101
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Ciappelloni S, Bouchet D, Dubourdieu N, Boué-Grabot E, Kellermayer B, Manso C, Marignier R, Oliet SHR, Tourdias T, Groc L. Aquaporin-4 Surface Trafficking Regulates Astrocytic Process Motility and Synaptic Activity in Health and Autoimmune Disease. Cell Rep 2020; 27:3860-3872.e4. [PMID: 31242419 DOI: 10.1016/j.celrep.2019.05.097] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 03/08/2019] [Accepted: 05/23/2019] [Indexed: 01/21/2023] Open
Abstract
Astrocytes constantly adapt their ramified morphology in order to support brain cell assemblies. Such plasticity is partly mediated by ion and water fluxes, which rely on the water channel aquaporin-4 (AQP4). The mechanism by which this channel locally contributes to process dynamics has remained elusive. Using a combination of single-molecule and calcium imaging approaches, we here investigated in hippocampal astrocytes the dynamic distribution of the AQP4 isoforms M1 and M23. Surface AQP4-M1 formed small aggregates that contrast with the large AQP4-M23 clusters that are enriched near glutamatergic synapses. Strikingly, stabilizing surface AQP4-M23 tuned the motility of astrocyte processes and favors glutamate synapse activity. Furthermore, human autoantibodies directed against AQP4 from neuromyelitis optica (NMO) patients impaired AQP4-M23 dynamic distribution and, consequently, astrocyte process and synaptic activity. Collectively, it emerges that the membrane dynamics of AQP4 isoform regulate brain cell assemblies in health and autoimmune brain disease targeting AQP4.
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Affiliation(s)
- Silvia Ciappelloni
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Delphine Bouchet
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Nadège Dubourdieu
- Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Eric Boué-Grabot
- Université de Bordeaux, 33077 Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, 33000 Bordeaux, France
| | - Blanka Kellermayer
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Constance Manso
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France
| | - Romain Marignier
- INSERM U1028, CNRS UMR 5292, Center for Research in Neuroscience of Lyon, Lyon, France
| | - Stéphane H R Oliet
- Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Thomas Tourdias
- Université de Bordeaux, 33077 Bordeaux, France; INSERM U1215, Neurocentre Magendie, 33077 Bordeaux, France
| | - Laurent Groc
- Interdisciplinary Institute for NeuroSciences, CNRS UMR 5297, 33077 Bordeaux, France; Université de Bordeaux, 33077 Bordeaux, France.
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102
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Kokolaki ML, Fauquier A, Renner M. Molecular Crowding and Diffusion-Capture in Synapses. iScience 2020; 23:101382. [PMID: 32739837 PMCID: PMC7399191 DOI: 10.1016/j.isci.2020.101382] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/23/2020] [Accepted: 07/14/2020] [Indexed: 12/17/2022] Open
Abstract
Cell membranes often contain domains with important physiological functions. A typical example are neuronal synapses, whose capacity to capture receptors for neurotransmitters is central to neuronal functions. Receptors diffuse in the membrane until they are stabilized by interactions with stable elements, the scaffold. Single particle tracking experiments demonstrated that these interactions are rather weak and that lateral diffusion is strongly impaired in the post-synaptic membrane due to molecular crowding. We investigated how the distribution of scaffolding molecules and molecular crowding affect the capture of receptors. In particle-based Monte Carlo simulations, based on experimental data of molecular diffusion and organization, crowding enhanced the receptor-scaffold interaction but reduced the capture of new molecules. The distribution of scaffolding sites in several clusters reduced crowding and fostered the exchange of molecules accelerating synaptic plasticity. Synapses could switch between two regimes, becoming more stable or more plastic depending on the internal distribution of molecules. The good: molecular crowding enhances the interaction receptors-scaffold The bad: the exchange of molecules with extrasynaptic areas is reduced by crowding Molecular crowding helps synapses to be stable Nanoclusters of scaffold sites reduce crowding effects and favor synaptic plasticity
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Affiliation(s)
| | - Aurélien Fauquier
- Sorbonne Université UMR-S 1270 INSERM, Institut du Fer à Moulin (IFM), 75005 Paris, France
| | - Marianne Renner
- Sorbonne Université UMR-S 1270 INSERM, Institut du Fer à Moulin (IFM), 75005 Paris, France.
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103
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Pizzarelli R, Griguoli M, Zacchi P, Petrini EM, Barberis A, Cattaneo A, Cherubini E. Tuning GABAergic Inhibition: Gephyrin Molecular Organization and Functions. Neuroscience 2020; 439:125-136. [PMID: 31356900 PMCID: PMC7351109 DOI: 10.1016/j.neuroscience.2019.07.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/16/2019] [Accepted: 07/17/2019] [Indexed: 01/15/2023]
Abstract
To be highly reliable, synaptic transmission needs postsynaptic receptors (Rs) in precise apposition to the presynaptic release sites. At inhibitory synapses, the postsynaptic protein gephyrin self-assembles to form a scaffold that anchors glycine and GABAARs to the cytoskeleton, thus ensuring the accurate accumulation of postsynaptic receptors at the right place. This protein undergoes several post-translational modifications which control protein-protein interaction and downstream signaling pathways. In addition, through the constant exchange of scaffolding elements and receptors in and out of synapses, gephyrin dynamically regulates synaptic strength and plasticity. The aim of the present review is to highlight recent findings on the functional role of gephyrin at GABAergic inhibitory synapses. We will discuss different approaches used to interfere with gephyrin in order to unveil its function. In addition, we will focus on the impact of gephyrin structure and distribution at the nanoscale level on the functional properties of inhibitory synapses as well as the implications of this scaffold protein in synaptic plasticity processes. Finally, we will emphasize how gephyrin genetic mutations or alterations in protein expression levels are implicated in several neuropathological disorders, including autism spectrum disorders, schizophrenia, temporal lobe epilepsy and Alzheimer's disease, all associated with severe deficits of GABAergic signaling. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Rocco Pizzarelli
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy
| | - Marilena Griguoli
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy
| | - Paola Zacchi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Enrica Maria Petrini
- Fondazione Istituto Italiano di Tecnologia (IIT), Department of Neuroscience and Brain Technologies, Plasticity of inhibitory networks Unit, Genoa, Italy
| | - Andrea Barberis
- Fondazione Istituto Italiano di Tecnologia (IIT), Department of Neuroscience and Brain Technologies, Plasticity of inhibitory networks Unit, Genoa, Italy
| | - Antonino Cattaneo
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy; Scuola Normale Superiore, Pisa, Italy
| | - Enrico Cherubini
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy; Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy.
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104
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Nicholson L, Gervasi N, Falières T, Leroy A, Miremont D, Zala D, Hanus C. Whole-Cell Photobleaching Reveals Time-Dependent Compartmentalization of Soluble Proteins by the Axon Initial Segment. Front Cell Neurosci 2020; 14:180. [PMID: 32754013 PMCID: PMC7366827 DOI: 10.3389/fncel.2020.00180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/27/2020] [Indexed: 01/12/2023] Open
Abstract
By limiting protein exchange between the soma and the axon, the axon initial segment (AIS) enables the segregation of specific proteins and hence the differentiation of the somatodendritic compartment and the axonal compartment. Electron microscopy and super-resolution fluorescence imaging have provided important insights in the ultrastructure of the AIS. Yet, the full extent of its filtering properties is not fully delineated. In particular, it is unclear whether and how the AIS opposes the free exchange of soluble proteins. Here we describe a robust framework to combine whole-cell photobleaching and retrospective high-resolution imaging in developing neurons. With this assay, we found that cytoplasmic soluble proteins that are not excluded from the axon upon expression over tens of hours exhibit a strong mobility reduction at the AIS – i.e., are indeed compartmentalized – when monitored over tens of minutes. This form of compartmentalization is developmentally regulated, requires intact F-actin and may be correlated with the composition and ultrastructure of the submembranous spectrin cytoskeleton. Using computational modeling, we provide evidence that both neuronal morphology and the AIS regulate this compartmentalization but act on distinct time scales, with the AIS having a more pronounced effect on fast exchanges. Our results thus suggest that the rate of protein accumulation in the soma may impact to what extent and over which timescales freely moving molecules can be segregated from the axon. This in turn has important implications for our understanding of compartment-specific signaling in neurons.
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Affiliation(s)
- LaShae Nicholson
- Department of Neurology, Yale University School of Medicine, New Haven, CT, United States
| | - Nicolas Gervasi
- Center for Interdisciplinary Research in Biology, College de France, Inserm U1050, CNRS UMR 7241, Labex Memolife, Paris, France
| | - Thibault Falières
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Adrien Leroy
- Center for Interdisciplinary Research in Biology, College de France, Inserm U1050, CNRS UMR 7241, Labex Memolife, Paris, France
| | - Dorian Miremont
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Diana Zala
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
| | - Cyril Hanus
- Institute for Psychiatry and Neurosciences of Paris, Inserm UMR 1266, University of Paris, 4 GHU PARIS Psychiatrie & Neurosciences, Paris, France
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105
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Ahmad F, Liu P. Synaptosome as a tool in Alzheimer's disease research. Brain Res 2020; 1746:147009. [PMID: 32659233 DOI: 10.1016/j.brainres.2020.147009] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/21/2020] [Accepted: 07/04/2020] [Indexed: 12/29/2022]
Abstract
Synapse dysfunction is an integral feature of Alzheimer's disease (AD) pathophysiology. In fact, prodromal manifestation of structural and functional deficits in synapses much prior to appearance of overt pathological hallmarks of the disease indicates that AD might be considered as a degenerative disorder of the synapses. Several research instruments and techniques have allowed us to study synaptic function and plasticity and their alterations in pathological conditions, such as AD. One such tool is the biochemically isolated preparations of detached and resealed synaptic terminals, the "synaptosomes". Because of the preservation of many of the physiological processes such as metabolic and enzymatic activities, synaptosomes have proved to be an indispensable ex vivo model system to study synapse physiology both when isolated from fresh or cryopreserved tissues, and from animal or human post-mortem tissues. This model system has been tremendously successful in the case of post-mortem tissues because of their accessibility relative to acute brain slices or cultures. The current review details the use of synaptosomes in AD research and its potential as a valuable tool in furthering our understanding of the pathogenesis and in devising and testing of therapeutic strategies for the disease.
