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Tymanskyj SR, Curran BM, Ma L. Selective axonal transport through branch junctions is directed by growth cone signaling and mediated by KIF1/kinesin-3 motors. Cell Rep 2022; 39:110748. [PMID: 35476993 PMCID: PMC9097860 DOI: 10.1016/j.celrep.2022.110748] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 01/27/2022] [Accepted: 04/06/2022] [Indexed: 11/16/2022] Open
Abstract
Development and function of nerve cells rely on the orchestration of microtubule-based transport from the cell body into distal axonal terminals. Neurons often have highly elaborate branches innervating multiple targets, but how protein or membrane cargos navigate through branch junctions to specific branch targets is unknown. Here, we demonstrate that anterograde transport of membrane vesicles through axonal branch junctions is highly selective, which is influenced by branch length and more strongly by growth cone motility. Using an optogenetic tool, we demonstrate that signaling from the growth cone can rapidly direct transport through branch junctions. We further demonstrate that such transport selectivity is differentially regulated for different vesicles and mediated by the KIF1/kinesin-3 family motors. We propose that this transport regulation through branch junctions could broadly impact neuronal development, function, and regeneration.
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Affiliation(s)
- Stephen R Tymanskyj
- Department of Neuroscience, Jefferson Center for Synaptic Biology, Vickie and Jack Farber Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Bridget M Curran
- Department of Neuroscience, Jefferson Center for Synaptic Biology, Vickie and Jack Farber Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Le Ma
- Department of Neuroscience, Jefferson Center for Synaptic Biology, Vickie and Jack Farber Institute for Neuroscience, Sydney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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52
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Lagardère M, Drouet A, Sainlos M, Thoumine O. High-Resolution Fluorescence Imaging Combined With Computer Simulations to Quantitate Surface Dynamics and Nanoscale Organization of Neuroligin-1 at Synapses. Front Synaptic Neurosci 2022; 14:835427. [PMID: 35546899 PMCID: PMC9083120 DOI: 10.3389/fnsyn.2022.835427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 03/09/2022] [Indexed: 11/13/2022] Open
Abstract
Neuroligins (NLGNs) form a family of cell adhesion molecules implicated in synapse development, but the mechanisms that retain these proteins at synapses are still incompletely understood. Recent studies indicate that surface-associated NLGN1 is diffusionally trapped at synapses, where it interacts with quasi-static scaffolding elements of the post-synaptic density. Whereas single molecule tracking reveals rapid diffusion and transient immobilization of NLGN1 at synapses within seconds, fluorescence recovery after photobleaching experiments indicate instead a long-term turnover of NLGN1 at synapse, in the hour time range. To gain insight into the mechanisms supporting NLGN1 anchorage at post-synapses and try to reconcile those experimental paradigms, we quantitatively analyzed here live-cell and super-resolution imaging experiments performed on NLGN1 using a newly released simulator of membrane protein dynamics for fluorescence microscopy, FluoSim. Based on a small set of parameters including diffusion coefficients, binding constants, and photophysical rates, the framework describes fairly well the dynamic behavior of extra-synaptic and synaptic NLGN1 over both short and long time ranges, and provides an estimate of NLGN1 copy numbers in post-synaptic densities at steady-state (around 50 dimers). One striking result is that the residence time of NLGN1 at synapses is much longer than what can be expected from extracellular interactions with pre-synaptic neurexins only, suggesting that NLGN1 is stabilized at synapses through multivalent interactions with intracellular post-synaptic scaffolding proteins.
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53
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Müller JA, Betzin J, Santos-Tejedor J, Mayer A, Oprişoreanu AM, Engholm-Keller K, Paulußen I, Gulakova P, McGovern TD, Gschossman LJ, Schönhense E, Wark JR, Lamprecht A, Becker AJ, Waardenberg AJ, Graham ME, Dietrich D, Schoch S. A presynaptic phosphosignaling hub for lasting homeostatic plasticity. Cell Rep 2022; 39:110696. [PMID: 35443170 DOI: 10.1016/j.celrep.2022.110696] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/26/2021] [Accepted: 03/29/2022] [Indexed: 11/29/2022] Open
Abstract
Stable function of networks requires that synapses adapt their strength to levels of neuronal activity, and failure to do so results in cognitive disorders. How such homeostatic regulation may be implemented in mammalian synapses remains poorly understood. Here we show that the phosphorylation status of several positions of the active-zone (AZ) protein RIM1 are relevant for synaptic glutamate release. Position RIMS1045 is necessary and sufficient for expression of silencing-induced homeostatic plasticity and is kept phosphorylated by serine arginine protein kinase 2 (SRPK2). SRPK2-induced upscaling of synaptic release leads to additional RIM1 nanoclusters and docked vesicles at the AZ and is not observed in the absence of RIM1 and occluded by RIMS1045E. Our data suggest that SRPK2 and RIM1 represent a presynaptic phosphosignaling hub that is involved in the homeostatic balance of synaptic coupling of neuronal networks.
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Affiliation(s)
- Johannes Alexander Müller
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany; Department of Neurosurgery, University Hospital Bonn, Bonn, Germany
| | - Julia Betzin
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany
| | - Jorge Santos-Tejedor
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany
| | - Annika Mayer
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany
| | - Ana-Maria Oprişoreanu
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany
| | - Kasper Engholm-Keller
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark; Synapse Proteomics, Children's Medical Research Institute, The University of Sydney, Westmead, NSW, Australia
| | | | - Polina Gulakova
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany; Department of Neurosurgery, University Hospital Bonn, Bonn, Germany
| | | | - Lena Johanna Gschossman
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany; Department of Neurosurgery, University Hospital Bonn, Bonn, Germany
| | - Eva Schönhense
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany
| | - Jesse R Wark
- Synapse Proteomics, Children's Medical Research Institute, The University of Sydney, Westmead, NSW, Australia
| | - Alf Lamprecht
- Department of Pharmaceutics, Bonn University, Bonn, Germany
| | - Albert J Becker
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany
| | - Ashley J Waardenberg
- Australian Institute for Tropical Health and Medicine, James Cook University, Smithfield, QLD 4878, Australia; i-Synapse, Cairns, QLD, Australia
| | - Mark E Graham
- Synapse Proteomics, Children's Medical Research Institute, The University of Sydney, Westmead, NSW, Australia
| | - Dirk Dietrich
- Department of Neurosurgery, University Hospital Bonn, Bonn, Germany.
| | - Susanne Schoch
- Section for Translational Epilepsy Research, Department of Neuropathology, University Hospital Bonn, Bonn, Germany.
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54
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Gookin SE, Taylor MR, Schwartz SL, Kennedy MJ, Dell’Acqua ML, Crosby KC, Smith KR. Complementary Use of Super-Resolution Imaging Modalities to Study the Nanoscale Architecture of Inhibitory Synapses. Front Synaptic Neurosci 2022; 14:852227. [PMID: 35463850 PMCID: PMC9024107 DOI: 10.3389/fnsyn.2022.852227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/08/2022] [Indexed: 11/13/2022] Open
Abstract
The nanoscale architecture of synapses has been investigated using multiple super-resolution methods, revealing a common modular structure for scaffolds, neurotransmitter receptors, and presynaptic proteins. This fundamental organization of proteins into subsynaptic domains (SSDs) is thought to be important for synaptic function and plasticity and common to many types of synapses. Using 3D super-resolution Structured Illumination Microscopy (3D-SIM), we recently showed that GABAergic inhibitory synapses exhibit this nanoscale organizational principle and are composed of SSDs of GABA A receptors (GABA A Rs), the inhibitory scaffold gephyrin, and the presynaptic active zone protein, RIM. Here, we have investigated the use of 3D-SIM and dSTORM to analyze the nanoscale architecture of the inhibitory synaptic adhesion molecule, neuroligin-2 (NL2). NL2 is a crucial mediator of inhibitory synapse formation and organization, associating with both GABA A Rs and gephyrin. However, the nanoscale sub-synaptic distribution NL2 remains unknown. We found that 3D-SIM and dSTORM provide complementary information regarding the distribution of NL2 at the inhibitory synapse, with NL2 forming nanoscale structures that have many similarities to gephyrin nanoscale architecture.
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Affiliation(s)
- Sara E. Gookin
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Matthew R. Taylor
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Samantha L. Schwartz
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Matthew J. Kennedy
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Mark L. Dell’Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Kevin C. Crosby
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, United States
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55
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Wegner W, Steffens H, Gregor C, Wolf F, Willig KI. Environmental enrichment enhances patterning and remodeling of synaptic nanoarchitecture as revealed by STED nanoscopy. eLife 2022; 11:73603. [PMID: 35195066 PMCID: PMC8903838 DOI: 10.7554/elife.73603] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 02/22/2022] [Indexed: 12/04/2022] Open
Abstract
Synaptic plasticity underlies long-lasting structural and functional changes to brain circuitry and its experience-dependent remodeling can be fundamentally enhanced by environmental enrichment. It is however unknown, whether and how the environmental enrichment alters the morphology and dynamics of individual synapses. Here, we present a virtually crosstalk-free two-color in vivo stimulated emission depletion (STED) microscope to simultaneously superresolve the dynamics of endogenous PSD95 of the post-synaptic density and spine geometry in the mouse cortex. In general, the spine head geometry and PSD95 assemblies were highly dynamic, their changes depended linearly on their original size but correlated only mildly. With environmental enrichment, the size distributions of PSD95 and spine head sizes were sharper than in controls, indicating that synaptic strength is set more uniformly. The topography of the PSD95 nanoorganization was more dynamic after environmental enrichment; changes in size were smaller but more correlated than in mice housed in standard cages. Thus, two-color in vivo time-lapse imaging of synaptic nanoorganization uncovers a unique synaptic nanoplasticity associated with the enhanced learning capabilities under environmental enrichment.
