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Qneibi M, Bdir S, Bdair M, Aldwaik SA, Heeh M, Sandouka D, Idais T. Exploring the role of AMPA receptor auxiliary proteins in synaptic functions and diseases. FEBS J 2024. [PMID: 39394632 DOI: 10.1111/febs.17287] [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: 05/18/2024] [Revised: 08/21/2024] [Accepted: 09/20/2024] [Indexed: 10/13/2024]
Abstract
α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) ionotropic glutamate receptors (AMPARs) mediate rapid excitatory synaptic transmission in the mammalian brain, primarily driven by the neurotransmitter glutamate. The modulation of AMPAR activity, particularly calcium-permeable AMPARs (CP-AMPARs), is crucially influenced by various auxiliary subunits. These subunits are integral membrane proteins that bind to the receptor's core and modify its functional properties, including ion channel kinetics and receptor trafficking. This review comprehensively catalogs all known AMPAR auxiliary proteins, providing vital insights into the biochemical mechanisms governing synaptic modulation and the specific impact of CP-AMPARs compared to their calcium-impermeable AMPA receptor (CI-AMPARs). Understanding the complex interplay between AMPARs and their auxiliary subunits in different brain regions is essential for elucidating their roles in cognitive functions such as learning and memory. Importantly, alterations in these auxiliary proteins' expression, function or interactions have been implicated in various neurological disorders. Aberrant signaling through CP-AMPARs, in particular, is associated with severe synaptic dysfunctions across neurodevelopmental, neurodegenerative and psychiatric conditions. Targeting the distinct properties of AMPAR-auxiliary subunit complexes, especially those involving CP-AMPARs, could disclose new therapeutic strategies, potentially allowing for more precise interventions in treating complex neuronal disorders.
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Affiliation(s)
- Mohammad Qneibi
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
| | - Sosana Bdir
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
| | - Mohammad Bdair
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
| | - Samia Ammar Aldwaik
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
| | | | - Dana Sandouka
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
| | - Tala Idais
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine
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2
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Ivica J, Kejzar N, Ho H, Stockwell I, Kuchtiak V, Scrutton AM, Nakagawa T, Greger IH. Proton-triggered rearrangement of the AMPA receptor N-terminal domains impacts receptor kinetics and synaptic localization. Nat Struct Mol Biol 2024:10.1038/s41594-024-01369-5. [PMID: 39138332 DOI: 10.1038/s41594-024-01369-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 07/08/2024] [Indexed: 08/15/2024]
Abstract
AMPA glutamate receptors (AMPARs) are ion channel tetramers that mediate the majority of fast excitatory synaptic transmission. They are composed of four subunits (GluA1-GluA4); the GluA2 subunit dominates AMPAR function throughout the forebrain. Its extracellular N-terminal domain (NTD) determines receptor localization at the synapse, ensuring reliable synaptic transmission and plasticity. This synaptic anchoring function requires a compact NTD tier, stabilized by a GluA2-specific NTD interface. Here we show that low pH conditions, which accompany synaptic activity, rupture this interface. All-atom molecular dynamics simulations reveal that protonation of an interfacial histidine residue (H208) centrally contributes to NTD rearrangement. Moreover, in stark contrast to their canonical compact arrangement at neutral pH, GluA2 cryo-electron microscopy structures exhibit a wide spectrum of NTD conformations under acidic conditions. We show that the consequences of this pH-dependent conformational control are twofold: rupture of the NTD tier slows recovery from desensitized states and increases receptor mobility at mouse hippocampal synapses. Therefore, a proton-triggered NTD switch will shape both AMPAR location and kinetics, thereby impacting synaptic signal transmission.
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Affiliation(s)
- Josip Ivica
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
| | - Nejc Kejzar
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Hinze Ho
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Imogen Stockwell
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
| | - Viktor Kuchtiak
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Alexander M Scrutton
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - Ingo H Greger
- Neurobiology Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge, UK.
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León-García F, García-Laynes F, Estrada-Tapia G, Monforte-González M, Martínez-Estevez M, Echevarría-Machado I. In Silico Analysis of Glutamate Receptors in Capsicum chinense: Structure, Evolution, and Molecular Interactions. PLANTS (BASEL, SWITZERLAND) 2024; 13:812. [PMID: 38592787 PMCID: PMC10975470 DOI: 10.3390/plants13060812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Revised: 02/27/2024] [Accepted: 03/06/2024] [Indexed: 04/11/2024]
Abstract
Plant glutamate receptors (GLRs) are integral membrane proteins that function as non-selective cation channels, involved in the regulation of developmental events crucial in plants. Knowledge of these proteins is restricted to a few species and their true agonists are still unknown in plants. Using tomato SlGLRs, a search was performed in the pepper database to identify GLR sequences in habanero pepper (Capsicum chinense Jacq.). Structural, phylogenetic, and orthology analysis of the CcGLRs, as well as molecular docking and protein interaction networks, were conducted. Seventeen CcGLRs were identified, which contained the characteristic domains of GLR. The variation of conserved residues in the M2 transmembrane domain between members suggests a difference in ion selectivity and/or conduction. Also, new conserved motifs in the ligand-binding regions are reported. Duplication events seem to drive the expansion of the species, and these were located in the evolution by using orthologs. Molecular docking analysis allowed us to identify differences in the agonist binding pocket between CcGLRs, which suggest the existence of different affinities for amino acids. The possible interaction of some CcGLRs with proteins leads to suggesting specific functions for them within the plant. These results offer important functional clues for CcGLR, probably extrapolated to other Solanaceae.
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Affiliation(s)
| | | | | | | | | | - Ileana Echevarría-Machado
- Unidad de Biología Integrativa, Centro de Investigación Científica de Yucatán, Calle 43, #130, x 32 and 34, Mérida 97205, Yucatán, Mexico; (F.L.-G.); (M.M.-G.); (M.M.-E.)
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Cao YY, Wu LL, Li XN, Yuan YL, Zhao WW, Qi JX, Zhao XY, Ward N, Wang J. Molecular Mechanisms of AMPA Receptor Trafficking in the Nervous System. Int J Mol Sci 2023; 25:111. [PMID: 38203282 PMCID: PMC10779435 DOI: 10.3390/ijms25010111] [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: 11/24/2023] [Revised: 12/15/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024] Open
Abstract
Synaptic plasticity enhances or reduces connections between neurons, affecting learning and memory. Postsynaptic AMPARs mediate greater than 90% of the rapid excitatory synaptic transmission in glutamatergic neurons. The number and subunit composition of AMPARs are fundamental to synaptic plasticity and the formation of entire neural networks. Accordingly, the insertion and functionalization of AMPARs at the postsynaptic membrane have become a core issue related to neural circuit formation and information processing in the central nervous system. In this review, we summarize current knowledge regarding the related mechanisms of AMPAR expression and trafficking. The proteins related to AMPAR trafficking are discussed in detail, including vesicle-related proteins, cytoskeletal proteins, synaptic proteins, and protein kinases. Furthermore, significant emphasis was placed on the pivotal role of the actin cytoskeleton, which spans throughout the entire transport process in AMPAR transport, indicating that the actin cytoskeleton may serve as a fundamental basis for AMPAR trafficking. Additionally, we summarize the proteases involved in AMPAR post-translational modifications. Moreover, we provide an overview of AMPAR transport and localization to the postsynaptic membrane. Understanding the assembly, trafficking, and dynamic synaptic expression mechanisms of AMPAR may provide valuable insights into the cognitive decline associated with neurodegenerative diseases.
