1
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Perozzo AM, Schwenk J, Kamalova A, Nakagawa T, Fakler B, Bowie D. GSG1L-containing AMPA receptor complexes are defined by their spatiotemporal expression, native interactome and allosteric sites. Nat Commun 2023; 14:6799. [PMID: 37884493 PMCID: PMC10603098 DOI: 10.1038/s41467-023-42517-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023] Open
Abstract
Transmembrane AMPA receptor regulatory proteins (TARPs) and germ cell-specific gene 1-like protein (GSG1L) are claudin-type AMPA receptor (AMPAR) auxiliary subunits that profoundly regulate glutamatergic synapse strength and plasticity. While AMPAR-TARP complexes have been extensively studied, less is known about GSG1L-containing AMPARs. Here, we show that GSG1L's spatiotemporal expression, native interactome and allosteric sites are distinct. GSG1L generally expresses late during brain development in a region-specific manner, constituting about 5% of all AMPAR complexes in adulthood. While GSG1L can co-assemble with TARPs or cornichons (CNIHs), it also assembles as the sole auxiliary subunit. Unexpectedly, GSG1L acts through two discrete evolutionarily-conserved sites on the agonist-binding domain with a weak allosteric interaction at the TARP/KGK site to slow desensitization, and a stronger interaction at a different site that slows recovery from desensitization. Together, these distinctions help explain GSG1L's evolutionary past and how it fulfills a unique signaling role within glutamatergic synapses.
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Affiliation(s)
- Amanda M Perozzo
- Integrated Program in Neuroscience, McGill University, Montreal, QC, H3A 1A1, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, H3G 1Y6, Canada
| | - Jochen Schwenk
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
| | - Aichurok Kamalova
- Department of Molecular Physiology and Biophysics, Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, 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
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
- Signaling Research Centers BIOSS and CIBSS, University of Freiburg, Schänzlestr. 18, 79104, Freiburg, Germany
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, H3G 1Y6, Canada.
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2
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Ravi AS, Zeng M, Chen X, Sandoval G, Diaz-Alonso J, Zhang M, Nicoll RA. Long-term potentiation reconstituted with an artificial TARP/PSD-95 complex. Cell Rep 2022; 41:111483. [PMID: 36223737 PMCID: PMC9797105 DOI: 10.1016/j.celrep.2022.111483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 07/08/2022] [Accepted: 09/19/2022] [Indexed: 12/30/2022] Open
Abstract
The critical role of AMPA receptor (AMPAR) trafficking in long-term potentiation (LTP) of excitatory synaptic transmission is now well established, but the underlying molecular mechanism is still uncertain. Recent research suggests that PSD-95 captures AMPARs via an interaction with the AMPAR auxiliary subunits-transmembrane AMPAR regulatory proteins (TARPs). To determine if such interaction is a core minimal component of the AMPAR trafficking and LTP mechanism, we engineered artificial binding partners, which individually were biochemically and functionally dead but which, when expressed together, rescue binding and both basal synaptic transmission and LTP. These findings establish the TARP/PSD-95 complex as an essential interaction underlying AMPAR trafficking and LTP.
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Affiliation(s)
- Anagh Sinha Ravi
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, CA, USA
| | - Menglong Zeng
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xudong Chen
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Gerardo Sandoval
- Department of Anatomy and Neurobiology, University of California at Irvine, Irvine, CA, USA,Center for the Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA, USA
| | - Javier Diaz-Alonso
- Department of Anatomy and Neurobiology, University of California at Irvine, Irvine, CA, USA,Center for the Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA, USA,Correspondence: (J.D.-A.), (R.A.N.)
| | - Mingjie Zhang
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China,Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518036, China,School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Roger A. Nicoll
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, CA, USA,Lead contact,Correspondence: (J.D.-A.), (R.A.N.)
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3
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Watson JF, Pinggera A, Ho H, Greger IH. AMPA receptor anchoring at CA1 synapses is determined by N-terminal domain and TARP γ8 interactions. Nat Commun 2021; 12:5083. [PMID: 34426577 PMCID: PMC8382838 DOI: 10.1038/s41467-021-25281-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/02/2021] [Indexed: 12/30/2022] Open
Abstract
AMPA receptor (AMPAR) abundance and positioning at excitatory synapses regulates the strength of transmission. Changes in AMPAR localisation can enact synaptic plasticity, allowing long-term information storage, and is therefore tightly controlled. Multiple mechanisms regulating AMPAR synaptic anchoring have been described, but with limited coherence or comparison between reports, our understanding of this process is unclear. Here, combining synaptic recordings from mouse hippocampal slices and super-resolution imaging in dissociated cultures, we compare the contributions of three AMPAR interaction domains controlling transmission at hippocampal CA1 synapses. We show that the AMPAR C-termini play only a modulatory role, whereas the extracellular N-terminal domain (NTD) and PDZ interactions of the auxiliary subunit TARP γ8 are both crucial, and each is sufficient to maintain transmission. Our data support a model in which γ8 accumulates AMPARs at the postsynaptic density, where the NTD further tunes their positioning. This interplay between cytosolic (TARP γ8) and synaptic cleft (NTD) interactions provides versatility to regulate synaptic transmission and plasticity.