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Affiliation(s)
- Waja Wegner
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
| | - Heinz Steffens
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
| | - Carola Gregor
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Fred Wolf
- Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
| | - Katrin I Willig
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
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56
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Damstra HGJ, Mohar B, Eddison M, Akhmanova A, Kapitein LC, Tillberg PW. Visualizing cellular and tissue ultrastructure using Ten-fold Robust Expansion Microscopy (TREx). eLife 2022; 11:73775. [PMID: 35179128 PMCID: PMC8887890 DOI: 10.7554/elife.73775] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 01/30/2022] [Indexed: 12/18/2022] Open
Abstract
Expansion microscopy (ExM) is a powerful technique to overcome the diffraction limit of light microscopy that can be applied in both tissues and cells. In ExM, samples are embedded in a swellable polymer gel to physically expand the sample and isotropically increase resolution in x, y, and z. The maximum resolution increase is limited by the expansion factor of the gel, which is four-fold for the original ExM protocol. Variations on the original ExM method have been reported that allow for greater expansion factors but at the cost of ease of adoption or versatility. Here, we systematically explore the ExM recipe space and present a novel method termed Ten-fold Robust Expansion Microscopy (TREx) that, like the original ExM method, requires no specialized equipment or procedures. We demonstrate that TREx gels expand 10-fold, can be handled easily, and can be applied to both thick mouse brain tissue sections and cultured human cells enabling high-resolution subcellular imaging with a single expansion step. Furthermore, we show that TREx can provide ultrastructural context to subcellular protein localization by combining antibody-stained samples with off-the-shelf small-molecule stains for both total protein and membranes.
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Affiliation(s)
- Hugo G J Damstra
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Boaz Mohar
- Janelia Research Campus, HHMI, Ashburn, United States
| | - Mark Eddison
- Janelia Research Campus, HHMI, Ashburn, United States
| | - Anna Akhmanova
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Lukas C Kapitein
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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57
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Hruska M, Cain RE, Dalva MB. Nanoscale rules governing the organization of glutamate receptors in spine synapses are subunit specific. Nat Commun 2022; 13:920. [PMID: 35177616 PMCID: PMC8854560 DOI: 10.1038/s41467-022-28504-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 01/20/2022] [Indexed: 12/21/2022] Open
Abstract
Heterotetrameric glutamate receptors are essential for the development, function, and plasticity of spine synapses but how they are organized to achieve this is not known. Here we show that the nanoscale organization of glutamate receptors containing specific subunits define distinct subsynaptic features. Glutamate receptors containing GluA2 or GluN1 subunits establish nanomodular elements precisely positioned relative to Synaptotagmin-1 positive presynaptic release sites that scale with spine size. Glutamate receptors containing GluA1 or GluN2B specify features that exhibit flexibility: GluA1-subunit containing AMPARs are found in larger spines, while GluN2B-subunit containing NMDARs are enriched in the smallest spines with neither following a strict modular organization. Given that the precise positioning of distinct classes of glutamate receptors is linked to diverse events including cell death and synaptic plasticity, this unexpectedly robust synaptic nanoarchitecture provides a resilient system, where nanopositioned glutamate receptor heterotetramers define specific subsynaptic regions of individual spine synapses. Glutamate receptors comprise two obligate subunits and two subunits that confer distinct properties and functions to the specific tetramers, which also localize to distinct synaptic spines. Here, the authors use STimulated Emission Depletion nanoscopy (STED) to provide detailed insights into the spatial organization of glutamate receptor types.
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Affiliation(s)
- Martin Hruska
- Department of Neuroscience, Rockefeller Neuroscience Institute, West Virginia University, 108 Biomedical Road, Morgantown, WV, 26506, USA
| | - Rachel E Cain
- Department of Neuroscience and Jefferson Synaptic Biology Center, Sidney Kimmel Medical College at Thomas Jefferson University, 233 South 10th Street, Bluemle Life Sciences Building, Room 324, Philadelphia, PA, 19107, USA
| | - Matthew B Dalva
- Department of Neuroscience and Jefferson Synaptic Biology Center, Sidney Kimmel Medical College at Thomas Jefferson University, 233 South 10th Street, Bluemle Life Sciences Building, Room 324, Philadelphia, PA, 19107, USA.
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58
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Jackson RE, Compans B, Burrone J. Correlative Live-Cell and Super-Resolution Imaging to Link Presynaptic Molecular Organisation With Function. Front Synaptic Neurosci 2022; 14:830583. [PMID: 35242024 PMCID: PMC8885727 DOI: 10.3389/fnsyn.2022.830583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/12/2022] [Indexed: 11/13/2022] Open
Abstract
Information transfer at synapses occurs when vesicles fuse with the plasma membrane to release neurotransmitters, which then bind to receptors at the postsynaptic membrane. The process of neurotransmitter release varies dramatically between different synapses, but little is known about how this heterogeneity emerges. The development of super-resolution microscopy has revealed that synaptic proteins are precisely organised within and between the two parts of the synapse and that this precise spatiotemporal organisation fine-tunes neurotransmission. However, it remains unclear if variability in release probability could be attributed to the nanoscale organisation of one or several proteins of the release machinery. To begin to address this question, we have developed a pipeline for correlative functional and super-resolution microscopy, taking advantage of recent technological advancements enabling multicolour imaging. Here we demonstrate the combination of live imaging of SypHy-RGECO, a unique dual reporter that simultaneously measures presynaptic calcium influx and neurotransmitter release, with post hoc immunolabelling and multicolour single molecule localisation microscopy, to investigate the structure-function relationship at individual presynaptic boutons.
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Affiliation(s)
- Rachel E. Jackson
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Benjamin Compans
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
| | - Juan Burrone
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, United Kingdom
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59
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Takikawa K, Nishimune H. Similarity and Diversity of Presynaptic Molecules at Neuromuscular Junctions and Central Synapses. Biomolecules 2022; 12:biom12020179. [PMID: 35204679 PMCID: PMC8961632 DOI: 10.3390/biom12020179] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
Synaptic transmission is essential for controlling motor functions and maintaining brain functions such as walking, breathing, cognition, learning, and memory. Neurotransmitter release is regulated by presynaptic molecules assembled in active zones of presynaptic terminals. The size of presynaptic terminals varies, but the size of a single active zone and the types of presynaptic molecules are highly conserved among neuromuscular junctions (NMJs) and central synapses. Three parameters play an important role in the determination of neurotransmitter release properties at NMJs and central excitatory/inhibitory synapses: the number of presynaptic molecular clusters, the protein families of the presynaptic molecules, and the distance between presynaptic molecules and voltage-gated calcium channels. In addition, dysfunction of presynaptic molecules causes clinical symptoms such as motor and cognitive decline in patients with various neurological disorders and during aging. This review focuses on the molecular mechanisms responsible for the functional similarities and differences between excitatory and inhibitory synapses in the peripheral and central nervous systems, and summarizes recent findings regarding presynaptic molecules assembled in the active zone. Furthermore, we discuss the relationship between functional alterations of presynaptic molecules and dysfunction of NMJs or central synapses in diseases and during aging.
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Affiliation(s)
- Kenji Takikawa
- Laboratory of Neurobiology of Aging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan;
| | - Hiroshi Nishimune
- Laboratory of Neurobiology of Aging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi-ku, Tokyo 173-0015, Japan;
- Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-8-1 Harumi-cho, Fuchu-shi, Tokyo 183-8538, Japan
- Correspondence: ; Tel.: +81-3-3964-3241
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60
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Guzikowski NJ, Kavalali ET. Nano-Organization at the Synapse: Segregation of Distinct Forms of Neurotransmission. Front Synaptic Neurosci 2022; 13:796498. [PMID: 35002671 PMCID: PMC8727373 DOI: 10.3389/fnsyn.2021.796498] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 11/19/2021] [Indexed: 01/01/2023] Open
Abstract
Synapses maintain synchronous, asynchronous, and spontaneous modes of neurotransmission through distinct molecular and biochemical pathways. Traditionally a single synapse was assumed to have a homogeneous organization of molecular components both at the active zone and post-synaptically. However, recent advancements in experimental tools and the further elucidation of the physiological significance of distinct forms of release have challenged this notion. In comparison to rapid evoked release, the physiological significance of both spontaneous and asynchronous neurotransmission has only recently been considered in parallel with synaptic structural organization. Active zone nanostructure aligns with postsynaptic nanostructure creating a precise trans-synaptic alignment of release sites and receptors shaping synaptic efficacy, determining neurotransmission reliability, and tuning plasticity. This review will discuss how studies delineating synaptic nanostructure create a picture of a molecularly heterogeneous active zone tuned to distinct forms of release that may dictate diverse synaptic functional outputs.
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Affiliation(s)
- Natalie J Guzikowski
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, United States
| | - Ege T Kavalali
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States.,Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, United States
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61
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Wichmann C, Kuner T. Heterogeneity of glutamatergic synapses: cellular mechanisms and network consequences. Physiol Rev 2022; 102:269-318. [PMID: 34727002 DOI: 10.1152/physrev.00039.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chemical synapses are commonly known as a structurally and functionally highly diverse class of cell-cell contacts specialized to mediate communication between neurons. They represent the smallest "computational" unit of the brain and are typically divided into excitatory and inhibitory as well as modulatory categories. These categories are subdivided into diverse types, each representing a different structure-function repertoire that in turn are thought to endow neuronal networks with distinct computational properties. The diversity of structure and function found among a given category of synapses is referred to as heterogeneity. The main building blocks for this heterogeneity are synaptic vesicles, the active zone, the synaptic cleft, the postsynaptic density, and glial processes associated with the synapse. Each of these five structural modules entails a distinct repertoire of functions, and their combination specifies the range of functional heterogeneity at mammalian excitatory synapses, which are the focus of this review. We describe synapse heterogeneity that is manifested on different levels of complexity ranging from the cellular morphology of the pre- and postsynaptic cells toward the expression of different protein isoforms at individual release sites. We attempt to define the range of structural building blocks that are used to vary the basic functional repertoire of excitatory synaptic contacts and discuss sources and general mechanisms of synapse heterogeneity. Finally, we explore the possible impact of synapse heterogeneity on neuronal network function.
