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Morise J, Suzuki KGN, Kitagawa A, Wakazono Y, Takamiya K, Tsunoyama TA, Nemoto YL, Takematsu H, Kusumi A, Oka S. AMPA receptors in the synapse turnover by monomer diffusion. Nat Commun 2019; 10:5245. [PMID: 31748519 PMCID: PMC6868016 DOI: 10.1038/s41467-019-13229-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 10/28/2019] [Indexed: 12/27/2022] Open
Abstract
The number and subunit compositions of AMPA receptors (AMPARs), hetero- or homotetramers composed of four subunits GluA1–4, in the synapse is carefully tuned to sustain basic synaptic activity. This enables stimulation-induced synaptic plasticity, which is central to learning and memory. The AMPAR tetramers have been widely believed to be stable from their formation in the endoplasmic reticulum until their proteolytic decomposition. However, by observing GluA1 and GluA2 at the level of single molecules, we find that the homo- and heterotetramers are metastable, instantaneously falling apart into monomers, dimers, or trimers (in 100 and 200 ms, respectively), which readily form tetramers again. In the dendritic plasma membrane, GluA1 and GluA2 monomers and dimers are far more mobile than tetramers and enter and exit from the synaptic regions. We conclude that AMPAR turnover by lateral diffusion, essential for sustaining synaptic function, is largely done by monomers of AMPAR subunits, rather than preformed tetramers. The mechanisms regulating the turnover of the AMPARs in the synapse, which is critically important to sustain basic synaptic activity, remains unclear. In this study, authors used single-molecule imaging techniques to demonstrate that AMPAR tetramers are not stable entities and readily fall apart to dimers and monomers that could reform to tetramers at the synapse, and that rapidly diffusing monomers in the plasma membrane are primarily responsible for the AMPAR turnover in the synapse.
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Affiliation(s)
- Jyoji Morise
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Kenichi G N Suzuki
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, 501-1193, Japan. .,Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan.
| | - Ayaka Kitagawa
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Yoshihiko Wakazono
- Department of Integrative Physiology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Kogo Takamiya
- Department of Integrative Physiology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Taka A Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan
| | - Yuri L Nemoto
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan
| | - Hiromu Takematsu
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.,Department of Molecular Cell Biology, Faculty of Medical Technology, Graduate School of Health Sciences, Fujita Health University, Aichi, 470-1192, Japan
| | - Akihiro Kusumi
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan. .,Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan.
| | - Shogo Oka
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.
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Plested AJR. Single-Channel Recording of Ligand-Gated Ion Channels. Cold Spring Harb Protoc 2016; 2016:2016/8/pdb.top087239. [PMID: 27480725 DOI: 10.1101/pdb.top087239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Single-channel recordings reveal the microscopic properties of individual ligand-gated ion channels. Such recordings contain much more information than measurements of ensemble behavior and can yield structural and functional information about the receptors that participate in fast synaptic transmission in the brain. With a little care, a standard patch-clamp electrophysiology setup can be adapted for single-channel recording in a matter of hours. Thenceforth, it is a realistic aim to record single-molecule activity with microsecond resolution from arbitrary cell types, including cell lines and neurons.
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Affiliation(s)
- Andrew J R Plested
- Leibniz-Institut für Molekulare Pharmakologie (FMP), 13125 Berlin, Germany; NeuroCure, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
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Abstract
Highlighted in this unit are issues that should be considered when recording glutamate receptors at the single-channel level, including some commonly encountered problems and their remedies. "UNIT 11.17, Single-Channel Analysis of Glutamate Receptors" describes analysis techniques used to characterize the recorded single-channel properties.
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Affiliation(s)
- Chris Shelley
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London, WC1E 6BT, United Kingdom
- Present address: Department of Biology, Franklin and Marshall College, Lancaster, 17604, Pennsylvania
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Möykkynen T, Coleman SK, Semenov A, Keinänen K. The N-terminal domain modulates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor desensitization. J Biol Chem 2014; 289:13197-205. [PMID: 24652293 DOI: 10.1074/jbc.m113.526301] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
AMPA receptors are tetrameric glutamate-gated ion channels that mediate fast synaptic neurotransmission in mammalian brain. Their subunits contain a two-lobed N-terminal domain (NTD) that comprises over 40% of the mature polypeptide. The NTD is not obligatory for the assembly of tetrameric receptors, and its functional role is still unclear. By analyzing full-length and NTD-deleted GluA1-4 AMPA receptors expressed in HEK 293 cells, we found that the removal of the NTD leads to a significant reduction in receptor transport to the plasma membrane, a higher steady state-to-peak current ratio of glutamate responses, and strongly increased sensitivity to glutamate toxicity in cell culture. Further analyses showed that NTD-deleted receptors display both a slower onset of desensitization and a faster recovery from desensitization of agonist responses. Our results indicate that the NTD promotes the biosynthetic maturation of AMPA receptors and, for membrane-expressed channels, enhances the stability of the desensitized state. Moreover, these findings suggest that interactions of the NTD with extracellular/synaptic ligands may be able to fine-tune AMPA receptor-mediated responses, in analogy with the allosteric regulatory role demonstrated for the NTD of NMDA receptors.
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Affiliation(s)
- Tommi Möykkynen
- From the Division of Biochemistry and Biotechnology, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
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