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Ning L, Shen R, Xie B, Jiang Y, Geng X, Dong W. AMPA receptors in Alzheimer disease: Pathological changes and potential therapeutic targets. J Neuropathol Exp Neurol 2024:nlae093. [PMID: 39235983 DOI: 10.1093/jnen/nlae093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2024] Open
Abstract
Alzheimer disease (AD) is a prevalent neurodegenerative disorder that affects synapses and leads to progressive cognitive decline. The role of N-methyl-D-aspartic acid (NMDA) receptors in the pathogenesis of AD is well-established as they contribute to excitotoxicity and neurodegeneration in the pathological process of extrasynaptic glutamate concentration. However, the therapeutic potential of the NMDA receptor antagonist memantine in rescuing synaptic damage is limited. Research indicates that α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors also play a significant role in AD. Abnormal transcription, expression, and localization of AMPA receptors lead to synaptic dysfunction and damage, contributing to early cognitive impairment in AD patients. Understanding the impact of AMPA receptors on AD pathogenesis and exploring the potential for the development of AMPA receptor-targeting drugs are crucial. This review aims to consolidate recent research findings on AMPA receptors in AD, elucidate the current state of AMPA receptor research and lay the foundation for future basic research and drug development.
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Affiliation(s)
- Luying Ning
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Rongjing Shen
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Bingqing Xie
- Laboratory of Neurological Diseases and Brain Function, Institute of Epigenetics and Brain Science, Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Yong Jiang
- Laboratory of Neurological Diseases and Brain Function, Institute of Epigenetics and Brain Science, Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Xiaoqi Geng
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
- Department of Neurosurgery, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Wei Dong
- Key Laboratory of Medical Electrophysiology, Ministry of Education & Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
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Wong VC, Houlihan PR, Liu H, Walpita D, DeSantis MC, Liu Z, O'Shea EK. Plasticity-induced actin polymerization in the dendritic shaft regulates intracellular AMPA receptor trafficking. eLife 2024; 13:e80622. [PMID: 39146380 PMCID: PMC11326776 DOI: 10.7554/elife.80622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 07/09/2024] [Indexed: 08/17/2024] Open
Abstract
AMPA-type receptors (AMPARs) are rapidly inserted into synapses undergoing plasticity to increase synaptic transmission, but it is not fully understood if and how AMPAR-containing vesicles are selectively trafficked to these synapses. Here, we developed a strategy to label AMPAR GluA1 subunits expressed from their endogenous loci in cultured rat hippocampal neurons and characterized the motion of GluA1-containing vesicles using single-particle tracking and mathematical modeling. We find that GluA1-containing vesicles are confined and concentrated near sites of stimulation-induced structural plasticity. We show that confinement is mediated by actin polymerization, which hinders the active transport of GluA1-containing vesicles along the length of the dendritic shaft by modulating the rheological properties of the cytoplasm. Actin polymerization also facilitates myosin-mediated transport of GluA1-containing vesicles to exocytic sites. We conclude that neurons utilize F-actin to increase vesicular GluA1 reservoirs and promote exocytosis proximal to the sites of synaptic activity.
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Affiliation(s)
- Victor C Wong
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Patrick R Houlihan
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Hui Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Deepika Walpita
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Michael C DeSantis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Erin K O'Shea
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
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3
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Harris KM, Kuwajima M, Flores JC, Zito K. Synapse-specific structural plasticity that protects and refines local circuits during LTP and LTD. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230224. [PMID: 38853547 DOI: 10.1098/rstb.2023.0224] [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: 10/17/2023] [Accepted: 01/05/2024] [Indexed: 06/11/2024] Open
Abstract
Synapses form trillions of connections in the brain. Long-term potentiation (LTP) and long-term depression (LTD) are cellular mechanisms vital for learning that modify the strength and structure of synapses. Three-dimensional reconstruction from serial section electron microscopy reveals three distinct pre- to post-synaptic arrangements: strong active zones (AZs) with tightly docked vesicles, weak AZs with loose or non-docked vesicles, and nascent zones (NZs) with a postsynaptic density but no presynaptic vesicles. Importantly, LTP can be temporarily saturated preventing further increases in synaptic strength. At the onset of LTP, vesicles are recruited to NZs, converting them to AZs. During recovery of LTP from saturation (1-4 h), new NZs form, especially on spines where AZs are most enlarged by LTP. Sentinel spines contain smooth endoplasmic reticulum (SER), have the largest synapses and form clusters with smaller spines lacking SER after LTP recovers. We propose a model whereby NZ plasticity provides synapse-specific AZ expansion during LTP and loss of weak AZs that drive synapse shrinkage during LTD. Spine clusters become functionally engaged during LTP or disassembled during LTD. Saturation of LTP or LTD probably acts to protect recently formed memories from ongoing plasticity and may account for the advantage of spaced over massed learning. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.