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Affiliation(s)
- Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Institute for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg, Germany
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62
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Kastian RF, Minegishi T, Inagaki N. Simultaneous analyses of clutch coupling and actin polymerization in dendritic spines of rodent hippocampal neurons during chemical LTP. STAR Protoc 2021; 2:100904. [PMID: 34723214 PMCID: PMC8536781 DOI: 10.1016/j.xpro.2021.100904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Dendritic spine enlargement by synaptic activation is thought to increase synaptic efficacy underlying learning and memory. This process requires forces generated by actin polymerization and actin-adhesion coupling (clutch coupling). Here, we describe a protocol to monitor actin filament retrograde flow and actin polymerization within spines using a standard epi-fluorescence microscope. In combination with chemical long-term potentiation, this protocol allows us to quantify clutch coupling efficiency and actin polymerization rate, which are essential variables for generating forces for activity-dependent spine enlargement. For complete details on the use and execution of this protocol, please refer to Kastian et al. (2021). Analysis of F-actin retrograde flow using a standard epi-fluorescence microscope F-actin flow velocity reflects the efficiency of clutch coupling Analysis of actin polymerization rate using a standard epi-fluorescence microscope Analysis of these variables in dendritic spines during chemical LTP induction
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Affiliation(s)
- Ria Fajarwati Kastian
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Takunori Minegishi
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Naoyuki Inagaki
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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63
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Aleksejenko N, Heller J. Super-resolution imaging to reveal the nanostructure of tripartite synapses. Neuronal Signal 2021; 5:NS20210003. [PMID: 34737894 PMCID: PMC8536832 DOI: 10.1042/ns20210003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/24/2021] [Accepted: 09/28/2021] [Indexed: 12/13/2022] Open
Abstract
Even though neurons are the main drivers of information processing in the brain and spinal cord, other cell types are important to mediate adequate flow of information. These include electrically passive glial cells such as microglia and astrocytes, which recently emerged as active partners facilitating proper signal transduction. In disease, these cells undergo pathophysiological changes that propel disease progression and change synaptic connections and signal transmission. In the healthy brain, astrocytic processes contact pre- and postsynaptic structures. These processes can be nanoscopic, and therefore only electron microscopy has been able to reveal their structure and morphology. However, electron microscopy is not suitable in revealing dynamic changes, and it is labour- and time-intensive. The dawn of super-resolution microscopy, techniques that 'break' the diffraction limit of conventional light microscopy, over the last decades has enabled researchers to reveal the nanoscopic synaptic environment. In this review, we highlight and discuss recent advances in our understanding of the nano-world of the so-called tripartite synapses, the relationship between pre- and postsynapse as well as astrocytic processes. Overall, novel super-resolution microscopy methods are needed to fully illuminate the intimate relationship between glia and neuronal cells that underlies signal transduction in the brain and that might be affected in diseases such as Alzheimer's disease and epilepsy.
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Affiliation(s)
- Natalija Aleksejenko
- School of Biotechnology and National Institute for Cellular Biotechnology (NICB), Dublin City University, Glasnevin, Ireland
| | - Janosch P. Heller
- School of Biotechnology and National Institute for Cellular Biotechnology (NICB), Dublin City University, Glasnevin, Ireland
- Queen Square Institute of Neurology, University College London, London, United Kingdom
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Nanoscale Sub-Compartmentalization of the Dendritic Spine Compartment. Biomolecules 2021; 11:biom11111697. [PMID: 34827695 PMCID: PMC8615865 DOI: 10.3390/biom11111697] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 01/04/2023] Open
Abstract
Compartmentalization of the membrane is essential for cells to perform highly specific tasks and spatially constrained biochemical functions in topographically defined areas. These membrane lateral heterogeneities range from nanoscopic dimensions, often involving only a few molecular constituents, to micron-sized mesoscopic domains resulting from the coalescence of nanodomains. Short-lived domains lasting for a few milliseconds coexist with more stable platforms lasting from minutes to days. This panoply of lateral domains subserves the great variety of demands of cell physiology, particularly high for those implicated in signaling. The dendritic spine, a subcellular structure of neurons at the receiving (postsynaptic) end of central nervous system excitatory synapses, exploits this compartmentalization principle. In its most frequent adult morphology, the mushroom-shaped spine harbors neurotransmitter receptors, enzymes, and scaffolding proteins tightly packed in a volume of a few femtoliters. In addition to constituting a mesoscopic lateral heterogeneity of the dendritic arborization, the dendritic spine postsynaptic membrane is further compartmentalized into spatially delimited nanodomains that execute separate functions in the synapse. This review discusses the functional relevance of compartmentalization and nanodomain organization in synaptic transmission and plasticity and exemplifies the importance of this parcelization in various neurotransmitter signaling systems operating at dendritic spines, using two fast ligand-gated ionotropic receptors, the nicotinic acetylcholine receptor and the glutamatergic receptor, and a second-messenger G-protein coupled receptor, the cannabinoid receptor, as paradigmatic examples.
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65
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Super-resolution microscopy: a closer look at synaptic dysfunction in Alzheimer disease. Nat Rev Neurosci 2021; 22:723-740. [PMID: 34725519 DOI: 10.1038/s41583-021-00531-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2021] [Indexed: 11/08/2022]
Abstract
The synapse has emerged as a critical neuronal structure in the degenerative process of Alzheimer disease (AD), in which the pathogenic signals of two key players - amyloid-β (Aβ) and tau - converge, thereby causing synaptic dysfunction and cognitive deficits. The synapse presents a dynamic, confined microenvironment in which to explore how key molecules travel, localize, interact and assume different levels of organizational complexity, thereby affecting neuronal function. However, owing to their small size and the diffraction-limited resolution of conventional light microscopic approaches, investigating synaptic structure and dynamics has been challenging. Super-resolution microscopy (SRM) techniques have overcome the resolution barrier and are revolutionizing our quantitative understanding of biological systems in unprecedented spatio-temporal detail. Here we review critical new insights provided by SRM into the molecular architecture and dynamic organization of the synapse and, in particular, the interactions between Aβ and tau in this compartment. We further highlight how SRM can transform our understanding of the molecular pathological mechanisms that underlie AD. The application of SRM for understanding the roles of synapses in AD pathology will provide a stepping stone towards a broader understanding of dysfunction in other subcellular compartments and at cellular and circuit levels in this disease.
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Abstract
Fluorescence imaging techniques play a pivotal role in our understanding of the nervous system. The emergence of various super-resolution microscopy methods and specialized fluorescent probes enables direct insight into neuronal structure and protein arrangements in cellular subcompartments with so far unmatched resolution. Super-resolving visualization techniques in neurons unveil a novel understanding of cytoskeletal composition, distribution, motility, and signaling of membrane proteins, subsynaptic structure and function, and neuron-glia interaction. Well-defined molecular targets in autoimmune and neurodegenerative disease models provide excellent starting points for in-depth investigation of disease pathophysiology using novel and innovative imaging methodology. Application of super-resolution microscopy in human brain samples and for testing clinical biomarkers is still in its infancy but opens new opportunities for translational research in neurology and neuroscience. In this review, we describe how super-resolving microscopy has improved our understanding of neuronal and brain function and dysfunction in the last two decades.
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Affiliation(s)
- Christian Werner
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Christian Geis
- Section Translational Neuroimmunology, Department of Neurology, Jena University Hospital, Am Klinikum 1, 07747 Jena, Germany
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67
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Díaz-Alonso J, Nicoll RA. AMPA receptor trafficking and LTP: Carboxy-termini, amino-termini and TARPs. Neuropharmacology 2021; 197:108710. [PMID: 34271016 PMCID: PMC9122021 DOI: 10.1016/j.neuropharm.2021.108710] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/28/2021] [Accepted: 07/08/2021] [Indexed: 12/11/2022]
Abstract
AMPA receptors (AMPARs) are fundamental elements in excitatory synaptic transmission and synaptic plasticity in the CNS. Long term potentiation (LTP), a form of synaptic plasticity which contributes to learning and memory formation, relies on the accumulation of AMPARs at the postsynapse. This phenomenon requires the coordinated recruitment of different elements in the AMPAR complex. Based on recent research reviewed herein, we propose an updated AMPAR trafficking and LTP model which incorporates both extracellular as well as intracellular mechanisms. This article is part of the special Issue on 'Glutamate Receptors - AMPA receptors'.
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Affiliation(s)
- Javier Díaz-Alonso
- Department of Anatomy and Neurobiology, USA; Center for the Neurobiology of Learning and Memory, University of California at Irvine, USA.
| | - Roger A Nicoll
- Departments of Cellular and Molecular Pharmacology, USA; Physiology, University of California at San Francisco, USA.
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68
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Jing Y, Zhang C, Yu B, Lin D, Qu J. Super-Resolution Microscopy: Shedding New Light on In Vivo Imaging. Front Chem 2021; 9:746900. [PMID: 34595156 PMCID: PMC8476955 DOI: 10.3389/fchem.2021.746900] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 08/26/2021] [Indexed: 12/28/2022] Open
Abstract
Over the past two decades, super-resolution microscopy (SRM), which offered a significant improvement in resolution over conventional light microscopy, has become a powerful tool to visualize biological activities in both fixed and living cells. However, completely understanding biological processes requires studying cells in a physiological context at high spatiotemporal resolution. Recently, SRM has showcased its ability to observe the detailed structures and dynamics in living species. Here we summarized recent technical advancements in SRM that have been successfully applied to in vivo imaging. Then, improvements in the labeling strategies are discussed together with the spectroscopic and chemical demands of the fluorophores. Finally, we broadly reviewed the current applications for super-resolution techniques in living species and highlighted some inherent challenges faced in this emerging field. We hope that this review could serve as an ideal reference for researchers as well as beginners in the relevant field of in vivo super resolution imaging.
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Affiliation(s)
| | | | | | - Danying Lin
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Junle Qu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
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69
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Watson JF, Pinggera A, Ho H, Greger IH. AMPA receptor anchoring at CA1 synapses is determined by N-terminal domain and TARP γ8 interactions. Nat Commun 2021; 12:5083. [PMID: 34426577 PMCID: PMC8382838 DOI: 10.1038/s41467-021-25281-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/02/2021] [Indexed: 12/30/2022] Open
Abstract
AMPA receptor (AMPAR) abundance and positioning at excitatory synapses regulates the strength of transmission. Changes in AMPAR localisation can enact synaptic plasticity, allowing long-term information storage, and is therefore tightly controlled. Multiple mechanisms regulating AMPAR synaptic anchoring have been described, but with limited coherence or comparison between reports, our understanding of this process is unclear. Here, combining synaptic recordings from mouse hippocampal slices and super-resolution imaging in dissociated cultures, we compare the contributions of three AMPAR interaction domains controlling transmission at hippocampal CA1 synapses. We show that the AMPAR C-termini play only a modulatory role, whereas the extracellular N-terminal domain (NTD) and PDZ interactions of the auxiliary subunit TARP γ8 are both crucial, and each is sufficient to maintain transmission. Our data support a model in which γ8 accumulates AMPARs at the postsynaptic density, where the NTD further tunes their positioning. This interplay between cytosolic (TARP γ8) and synaptic cleft (NTD) interactions provides versatility to regulate synaptic transmission and plasticity.
