1
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Wu H, Chen X, Shen Z, Li H, Liang S, Lu Y, Zhang M. Phosphorylation-dependent membraneless organelle fusion and fission illustrated by postsynaptic density assemblies. Mol Cell 2024; 84:309-326.e7. [PMID: 38096828 DOI: 10.1016/j.molcel.2023.11.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 09/10/2023] [Accepted: 11/13/2023] [Indexed: 01/21/2024]
Abstract
Membraneless organelles formed by phase separation of proteins and nucleic acids play diverse cellular functions. Whether and, if yes, how membraneless organelles in ways analogous to membrane-based organelles also undergo regulated fusion and fission is unknown. Here, using a partially reconstituted mammalian postsynaptic density (PSD) condensate as a paradigm, we show that membraneless organelles can undergo phosphorylation-dependent fusion and fission. Without phosphorylation of the SAPAP guanylate kinase domain-binding repeats, the upper and lower layers of PSD protein mixtures form two immiscible sub-compartments in a phase-in-phase organization. Phosphorylation of SAPAP leads to fusion of the two sub-compartments into one condensate accompanied with an increased Stargazin density in the condensate. Dephosphorylation of SAPAP can reverse this event. Preventing SAPAP phosphorylation in vivo leads to increased separation of proteins from the lower and upper layers of PSD sub-compartments. Thus, analogous to membrane-based organelles, membraneless organelles can also undergo regulated fusion and fission.
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Affiliation(s)
- Haowei 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
| | - Xudong Chen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zeyu Shen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Hao Li
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Shiqi Liang
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Youming Lu
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Mingjie Zhang
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518036, China; School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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2
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Rimbault C, Breillat C, Compans B, Toulmé E, Vicente FN, Fernandez-Monreal M, Mascalchi P, Genuer C, Puente-Muñoz V, Gauthereau I, Hosy E, Claverol S, Giannone G, Chamma I, Mackereth CD, Poujol C, Choquet D, Sainlos M. Engineering paralog-specific PSD-95 recombinant binders as minimally interfering multimodal probes for advanced imaging techniques. eLife 2024; 13:e69620. [PMID: 38167295 PMCID: PMC10803022 DOI: 10.7554/elife.69620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 12/04/2023] [Indexed: 01/05/2024] Open
Abstract
Despite the constant advances in fluorescence imaging techniques, monitoring endogenous proteins still constitutes a major challenge in particular when considering dynamics studies or super-resolution imaging. We have recently evolved specific protein-based binders for PSD-95, the main postsynaptic scaffold proteins at excitatory synapses. Since the synthetic recombinant binders recognize epitopes not directly involved in the target protein activity, we consider them here as tools to develop endogenous PSD-95 imaging probes. After confirming their lack of impact on PSD-95 function, we validated their use as intrabody fluorescent probes. We further engineered the probes and demonstrated their usefulness in different super-resolution imaging modalities (STED, PALM, and DNA-PAINT) in both live and fixed neurons. Finally, we exploited the binders to enrich at the synapse genetically encoded calcium reporters. Overall, we demonstrate that these evolved binders constitute a robust and efficient platform to selectively target and monitor endogenous PSD-95 using various fluorescence imaging techniques.
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Affiliation(s)
- Charlotte Rimbault
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Christelle Breillat
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Benjamin Compans
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Estelle Toulmé
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Filipe Nunes Vicente
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Monica Fernandez-Monreal
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4BordeauxFrance
| | - Patrice Mascalchi
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4BordeauxFrance
| | - Camille Genuer
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Virginia Puente-Muñoz
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Isabel Gauthereau
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Eric Hosy
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | | | - Gregory Giannone
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Ingrid Chamma
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | | | - Christel Poujol
- University of Bordeaux, CNRS, INSERM, Bordeaux Imaging Center, BIC, UMS 3420, US 4BordeauxFrance
| | - Daniel Choquet
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
| | - Matthieu Sainlos
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297BordeauxFrance
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3
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Romero H, Schmidt A, Cardoso CM. Protein Level Quantification Across Fluorescence-based Platforms. Bio Protoc 2023; 13:e4834. [PMID: 37817905 PMCID: PMC10560694 DOI: 10.21769/bioprotoc.4834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 08/02/2023] [Accepted: 08/02/2023] [Indexed: 10/12/2023] Open
Abstract
Biological processes are dependent on protein concentration and there is an inherent variability among cells even in environment-controlled conditions. Determining the amount of protein of interest in a cell is relevant to quantitatively relate it with the cells (patho)physiology. Previous studies used either western blot to determine the average amount of protein per cell in a population or fluorescence intensity to provide a relative amount of protein. This method combines both techniques. First, the protein of interest is purified, and its concentration determined. Next, cells containing the protein of interest with a fluorescent tag are sorted into different levels of intensity using fluorescence-activated cell sorting, and the amount of protein for each intensity category is calculated using the purified protein as calibration. Lastly, a calibration curve allows the direct relation of the amount of protein to the intensity levels determined with any instrument able to measure intensity levels. Once a fluorescence-based instrument is calibrated, it is possible to determine protein concentrations based on intensity. Key features • This method allows the evaluation and comparison of protein concentration in cells based on fluorescence intensity. • Requires protein purification and fluorescence-activated cell sorting. • Once calibrated for one protein, it allows determination of the levels of this protein using any fluorescence-based instrument. • Allows to determine subcellular local protein concentration based on combining volumetric and intensity measurements.
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Affiliation(s)
- Hector Romero
- Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Annika Schmidt
- Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Cristina M. Cardoso
- Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
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4
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Yamada R, Takada S. Postsynaptic protein assembly in three and two dimensions studied by mesoscopic simulations. Biophys J 2023; 122:3395-3410. [PMID: 37496268 PMCID: PMC10465727 DOI: 10.1016/j.bpj.2023.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/25/2023] [Accepted: 07/21/2023] [Indexed: 07/28/2023] Open
Abstract
Recently, cellular biomolecular condensates formed via phase separation have received considerable attention. While they can be formed either in cytosol (denoted as 3D) or beneath the membrane (2D), the underlying difference between the two has not been well clarified. To compare the phase behaviors in 3D and 2D, postsynaptic density (PSD) serves as a model system. PSD is a protein condensate located under the postsynaptic membrane that influences the localization of glutamate receptors and thus contributes to synaptic plasticity. Recent in vitro studies have revealed the formation of droplets of various soluble PSD proteins via liquid-liquid phase separation. However, it is unclear how these protein condensates are formed beneath the membrane and how they specifically affect the localization of glutamate receptors in the membrane. In this study, focusing on the mixture of a glutamate receptor complex, AMPAR-TARP, and a ubiquitous scaffolding protein, PSD-95, we constructed a mesoscopic model of protein-domain interactions in PSD and performed comparative molecular simulations. The results showed a sharp contrast in the phase behaviors of protein assemblies in 3D and those under the membrane (2D). A mixture of a soluble variant of the AMPAR-TARP complex and PSD-95 in the 3D system resulted in a phase-separated condensate, which was consistent with the experimental results. However, with identical domain interactions, AMPAR-TARP embedded in the membrane formed clusters with PSD-95, but did not form a stable separated phase. Thus, the cluster formation behaviors of PSD proteins in the 3D and 2D systems were distinct. The current study suggests that, more generally, stable phase separation can be more difficult to achieve in and beneath the membrane than in 3D systems.
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Affiliation(s)
- Risa Yamada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan.
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5
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Rodrigues YE, Tigaret CM, Marie H, O'Donnell C, Veltz R. A stochastic model of hippocampal synaptic plasticity with geometrical readout of enzyme dynamics. eLife 2023; 12:e80152. [PMID: 37589251 PMCID: PMC10435238 DOI: 10.7554/elife.80152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 03/22/2023] [Indexed: 08/18/2023] Open
Abstract
Discovering the rules of synaptic plasticity is an important step for understanding brain learning. Existing plasticity models are either (1) top-down and interpretable, but not flexible enough to account for experimental data, or (2) bottom-up and biologically realistic, but too intricate to interpret and hard to fit to data. To avoid the shortcomings of these approaches, we present a new plasticity rule based on a geometrical readout mechanism that flexibly maps synaptic enzyme dynamics to predict plasticity outcomes. We apply this readout to a multi-timescale model of hippocampal synaptic plasticity induction that includes electrical dynamics, calcium, CaMKII and calcineurin, and accurate representation of intrinsic noise sources. Using a single set of model parameters, we demonstrate the robustness of this plasticity rule by reproducing nine published ex vivo experiments covering various spike-timing and frequency-dependent plasticity induction protocols, animal ages, and experimental conditions. Our model also predicts that in vivo-like spike timing irregularity strongly shapes plasticity outcome. This geometrical readout modelling approach can be readily applied to other excitatory or inhibitory synapses to discover their synaptic plasticity rules.
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Affiliation(s)
- Yuri Elias Rodrigues
- Université Côte d’AzurNiceFrance
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRSValbonneFrance
- Inria Center of University Côte d’Azur (Inria)Sophia AntipolisFrance
| | - Cezar M Tigaret
- Neuroscience and Mental Health Research Innovation Institute, Division of Psychological Medicine and Clinical Neurosciences,School of Medicine, Cardiff UniversityCardiffUnited Kingdom
| | - Hélène Marie
- Université Côte d’AzurNiceFrance
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRSValbonneFrance
| | - Cian O'Donnell
- School of Computing, Engineering, and Intelligent Systems, Magee Campus, Ulster UniversityLondonderryUnited Kingdom
- School of Computer Science, Electrical and Electronic Engineering, and Engineering Mathematics, University of BristolBristolUnited Kingdom
| | - Romain Veltz
- Inria Center of University Côte d’Azur (Inria)Sophia AntipolisFrance
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6
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Zhang Q, Miyamoto A, Watanabe S, Arimori T, Sakai M, Tomisaki M, Kiuchi T, Takagi J, Watanabe N. Engineered fast-dissociating antibody fragments for multiplexed super-resolution microscopy. CELL REPORTS METHODS 2022; 2:100301. [PMID: 36313806 PMCID: PMC9606137 DOI: 10.1016/j.crmeth.2022.100301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 07/07/2022] [Accepted: 08/31/2022] [Indexed: 05/22/2023]
Abstract
Image reconstruction by integrating exchangeable single-molecule localization (IRIS) achieves multiplexed super-resolution imaging by high-density labeling with fast exchangeable fluorescent probes. However, previous methods to develop probes for individual targets required a great amount of time and effort. Here, we introduce a method for generating recombinant IRIS probes with a new mutagenesis strategy that can be widely applied to existing antibody sequences. Several conserved tyrosine residues at the base of complementarity-determining regions were identified as candidate sites for site-directed mutagenesis. With a high probability, mutations at candidate sites accelerated the off rate of recombinant antibody-based probes without compromising specific binding. We were able to develop IRIS probes from five monoclonal antibodies and three single-domain antibodies. We demonstrate multiplexed localization of endogenous proteins in primary neurons that visualizes small synaptic connections with high binding density. It is now practically feasible to generate fast-dissociating fluorescent probes for multitarget super-resolution imaging.