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Affiliation(s)
- Faraz Ahmad
- Department of Anatomy, School of Biomedical Sciences, Brain Research New Zealand, University of Otago, Dunedin, New Zealand.
| | - Ping Liu
- Department of Anatomy, School of Biomedical Sciences, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
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106
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Hisanaga SI, Wei R, Huo A, Tomomura M. LMTK1, a Novel Modulator of Endosomal Trafficking in Neurons. Front Mol Neurosci 2020; 13:112. [PMID: 32714146 PMCID: PMC7344150 DOI: 10.3389/fnmol.2020.00112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/02/2020] [Indexed: 12/16/2022] Open
Abstract
Neurons extend long processes known as axons and dendrites, through which they communicate with each other. The neuronal circuits formed by the axons and dendrites are the structural basis of higher brain functions. The formation and maintenance of these processes are essential for physiological brain activities. Membrane components, both lipids, and proteins, that are required for process formation are supplied by vesicle transport. Intracellular membrane trafficking is regulated by a family of Rab small GTPases. A group of Rabs regulating endosomal trafficking has been studied mainly in nonpolarized culture cell lines, and little is known about their regulation in polarized neurons with long processes. As shown in our recent study, lemur tail (former tyrosine) kinase 1 (LMTK1), an as yet uncharacterized Ser/Thr kinase associated with Rab11-positive recycling endosomes, modulates the formation of axons, dendrites, and spines in cultured primary neurons. LMTK1 knockdown or knockout (KO) or the expression of a kinase-negative mutant stimulates the transport of endosomal vesicles in neurons, leading to the overgrowth of axons, dendrites, and spines. More recently, we found that LMTK1 regulates TBC1D9B Rab11 GAP and proposed the Cdk5/p35-LMTK1-TBC1D9B-Rab11 pathway as a signaling cascade that regulates endosomal trafficking. Here, we summarize the biochemical, cell biological, and physiological properties of LMTK1.
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Affiliation(s)
- Shin-Ichi Hisanaga
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-Osawa Campus, Hachioji, Japan
| | - Ran Wei
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-Osawa Campus, Hachioji, Japan
| | - Anni Huo
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-Osawa Campus, Hachioji, Japan
| | - Mineko Tomomura
- Department of Oral Health Sciences, Meikai University School of Health Sciences, Urayasu, Japan
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107
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Lupascu CA, Morabito A, Ruggeri F, Parisi C, Pimpinella D, Pizzarelli R, Meli G, Marinelli S, Cherubini E, Cattaneo A, Migliore M. Computational Modeling of Inhibitory Transsynaptic Signaling in Hippocampal and Cortical Neurons Expressing Intrabodies Against Gephyrin. Front Cell Neurosci 2020; 14:173. [PMID: 32612513 PMCID: PMC7309579 DOI: 10.3389/fncel.2020.00173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/20/2020] [Indexed: 12/25/2022] Open
Abstract
GABAergic transmission regulates neuronal excitability, dendritic integration of synaptic signals and oscillatory activity, thought to be involved in high cognitive functions. By anchoring synaptic receptors just opposite to release sites, the scaffold protein gephyrin plays a key role in these tasks. In addition, by regulating GABAA receptor trafficking, gephyrin contributes to maintain, at the network level, an appropriate balance between Excitation (E) and Inhibition (I), crucial for information processing. An E/I imbalance leads to neuropsychiatric disorders such as epilepsy, schizophrenia and autism. In this article, we exploit a previously published computational method to fit spontaneous synaptic events, using a simplified model of the subcellular pathways involving gephyrin at inhibitory synapses. The model was used to analyze experimental data recorded under different conditions, with the main goal to gain insights on the possible consequences of gephyrin block on IPSCs. The same approach can be useful, in general, to analyze experiments designed to block a single protein. The results suggested possible ways to correlate the changes observed in the amplitude and time course of individual events recorded after different experimental protocols with the changes that may occur in the main subcellular pathways involved in gephyrin-dependent transsynaptic signaling.
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Affiliation(s)
- Carmen A Lupascu
- National Research Council, Institute of Biophysics, Palermo, Italy
| | | | | | | | | | | | | | | | | | | | - Michele Migliore
- National Research Council, Institute of Biophysics, Palermo, Italy
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108
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Rahmaninejad H, Pace T, Bhatt S, Sun B, Kekenes-Huskey P. Co-localization and confinement of ecto-nucleotidases modulate extracellular adenosine nucleotide distributions. PLoS Comput Biol 2020; 16:e1007903. [PMID: 32584811 PMCID: PMC7316229 DOI: 10.1371/journal.pcbi.1007903] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 04/22/2020] [Indexed: 12/30/2022] Open
Abstract
Nucleotides comprise small molecules that perform critical signaling roles in biological systems. Adenosine-based nucleotides, including adenosine tri-, di-, and mono-phosphate, are controlled through their rapid degradation by diphosphohydrolases and ecto-nucleotidases (NDAs). The interplay between nucleotide signaling and degradation is especially important in synapses formed between cells, which create signaling 'nanodomains'. Within these 'nanodomains', charged nucleotides interact with densely-packed membranes and biomolecules. While the contributions of electrostatic and steric interactions within such nanodomains are known to shape diffusion-limited reaction rates, less is understood about how these factors control the kinetics of nucleotidase activity. To quantify these factors, we utilized reaction-diffusion numerical simulations of 1) adenosine triphosphate (ATP) hydrolysis into adenosine monophosphate (AMP) and 2) AMP into adenosine (Ado) via two representative nucleotidases, CD39 and CD73. We evaluate these sequentially-coupled reactions in nanodomain geometries representative of extracellular synapses, within which we localize the nucleotidases. With this model, we find that 1) nucleotidase confinement reduces reaction rates relative to an open (bulk) system, 2) the rates of AMP and ADO formation are accelerated by restricting the diffusion of substrates away from the enzymes, and 3) nucleotidase co-localization and the presence of complementary (positive) charges to ATP enhance reaction rates, though the impact of these contributions on nucleotide pools depends on the degree to which the membrane competes for substrates. As a result, these contributions integratively control the relative concentrations and distributions of ATP and its metabolites within the junctional space. Altogether, our studies suggest that CD39 and CD73 nucleotidase activity within junctional spaces can exploit their confinement and favorable electrostatic interactions to finely control nucleotide signaling.
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Affiliation(s)
- Hadi Rahmaninejad
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Tom Pace
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky, United States of America
| | - Shashank Bhatt
- Paul Laurence Dunbar High School, Lexington, Kentucky, United States of America
| | - Bin Sun
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, United States of America
| | - Peter Kekenes-Huskey
- Department of Cell & Molecular Physiology, Loyola University Chicago, Chicago, Illinois, United States of America
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109
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Radler MR, Suber A, Spiliotis ET. Spatial control of membrane traffic in neuronal dendrites. Mol Cell Neurosci 2020; 105:103492. [PMID: 32294508 PMCID: PMC7317674 DOI: 10.1016/j.mcn.2020.103492] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/24/2020] [Accepted: 04/01/2020] [Indexed: 02/06/2023] Open
Abstract
Neuronal dendrites are highly branched and specialized compartments with distinct structures and secretory organelles (e.g., spines, Golgi outposts), and a unique cytoskeletal organization that includes microtubules of mixed polarity. Dendritic membranes are enriched with proteins, which specialize in the formation and function of the post-synaptic membrane of the neuronal synapse. How these proteins partition preferentially in dendrites, and how they traffic in a manner that is spatiotemporally accurate and regulated by synaptic activity are long-standing questions of neuronal cell biology. Recent studies have shed new insights into the spatial control of dendritic membrane traffic, revealing new classes of proteins (e.g., septins) and cytoskeleton-based mechanisms with dendrite-specific functions. Here, we review these advances by revisiting the fundamental mechanisms that control membrane traffic at the levels of protein sorting and motor-driven transport on microtubules and actin filaments. Overall, dendrites possess unique mechanisms for the spatial control of membrane traffic, which might have specialized and co-evolved with their highly arborized morphology.
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Affiliation(s)
- Megan R Radler
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA
| | - Ayana Suber
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, 3245 Chestnut St, Philadelphia, PA 19104, USA.