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Affiliation(s)
- Jake F Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
- IST Austria, Am Campus 1, Klosterneuburg, Austria
| | - Alexandra Pinggera
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
| | - Hinze Ho
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom.
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4
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Bissen D, Foss F, Acker-Palmer A. AMPA receptors and their minions: auxiliary proteins in AMPA receptor trafficking. Cell Mol Life Sci 2019; 76:2133-2169. [PMID: 30937469 PMCID: PMC6502786 DOI: 10.1007/s00018-019-03068-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/12/2019] [Accepted: 03/07/2019] [Indexed: 12/12/2022]
Abstract
To correctly transfer information, neuronal networks need to continuously adjust their synaptic strength to extrinsic stimuli. This ability, termed synaptic plasticity, is at the heart of their function and is, thus, tightly regulated. In glutamatergic neurons, synaptic strength is controlled by the number and function of AMPA receptors at the postsynapse, which mediate most of the fast excitatory transmission in the central nervous system. Their trafficking to, at, and from the synapse, is, therefore, a key mechanism underlying synaptic plasticity. Intensive research over the last 20 years has revealed the increasing importance of interacting proteins, which accompany AMPA receptors throughout their lifetime and help to refine the temporal and spatial modulation of their trafficking and function. In this review, we discuss the current knowledge about the roles of key partners in regulating AMPA receptor trafficking and focus especially on the movement between the intracellular, extrasynaptic, and synaptic pools. We examine their involvement not only in basal synaptic function, but also in Hebbian and homeostatic plasticity. Included in our review are well-established AMPA receptor interactants such as GRIP1 and PICK1, the classical auxiliary subunits TARP and CNIH, and the newest additions to AMPA receptor native complexes.
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Affiliation(s)
- Diane Bissen
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
- Max Planck Institute for Brain Research, Max von Laue Str. 4, 60438, Frankfurt am Main, Germany
| | - Franziska Foss
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
| | - Amparo Acker-Palmer
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.
- Max Planck Institute for Brain Research, Max von Laue Str. 4, 60438, Frankfurt am Main, Germany.
- Cardio-Pulmonary Institute (CPI), Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.
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5
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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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Corney BPA, Widnall CL, Rees DJ, Davies JS, Crunelli V, Carter DA. Regulatory Architecture of the Neuronal Cacng2/Tarpγ2 Gene Promoter: Multiple Repressive Domains, a Polymorphic Regulatory Short Tandem Repeat, and Bidirectional Organization with Co-regulated lncRNAs. J Mol Neurosci 2018; 67:282-294. [PMID: 30478755 PMCID: PMC6373327 DOI: 10.1007/s12031-018-1208-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 11/08/2018] [Indexed: 12/14/2022]
Abstract
CACNG2 (TARPγ2, Stargazin) is a multi-functional regulator of excitatory neurotransmission and has been implicated in the pathological processes of several brain diseases. Cacng2 function is dependent upon expression level, but currently, little is known about the molecular mechanisms that control expression of this gene. To address this deficit and investigate disease-related gene variants, we have cloned and characterized the rat Cacng2 promoter and have defined three major features: (i) multiple repressive domains that include an array of RE-1 silencing transcription factor (REST) elements, and a calcium regulatory element-binding factor (CaRF) element, (ii) a (poly-GA) short tandem repeat (STR), and (iii) bidirectional organization with expressed lncRNAs. Functional activity of the promoter was demonstrated in transfected neuronal cell lines (HT22 and PC12), but although selective removal of REST and CaRF domains was shown to enhance promoter-driven transcription, the enhanced Cacng2 promoter constructs were still about fivefold weaker than a comparable rat Synapsin-1 promoter sequence. Direct evidence of REST activity at the Cacng2 promoter was obtained through co-transfection with an established dominant-negative REST (DNR) construct. Investigation of the GA-repeat STR revealed polymorphism across both animal strains and species, and size variation was also observed in absence epilepsy disease model cohorts (Genetic Absence Epilepsy Rats, Strasbourg [GAERS] and non-epileptic control [NEC] rats). These data provide evidence of a genotype (STR)-phenotype correlation that may be unique with respect to proximal gene regulatory sequence in the demonstrated absence of other promoter, or 3' UTR variants in GAERS rats. However, although transcriptional regulatory activity of the STR was demonstrated in further transfection studies, we did not find a GAERS vs. NEC difference, indicating that this specific STR length variation may only be relevant in the context of other (Cacna1h and Kcnk9) gene variants in this disease model. Additional studies revealed further (bidirectional) complexity at the Cacng2 promoter, and we identified novel, co-regulated, antisense rat lncRNAs that are paired with Cacng2 mRNA. These studies have provided novel insights into the organization of a synaptic protein gene promoter, describing multiple repressive and modulatory domains that can mediate diverse regulatory inputs.