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Affiliation(s)
- Yi-Yang Cao
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Ling-Ling Wu
- School of Medicine, Shanghai University, Shanghai 200444, China;
| | - Xiao-Nan Li
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Yu-Lian Yuan
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Wan-Wei Zhao
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Jing-Xuan Qi
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Xu-Yu Zhao
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
| | - Natalie Ward
- Medical Laboratory, Exceptional Community Hospital, 19060 N John Wayne Pkwy, Maricopa, AZ 85139, USA;
| | - Jiao Wang
- Laboratory of Molecular Neural Biology, School of Life Sciences, Shanghai University, Shanghai 200444, China; (Y.-Y.C.); (X.-N.L.); (Y.-L.Y.); (W.-W.Z.); (J.-X.Q.); (X.-Y.Z.)
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5
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Reusswig F, Yilmaz M, Brechtenkamp M, Krueger I, Metz LM, Klöcker N, Lammert E, Elvers M. The NMDA receptor regulates integrin activation, ATP release and arterial thrombosis through store-operated Ca 2+ entry in platelets. Front Cardiovasc Med 2023; 10:1171831. [PMID: 37252113 PMCID: PMC10217778 DOI: 10.3389/fcvm.2023.1171831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/27/2023] [Indexed: 05/31/2023] Open
Abstract
Introduction Platelet activation and thrombus formation is crucial for hemostasis, but also trigger arterial thrombosis. Calcium mobilization plays an important role in platelet activation, because many cellular processes depend on the level of intracellular Ca2+ ([Ca2+](i)), such as integrin activation, degranulation, cytoskeletal reorganization. Different modulators of Ca2+ signaling have been implied, such as STIM1, Orai1, CyPA, SGK1, etc. Also, the N-methyl-D-aspartate receptor (NMDAR) was identified to contribute to Ca2+ signaling in platelets. However, the role of the NMDAR in thrombus formation is not well defined. Methods In vitro and in vivo analysis of platelet-specific NMDAR knock-out mice. Results In this study, we analyzed Grin1fl/fl-Pf4-Cre+ mice with a platelet-specific knock-out of the essential GluN1 subunit of the NMDAR. We found reduced store-operated Ca2+ entry (SOCE), but unaltered store release in GluN1-deficient platelets. Defective SOCE resulted in reduced Src and PKC substrate phosphorylation following stimulation of glycoprotein (GP)VI or the thrombin receptor PAR4 followed by decreased integrin activation but unaltered degranulation. Consequently, thrombus formation on collagen under flow conditions was reduced ex vivo, and Grin1fl/fl-Pf4-Cre+ mice were protected against arterial thrombosis. Results from human platelets treated with the NMDAR antagonist MK-801 revealed a crucial role of the NMDAR in integrin activation and Ca2+ homeostasis in human platelets as well. Conclusion NMDAR signaling is important for SOCE in platelets and contributes to platelet activation and arterial thrombosis. Thus, the NMDAR represents a novel target for anti-platelet therapy in cardiovascular disease (CVD).
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Affiliation(s)
- Friedrich Reusswig
- Department of Vascular- and Endovascular Surgery, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
| | - Münteha Yilmaz
- Department of Vascular- and Endovascular Surgery, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
| | - Marius Brechtenkamp
- Department of Vascular- and Endovascular Surgery, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
| | - Irena Krueger
- Department of Vascular- and Endovascular Surgery, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
| | - Lisa Maria Metz
- Department of Vascular- and Endovascular Surgery, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Medical Faculty and University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
| | - Eckhard Lammert
- Institute for Vascular and Islet Cell Biology, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich-Heine University, Düsseldorf, Germany
- German Center for Diabetes Research (DZD e.V.), Helmholtz Zentrum München, Neuherberg, Germany
- Institute of Metabolic Physiology, Heinrich Heine University, Düsseldorf, Germany
| | - Margitta Elvers
- Department of Vascular- and Endovascular Surgery, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
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Chen HS, Wang J, Li HH, Wang X, Zhang SQ, Deng T, Li YK, Zou RS, Wang HJ, Zhu R, Xie WL, Zhao G, Wang F, Chen JG. Long noncoding RNA Gm2694 drives depressive-like behaviors in male mice by interacting with GRP78 to disrupt endoplasmic reticulum homeostasis. SCIENCE ADVANCES 2022; 8:eabn2496. [PMID: 36459549 PMCID: PMC10936050 DOI: 10.1126/sciadv.abn2496] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 10/18/2022] [Indexed: 06/17/2023]
Abstract
Long noncoding RNAs (lncRNAs) are involved in various biological processes and implicated in the regulation of neuronal activity, but the potential role of lncRNAs in depression remains largely unknown. Here, we identified that lncRNA Gm2694 was increased in the medial prefrontal cortex (mPFC) of male mice subjected to chronic social defeat stress (CSDS). The down-regulation of Gm2694 in the mPFC alleviated CSDS-induced depressive-like behaviors through enhanced excitatory synaptic transmission. Furthermore, we found that Gm2694 preferentially interacted with the carboxyl-terminal domain of 78-kilodalton glucose-regulated protein (GRP78), which abrogated GRP78 function and disrupted endoplasmic reticulum homeostasis, resulting in a reduction of the surface expression of AMPA receptors (AMPARs). Overexpression of GRP78 in the mPFC promoted the surface expression of AMPARs and attenuated the CSDS-induced depressive-like behaviors of mice. Together, our results unraveled a previously unknown role of Gm2694 in regulating endoplasmic reticulum homeostasis and excitatory synaptic transmission in depression.
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Affiliation(s)
- Hong-Sheng Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
- The Research Center for Depression, Tongji Medical College, Huazhong University of Science, 430030 Wuhan, China
- The Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, 430030 Wuhan, China
| | - Ji Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Hou-Hong Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Xiao Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Shao-Qi Zhang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Tan Deng
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Yu-Ke Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Ruo-Si Zou
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Hua-Jie Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Rui Zhu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Wen-Long Xie
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Gang Zhao
- Department of Emergency Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430022 Wuhan, China
| | - Fang Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
- The Research Center for Depression, Tongji Medical College, Huazhong University of Science, 430030 Wuhan, China
- The Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, 430030 Wuhan, China
- The Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, 430030 Wuhan, China
- Laboratory of Neuropsychiatric Diseases, The Institute of Brain Research, Huazhong University of Science and Technology, 430030 Wuhan, China
| | - Jian-Guo Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, China
- The Research Center for Depression, Tongji Medical College, Huazhong University of Science, 430030 Wuhan, China
- The Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, 430030 Wuhan, China
- The Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, 430030 Wuhan, China
- Laboratory of Neuropsychiatric Diseases, The Institute of Brain Research, Huazhong University of Science and Technology, 430030 Wuhan, China
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Matthews PM, Pinggera A, Kampjut D, Greger IH. Biology of AMPA receptor interacting proteins - From biogenesis to synaptic plasticity. Neuropharmacology 2021; 197:108709. [PMID: 34271020 DOI: 10.1016/j.neuropharm.2021.108709] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/19/2021] [Accepted: 07/08/2021] [Indexed: 12/19/2022]
Abstract
AMPA-type glutamate receptors mediate the majority of excitatory synaptic transmission in the central nervous system. Their signaling properties and abundance at synapses are both crucial determinants of synapse efficacy and plasticity, and are therefore under sophisticated control. Unique to this ionotropic glutamate receptor (iGluR) is the abundance of interacting proteins that contribute to its complex regulation. These include transient interactions with the receptor cytoplasmic tail as well as the N-terminal domain locating to the synaptic cleft, both of which are involved in AMPAR trafficking and receptor stabilization at the synapse. Moreover, an array of transmembrane proteins operate as auxiliary subunits that in addition to receptor trafficking and stabilization also substantially impact AMPAR gating and pharmacology. Here, we provide an overview of the catalogue of AMPAR interacting proteins, and how they contribute to the complex biology of this central glutamate receptor.