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Affiliation(s)
- Jake F Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
- IST Austria, Am Campus 1, Klosterneuburg, Austria
| | - Alexandra Pinggera
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
| | - Hinze Ho
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom.
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70
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Sun Y, Smirnov M, Kamasawa N, Yasuda R. Rapid Ultrastructural Changes in the PSD and Surrounding Membrane after Induction of Structural LTP in Single Dendritic Spines. J Neurosci 2021; 41:7003-7014. [PMID: 34266899 PMCID: PMC8372018 DOI: 10.1523/jneurosci.1964-20.2021] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 06/05/2021] [Accepted: 06/10/2021] [Indexed: 11/21/2022] Open
Abstract
The structural plasticity of dendritic spines is considered to be an important basis of synaptic plasticity, learning, and memory. Here, we induced input-specific structural LTP (sLTP) in single dendritic spines in organotypic hippocampal slices from mice of either sex and performed ultrastructural analyses of the spines using efficient correlative light and electron microscopy. We observed reorganization of the PSD nanostructure, such as perforation and segmentation, at 2-3, 20, and 120 min after sLTP induction. In addition, PSD and nonsynaptic axon-spine interface (nsASI) membrane expanded unevenly during sLTP. Specifically, the PSD area showed a transient increase at 2-3 min after sLTP induction. The PSD growth was to a degree less than spine volume growth at 2-3 min and 20 min after sLTP induction but became similar at 120 min. On the other hand, the nsASI area showed a profound and lasting expansion, to a degree similar to spine volume growth throughout the process. These rapid ultrastructural changes in PSD and surrounding membrane may contribute to rapid electrophysiological plasticity during sLTP.SIGNIFICANCE STATEMENT To understand the ultrastructural changes during synaptic plasticity, it is desired to efficiently image single dendritic spines that underwent structural plasticity in electron microscopy. We induced structural long-term potentiation (sLTP) in single dendritic spines by two-photon glutamate uncaging. We then identified the same spines at different phases of sLTP and performed ultrastructural analysis by using an efficient correlative light and electron microscopy method. We found that postsynaptic density undergoes dramatic modification in its structural complexity immediately after sLTP induction. Meanwhile, the nonsynaptic axon-spine interface area shows a rapid and sustained increase throughout sLTP. Our results indicate that the uneven modification of synaptic and nonsynaptic postsynaptic membrane might contribute to rapid electrophysiological plasticity during sLTP.
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Affiliation(s)
- Ye Sun
- Neuronal Signal Transduction Group, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
- Integrative Biology and Neuroscience Graduate Program, Florida Atlantic University, Jupiter, Florida 33458
- International Max Planck Research School for Brain and Behavior, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Michael Smirnov
- Neuronal Signal Transduction Group, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
- International Max Planck Research School for Brain and Behavior, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
| | - Ryohei Yasuda
- Neuronal Signal Transduction Group, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
- Integrative Biology and Neuroscience Graduate Program, Florida Atlantic University, Jupiter, Florida 33458
- International Max Planck Research School for Brain and Behavior, Max Planck Florida Institute for Neuroscience, Jupiter, Florida 33458
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71
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Hayashi Y. Molecular mechanism of hippocampal long-term potentiation - Towards multiscale understanding of learning and memory. Neurosci Res 2021; 175:3-15. [PMID: 34375719 DOI: 10.1016/j.neures.2021.08.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 11/16/2022]
Abstract
Long-term potentiation (LTP) of synaptic transmission is considered to be a cellular counterpart of learning and memory. Activation of postsynaptic NMDA type glutamate receptor (NMDA-R) induces trafficking of AMPA type glutamate receptors (AMPA-R) and other proteins to the synapse in sequential fashion. At the same time, the dendritic spine expands for long-term and modulation of actin underlies this (structural LTP or sLTP). How these changes persist despite constant diffusion and turnover of the component proteins have been the central focus of the current LTP research. Signaling triggered by Ca2+-influx via NMDA-R triggers kinase including Ca2+/calmodulin-dependent protein kinase II (CaMKII). CaMKII can sustain longer-term biochemical signaling by forming a reciprocally-activating kinase-effector complex with its substrate proteins including Tiam1, thereby regulating persistence of the downstream signaling. Furthermore, activated CaMKII can condense at the synapse through the mechanism of liquid-liquid phase separation (LLPS). This increases the binding capacity at the synapse, thereby contributing to the maintenance of enlarged protein complexes. It may also serve as the synapse tag, which captures newly synthesized proteins.
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Affiliation(s)
- Yasunori Hayashi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan.
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72
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A large-scale nanoscopy and biochemistry analysis of postsynaptic dendritic spines. Nat Neurosci 2021; 24:1151-1162. [PMID: 34168338 DOI: 10.1038/s41593-021-00874-w] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 05/13/2021] [Indexed: 02/05/2023]
Abstract
Dendritic spines, the postsynaptic compartments of excitatory neurotransmission, have different shapes classified from 'stubby' to 'mushroom-like'. Whereas mushroom spines are essential for adult brain function, stubby spines disappear during brain maturation. It is still unclear whether and how they differ in protein composition. To address this, we combined electron microscopy and quantitative biochemistry with super-resolution microscopy to annotate more than 47,000 spines for more than 100 synaptic targets. Surprisingly, mushroom and stubby spines have similar average protein copy numbers and topologies. However, an analysis of the correlation of each protein to the postsynaptic density mass, used as a marker of synaptic strength, showed substantially more significant results for the mushroom spines. Secretion and trafficking proteins correlated particularly poorly to the strength of stubby spines. This suggests that stubby spines are less likely to adequately respond to dynamic changes in synaptic transmission than mushroom spines, which possibly explains their loss during brain maturation.
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73
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Ramsey AM, Tang AH, LeGates TA, Gou XZ, Carbone BE, Thompson SM, Biederer T, Blanpied TA. Subsynaptic positioning of AMPARs by LRRTM2 controls synaptic strength. SCIENCE ADVANCES 2021; 7:7/34/eabf3126. [PMID: 34417170 PMCID: PMC8378824 DOI: 10.1126/sciadv.abf3126] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 06/30/2021] [Indexed: 05/07/2023]
Abstract
Recent evidence suggests that nano-organization of proteins within synapses may control the strength of communication between neurons in the brain. The unique subsynaptic distribution of glutamate receptors, which cluster in nanoalignment with presynaptic sites of glutamate release, supports this hypothesis. However, testing it has been difficult because mechanisms controlling subsynaptic organization remain unknown. Reasoning that transcellular interactions could position AMPA receptors (AMPARs), we targeted a key transsynaptic adhesion molecule implicated in controlling AMPAR number, LRRTM2, using engineered, rapid proteolysis. Severing the LRRTM2 extracellular domain led quickly to nanoscale declustering of AMPARs away from release sites, not prompting their escape from synapses until much later. This rapid remodeling of AMPAR position produced significant deficits in evoked, but not spontaneous, postsynaptic receptor activation. These results dissociate receptor numbers from their nanopositioning in determination of synaptic function and support the novel concept that adhesion molecules acutely position receptors to dynamically control synaptic strength.
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Affiliation(s)
- Austin M Ramsey
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ai-Hui Tang
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Tara A LeGates
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | | - Beatrice E Carbone
- Department of Neurology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Scott M Thompson
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Thomas Biederer
- Department of Neurology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Thomas A Blanpied
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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74
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Zieger HL, Choquet D. Nanoscale synapse organization and dysfunction in neurodevelopmental disorders. Neurobiol Dis 2021; 158:105453. [PMID: 34314857 DOI: 10.1016/j.nbd.2021.105453] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 07/18/2021] [Accepted: 07/21/2021] [Indexed: 12/20/2022] Open
Abstract
Neurodevelopmental disorders such as those linked to intellectual disabilities or autism spectrum disorder are thought to originate in part from genetic defects in synaptic proteins. Single gene mutations linked to synapse dysfunction can broadly be separated in three categories: disorders of transcriptional regulation, disorders of synaptic signaling and disorders of synaptic scaffolding and structures. The recent developments in super-resolution imaging technologies and their application to synapses have unraveled a complex nanoscale organization of synaptic components. On the one hand, part of receptors, adhesion proteins, ion channels, scaffold elements and the pre-synaptic release machinery are partitioned in subsynaptic nanodomains, and the respective organization of these nanodomains has tremendous impact on synaptic function. For example, pre-synaptic neurotransmitter release sites are partly aligned with nanometer precision to postsynaptic receptor clusters. On the other hand, a large fraction of synaptic components is extremely dynamic and constantly exchanges between synaptic domains and extrasynaptic or intracellular compartments. It is largely the combination of the exquisitely precise nanoscale synaptic organization of synaptic components and their high dynamic that allows the rapid and profound regulation of synaptic function during synaptic plasticity processes that underlie adaptability of brain function, learning and memory. It is very tempting to speculate that genetic defects that lead to neurodevelopmental disorders and target synaptic scaffolds and structures mediate their deleterious impact on brain function through perturbing synapse nanoscale dynamic organization. We discuss here how applying super-resolution imaging methods in models of neurodevelopmental disorders could help in addressing this question.
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Affiliation(s)
- Hanna L Zieger
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000 Bordeaux, France
| | - Daniel Choquet
- Univ. Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, F-33000 Bordeaux, France; Univ. Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, F-33000 Bordeaux, France.
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75
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Lu H, Fang L, Wang J, Zhao F, Liu C, Gao Y, Liu J, Min W. Pine nut antioxidant peptides ameliorate the memory impairment in a scopolamine-induced mouse model via SIRT3-induced synaptic plasticity. Food Funct 2021; 12:8026-8036. [PMID: 34269783 DOI: 10.1039/d1fo01817e] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This study aimed to investigate the effects of a pine nut albumin hydrolysate (fraction <3 kDa) and of its short peptide derivative, Trp-Tyr-Pro-Gly-Lys (WYPGK), on synaptic plasticity and memory function in scopolamine-induced memory-impaired mice, as well as the potential underlying mechanism in PC12 cells. In the scopolamine-induced mouse model, the results revealed that the fraction <3 kDa and WYPGK enhanced synaptic plasticity and improved learning and memory function. H&E and Nissl staining analysis showed that the damage in hippocampal neurons was decreased. Golgi staining and transmission electron microscopy further revealed that the enhanced synaptic plasticity was associated with increased dendritic spine abundance and synaptic density. In an H2O2-induced PC12 cell model, treatment with mitochondrial sirtuin 3 (SIRT3) inhibitor and inducer molecules confirmed that the <3 kDa fraction and WYPGK activated SIRT3, leading to the decrease in Ace-SOD2 acetylation and increasing the expression of SYP, SYN-1, SNAP25, and PSD95, thus enhancing synaptic plasticity. The <3 kDa fraction and WYPGK also activated the ERK/CREB pathway and upregulated the expression of brain-derived neurotrophic factor. Our results show that fraction <3 kDa and WYPGK improve learning and memory ability through SIRT3-induced synaptic plasticity in vitro and in vivo.