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Affiliation(s)
- B P A Corney
- School of Biosciences, Cardiff University, CF103AX, Cardiff, UK
| | - C L Widnall
- School of Biosciences, Cardiff University, CF103AX, Cardiff, UK
| | - D J Rees
- Molecular Neurobiology, Institute of Life Science, Swansea University, Swansea, SA2 8PP, UK
| | - J S Davies
- Molecular Neurobiology, Institute of Life Science, Swansea University, Swansea, SA2 8PP, UK
| | - V Crunelli
- School of Biosciences, Cardiff University, CF103AX, Cardiff, UK
| | - D A Carter
- School of Biosciences, Cardiff University, CF103AX, Cardiff, UK.
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7
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LTP requires postsynaptic PDZ-domain interactions with glutamate receptor/auxiliary protein complexes. Proc Natl Acad Sci U S A 2018; 115:3948-3953. [PMID: 29581259 DOI: 10.1073/pnas.1800719115] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Long-term potentiation (LTP) is a persistent strengthening of synaptic transmission in the brain and is arguably the most compelling cellular and molecular model for learning and memory. Previous work found that both AMPA receptors and exogenously expressed kainate receptors are equally capable of expressing LTP, despite their limited homology and their association with distinct auxiliary subunits, indicating that LTP is far more promiscuous than previously thought. What might these two subtypes of glutamate receptor have in common? Using a single-cell molecular replacement strategy, we demonstrate that the AMPA receptor auxiliary subunit TARP γ-8, via its PDZ-binding motif, is indispensable for both basal synaptic transmission and LTP. Remarkably, kainate receptors and their auxiliary subunits Neto proteins share the same requirement of PDZ-binding domains for synaptic trafficking and LTP. Together, these results suggest that a minimal postsynaptic requirement for LTP is the PDZ binding of glutamate receptors/auxiliary subunits to PSD scaffolding proteins.
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8
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CKAMP44 modulates integration of visual inputs in the lateral geniculate nucleus. Nat Commun 2018; 9:261. [PMID: 29343769 PMCID: PMC5772470 DOI: 10.1038/s41467-017-02415-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 11/25/2017] [Indexed: 11/08/2022] Open
Abstract
Relay neurons in the dorsal lateral geniculate nucleus (dLGN) receive excitatory inputs from retinal ganglion cells (RGCs). Retinogeniculate synapses are characterized by a prominent short-term depression of AMPA receptor (AMPAR)-mediated currents, but the underlying mechanisms and its function for visual integration are not known. Here we identify CKAMP44 as a crucial auxiliary subunit of AMPARs in dLGN relay neurons, where it increases AMPAR-mediated current amplitudes and modulates gating of AMPARs. Importantly, CKAMP44 is responsible for the distinctive short-term depression in retinogeniculate synapses by reducing the rate of recovery from desensitization of AMPARs. Genetic deletion of CKAMP44 strongly reduces synaptic short-term depression, which leads to increased spike probability of relay neurons when activated with high-frequency inputs from retinogeniculate synapses. Finally, in vivo recordings reveal augmented ON- and OFF-responses of dLGN neurons in CKAMP44 knockout (CKAMP44−/−) mice, demonstrating the importance of CKAMP44 for modulating synaptic short-term depression and visual input integration. The function of receptor desensitization in vivo is not well understood. Here, the authors show that deletion of CKAMP44, an AMPAR auxiliary protein that modulates desensitization of AMPAR currents, affects synaptic facilitation at retinogeniculate synapses and visually-evoked firing in awake mice.
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9
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Lee MR, Gardinier KM, Gernert DL, Schober DA, Wright RA, Wang H, Qian Y, Witkin JM, Nisenbaum ES, Kato AS. Structural Determinants of the γ-8 TARP Dependent AMPA Receptor Antagonist. ACS Chem Neurosci 2017; 8:2631-2647. [PMID: 28825787 DOI: 10.1021/acschemneuro.7b00186] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The forebrain specific AMPA receptor antagonist, LY3130481/CERC-611, which selectively antagonizes the AMPA receptors associated with TARP γ-8, an auxiliary subunit enriched in the forebrain, has potent antiepileptic activities without motor side effects. We designated the compounds with such activities as γ-8 TARP dependent AMPA receptor antagonists (γ-8 TDAAs). In this work, we further investigated the mechanisms of action using a radiolabeled γ-8 TDAA and ternary structural modeling with mutational validations to characterize the LY3130481 binding to γ-8. The radioligand binding to the cells heterologously expressing GluA1 and/or γ-8 revealed that γ-8 TDAAs binds to γ-8 alone without AMPA receptors. Homology modeling of γ-8, based on the crystal structures of a distant TARP homologue, murine claudin 19, in conjunction with knowledge of two γ-8 residues previously identified as critical for the LY3130481 TARP-dependent selectivity provided the basis for a binding mode prediction. This allowed further rational mutational studies for characterization of the structural determinants in TARP γ-8 for LY3130481 activities, both thermodynamically as well as kinetically.