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Affiliation(s)
- Peter M Matthews
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Alexandra Pinggera
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Domen Kampjut
- 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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8
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van Gelder CAGH, Altelaar M. Neuroproteomics of the Synapse: Subcellular Quantification of Protein Networks and Signaling Dynamics. Mol Cell Proteomics 2021; 20:100087. [PMID: 33933679 PMCID: PMC8167277 DOI: 10.1016/j.mcpro.2021.100087] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 01/21/2023] Open
Abstract
One of the most fascinating features of the brain is its ability to adapt to its surroundings. Synaptic plasticity, the dynamic mechanism of functional and structural alterations in synaptic strength, is essential for brain functioning and underlies a variety of processes such as learning and memory. Although the molecular mechanisms underlying such rapid plasticity are not fully understood, a consensus exists on the important role of proteins. The study of these neuronal proteins using neuroproteomics has increased rapidly in the last decades, and advancements in MS-based proteomics have broadened our understanding of neuroplasticity exponentially. In this review, we discuss the trends in MS-based neuroproteomics for the study of synaptic protein-protein interactions and protein signaling dynamics, with a focus on sample types, different labeling and enrichment approaches, and data analysis and interpretation. We highlight studies from the last 5 years, with a focus on synapse structure, composition, functioning, or signaling and finally discuss some recent developments that could further advance the field of neuroproteomics.
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Affiliation(s)
- Charlotte A G H van Gelder
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands; Netherlands Proteomics Center, Utrecht, The Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands; Netherlands Proteomics Center, Utrecht, The Netherlands.
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9
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Carrillo E, Shaikh SA, Berka V, Durham RJ, Litwin DB, Lee G, MacLean DM, Nowak LM, Jayaraman V. Mechanism of modulation of AMPA receptors by TARP-γ8. J Gen Physiol 2021; 152:jgp.201912451. [PMID: 31748249 PMCID: PMC7034100 DOI: 10.1085/jgp.201912451] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 11/04/2019] [Indexed: 01/24/2023] Open
Abstract
Using single-channel recordings and single-molecule FRET, Carrillo et al. show that resensitization of α-amino-5-methyl-3-hydroxy-4-isoxazole propionate receptors by the regulatory protein γ8 is characterized by transitions to high conductance levels associated with tighter conformational coupling similar to those seen in the presence of cyclothiazide. Fast excitatory synaptic transmission in the mammalian central nervous system is mediated by glutamate-activated α-amino-5-methyl-3-hydroxy-4-isoxazole propionate (AMPA) receptors. In neurons, AMPA receptors coassemble with transmembrane AMPA receptor regulatory proteins (TARPs). Assembly with TARP γ8 alters the biophysical properties of the receptor, producing resensitization currents in the continued presence of glutamate. Using single-channel recordings, we show that under resensitizing conditions, GluA2 AMPA receptors primarily transition to higher conductance levels, similar to activation of the receptors in the presence of cyclothiazide, which stabilizes the open state. To study the conformation associated with these states, we have used single-molecule FRET and show that this high-conductance state exhibits tighter coupling between subunits in the extracellular parts of the receptor. Furthermore, the dwell times for the transition from the tightly coupled state to the decoupled states correlate to longer open durations of the channels, thus correlating conformation and function at the single-molecule level.
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Affiliation(s)
- Elisa Carrillo
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX.,E. Carrillo and S.A. Shaikh contributed equally to this work and are listed in alphabetical order
| | - Sana A Shaikh
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX.,E. Carrillo and S.A. Shaikh contributed equally to this work and are listed in alphabetical order
| | - Vladimir Berka
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX
| | - Ryan J Durham
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX.,MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX
| | - Douglas B Litwin
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX.,MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX
| | - Garam Lee
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX
| | - David M MacLean
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY
| | - Linda M Nowak
- Department of Molecular Medicine, Cornell University, Ithaca, NY
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX.,MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX
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10
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Minehart JA, Speer CM. A Picture Worth a Thousand Molecules-Integrative Technologies for Mapping Subcellular Molecular Organization and Plasticity in Developing Circuits. Front Synaptic Neurosci 2021; 12:615059. [PMID: 33469427 PMCID: PMC7813761 DOI: 10.3389/fnsyn.2020.615059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022] Open
Abstract
A key challenge in developmental neuroscience is identifying the local regulatory mechanisms that control neurite and synaptic refinement over large brain volumes. Innovative molecular techniques and high-resolution imaging tools are beginning to reshape our view of how local protein translation in subcellular compartments drives axonal, dendritic, and synaptic development and plasticity. Here we review recent progress in three areas of neurite and synaptic study in situ-compartment-specific transcriptomics/translatomics, targeted proteomics, and super-resolution imaging analysis of synaptic organization and development. We discuss synergies between sequencing and imaging techniques for the discovery and validation of local molecular signaling mechanisms regulating synaptic development, plasticity, and maintenance in circuits.
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Affiliation(s)
| | - Colenso M. Speer
- Department of Biology, University of Maryland, College Park, MD, United States
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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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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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Jacobi E, von Engelhardt J. AMPA receptor complex constituents: Control of receptor assembly, membrane trafficking and subcellular localization. Mol Cell Neurosci 2018; 91:67-75. [DOI: 10.1016/j.mcn.2018.05.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 11/29/2022] Open
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Regulation of AMPA receptor trafficking and exit from the endoplasmic reticulum. Mol Cell Neurosci 2018; 91:3-9. [PMID: 29545119 DOI: 10.1016/j.mcn.2018.03.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 03/09/2018] [Accepted: 03/12/2018] [Indexed: 02/06/2023] Open
Abstract
A fundamental property of the brain is its ability to modify its function in response to its own activity. This ability for self-modification depends to a large extent on synaptic plasticity. It is now appreciated that for excitatory synapses, a significant part of synaptic plasticity depends upon changes in the post synaptic response to glutamate released from nerve terminals. Modification of the post synaptic response depends, in turn, on changes in the abundances of AMPA receptors in the post synaptic membrane. In this review, we consider mechanisms of trafficking of AMPA receptors to and from synapses that take place in the early trafficking stages, starting in the endoplasmic reticulum (ER) and continuing into the secretory pathway. We consider mechanisms of AMPA receptor assembly in the ER, highlighting the role of protein synthesis and the selective properties of specific AMPA receptor subunits, as well as regulation of ER exit, including the roles of chaperones and accessory proteins and the incorporation of AMPA receptors into COPII vesicles. We consider these processes in the context of the mechanism of mGluR LTD and discuss a compelling role for the dendritic ER membrane that is found proximal to synapses. The review illustrates the important, yet little studied, contribution of the early stages of AMPA receptor trafficking to synaptic plasticity.
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Abstract
Ionotropic glutamate receptors (AMPA, NMDA, and kainate receptors) play a central role in excitatory glutamatergic signaling throughout the brain. As a result, functional changes, especially long-lasting forms of plasticity, have the potential to profoundly alter neuronal function and the expression of adaptive and pathological behaviors. Thus, alcohol-related adaptations in ionotropic glutamate receptors are of great interest, since they could promote excessive alcohol consumption, even after long-term abstinence. Alcohol- and drug-related adaptations in NMDARs have been recently reviewed, while less is known about kainate receptor adaptations. Thus, we focus here on functional changes in AMPARs, tetramers composed of GluA1-4 subunits. Long-lasting increases or decreases in AMPAR function, the so-called long-term potentiation or depression, have widely been considered to contribute to normal and pathological memory states. In addition, a great deal has been learned about the acute regulation of AMPARs by signaling pathways, scaffolding and auxiliary proteins, intracellular trafficking, and other mechanisms. One important common adaptation is a shift in AMPAR subunit composition from GluA2-containing, calcium-impermeable AMPARs (CIARs) to GluA2-lacking, calcium-permeable AMPARs (CPARs), which is observed under a broad range of conditions including intoxicant exposure or intake, stress, novelty, food deprivation, and ischemia. This shift has the potential to facilitate AMPAR currents, since CPARs have much greater single-channel currents than CIARs, as well as faster AMPAR activation kinetics (although with faster inactivation) and calcium-related activity. Many tools have been developed to interrogate particular aspects of AMPAR signaling, including compounds that selectively inhibit CPARs, raising exciting translational possibilities. In addition, recent studies have used transgenic animals and/or optogenetics to identify AMPAR adaptations in particular cell types and glutamatergic projections, which will provide critical information about the specific circuits that CPARs act within. Also, less is known about the specific nature of alcohol-related AMPAR adaptations, and thus we use other examples that illustrate more fully how particular AMPAR changes might influence intoxicant-related behavior. Thus, by identifying alcohol-related AMPAR adaptations, the specific molecular events that underlie them, and the cells and projections in which they occur, we hope to better inform the development of new therapeutic interventions for addiction.