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Affiliation(s)
- Kristen M Harris
- Department of Neuroscience and Center for Learning and Memory, The University of Texas at Austin , Austin, TX 78712, USA
| | - Masaaki Kuwajima
- Department of Neuroscience and Center for Learning and Memory, The University of Texas at Austin , Austin, TX 78712, USA
| | - Juan C Flores
- Center for Neuroscience, University of California , Davis, CA 95618, USA
| | - Karen Zito
- Center for Neuroscience, University of California , Davis, CA 95618, USA
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Dashkova AS, Kovalev VI, Chaplygina AV, Zhdanova DY, Bobkova NV. Unique Properties of Synaptosomes and Prospects for Their Use for the Treatment of Alzheimer's Disease. BIOCHEMISTRY. BIOKHIMIIA 2024; 89:1031-1044. [PMID: 38981699 DOI: 10.1134/s0006297924060051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/21/2024] [Accepted: 03/23/2024] [Indexed: 07/11/2024]
Abstract
Alzheimer's disease (AD) is a severe neurodegenerative condition affecting millions worldwide. Prevalence of AD correlates with increased life expectancy and aging population in the developed countries. Considering that AD is a multifactorial disease involving various pathological processes such as synaptic dysfunction, neuroinflammation, oxidative stress, and improper protein folding, a comprehensive approach targeting multiple pathways may prove effective in slowing the disease progression. Cellular therapy and its further development in the form of cell vesicle and particularly mitochondrial transplantation represent promising approaches for treating neurodegeneration. The use of synaptosomes, due to uniqueness of their contents, could mark a new stage in the development of comprehensive therapies for neurodegenerative diseases, particularly AD. Synaptosomes contain unique memory mitochondria, which differ not only in size but also in functionality compared to the mitochondria in the neuronal soma. These synaptosomal mitochondria actively participate in cellular communication and signal transmission within synapses. Synaptosomes also contain other elements such as their own protein synthesis machinery, synaptic vesicles with neurotransmitters, synaptic adhesion molecules, and microRNAs - all crucial for synaptic transmission and, consequently, cognitive processes. Complex molecular ensemble ensures maintenance of the synaptic autonomy of mitochondria. Additionally, synaptosomes, with their affinity for neurons, can serve as an optimal platform for targeted drug delivery to nerve cells. This review discusses unique composition of synaptosomes, their capabilities and advantages, as well as limitations of their suggested use as therapeutic agents for treating neurodegenerative pathologies, particularly AD.
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Affiliation(s)
- Alla S Dashkova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Vladimir I Kovalev
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
| | - Alina V Chaplygina
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Daria Yu Zhdanova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | - Natalia V Bobkova
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
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5
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Sun C. Single-Molecule-Resolution Approaches in Synaptic Biology. J Phys Chem B 2024; 128:3061-3068. [PMID: 38513216 DOI: 10.1021/acs.jpcb.3c08026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Synapses between neurons are the primary loci for information transfer and storage in the brain. An individual neuron, alone, can make over 10000 synaptic contacts. It is, however, not easy to investigate what goes on locally within a synapse because many synaptic compartments are only a few hundred nanometers wide in size─close to the diffraction limit of light. To observe the biomolecular machinery and processes within synapses, in situ single-molecule techniques are emerging as powerful tools. Guided by important biological questions, this Perspective will highlight recent advances in using these techniques to obtain in situ measurements of synaptic molecules in three aspects: the cell-biological machinery within synapses, the synaptic architecture, and the synaptic neurotransmitter receptors. These advances showcase the increasing importance of single-molecule-resolution techniques for accessing subcellular biophysical and biomolecular information related to the brain.