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Affiliation(s)
- Qianli Zhang
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan
| | - Akitoshi Miyamoto
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan
| | - Shin Watanabe
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan
| | - Takao Arimori
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Masanori Sakai
- Kyoto University Faculty of Engineering, Kyoto 606-8317, Japan
| | - Madoka Tomisaki
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan
| | - Tai Kiuchi
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Junichi Takagi
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Naoki Watanabe
- Laboratory of Single-Molecule Cell Biology, Kyoto University Graduate School of Biostudies, Kyoto 606-8501, Japan
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
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7
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Chen X, Kuner T, Blanpied TA. Editorial: Quantifying and controlling the nano-architecture of neuronal synapses. Front Synaptic Neurosci 2022; 14:1024073. [PMID: 36160915 PMCID: PMC9491271 DOI: 10.3389/fnsyn.2022.1024073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Xiaobing Chen
- Laboratory of Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Xiaobing Chen
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
- Thomas Kuner
| | - Thomas A. Blanpied
- School of Medicine, University of Maryland, Baltimore, MD, United States
- Thomas A. Blanpied
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8
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Parisutham V, Chhabra S, Ali MZ, Brewster RC. Tunable transcription factor library for robust quantification of regulatory properties in Escherichia coli. Mol Syst Biol 2022; 18:e10843. [PMID: 35694815 PMCID: PMC9189660 DOI: 10.15252/msb.202110843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 11/12/2022] Open
Abstract
Predicting the quantitative regulatory function of transcription factors (TFs) based on factors such as binding sequence, binding location, and promoter type is not possible. The interconnected nature of gene networks and the difficulty in tuning individual TF concentrations make the isolated study of TF function challenging. Here, we present a library of Escherichia coli strains designed to allow for precise control of the concentration of individual TFs enabling the study of the role of TF concentration on physiology and regulation. We demonstrate the usefulness of this resource by measuring the regulatory function of the zinc-responsive TF, ZntR, and the paralogous TF pair, GalR/GalS. For ZntR, we find that zinc alters ZntR regulatory function in a way that enables activation of the regulated gene to be robust with respect to ZntR concentration. For GalR and GalS, we are able to demonstrate that these paralogous TFs have fundamentally distinct regulatory roles beyond differences in binding affinity.
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Affiliation(s)
- Vinuselvi Parisutham
- Department of Systems BiologyUniversity of Massachusetts Chan Medical SchoolWorcesterMAUSA
| | - Shivani Chhabra
- Department of Pharmacological SciencesIcahn School of Medicine at Mount SinaiNew YorkNYUSA
| | - Md Zulfikar Ali
- Department of Systems BiologyUniversity of Massachusetts Chan Medical SchoolWorcesterMAUSA
| | - Robert C Brewster
- Department of Systems BiologyUniversity of Massachusetts Chan Medical SchoolWorcesterMAUSA
- Department of Microbiology and Physiological SystemsUniversity of Massachusetts Chan Medical SchoolWorcesterMAUSA
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9
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O-GlcNAcylation modulates liquid–liquid phase separation of SynGAP/PSD-95. Nat Chem 2022; 14:831-840. [DOI: 10.1038/s41557-022-00946-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 04/07/2022] [Indexed: 12/13/2022]
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10
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Stillman M, Lautz JD, Johnson RS, MacCoss MJ, Smith SEP. Activity dependent dissociation of the Homer1 interactome. Sci Rep 2022; 12:3207. [PMID: 35217690 PMCID: PMC8881602 DOI: 10.1038/s41598-022-07179-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 02/09/2022] [Indexed: 11/12/2022] Open
Abstract
Neurons encode information by rapidly modifying synaptic protein complexes, which changes the strength of specific synaptic connections. Homer1 is abundantly expressed at glutamatergic synapses, and is known to alter its binding to metabotropic glutamate receptor 5 (mGlu5) in response to synaptic activity. However, Homer participates in many additional known interactions whose activity-dependence is unclear. Here, we used co-immunoprecipitation and label-free quantitative mass spectrometry to characterize activity-dependent interactions in the cerebral cortex of wildtype and Homer1 knockout mice. We identified a small, high-confidence protein network consisting of mGlu5, Shank2 and 3, and Homer1–3, of which only mGlu5 and Shank3 were significantly reduced following neuronal depolarization. We identified several other proteins that reduced their co-association in an activity-dependent manner, likely mediated by Shank proteins. We conclude that Homer1 dissociates from mGlu5 and Shank3 following depolarization, but our data suggest that direct Homer1 interactions in the cortex may be more limited than expected.
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Affiliation(s)
- Mason Stillman
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA.,Dartmouth-Hitchcock Medical Center Psychiatry Residency Program, Dartmouth, NH, USA
| | - Jonathan D Lautz
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Richard S Johnson
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Michael J MacCoss
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Stephen E P Smith
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA. .,Department of Pediatrics, University of Washington, Seattle, WA, USA. .,Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA.
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11
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Hosokawa T, Liu PW. Regulation of the Stability and Localization of Post-synaptic Membrane Proteins by Liquid-Liquid Phase Separation. Front Physiol 2021; 12:795757. [PMID: 34975543 PMCID: PMC8716852 DOI: 10.3389/fphys.2021.795757] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 11/17/2021] [Indexed: 12/01/2022] Open
Abstract
Synaptic plasticity is a cellular mechanism of learning and memory. The synaptic strength can be persistently upregulated or downregulated to update the information sent to the neuronal network and form a memory engram. For its molecular mechanism, the stability of α-amino-3-hydroxyl-5-methyl-4-isoxazolepropionate-type glutamate receptor (AMPAR), a glutamatergic ionotropic receptor, on the postsynaptic membrane has been studied for these two decades. Since AMPAR is not saturated on the postsynaptic membrane during a single event of neurotransmitter release, the number and nanoscale localization of AMPAR is critical for regulating the efficacy of synaptic transmission. The observation of AMPAR on the postsynaptic membrane by super-resolution microscopy revealed that AMPAR forms a nanodomain that is defined as a stable segregated cluster on the postsynaptic membrane to increase the efficacy of synaptic transmission. Postsynaptic density (PSD), an intracellular protein condensate underneath the postsynaptic membrane, regulates AMPAR dynamics via the intracellular domain of Stargazin, an auxiliary subunit of AMPAR. Recently, it was reported that PSD is organized by liquid-liquid phase separation (LLPS) to form liquid-like protein condensates. Furthermore, the calcium signal induced by the learning event triggers the persistent formation of sub-compartments of different protein groups inside protein condensates. This explains the formation of nanodomains via synaptic activation. The liquid-like properties of LLPS protein condensates are ideal for the molecular mechanism of synaptic plasticity. In this review, we summarize the recent progress in the properties and regulation of synaptic plasticity, postsynaptic receptors, PSD, and LLPS.
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12
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Cullinan MM, Klipp RC, Bankston JR. Regulation of acid-sensing ion channels by protein binding partners. Channels (Austin) 2021; 15:635-647. [PMID: 34704535 PMCID: PMC8555555 DOI: 10.1080/19336950.2021.1976946] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are a family of proton-gated cation channels that contribute to a diverse array of functions including pain sensation, cell death during ischemia, and more broadly to neurotransmission in the central nervous system. There is an increasing interest in understanding the physiological regulatory mechanisms of this family of channels. ASICs have relatively short N- and C-termini, yet a number of proteins have been shown to interact with these domains both in vitro and in vivo. These proteins can impact ASIC gating, localization, cell-surface expression, and regulation. Like all ion channels, it is important to understand the cellular context under which ASICs function in neurons and other cells. Here we will review what is known about a number of these potentially important regulatory molecules.
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Affiliation(s)
- Megan M Cullinan
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Robert C Klipp
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - John R Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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13
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Farahi N, Lazar T, Wodak SJ, Tompa P, Pancsa R. Integration of Data from Liquid-Liquid Phase Separation Databases Highlights Concentration and Dosage Sensitivity of LLPS Drivers. Int J Mol Sci 2021; 22:ijms22063017. [PMID: 33809541 PMCID: PMC8002189 DOI: 10.3390/ijms22063017] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/12/2021] [Accepted: 03/13/2021] [Indexed: 12/13/2022] Open
Abstract
Liquid–liquid phase separation (LLPS) is a molecular process that leads to the formation of membraneless organelles, representing functionally specialized liquid-like cellular condensates formed by proteins and nucleic acids. Integrating the data on LLPS-associated proteins from dedicated databases revealed only modest agreement between them and yielded a high-confidence dataset of 89 human LLPS drivers. Analysis of the supporting evidence for our dataset uncovered a systematic and potentially concerning difference between protein concentrations used in a good fraction of the in vitro LLPS experiments, a key parameter that governs the phase behavior, and the proteomics-derived cellular abundance levels of the corresponding proteins. Closer scrutiny of the underlying experimental data enabled us to offer a sound rationale for this systematic difference, which draws on our current understanding of the cellular organization of the proteome and the LLPS process. In support of this rationale, we find that genes coding for our human LLPS drivers tend to be dosage-sensitive, suggesting that their cellular availability is tightly regulated to preserve their functional role in direct or indirect relation to condensate formation. Our analysis offers guideposts for increasing agreement between in vitro and in vivo studies, probing the roles of proteins in LLPS.
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Affiliation(s)
- Nazanin Farahi
- VIB-VUB Center for Structural Biology, Flemish Institute for Biotechnology, 1050 Brussels, Belgium; (N.F.); (T.L.); (S.J.W.)