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110
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Bannai H, Niwa F, Sakuragi S, Mikoshiba K. Inhibitory synaptic transmission tuned by Ca 2+ and glutamate through the control of GABA A R lateral diffusion dynamics. Dev Growth Differ 2020; 62:398-406. [PMID: 32329058 PMCID: PMC7496684 DOI: 10.1111/dgd.12667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 04/08/2020] [Accepted: 04/18/2020] [Indexed: 11/30/2022]
Abstract
The GABAergic synapses, a primary inhibitory synapse in the mammalian brain, is important for the normal development of brain circuits, and for the regulation of the excitation‐inhibition balance critical for brain function from the developmental stage throughout life. However, the molecular mechanism underlying the formation, maintenance, and modulation of GABAergic synapses is less understood compared to that of excitatory synapses. Quantum dot‐single particle tracking (QD‐SPT), a super‐resolution imaging technique that enables the analysis of membrane molecule dynamics at single‐molecule resolution, is a powerful tool to analyze the behavior of proteins and lipids on the plasma membrane. In this review, we summarize the recent application of QD‐SPT in understanding of GABAergic synaptic transmission. Here we introduce QD‐SPT experiments that provide further insights into the molecular mechanism supporting GABAergic synapses. QD‐SPT studies revealed that glutamate and Ca2+ signaling is involved in (a) the maintenance of GABAergic synapses, (b) GABAergic long‐term depression, and GABAergic long‐term potentiation, by specifically activating signaling pathways unique to each phenomenon. We also introduce a novel Ca2+ imaging technique to describe the diversity of Ca2+ signals that may activate the downstream signaling pathways that induce specific biological output.
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Affiliation(s)
- Hiroko Bannai
- School of Advanced Science and Engineering, Department of Electrical Engineering and Biosciences, Waseda University, Tokyo, Japan.,Department of Neurophysiology, Keio University School of Medicine, Tokyo, Japan.,Japan Science and Technology Agency, PRESTO, Kawaguchi, Saitama, Japan.,Laboratory for Developmental Neurobiology, RIKEN Center for Brain Science, Wako, Japan
| | - Fumihiro Niwa
- Laboratory for Developmental Neurobiology, RIKEN Center for Brain Science, Wako, Japan.,Institut de Biologie de l'ENS (IBENS), École Normale Supérieure, PSL Research University, INSERM, CNRS, Paris, France
| | - Shigeo Sakuragi
- School of Advanced Science and Engineering, Department of Electrical Engineering and Biosciences, Waseda University, Tokyo, Japan.,Department of Pharmacology, Faculty of Medicine, Yamagata University, Yamagata, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Center for Brain Science, Wako, Japan.,Shanghai Institute for Advanced Immunochemical Studies (SIAIS), ShanghaiTech University, Shanghai, China.,Department of Biomolecular Science, Faculty of Science, Toho University, Funabashi, Japan
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111
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Nanostructural Diversity of Synapses in the Mammalian Spinal Cord. Sci Rep 2020; 10:8189. [PMID: 32424125 PMCID: PMC7235094 DOI: 10.1038/s41598-020-64874-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 04/21/2020] [Indexed: 11/25/2022] Open
Abstract
Functionally distinct synapses exhibit diverse and complex organisation at molecular and nanoscale levels. Synaptic diversity may be dependent on developmental stage, anatomical locus and the neural circuit within which synapses reside. Furthermore, astrocytes, which align with pre and post-synaptic structures to form ‘tripartite synapses’, can modulate neural circuits and impact on synaptic organisation. In this study, we aimed to determine which factors impact the diversity of excitatory synapses throughout the lumbar spinal cord. We used PSD95-eGFP mice, to visualise excitatory postsynaptic densities (PSDs) using high-resolution and super-resolution microscopy. We reveal a detailed and quantitative map of the features of excitatory synapses in the lumbar spinal cord, detailing synaptic diversity that is dependent on developmental stage, anatomical region and whether associated with VGLUT1 or VGLUT2 terminals. We report that PSDs are nanostructurally distinct between spinal laminae and across age groups. PSDs receiving VGLUT1 inputs also show enhanced nanostructural complexity compared with those receiving VGLUT2 inputs, suggesting pathway-specific diversity. Finally, we show that PSDs exhibit greater nanostructural complexity when part of tripartite synapses, and we provide evidence that astrocytic activation enhances PSD95 expression. Taken together, these results provide novel insights into the regulation and diversification of synapses across functionally distinct spinal regions and advance our general understanding of the ‘rules’ governing synaptic nanostructural organisation.
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112
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Huang L, Peng Z, Lu C, Chen Y, Lv JW, Qin M, Liao DF, Liu XM, Shi Z. Ginsenoside Rg1 alleviates repeated alcohol exposure-induced psychomotor and cognitive deficits. Chin Med 2020; 15:44. [PMID: 32411290 PMCID: PMC7206760 DOI: 10.1186/s13020-020-00325-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 04/28/2020] [Indexed: 12/25/2022] Open
Abstract
Background Chronic alcohol consumption disrupts psychomotor and cognitive functions, most of which are subserved by the dysfunction of hippocampus. Dysregulated excitatory glutamatergic transmission is implicated in repeated alcohol induced psychomotor and cognitive impairment. Ginsenoside Rg1, one of the main active ingredient of the traditional tonic medicine Panax ginseng C.A. Meyer (Araliaceae), has been used to treat cognitive deficits. Particularly, Rg1 has been demonstrated to improve hippocampus-dependent learning in mice and attenuate glutamate-induced excitotoxicity in vitro. Thus, in the present research, we sought to investigate the therapeutic effects of Ginsenoside Rg1 on repeated alcohol induced psychomotor and cognitive deficits in hippocampal-dependent behavioral tasks and unravel the underpinnings of its neuroprotection. Methods Male ICR (CD-1) mice were consecutively intragastrically treated with 20% (w/v) alcohol for 21 days. Then, behavior tests were conducted to evaluate repeated alcohol induced psychomotor and cognitive deficits. Histopathological changes, and biochemical and molecular alterations were assessed to determine the potential neuroprotective mechanism of Rg1. Results The results suggested that Rg1, at the optimal dose of 6 mg/kg, has the potential to ameliorate repeated alcohol induced cognitive deficits by regulating activities of NR2B containing NMDARs and excitotoxic signaling. Conclusion Our findings further provided a new strategy to treat chronic alcohol exposure induced adverse consequences.
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Affiliation(s)
- Lu Huang
- 1Division of Stem Cell Regulation and Application, Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, 410208 Hunan China.,2Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou, 510632 China
| | - Zhuang Peng
- 1Division of Stem Cell Regulation and Application, Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, 410208 Hunan China.,5College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029 China
| | - Cong Lu
- 3Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193 China
| | - Ying Chen
- 4Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700 China
| | - Jing-Wei Lv
- 3Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193 China
| | - Meng Qin
- 5College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, 100029 China
| | - Duan-Fang Liao
- 1Division of Stem Cell Regulation and Application, Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, 410208 Hunan China
| | - Xin-Min Liu
- 1Division of Stem Cell Regulation and Application, Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, 410208 Hunan China.,3Research Center for Pharmacology and Toxicology, Institute of Medicinal Plant Development (IMPLAD), Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100193 China
| | - Zhe Shi
- 1Division of Stem Cell Regulation and Application, Key Laboratory for Quality Evaluation of Bulk Herbs of Hunan Province, Hunan University of Chinese Medicine, Changsha, 410208 Hunan China
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113
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Abstract
Why did I choose this particular topic for my lecture rather than the history of neuroscience or the history of the neuron? Simply because I believe that every disciple has the obligation to pay homage to their mentors once in their lifetime. My formation as a neuroscientist involved three such mentors spanned across three countries. The first was Spain, where I was born, completed my medical studies, and had my first glimpse of neuroscience at the Cajal Institute with Fernando de Castro. It was him who, in 1961, advised me to spend some time abroad, and to that purpose he obtained me a scholarship from the French government, that allowed me to settle in Paris. Once in France I had the good fortune to meet Prof. René Couteaux, another generous mentor, who took care of my stay in the country. Two years later, he made me a proposition to which I could only answer in the affirmative by offering me a research position in France. I got married (the best thing that happened in my life), and spent the next 57 years working on the cerebellum. The third person I want to honor and remember in this presentation is Sanford Louis Palay who was my postdoc professor during the 2 years I worked at Harvard Medical School in Boston. And as it turns out, all three of my mentors have made positive contributions to the history of the synapse. So, without further delay, let us dive in. Anat Rec, 303:1252-1279, 2020. © 2020 American Association for Anatomy.
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Affiliation(s)
- Constantino Sotelo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Miguel Hernández (UMH), San Juan de Alicante, Spain
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114
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Siddig S, Aufmkolk S, Doose S, Jobin ML, Werner C, Sauer M, Calebiro D. Super-resolution imaging reveals the nanoscale organization of metabotropic glutamate receptors at presynaptic active zones. SCIENCE ADVANCES 2020; 6:eaay7193. [PMID: 32494600 PMCID: PMC7159906 DOI: 10.1126/sciadv.aay7193] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 01/22/2020] [Indexed: 05/12/2023]
Abstract
G protein-coupled receptors (GPCRs) play a fundamental role in the modulation of synaptic transmission. A pivotal example is provided by the metabotropic glutamate receptor type 4 (mGluR4), which inhibits glutamate release at presynaptic active zones (AZs). However, how GPCRs are organized within AZs to regulate neurotransmission remains largely unknown. Here, we applied two-color super-resolution imaging by direct stochastic optical reconstruction microscopy (dSTORM) to investigate the nanoscale organization of mGluR4 at parallel fiber AZs in the mouse cerebellum. We find an inhomogeneous distribution, with multiple nanodomains inside AZs, each containing, on average, one to two mGluR4 subunits. Within these nanodomains, mGluR4s are often localized in close proximity to voltage-dependent CaV2.1 channels and Munc-18-1, which are both essential for neurotransmitter release. These findings provide previously unknown insights into the molecular organization of GPCRs at AZs, suggesting a likely implication of a close association between mGluR4 and the secretory machinery in modulating synaptic transmission.