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Affiliation(s)
- Chao Sun
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, 8000 Aarhus C, Denmark
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6
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Anderson MC, Levy AD, Dharmasri PA, Metzbower SR, Blanpied TA. Trans-synaptic molecular context of NMDA receptor nanodomains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.22.573055. [PMID: 38187545 PMCID: PMC10769418 DOI: 10.1101/2023.12.22.573055] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Tight coordination of the spatial relationships between protein complexes is required for cellular function. In neuronal synapses, many proteins responsible for neurotransmission organize into subsynaptic nanoclusters whose trans-cellular alignment modulates synaptic signal propagation. However, the spatial relationships between these proteins and NMDA receptors (NMDARs), which are required for learning and memory, remain undefined. Here, we mapped the relationship of key NMDAR subunits to reference proteins in the active zone and postsynaptic density using multiplexed super-resolution DNA-PAINT microscopy. GluN2A and GluN2B subunits formed nanoclusters with diverse configurations that, surprisingly, were not localized near presynaptic vesicle release sites marked by Munc13-1. However, a subset of presynaptic sites was configured to maintain NMDAR activation: these were internally denser, aligned with abundant PSD-95, and associated closely with specific NMDAR nanodomains. This work reveals a new principle regulating NMDAR signaling and suggests that synaptic functional architecture depends on assembly of multiprotein nanodomains whose interior construction is conditional on trans-cellular relationships.
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Affiliation(s)
- Michael C Anderson
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Aaron D Levy
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Poorna A Dharmasri
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, USA
- Current address: Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sarah R Metzbower
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Current address: Nikon Instruments Inc, Melville, NY, USA
| | - Thomas A Blanpied
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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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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8
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Tse D, Privitera L, Norton AC, Gobbo F, Spooner P, Takeuchi T, Martin SJ, Morris RGM. Cell-type-specific optogenetic stimulation of the locus coeruleus induces slow-onset potentiation and enhances everyday memory in rats. Proc Natl Acad Sci U S A 2023; 120:e2307275120. [PMID: 37931094 PMCID: PMC10655220 DOI: 10.1073/pnas.2307275120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 09/12/2023] [Indexed: 11/08/2023] Open
Abstract
Memory formation is typically divided into phases associated with encoding, storage, consolidation, and retrieval. The neural determinants of these phases are thought to differ. This study first investigated the impact of the experience of novelty in rats incurred at a different time, before or after, the precise moment of memory encoding. Memory retention was enhanced. Optogenetic activation of the locus coeruleus mimicked this enhancement induced by novelty, both when given before and after the moment of encoding. Optogenetic activation of the locus coeruleus also induced a slow-onset potentiation of field potentials in area CA1 of the hippocampus evoked by CA3 stimulation. Despite the locus coeruleus being considered a primarily noradrenergic area, both effects of such stimulation were blocked by the dopamine D1/D5 receptor antagonist SCH 23390. These findings substantiate and enrich the evidence implicating the locus coeruleus in cellular aspects of memory consolidation in hippocampus.
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Affiliation(s)
- Dorothy Tse
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
- Department of Psychology, Edge Hill University, OmskirkL39 4QP, United Kingdom
| | - Lucia Privitera
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
- School of Systems Medicine, University of Dundee, DundeeDD1 4HN, United Kingdom
- Barts and the London School of Medicine, Institute of Health Sciences Education, Queen Mary University of London Malta Campus, VictoriaVCT 2570, Malta
| | - Anna C. Norton
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
| | - Francesco Gobbo
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
| | - Patrick Spooner
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
| | - Tomonori Takeuchi
- Danish Research Institute of Translational Neuroscience, Nordic-European Molecular Biology Laboratory Partnership for Molecular Medicine, Aarhus University, Aarhus8000, Denmark
- Center for Proteins in Memory, Danish National Research Foundation, Department of Biomedicine, Aarhus University, Aarhus8000, Denmark
| | - Stephen J. Martin
- School of Systems Medicine, University of Dundee, DundeeDD1 4HN, United Kingdom
| | - Richard G. M. Morris
- Centre for Discovery Brain Sciences, Edinburgh Neuroscience, University of Edinburgh, EdinburghEH8 9JZ, United Kingdom
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Nicoll RA, Schulman H. Synaptic memory and CaMKII. Physiol Rev 2023; 103:2877-2925. [PMID: 37290118 PMCID: PMC10642921 DOI: 10.1152/physrev.00034.2022] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 04/26/2023] [Accepted: 04/30/2023] [Indexed: 06/10/2023] Open
Abstract