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
- Department of Biology, Technical University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Tamas Lazar
- VIB-VUB Center for Structural Biology, Flemish Institute for Biotechnology, 1050 Brussels, Belgium; (N.F.); (T.L.); (S.J.W.)
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Shoshana J. Wodak
- VIB-VUB Center for Structural Biology, Flemish Institute for Biotechnology, 1050 Brussels, Belgium; (N.F.); (T.L.); (S.J.W.)
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
| | - Peter Tompa
- VIB-VUB Center for Structural Biology, Flemish Institute for Biotechnology, 1050 Brussels, Belgium; (N.F.); (T.L.); (S.J.W.)
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary
- Correspondence: (P.T.); (R.P.)
| | - Rita Pancsa
- Institute of Enzymology, Research Centre for Natural Sciences, 1117 Budapest, Hungary
- Correspondence: (P.T.); (R.P.)
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14
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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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15
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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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16
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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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17
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OUP accepted manuscript. Microscopy (Oxf) 2021; 71:i72-i80. [DOI: 10.1093/jmicro/dfab048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/18/2021] [Accepted: 01/24/2022] [Indexed: 11/14/2022] Open
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18
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Tanaka S, Masuda Y, Harada A, Okabe S. Impaired actin dynamics and suppression of Shank2-mediated spine enlargement in cortactin knockout mice. ACTA ACUST UNITED AC 2020; 69:44-52. [PMID: 31990031 DOI: 10.1093/jmicro/dfaa001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 01/05/2020] [Accepted: 01/06/2020] [Indexed: 12/22/2022]
Abstract
Cortactin regulates actin polymerization and stabilizes branched actin network. In neurons, cortactin is enriched in dendritic spines that contain abundant actin polymers. To explore the function of cortactin in dendritic spines, we examined spine morphology and dynamics in cultured neurons taken from cortactin knockout (KO) mice. Histological analysis revealed that the density and morphology of dendritic spines were not significantly different between wild-type (WT) and cortactin KO neurons. Time-lapse imaging of hippocampal slice cultures showed that the extent of spine volume change was similar between WT and cortactin KO neurons. Despite little effect of cortactin deletion on spine morphology and dynamics, actin turnover in dendritic spines was accelerated in cortactin KO neurons. Furthermore, we detected a suppressive effect of cortactin KO on spine head size under the condition of excessive spine enlargement induced by overexpression of a prominent postsynaptic density protein Shank2. These results suggest that cortactin may have a role in maintaining actin organization by stabilizing actin filaments near the postsynaptic density.
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Affiliation(s)
- Shinji Tanaka
- Department of Cellular Neurobiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yasutaka Masuda
- Department of Cellular Neurobiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
| | - Akihiro Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan
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19
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Twenty Years of SynGAP Research: From Synapses to Cognition. J Neurosci 2020; 40:1596-1605. [PMID: 32075947 DOI: 10.1523/jneurosci.0420-19.2020] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/03/2020] [Accepted: 01/07/2020] [Indexed: 12/11/2022] Open
Abstract
SynGAP is a potent regulator of biochemical signaling in neurons and plays critical roles in neuronal function. It was first identified in 1998, and has since been extensively characterized as a mediator of synaptic plasticity. Because of its involvement in synaptic plasticity, SynGAP has emerged as a critical protein for normal cognitive function. In recent years, mutations in the SYNGAP1 gene have been shown to cause intellectual disability in humans and have been linked to other neurodevelopmental disorders, such as autism spectrum disorders and schizophrenia. While the structure and biochemical function of SynGAP have been well characterized, a unified understanding of the various roles of SynGAP at the synapse and its contributions to neuronal function remains to be achieved. In this review, we summarize and discuss the current understanding of the multifactorial role of SynGAP in regulating neuronal function gathered over the last two decades.
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20
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Ferrini F, Perez-Sanchez J, Ferland S, Lorenzo LE, Godin AG, Plasencia-Fernandez I, Cottet M, Castonguay A, Wang F, Salio C, Doyon N, Merighi A, De Koninck Y. Differential chloride homeostasis in the spinal dorsal horn locally shapes synaptic metaplasticity and modality-specific sensitization. Nat Commun 2020; 11:3935. [PMID: 32769979 PMCID: PMC7414850 DOI: 10.1038/s41467-020-17824-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 07/22/2020] [Indexed: 02/06/2023] Open
Abstract
GABAA/glycine-mediated neuronal inhibition critically depends on intracellular chloride (Cl-) concentration which is mainly regulated by the K+-Cl- co-transporter 2 (KCC2) in the adult central nervous system (CNS). KCC2 heterogeneity thus affects information processing across CNS areas. Here, we uncover a gradient in Cl- extrusion capacity across the superficial dorsal horn (SDH) of the spinal cord (laminae I-II: LI-LII), which remains concealed under low Cl- load. Under high Cl- load or heightened synaptic drive, lower Cl- extrusion is unveiled in LI, as expected from the gradient in KCC2 expression found across the SDH. Blocking TrkB receptors increases KCC2 in LI, pointing to differential constitutive TrkB activation across laminae. Higher Cl- lability in LI results in rapidly collapsing inhibition, and a form of activity-dependent synaptic plasticity expressed as a continuous facilitation of excitatory responses. The higher metaplasticity in LI as compared to LII differentially affects sensitization to thermal and mechanical input. Thus, inconspicuous heterogeneity of Cl- extrusion across laminae critically shapes plasticity for selective nociceptive modalities.
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Affiliation(s)
- Francesco Ferrini
- Department of Veterinary Sciences, University of Turin, Turin, Italy.
- CERVO Brain Research Centre, Québec, QC, Canada.
- Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada.
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada.
| | - Jimena Perez-Sanchez
- CERVO Brain Research Centre, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Samuel Ferland
- CERVO Brain Research Centre, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | | | - Antoine G Godin
- CERVO Brain Research Centre, Québec, QC, Canada
- Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Isabel Plasencia-Fernandez
- CERVO Brain Research Centre, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | | | | | - Feng Wang
- CERVO Brain Research Centre, Québec, QC, Canada
| | - Chiara Salio
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Nicolas Doyon
- CERVO Brain Research Centre, Québec, QC, Canada
- Department of Mathematics and Statistics, Université Laval, Québec, QC, Canada
| | - Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Yves De Koninck
- CERVO Brain Research Centre, Québec, QC, Canada
- Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
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21
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Wu X, Cai Q, Feng Z, Zhang M. Liquid-Liquid Phase Separation in Neuronal Development and Synaptic Signaling. Dev Cell 2020; 55:18-29. [PMID: 32726576 DOI: 10.1016/j.devcel.2020.06.012] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/27/2020] [Accepted: 06/09/2020] [Indexed: 01/09/2023]
Abstract
Formation of biomolecular condensates that are not enclosed by membranes via liquid-liquid phase separation (LLPS) is a general strategy that cells adopt to organize membraneless subcellular compartments for diverse functions. Neurons are highly polarized with elaborate branching and functional compartmentalization of their neurites, thus, raising additional demand for the proper subcellular localization of both membraneless and membrane-based organelles. Recent studies have provided evidence that several protein assemblies involved in the establishment of neuronal stem cell (NSC) polarity and in the asymmetric division of NSCs form distinct molecular condensates via LLPS. In synapses of adult neurons, molecular apparatuses controlling presynaptic neurotransmitter release and postsynaptic signaling transmission are also likely formed via LLPS. These molecular condensates, though not enclosed by lipid bilayers, directly associate with plasma membranes or membrane-based organelles, indicating that direct communication between membraneless and membrane-based organelles is a common theme in neurons and other types of cells.
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Affiliation(s)
- 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
| | - Qixu Cai
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - 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
| | - 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; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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22
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Lorenzo LE, Godin AG, Ferrini F, Bachand K, Plasencia-Fernandez I, Labrecque S, Girard AA, Boudreau D, Kianicka I, Gagnon M, Doyon N, Ribeiro-da-Silva A, De Koninck Y. Enhancing neuronal chloride extrusion rescues α2/α3 GABA A-mediated analgesia in neuropathic pain. Nat Commun 2020; 11:869. [PMID: 32054836 PMCID: PMC7018745 DOI: 10.1038/s41467-019-14154-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 12/16/2019] [Indexed: 02/06/2023] Open
Abstract
Spinal disinhibition has been hypothesized to underlie pain hypersensitivity in neuropathic pain. Apparently contradictory mechanisms have been reported, raising questions on the best target to produce analgesia. Here, we show that nerve injury is associated with a reduction in the number of inhibitory synapses in the spinal dorsal horn. Paradoxically, this is accompanied by a BDNF-TrkB-mediated upregulation of synaptic GABAARs and by an α1-to-α2GABAAR subunit switch, providing a mechanistic rationale for the analgesic action of the α2,3GABAAR benzodiazepine-site ligand L838,417 after nerve injury. Yet, we demonstrate that impaired Cl- extrusion underlies the failure of L838,417 to induce analgesia at high doses due to a resulting collapse in Cl- gradient, dramatically limiting the benzodiazepine therapeutic window. In turn, enhancing KCC2 activity not only potentiated L838,417-induced analgesia, it rescued its analgesic potential at high doses, revealing a novel strategy for analgesia in pathological pain, by combined targeting of the appropriate GABAAR-subtypes and restoring Cl- homeostasis.
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Affiliation(s)
- Louis-Etienne Lorenzo
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
| | - Antoine G Godin
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Francesco Ferrini
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
- Department of Veterinary Sciences, University of Turin, Turin, Italy
| | - Karine Bachand
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
| | - Isabel Plasencia-Fernandez
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Simon Labrecque
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
| | - Alexandre A Girard
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Ecole Polytechnique, IP Paris, Palaiseau, France
| | - Dominic Boudreau
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada
| | - Irenej Kianicka
- Chlorion Pharma, Laval, Québec, QC, Canada
- Laurent Pharmaceuticals Inc., Montreal, QC, Canada
| | - Martin Gagnon
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Centre for Innovation, University of Otago, Dunedin, New Zealand
| | - Nicolas Doyon
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada
- Finite Element Interdisciplinary Research Group (GIREF), Université Laval, Québec, QC, Canada
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada
- Department of Anatomy & Cell Biology, McGill University, Montreal, QC, Canada
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada
| | - Yves De Koninck
- CERVO Brain Research Centre, Quebec Mental Health Institute, Québec, QC, Canada.