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Affiliation(s)
- Sana Siddig
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, Würzburg, Germany
- Department of Pharmacology, Faculty of Pharmacy, University of Khartoum, Khartoum, Sudan
| | - Sarah Aufmkolk
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Sören Doose
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Marie-Lise Jobin
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, Würzburg, Germany
| | - Christian Werner
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
- Corresponding author. (M.S.); (D.C.)
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, Würzburg, Germany
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Nottingham and Birmingham, Birmingham, UK
- Corresponding author. (M.S.); (D.C.)
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115
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Koch N, Koch D, Krueger S, Tröger J, Sabanov V, Ahmed T, McMillan LE, Wolf D, Montag D, Kessels MM, Balschun D, Qualmann B. Syndapin I Loss-of-Function in Mice Leads to Schizophrenia-Like Symptoms. Cereb Cortex 2020; 30:4306-4324. [DOI: 10.1093/cercor/bhaa013] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/10/2020] [Accepted: 01/14/2020] [Indexed: 12/12/2022] Open
Abstract
Abstract
Schizophrenia is associated with cognitive and behavioral dysfunctions thought to reflect imbalances in neurotransmission systems. Recent screenings suggested that lack of (functional) syndapin I (PACSIN1) may be linked to schizophrenia. We therefore studied syndapin I KO mice to address the suggested causal relationship to schizophrenia and to analyze associated molecular, cellular, and neurophysiological defects. Syndapin I knockout (KO) mice developed schizophrenia-related behaviors, such as hyperactivity, reduced anxiety, reduced response to social novelty, and an exaggerated novel object response and exhibited defects in dendritic arborization in the cortex. Neuromorphogenic deficits were also observed for a schizophrenia-associated syndapin I mutant in cultured neurons and coincided with a lack of syndapin I–mediated membrane recruitment of cytoskeletal effectors. Syndapin I KO furthermore caused glutamatergic hypofunctions. Syndapin I regulated both AMPAR and NMDAR availabilities at synapses during basal synaptic activity and during synaptic plasticity—particularly striking were a complete lack of long-term potentiation and defects in long-term depression in syndapin I KO mice. These synaptic plasticity defects coincided with alterations of postsynaptic actin dynamics, synaptic GluA1 clustering, and GluA1 mobility. Both GluA1 and GluA2 were not appropriately internalized. Summarized, syndapin I KO led to schizophrenia-like behavior, and our analyses uncovered associated molecular and cellular mechanisms.
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Affiliation(s)
- Nicole Koch
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Dennis Koch
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Sarah Krueger
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Jessica Tröger
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Victor Sabanov
- Laboratory of Biological Psychology, Brain & Cognition, University of Leuven, 3000 Leuven, Belgium
| | - Tariq Ahmed
- Laboratory of Biological Psychology, Brain & Cognition, University of Leuven, 3000 Leuven, Belgium
| | - Laura E McMillan
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
| | - David Wolf
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Dirk Montag
- Neurogenetics Lab, Leibniz Institute for Neurobiology, 39116 Magdeburg, Germany
| | - Michael M Kessels
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Detlef Balschun
- Laboratory of Biological Psychology, Brain & Cognition, University of Leuven, 3000 Leuven, Belgium
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, 07743 Jena, Germany
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116
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Bodakuntla S, Schnitzler A, Villablanca C, Gonzalez-Billault C, Bieche I, Janke C, Magiera MM. Tubulin polyglutamylation is a general traffic-control mechanism in hippocampal neurons. J Cell Sci 2020; 133:jcs241802. [PMID: 31932508 DOI: 10.1242/jcs.241802] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/23/2019] [Indexed: 08/31/2023] Open
Abstract
Neurons are highly complex cells that heavily rely on intracellular transport to distribute a range of functionally essential cargoes within the cell. Post-translational modifications of tubulin are emerging as mechanisms for regulating microtubule functions, but their impact on neuronal transport is only marginally understood. Here, we have systematically studied the impact of post-translational polyglutamylation on axonal transport. In cultured hippocampal neurons, deletion of a single deglutamylase, CCP1 (also known as AGTPBP1), is sufficient to induce abnormal accumulation of polyglutamylation, i.e. hyperglutamylation. We next investigated how hyperglutamylation affects axonal transport of a range of functionally different neuronal cargoes: mitochondria, lysosomes, LAMP1 endosomes and BDNF vesicles. Strikingly, we found a reduced motility for all these cargoes, suggesting that polyglutamylation could act as a regulator of cargo transport in neurons. This, together with the recent discovery that hyperglutamylation induces neurodegeneration, makes it likely that perturbed neuronal trafficking could be one of the central molecular causes underlying this novel type of degeneration.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Satish Bodakuntla
- Institut Curie, PSL Research University, CNRS UMR3348, F-91405 Orsay, France
- Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, F-91405 Orsay, France
| | - Anne Schnitzler
- Institut Curie, PSL Research University, Department of Genetics, F-75005 Paris, France
| | - Cristopher Villablanca
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago 7800003, Chile
- Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile
| | - Christian Gonzalez-Billault
- Center for Geroscience, Brain Health and Metabolism (GERO), Santiago 7800003, Chile
- Department of Biology, Faculty of Sciences, University of Chile, Santiago 7800003, Chile
| | - Ivan Bieche
- Institut Curie, PSL Research University, Department of Genetics, F-75005 Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, F-75005 Paris, France
| | - Carsten Janke
- Institut Curie, PSL Research University, CNRS UMR3348, F-91405 Orsay, France
- Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, F-91405 Orsay, France
| | - Maria M Magiera
- Institut Curie, PSL Research University, CNRS UMR3348, F-91405 Orsay, France
- Université Paris Sud, Université Paris-Saclay, CNRS UMR3348, F-91405 Orsay, France
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117
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Thal LB, Mann VR, Sprinzen D, McBride JR, Reid KR, Tomlinson ID, McMahon DG, Cohen BE, Rosenthal SJ. Ligand-conjugated quantum dots for fast sub-diffraction protein tracking in acute brain slices. Biomater Sci 2020; 8:837-845. [PMID: 31790090 PMCID: PMC7002256 DOI: 10.1039/c9bm01629e] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Semiconductor quantum dots (QDs) have demonstrated utility in long-term single particle tracking of membrane proteins in live cells in culture. To extend the superior optical properties of QDs to more physiologically relevant cell platforms, such as acute brain slices, we examine the photophysics of compact ligand-conjugated CdSe/CdS QDs using both ensemble and single particle analysis in brain tissue media. We find that symmetric core passivation is critical for both photostability in oxygenated media and for prolonged single particle imaging in brain slices. We then demonstrate the utility of these QDs by imaging single dopamine transporters in acute brain slices, achieving 20 nm localization precision at 10 Hz frame rates. These findings detail design requirements needed for new QD probes in complex living environments, and open the door to physiologically relevant studies that capture the utility of QD probes in acute brain slices.
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Affiliation(s)
- Lucas B Thal
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA.
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118
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Lv D, Yang Q, Chen Q, Chen J, Lai D, Chen H, Guo T. All-metal oxide synaptic transistor with modulatable plasticity. NANOTECHNOLOGY 2020; 31:065201. [PMID: 31645022 DOI: 10.1088/1361-6528/ab5080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The artificial neural system has attracted tremendous attention in the field of artificial intelligence due to operate mode of parallel computation which is superior to traditional Von Neumann computers in processing complex sensory data and real-time situations with extremely low power dissipation. Remarkable progress has been made in the hardware-based electric-double-layer synaptic transistors as its modulation by ion movement is similar to biological synapse for the past few years. Unfortunately, long-term potentiation (LTP) timescale is still a big challenge in hardware-based electric-double-layer synaptic transistors which is essential to processing capacity and memory formation. Meanwhile, the effect of ion concentration on the synaptic plasticity has rarely been reported. Here, a solid state electrolyte-gated transistor using Ta2O5 as dielectric layer with unique ionic composition was demonstrated and the regulation of synaptic weight was realized by changing ion concentration. Both the potentiation and depression of synaptic weight such as excitatory post-synaptic current, inhibitory response (IPSC), paired pulse facilitation as well as LTP were successfully simulated. More importantly, oxygen vacancy content was tuned for the first time to modulate synaptic plasticity by varying film thickness and gas ratio, through which the intensity and duration of memory were enhanced with appropriate vacancy concentration. It indicated that appropriate vacancy concentration avoided the effects of internal electric field induced by ion excess, leading to a long-term memory. These results reveal a promising path to improve memory capacity of artificial synapse via ion modulation.