Ca2+/calmodulin-dependent protein kinase II (CaMKII) and long-term potentiation (LTP) were discovered within a decade of each other and have been inextricably intertwined ever since. However, like many marriages, it has had its up and downs. Based on the unique biochemical properties of CaMKII, it was proposed as a memory molecule before any physiological linkage was made to LTP. However, as reviewed here, the convincing linkage of CaMKII to synaptic physiology and behavior took many decades. New technologies were critical in this journey, including in vitro brain slices, mouse genetics, single-cell molecular genetics, pharmacological reagents, protein structure, and two-photon microscopy, as were new investigators attracted by the exciting challenge. This review tracks this journey and assesses the state of this marriage 40 years on. The collective literature impels us to propose a relatively simple model for synaptic memory involving the following steps that drive the process: 1) Ca2+ entry through N-methyl-d-aspartate (NMDA) receptors activates CaMKII. 2) CaMKII undergoes autophosphorylation resulting in constitutive, Ca2+-independent activity and exposure of a binding site for the NMDA receptor subunit GluN2B. 3) Active CaMKII translocates to the postsynaptic density (PSD) and binds to the cytoplasmic C-tail of GluN2B. 4) The CaMKII-GluN2B complex initiates a structural rearrangement of the PSD that may involve liquid-liquid phase separation. 5) This rearrangement involves the PSD-95 scaffolding protein, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), and their transmembrane AMPAR-regulatory protein (TARP) auxiliary subunits, resulting in an accumulation of AMPARs in the PSD that underlies synaptic potentiation. 6) The stability of the modified PSD is maintained by the stability of the CaMKII-GluN2B complex. 7) By a process of subunit exchange or interholoenzyme phosphorylation CaMKII maintains synaptic potentiation in the face of CaMKII protein turnover. There are many other important proteins that participate in enlargement of the synaptic spine or modulation of the steps that drive and maintain the potentiation. In this review we critically discuss the data underlying each of the steps. As will become clear, some of these steps are more firmly grounded than others, and we provide suggestions as to how the evidence supporting these steps can be strengthened or, based on the new data, be replaced. Although the journey has been a long one, the prospect of having a detailed cellular and molecular understanding of learning and memory is at hand.
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Affiliation(s)
- Roger A Nicoll
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California, United States
| | - Howard Schulman
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California, United States
- Panorama Research Institute, Sunnyvale, California, United States
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Ross MM, Aizenman E. GluA1-Shank3 interaction decreases in response to chronic neuronal depolarization. Neurosci Lett 2023; 809:137305. [PMID: 37210067 PMCID: PMC10330850 DOI: 10.1016/j.neulet.2023.137305] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/13/2023] [Accepted: 05/15/2023] [Indexed: 05/22/2023]
Abstract
Interactions between AMPA receptors and synaptic scaffolding proteins are key regulators of synaptic receptor density and, thereby, synapse strength. Shank3 is one such scaffolding protein with high clinical relevance, as genetic variants and deletions of this protein have been linked to autism spectrum disorder. Shank3 acts as a master regulator of the postsynaptic density of glutamatergic synapses, interacting with ionotropic and metabotropic glutamate receptors and cytoskeletal elements to modulate synaptic structure. Notably, Shank3 has been shown to interact directly with the AMPAR subunit GluA1, and Shank3 knockout animals show deficits in AMPAR-mediated synaptic transmission. In this study, we sought to characterize the stability of GluA1-Shank3 interaction in response to chronic stimuli using a highly sensitive and specific proximity ligation assay. We found that GluA1-Shank3 interactions decrease in response to prolonged neuronal depolarization induced by elevated extracellular potassium, and that this reduced interaction is blocked by NMDA receptor antagonism. These results firmly establish the close interaction of GluA1 and Shank3 in cortical neurons in vitro, and that this select interaction is subject to modulation by depolarization.
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Affiliation(s)
- Madeline M Ross
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Elias Aizenman
- Department of Neurobiology and Pittsburgh Institute for Neurodegenerative Disorders, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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11
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The role of post-translational modifications in synaptic AMPA receptor activity. Biochem Soc Trans 2023; 51:315-330. [PMID: 36629507 DOI: 10.1042/bst20220827] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 01/12/2023]
Abstract
AMPA-type receptors for the neurotransmitter glutamate are very dynamic entities, and changes in their synaptic abundance underlie different forms of synaptic plasticity, including long-term synaptic potentiation (LTP), long-term depression (LTD) and homeostatic scaling. The different AMPA receptor subunits (GluA1-GluA4) share a common modular structure and membrane topology, and their intracellular C-terminus tail is responsible for the interaction with intracellular proteins important in receptor trafficking. The latter sequence differs between subunits and contains most sites for post-translational modifications of the receptors, including phosphorylation, O-GlcNAcylation, ubiquitination, acetylation, palmitoylation and nitrosylation, which affect differentially the various subunits. Considering that each single subunit may undergo modifications in multiple sites, and that AMPA receptors may be formed by the assembly of different subunits, this creates multiple layers of regulation of the receptors with impact in synaptic function and plasticity. This review discusses the diversity of mechanisms involved in the post-translational modification of AMPA receptor subunits, and their impact on the subcellular distribution and synaptic activity of the receptors.