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Affiliation(s)
- Matthew R. Lee
- Lilly
Biotechnology Center, Eli Lilly and Company, 10300 Campus Point Dr. #200, San Diego, California 92121, United States
| | - Kevin M. Gardinier
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - Douglas L. Gernert
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - Douglas A. Schober
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - Rebecca A. Wright
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - He Wang
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - Yuewei Qian
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - Jeffrey M. Witkin
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - Eric S. Nisenbaum
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
| | - Akihiko S. Kato
- Neuroscience
Discovery, Lilly Research Laboratory, 355 E Merril St., Indianapolis, Indiana 46285, United States
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10
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Park J, Chávez AE, Mineur YS, Morimoto-Tomita M, Lutzu S, Kim KS, Picciotto MR, Castillo PE, Tomita S. CaMKII Phosphorylation of TARPγ-8 Is a Mediator of LTP and Learning and Memory. Neuron 2016; 92:75-83. [PMID: 27667007 DOI: 10.1016/j.neuron.2016.09.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Revised: 06/25/2016] [Accepted: 08/29/2016] [Indexed: 11/28/2022]
Abstract
Protein phosphorylation is an essential step for the expression of long-term potentiation (LTP), a long-lasting, activity-dependent strengthening of synaptic transmission widely regarded as a cellular mechanism underlying learning and memory. At the core of LTP is the synaptic insertion of AMPA receptors (AMPARs) triggered by the NMDA receptor-dependent activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). However, the CaMKII substrate that increases AMPAR-mediated transmission during LTP remains elusive. Here, we identify the hippocampus-enriched TARPγ-8, but not TARPγ-2/3/4, as a critical CaMKII substrate for LTP. We found that LTP induction increases TARPγ-8 phosphorylation, and that CaMKII-dependent enhancement of AMPAR-mediated transmission requires CaMKII phosphorylation sites of TARPγ-8. Moreover, LTP and memory formation, but not basal transmission, are significantly impaired in mice lacking CaMKII phosphorylation sites of TARPγ-8. Together, these findings demonstrate that TARPγ-8 is a crucial mediator of CaMKII-dependent LTP and therefore a molecular target that controls synaptic plasticity and associated cognitive functions.
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Affiliation(s)
- Joongkyu Park
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Andrés E Chávez
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2340000, Chile
| | - Yann S Mineur
- Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Megumi Morimoto-Tomita
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Stefano Lutzu
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Kwang S Kim
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Marina R Picciotto
- Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Program in Cellular Neuroscience, Neurodegeneration, and Repair, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA; Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA.
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11
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Wang JG, Wang YL, Xu F, Zhao JX, Zhou SY, Yu Y, Chazot PL, Wang XF, Lu CB. Activity- and development-dependent down-regulation of TARPγ8 and GluA1 in cultured rat hippocampal neurons. Acta Pharmacol Sin 2016; 37:303-11. [PMID: 26725511 DOI: 10.1038/aps.2015.112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 10/26/2015] [Indexed: 01/16/2023] Open
Abstract
AIM Transmembrane AMPA receptor regulatory proteins (TARPs) regulate the trafficking and expression of AMPA receptors that are essential for the fast excitatory synaptic transmission and plasticity in the brain. This study aimed to investigate the activity-dependent regulation of TARPγ8 in cultured rat hippocampal neurons. METHODS Rat hippocampal neurons cultured for 7-8 DIV or 17-18 DIV were exposed to the AMPA receptor agonist AMPA at a non-toxic concentration (100 μmol/L) for 4 h. The protein levels of TARPγ8 and AMPA receptor subunits (GluA1 and GluA2) were measured using Western blotting analysis. AMPA-induced currents were recorded in the neurons using a whole-cell recording method. RESULTS Four-hour exposure to AMPA significantly decreased the protein levels of TARPγ8 and GluA1 in the neurons at 17-18 DIV, but did not change the protein level of TARPγ8 in the neurons cultured at 7-8 DIV. AMPA-induced down-regulation of TARPγ8 and GluA1 was largely blocked by the calpain inhibitor calpeptin (50 μmol/L), but not affected by the caspase inhibitor zVAD (50 μmol/L). Four-hour exposure to AMPA significantly decreased AMPA-induced currents in the neurons at 17-18 DIV, which was blocked by co-exposure to calpeptin (50 μmol/L). CONCLUSION The down-regulation of TARPγ8 and GluA1 protein levels and AMPA-induced currents in cultured rat hippocampal neurons is activity- and development-dependent, and mediated by endogenous calpain.
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12
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MacLean DM, Ramaswamy SS, Du M, Howe JR, Jayaraman V. Stargazin promotes closure of the AMPA receptor ligand-binding domain. ACTA ACUST UNITED AC 2015; 144:503-12. [PMID: 25422502 PMCID: PMC4242809 DOI: 10.1085/jgp.201411287] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Stargazin enhances closure of the AMPA receptor ligand-binding domain, thereby facilitating channel activation. Transmembrane AMPA receptor (AMPAR) regulatory proteins (TARPs) markedly enhance AMPAR function, altering ligand efficacy and receptor gating kinetics and thereby shaping the postsynaptic response. The structural mechanism underlying TARP effects on gating, however, is unknown. Here we find that the prototypical member of the TARP family, stargazin or γ-2, rescues gating deficits in AMPARs carrying mutations that destabilize the closed-cleft states of the ligand-binding domain (LBD), suggesting that stargazin reverses the effects of these mutations and likely stabilizes closed LBD states. Furthermore, stargazin promotes a more closed conformation of the LBD, as indicated by reduced accessibility to the large antagonist NBQX. Consistent with the functional studies, luminescence resonance energy transfer experiments directly demonstrate that the AMPAR LBD is on average more closed in the presence of stargazin, in both the apo and agonist-bound states. The additional cleft closure and/or stabilization of the more closed-cleft states of the LBD is expected to translate to higher agonist efficacy and could contribute to the structural mechanism for stargazin modulation of AMPAR function.