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Affiliation(s)
- Hongyan Lu
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, P. R. China.
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76
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Abstract
This study presents evidence that the MAGUK family of synaptic scaffolding proteins plays an essential, but redundant, role in long-term potentiation (LTP). The action of PSD-95, but not that of SAP102, requires the binding to the transsynaptic adhesion protein ADAM22, which is required for nanocolumn stabilization. Based on these and previous results, we propose a two-step process in the recruitment of AMPARs during LTP. First, AMPARs, via TARPs, bind to exposed PSD-95 in the PSD. This alone is not adequate to enhance synaptic transmission. Second, the AMPAR/TARP/PSD-95 complex is stabilized in the nanocolumn by binding to ADAM22. A second, ADAM22-independent pathway is proposed for SAP102.
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77
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Orlando M, Dvorzhak A, Bruentgens F, Maglione M, Rost BR, Sigrist SJ, Breustedt J, Schmitz D. Recruitment of release sites underlies chemical presynaptic potentiation at hippocampal mossy fiber boutons. PLoS Biol 2021; 19:e3001149. [PMID: 34153028 PMCID: PMC8216508 DOI: 10.1371/journal.pbio.3001149] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 02/17/2021] [Indexed: 01/14/2023] Open
Abstract
Synaptic plasticity is a cellular model for learning and memory. However, the expression mechanisms underlying presynaptic forms of plasticity are not well understood. Here, we investigate functional and structural correlates of presynaptic potentiation at large hippocampal mossy fiber boutons induced by the adenylyl cyclase activator forskolin. We performed 2-photon imaging of the genetically encoded glutamate sensor iGluu that revealed an increase in the surface area used for glutamate release at potentiated terminals. Time-gated stimulated emission depletion microscopy revealed no change in the coupling distance between P/Q-type calcium channels and release sites mapped by Munc13-1 cluster position. Finally, by high-pressure freezing and transmission electron microscopy analysis, we found a fast remodeling of synaptic ultrastructure at potentiated boutons: Synaptic vesicles dispersed in the terminal and accumulated at the active zones, while active zone density and synaptic complexity increased. We suggest that these rapid and early structural rearrangements might enable long-term increase in synaptic strength.
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Affiliation(s)
- Marta Orlando
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Berlin, Germany
| | - Anton Dvorzhak
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Berlin, Germany
| | - Felicitas Bruentgens
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Berlin, Germany
| | - Marta Maglione
- NeuroCure Cluster of Excellence, Berlin, Germany
- Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Benjamin R. Rost
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Stephan J. Sigrist
- NeuroCure Cluster of Excellence, Berlin, Germany
- Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, Berlin, Germany
- German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Jörg Breustedt
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Berlin, Germany
| | - Dietmar Schmitz
- Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
- NeuroCure Cluster of Excellence, Berlin, Germany
- German Center for Neurodegenerative Diseases, Berlin, Germany
- Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany
- Einstein Center for Neurosciences Berlin, Berlin, Germany
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
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78
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Steffens H, Mott AC, Li S, Wegner W, Švehla P, Kan VWY, Wolf F, Liebscher S, Willig KI. Stable but not rigid: Chronic in vivo STED nanoscopy reveals extensive remodeling of spines, indicating multiple drivers of plasticity. SCIENCE ADVANCES 2021; 7:7/24/eabf2806. [PMID: 34108204 PMCID: PMC8189587 DOI: 10.1126/sciadv.abf2806] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/22/2021] [Indexed: 06/01/2023]
Abstract
Excitatory synapses on dendritic spines of pyramidal neurons are considered a central memory locus. To foster both continuous adaption and the storage of long-term information, spines need to be plastic and stable at the same time. Here, we advanced in vivo STED nanoscopy to superresolve distinct features of spines (head size and neck length/width) in mouse neocortex for up to 1 month. While LTP-dependent changes predict highly correlated modifications of spine geometry, we find both, uncorrelated and correlated dynamics, indicating multiple independent drivers of spine remodeling. The magnitude of this remodeling suggests substantial fluctuations in synaptic strength. Despite this high degree of volatility, all spine features exhibit persistent components that are maintained over long periods of time. Furthermore, chronic nanoscopy uncovers structural alterations in the cortex of a mouse model of neurodegeneration. Thus, at the nanoscale, stable dendritic spines exhibit a delicate balance of stability and volatility.
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Affiliation(s)
- Heinz Steffens
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Alexander C Mott
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Siyuan Li
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Waja Wegner
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Pavel Švehla
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Vanessa W Y Kan
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Fred Wolf
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization; Campus Institute for Dynamics of Biological Networks, Göttingen, Germany
| | - Sabine Liebscher
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany.
- BioMedical Center, Faculty of Medicine, Ludwig-Maximilians-University Munich, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Katrin I Willig
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany.
- Max Planck Institute of Experimental Medicine, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
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79
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Feng Z, Wu X, Zhang M. Presynaptic bouton compartmentalization and postsynaptic density-mediated glutamate receptor clustering via phase separation. Neuropharmacology 2021; 193:108622. [PMID: 34051266 DOI: 10.1016/j.neuropharm.2021.108622] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/25/2021] [Accepted: 05/17/2021] [Indexed: 01/21/2023]
Abstract
Neuronal synapses encompass three compartments: presynaptic axon terminal, synaptic cleft, and postsynaptic dendrite. Each compartment contains densely packed molecular machineries that are involved in synaptic transmission. In recent years, emerging evidence indicates that the assembly of these membraneless substructures or assemblies that are not enclosed by membranes are driven by liquid-liquid phase separation. We review here recent studies that suggest the phase separation-mediated organization of these synaptic compartments. We discuss how synaptic function may be linked to its organization as biomolecular condensates. We conclude with a discussion of areas of future interest in the field for better understanding of the structural architecture of neuronal synapses and its contribution to synaptic functions.
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Affiliation(s)
- Zhe Feng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xiandeng Wu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Mingjie Zhang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
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80
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LGI1-ADAM22-MAGUK configures transsynaptic nanoalignment for synaptic transmission and epilepsy prevention. Proc Natl Acad Sci U S A 2021; 118:2022580118. [PMID: 33397806 PMCID: PMC7826393 DOI: 10.1073/pnas.2022580118] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
This study addresses a fundamental question in neuroscience, namely how does the presynaptic component of the synapse precisely align with the postsynaptic component? This is essential for the proper transmission of signals across the synapse. This paper focuses on a set of transsynaptic, epilepsy-related proteins that are essential for this alignment. We show that the LGI1–ADAM22–MAGUK complex is a key player in the nanoarchitecture of the synapse, such that the release site is directly apposed to the nanocluster of glutamate receptors. Physiological functioning and homeostasis of the brain rely on finely tuned synaptic transmission, which involves nanoscale alignment between presynaptic neurotransmitter-release machinery and postsynaptic receptors. However, the molecular identity and physiological significance of transsynaptic nanoalignment remain incompletely understood. Here, we report that epilepsy gene products, a secreted protein LGI1 and its receptor ADAM22, govern transsynaptic nanoalignment to prevent epilepsy. We found that LGI1–ADAM22 instructs PSD-95 family membrane-associated guanylate kinases (MAGUKs) to organize transsynaptic protein networks, including NMDA/AMPA receptors, Kv1 channels, and LRRTM4–Neurexin adhesion molecules. Adam22ΔC5/ΔC5 knock-in mice devoid of the ADAM22–MAGUK interaction display lethal epilepsy of hippocampal origin, representing the mouse model for ADAM22-related epileptic encephalopathy. This model shows less-condensed PSD-95 nanodomains, disordered transsynaptic nanoalignment, and decreased excitatory synaptic transmission in the hippocampus. Strikingly, without ADAM22 binding, PSD-95 cannot potentiate AMPA receptor-mediated synaptic transmission. Furthermore, forced coexpression of ADAM22 and PSD-95 reconstitutes nano-condensates in nonneuronal cells. Collectively, this study reveals LGI1–ADAM22–MAGUK as an essential component of transsynaptic nanoarchitecture for precise synaptic transmission and epilepsy prevention.
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81
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Kastian RF, Minegishi T, Baba K, Saneyoshi T, Katsuno-Kambe H, Saranpal S, Hayashi Y, Inagaki N. Shootin1a-mediated actin-adhesion coupling generates force to trigger structural plasticity of dendritic spines. Cell Rep 2021; 35:109130. [PMID: 34010643 DOI: 10.1016/j.celrep.2021.109130] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 03/09/2021] [Accepted: 04/22/2021] [Indexed: 12/19/2022] Open
Abstract
Dendritic spines constitute the major compartments of excitatory post-synapses. They undergo activity-dependent enlargement, which is thought to increase the synaptic efficacy underlying learning and memory. The activity-dependent spine enlargement requires activation of signaling pathways leading to promotion of actin polymerization within the spines. However, the molecular machinery that suffices for that structural plasticity remains unclear. Here, we demonstrate that shootin1a links polymerizing actin filaments in spines with the cell-adhesion molecules N-cadherin and L1-CAM, thereby mechanically coupling the filaments to the extracellular environment. Synaptic activation enhances shootin1a-mediated actin-adhesion coupling in spines. Promotion of actin polymerization is insufficient for the plasticity; the enhanced actin-adhesion coupling is required for polymerizing actin filaments to push against the membrane for spine enlargement. By integrating cell signaling, cell adhesion, and force generation into the current model of actin-based machinery, we propose molecular machinery that is sufficient to trigger the activity-dependent spine structural plasticity.
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Affiliation(s)
- Ria Fajarwati Kastian
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Takunori Minegishi
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kentarou Baba
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Takeo Saneyoshi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Hiroko Katsuno-Kambe
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Singh Saranpal
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Yasunori Hayashi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Naoyuki Inagaki
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.