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Affiliation(s)
- Dongxu Lv
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology, Fuzhou University, Fuzhou 350002, People's Republic of China
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119
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Dendritic Spines in Alzheimer's Disease: How the Actin Cytoskeleton Contributes to Synaptic Failure. Int J Mol Sci 2020; 21:ijms21030908. [PMID: 32019166 PMCID: PMC7036943 DOI: 10.3390/ijms21030908] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 01/24/2020] [Accepted: 01/26/2020] [Indexed: 02/06/2023] Open
Abstract
Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by Aβ-driven synaptic dysfunction in the early phases of pathogenesis. In the synaptic context, the actin cytoskeleton is a crucial element to maintain the dendritic spine architecture and to orchestrate the spine’s morphology remodeling driven by synaptic activity. Indeed, spine shape and synaptic strength are strictly correlated and precisely governed during plasticity phenomena in order to convert short-term alterations of synaptic strength into long-lasting changes that are embedded in stable structural modification. These functional and structural modifications are considered the biological basis of learning and memory processes. In this review we discussed the existing evidence regarding the role of the spine actin cytoskeleton in AD synaptic failure. We revised the physiological function of the actin cytoskeleton in the spine shaping and the contribution of actin dynamics in the endocytosis mechanism. The internalization process is implicated in different aspects of AD since it controls both glutamate receptor membrane levels and amyloid generation. The detailed understanding of the mechanisms controlling the actin cytoskeleton in a unique biological context as the dendritic spine could pave the way to the development of innovative synapse-tailored therapeutic interventions and to the identification of novel biomarkers to monitor synaptic loss in AD.
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120
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Shrivastava AN, Bousset L, Renner M, Redeker V, Savistchenko J, Triller A, Melki R. Differential Membrane Binding and Seeding of Distinct α-Synuclein Fibrillar Polymorphs. Biophys J 2020; 118:1301-1320. [PMID: 32059758 PMCID: PMC7091477 DOI: 10.1016/j.bpj.2020.01.022] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/18/2019] [Accepted: 01/15/2020] [Indexed: 02/08/2023] Open
Abstract
The aggregation of the protein α-synuclein (α-Syn) leads to different synucleinopathies. We recently showed that structurally distinct fibrillar α-Syn polymorphs trigger either Parkinson’s disease or multiple system atrophy hallmarks in vivo. Here, we establish a structural-molecular basis for these observations. We show that distinct fibrillar α-Syn polymorphs bind to and cluster differentially at the plasma membrane in both primary neuronal cultures and organotypic hippocampal slice cultures from wild-type mice. We demonstrate a polymorph-dependent and concentration-dependent seeding. We show a polymorph-dependent differential synaptic redistribution of α3-Na+/K+-ATPase, GluA2 subunit containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, and GluN2B-subunit containing N-methyl-D-aspartate receptors, but not GluA1 subunit containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and metabotropic glutamate receptor 5 receptors. We also demonstrate polymorph-dependent alteration in neuronal network activity upon seeded aggregation of α-Syn. Our findings bring new, to our knowledge, insight into how distinct α-Syn polymorphs differentially bind to and seed monomeric α-Syn aggregation within neurons, thus affecting neuronal homeostasis through the redistribution of synaptic proteins.
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Affiliation(s)
- Amulya Nidhi Shrivastava
- CEA, Institut François Jacob (MIRcen) and CNRS, Laboratory of Neurodegenerative Diseases, Fontenay-aux-Roses, France.
| | - Luc Bousset
- CEA, Institut François Jacob (MIRcen) and CNRS, Laboratory of Neurodegenerative Diseases, Fontenay-aux-Roses, France
| | - Marianne Renner
- INSERM, UMR- S 839 Institut du Fer à Moulin, Sorbonne Université, Paris, France
| | - Virginie Redeker
- CEA, Institut François Jacob (MIRcen) and CNRS, Laboratory of Neurodegenerative Diseases, Fontenay-aux-Roses, France
| | - Jimmy Savistchenko
- CEA, Institut François Jacob (MIRcen) and CNRS, Laboratory of Neurodegenerative Diseases, Fontenay-aux-Roses, France
| | - Antoine Triller
- École Normale Supérieure, Institut de Biologie de l'ENS, INSERM, CNRS, PSL, Research University, Paris, France.
| | - Ronald Melki
- CEA, Institut François Jacob (MIRcen) and CNRS, Laboratory of Neurodegenerative Diseases, Fontenay-aux-Roses, France.
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121
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Gralle M, Labrecque S, Salesse C, De Koninck P. Spatial dynamics of the insulin receptor in living neurons. J Neurochem 2020; 156:88-105. [PMID: 31886886 DOI: 10.1111/jnc.14950] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 12/11/2019] [Accepted: 12/27/2019] [Indexed: 12/23/2022]
Abstract
Insulin signaling through the insulin receptor has long been studied in classic target organs, such as adipose tissue and skeletal muscle, where one of its effects is to increase glucose uptake. Insulin and insulin receptor are present in many areas of the brain, but the functions of brain insulin signaling outside feeding circuits are not well defined. It has been proposed that hippocampal insulin signaling is important for memory, that brain insulin signaling is deficient in Alzheimer's disease, and that intranasal insulin treatment improves cognition, but the mechanisms remain unclear and do not seem to involve increased glucose uptake by neurons. The molecular behavior of the insulin receptor itself is not well known in living neurons; therefore, we investigated the spatial dynamics of the insulin receptor on somatodendritic membranes of live rat hippocampal neurons in culture. Using single-molecule tracking of quantum dot-tagged insulin receptors and single-particle tracking photoactivation localization microscopy, we show that the insulin receptor is distributed over both dendritic shafts and spines. Using colocalization with synaptic markers, we also show that in contrast to the glutamate receptor subunit glutamate receptor subunit A1, the dynamics of the insulin receptor are not affected by association with excitatory synapses; however, the insulin receptor is immobilized by components of inhibitory synapses. The mobility of the insulin receptor is reduced both by low concentrations of the pro-inflammatory cytokine tumor necrosis factor α and by cholesterol depletion, suggesting an association with sphingolipid-rich membrane domains. On the other hand, the insulin receptor dynamics in hippocampal neurons are not affected by increased excitatory signaling. Finally, using real-time single-event quantification, we find evidence of strong insulin receptor exocytosis on dendritic shafts. Our results suggest an association of the neuronal insulin receptor with specific elements of the dendritic shaft, rather than excitatory synapses.
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Affiliation(s)
- Matthias Gralle
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,CERVO Brain Research Center, Québec, QC, Canada
| | | | | | - Paul De Koninck
- CERVO Brain Research Center, Québec, QC, Canada.,Département de biochimie, microbiologie et bio-informatique, Université Laval, Québec, QC, Canada
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122
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TGF-β/Smad3 Signalling Modulates GABA Neurotransmission: Implications in Parkinson's Disease. Int J Mol Sci 2020; 21:ijms21020590. [PMID: 31963327 PMCID: PMC7013528 DOI: 10.3390/ijms21020590] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/13/2020] [Accepted: 01/14/2020] [Indexed: 12/12/2022] Open
Abstract
γ-Aminobutiryc acid (GABA) is found extensively in different brain nuclei, including parts involved in Parkinson’s disease (PD), such as the basal ganglia and hippocampus. In PD and in different models of the disorder, an increase in GABA neurotransmission is observed and may promote bradykinesia or L-Dopa-induced side-effects. In addition, proteins involved in GABAA receptor (GABAAR) trafficking, such as GABARAP, Trak1 or PAELR, may participate in the aetiology of the disease. TGF-β/Smad3 signalling has been associated with several pathological features of PD, such as dopaminergic neurodegeneration; reduction of dopaminergic axons and dendrites; and α-synuclein aggregation. Moreover, TGF-β/Smad3 intracellular signalling was recently shown to modulate GABA neurotransmission in the context of parkinsonism and cognitive alterations. This review provides a summary of GABA neurotransmission and TGF-β signalling; their implications in PD; and the regulation of GABA neurotransmission by TGF-β/Smad3. There appear to be new possibilities to develop therapeutic approaches for the treatment of PD using GABA modulators.
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123
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Hangen E, Cordelières FP, Petersen JD, Choquet D, Coussen F. Neuronal Activity and Intracellular Calcium Levels Regulate Intracellular Transport of Newly Synthesized AMPAR. Cell Rep 2020; 24:1001-1012.e3. [PMID: 30044968 PMCID: PMC6083039 DOI: 10.1016/j.celrep.2018.06.095] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 05/13/2018] [Accepted: 06/22/2018] [Indexed: 12/20/2022] Open
Abstract
Regulation of AMPA receptor (AMPAR) trafficking is a key modulator of excitatory synaptic transmission; however, intracellular vesicular transport of newly synthesized AMPARs has been little studied due to technical limitations. By combining molecular tools with imaging strategies in cultured rat hippocampal neurons, we found that vesicles containing newly synthesized, GluA1-subunit-containing AMPARs are transported antero- and retrogradely at a mean speed of 1.5 μm.s−1. Synaptic activity and variations in intracellular calcium levels bidirectionally modulate GluA1 transport. Chemical long-term potentiation (cLTP) initially induces a halt in GluA1 transport, followed by a sustained increase, while acute glutamate uncaging on synaptic spines arrests vesicular movements. GluA1 phosphomimetic mutants preferentially travel to the dendritic tip, probably to replenish extrasynaptic pools, distal to the soma. Our findings indicate that AMPAR intracellular transport is highly regulated during synaptic plasticity and likely controls AMPAR numbers at the plasma membrane. AMPARs are transported bidirectionally and intracellularly in dendrites ∼1.5 μm.s−1 Acute increase in intracellular Ca2+ during early LTP arrests GluA1-AMPAR vesicles 20 min after LTP induction, number and speed of GluA1-AMPAR vesicles are increased GluA1 phosphorylation at S831/S845 increases vesicle number and outward transport
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Affiliation(s)
- Emilie Hangen
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France
| | - Fabrice P Cordelières
- Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, Bordeaux, France
| | - Jennifer D Petersen
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, Bordeaux, France
| | - Daniel Choquet
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, Bordeaux, France
| | - Françoise Coussen
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France.