- Department of Pharmacology & Therapeutics, McGill University, Montreal, QC, Canada.
- Department of Psychiatry & Neuroscience, Université Laval, Québec, QC, Canada.
- Graduate program in Neuroscience, Université Laval, Québec, QC, Canada.
- Alan Edwards Centre for Research on Pain, McGill University, Montreal, QC, Canada.
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23
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Garry J, Li Y, Shew B, Gradinaru CC, Rutenberg AD. Bayesian counting of photobleaching steps with physical priors. J Chem Phys 2020; 152:024110. [DOI: 10.1063/1.5132957] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Jon Garry
- Department of Physics & Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Yuchong Li
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Brandon Shew
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Claudiu C. Gradinaru
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Andrew D. Rutenberg
- Department of Physics & Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
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24
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Matsuda T, Oinuma I. Imaging endogenous synaptic proteins in primary neurons at single-cell resolution using CRISPR/Cas9. Mol Biol Cell 2019; 30:2838-2855. [PMID: 31509485 PMCID: PMC6789158 DOI: 10.1091/mbc.e19-04-0223] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Fluorescence imaging at single-cell resolution is a crucial approach to analyzing the spatiotemporal regulation of proteins within individual cells of complex neural networks. Here we present a nonviral strategy that enables the tagging of endogenous loci by CRISPR/Cas9-mediated genome editing combined with a nucleofection technique. The method allowed expression of fluorescently tagged proteins at endogenous levels, and we successfully achieved tagging of a presynaptic protein, synaptophysin (Syp), and a postsynaptic protein, PSD-95, in cultured postmitotic neurons. Superresolution fluorescence microscopy of fixed neurons confirmed the identical localization patterns of the tagged proteins to those of endogenous ones verified by immunohistochemistry. The system is also applicable for multiplexed labeling and live-cell imaging. Live imaging with total internal reflection fluorescence microscopy of a single dendritic process of a neuron double-labeled with Syp-mCherry and PSD-95-EGFP revealed the previously undescribed dynamic localization of the proteins synchronously moving along dendritic shafts. Our convenient and versatile strategy is potent for analysis of proteins whose ectopic expressions perturb cellular functions.
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Affiliation(s)
- Takahiko Matsuda
- Laboratory of Cell and Molecular Biology, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Izumi Oinuma
- Laboratory of Cell and Molecular Biology, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan.,Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto 606-8501, Japan
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25
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Zeng M, Díaz-Alonso J, Ye F, Chen X, Xu J, Ji Z, Nicoll RA, Zhang M. Phase Separation-Mediated TARP/MAGUK Complex Condensation and AMPA Receptor Synaptic Transmission. Neuron 2019; 104:529-543.e6. [PMID: 31492534 DOI: 10.1016/j.neuron.2019.08.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 06/02/2019] [Accepted: 07/29/2019] [Indexed: 12/22/2022]
Abstract
Transmembrane AMPA receptor (AMPAR) regulatory proteins (TARPs) modulate AMPAR synaptic trafficking and transmission via disc-large (DLG) subfamily of membrane-associated guanylate kinases (MAGUKs). Despite extensive studies, the molecular mechanism governing specific TARP/MAGUK interaction remains elusive. Using stargazin and PSD-95 as the representatives, we discover that the entire tail of stargazin (Stg_CT) is required for binding to PSD-95. The PDZ binding motif (PBM) and an Arg-rich motif upstream of PBM conserved in TARPs bind to multiple sites on PSD-95, thus resulting in a highly specific and multivalent stargazin/PSD-95 complex. Stargazin in complex with PSD-95 or PSD-95-assembled postsynaptic complexes form highly concentrated and dynamic condensates via phase separation, reminiscent of stargazin/PSD-95-mediated AMPAR synaptic clustering and trapping. Importantly, charge neutralization mutations in TARP_CT Arg-rich motif weakened TARP's condensation with PSD-95 and impaired TARP-mediated AMPAR synaptic transmission in mice hippocampal neurons. The TARP_CT/PSD-95 interaction mode may have implications for understanding clustering of other synaptic transmembrane proteins.
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Affiliation(s)
- Menglong Zeng
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Javier Díaz-Alonso
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Fei Ye
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xudong Chen
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jia Xu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Zeyang Ji
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Roger A Nicoll
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - 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; Center of Systems Biology and Human Health, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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26
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Yang X, Specht CG. Subsynaptic Domains in Super-Resolution Microscopy: The Treachery of Images. Front Mol Neurosci 2019; 12:161. [PMID: 31312120 PMCID: PMC6614521 DOI: 10.3389/fnmol.2019.00161] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 06/12/2019] [Indexed: 12/13/2022] Open
Abstract
The application of super-resolution optical microscopy to investigating synaptic structures has revealed a highly heterogeneous and variable intra-synaptic organization. Dense subsynaptic protein assemblies named subsynaptic domains or SSDs have been proposed as structural units that regulate the efficacy of neuronal transmission. However, an in-depth characterization of SSDs has been hampered by technical limitations of super-resolution microscopy of synapses, namely the stochasticity of the signals during the imaging procedures and the variability of the synaptic structures. Here, we synthetize the available evidence for the existence of SSDs at central synapses, as well as the possible functional relevance of SSDs. In particular, we discuss the possible regulation of co-transmission at mixed inhibitory synapses as a consequence of the subsynaptic distribution of glycine receptors (GlyRs) and GABAA receptors (GABAARs). LAY ABSTRACT Super-resolution imaging strategies bypass the resolution limit of conventional optical microscopy and have given new insights into the distribution of proteins at synapses in the central nervous system. Neurotransmitter receptors and scaffold proteins appear to occupy specialized locations within synapses that we refer to as subsynaptic domains or SSDs. Interestingly, these SSDs are highly dynamic and their formation seems to be related to the remodeling of synapses during synaptic plasticity. It was also shown that SSDs of pre-and post-synaptic proteins are aligned in so-called nanocolumns, highlighting the role of SSDs in the regulation of synaptic transmission. Despite recent advances, however, the detection of SSDs with super-resolution microscopy remains difficult due to the inherent technical limitations of these approaches that are discussed in this review article.
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Affiliation(s)
- Xiaojuan Yang
- École Normale Supérieure, PSL Research University, CNRS, Inserm, Institute of Biology (IBENS), Paris, France
| | - Christian G Specht
- École Normale Supérieure, PSL Research University, CNRS, Inserm, Institute of Biology (IBENS), Paris, France
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27
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Wilson RS, Rauniyar N, Sakaue F, Lam TT, Williams KR, Nairn AC. Development of Targeted Mass Spectrometry-Based Approaches for Quantitation of Proteins Enriched in the Postsynaptic Density (PSD). Proteomes 2019; 7:12. [PMID: 30986977 PMCID: PMC6630806 DOI: 10.3390/proteomes7020012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 03/27/2019] [Accepted: 03/28/2019] [Indexed: 02/07/2023] Open
Abstract
The postsynaptic density (PSD) is a structural, electron-dense region of excitatory glutamatergic synapses, which is involved in a variety of cellular and signaling processes in neurons. The PSD is comprised of a large network of proteins, many of which have been implicated in a wide variety of neuropsychiatric disorders. Biochemical fractionation combined with mass spectrometry analyses have enabled an in-depth understanding of the protein composition of the PSD. However, the PSD composition may change rapidly in response to stimuli, and robust and reproducible methods to thoroughly quantify changes in protein abundance are warranted. Here, we report on the development of two types of targeted mass spectrometry-based assays for quantitation of PSD-enriched proteins. In total, we quantified 50 PSD proteins in a targeted, parallel reaction monitoring (PRM) assay using heavy-labeled, synthetic internal peptide standards and identified and quantified over 2100 proteins through a pre-determined spectral library using a data-independent acquisition (DIA) approach in PSD fractions isolated from mouse cortical brain tissue.
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Affiliation(s)
- Rashaun S Wilson
- Yale/NIDA Neuroproteomics Center, New Haven, CT 06511, USA.
- W.M Keck Biotechnology Resource Laboratory, Yale University School of Medicine, New Haven, CT 06511, USA.
- Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06511, USA.
| | | | - Fumika Sakaue
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
- Department of Psychiatry, Yale School of Medicine, Connecticut Mental Health Center, New Haven, CT 06511, USA.
| | - TuKiet T Lam
- Yale/NIDA Neuroproteomics Center, New Haven, CT 06511, USA.
- W.M Keck Biotechnology Resource Laboratory, Yale University School of Medicine, New Haven, CT 06511, USA.
- Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06511, USA.
| | - Kenneth R Williams
- Yale/NIDA Neuroproteomics Center, New Haven, CT 06511, USA.
- Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06511, USA.
| | - Angus C Nairn
- Yale/NIDA Neuroproteomics Center, New Haven, CT 06511, USA.
- Department of Psychiatry, Yale School of Medicine, Connecticut Mental Health Center, New Haven, CT 06511, USA.
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28
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Gouder L, Vitrac A, Goubran-Botros H, Danckaert A, Tinevez JY, André-Leroux G, Atanasova E, Lemière N, Biton A, Leblond CS, Poulet A, Boland A, Deleuze JF, Benchoua A, Delorme R, Bourgeron T, Cloëz-Tayarani I. Altered spinogenesis in iPSC-derived cortical neurons from patients with autism carrying de novo SHANK3 mutations. Sci Rep 2019; 9:94. [PMID: 30643170 PMCID: PMC6331634 DOI: 10.1038/s41598-018-36993-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 11/28/2018] [Indexed: 01/19/2023] Open
Abstract
The synaptic protein SHANK3 encodes a multidomain scaffold protein expressed at the postsynaptic density of neuronal excitatory synapses. We previously identified de novo SHANK3 mutations in patients with autism spectrum disorders (ASD) and showed that SHANK3 represents one of the major genes for ASD. Here, we analyzed the pyramidal cortical neurons derived from induced pluripotent stem cells from four patients with ASD carrying SHANK3 de novo truncating mutations. At 40-45 days after the differentiation of neural stem cells, dendritic spines from pyramidal neurons presented variable morphologies: filopodia, thin, stubby and muschroom, as measured in 3D using GFP labeling and immunofluorescence. As compared to three controls, we observed a significant decrease in SHANK3 mRNA levels (less than 50% of controls) in correlation with a significant reduction in dendritic spine densities and whole spine and spine head volumes. These results, obtained through the analysis of de novo SHANK3 mutations in the patients' genomic background, provide further support for the presence of synaptic abnormalities in a subset of patients with ASD.