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Frank RA, Grant SG. Supramolecular organization of NMDA receptors and the postsynaptic density. Curr Opin Neurobiol 2017; 45:139-147. [PMID: 28577431 PMCID: PMC5557338 DOI: 10.1016/j.conb.2017.05.019] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/02/2017] [Accepted: 05/15/2017] [Indexed: 01/21/2023]
Abstract
The postsynaptic density (PSD) of all vertebrate species share a highly complex proteome with ∼1000 conserved proteins that function as sophisticated molecular computational devices. Here, we review recent studies showing that this complexity can be understood in terms of the supramolecular organization of proteins, which self-assemble within a hierarchy of different length scales, including complexes, supercomplexes and nanodomains. We highlight how genetic and biochemical approaches in mice are being used to uncover the native molecular architecture of the synapse, revealing hitherto unknown molecular structures, including highly selective mechanisms for specifying the assembly of NMDAR-MAGUK supercomplexes. We propose there exists a logical framework that precisely dictates the subunit composition of synaptic complexes, supercomplexes, and nanodomains in vivo.
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Affiliation(s)
- René Aw Frank
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Seth Gn Grant
- Centre for Clinical Brain Sciences, University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, UK.
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Yin P, Xu H, Wang Q, Wang J, Yin L, Xu M, Xie Z, Liu W, Cao X. Overexpression of βCaMKII impairs behavioral flexibility and NMDAR-dependent long-term depression in the dentate gyrus. Neuropharmacology 2017; 116:270-287. [DOI: 10.1016/j.neuropharm.2016.12.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 11/17/2016] [Accepted: 12/15/2016] [Indexed: 12/13/2022]
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Abstract
While some autoimmune disorders remain extremely rare, others largely predominate the epidemiology of human autoimmunity. Notably, these include psoriasis, diabetes, vitiligo, thyroiditis, rheumatoid arthritis and multiple sclerosis. Thus, despite the quasi-infinite number of "self" antigens that could theoretically trigger autoimmune responses, only a limited set of antigens, referred here as superautoantigens, induce pathogenic adaptive responses. Several lines of evidence reviewed in this paper indicate that, irrespective of the targeted organ (e.g. thyroid, pancreas, joints, brain or skin), a significant proportion of superautoantigens are highly expressed in the synaptic compartment of the central nervous system (CNS). Such an observation applies notably for GAD65, AchR, ribonucleoproteins, heat shock proteins, collagen IV, laminin, tyrosine hydroxylase and the acetylcholinesterase domain of thyroglobulin. It is also argued that cognitive alterations have been described in a number of autoimmune disorders, including psoriasis, rheumatoid arthritis, lupus, Crohn's disease and autoimmune thyroiditis. Finally, the present paper points out that a great majority of the "incidental" autoimmune conditions notably triggered by neoplasms, vaccinations or microbial infections are targeting the synaptic or myelin compartments. On this basis, the concept of an immunological homunculus, proposed by Irun Cohen more than 25 years ago, is extended here in a model where physiological autoimmunity against brain superautoantigens confers both: i) a crucial evolutionary-determined advantage via cognition-promoting autoimmunity; and ii) a major evolutionary-determined vulnerability, leading to the emergence of autoimmune disorders in Homo sapiens. Moreover, in this theoretical framework, the so called co-development/co-evolution model, both the development (at the scale of an individual) and evolution (at the scale of species) of the antibody and T-cell repertoires are coupled to those of the neural repertoires (i.e. the distinct neuronal populations and synaptic circuits supporting cognitive and sensorimotor functions). Clinical implications and future experimental insights are also presented and discussed.
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Affiliation(s)
- Serge Nataf
- Bank of Tissues and Cells, Lyon University Hospital (Hospices Civils de Lyon), CarMeN Laboratory, INSERM 1060, INRA 1397, INSA Lyon, Université Claude Bernard Lyon-1, Lyon, F-69000, France
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Dieterich DC, Kreutz MR. Proteomics of the Synapse--A Quantitative Approach to Neuronal Plasticity. Mol Cell Proteomics 2016; 15:368-81. [PMID: 26307175 PMCID: PMC4739661 DOI: 10.1074/mcp.r115.051482] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 07/29/2015] [Indexed: 11/06/2022] Open
Abstract
The advances in mass spectrometry based proteomics in the past 15 years have contributed to a deeper appreciation of protein networks and the composition of functional synaptic protein complexes. However, research on protein dynamics underlying core mechanisms of synaptic plasticity in brain lag far behind. In this review, we provide a synopsis on proteomic research addressing various aspects of synaptic function. We discuss the major topics in the study of protein dynamics of the chemical synapse and the limitations of current methodology. We highlight recent developments and the future importance of multidimensional proteomics and metabolic labeling. Finally, emphasis is given on the conceptual framework of modern proteomics and its current shortcomings in the quest to gain a deeper understanding of synaptic plasticity.
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Affiliation(s)
- Daniela C Dieterich
- From the ‡Institute for Pharmacology and Toxicology, Otto-von-Guericke University Magdeburg, Germany; Research Group Neuralomics, Leibniz Institute for Neurobiology Magdeburg, Germany; ¶Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
| | - Michael R Kreutz
- §RG Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; ¶Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
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Lee K, Goodman L, Fourie C, Schenk S, Leitch B, Montgomery JM. AMPA Receptors as Therapeutic Targets for Neurological Disorders. ION CHANNELS AS THERAPEUTIC TARGETS, PART A 2016; 103:203-61. [DOI: 10.1016/bs.apcsb.2015.10.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Han J, Wu P, Wang F, Chen J. S-palmitoylation regulates AMPA receptors trafficking and function: a novel insight into synaptic regulation and therapeutics. Acta Pharm Sin B 2015; 5:1-7. [PMID: 26579419 PMCID: PMC4629138 DOI: 10.1016/j.apsb.2014.12.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 12/05/2014] [Accepted: 12/09/2014] [Indexed: 01/11/2023] Open
Abstract
Glutamate acting on AMPA-type ionotropic glutamate receptor (AMPAR) mediates the majority of fast excitatory synaptic transmission in the mammalian central nervous system. Dynamic regulation of AMPAR by post-translational modifications is one of the key elements that allow the nervous system to adapt to environment stimulations. S-palmitoylation, an important lipid modification by post-translational addition of a long-chain fatty acid to a cysteine residue, regulates AMPA receptor trafficking, which dynamically affects multiple fundamental brain functions, such as learning and memory. In vivo, S-palmitoylation is controlled by palmitoyl acyl transferases and palmitoyl thioesterases. In this review, we highlight advances in the mechanisms for dynamic AMPA receptors palmitoylation, and discuss how palmitoylation affects AMPA receptors function at synapses in recent years. Pharmacological regulation of S-palmitoylation may serve as a novel therapeutic strategy for neurobiological diseases.