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82
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CaMKII activation persistently segregates postsynaptic proteins via liquid phase separation. Nat Neurosci 2021; 24:777-785. [PMID: 33927400 DOI: 10.1038/s41593-021-00843-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 03/22/2021] [Indexed: 11/08/2022]
Abstract
Transient information input to the brain leads to persistent changes in synaptic circuits, contributing to the formation of memory engrams. Pre- and postsynaptic structures undergo coordinated functional and structural changes during this process, but how such changes are achieved by their component molecules remains largely unknown. We found that activated CaMKII, a central player of synaptic plasticity, undergoes liquid-liquid phase separation with the NMDA-type glutamate receptor subunit GluN2B. Due to CaMKII autophosphorylation, the condensate stably persists even after Ca2+ is removed. The selective binding of activated CaMKII with GluN2B cosegregates AMPA receptors and the synaptic adhesion molecule neuroligin into a phase-in-phase assembly. In this way, Ca2+-induced liquid-liquid phase separation of CaMKII has the potential to act as an activity-dependent mechanism to crosslink postsynaptic proteins, which may serve as a platform for synaptic reorganization associated with synaptic plasticity.
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83
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Choquet D, Sainlos M, Sibarita JB. Advanced imaging and labelling methods to decipher brain cell organization and function. Nat Rev Neurosci 2021; 22:237-255. [PMID: 33712727 DOI: 10.1038/s41583-021-00441-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2021] [Indexed: 01/31/2023]
Abstract
The brain is arguably the most complex organ. The branched and extended morphology of nerve cells, their subcellular complexity, the multiplicity of brain cell types as well as their intricate connectivity and the scattering properties of brain tissue present formidable challenges to the understanding of brain function. Neuroscientists have often been at the forefront of technological and methodological developments to overcome these hurdles to visualize, quantify and modify cell and network properties. Over the last few decades, the development of advanced imaging methods has revolutionized our approach to explore the brain. Super-resolution microscopy and tissue imaging approaches have recently exploded. These instrumentation-based innovations have occurred in parallel with the development of new molecular approaches to label protein targets, to evolve new biosensors and to target them to appropriate cell types or subcellular compartments. We review the latest developments for labelling and functionalizing proteins with small localization and functionalized reporters. We present how these molecular tools are combined with the development of a wide variety of imaging methods that break either the diffraction barrier or the tissue penetration depth limits. We put these developments in perspective to emphasize how they will enable step changes in our understanding of the brain.
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Affiliation(s)
- Daniel Choquet
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France. .,University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4, Bordeaux, France.
| | - Matthieu Sainlos
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
| | - Jean-Baptiste Sibarita
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France.
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84
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Yang X, Annaert W. The Nanoscopic Organization of Synapse Structures: A Common Basis for Cell Communication. MEMBRANES 2021; 11:248. [PMID: 33808285 PMCID: PMC8065904 DOI: 10.3390/membranes11040248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 03/26/2021] [Accepted: 03/27/2021] [Indexed: 11/16/2022]
Abstract
Synapse structures, including neuronal and immunological synapses, can be seen as the plasma membrane contact sites between two individual cells where information is transmitted from one cell to the other. The distance between the two plasma membranes is only a few tens of nanometers, but these areas are densely populated with functionally different proteins, including adhesion proteins, receptors, and transporters. The narrow space between the two plasma membranes has been a barrier for resolving the synaptic architecture due to the diffraction limit in conventional microscopy (~250 nm). Various advanced super-resolution microscopy techniques, such as stimulated emission depletion (STED), structured illumination microscopy (SIM), and single-molecule localization microscopy (SMLM), bypass the diffraction limit and provide a sub-diffraction-limit resolving power, ranging from 10 to 100 nm. The studies using super-resolution microscopy have revealed unprecedented details of the nanoscopic organization and dynamics of synaptic molecules. In general, most synaptic proteins appear to be heterogeneously distributed and form nanodomains at the membranes. These nanodomains are dynamic functional units, playing important roles in mediating signal transmission through synapses. Herein, we discuss our current knowledge on the super-resolution nanoscopic architecture of synapses and their functional implications, with a particular focus on the neuronal synapses and immune synapses.
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Affiliation(s)
| | - Wim Annaert
- VIB Center for Brain and Disease Research and KU Leuven, Department of Neurosciences, Gasthuisberg, B-3000 Leuven, Belgium;
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85
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Becker MFP, Tetzlaff C. The biophysical basis underlying the maintenance of early phase long-term potentiation. PLoS Comput Biol 2021; 17:e1008813. [PMID: 33750943 PMCID: PMC8016278 DOI: 10.1371/journal.pcbi.1008813] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 04/01/2021] [Accepted: 02/17/2021] [Indexed: 11/18/2022] Open
Abstract
The maintenance of synaptic changes resulting from long-term potentiation (LTP) is essential for brain function such as memory and learning. Different LTP phases have been associated with diverse molecular processes and pathways, and the molecular underpinnings of LTP on the short, as well as long time scales, are well established. However, the principles on the intermediate time scale of 1-6 hours that mediate the early phase of LTP (E-LTP) remain elusive. We hypothesize that the interplay between specific features of postsynaptic receptor trafficking is responsible for sustaining synaptic changes during this LTP phase. We test this hypothesis by formalizing a biophysical model that integrates several experimentally-motivated mechanisms. The model captures a wide range of experimental findings and predicts that synaptic changes are preserved for hours when the receptor dynamics are shaped by the interplay of structural changes of the spine in conjunction with increased trafficking from recycling endosomes and the cooperative binding of receptors. Furthermore, our model provides several predictions to verify our findings experimentally. The cognitive ability of learning is associated with plasticity-induced changes in synaptic transmission efficacy mediated by AMPA receptors. Synaptic changes depend on a multitude of molecular and physiological mechanisms, building complex interaction networks. By formalizing and employing a biophysical model of AMPAR trafficking, we unravel and evaluate the interplay between key mechanisms such as receptor binding, exocytosis, morphological changes, and cooperative receptor binding. Our findings indicate that cooperative receptor binding in conjunction with morphological changes of the spine and increased trafficking from recycling endosomes leads to the maintenance of synaptic changes on behaviorally relevant time spans.
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Affiliation(s)
- Moritz F. P. Becker
- III. Institute of Physics – Biophysics, Georg-August University, Göttingen, Germany
- * E-mail: (MB); (CT)
| | - Christian Tetzlaff
- III. Institute of Physics – Biophysics, Georg-August University, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, Göttingen, Germany
- * E-mail: (MB); (CT)
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86
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Regulation of synaptic nanodomain by liquid-liquid phase separation: A novel mechanism of synaptic plasticity. Curr Opin Neurobiol 2021; 69:84-92. [PMID: 33752045 DOI: 10.1016/j.conb.2021.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/07/2021] [Accepted: 02/08/2021] [Indexed: 12/22/2022]
Abstract
Advances in microscopy techniques have revealed the details of synaptic nanodomains as defined by the segregation of specific molecules on or beneath both presynaptic and postsynaptic membranes. However, it is yet to be clarified how such segregation is accomplished without demarcating membrane and how nanodomains respond to the neuronal activity. It was recently discovered that proteins at the synapse undergo liquid-liquid phase separation (LLPS), which not only contributes to the accumulation of synaptic proteins but also to further segregating the proteins into subdomains by forming phase-in-phase structures. More specifically, CaMKII, a postsynaptic multifunctional kinase that serves as a signaling molecule, acts as a synaptic cross-linker which segregates certain molecules through LLPS in a manner triggered by Ca2+. Nanodomain formation contributes to the establishment of trans-synaptic nanocolumns, which may be involved in the optimization of spatial arrangement of the transmitter release site and receptor, thereby serving as a new mechanism of synaptic plasticity.
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87
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Harper CB, Smillie KJ. Current molecular approaches to investigate pre-synaptic dysfunction. J Neurochem 2021; 157:107-129. [PMID: 33544872 DOI: 10.1111/jnc.15316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.
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Affiliation(s)
- Callista B Harper
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
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88
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Wu Z, Xu X, Xi P. Stimulated emission depletion microscopy for biological imaging in four dimensions: A review. Microsc Res Tech 2021; 84:1947-1958. [PMID: 33713513 DOI: 10.1002/jemt.23750] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 02/27/2021] [Indexed: 12/26/2022]
Abstract
Stimulated emission depletion (STED) microscopy allows high lateral and axial resolution, long term imaging in living cells. Here we review recent technical advances in STED microscopy, with emphasis on resolution and measurement range of XYZt four dimensions. Different STED technical advances and novel STED probes are discussed with their respective application in biological subcellular imaging. This review may serve as a practical guide for choosing a suitable approach to the advanced STED super-resolution imaging.
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Affiliation(s)
- Zhaoyang Wu
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China
| | - Xinzhu Xu
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China
| | - Peng Xi
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China.,UTS-SUSTech Joint Research Centre for Biomedical Materials and Devices, Department of Biomedical Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, China
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89
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The why and how of sleep-dependent synaptic down-selection. Semin Cell Dev Biol 2021; 125:91-100. [PMID: 33712366 PMCID: PMC8426406 DOI: 10.1016/j.semcdb.2021.02.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/28/2021] [Accepted: 02/28/2021] [Indexed: 12/22/2022]
Abstract
Sleep requires that we disconnect from the environment, losing the ability to promptly respond to stimuli. There must be at least one essential function that justifies why we take this risk every day, and that function must depend on the brain being offline. We have proposed that this function is to renormalize synaptic weights after learning has led to a net increase in synaptic strength in many brain circuits. Without this renormalization, synaptic activity would become energetically too expensive and saturation would prevent new learning. There is converging evidence from molecular, electrophysiological, and ultrastructural experiments showing a net increase in synaptic strength after the major wake phase, and a net decline after sleep. The evidence also suggests that sleep-dependent renormalization is a smart process of synaptic down-selection, comprehensive and yet specific, which could explain the many beneficial effects of sleep on cognition. Recently, a key molecular mechanism that allows broad synaptic weakening during sleep was identified. Other mechanisms still being investigated should eventually explain how sleep can weaken most synapses but afford protection to some, including those directly activated by learning. That synaptic down-selection takes place during sleep is by now established; why it should take place during sleep has a plausible explanation; how it happens is still work in progress.