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Affiliation(s)
- David M MacLean
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - Swarna S Ramaswamy
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - Mei Du
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
| | - James R Howe
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06530
| | - Vasanthi Jayaraman
- Department of Biochemistry and Molecular Biology, Center for Membrane Biology, University of Texas Health Science Center, Houston, TX 77030
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13
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14
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Haering SC, Tapken D, Pahl S, Hollmann M. Auxiliary subunits: shepherding AMPA receptors to the plasma membrane. MEMBRANES 2014; 4:469-90. [PMID: 25110960 PMCID: PMC4194045 DOI: 10.3390/membranes4030469] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 07/17/2014] [Accepted: 07/25/2014] [Indexed: 11/24/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric ligand-gated cation channels that mediate excitatory signal transmission in the central nervous system (CNS) of vertebrates. The members of the iGluR subfamily of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPARs) mediate most of the fast excitatory signal transmission, and their abundance in the postsynaptic membrane is a major determinant of the strength of excitatory synapses. Therefore, regulation of AMPAR trafficking to the postsynaptic membrane is an important constituent of mechanisms involved in learning and memory formation, such as long-term potentiation (LTP) and long-term depression (LTD). Auxiliary subunits play a critical role in the facilitation and regulation of AMPAR trafficking and function. The currently identified auxiliary subunits of AMPARs are transmembrane AMPA receptor regulatory proteins (TARPs), suppressor of lurcher (SOL), cornichon homologues (CNIHs), synapse differentiation-induced gene I (SynDIG I), cysteine-knot AMPAR modulating proteins 44 (CKAMP44), and germ cell-specific gene 1-like (GSG1L) protein. In this review we summarize our current knowledge of the modulatory influence exerted by these important but still underappreciated proteins.
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Affiliation(s)
- Simon C Haering
- Department of Biochemistry I-Receptor Biochemistry, Ruhr University Bochum, Universitätsstraße 150, 44780 Bochum, Germany.
| | - Daniel Tapken
- Department of Biochemistry I-Receptor Biochemistry, Ruhr University Bochum, Universitätsstraße 150, 44780 Bochum, Germany.
| | - Steffen Pahl
- Department of Biochemistry I-Receptor Biochemistry, Ruhr University Bochum, Universitätsstraße 150, 44780 Bochum, Germany.
| | - Michael Hollmann
- Department of Biochemistry I-Receptor Biochemistry, Ruhr University Bochum, Universitätsstraße 150, 44780 Bochum, Germany.
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Hamad MIK, Jack A, Klatt O, Lorkowski M, Strasdeit T, Kott S, Sager C, Hollmann M, Wahle P. Type I TARPs promote dendritic growth of early postnatal neocortical pyramidal cells in organotypic cultures. Development 2014; 141:1737-48. [PMID: 24667327 DOI: 10.1242/dev.099697] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazole propionate glutamate receptors (AMPARs) have been implicated in the establishment of dendritic architecture. The transmembrane AMPA receptor regulatory proteins (TARPs) regulate AMPAR function and trafficking into synaptic membranes. In the current study, we employ type I and type II TARPs to modulate expression levels and function of endogenous AMPARs and investigate in organotypic cultures (OTCs) of rat occipital cortex whether this influences neuronal differentiation. Our results show that in early development [5-10 days in vitro (DIV)] only the type I TARP γ-8 promotes pyramidal cell dendritic growth by increasing spontaneous calcium amplitude and GluA2/3 expression in soma and dendrites. Later in development (10-15 DIV), the type I TARPs γ-2, γ-3 and γ-8 promote dendritic growth, whereas γ-4 reduced dendritic growth. The type II TARPs failed to alter dendritic morphology. The TARP-induced dendritic growth was restricted to the apical dendrites of pyramidal cells and it did not affect interneurons. Moreover, we studied the effects of short hairpin RNA-induced knockdown of endogenous γ-8 and showed a reduction of dendritic complexity and amplitudes of spontaneous calcium transients. In addition, the cytoplasmic tail (CT) of γ-8 was required for dendritic growth. Single-cell calcium imaging showed that the γ-8 CT domain increases amplitude but not frequency of calcium transients, suggesting a regulatory mechanism involving the γ-8 CT domain in the postsynaptic compartment. Indeed, the effect of γ-8 overexpression was reversed by APV, indicating a contribution of NMDA receptors. Our results suggest that selected type I TARPs influence activity-dependent dendritogenesis of immature pyramidal neurons.