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Key Words
- 17-ODYA, 17-octadecynoic acid
- ABE, acyl-biotinyl exchange
- ABP, AMPA receptor binding protein
- AD, Alzheimer׳s disease
- AKAP79/150, A-kinase anchoring protein 79/150
- AMPA receptors
- AMPAR, α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor
- APT1, acyl-protein thioesterase-1
- APT2, acyl-protein thioesterase-2
- CP-AMPARs, Ca2+-permeable AMPARs
- DHHC
- DHHC, aspartate-histidine-histidine-cysteine
- FMRP, fragile X mental retardation protein
- FXS, Fragile X syndrome
- GAP-43, growth associated protein-43
- GRIP, glutamate receptor interacting protein
- LTD, long-term depression
- LTP, long-term potentiation
- PATs, palmitoyl acyl transferases
- PDZ, postsynaptic density-95/discs large/zona occludens-1
- PICK1, protein interacting with C-kinase 1
- PKA, protein kinase A
- PKC, protein kinase C
- PPT1, palmitoyl-protein thioesterase-1
- PSD-95, postsynaptic density-95
- Palmitoylation
- Ras, rat sarcoma
- SNAP-23, soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor protein-23
- Trafficking
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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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Gan Q, Salussolia CL, Wollmuth LP. Assembly of AMPA receptors: mechanisms and regulation. J Physiol 2014; 593:39-48. [PMID: 25556786 DOI: 10.1113/jphysiol.2014.273755] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 07/01/2014] [Indexed: 12/16/2022] Open
Abstract
AMPA receptors (AMPARs) play a critical role in excitatory glutamatergic neurotransmission. The number and subunit composition of AMPARs at synapses determines the dynamics of fast glutamatergic signalling. Functional AMPARs on the cell surface are tetramers. Thus tetrameric assembly of AMPARs represents a promising target for modulating AMPAR-mediated signalling in health and disease. Multiple structural domains within the receptor influence AMPAR assembly. In a proposed model for AMPAR assembly, the amino-terminal domain underlies the formation of a dimer pool. The transmembrane domain facilitates the formation and enhances the stability of the tetramer. The ligand-binding domain influences assembly through a process referred to as 'domain swapping'. We propose that this core AMPAR assembly process could be regulated by neuronal signals and speculate on possible mechanisms for such regulation.
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Affiliation(s)
- Quan Gan
- Graduate Program in Neuroscience, Stony Brook University, Stony Brook, NY, USA; Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behaviour, Stony Brook University, Stony Brook, NY, USA
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Nomura K, Harada E, Sugase K, Shimamoto K. Solid-state NMR spectra of lipid-anchored proteins under magic angle spinning. J Phys Chem B 2014; 118:2405-13. [PMID: 24517164 DOI: 10.1021/jp4124106] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solid-state NMR is a promising tool for elucidating membrane-related biological phenomena. We achieved the measurement of high-resolution solid-state NMR spectra for a lipid-anchored protein embedded in lipid bilayers under magic angle spinning (MAS). To date, solid-state NMR measurements of lipid-anchored proteins have not been accomplished due to the difficulty in supplying sufficient amount of stable isotope labeled samples in the overexpression of lipid-anchored proteins requiring complex posttranslational modification. We designed a pseudo lipid-anchored protein in which the protein component was expressed in E. coli and attached to a chemically synthesized lipid-anchor mimic. Using two types of membranes, liposomes and bicelles, we demonstrated different types of insertion procedures for lipid-anchored protein into membranes. In the liposome sample, we were able to observe the cross-polarization and the (13)C-(13)C chemical shift correlation spectra under MAS, indicating that the liposome sample can be used to analyze molecular interactions using dipolar-based NMR experiments. In contrast, the bicelle sample showed sufficient quality of spectra through scalar-based experiments. The relaxation times and protein-membrane interaction were capable of being analyzed in the bicelle sample. These results demonstrated the applicability of two types of sample system to elucidate the roles of lipid-anchors in regulating diverse biological phenomena.
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Affiliation(s)
- Kaoru Nomura
- Bioorganic Research Institute, Suntory Foundation for Life Sciences , 1-1-1 Wakayamadai, Shimamoto-Cho, Mishima-Gun, Osaka 618-8503, Japan
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Xiong L, Wen Y, Miao X, Yang Z. NT5E and FcGBP as key regulators of TGF-1-induced epithelial-mesenchymal transition (EMT) are associated with tumor progression and survival of patients with gallbladder cancer. Cell Tissue Res 2013; 355:365-74. [PMID: 24310606 PMCID: PMC3921456 DOI: 10.1007/s00441-013-1752-1] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 10/31/2013] [Indexed: 11/28/2022]
Abstract
Epithelial–mesenchymal transitions (EMTs) are essential manifestations of epithelial cell plasticity during tumor progression. Transforming growth factor-β(TGF-β) modulates epithelial plasticity in tumor physiological contexts by inducing EMT, which is associated with the altered expression of genes. In the present study, we used DNA micro-array analysis to search for differentially expressed genes in the TGF-β1 induced gallbladder carcinoma cell line (GBC-SD cells), as compared with normal GBC-SD cells. We identified 225 differentially expressed genes, including 144 that were over-expressed and 81 that were under-expressed in the TGF-β1 induced GBC-SD cells. NT5E (CD73) is the most increased gene, while the Fc fragment of the IgG binding protein (FcGBP) is the most decreased gene. The expression patterns of these two genes in gallbladder adenocarcinoma and chronic cholecystitis tissue were consistent with the micro-array data. Immunochemistry and clinicopathological results showed that the expression of NT5E and FcGBP in gallbladder adenocarcinoma is an independent marker for evaluation of the disease progression, clinical biological behaviors and prognosis. The data from the current study indicate that differential NT5E and FcGBP expressions could be further evaluated as biomarkers for predicting survival of patients with gallbladder cancer and that NT5E and FcGBP could be promising targets in the control of gallbladder cancer progression.
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Affiliation(s)
- Li Xiong
- Research Laboratory of Hepatobiliary Diseases, Second Xiangya Hospital, Central South University, 139# Middle Renmin road, Changsha, Hunan, 410011, China
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AMPA receptor/TARP stoichiometry visualized by single-molecule subunit counting. Proc Natl Acad Sci U S A 2013; 110:5163-8. [PMID: 23479622 DOI: 10.1073/pnas.1218765110] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Members of the transmembrane AMPA receptor-regulatory protein (TARP) family modulate AMPA receptor (AMPA-R) trafficking and function. AMPA-Rs consist of four pore-forming subunits. Previous studies show that TARPs are an integral part of the AMPA-R complex, acting as accessory subunits for mature receptors in vivo. The TARP/AMPA-R stoichiometry was previously measured indirectly and found to be variable and dependent on TARP expression level, with at most four TARPs associated with each AMPA-R complex. Here, we use a single-molecule technique in live cells that selectively images proteins located in the plasma membrane to directly count the number of TARPs associated with each AMPA-R complex. Although individual GFP-tagged TARP subunits are observed as freely diffusing fluorescent spots on the surface of Xenopus laevis oocytes when expressed alone, coexpression with AMPA-R-mCherry immobilizes the stargazin-GFP spots at sites of AMPA-R-mCherry, consistent with complex formation. We determined the number of TARP molecules associated with each AMPA-R by counting bleaching steps for three different TARP family members: γ-2, γ-3, and γ-4. We confirm that the TARP/AMPA-R stoichiometry depends on TARP expression level and discover that the maximum number of TARPs per AMPA-R complex falls into two categories: up to four γ-2 or γ-3 subunits, but rarely above two for γ-4 subunit. This unexpected AMPA-R/TARP stoichiometry difference has important implications for the assembly and function of TARP/AMPA-R complexes.