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90
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Martinez-Sanchez A, Laugks U, Kochovski Z, Papantoniou C, Zinzula L, Baumeister W, Lučić V. Trans-synaptic assemblies link synaptic vesicles and neuroreceptors. SCIENCE ADVANCES 2021; 7:7/10/eabe6204. [PMID: 33674312 PMCID: PMC7935360 DOI: 10.1126/sciadv.abe6204] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 01/22/2021] [Indexed: 05/03/2023]
Abstract
Synaptic transmission is characterized by fast, tightly coupled processes and complex signaling pathways that require a precise protein organization, such as the previously reported nanodomain colocalization of pre- and postsynaptic proteins. Here, we used cryo-electron tomography to visualize synaptic complexes together with their native environment comprising interacting proteins and lipids on a 2- to 4-nm scale. Using template-free detection and classification, we showed that tripartite trans-synaptic assemblies (subcolumns) link synaptic vesicles to postsynaptic receptors and established that a particular displacement between directly interacting complexes characterizes subcolumns. Furthermore, we obtained de novo average structures of ionotropic glutamate receptors in their physiological composition, embedded in plasma membrane. These data support the hypothesis that synaptic function is carried by precisely organized trans-synaptic units. It provides a framework for further exploration of synaptic and other large molecular assemblies that link different cells or cellular regions and may require weak or transient interactions to exert their function.
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Affiliation(s)
- Antonio Martinez-Sanchez
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
- Department of Computer Sciences, Faculty of Sciences, University of Oviedo, Federico Garcia Lorca 18, 33007, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, University of Oviedo, Avenida Hospital Universitario s/n, 33011 Oviedo, Spain
- Institute of Neuropathology, University Medical Center Göttingen, 37075 Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Göttingen, Germany
| | - Ulrike Laugks
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Zdravko Kochovski
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Christos Papantoniou
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Luca Zinzula
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Vladan Lučić
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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91
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Ravalia AS, Lau J, Barron JC, Purchase SLM, Southwell AL, Hayden MR, Nafar F, Parsons MP. Super-resolution imaging reveals extrastriatal synaptic dysfunction in presymptomatic Huntington disease mice. Neurobiol Dis 2021; 152:105293. [PMID: 33556538 DOI: 10.1016/j.nbd.2021.105293] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 01/14/2021] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Synaptic structure and function are compromised prior to cell death and symptom onset in a variety of neurodegenerative diseases. In Huntington disease (HD), a CAG repeat expansion in the gene encoding the huntingtin protein results in a presymptomatic stage that typically spans multiple decades and is followed by striking degeneration of striatal tissue and the progression of debilitating motor symptoms. Many lines of evidence demonstrate that the HD presymptomatic window is associated with injurious effects to striatal synapses, many of which appear to be prerequisites to subsequent cell death. While the striatum is the most vulnerable region in the HD brain, it is widely recognized that HD is a brain-wide disease, affecting numerous extrastriatal regions that contribute to debilitating non-motor symptoms including cognitive dysfunction. Currently, we have a poor understanding of the synaptic integrity, or lack thereof, in extrastriatal regions in the presymptomatic HD brain. If early therapeutic intervention seeks to maintain healthy synaptic function, it is important to understand early HD-associated synaptopathy at a brain-wide, rather than striatal-exclusive, level. Here, we focused on the hippocampus as this structure is generally thought to be affected only in manifest HD despite the subtle cognitive deficits known to emerge in prodromal HD. We used super-resolution microscopy and multi-electrode array electrophysiology as sensitive measures of excitatory synapse structure and function, respectively, in the hippocampus of presymptomatic heterozygous HD mice (Q175FDN model). We found clear evidence for enhanced AMPA receptor subunit clustering and hyperexcitability well before the onset of a detectable HD-like behavioral phenotype. In addition, activity-dependent re-organization of synaptic protein nanostructure, and functional measures of synaptic plasticity were impaired in presymptomatic HD mice. These data demonstrate that synaptic abnormalities in the presymptomatic HD brain are not exclusive to the striatum, and highlight the need to better understand the region-dependent complexities of early synaptopathy in the HD brain.
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Affiliation(s)
- Adam S Ravalia
- Division of Biomedical Science, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - James Lau
- Division of Biomedical Science, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Jessica C Barron
- Division of Biomedical Science, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Stephanie L M Purchase
- Division of Biomedical Science, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Amber L Southwell
- University of Central Florida, College of Medicine, Burnett School of Biomedical Sciences, Orlando, FL, USA
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Firoozeh Nafar
- Division of Biomedical Science, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada
| | - Matthew P Parsons
- Division of Biomedical Science, Faculty of Medicine, Memorial University, St. John's, NL A1B 3V6, Canada.
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92
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Li S, Raychaudhuri S, Lee SA, Brockmann MM, Wang J, Kusick G, Prater C, Syed S, Falahati H, Ramos R, Bartol TM, Hosy E, Watanabe S. Asynchronous release sites align with NMDA receptors in mouse hippocampal synapses. Nat Commun 2021; 12:677. [PMID: 33514725 PMCID: PMC7846561 DOI: 10.1038/s41467-021-21004-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 01/08/2021] [Indexed: 01/30/2023] Open
Abstract
Neurotransmitter is released synchronously and asynchronously following an action potential. Our recent study indicates that the release sites of these two phases are segregated within an active zone, with asynchronous release sites enriched near the center in mouse hippocampal synapses. Here we demonstrate that synchronous and asynchronous release sites are aligned with AMPA receptor and NMDA receptor clusters, respectively. Computational simulations indicate that this spatial and temporal arrangement of release can lead to maximal membrane depolarization through AMPA receptors, alleviating the pore-blocking magnesium leading to greater activation of NMDA receptors. Together, these results suggest that release sites are likely organized to activate NMDA receptors efficiently.
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Affiliation(s)
- Shuo Li
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
- Department of Biological and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Sumana Raychaudhuri
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Stephen Alexander Lee
- Neurobiology Course, The Marine Biological Laboratory, Woods Hole, MA, USA
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Marisa M Brockmann
- Institute of Neurophysiology, Charité Universitätsmedizin, Berlin, Germany
| | - Jing Wang
- ThermoFisher Scientific, Hillsboro, OR, USA
| | - Grant Kusick
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
- Biochemistry, Cellular and Molecular Biology Graduate Program, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Christine Prater
- Neurobiology Course, The Marine Biological Laboratory, Woods Hole, MA, USA
- Department of Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Sarah Syed
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Hanieh Falahati
- Neurobiology Course, The Marine Biological Laboratory, Woods Hole, MA, USA
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Raul Ramos
- Neurobiology Course, The Marine Biological Laboratory, Woods Hole, MA, USA
- Department of Biology, Brandeis University, Waltham, MA, USA
| | - Tomas M Bartol
- Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Eric Hosy
- Centre National de la Recherche Scientifique, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, Bordeaux, France
| | - Shigeki Watanabe
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
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93
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Imaging of spine synapses using super-resolution microscopy. Anat Sci Int 2021; 96:343-358. [PMID: 33459976 DOI: 10.1007/s12565-021-00603-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 01/04/2021] [Indexed: 12/17/2022]
Abstract
Neuronal circuits in the neocortex and hippocampus are essential for higher brain functions such as motor learning and spatial memory. In the mammalian forebrain, most excitatory synapses of pyramidal neurons are formed on spines, which are tiny protrusions extending from the dendritic shaft. The spine contains specialized molecular machinery that regulates synaptic transmission and plasticity. Spine size correlates with the efficacy of synaptic transmission, and spine morphology affects signal transduction at the post-synaptic compartment. Plasticity-related changes in the structural and molecular organization of spine synapses are thought to underlie the cellular basis of learning and memory. Recent advances in super-resolution microscopy have revealed the molecular mechanisms of the nanoscale synaptic structures regulating synaptic transmission and plasticity in living neurons, which are difficult to investigate using electron microscopy alone. In this review, we summarize recent advances in super-resolution imaging of spine synapses and discuss the implications of nanoscale structures in the regulation of synaptic function, learning, and memory.
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94
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Volumetric live cell imaging with three-dimensional parallelized RESOLFT microscopy. Nat Biotechnol 2021; 39:609-618. [PMID: 33432197 DOI: 10.1038/s41587-020-00779-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 11/19/2020] [Indexed: 11/09/2022]
Abstract
Elucidating the volumetric architecture of organelles and molecules inside cells requires microscopy methods with a sufficiently high spatial resolution in all three dimensions. Current methods are limited by insufficient resolving power along the optical axis, long recording times and photobleaching when applied to live cell imaging. Here, we present a 3D, parallelized, reversible, saturable/switchable optical fluorescence transition (3D pRESOLFT) microscope capable of delivering sub-80-nm 3D resolution in whole living cells. We achieved rapid (1-2 Hz) acquisition of large fields of view (~40 × 40 µm2) by highly parallelized image acquisition with an interference pattern that creates an array of 3D-confined and equally spaced intensity minima. This allowed us to reversibly turn switchable fluorescent proteins to dark states, leading to a targeted 3D confinement of fluorescence. We visualized the 3D organization and dynamics of organelles in living cells and volumetric structural alterations of synapses during plasticity in cultured hippocampal neurons.
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95
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Carvalhais LG, Martinho VC, Ferreiro E, Pinheiro PS. Unraveling the Nanoscopic Organization and Function of Central Mammalian Presynapses With Super-Resolution Microscopy. Front Neurosci 2021; 14:578409. [PMID: 33584169 PMCID: PMC7874199 DOI: 10.3389/fnins.2020.578409] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 12/03/2020] [Indexed: 12/22/2022] Open
Abstract
The complex, nanoscopic scale of neuronal function, taking place at dendritic spines, axon terminals, and other minuscule structures, cannot be adequately resolved using standard, diffraction-limited imaging techniques. The last couple of decades saw a rapid evolution of imaging methods that overcome the diffraction limit imposed by Abbe's principle. These techniques, including structured illumination microscopy (SIM), stimulated emission depletion (STED), photo-activated localization microscopy (PALM), and stochastic optical reconstruction microscopy (STORM), among others, have revolutionized our understanding of synapse biology. By exploiting the stochastic nature of fluorophore light/dark states or non-linearities in the interaction of fluorophores with light, by using modified illumination strategies that limit the excitation area, these methods can achieve spatial resolutions down to just a few tens of nm or less. Here, we review how these advanced imaging techniques have contributed to unprecedented insight into the nanoscopic organization and function of mammalian neuronal presynapses, revealing new organizational principles or lending support to existing views, while raising many important new questions. We further discuss recent technical refinements and newly developed tools that will continue to expand our ability to delve deeper into how synaptic function is orchestrated at the nanoscopic level.