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Affiliation(s)
- Mohammad I K Hamad
- Developmental Neurobiology Group, Faculty for Biology and Biotechnology, Ruhr University Bochum, Bochum 44780, Germany
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16
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Drummond JB, Tucholski J, Haroutunian V, Meador-Woodruff JH. Transmembrane AMPA receptor regulatory protein (TARP) dysregulation in anterior cingulate cortex in schizophrenia. Schizophr Res 2013; 147:32-38. [PMID: 23566497 PMCID: PMC3650109 DOI: 10.1016/j.schres.2013.03.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 03/07/2013] [Accepted: 03/11/2013] [Indexed: 02/09/2023]
Abstract
The glutamate hypothesis of schizophrenia proposes that abnormal glutamatergic neurotransmission occurs in this illness, and a major contribution may involve dysregulation of the AMPA subtype of ionotropic glutamate receptor (AMPAR). Transmembrane AMPAR regulatory proteins (TARPs) form direct associations with AMPARs to modulate the trafficking and biophysical functions of these receptors, and their dysregulation may alter the localization and activity of AMPARs, thus having a potential role in the pathophysiology of schizophrenia. We performed comparative quantitative real-time PCR and Western blot analysis to measure transcript (schizophrenia, N=25; comparison subjects, N=25) and protein (schizophrenia, N=36; comparison subjects, N=33) expression of TARPs (γ subunits 1-8) in the anterior cingulate cortex (ACC) in schizophrenia and a comparison group. TARP expression was also measured in frontal cortex of rats chronically treated with haloperidol decanoate (28.5mg/kg every three weeks for nine months) to determine the effect of antipsychotic treatment on the expression of these molecules. We found decreased transcript expression of TARP γ-8 in schizophrenia. At the protein level, γ-3 and γ-5 were increased, while γ-4, γ-7 and γ-8 were decreased in schizophrenia. No changes in any of the molecules were noted in the frontal cortex of haloperidol-treated rats. TARPs are abnormally expressed at transcript and protein levels in ACC in schizophrenia, and these changes are likely due to the illness and not to the antipsychotic treatment. Alterations in the expression of TARPs may contribute to the pathophysiology of schizophrenia, and represent a potential mechanism of glutamatergic dysregulation in this illness.
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Affiliation(s)
- Jana B. Drummond
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, CIRC 589A, 1719 6th Ave South, Birmingham, AI 25294 USA
,Corresponding author. . Tel.: 205.996.6164; fax: 205.975.4879
| | - Janusz Tucholski
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, CIRC 589A, 1719 6th Ave South, Birmingham, AI 25294 USA
| | - Vahram Haroutunian
- Department of Psychiatry, Mount Sinai School of Medicine, James J Peters Veteran Adminis Room 4F-20 130 West Kingsbridge Road Bronx, NY 10468 USA
| | - James H. Meador-Woodruff
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, CIRC 589A, 1719 6th Ave South, Birmingham, AI 25294 USA
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17
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Erbin interacts with TARP γ-2 for surface expression of AMPA receptors in cortical interneurons. Nat Neurosci 2013; 16:290-9. [DOI: 10.1038/nn.3320] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 12/24/2012] [Indexed: 12/15/2022]
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18
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Chang PKY, Verbich D, McKinney RA. AMPA receptors as drug targets in neurological disease - advantages, caveats, and future outlook. Eur J Neurosci 2012; 35:1908-16. [DOI: 10.1111/j.1460-9568.2012.08165.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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19
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Cheng J, Dong J, Cui Y, Wang L, Wu B, Zhang C. Interacting partners of AMPA-type glutamate receptors. J Mol Neurosci 2012; 48:441-7. [PMID: 22361832 DOI: 10.1007/s12031-012-9724-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/10/2012] [Indexed: 01/28/2023]
Abstract
Glutamate is the principal excitatory neurotransmitter in the brain. The alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropionic (AMPA) receptors, as one of several types of endogenous ionotropic glutamate receptors, mediate the fast excitatory synaptic transmission that is essential for information processing and integration in the mammalian brain. Modifications of AMPA receptors are assumed to be the molecular basis underlying learning and memory, and impairments of AMPA receptors cause certain neurological diseases, including epilepsy, autism spectrum disorders, and Alzheimer's disease. Thus, extensive studies have been conducted, and these have revealed a complex protein-protein network controlling the expression, trafficking, and function of AMPA receptors in neurons. Here, we summarize the interacting partners of AMPA-type glutamate receptors and the functional implications of these interactions.
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Affiliation(s)
- Juan Cheng
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Peking University, Beijing 100871, China
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20
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Shevtsova O, Leitch B. Selective loss of AMPA receptor subunits at inhibitory neuron synapses in the cerebellum of the ataxic stargazer mouse. Brain Res 2012; 1427:54-64. [DOI: 10.1016/j.brainres.2011.10.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 10/07/2011] [Accepted: 10/12/2011] [Indexed: 10/16/2022]
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21
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Straub C, Tomita S. The regulation of glutamate receptor trafficking and function by TARPs and other transmembrane auxiliary subunits. Curr Opin Neurobiol 2011; 22:488-95. [PMID: 21993243 DOI: 10.1016/j.conb.2011.09.005] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 09/16/2011] [Accepted: 09/17/2011] [Indexed: 02/06/2023]
Abstract
At excitatory synapses in the brain, glutamate released from nerve terminals binds to glutamate receptors to mediate signaling between neurons. Glutamate receptors expressed in heterologous cells show ion channel activity. Recently, native glutamate receptors were shown to contain auxiliary subunits that modulate the trafficking and/or channel properties. The AMPA receptor (AMPAR) can contain TARP and CNIHs as the auxiliary subunits, whereas kainate receptor (KAR) can contain the Neto auxiliary subunit. Each of these auxiliary subunits uniquely modulates the glutamate receptors, and determines properties of native glutamate receptors. A thorough elucidation of the properties of native glutamate receptor complexes is indispensable for the understanding of the molecular machinery that regulates glutamate receptors and excitatory synaptic transmission in the brain.