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Affiliation(s)
- Laura Gouder
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Aline Vitrac
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Hany Goubran-Botros
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | | | | | | | - Ekaterina Atanasova
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Nathalie Lemière
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Anne Biton
- Bioinformatics and Biostatistics Hub, C3BI, USR 3756 IP CNRS, Institut Pasteur, Paris, France
| | - Claire S Leblond
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | | | - Anne Boland
- Centre National de Recherche en Génomique Humaine (CNRGH), Institut de Biologie François Jacob, CEA, Université Paris-Saclay, F-91057, Evry, France
| | - Jean-François Deleuze
- Centre National de Recherche en Génomique Humaine (CNRGH), Institut de Biologie François Jacob, CEA, Université Paris-Saclay, F-91057, Evry, France
| | | | - Richard Delorme
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,Assistance Publique-Hôpitaux de Paris, Robert Debré Hospital, Department of Child and Adolescent Psychiatry, Paris, France
| | - Thomas Bourgeron
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France.,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Isabelle Cloëz-Tayarani
- Human Genetics and Cognitive Functions, Institut Pasteur, Paris, France. .,CNRS UMR 3571 « Genes, Synapses and Cognition », Institut Pasteur, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France.
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29
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Richter KN, Wildhagen H, Helm MS, Ußling JE, Schikorski T, Rizzoli SO. Comparative synaptosome imaging: a semi-quantitative method to obtain copy numbers for synaptic and neuronal proteins. Sci Rep 2018; 8:14838. [PMID: 30287847 PMCID: PMC6172260 DOI: 10.1038/s41598-018-33130-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/19/2018] [Indexed: 11/09/2022] Open
Abstract
Protein copy numbers can be measured by biochemical methods ranging from quantitative Western Blotting to several mass spectrometry approaches. Such methods only provide average copy numbers, obtained over large cell numbers. However, copy number estimates for single cells or single organelles could be obtained by combining biochemical characterizations with an imaging approach. We performed this here for synaptic proteins, in a protocol that we termed comparative synaptosome imaging for semi-quantitative copy numbers (CosiQuant). In brief, in CosiQuant we immunostain in parallel biochemically-characterized synaptosomes, for which we have already determined the average protein copy numbers, and the samples of interest (such as neuronal cultures). We then derive the copy numbers in the samples of interest by comparing the immunofluorescence intensities. We measured the intensities not only in arbitrary fluorescence units, but also as numbers of antibodies per synaptosome, for a large number of targets. This implies that other groups can immediately apply CosiQuant for these targets, by simply estimating the number of antibodies per structure of interest. CosiQuant should therefore be a useful addition to the growing set of imaging techniques for synaptic neuroscience.
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Affiliation(s)
- Katharina N Richter
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Humboldtallee 23, Göttingen, 37073, Germany. .,Cluster of Excellence Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany.
| | - Hanna Wildhagen
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Humboldtallee 23, Göttingen, 37073, Germany
| | - Martin S Helm
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Humboldtallee 23, Göttingen, 37073, Germany.,International Max Planck Research School Molecular Biology, Göttingen, Germany
| | - Jan-Eike Ußling
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Humboldtallee 23, Göttingen, 37073, Germany
| | - Thomas Schikorski
- Department of Neuroscience, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Silvio O Rizzoli
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Humboldtallee 23, Göttingen, 37073, Germany.
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30
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Leclerc S, Arntz Y, Taniguchi Y. Extending Single Molecule Imaging to Proteome Analysis by Quantitation of Fluorescent Labeling Homogeneity in Complex Protein Samples. Bioconjug Chem 2018; 29:2541-2549. [PMID: 29975043 DOI: 10.1021/acs.bioconjchem.8b00226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fluorescence-based electrophoresis has been widely used for proteome analysis in which every protein species in cells is labeled with a fluorescent dye, separated by electric migration, and quantified using fluorescence detection. The ultimate limit of sensitivity for this approach could be reached by single-molecule fluorescence imaging and counting individual proteins, requiring exhaustive fluorescent labeling of proteins across molecular populations and species. However, it remains unclear how homogeneous the fluorescence labeling of individual protein molecules of each species is across the proteome. To address this question, we developed a method to measure the labeling homogeneity based on a single-molecule fluorescence counting assay. Our results reveal that the proportion of proteins labeled with at least one dye, called labeling occupancy (LO), was 35% for fluorescently labeled BSA using existing protocols. We then found that the LO could be improved to 82% under high pH and surfactant-rich conditions. Furthermore, when a proteome sample from a human cell lysate was analyzed, the total LO was 71%, whereby the values varied between 50 and 90% for low and high molecular weight proteome fractions, respectively. The results support the possibility of sensitive detection of proteins using single-molecule counting with fluorescent labeling at the proteome scale.
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Affiliation(s)
- Simon Leclerc
- Laboratory for Cell Systems Control , RIKEN Center for Biosystems Dynamics Research , 6-2-3 Furuedai , Suita , Osaka 565-0874 , Japan.,Laboratoire de Biomatériaux et Bioimagerie , INSERM 1121 Université de Strasbourg, Faculté de Médecine , 4 rue Human , F-67000 Strasbourg , France
| | - Youri Arntz
- Laboratoire de Biomatériaux et Bioimagerie , INSERM 1121 Université de Strasbourg, Faculté de Médecine , 4 rue Human , F-67000 Strasbourg , France
| | - Yuichi Taniguchi
- Laboratory for Cell Systems Control , RIKEN Center for Biosystems Dynamics Research , 6-2-3 Furuedai , Suita , Osaka 565-0874 , Japan.,PRESTO, Japan Science and Technology Agency , 4-1-8 Honcho , Kawaguchi , Saitama 332-0012 , Japan
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31
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Reconstituted Postsynaptic Density as a Molecular Platform for Understanding Synapse Formation and Plasticity. Cell 2018; 174:1172-1187.e16. [PMID: 30078712 DOI: 10.1016/j.cell.2018.06.047] [Citation(s) in RCA: 243] [Impact Index Per Article: 40.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/17/2018] [Accepted: 06/26/2018] [Indexed: 11/21/2022]
Abstract
Synapses are semi-membraneless, protein-dense, sub-micron chemical reaction compartments responsible for signal processing in each and every neuron. Proper formation and dynamic responses to stimulations of synapses, both during development and in adult, are fundamental to functions of mammalian brains, although the molecular basis governing formation and modulation of compartmentalized synaptic assemblies is unclear. Here, we used a biochemical reconstitution approach to show that, both in solution and on supported membrane bilayers, multivalent interaction networks formed by major excitatory postsynaptic density (PSD) scaffold proteins led to formation of PSD-like assemblies via phase separation. The reconstituted PSD-like assemblies can cluster receptors, selectively concentrate enzymes, promote actin bundle formation, and expel inhibitory postsynaptic proteins. Additionally, the condensed phase PSD assemblies have features that are distinct from those in homogeneous solutions and fit for synaptic functions. Thus, we have built a molecular platform for understanding how neuronal synapses are formed and dynamically regulated.
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32
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Matt L, Kim K, Hergarden AC, Patriarchi T, Malik ZA, Park DK, Chowdhury D, Buonarati OR, Henderson PB, Gökçek Saraç Ç, Zhang Y, Mohapatra D, Horne MC, Ames JB, Hell JW. α-Actinin Anchors PSD-95 at Postsynaptic Sites. Neuron 2018; 97:1094-1109.e9. [PMID: 29429936 PMCID: PMC5963734 DOI: 10.1016/j.neuron.2018.01.036] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 12/10/2017] [Accepted: 01/17/2018] [Indexed: 12/17/2022]
Abstract
Despite the central role PSD-95 plays in anchoring postsynaptic AMPARs, how PSD-95 itself is tethered to postsynaptic sites is not well understood. Here we show that the F-actin binding protein α-actinin binds to the very N terminus of PSD-95. Knockdown (KD) of α-actinin phenocopies KD of PSD-95. Mutating lysine at position 10 or lysine at position 11 of PSD-95 to glutamate, or glutamate at position 53 or glutamate and aspartate at positions 213 and 217 of α-actinin, respectively, to lysine impairs, in parallel, PSD-95 binding to α-actinin and postsynaptic localization of PSD-95 and AMPARs. These experiments identify α-actinin as a critical PSD-95 anchor tethering the AMPAR-PSD-95 complex to postsynaptic sites.
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Affiliation(s)
- Lucas Matt
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Karam Kim
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Anne C Hergarden
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Tommaso Patriarchi
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Zulfiqar A Malik
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | - Deborah K Park
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | | | - Olivia R Buonarati
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Peter B Henderson
- Department of Pharmacology, University of California, Davis, Davis, CA, USA
| | - Çiğdem Gökçek Saraç
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Biomedical Engineering, Faculty of Engineering, Akdeniz University, Antalya, Turkey
| | - Yonghong Zhang
- Department of Chemistry, University of California, Davis, Davis, CA, USA
| | - Durga Mohapatra
- Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | - Mary C Horne
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Pharmacology, University of Iowa, Iowa City, IA, USA
| | - James B Ames
- Department of Chemistry, University of California, Davis, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California, Davis, Davis, CA, USA; Department of Pharmacology, University of Iowa, Iowa City, IA, USA.