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124
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Maynard SA, Triller A. Inhibitory Receptor Diffusion Dynamics. Front Mol Neurosci 2019; 12:313. [PMID: 31920541 PMCID: PMC6930922 DOI: 10.3389/fnmol.2019.00313] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 12/04/2019] [Indexed: 11/13/2022] Open
Abstract
The dynamic modulation of receptor diffusion-trapping at inhibitory synapses is crucial to synaptic transmission, stability, and plasticity. In this review article, we will outline the progression of understanding of receptor diffusion dynamics at the plasma membrane. We will discuss how regulation of reversible trapping of receptor-scaffold interactions in combination with theoretical modeling approaches can be used to quantify these chemical interactions at the postsynapse of living cells.
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Affiliation(s)
- Stephanie A Maynard
- Institute of Biology of Ecole Normale Supérieure (IBENS), PSL Research University, CNRS, Inserm, Paris, France
| | - Antoine Triller
- Institute of Biology of Ecole Normale Supérieure (IBENS), PSL Research University, CNRS, Inserm, Paris, France
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125
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Fossati M, Assendorp N, Gemin O, Colasse S, Dingli F, Arras G, Loew D, Charrier C. Trans-Synaptic Signaling through the Glutamate Receptor Delta-1 Mediates Inhibitory Synapse Formation in Cortical Pyramidal Neurons. Neuron 2019; 104:1081-1094.e7. [PMID: 31704028 PMCID: PMC6926483 DOI: 10.1016/j.neuron.2019.09.027] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/11/2019] [Accepted: 09/17/2019] [Indexed: 12/14/2022]
Abstract
Fine orchestration of excitatory and inhibitory synaptic development is required for normal brain function, and alterations may cause neurodevelopmental disorders. Using sparse molecular manipulations in intact brain circuits, we show that the glutamate receptor delta-1 (GluD1), a member of ionotropic glutamate receptors (iGluRs), is a postsynaptic organizer of inhibitory synapses in cortical pyramidal neurons. GluD1 is selectively required for the formation of inhibitory synapses and regulates GABAergic synaptic transmission accordingly. At inhibitory synapses, GluD1 interacts with cerebellin-4, an extracellular scaffolding protein secreted by somatostatin-expressing interneurons, which bridges postsynaptic GluD1 and presynaptic neurexins. When binding to its agonist glycine or D-serine, GluD1 elicits non-ionotropic postsynaptic signaling involving the guanine nucleotide exchange factor ARHGEF12 and the regulatory subunit of protein phosphatase 1 PPP1R12A. Thus, GluD1 defines a trans-synaptic interaction regulating postsynaptic signaling pathways for the proper establishment of cortical inhibitory connectivity and challenges the dichotomy between iGluRs and inhibitory synaptic molecules.
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Affiliation(s)
- Matteo Fossati
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Nora Assendorp
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Olivier Gemin
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Sabrina Colasse
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France
| | - Florent Dingli
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, 75248 Paris Cedex 05, France
| | - Guillaume Arras
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, 75248 Paris Cedex 05, France
| | - Damarys Loew
- Institut Curie, PSL Research University, Centre de Recherche, Laboratoire de Spectrométrie de Masse Protéomique, 75248 Paris Cedex 05, France
| | - Cécile Charrier
- Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, 75005 Paris, France.
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126
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Chiu CQ, Barberis A, Higley MJ. Preserving the balance: diverse forms of long-term GABAergic synaptic plasticity. Nat Rev Neurosci 2019; 20:272-281. [PMID: 30837689 DOI: 10.1038/s41583-019-0141-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cellular mechanisms that regulate the interplay of synaptic excitation and inhibition are thought to be central to the functional stability of healthy neuronal circuits. A growing body of literature demonstrates the capacity for inhibitory GABAergic synapses to exhibit long-term plasticity in response to changes in neuronal activity. Here, we review this expanding field of research, focusing on the diversity of mechanisms that link glutamatergic signalling, postsynaptic action potentials and inhibitory synaptic strength. Several lines of evidence indicate that multiple, parallel forms of plasticity serve to regulate activity at both the input and output domains of individual neurons. Overall, these varied phenomena serve to promote both stability and flexibility over the life of the organism.
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Affiliation(s)
- Chiayu Q Chiu
- Centro Interdisciplinario de Neurociencia de Valparaiso, Universidad de Valparaiso, Valparaiso, Chile
| | | | - Michael J Higley
- Department of Neuroscience, Yale University, New Haven, CT, USA.
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127
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Morise J, Suzuki KGN, Kitagawa A, Wakazono Y, Takamiya K, Tsunoyama TA, Nemoto YL, Takematsu H, Kusumi A, Oka S. AMPA receptors in the synapse turnover by monomer diffusion. Nat Commun 2019; 10:5245. [PMID: 31748519 PMCID: PMC6868016 DOI: 10.1038/s41467-019-13229-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 10/28/2019] [Indexed: 12/27/2022] Open
Abstract
The number and subunit compositions of AMPA receptors (AMPARs), hetero- or homotetramers composed of four subunits GluA1–4, in the synapse is carefully tuned to sustain basic synaptic activity. This enables stimulation-induced synaptic plasticity, which is central to learning and memory. The AMPAR tetramers have been widely believed to be stable from their formation in the endoplasmic reticulum until their proteolytic decomposition. However, by observing GluA1 and GluA2 at the level of single molecules, we find that the homo- and heterotetramers are metastable, instantaneously falling apart into monomers, dimers, or trimers (in 100 and 200 ms, respectively), which readily form tetramers again. In the dendritic plasma membrane, GluA1 and GluA2 monomers and dimers are far more mobile than tetramers and enter and exit from the synaptic regions. We conclude that AMPAR turnover by lateral diffusion, essential for sustaining synaptic function, is largely done by monomers of AMPAR subunits, rather than preformed tetramers. The mechanisms regulating the turnover of the AMPARs in the synapse, which is critically important to sustain basic synaptic activity, remains unclear. In this study, authors used single-molecule imaging techniques to demonstrate that AMPAR tetramers are not stable entities and readily fall apart to dimers and monomers that could reform to tetramers at the synapse, and that rapidly diffusing monomers in the plasma membrane are primarily responsible for the AMPAR turnover in the synapse.
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Affiliation(s)
- Jyoji Morise
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Kenichi G N Suzuki
- Center for Highly Advanced Integration of Nano and Life Sciences (G-CHAIN), Gifu University, Gifu, 501-1193, Japan. .,Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan.
| | - Ayaka Kitagawa
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Yoshihiko Wakazono
- Department of Integrative Physiology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Kogo Takamiya
- Department of Integrative Physiology, Faculty of Medicine, University of Miyazaki, Miyazaki, 889-1692, Japan
| | - Taka A Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan
| | - Yuri L Nemoto
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan
| | - Hiromu Takematsu
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.,Department of Molecular Cell Biology, Faculty of Medical Technology, Graduate School of Health Sciences, Fujita Health University, Aichi, 470-1192, Japan
| | - Akihiro Kusumi
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 606-8507, Japan. .,Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Onna-son, Okinawa, 904-0495, Japan.
| | - Shogo Oka
- Department of Biological Chemistry, Division of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan.
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128
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The LMTK1-TBC1D9B-Rab11A Cascade Regulates Dendritic Spine Formation via Endosome Trafficking. J Neurosci 2019; 39:9491-9502. [PMID: 31628178 DOI: 10.1523/jneurosci.3209-18.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 10/04/2019] [Accepted: 10/10/2019] [Indexed: 12/30/2022] Open
Abstract
Dendritic spines are postsynaptic protrusions at excitatory synapses that are critical for proper neuronal synaptic transmission. While lipid and protein membrane components are necessary for spine formation, it is largely unknown how they are recruited to developing spines. Endosomal trafficking is one mechanism that may influence this development. We recently reported that Lemur kinase 1A (LMTK1A), a membrane-bound Ser/Thr kinase, regulates trafficking of endosomes in neurons. LMTK1 has been shown to be a p35 Cdk5 activator-binding protein and a substrate for Cdk5-p35; however, its neuronal function has not been sufficiently studied. Here, we investigate the role of LMTK1 in spine formation. Depletion of LMTK1 increases spine formation, maturation, and density in primary cultured neurons and in mouse brain of either sex. Additionally, expression of kinase-negative LMTK1 stimulates spine formation in primary neurons and in vivo LMTK1 controls spine formation through Rab11, a regulator of recycling endosome trafficking. We identify TBC1D9B, a Rab11A GTPase-activating protein (Rab11A GAP), as a LMTK1 binding protein, and find that TBC1D9B mediates LMTK1 activity on Rab11A. TBC1D9B inactivates Rab11A under the control of LMTK1A. Further, by analyzing the effect of decreased TBC1D9B expression in primary neurons, we demonstrate that TBC1D9B indeed regulates spine formation. This is the first demonstration of the biological function of TBC1D9B. Together, with the regulation of LMTK1 by Cdk5-p35, we propose the Cdk5-LMTK1-TBC1D9B-Rab11A cascade as a novel signaling mechanism regulating endosomal transport for synapse formation and function.SIGNIFICANCE STATEMENT Dendritic spines are postsynaptic specializations essential for synaptic transmission. However, it is not known how critical membrane components are recruited to spines for their formation. Endosomal trafficking is one such mechanism that may mediate this process. Here we investigate regulators of endosomal trafficking and their contribution to spine formation. We identify two novel factors, LMTK1 and TBC1D9B, which regulate spine formation upstream of Rab11A, a small GTPase. LMTK1 is a membrane bound Ser/Thr kinase regulated by Cdk5-p35, and TBC1D9B is a recently identified Rab11 GAP. LMTK1 controls the GAP activity of TBC1D9B on Rab11A, and TBC1D9B mediates the LMTK1 activity on Rab11A. We propose the Cdk5-LMTK1-TBC1D9B-Rab11A cascade as a novel mechanism controlling spine formation and function.