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Affiliation(s)
- Christoph Straub
- Program in Cellular Neuroscience, Neurodegeneration and Repair (CNNR), Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, United States
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22
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Abstract
Pore-forming subunits of ion channels show channel activity in heterologous cells. However, recombinant and native channels often differ in their channel properties. These discrepancies are resolved by the identification of channel auxiliary subunits. In this review article, an auxiliary subunit of ligand-gated ion channels is defined using four criteria: (1) as a Non-pore-forming subunit, (2) direct and stable interaction with a pore-forming subunit, (3) modulation of channel properties and/or trafficking in heterologous cells, (4) necessity in vivo. We focus particularly on three classes of ionotropic glutamate receptors and their transmembrane interactors. Precise identification of auxiliary subunits and reconstruction of native glutamate receptors will open new directions to understanding the brain and its functions.
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Affiliation(s)
- Dan Yan
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
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23
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Jackson AC, Nicoll RA. The expanding social network of ionotropic glutamate receptors: TARPs and other transmembrane auxiliary subunits. Neuron 2011; 70:178-99. [PMID: 21521608 DOI: 10.1016/j.neuron.2011.04.007] [Citation(s) in RCA: 288] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2011] [Indexed: 12/25/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) underlie rapid, excitatory synaptic signaling throughout the CNS. After years of intense research, our picture of iGluRs has evolved from them being companionless in the postsynaptic membrane to them being the hub of dynamic supramolecular signaling complexes, interacting with an ever-expanding litany of other proteins that regulate their trafficking, scaffolding, stability, signaling, and turnover. In particular, the discovery that transmembrane AMPA receptor regulatory proteins (TARPs) are AMPA receptor auxiliary subunits that are critical determinants of their trafficking, gating, and pharmacology has changed the way we think about iGluR function. Recently, a number of novel transmembrane proteins have been uncovered that may also serve as iGluR auxiliary proteins. Here we review pivotal developments in our understanding of the role of TARPs in AMPA receptor trafficking and gating, and provide an overview of how newly discovered transmembrane proteins expand our view of iGluR function in the CNS.
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Affiliation(s)
- Alexander C Jackson
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.
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24
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Stargazin (TARP gamma-2) is required for compartment-specific AMPA receptor trafficking and synaptic plasticity in cerebellar stellate cells. J Neurosci 2011; 31:3939-52. [PMID: 21411637 DOI: 10.1523/jneurosci.5134-10.2011] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In the cerebellar cortex, parallel fiber-to-stellate cell (PF-SC) synapses exhibit a form of synaptic plasticity manifested as a switch in the subunit composition of synaptic AMPA receptors (AMPARs) from calcium-permeable, GluA2-lacking to calcium-impermeable, GluA2-containing receptors. Here, we examine the role of stargazin (γ-2), canonical member of the transmembrane AMPAR regulatory protein (TARP) family, in the regulation of GluA2-lacking AMPARs and synaptic plasticity in SCs from epileptic and ataxic stargazer mutant mice. We found that AMPAR-mediated synaptic transmission is severely diminished in stargazer SCs, and that the rectification index (RI) of AMPAR current is reduced. Activity-dependent plasticity in the rectification of synaptic AMPARs is also impaired in stargazer SCs. Despite the dramatic loss in synaptic AMPARs, extrasynaptic AMPARs are preserved. We then examined the role of stargazin in regulating the rectification of extrasynaptic AMPARs in nucleated patches and found, in contrast to previous reports, that wild-type extrasynaptic AMPARs have moderate RI values (average RI = 0.38), while those in stargazer SCs are low (average RI = 0.24). The GluA2-lacking AMPAR blocker, philanthotoxin-433 (PhTx-433), was used as an alternative measure of GluA2 content in wild-type and stargazer SCs. Despite the difference in RI, PhTx-433 sensitivity of both synaptic and extrasynaptic AMPARs remains unchanged, suggesting that the dramatic changes in RI and the impairment in synaptic plasticity observed in the stargazer mouse are not the result of a specific impairment in GluA2 trafficking. Together, these data suggest that stargazin regulates compartment-specific AMPAR trafficking, as well as activity-dependent plasticity in synaptic AMPAR rectification at cerebellar PF-SC synapses.