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33
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de Las Heras-Martínez G, Andrieu J, Larijani B, Requejo-Isidro J. Quantifying intracellular equilibrium dissociation constants using single-channel time-resolved FRET. JOURNAL OF BIOPHOTONICS 2018; 11:e201600272. [PMID: 28485056 DOI: 10.1002/jbio.201600272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 02/20/2017] [Accepted: 02/23/2017] [Indexed: 06/07/2023]
Abstract
Quantification of the intracellular equilibrium dissociation constant of the interaction, Kd , is challenging due to the variability of the relative concentrations of the interacting proteins in the cell. Fluorescence lifetime imaging microscopy (FLIM) of the donor provides an accurate measurement of the molecular fraction of donor involved in FRET, but the fraction of bound acceptor is also needed to reliably estimate Kd . We present a method that exploits the spectroscopic properties of the widely used eGFP - mCherry FRET pair to rigorously determine the intracellular Kd based on imaging the fluorescence lifetime of only the donor (single-channel FLIM). We have assessed the effect of incomplete labelling and determined its range of application for different Kd using Monte Carlo simulations. We have demonstrated this method estimating the intracellular Kd for the homodimerisaton of the oncogenic protein 3-phosphoinositide-dependent kinase 1 (PDK1) in different cell lines and conditions, revealing a competitive mechanism for its regulation. The measured intracellular Kd was validated against in-vitro data. This method provides an accurate and generic tool to quantify protein interactions in situ.
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Affiliation(s)
| | - Josu Andrieu
- Instituto Biofisika (CSIC, UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain
| | - Banafshé Larijani
- Instituto Biofisika (CSIC, UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain
- Cell Biophysics Laboratory, Ikerbasque Basque Foundation for Science, Instituto Biofisika (CSIC, UPV/EHU) and Research Centre for Experimental Marine Biology and Biotechnology (PiE), University of the Basque Country (UPV/EHU), Leioa, 48940, Spain
| | - Jose Requejo-Isidro
- Instituto Biofisika (CSIC, UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain
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34
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Funk AJ, Mielnik CA, Koene R, Newburn E, Ramsey AJ, Lipska BK, McCullumsmith RE. Postsynaptic Density-95 Isoform Abnormalities in Schizophrenia. Schizophr Bull 2017; 43:891-899. [PMID: 28126896 PMCID: PMC5472126 DOI: 10.1093/schbul/sbw173] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Postsynaptic density-95 (PSD-95) protein expression is dysregulated in schizophrenia in a variety of brain regions. We have designed experiments to examine PSD-95 mRNA splice variant expression in the dorsolateral prefrontal cortex from subjects with schizophrenia. METHODS We performed quantitative PCR and western blot analysis to measure PSD-95 expression in schizophrenia vs control subjects, rodent haloperidol treatment studies, rodent postmortem interval studies, and GluN1 knockdown (KD) mice vs controls. RESULTS We found decreased mRNA expression of beta (t = 4.506, df = 383, P < .0001) and truncated (t = 3.378, df = 383, P = .0008) isoforms of PSD-95, whereas alpha was unchanged. Additionally, we found decreased PSD-95 protein expression in schizophrenia (t = 2.746, df = 71, P = .0076). We found no correlation between PSD-95 protein and alpha, beta, or truncated mRNA isoforms in schizophrenia. PSD-95 beta transcript was increased (t = 3.346, df = 14, P < .05) in the GluN1 KD mouse model of schizophrenia. There was an increase in PSD-95 alpha mRNA expression (t = 2.905, df = 16, P < .05) in rats following long-term haloperidol administration. CONCLUSIONS Our findings describe a unique pathophysiology of specific PSD-95 isoform dysregulation in schizophrenia, chronic neuroleptic treatment, and a genetic lesion mouse model of drastically reduced N-methyl-d-aspartate receptor (NMDAR) complex expression. These data indicate that regulation of PSD-95 is multifaceted, may be isoform specific, and biologically relevant for synaptic signaling function. Specifically, NMDAR-mediated synaptic remodeling, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor trafficking and interaction may be impaired in schizophrenia by decreased PSD-95 beta and truncated expression (respectively). Further, increased PSD-95 beta transcript in the GluN1 KD mouse model poses a potential compensatory rescue of NMDAR-mediated function via increased postsynaptic throughput of the severely reduced GluN1 signal. Together, these data propose that disruption of excitatory signaling complexes through genetic (GluN1 KD), pharmacologic (antipsychotics), or disease (schizophrenia) mechanisms specifically dysregulates PSD-95 expression.
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Affiliation(s)
- Adam J. Funk
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH
| | - Catharine A. Mielnik
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Rachael Koene
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH
| | | | - Amy J. Ramsey
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Barbara K. Lipska
- Human Brain Collection Core, Division of Intramural Research Programs, National Institute of Mental Health, National Institutes of Health, Bethesda, MD,Co-senior authors
| | - Robert E. McCullumsmith
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH;,Co-senior authors
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35
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Jung SR, Fujimoto BS, Chiu DT. Quantitative microscopy based on single-molecule fluorescence. Curr Opin Chem Biol 2017. [PMID: 28623730 DOI: 10.1016/j.cbpa.2017.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Quantitative microscopy is needed to understand reactions or phenomena carried out by biological molecules such as enzymes, receptors, and membrane-localized proteins. Counting the biomolecules of interest in single organelles or cellular compartments is critical in these approaches. In this brief perspective, we focus on the development of quantitative fluorescence microscopies that measure the precise copy numbers of proteins in cellular organelles or purified samples. We introduce recent improvements in quantitative microscopies to overcome undercounting or overcounting errors in certain conditions. We conclude by discussing biological applications.
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Affiliation(s)
- Seung-Ryoung Jung
- Department of Chemistry and Bioengineering, University of Washington, Seattle, WA 98195, United States
| | - Bryant S Fujimoto
- Department of Chemistry and Bioengineering, University of Washington, Seattle, WA 98195, United States
| | - Daniel T Chiu
- Department of Chemistry and Bioengineering, University of Washington, Seattle, WA 98195, United States.
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36
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Shah K, Rossie S. Tale of the Good and the Bad Cdk5: Remodeling of the Actin Cytoskeleton in the Brain. Mol Neurobiol 2017; 55:3426-3438. [PMID: 28502042 DOI: 10.1007/s12035-017-0525-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/06/2017] [Indexed: 11/24/2022]
Abstract
Cdk5 kinase, a cyclin-dependent kinase family member, is a key regulator of cytoskeletal remodeling in the brain. Cdk5 is essential for brain development during embryogenesis. After birth, it is essential for numerous neuronal processes such as learning and memory formation, drug addiction, pain signaling, and long-term behavior changes, all of which rely on rapid alterations in the cytoskeleton. Cdk5 activity is deregulated in various brain disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and ischemic stroke, resulting in profound remodeling of the neuronal cytoskeleton, loss of synapses, and ultimately neurodegeneration. This review focuses on the "good and bad" Cdk5 in the brain and its pleiotropic contribution in regulating neuronal actin cytoskeletal remodeling. A vast majority of physiological and pathological Cdk5 substrates are associated with the actin cytoskeleton. Thus, our special emphasis is on the numerous Cdk5 substrates identified in the past two decades such as ephexin1, p27, Mst3, CaMKv, kalirin-7, RasGRF2, Pak1, WAVE1, neurabin-1, TrkB, 5-HT6R, talin, drebrin, synapsin I, synapsin III, CRMP1, GKAP, SPAR, PSD-95, and LRRK2. These substrates have unraveled the molecular mechanisms by which Cdk5 plays divergent roles in regulating neuronal actin cytoskeletal dynamics both in healthy and diseased states.
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Affiliation(s)
- Kavita Shah
- Department of Chemistry and Purdue University Center of Cancer Research, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907, USA.
| | - Sandra Rossie
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
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37
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Patrizio A, Specht CG. Counting numbers of synaptic proteins: absolute quantification and single molecule imaging techniques. NEUROPHOTONICS 2016; 3:041805. [PMID: 27335891 PMCID: PMC4891561 DOI: 10.1117/1.nph.3.4.041805] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/02/2016] [Indexed: 06/06/2023]
Abstract
The ability to count molecules is essential to elucidating cellular mechanisms, as these often depend on the absolute numbers and concentrations of molecules within specific compartments. Such is the case at chemical synapses, where the transmission of information from presynaptic to postsynaptic terminals requires complex interactions between small sets of molecules. Be it the subunit stoichiometry specifying neurotransmitter receptor properties, the copy numbers of scaffold proteins setting the limit of receptor accumulation at synapses, or protein packing densities shaping the molecular organization and plasticity of the postsynaptic density, all of these depend on exact quantities of components. A variety of proteomic, electrophysiological, and quantitative imaging techniques have yielded insights into the molecular composition of synaptic complexes. In this review, we compare the different quantitative approaches and consider the potential of single molecule imaging techniques for the quantification of synaptic components. We also discuss specific neurobiological data to contextualize the obtained numbers and to explain how they aid our understanding of synaptic structure and function.
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Affiliation(s)
- Angela Patrizio
- Institute of Biology, Biologie Cellulaire de la Synapse, Inserm U1024, CNRS 8197, École Normale Supérieure (ENS), 46 rue d’Ulm, Paris 75005, France
| | - Christian G. Specht
- Institute of Biology, Biologie Cellulaire de la Synapse, Inserm U1024, CNRS 8197, École Normale Supérieure (ENS), 46 rue d’Ulm, Paris 75005, France
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38
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Walkup WG, Mastro TL, Schenker LT, Vielmetter J, Hu R, Iancu A, Reghunathan M, Bannon BD, Kennedy MB. A model for regulation by SynGAP-α1 of binding of synaptic proteins to PDZ-domain 'Slots' in the postsynaptic density. eLife 2016; 5. [PMID: 27623146 PMCID: PMC5040590 DOI: 10.7554/elife.16813] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 09/09/2016] [Indexed: 12/16/2022] Open
Abstract
SynGAP is a Ras/Rap GTPase-activating protein (GAP) that is a major constituent of postsynaptic densities (PSDs) from mammalian forebrain. Its α1 isoform binds to all three PDZ (PSD-95, Discs-large, ZO-1) domains of PSD-95, the principal PSD scaffold, and can occupy as many as 15% of these PDZ domains. We present evidence that synGAP-α1 regulates the composition of the PSD by restricting binding to the PDZ domains of PSD-95. We show that phosphorylation by Ca2+/calmodulin-dependent protein kinase II (CaMKII) and Polo-like kinase-2 (PLK2) decreases its affinity for the PDZ domains by several fold, which would free PDZ domains for occupancy by other proteins. Finally, we show that three critical postsynaptic signaling proteins that bind to the PDZ domains of PSD-95 are present in higher concentration in PSDs isolated from mice with a heterozygous deletion of synGAP.