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129
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Linking Nanoscale Dynamics of AMPA Receptor Organization to Plasticity of Excitatory Synapses and Learning. J Neurosci 2019; 38:9318-9329. [PMID: 30381423 DOI: 10.1523/jneurosci.2119-18.2018] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 09/21/2018] [Accepted: 09/21/2018] [Indexed: 11/21/2022] Open
Abstract
The spatiotemporal organization of neurotransmitter receptors in the postsynaptic membrane is a fundamental determinant of synaptic transmission and thus of information processing by the brain. The ionotropic AMPA subtype of glutamate receptors (AMPARs) mediate fast excitatory synaptic transmission in the CNS. The number of AMPARs located en face presynaptic glutamate release sites sets the efficacy of synaptic transmission. Understanding how this number is set and regulated has been the topic of intense research in the last two decades. We showed that AMPARs are not stable in the synapse as initially thought. They continuously enter and exit the postsynaptic density by lateral diffusion, and they exchange between the neuronal surface and intracellular compartments by endocytosis and exocytosis at extrasynaptic sites. Regulation of these various trafficking pathways has emerged as a key mechanism for activity-dependent plasticity of synaptic transmission, a process important for learning and memory. I here present my view of these findings. In particular, the advent of super-resolution microscopy and single-molecule tracking has helped to uncover the intricacy of AMPARs' dynamic organization at the nanoscale. In addition, AMPAR surface diffusion is highly regulated by a variety of factors, including neuronal activity, stress hormones, and neurodegeneration, suggesting that AMPAR diffusion-trapping may play a central role in synapse function. Using innovative tools to understand further the link between receptor dynamics and synapse plasticity is now unveiling new molecular mechanisms of learning. Modifying AMPAR dynamics may emerge as a new target to correct synapse dysfunction in the diseased brain.
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130
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Phosphorylation of Gephyrin in Zebrafish Mauthner Cells Governs Glycine Receptor Clustering and Behavioral Desensitization to Sound. J Neurosci 2019; 39:8988-8997. [PMID: 31558619 DOI: 10.1523/jneurosci.1315-19.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 09/16/2019] [Accepted: 09/20/2019] [Indexed: 01/01/2023] Open
Abstract
The process by which future behavioral responses are shaped by past experiences is one of the central questions in neuroscience. To gain insight into this process at the molecular and cellular levels, we have applied zebrafish larvae to explore behavioral desensitization to sound. A sudden loud noise often evokes a defensive response known as the acoustic startle response (ASR), which is triggered by firing Mauthner cells in teleosts and amphibians. The probability of evoking ASR by suprathreshold sound is reduced after exposure to repetitive auditory stimuli insufficient in amplitude to evoke the ASR (subthreshold). Although it has been suggested that the potentiation of inhibitory glycinergic inputs into Mauthner cell is involved in this desensitization of the ASR, the molecular basis for the potentiation of glycinergic transmission has been unclear. Through the in vivo monitoring of fluorescently-tagged glycine receptors (GlyRs), we here showed that behavioral desensitization to sound in zebrafish is governed by GlyR clustering in Mauthner cells. We further revealed that CaMKII-dependent phosphorylation of the scaffolding protein gephyrin at serine 325 promoted the synaptic accumulation of GlyR on Mauthner neurons through the enhancement of the gephyrin-GlyR binding, which was indispensable for and could induce desensitization of the ASR. Our study demonstrates an essential molecular and cellular basis of sound-induced receptor dynamics and thus of behavioral desensitization to sound.SIGNIFICANCE STATEMENT Behavioral desensitization in the acoustic startle response of fish is known to involve the potentiation of inhibitory glycinergic input to the Mauthner cell, which is a command neuron for the acoustic startle response. However, the molecular and cellular basis for this potentiation has been unknown. Here we show that an increase in glycine receptor (GlyR) clustering at synaptic sites on zebrafish Mauthner cells is indispensable for and could induce desensitization. Furthermore, we demonstrate that CaMKII-mediated phosphorylation of the scaffolding protein gephyrin promotes GlyR clustering by increasing the binding between the β-loop of GlyRs and gephyrin. Thus, the phosphorylation of gephyrin is a key event which accounts for the potentiation of inhibitory glycinergic inputs observed during sound-evoked behavioral desensitization.
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131
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Humeau Y, Choquet D. The next generation of approaches to investigate the link between synaptic plasticity and learning. Nat Neurosci 2019; 22:1536-1543. [PMID: 31477899 DOI: 10.1038/s41593-019-0480-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/26/2019] [Indexed: 12/28/2022]
Abstract
Activity-dependent synaptic plasticity has since long been proposed to represent the subcellular substrate of learning and memory, one of the most important behavioral processes through which we adapt to our environment. Despite the undisputed importance of synaptic plasticity for brain function, its exact contribution to learning processes in the context of cellular and connectivity modifications remains obscure. Causally bridging synaptic and behavioral modifications indeed remains limited by the available tools to measure and control synaptic strength and plasticity in vivo under behaviorally relevant conditions. After a brief summary of the current state of knowledge of the links between synaptic plasticity and learning, we will review and discuss the available and desired tools to progress in this endeavor.
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Affiliation(s)
- Yann Humeau
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, Bordeaux, France. .,Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, Bordeaux, France.
| | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, Bordeaux, France. .,Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, Bordeaux, France. .,Bordeaux Imaging Center, UMS 3420 CNRS - University of Bordeaux, US4 INSERM, Bordeaux, France.
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132
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Kulik YD, Watson DJ, Cao G, Kuwajima M, Harris KM. Structural plasticity of dendritic secretory compartments during LTP-induced synaptogenesis. eLife 2019; 8:e46356. [PMID: 31433297 PMCID: PMC6728136 DOI: 10.7554/elife.46356] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 08/20/2019] [Indexed: 12/30/2022] Open
Abstract
Long-term potentiation (LTP), an increase in synaptic efficacy following high-frequency stimulation, is widely considered a mechanism of learning. LTP involves local remodeling of dendritic spines and synapses. Smooth endoplasmic reticulum (SER) and endosomal compartments could provide local stores of membrane and proteins, bypassing the distant Golgi apparatus. To test this hypothesis, effects of LTP were compared to control stimulation in rat hippocampal area CA1 at postnatal day 15 (P15). By two hours, small spines lacking SER increased after LTP, whereas large spines did not change in frequency, size, or SER content. Total SER volume decreased after LTP consistent with transfer of membrane to the added spines. Shaft SER remained more abundant in spiny than aspiny dendritic regions, apparently supporting the added spines. Recycling endosomes were elevated specifically in small spines after LTP. These findings suggest local secretory trafficking contributes to LTP-induced synaptogenesis and primes the new spines for future plasticity.
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Affiliation(s)
- Yelena D Kulik
- Center for Learning and Memory, Department of NeuroscienceThe University of Texas at AustinAustinUnited States
| | - Deborah J Watson
- Center for Learning and Memory, Department of NeuroscienceThe University of Texas at AustinAustinUnited States
| | - Guan Cao
- Center for Learning and Memory, Department of NeuroscienceThe University of Texas at AustinAustinUnited States
| | - Masaaki Kuwajima
- Center for Learning and Memory, Department of NeuroscienceThe University of Texas at AustinAustinUnited States
| | - Kristen M Harris
- Center for Learning and Memory, Department of NeuroscienceThe University of Texas at AustinAustinUnited States
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133
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Two-dimensional materials for synaptic electronics and neuromorphic systems. Sci Bull (Beijing) 2019; 64:1056-1066. [PMID: 36659765 DOI: 10.1016/j.scib.2019.01.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/02/2019] [Accepted: 01/11/2019] [Indexed: 01/21/2023]
Abstract
Synapses in biology provide a variety of functions for the neural system. Artificial synaptic electronics that mimic the biological neuron functions are basic building blocks and developing novel artificial synapses is essential for neuromorphic computation. Inspired by the unique features of biological synapses that the basic connection components of the nervous system and the parallelism, low power consumption, fault tolerance, self-learning and robustness of biological neural systems, artificial synaptic electronics and neuromorphic systems have the potential to overcome the traditional von Neumann bottleneck and create a new paradigm for dealing with complex problems such as pattern recognition, image classification, decision making and associative learning. Nowadays, two-dimensional (2D) materials have drawn great attention in simulating synaptic dynamic plasticity and neuromorphic computing with their unique properties. Here we describe the basic concepts of bio-synaptic plasticity and learning, the 2D materials library and its preparation. We review recent advances in synaptic electronics and artificial neuromorphic systems based on 2D materials and provide our perspective in utilizing 2D materials to implement synaptic electronics and neuromorphic systems in hardware.