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27
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Sumioka A. Auxiliary subunits provide new insights into regulation of AMPA receptor trafficking. J Biochem 2013; 153:331-7. [PMID: 23426437 DOI: 10.1093/jb/mvt015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Glutamate is a major excitatory neurotransmitter in the vertebrate brain. Among the ionotropic glutamate receptors, α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) glutamate receptors are the major receptors mediating excitatory fast synaptic transmission. AMPA receptors are also responsible for modifying synaptic strength through the regulation of their numbers at synapses. Their high regulatability, therefore, could contribute to the mechanisms of synaptic plasticity. The mechanisms regulating AMPA receptor trafficking have evoked great interest through the decades. Recent studies show that in the brain, AMPA receptors make complexes with transmembrane AMPA regulatory proteins (TARPs), which serve as auxiliary subunits. TARPs are required for AMPA receptor function and trafficking. After the initial discovery of TARPs, several other AMPA receptor auxiliary subunits were identified: CNIH-2, CNIH-3, CKAMP44, SynDIG1, SOL-1, SOL-2 and GSG-1L. This review discusses progress in identifying the role of auxiliary subunits in AMPA receptor trafficking.
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Affiliation(s)
- Akio Sumioka
- Department of Aging Neurobiology, National Center for Geriatrics and Gerontology, Morioka-cho Gengo 35, Oobu city, Aichi 474-8511, Japan.
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28
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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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Abstract
Synaptic transmission is amongst the most sophisticated and tightly controlled biological phenomena in higher eukaryotes. In the past few decades, tremendous progress has been made in our understanding of the molecular mechanisms underlying multiple facets of neurotransmission, both pre- and postsynaptically. Brought under the spotlight by pioneer studies in the areas of secretion and signal transduction, phosphoinositides and their metabolizing enzymes have been increasingly recognized as key protagonists in fundamental aspects of neurotransmission. Not surprisingly, dysregulation of phosphoinositide metabolism has also been implicated in synaptic malfunction associated with a variety of brain disorders. In the present chapter, we summarize current knowledge on the role of phosphoinositides at the neuronal synapse and highlight some of the outstanding questions in this research field.
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Affiliation(s)
- Samuel G Frere
- Department of Pathology and Cell Biology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University Medical Center, 630 West 168th Street, P&S 12-420C, 10032, New York, USA
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Synaptic Plasticity Regulated by Protein–Protein Interactions and Posttranslational Modifications. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 297:1-43. [DOI: 10.1016/b978-0-12-394308-8.00001-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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31
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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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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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Li D, Specht CG, Waites CL, Butler-Munro C, Leal-Ortiz S, Foote JW, Genoux D, Garner CC, Montgomery JM. SAP97 directs NMDA receptor spine targeting and synaptic plasticity. J Physiol 2011; 589:4491-510. [PMID: 21768261 DOI: 10.1113/jphysiol.2011.215566] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
SAP97 is a multidomain scaffold protein implicated in the forward trafficking and synaptic localization of NMDA- and AMPA-type glutamate receptors. Alternative splicing of SAP97 transcripts gives rise to palmitoylated αSAP97 and L27-domain containing βSAP97 isoforms that differentially regulate the subsynaptic localization of GluR1 subunits of AMPA receptors. Here, we examined whether SAP97 isoforms regulate the mechanisms underlying long-term potentiation (LTP) and depression (LTD) and find that both α- and β-forms of SAP97 impair LTP but enhance LTD via independent isoform-specific mechanisms. Live imaging of α- and βSAP97 revealed that the altered synaptic plasticity was not due to activity-dependent changes in SAP97 localization or exchange kinetics. However, by recording from pairs of synaptically coupled hippocampal neurons, we show that αSAP97 occludes LTP by enhancing the levels of postsynaptic AMPA receptors, while βSAP97 blocks LTP by reducing the synaptic localization of NMDA receptors. Examination of the surface pools of AMPA and NMDA receptors indicates that αSAP97 selectively regulates the synaptic pool of AMPA receptors, whereas βSAP97 regulates the extrasynaptic pools of both AMPA and NMDA receptors. Knockdown of βSAP97 increases the synaptic localization of both AMPA and NMDA receptors, showing that endogenous βSAP97 restricts glutamate receptor expression at excitatory synapses. This isoform-dependent differential regulation of synaptic versus extrasynaptic pools of glutamate receptors will determine how many receptors are available for the induction and the expression of synaptic plasticity. Our data support a model wherein SAP97 isoforms can regulate the ability of synapses to undergo plasticity by controlling the surface distribution of AMPA and NMDA receptors.
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Affiliation(s)
- Dong Li
- Centre for Brain Research and Department of Physiology, University of Auckland, New Zealand
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35
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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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Ghafari M, Falsafi SK, Hoeger H, Lubec G. Hippocampal levels of GluR1 and GluR2 complexes are modulated by training in the Multiple T-maze in C57BL/6J mice. Brain Struct Funct 2011; 217:353-62. [PMID: 21695503 DOI: 10.1007/s00429-011-0335-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 06/01/2011] [Indexed: 11/25/2022]
Abstract
A series of studies has shown the importance of AMPA-type glutamate receptors (AMPARs) for memory formation. The aim of the current study was to show whether GluR1 and GluR2 complexes rather than subunits in mouse hippocampus were involved in training in the multiple T-Maze (MTM). C57BL/6J mice were trained in the MTM and compared to yoked controls. 6 h following the completion of the fourth day training, mice were euthanized, hippocampi were taken and proteins extracted, run on blue native gels with subsequent immunoblotting with antibodies against mouse GluR1 and GluR2. On blue-native western blotting, GluR1 protein was represented by a single band at the apparent molecular weight of about 480 kDa probably indicating a tetrameric assembly. GluR2 protein was represented by a single band between apparent molecular weights of 480 and 720 kDa indicating a homo- or heteropolymer probably with other AMPAR or regulatory subunits. In mice trained in the MTM, protein levels for GluR1 were significantly increased while GluR2 levels were significantly decreased. On two-dimensional (2D) gel electrophoresis, the presence of GluR1 and GluR2 were identified by mass spectrometry, and 2D immunoblotting revealed several expression forms of these receptor subunits. Findings unequivocally show that GluR1 and GluR2 complexes are linked to training in the MTM in C57BL/6J mice. These results may not only form the basis for studying receptor complexes rather than receptor subunits in memory formation or mechanisms of potential cognitive enhancers but represent a tool for investigations into pharmacological studies including the use of glutamate receptor agonists and antagonists.
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Affiliation(s)
- Maryam Ghafari
- Department of Pediatrics, Medical University of Vienna, Währinger Gürtel 18, 1090, Vienna, Austria
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Moritoh S, Tanaka KF, Jouhou H, Ikenaka K, Koizumi A. Organotypic tissue culture of adult rodent retina followed by particle-mediated acute gene transfer in vitro. PLoS One 2010; 5:e12917. [PMID: 20886064 PMCID: PMC2944845 DOI: 10.1371/journal.pone.0012917] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Accepted: 08/30/2010] [Indexed: 11/30/2022] Open
Abstract
Background Organotypic tissue culture of adult rodent retina with an acute gene transfer that enables the efficient introduction of variable transgenes would greatly facilitate studies into retinas of adult rodents as animal models. However, it has been a difficult challenge to culture adult rodent retina. The purpose of this present study was to develop organotypic tissue culture of adult rodent retina followed by particle-mediated acute gene transfer in vitro. Methodology/Principal Findings We established an interphase organotypic tissue culture for adult rat retinas (>P35 of age) which was optimized from that used for adult rabbit retinas. We implemented three optimizations: a greater volume of Ames' medium (>26 mL) per retina, a higher speed (constant 55 rpm) of agitation by rotary shaker, and a greater concentration (10%) of horse serum in the medium. We also successfully applied this method to adult mouse retina (>P35 of age). The organotypic tissue culture allowed us to keep adult rodent retina morphologically and structurally intact for at least 4 days. However, mouse retinas showed less viability after 4-day culture. Electrophysiologically, ganglion cells in cultured rat retina were able to generate action potentials, but exhibited less reliable light responses. After transfection of EGFP plasmids by particle-mediated acute gene transfer, we observed EGFP-expressing retinal ganglion cells as early as 1 day of culture. We also introduced polarized-targeting fusion proteins such as PSD95-GFP and melanopsin-EYFP (hOPN4-EYFP) into rat retinal ganglion cells. These fusion proteins were successfully transferred into appropriate locations on individual retinal neurons. Conclusions/Significance This organotypic culture method is largely applicable to rat retinas, but it can be also applied to mouse retinas with a caveat regarding cell viability. This method is quite flexible for use in acute gene transfection in adult rodent retina, replacing molecular biological bioassays that used to be conducted in isolated cultured cells.