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Affiliation(s)
- Ward G Walkup
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Tara L Mastro
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Leslie T Schenker
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Jost Vielmetter
- Beckman Institute Protein Expression Center, California Institute of Technology, Pasadena, United States
| | - Rebecca Hu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Ariella Iancu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Meera Reghunathan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Barry Dylan Bannon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Mary B Kennedy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
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Dosemeci A, Weinberg RJ, Reese TS, Tao-Cheng JH. The Postsynaptic Density: There Is More than Meets the Eye. Front Synaptic Neurosci 2016; 8:23. [PMID: 27594834 PMCID: PMC4990544 DOI: 10.3389/fnsyn.2016.00023] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 07/25/2016] [Indexed: 11/28/2022] Open
Abstract
The postsynaptic density (PSD), apparent in electron micrographs as a dense lamina just beneath the postsynaptic membrane, includes a deeper layer, the “pallium”, containing a scaffold of Shank and Homer proteins. Though poorly defined in traditionally prepared thin-section electron micrographs, the pallium becomes denser and more conspicuous during intense synaptic activity, due to the reversible addition of CaMKII and other proteins. In this Perspective article, we review the significance of CaMKII-mediated recruitment of proteins to the pallium with respect to both the trafficking of receptors and the remodeling of spine shape that follow synaptic stimulation. We suggest that the level and duration of CaMKII translocation and activation in the pallium will shape activity-induced changes in the spine.
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Affiliation(s)
- Ayse Dosemeci
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH) Bethesda, MD, USA
| | - Richard J Weinberg
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill Chapel Hill, NC, USA
| | - Thomas S Reese
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH) Bethesda, MD, USA
| | - Jung-Hwa Tao-Cheng
- Electron Microscopy Facility, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH) Bethesda, MD, USA
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40
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Dieterich DC, Kreutz MR. Proteomics of the Synapse--A Quantitative Approach to Neuronal Plasticity. Mol Cell Proteomics 2016; 15:368-81. [PMID: 26307175 PMCID: PMC4739661 DOI: 10.1074/mcp.r115.051482] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 07/29/2015] [Indexed: 11/06/2022] Open
Abstract
The advances in mass spectrometry based proteomics in the past 15 years have contributed to a deeper appreciation of protein networks and the composition of functional synaptic protein complexes. However, research on protein dynamics underlying core mechanisms of synaptic plasticity in brain lag far behind. In this review, we provide a synopsis on proteomic research addressing various aspects of synaptic function. We discuss the major topics in the study of protein dynamics of the chemical synapse and the limitations of current methodology. We highlight recent developments and the future importance of multidimensional proteomics and metabolic labeling. Finally, emphasis is given on the conceptual framework of modern proteomics and its current shortcomings in the quest to gain a deeper understanding of synaptic plasticity.
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Affiliation(s)
- Daniela C Dieterich
- From the ‡Institute for Pharmacology and Toxicology, Otto-von-Guericke University Magdeburg, Germany; Research Group Neuralomics, Leibniz Institute for Neurobiology Magdeburg, Germany; ¶Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
| | - Michael R Kreutz
- §RG Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; ¶Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
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41
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Harony-Nicolas H, De Rubeis S, Kolevzon A, Buxbaum JD. Phelan McDermid Syndrome: From Genetic Discoveries to Animal Models and Treatment. J Child Neurol 2015; 30:1861-70. [PMID: 26350728 PMCID: PMC5321557 DOI: 10.1177/0883073815600872] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 07/15/2015] [Indexed: 01/16/2023]
Abstract
Phelan-McDermid syndrome or 22q13.3 deletion syndrome is a rare neurodevelopmental disorder characterized by generalized developmental delay, intellectual disability, absent or delayed speech, seizures, autism spectrum disorder, neonatal hypotonia, physical dysmorphic features, and recurrent medical comorbidities. Individuals with Phelan-McDermid syndrome have terminal deletions of the chromosomal region 22q13.3 encompassing SHANK3, a gene encoding a structural component of excitatory synapses indispensable for proper synaptogenesis and neuronal physiology, or point mutations within the gene. Here, we review the clinical aspects of the syndrome and the genetic findings shedding light onto the underlying etiology. We also provide an overview on the evidence from genetic studies and mouse models that supports SHANK3 haploinsufficiency as a major contributor of the neurobehavioral manifestations of Phelan-McDermid syndrome. Finally, we discuss how all these discoveries are uncovering the pathophysiology of Phelan-McDermid syndrome and are being translated into clinical trials for novel therapeutics ameliorating the core symptoms of the disorder.
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Affiliation(s)
- Hala Harony-Nicolas
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Silvia De Rubeis
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Alexander Kolevzon
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Joseph D Buxbaum
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA The Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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42
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Lee-Montiel FT, Li P, Imoukhuede PI. Quantum dot multiplexing for the profiling of cellular receptors. NANOSCALE 2015; 7:18504-18514. [PMID: 26377627 DOI: 10.1039/c5nr01455g] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The profiling of cellular heterogeneity has wide-reaching importance for our understanding of how cells function and react to their environments in healthy and diseased states. Our ability to interpret and model cell behavior has been limited by the difficulties of measuring cell differences, for example, comparing tumor and non-tumor cells, particularly at the individual cell level. This demonstrates a clear need for a generalizable approach to profile fluorophore sites on cells or molecular assemblies on beads. Here, a multiplex immunoassay for simultaneous detection of five different angiogenic markers was developed. We targeted angiogenic receptors in the vascular endothelial growth factor family (VEGFR1, VEGFR2 and VEGFR3) and Neuropilin (NRP) family (NRP1 and NRP2), using multicolor quantum dots (Qdots). Copper-free click based chemistry was used to conjugate the monoclonal antibodies with 525, 565, 605, 655 and 705 nm CdSe/ZnS Qdots. We tested and performed colocalization analysis of our nanoprobes using the Pearson correlation coefficient statistical analysis. Human umbilical vein endothelial cells (HUVEC) were tested. The ability to easily monitor the molecular indicators of angiogenesis that are a precursor to cancer in a fast and cost effective system is an important step towards personalized nanomedicine.
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Affiliation(s)
- Felipe T Lee-Montiel
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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PSD-95 family MAGUKs are essential for anchoring AMPA and NMDA receptor complexes at the postsynaptic density. Proc Natl Acad Sci U S A 2015; 112:E6983-92. [PMID: 26604311 DOI: 10.1073/pnas.1517045112] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The postsynaptic density (PSD)-95 family of membrane-associated guanylate kinases (MAGUKs) are major scaffolding proteins at the PSD in glutamatergic excitatory synapses, where they maintain and modulate synaptic strength. How MAGUKs underlie synaptic strength at the molecular level is still not well understood. Here, we explore the structural and functional roles of MAGUKs at hippocampal excitatory synapses by simultaneous knocking down PSD-95, PSD-93, and synapse-associated protein (SAP)102 and combining electrophysiology and transmission electron microscopic (TEM) tomography imaging to analyze the resulting changes. Acute MAGUK knockdown greatly reduces synaptic transmission mediated by α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) and N-methyl-d-aspartate receptors (NMDARs). This knockdown leads to a significant rise in the number of silent synapses, diminishes the size of PSDs without changes in pre- or postsynaptic membrane, and depletes the number of membrane-associated PSD-95-like vertical filaments and transmembrane structures, identified as AMPARs and NMDARs by EM tomography. The differential distribution of these receptor-like structures and dependence of their abundance on PSD size matches that of AMPARs and NMDARs in the hippocampal synapses. The loss of these structures following MAGUK knockdown tracks the reduction in postsynaptic AMPAR and NMDAR transmission, confirming the structural identities of these two types of receptors. These results demonstrate that MAGUKs are required for anchoring both types of glutamate receptors at the PSD and are consistent with a structural model where MAGUKs, corresponding to membrane-associated vertical filaments, are the essential structural proteins that anchor and organize both types of glutamate receptors and govern the overall molecular organization of the PSD.
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Ultrastructural analyses in the hippocampus CA1 field in Shank3-deficient mice. Mol Autism 2015; 6:41. [PMID: 26137200 PMCID: PMC4486760 DOI: 10.1186/s13229-015-0036-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 06/22/2015] [Indexed: 11/10/2022] Open
Abstract
Background The genetics of autism spectrum disorder (hereafter referred to as “autism”) are rapidly unfolding, with a significant increase in the identification of genes implicated in the disorder. Many of these genes are part of a complex landscape of genetic variants that are thought to act together to cause the behavioral phenotype associated with autism. One of the few single-locus causes of autism involves a mutation in the SH3 and multiple ankyrin repeat domains 3 (SHANK3) gene. Previous electrophysiological studies in mice with Shank3 mutations demonstrated impairment in synaptic long-term potentiation, suggesting a potential disruption at the synapse. Methods To understand how variants in SHANK3 would lead to such impairments and manifest in the brain of patients with autism, we assessed the presence of synaptic pathology in Shank3-deficient mice at 5 weeks and 3 months of age, focusing on the stratum radiatum of the CA1 field. This study analyzed both Shank3 heterozygous and homozygous mice using an electron microscopy approach to determine whether there is a morphological correlate to the synaptic functional impairment. Results As both synaptic strength and plasticity are affected in Shank3-deficient mice, we hypothesized that there would be a reduction in synapse density, postsynaptic density length, and perforated synapse density. No differences were found in most parameters assessed. However, Shank3 heterozygotes had significantly higher numbers of perforated synapses at 5 weeks compared to 3 months of age and significantly higher numbers of perforated synapses compared to 5-week-old wildtype and Shank3 homozygous mice. Conclusions Although this finding represents preliminary evidence for ultrastructural alterations, it suggests that while major structural changes seem to be compensated for in Shank3-deficient mice, more subtle morphological alterations, affecting synaptic structure, may take place in an age-dependent manner.
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Merlo L, Cimino F, Angileri FF, La Torre D, Conti A, Cardali SM, Saija A, Germanò A. Alteration in synaptic junction proteins following traumatic brain injury. J Neurotrauma 2015; 31:1375-85. [PMID: 24661152 DOI: 10.1089/neu.2014.3385] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Extensive research and scientific efforts have been focused on the elucidation of the pathobiology of cellular and axonal damage following traumatic brain injury (TBI). Conversely, few studies have specifically addressed the issue of synaptic dysfunction. Synaptic junction proteins may be involved in post-TBI alterations, leading to synaptic loss or disrupted plasticity. A Synapse Protein Database on synapse ontology identified 109 domains implicated in synaptic activities and over 5000 proteins, but few of these demonstrated to play a role in the synaptic dysfunction after TBI. These proteins are involved in neuroplasticity and neuromodulation and, most importantly, may be used as novel neuronal markers of TBI for specific intervention.