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Kato AS, Gill MB, Ho MT, Yu H, Tu Y, Siuda ER, Wang H, Qian YW, Nisenbaum ES, Tomita S, Bredt DS. Hippocampal AMPA receptor gating controlled by both TARP and cornichon proteins. Neuron 2011; 68:1082-96. [PMID: 21172611 DOI: 10.1016/j.neuron.2010.11.026] [Citation(s) in RCA: 138] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2010] [Indexed: 11/17/2022]
Abstract
Transmembrane AMPA receptor regulatory proteins (TARPs) and cornichon proteins (CNIH-2/3) independently modulate AMPA receptor trafficking and gating. However, the potential for interactions of these subunits within an AMPA receptor complex is unknown. Here, we find that TARPs γ-4, γ-7, and γ-8, but not γ-2, γ-3, or γ-5, cause AMPA receptors to "resensitize" upon continued glutamate application. With γ-8, resensitization occurs with all GluA subunit combinations; however, γ-8-containing hippocampal neurons do not display resensitization. In recombinant systems, CNIH-2 abrogates γ-8-mediated resensitization and modifies AMPA receptor pharmacology and gating to match that of hippocampal neurons. In hippocampus, γ-8 and CNIH-2 associate in postsynaptic densities and CNIH-2 protein levels are markedly diminished in γ-8 knockout mice. Manipulating neuronal CNIH-2 levels modulates the electrophysiological properties of extrasynaptic and synaptic γ-8-containing AMPA receptors. Thus, γ-8 and CNIH-2 functionally interact with common hippocampal AMPA receptor complexes to modulate synergistically kinetics and pharmacology.
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Affiliation(s)
- Akihiko S Kato
- Department of Neuroscience, Eli Lilly and Company, Indianapolis, IN 46285, USA.
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26
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Sumioka A, Yan D, Tomita S. TARP phosphorylation regulates synaptic AMPA receptors through lipid bilayers. Neuron 2010; 66:755-67. [PMID: 20547132 DOI: 10.1016/j.neuron.2010.04.035] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2010] [Indexed: 01/25/2023]
Abstract
Neurons use neurotransmitters to communicate across synapses, constructing neural circuits in the brain. AMPA-type glutamate receptors are the predominant excitatory neurotransmitter receptors mediating fast synaptic transmission. AMPA receptors localize at synapses by forming protein complexes with transmembrane AMPA receptor regulatory proteins (TARPs) and PSD-95-like membrane-associated guanylate kinases. Among the three classes of ionotropic glutamate receptors (AMPA, NMDA, and kainate type), AMPA receptor activity is most regulatable by neuronal activity to adjust synaptic strength. Here, we mutated the prototypical TARP, stargazin, and found that TARP phosphorylation regulates synaptic AMPA receptor activity in vivo. We also found that stargazin interacts with negatively charged lipid bilayers in a phosphorylation-dependent manner and that the lipid interaction inhibited stargazin binding to PSD-95. Cationic lipids dissociated stargazin from lipid bilayers and enhanced synaptic AMPA receptor activity in a stargazin phosphorylation-dependent manner. Thus, TARP phosphorylation plays a critical role in regulating AMPA receptor-mediated synaptic transmission via a lipid bilayer interaction.
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Affiliation(s)
- Akio Sumioka
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
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Tomita S. Regulation of ionotropic glutamate receptors by their auxiliary subunits. Physiology (Bethesda) 2010; 25:41-9. [PMID: 20134027 DOI: 10.1152/physiol.00033.2009] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Glutamate receptors are major excitatory receptors in the brain. Recent findings have established auxiliary subunits of glutamate receptors as critical modulators of synaptic transmission, synaptic plasticity, and neurological disorder. The elucidation of the molecular rules governing glutamate receptors and subunits will improve our understanding of synapses and of neural-circuit regulation in the brain.
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Affiliation(s)
- Susumu Tomita
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, USA.
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28
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Roles of stargazin and phosphorylation in the control of AMPA receptor subcellular distribution. Nat Neurosci 2009; 12:888-96. [PMID: 19543281 DOI: 10.1038/nn.2340] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Accepted: 04/10/2009] [Indexed: 11/08/2022]
Abstract
Understanding how the subcellular fate of newly synthesized AMPA receptors (AMPARs) is controlled is important for elucidating the mechanisms of neuronal function. We examined the effect of increased synthesis of AMPAR subunits on their subcellular distribution in rat hippocampal neurons. Virally expressed AMPAR subunits (GluR1 or GluR2) accumulated in cell bodies and replaced endogenous dendritic AMPAR with little effect on total dendritic amounts and caused no change in synaptic transmission. Coexpressing stargazin (STG) or mimicking GluR1 phosphorylation enhanced dendritic GluR1 levels by protecting GluR1 from lysosomal degradation. However, STG interaction or GluR1 phosphorylation did not increase surface or synaptic GluR1 levels. Unlike GluR1, STG did not protect GluR2 from lysosomal degradation or increase dendritic GluR2 levels. In general, AMPAR surface levels, and not intracellular amounts, correlated strongly with synaptic levels. Our results suggest that AMPAR surface expression, but not its intracellular production or accumulation, is critical for regulating synaptic transmission.
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Schwenk J, Harmel N, Zolles G, Bildl W, Kulik A, Heimrich B, Chisaka O, Jonas P, Schulte U, Fakler B, Klocker N. Functional Proteomics Identify Cornichon Proteins as Auxiliary Subunits of AMPA Receptors. Science 2009; 323:1313-9. [DOI: 10.1126/science.1167852] [Citation(s) in RCA: 304] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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