncover the mechanisms by which TARPs modulate the receptor.
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Affiliation(s)
- Jan-Niklas Dohrke
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Jake F Watson
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - Ingo H Greger
- Neurobiology Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom.
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Fritzius T, Bettler B. The organizing principle of GABA B receptor complexes: Physiological and pharmacological implications. Basic Clin Pharmacol Toxicol 2019; 126 Suppl 6:25-34. [PMID: 31033219 PMCID: PMC7317483 DOI: 10.1111/bcpt.13241] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 04/15/2019] [Indexed: 12/19/2022]
Abstract
GABAB receptors (GBRs), the G protein-coupled receptors for the neurotransmitter γ-aminobutyric acid (GABA), regulate synaptic transmission at most synapses in the brain. Proteomic approaches revealed that native GBR complexes assemble from an inventory of ~30 proteins that provide a molecular basis for the functional diversity observed with these receptors. Studies with reconstituted GBR complexes in heterologous cells and complementary knockout studies have allowed to identify cellular and physiological functions for obligate and several non-obligate receptor components. It emerges that modular association of receptor components in space and time generates a variety of multiprotein receptor complexes with different localizations, kinetic properties and effector channels. This article summarizes current knowledge on the organizing principle of GBR complexes. We further discuss unanticipated receptor functions, links to disease and opportunities for drug discovery arising from the identification of novel receptor components.
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Affiliation(s)
- Thorsten Fritzius
- Department of Biomedicine, Institute of Physiology, University of Basel, Basel, Switzerland
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, University of Basel, Basel, Switzerland
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