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12
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KASAI H. Unraveling the mysteries of dendritic spine dynamics: Five key principles shaping memory and cognition. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2023; 99:254-305. [PMID: 37821392 PMCID: PMC10749395 DOI: 10.2183/pjab.99.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 07/11/2023] [Indexed: 10/13/2023]
Abstract
Recent research extends our understanding of brain processes beyond just action potentials and chemical transmissions within neural circuits, emphasizing the mechanical forces generated by excitatory synapses on dendritic spines to modulate presynaptic function. From in vivo and in vitro studies, we outline five central principles of synaptic mechanics in brain function: P1: Stability - Underpinning the integral relationship between the structure and function of the spine synapses. P2: Extrinsic dynamics - Highlighting synapse-selective structural plasticity which plays a crucial role in Hebbian associative learning, distinct from pathway-selective long-term potentiation (LTP) and depression (LTD). P3: Neuromodulation - Analyzing the role of G-protein-coupled receptors, particularly dopamine receptors, in time-sensitive modulation of associative learning frameworks such as Pavlovian classical conditioning and Thorndike's reinforcement learning (RL). P4: Instability - Addressing the intrinsic dynamics crucial to memory management during continual learning, spotlighting their role in "spine dysgenesis" associated with mental disorders. P5: Mechanics - Exploring how synaptic mechanics influence both sides of synapses to establish structural traces of short- and long-term memory, thereby aiding the integration of mental functions. We also delve into the historical background and foresee impending challenges.
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Affiliation(s)
- Haruo KASAI
- International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
- Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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13
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Fawcett JW, Fyhn M, Jendelova P, Kwok JCF, Ruzicka J, Sorg BA. The extracellular matrix and perineuronal nets in memory. Mol Psychiatry 2022; 27:3192-3203. [PMID: 35760878 PMCID: PMC9708575 DOI: 10.1038/s41380-022-01634-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 05/09/2022] [Accepted: 05/16/2022] [Indexed: 02/06/2023]
Abstract
All components of the CNS are surrounded by a diffuse extracellular matrix (ECM) containing chondroitin sulphate proteoglycans (CSPGs), heparan sulphate proteoglycans (HSPGs), hyaluronan, various glycoproteins including tenascins and thrombospondin, and many other molecules that are secreted into the ECM and bind to ECM components. In addition, some neurons, particularly inhibitory GABAergic parvalbumin-positive (PV) interneurons, are surrounded by a more condensed cartilage-like ECM called perineuronal nets (PNNs). PNNs surround the soma and proximal dendrites as net-like structures that surround the synapses. Attention has focused on the role of PNNs in the control of plasticity, but it is now clear that PNNs also play an important part in the modulation of memory. In this review we summarize the role of the ECM, particularly the PNNs, in the control of various types of memory and their participation in memory pathology. PNNs are now being considered as a target for the treatment of impaired memory. There are many potential treatment targets in PNNs, mainly through modulation of the sulphation, binding, and production of the various CSPGs that they contain or through digestion of their sulphated glycosaminoglycans.
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Affiliation(s)
- James W Fawcett
- John van Geest Centre for Brain Repair, Department Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0PY, UK.
- Centre for Reconstructive Neuroscience, Institute for Experimental Medicine CAS, Videnska 1083, Prague 4, Prague, Czech Republic.
| | - Marianne Fyhn
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Pavla Jendelova
- Centre for Reconstructive Neuroscience, Institute for Experimental Medicine CAS, Videnska 1083, Prague 4, Prague, Czech Republic
| | - Jessica C F Kwok
- Centre for Reconstructive Neuroscience, Institute for Experimental Medicine CAS, Videnska 1083, Prague 4, Prague, Czech Republic
- School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Jiri Ruzicka
- Centre for Reconstructive Neuroscience, Institute for Experimental Medicine CAS, Videnska 1083, Prague 4, Prague, Czech Republic
| | - Barbara A Sorg
- Robert S. Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR, USA
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Editorial - The Making of Memories. Semin Cell Dev Biol 2022; 125:66-67. [PMID: 35135720 DOI: 10.1016/j.semcdb.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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