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Affiliation(s)
- Satoru Moritoh
- Division of Correlative Physiology, National Institute for Physiological Sciences, Okazaki, Japan
| | - Kenji F. Tanaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Hiroshi Jouhou
- Drug Safety Research Laboratories, Astellas Pharma Inc., Osaka, Japan
| | - Kazuhiro Ikenaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
| | - Amane Koizumi
- Division of Correlative Physiology, National Institute for Physiological Sciences, Okazaki, Japan
- Section of Communications and Public Liaison, National Institute for Physiological Sciences, Okazaki, Japan
- Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Japan
- * E-mail:
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Traynelis SF, Wollmuth LP, McBain CJ, Menniti FS, Vance KM, Ogden KK, Hansen KB, Yuan H, Myers SJ, Dingledine R. Glutamate receptor ion channels: structure, regulation, and function. Pharmacol Rev 2010; 62:405-96. [PMID: 20716669 PMCID: PMC2964903 DOI: 10.1124/pr.109.002451] [Citation(s) in RCA: 2608] [Impact Index Per Article: 186.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
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Affiliation(s)
- Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322-3090, USA.
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Plk2 attachment to NSF induces homeostatic removal of GluA2 during chronic overexcitation. Nat Neurosci 2010; 13:1199-207. [PMID: 20802490 PMCID: PMC2947592 DOI: 10.1038/nn.2624] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 07/23/2010] [Indexed: 12/02/2022]
Abstract
Trafficking of AMPA receptors is important for many forms of synaptic plasticity. However, the link between activity and resulting synaptic alterations is not fully understood. Here, we identified a direct interaction between NSF, an ATPase involved in membrane fusion events and stabilization of surface AMPARs, and Plk2, an activity-inducible kinase that homeostatically decreases excitatory synapse number and strength. Plk2 disrupted interaction of NSF with the GluA2 subunit of AMPARs, promoting extensive loss of surface GluA2 in rat hippocampal neurons, greater association of GluA2 with adapter proteins PICK1 and GRIP1, and decreased synaptic AMPAR current. Plk2 engagement of NSF, but not Plk2 kinase activity, was required for this mechanism and occurred through a novel motif within Plk2 independent from canonical polo box interaction sites. These data reveal that heightened synaptic activity, acting through Plk2, leads to homeostatic decreases in surface AMPAR expression via the direct dissociation of NSF from GluA2.
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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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41
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Yamazaki M, Fukaya M, Hashimoto K, Yamasaki M, Tsujita M, Itakura M, Abe M, Natsume R, Takahashi M, Kano M, Sakimura K, Watanabe M. TARPs gamma-2 and gamma-7 are essential for AMPA receptor expression in the cerebellum. Eur J Neurosci 2010; 31:2204-20. [PMID: 20529126 DOI: 10.1111/j.1460-9568.2010.07254.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors require auxiliary subunits termed transmembrane AMPA receptor regulatory proteins (TARPs), which promote receptor trafficking to the cell surface and synapses and modulate channel pharmacology and gating. Of six TARPs, gamma-2 and gamma-7 are the two major TARPs expressed in the cerebellum. In the present study, we pursued their roles in synaptic expression of cerebellar AMPA receptors. In the cerebellar cortex, gamma-2 and gamma-7 were preferentially localized at various asymmetrical synapses. Using quantitative Western blot and immunofluorescence, we found severe reductions in GluA2 and GluA3 and mild reduction in GluA4 in gamma-2-knockout (KO) cerebellum, whereas GluA1 and GluA4 were moderately reduced in gamma-7-KO cerebellum. GluA2, GluA3 and GluA4 were further reduced in gamma-2/gamma-7 double-KO (DKO) cerebellum. The large losses of GluA2 and GluA3 in gamma-2-KO mice and further reductions in DKO mice were confirmed at all asymmetrical synapses examined with postembedding immunogold. Most notably, the GluA2 level in the postsynaptic density fraction, GluA2 labeling density at parallel fiber-Purkinje cell synapses, and AMPA receptor-mediated currents at climbing fiber-Purkinje cell synapses were all reduced to approximately 10% of the wild-type levels in DKO mice. On the other hand, the reduction in GluA4 in gamma-7-KO granular layer reflected its loss at mossy fiber-granule cell synapses, whereas that of GluA1 and GluA4 in gamma-7-KO molecular layer was caused, at least partly, by their loss in Bergmann glia. Therefore, gamma-2 and gamma-7 cooperatively promote synaptic expression of cerebellar AMPA receptors, and the latter also promotes glial expression.
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Affiliation(s)
- Maya Yamazaki
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
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Poglia L, Muller D, Nikonenko I. Ultrastructural modifications of spine and synapse morphology by SAP97. Hippocampus 2010; 21:990-8. [PMID: 20865734 DOI: 10.1002/hipo.20811] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2010] [Indexed: 01/01/2023]
Abstract
Synaptic scaffolding proteins from membrane-associated guanylate kinases (MAGUK) family are implicated in synapse formation and functioning. To better understand the role of one of the proteins of this family, SAP97, we studied with electron microscopy the effects of its overexpression on spine and synapse morphology in CA1 pyramidal neurons of rat organotypic hippocampal slice cultures. Dramatic spine enlargement induced by SAP97 overexpression was accompanied by marked morphological changes, with spines enwrapping and engulfing presynaptic terminals. The size and complexity of the PSD was also significantly increased. Similar to PSD-95, SAP97 promoted formation of multi-innervated spines (MIS). In addition, both MAGUK proteins induced multiple excitatory contacts on dendritic shafts suggesting a mechanism for shaft synapse formation. Formation of MIS and shaft synapses was blocked by the nitric oxide synthase (NOS) inhibitor L-NAME. Immunochemistry revealed that overexpression of SAP97 was associated with overexpression of PSD-95 and recruitment of nNOS to the synapse. These data provide evidence for both common and distinct structural alterations produced by overexpression of SAP97 and PSD-95 and demonstrate strong interactions between these two proteins to regulate contact formation through nitric oxide signaling.
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Affiliation(s)
- Lorenzo Poglia
- Department and Center of Neuroscience, Geneva University Medical Center, CH-1211 Geneva, Switzerland
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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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Li KW, Klemmer P, Smit AB. Interaction proteomics of synapse protein complexes. Anal Bioanal Chem 2010; 397:3195-202. [PMID: 20361179 PMCID: PMC2911543 DOI: 10.1007/s00216-010-3658-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 03/15/2010] [Accepted: 03/15/2010] [Indexed: 01/29/2023]
Abstract
The brain integrates complex types of information, and executes a wide range of physiological and behavioral processes. Trillions of tiny organelles, the synapses, are central to neuronal communication and information processing in the brain. Synaptic transmission involves an intricate network of synaptic proteins that forms the molecular machinery underlying transmitter release, activation, and modulation of transmitter receptors and signal transduction cascades. These processes are dynamically regulated and underlie neuroplasticity, crucial to learning and memory formation. In recent years, interaction proteomics has increasingly been used to elucidate the constituents of synaptic protein complexes. Unlike classic hypothesis-based assays, interaction proteomics detects both known and novel interactors without bias. In this trend article, we focus on the technical aspects of recent proteomics to identify synapse protein complexes, and the complementary methods used to verify the protein–protein interaction. Moreover, we discuss the experimental feasibility of performing global analysis of the synapse protein interactome.