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Affiliation(s)
- Lia G Carvalhais
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Vera C Martinho
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Elisabete Ferreiro
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Paulo S Pinheiro
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Coimbra, Portugal.,Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
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96
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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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97
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Smart K, Nagano-Saito A, Milella MS, Sakae DY, Favier M, Vigneault E, Louie L, Hamilton A, Ferguson SSG, Rosa-Neto P, Narayanan S, El Mestikawy S, Leyton M, Benkelfat C. Metabotropic glutamate type 5 receptor binding availability during dextroamphetamine sensitization in mice and humans. J Psychiatry Neurosci 2021; 46:E1-E13. [PMID: 32559027 PMCID: PMC7955855 DOI: 10.1503/jpn.190162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Glutamate transmission is implicated in drug-induced behavioural sensitization and the associated long-lasting increases in mesolimbic output. Metabotropic glutamate type 5 (mGlu5) receptors might be particularly important, but most details are poorly understood. METHODS We first assessed in mice (n = 51, all male) the effects of repeated dextroamphetamine administration (2.0 mg/kg, i.p.) on locomotor activity and binding of the mGlu5 ligand [3H]ABP688. In a parallel study, in 19 stimulant-drug-naïve healthy human volunteers (14 female) we administered 3 doses of dextroamphetamine (0.3 mg/kg, p.o.) or placebo, followed by a fourth dose 2 weeks later. We measured [11C]ABP688 binding using positron emission tomography before and after the induction phase. We assessed psychomotor and behavioural sensitization using speech rate, eye blink rate and self-report. We measured the localization of mGlu5 relative to synaptic markers in mouse striatum using immunofluorescence. RESULTS We observed amphetamine-induced psychomotor sensitization in mice and humans. We did not see group differences in mGlu5 availability following 3 pre-challenge amphetamine doses, but group differences did develop in mice administered 5 doses. In mice and humans, individual differences in mGlu5 binding after repeated amphetamine administration were negatively correlated with the extent of behavioural sensitization. In drug-naïve mice, mGlu5 was expressed at 67% of excitatory synapses on dendrites of striatal medium spiny neur. LIMITATIONS Correlational results should be interpreted as suggestive because of the limited sample size. We did not assess sex differences. CONCLUSION Together, these results suggest that changes in mGlu5 availability are not part of the earliest neural adaptations in stimulant-induced behavioural sensitization, but low mGlu5 binding might identify a higher propensity for sensitization.
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Affiliation(s)
- Kelly Smart
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Atsuko Nagano-Saito
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Michele S Milella
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Diana Yae Sakae
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Mathieu Favier
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Erika Vigneault
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Leanne Louie
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Alison Hamilton
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Stephen S G Ferguson
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Pedro Rosa-Neto
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Sridar Narayanan
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Salah El Mestikawy
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Marco Leyton
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
| | - Chawki Benkelfat
- From the Department of Psychiatry, McGill University, Montreal, Que. (Smart, Nagano-Saito, Milella, Sakae, Favier, Vigneault, Louie, Rosa-Neto, El Mestikawy, Leyton, Benkelfat); the Douglas Mental Health University Institute, McGill University, Montreal, Que. (Smart, Sakae, Favier, Vigneault, Rosa-Neto, El Mestikawy); the Department of Cellular and Molecular Medicine, University of Ottawa, Ont. (Hamilton, Ferguson); the McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); the Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Que. (Rosa-Neto, Narayanan, Leyton, Benkelfat); and the Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Que. (Leyton)
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98
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Hakim V, Ranft J. Lifetime of a structure evolving by cluster aggregation and particle loss, and application to postsynaptic scaffold domains. Phys Rev E 2020; 101:012411. [PMID: 32069640 DOI: 10.1103/physreve.101.012411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 01/21/2023]
Abstract
The dynamics of several mesoscopic biological structures depend on the interplay of growth through the incorporation of components of different sizes laterally diffusing along the cell membrane, and loss by component turnover. In particular, a model of such an out-of-equilibrium dynamics has recently been proposed for postsynaptic scaffold domains, which are key structures of neuronal synapses. It is of interest to estimate the lifetime of these mesoscopic structures, especially in the context of synapses where this time is related to memory retention. The lifetime of a structure can be very long as compared to the turnover time of its components and it can be difficult to estimate it by direct numerical simulations. Here, in the context of the model proposed for postsynaptic scaffold domains, we approximate the aggregation-turnover dynamics by a shot-noise process. This enables us to analytically compute the quasistationary distribution describing the sizes of the surviving structures as well as their characteristic lifetime. We show that our analytical estimate agrees with numerical simulations of a full spatial model, in a regime of parameters where a direct assessment is computationally feasible. We then use our approach to estimate the lifetime of mesoscopic structures in parameter regimes where computer simulations would be prohibitively long. For gephyrin, the scaffolding protein specific to inhibitory synapses, we estimate a lifetime longer than several months for a scaffold domain when the single gephyrin protein turnover time is about half an hour, as experimentally measured. While our focus is on postsynaptic domains, our formalism and techniques should be applicable to other biological structures that are also formed by a balance of condensation and turnover.
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Affiliation(s)
- Vincent Hakim
- Laboratoire de Physique de l'Ecole Normale Supérieure, CNRS, Ecole Normale Supérieure, PSL University, Sorbonne Université, Université Paris-Diderot, Paris, France
| | - Jonas Ranft
- Institut de Biologie de l'ENS (IBENS), Ecole Normale Supérieure, PSL University, CNRS, INSERM, Paris, France
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99
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Park CE, Cho Y, Cho I, Jung H, Kim B, Shin JH, Choi S, Kwon SK, Hahn YK, Chang JB. Super-Resolution Three-Dimensional Imaging of Actin Filaments in Cultured Cells and the Brain via Expansion Microscopy. ACS NANO 2020; 14:14999-15010. [PMID: 33095573 DOI: 10.1021/acsnano.0c04915] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Actin is an essential protein in almost all life forms. It mediates diverse biological functions, ranging from controlling the shape of cells and cell movements to cargo transport and the formation of synaptic connections. Multiple diseases are closely related to the dysfunction of actin or actin-related proteins. Despite the biological importance of actin, super-resolution imaging of it in tissue is still challenging, as it forms very dense networks in almost all cells inside the tissue. In this work, we demonstrate multiplexed super-resolution volumetric imaging of actin in both cultured cells and mouse brain slices via expansion microscopy (ExM). By introducing a simple labeling process, which enables the anchoring of an actin probe, phalloidin, to a swellable hydrogel, the multiplexed ExM imaging of actin filaments was achieved. We first showed that this technique could visualize the nanoscale details of actin filament organizations in cultured cells. Then, we applied this technique to mouse brain slices and visualized diverse actin organizations, such as the parallel actin filaments along the long axis of dendrites and dense actin structures in postsynaptic spines. We examined the postsynaptic spines in the mouse brain and showed that the organizations of actin filaments are highly diverse. This technique, which enables the high-throughput 60 nm resolution imaging of actin filaments and other proteins in cultured cells and thick tissue slices, would be a useful tool to study the organization of actin filaments in diverse biological circumstances and how they change under pathological conditions.
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Affiliation(s)
- Chan E Park
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Youngbin Cho
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - In Cho
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Hyunsu Jung
- Division of Life Sciences, Korea University, Seoul 02841, Korea
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Byeongyeon Kim
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Korea
| | - Jennifer H Shin
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Sungyoung Choi
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Korea
| | - Seok-Kyu Kwon
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea
- Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Seoul 02792, Korea
| | - Young Ki Hahn
- Biomedical Convergence Science & Technology, Industrial Technology Advances, Kyungpook National University, Daegu 41566, Korea
| | - Jae-Byum Chang
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- KI for Health Science and Technology, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
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100
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Wiesner T, Bilodeau A, Bernatchez R, Deschênes A, Raulier B, De Koninck P, Lavoie-Cardinal F. Activity-Dependent Remodeling of Synaptic Protein Organization Revealed by High Throughput Analysis of STED Nanoscopy Images. Front Neural Circuits 2020; 14:57. [PMID: 33177994 PMCID: PMC7594516 DOI: 10.3389/fncir.2020.00057] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 07/29/2020] [Indexed: 01/03/2023] Open
Abstract
The organization of proteins in the apposed nanodomains of pre- and postsynaptic compartments is thought to play a pivotal role in synaptic strength and plasticity. As such, the alignment between pre- and postsynaptic proteins may regulate, for example, the rate of presynaptic release or the strength of postsynaptic signaling. However, the analysis of these structures has mainly been restricted to subsets of synapses, providing a limited view of the diversity of synaptic protein cluster remodeling during synaptic plasticity. To characterize changes in the organization of synaptic nanodomains during synaptic plasticity over a large population of synapses, we combined STimulated Emission Depletion (STED) nanoscopy with a Python-based statistical object distance analysis (pySODA), in dissociated cultured hippocampal circuits exposed to treatments driving different forms of synaptic plasticity. The nanoscale organization, characterized in terms of coupling properties, of presynaptic (Bassoon, RIM1/2) and postsynaptic (PSD95, Homer1c) scaffold proteins was differently altered in response to plasticity-inducing stimuli. For the Bassoon - PSD95 pair, treatments driving synaptic potentiation caused an increase in their coupling probability, whereas a stimulus driving synaptic depression had an opposite effect. To enrich the characterization of the synaptic cluster remodeling at the population level, we applied unsupervised machine learning approaches to include selected morphological features into a multidimensional analysis. This combined analysis revealed a large diversity of synaptic protein cluster subtypes exhibiting differential activity-dependent remodeling, yet with common features depending on the expected direction of plasticity. The expanded palette of synaptic features revealed by our unbiased approach should provide a basis to further explore the widely diverse molecular mechanisms of synaptic plasticity.
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Affiliation(s)
| | | | | | | | | | - Paul De Koninck
- CERVO Brain Research Centre, Québec, QC, Canada.,Department of Biochemistry, Microbiology and Bioinformatics, Université Laval, Québec, QC, Canada
| | - Flavie Lavoie-Cardinal
- CERVO Brain Research Centre, Québec, QC, Canada.,Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada
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