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Affiliation(s)
- Lucia Merlo
- 1 Department of Neurosciences, University of Messina , Messina, Italy
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46
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Lowenthal MS, Markey SP, Dosemeci A. Quantitative mass spectrometry measurements reveal stoichiometry of principal postsynaptic density proteins. J Proteome Res 2015; 14:2528-38. [PMID: 25874902 DOI: 10.1021/acs.jproteome.5b00109] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Quantitative studies are presented of postsynaptic density (PSD) fractions from rat cerebral cortex with the ultimate goal of defining the average copy numbers of proteins in the PSD complex. Highly specific and selective isotope dilution mass spectrometry assays were developed using isotopically labeled polypeptide concatemer internal standards. Interpretation of PSD protein stoichiometry was achieved as a molar ratio with respect to PSD-95 (SAP-90, DLG4), and subsequently, copy numbers were estimated using a consensus literature value for PSD-95. Average copy numbers for several proteins at the PSD were estimated for the first time, including those for AIDA-1, BRAGs, and densin. Major findings include evidence for the high copy number of AIDA-1 in the PSD (144 ± 30)-equivalent to that of the total GKAP family of proteins (150 ± 27)-suggesting that AIDA-1 is an element of the PSD scaffold. The average copy numbers for NMDA receptor sub-units were estimated to be 66 ± 18, 27 ± 9, and 45 ± 15, respectively, for GluN1, GluN2A, and GluN2B, yielding a total of 34 ± 10 NMDA channels. Estimated average copy numbers for AMPA channels and their auxiliary sub-units TARPs were 68 ± 36 and 144 ± 38, respectively, with a stoichiometry of ∼1:2, supporting the assertion that most AMPA receptors anchor to the PSD via TARP sub-units. This robust, quantitative analysis of PSD proteins improves upon and extends the list of major PSD components with assigned average copy numbers in the ongoing effort to unravel the complex molecular architecture of the PSD.
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Affiliation(s)
- Mark S Lowenthal
- †Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Sanford P Markey
- †Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.,‡Laboratory of Neurotoxicology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Ayse Dosemeci
- §Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, United States
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Ratz M, Testa I, Hell SW, Jakobs S. CRISPR/Cas9-mediated endogenous protein tagging for RESOLFT super-resolution microscopy of living human cells. Sci Rep 2015; 5:9592. [PMID: 25892259 PMCID: PMC4402611 DOI: 10.1038/srep09592] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/12/2015] [Indexed: 12/20/2022] Open
Abstract
Overexpression is a notorious concern in conventional and especially in super-resolution fluorescence light microscopy studies because it may cause numerous artifacts including ectopic sub-cellular localizations, erroneous formation of protein complexes, and others. Nonetheless, current live cell super-resolution microscopy studies generally rely on the overexpression of a host protein fused to a fluorescent protein. Here, we establish CRISPR/Cas9-mediated generation of heterozygous and homozygous human knockin cell lines expressing fluorescently tagged proteins from their respective native genomic loci at close to endogenous levels. We tagged three different proteins, exhibiting various localizations and expression levels, with the reversibly switchable fluorescent protein rsEGFP2. We demonstrate the benefit of endogenous expression levels compared to overexpression and show that typical overexpression-induced artefacts were avoided in genome-edited cells. Fluorescence activated cell sorting analysis revealed a narrow distribution of fusion protein expression levels in genome-edited cells, compared to a pronounced variability in transiently transfected cells. Using low light intensity RESOLFT (reversible saturable optical fluorescence transitions) nanoscopy we show sub-diffraction resolution imaging of living human knockin cells. Our strategy to generate human cell lines expressing fluorescent fusion proteins at endogenous levels for RESOLFT nanoscopy can be extended to other fluorescent tags and super-resolution approaches.
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Affiliation(s)
- Michael Ratz
- Max Planck Institute for Biophysical Chemistry, Department of NanoBiophotonics, Am Fassberg 11, 37077 Göttingen, Germany
| | - Ilaria Testa
- Max Planck Institute for Biophysical Chemistry, Department of NanoBiophotonics, Am Fassberg 11, 37077 Göttingen, Germany
| | - Stefan W. Hell
- Max Planck Institute for Biophysical Chemistry, Department of NanoBiophotonics, Am Fassberg 11, 37077 Göttingen, Germany
| | - Stefan Jakobs
- Max Planck Institute for Biophysical Chemistry, Department of NanoBiophotonics, Am Fassberg 11, 37077 Göttingen, Germany
- University of Göttingen Medical Faculty, Dept. of Neurology, Robert-Koch-Str. 40, 37075 Göttingen, Germany
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Pagès S, Cane M, Randall J, Capello L, Holtmaat A. Single cell electroporation for longitudinal imaging of synaptic structure and function in the adult mouse neocortex in vivo. Front Neuroanat 2015; 9:36. [PMID: 25904849 PMCID: PMC4387926 DOI: 10.3389/fnana.2015.00036] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/09/2015] [Indexed: 11/13/2022] Open
Abstract
Longitudinal imaging studies of neuronal structures in vivo have revealed rich dynamics in dendritic spines and axonal boutons. Spines and boutons are considered to be proxies for synapses. This implies that synapses display similar dynamics. However, spines and boutons do not always bear synapses, some may contain more than one, and dendritic shaft synapses have no clear structural proxies. In addition, synaptic strength is not always accurately revealed by just the size of these structures. Structural and functional dynamics of synapses could be studied more reliably using fluorescent synaptic proteins as markers for size and function. These proteins are often large and possibly interfere with circuit development, which renders them less suitable for conventional transfection or transgenesis methods such as viral vectors, in utero electroporation, and germline transgenesis. Single cell electroporation (SCE) has been shown to be a potential alternative for transfection of recombinant fluorescent proteins in adult cortical neurons. Here we provide proof of principle for the use of SCE to express and subsequently image fluorescently tagged synaptic proteins over days to weeks in vivo.
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Affiliation(s)
- Stéphane Pagès
- Department of Basic Neurosciences and The Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva Geneva, Switzerland
| | - Michele Cane
- Department of Basic Neurosciences and The Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva Geneva, Switzerland
| | - Jérôme Randall
- Department of Basic Neurosciences and The Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva Geneva, Switzerland
| | - Luca Capello
- Itopie Informatique, Société Coopérative Geneva, Switzerland
| | - Anthony Holtmaat
- Department of Basic Neurosciences and The Center for Neuroscience, Centre Médical Universitaire (CMU), University of Geneva Geneva, Switzerland
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Abstract
Rapid and reversible methods for altering the function of endogenous proteins are not only indispensable tools for probing complex biological systems, but may potentially drive the development of new therapeutics for the treatment of human diseases. Genetic approaches have provided insights into protein function, but are limited in speed, reversibility and spatiotemporal control. To overcome these limitations, we have developed a peptide-based method (SNIPER: Selective Native Protein Eradication) to degrade any given endogenous protein at the post-translational level by harnessing chaperone-mediated autophagy, a major intracellular protein degradation pathway. This unit presents a typical strategy in the design and validation of a protein-knockdown peptide.
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Affiliation(s)
- Xuelai Fan
- Brain Research Centre and Department of Medicine, Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
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Taylor A, Steinberg J, Webber C. Duplications in ADHD patients harbour neurobehavioural genes that are co-expressed with genes associated with hyperactivity in the mouse. Am J Med Genet B Neuropsychiatr Genet 2015; 168B:97-107. [PMID: 25656289 PMCID: PMC4833176 DOI: 10.1002/ajmg.b.32285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 11/14/2014] [Indexed: 11/08/2022]
Abstract
Attention deficit/hyperactivity disorder (ADHD) is a childhood onset disorder, prevalent in 5.3% of children and 1-4% of adults. ADHD is highly heritable, with a burden of large (>500 Kb) copy number variants (CNVs) identified among individuals with ADHD. However, how such CNVs exert their effects is poorly understood. We examined the genes affected by 71 large, rare, and predominantly inherited CNVs identified among 902 individuals with ADHD. We applied both mouse-knockout functional enrichment analyses, exploiting behavioral phenotypes arising from the determined disruption of 1:1 mouse orthologues, and human brain-specific spatio-temporal expression data to uncover molecular pathways common among genes contributing to enriched phenotypes. Twenty-two percent of genes duplicated in individuals with ADHD that had mouse phenotypic information were associated with abnormal learning/memory/conditioning ("l/m/c") phenotypes. Although not observed in a second ADHD-cohort, we identified a similar enrichment among genes duplicated by eight de novo CNVs present in eight individuals with Hyperactivity and/or Short attention span ("Hyperactivity/SAS", the ontologically-derived phenotypic components of ADHD). In the brain, genes duplicated in patients with ADHD and Hyperactivity/SAS and whose orthologues' disruption yields l/m/c phenotypes in mouse ("candidate-genes"), were co-expressed with one another and with genes whose orthologues' mouse models exhibit hyperactivity. Moreover, genes associated with hyperactivity in the mouse were significantly more co-expressed with ADHD candidate-genes than with similarly identified genes from individuals with intellectual disability. Our findings support an etiology for ADHD distinct from intellectual disability, and mechanistically related to genes associated with hyperactivity phenotypes in other mammalian species.
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Affiliation(s)
- Avigail Taylor
- MRC Functional Genomics UnitDepartment of PhysiologyAnatomy and GeneticsUniversity of OxfordOxfordUnited Kingdom
| | - Julia Steinberg
- MRC Functional Genomics UnitDepartment of PhysiologyAnatomy and GeneticsUniversity of OxfordOxfordUnited Kingdom,The Wellcome Trust Centre for Human GeneticsUniversity of OxfordOxfordUnited Kingdom
| | - Caleb Webber
- MRC Functional Genomics UnitDepartment of PhysiologyAnatomy and GeneticsUniversity of OxfordOxfordUnited Kingdom
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