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Affiliation(s)
- Ka Wan Li
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
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Disruption of LGI1-linked synaptic complex causes abnormal synaptic transmission and epilepsy. Proc Natl Acad Sci U S A 2010; 107:3799-804. [PMID: 20133599 DOI: 10.1073/pnas.0914537107] [Citation(s) in RCA: 224] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Epilepsy is a devastating and poorly understood disease. Mutations in a secreted neuronal protein, leucine-rich glioma inactivated 1 (LGI1), were reported in patients with an inherited form of human epilepsy, autosomal dominant partial epilepsy with auditory features (ADPEAF). Here, we report an essential role of LGI1 as an antiepileptogenic ligand. We find that loss of LGI1 in mice (LGI1(-/-)) causes lethal epilepsy, which is specifically rescued by the neuronal expression of LGI1 transgene, but not LGI3. Moreover, heterozygous mice for the LGI1 mutation (LGI1(+/-)) show lowered seizure thresholds. Extracellularly secreted LGI1 links two epilepsy-related receptors, ADAM22 and ADAM23, in the brain and organizes a transsynaptic protein complex that includes presynaptic potassium channels and postsynaptic AMPA receptor scaffolds. A lack of LGI1 disrupts this synaptic protein connection and selectively reduces AMPA receptor-mediated synaptic transmission in the hippocampus. Thus, LGI1 may serve as a major determinant of brain excitation, and the LGI1 gene-targeted mouse provides a good model for human epilepsy.
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46
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Glutamatergic Reinnervation and Assembly of Glutamatergic Synapses in Adult Rat Skeletal Muscle Occurs at Cholinergic Endplates. J Neuropathol Exp Neurol 2009; 68:1103-15. [PMID: 19918122 DOI: 10.1097/nen.0b013e3181b7bfc8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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47
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Li X, Xie C, Jin Q, Liu M, He Q, Cao R, Lin Y, Li J, Li Y, Chen P, Liang S. Proteomic screen for multiprotein complexes in synaptic plasma membrane from rat hippocampus by blue native gel electrophoresis and tandem mass spectrometry. J Proteome Res 2009; 8:3475-86. [PMID: 19432478 DOI: 10.1021/pr900101d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Neuronal synapses are specialized sites for information exchange between neurons. Many diseases, such as addiction and mood disorders, likely result from altered expression of synaptic proteins, or altered formation of synaptic complexes involved in neurotransmission or neuroplasticity. A detailed description of native multiprotein complexes in synaptic plasma membranes (PM) is therefore essential for understanding biological mechanisms and disease processes. For the first time in this study, two-dimensional Blue Native/SDS-PAGE electrophoresis, combined with tandem mass spectrometry, was used to screen multiprotein complexes in synaptic plasma membranes from rat hippocampus. As a result, 514 unique proteins were identified, of which 36% were integral membrane proteins. In addition, 19 potentially novel and known heterooligomeric multiprotein complexes were found, such as the SNARE and ATPase complexes. A potentially novel protein complex, involving syntaxin, synapsin I and Na+/K+ ATPase alpha-1, was further confirmed by co-immunoprecipitation and immunofluorescence staining. As demonstrated here, Blue Native-PAGE is a powerful tool for the separation of hydrophobic membrane proteins. The combination of Blue Native-PAGE and mass spectrometry could systematically identify multiprotein complexes.
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Affiliation(s)
- Xuanwen Li
- Key Laboratory of Protein Chemistry and Developmental Biology of Education Committee, College of Life Sciences, Hunan Normal University, Changsha, 410081, PR China
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48
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Sun H, Swaim A, Herrera JE, Becker D, Becker L, Srivastava K, Thompson LE, Shero MR, Perez-Tamayo A, Suktitipat B, Mathias R, Contractor A, Faraday N, Morrell CN. Platelet kainate receptor signaling promotes thrombosis by stimulating cyclooxygenase activation. Circ Res 2009; 105:595-603. [PMID: 19679838 PMCID: PMC2771168 DOI: 10.1161/circresaha.109.198861] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
RATIONALE Glutamate is a major signaling molecule that binds to glutamate receptors including the ionotropic glutamate receptors; kainate (KA) receptor (KAR), the N-methyl-d-aspartate receptor, and the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor. Each is well characterized in the central nervous system, but glutamate has important signaling roles in peripheral tissues as well, including a role in regulating platelet function. OBJECTIVE Our previous work has demonstrated that glutamate is released by platelets in high concentrations within a developing thrombus and increases platelet activation and thrombosis. We now show that platelets express a functional KAR that drives increased agonist induced platelet activation. METHODS AND RESULTS KAR induced increase in platelet activation is in part the result of activation of platelet cyclooxygenase in a mitogen-activated protein kinase-dependent manner. Platelets derived from KAR subunit knockout mice (GluR6(-/-)) are resistant to KA effects and have a prolonged time to thrombosis in vivo. Importantly, we have also identified polymorphisms in KAR subunits that are associated with phenotypic changes in platelet function in a large group of whites and blacks. CONCLUSIONS Our data demonstrate that glutamate regulation of platelet activation is in part cyclooxygenase-dependent and suggest that the KAR is a novel antithrombotic target.
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Affiliation(s)
- Henry Sun
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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S-nitrosylation of stargazin regulates surface expression of AMPA-glutamate neurotransmitter receptors. Proc Natl Acad Sci U S A 2009; 106:16440-5. [PMID: 19805317 DOI: 10.1073/pnas.0908949106] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Synaptic plasticity is mediated by changes in the surface expression of AMPA receptors (AMPARs). Stargazin and related transmembrane AMPAR regulatory proteins have emerged as the principal regulators of AMPAR surface expression. Here, we show in heterologous cells and primary neurons that stargazin is physiologically S-nitrosylated, resulting in increased surface expression. S-nitrosylation of stargazin increases binding to the AMPAR subunit GluR1, causing increased surface expression of the AMPAR. NMDAR stimulation, well known to activate neuronal nitric oxide synthase, increases both nitrosylation of stargazin and its binding to AMPAR. Thus, S-nitrosylation of stargazin is a physiologic regulator of AMPAR surface expression.
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Noritake J, Fukata Y, Iwanaga T, Hosomi N, Tsutsumi R, Matsuda N, Tani H, Iwanari H, Mochizuki Y, Kodama T, Matsuura Y, Bredt DS, Hamakubo T, Fukata M. Mobile DHHC palmitoylating enzyme mediates activity-sensitive synaptic targeting of PSD-95. ACTA ACUST UNITED AC 2009; 186:147-60. [PMID: 19596852 PMCID: PMC2712995 DOI: 10.1083/jcb.200903101] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Protein palmitoylation is the most common posttranslational lipid modification; its reversibility mediates protein shuttling between intracellular compartments. A large family of DHHC (Asp-His-His-Cys) proteins has emerged as protein palmitoyl acyltransferases (PATs). However, mechanisms that regulate these PATs in a physiological context remain unknown. In this study, we efficiently monitored the dynamic palmitate cycling on synaptic scaffold PSD-95. We found that blocking synaptic activity rapidly induces PSD-95 palmitoylation and mediates synaptic clustering of PSD-95 and associated AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)-type glutamate receptors. A dendritically localized DHHC2 but not the Golgi-resident DHHC3 mediates this activity-sensitive palmitoylation. Upon activity blockade, DHHC2 translocates to the postsynaptic density to transduce this effect. These data demonstrate that individual DHHC members are differentially regulated and that dynamic recruitment of protein palmitoylation machinery enables compartmentalized regulation of protein trafficking in response to extracellular signals.
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Affiliation(s)
- Jun Noritake
- Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Aichi, Japan
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