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134
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Trotter JH, Hao J, Maxeiner S, Tsetsenis T, Liu Z, Zhuang X, Südhof TC. Synaptic neurexin-1 assembles into dynamically regulated active zone nanoclusters. J Cell Biol 2019; 218:2677-2698. [PMID: 31262725 PMCID: PMC6683742 DOI: 10.1083/jcb.201812076] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 05/10/2019] [Accepted: 05/30/2019] [Indexed: 12/04/2022] Open
Abstract
Neurexins are well-characterized presynaptic cell adhesion molecules that engage multifarious postsynaptic ligands and organize diverse synapse properties. However, the precise synaptic localization of neurexins remains enigmatic. Using super-resolution microscopy, we demonstrate that neurexin-1 forms discrete nanoclusters at excitatory synapses, revealing a novel organizational feature of synaptic architecture. Synapses generally contain a single nanocluster that comprises more than four neurexin-1 molecules and that also includes neurexin-2 and/or neurexin-3 isoforms. Moreover, we find that neurexin-1 is physiologically cleaved by ADAM10 similar to its ligand neuroligin-1, with ∼4-6% of neurexin-1 and ∼2-3% of neuroligin-1 present in the adult brain as soluble ectodomain proteins. Blocking ADAM10-mediated neurexin-1 cleavage dramatically increased the synaptic neurexin-1 content, thereby elevating the percentage of Homer1(+) excitatory synapses containing neurexin-1 nanoclusters from 40-50% to ∼80%, and doubling the number of neurexin-1 molecules per nanocluster. Taken together, our results reveal an unexpected nanodomain organization of synapses in which neurexin-1 is assembled into discrete presynaptic nanoclusters that are dynamically regulated via ectodomain cleavage.
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Affiliation(s)
- Justin H Trotter
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Junjie Hao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA
- Department of Physics, Harvard University, Cambridge, MA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA
| | - Stephan Maxeiner
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Theodoros Tsetsenis
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Zhihui Liu
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
| | - Xiaowei Zhuang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA
- Department of Physics, Harvard University, Cambridge, MA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA
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135
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Karbowski J. Metabolic constraints on synaptic learning and memory. J Neurophysiol 2019; 122:1473-1490. [PMID: 31365284 DOI: 10.1152/jn.00092.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dendritic spines, the carriers of long-term memory, occupy a small fraction of cortical space, and yet they are the major consumers of brain metabolic energy. What fraction of this energy goes for synaptic plasticity, correlated with learning and memory? It is estimated here based on neurophysiological and proteomic data for rat brain that, depending on the level of protein phosphorylation, the energy cost of synaptic plasticity constitutes a small fraction of the energy used for fast excitatory synaptic transmission, typically 4.0-11.2%. Next, this study analyzes a metabolic cost of new learning and its memory trace in relation to the cost of prior memories, using a class of cascade models of synaptic plasticity. It is argued that these models must contain bidirectional cyclic motifs, related to protein phosphorylation, to be compatible with basic thermodynamic principles. For most investigated parameters longer memories generally require proportionally more energy to store. The exceptions are the parameters controlling the speed of molecular transitions (e.g., ATP-driven phosphorylation rate), for which memory lifetime per invested energy can increase progressively for longer memories. Furthermore, in general, a memory trace decouples dynamically from a corresponding synaptic metabolic rate such that the energy expended on new learning and its memory trace constitutes in most cases only a small fraction of the baseline energy associated with prior memories. Taken together, these empirical and theoretical results suggest a metabolic efficiency of synaptically stored information.NEW & NOTEWORTHY Learning and memory involve a sequence of molecular events in dendritic spines called synaptic plasticity. These events are physical in nature and require energy, which has to be supplied by ATP molecules. However, our knowledge of the energetics of these processes is very poor. This study estimates the empirical energy cost of synaptic plasticity and considers theoretically a metabolic rate of learning and its memory trace in a class of cascade models of synaptic plasticity.
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Affiliation(s)
- Jan Karbowski
- Institute of Applied Mathematics and Mechanics, University of Warsaw, Warsaw, Poland.,Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
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136
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Glasgow SD, McPhedrain R, Madranges JF, Kennedy TE, Ruthazer ES. Approaches and Limitations in the Investigation of Synaptic Transmission and Plasticity. Front Synaptic Neurosci 2019; 11:20. [PMID: 31396073 PMCID: PMC6667546 DOI: 10.3389/fnsyn.2019.00020] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/04/2019] [Indexed: 12/16/2022] Open
Abstract
The numbers and strengths of synapses in the brain change throughout development, and even into adulthood, as synaptic inputs are added, eliminated, and refined in response to ongoing neural activity. A number of experimental techniques can assess these changes, including single-cell electrophysiological recording which offers measurements of synaptic inputs with high temporal resolution. Coupled with electrical stimulation, photoactivatable opsins, and caged compounds, to facilitate fine spatiotemporal control over release of neurotransmitters, electrophysiological recordings allow for precise dissection of presynaptic and postsynaptic mechanisms of action. Here, we discuss the strengths and pitfalls of various techniques commonly used to analyze synapses, including miniature excitatory/inhibitory (E/I) postsynaptic currents, evoked release, and optogenetic stimulation. Together, these techniques can provide multiple lines of convergent evidence to generate meaningful insight into the emergence of circuit connectivity and maturation. A full understanding of potential caveats and alternative explanations for findings is essential to avoid data misinterpretation.
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Affiliation(s)
| | | | | | | | - Edward S. Ruthazer
- Department of Neurology & Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
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137
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How mRNA Localization and Protein Synthesis Sites Influence Dendritic Protein Distribution and Dynamics. Neuron 2019; 103:1109-1122.e7. [PMID: 31350097 DOI: 10.1016/j.neuron.2019.06.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 02/21/2019] [Accepted: 06/22/2019] [Indexed: 01/23/2023]
Abstract
Proteins drive the function of neuronal synapses. The synapses are distributed throughout the dendritic arbor, often hundreds of micrometers away from the soma. It is still unclear how somatic and dendritic sources of proteins shape protein distribution and respectively contribute to local protein changes during synaptic plasticity. Here, we present a unique computational framework describing for a given protein species the dendritic distribution of the mRNA and the corresponding protein in a dendrite. Using CaMKIIα as a test case, our model reveals the key role active transport plays in the maintenance of dendritic mRNA and protein levels and predicts the short and long timescales of protein dynamics. Our model reveals the fundamental role of mRNA localization and dendritic mRNA translation in synaptic maintenance and plasticity in distal compartments. We developed a web application for neuroscientists to explore the dynamics of the mRNA or protein of interest.
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138
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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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139
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Wagner W, Lippmann K, Heisler FF, Gromova KV, Lombino FL, Roesler MK, Pechmann Y, Hornig S, Schweizer M, Polo S, Schwarz JR, Eilers J, Kneussel M. Myosin VI Drives Clathrin-Mediated AMPA Receptor Endocytosis to Facilitate Cerebellar Long-Term Depression. Cell Rep 2019; 28:11-20.e9. [DOI: 10.1016/j.celrep.2019.06.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 05/01/2019] [Accepted: 05/31/2019] [Indexed: 11/30/2022] Open
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140
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Deng L, Gao X, Fan G, Yang C. Effects of GDNF-Transfected Marrow Stromal Cells on Rats with Intracerebral Hemorrhage. J Stroke Cerebrovasc Dis 2019; 28:2555-2562. [PMID: 31248739 DOI: 10.1016/j.jstrokecerebrovasdis.2019.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/03/2019] [Accepted: 06/02/2019] [Indexed: 10/26/2022] Open
Abstract
OBJECTIVE The present study aimed to investigate the effects of Mesenchymal stem cells/glial cell line derived neurotrophic factor (MSCs/GDNF) transplantation on nerve reconstruction in rats with intracerebral hemorrhage. METHODS GDNF transduction to MSCs was using adenovirus vector pAdEasy-1-pAdTrack-CMV prepared. Intracerebral hemorrhage (ICH) was induced by injection of collagenase and heparin into the caudate putamen. At the third day after a collagenase-induced ICH, adult male SD rats were randomly divided into saline group, MSCs group and MSCs/GDNF group. Immunofluorescence and RT-PCR were performed to detect the differentiation of MSCs or MSCs with an adenovirus vector encoding GDNF gene in vivo and in vitro. RESULT After 6 hours of induction, both MSCs and MSCs/GDNF expressed neuro or glial specific markers and synaptic-associated proteins (SYN, GAP-43, PSD-95); additionally, they secreted bioactive compounds (BDNF, NGF-β). MSCs/GDNF transplantation, compared to MSCs and saline solution injection, significantly improved neurological functions after ICH. The grafted MSCs or MSCs/GDNF survived in the striatum after 2 weeks of transplantation and expressed the neural cell-specific biomarkers NSE, MAP2, and GFAP. CONCLUSION These findings demonstrate that MSCs/GDNF transplantation contributes to improved neurological function in experimental ICH rats. The mechanisms are possibly due to neuronal replacement and enhanced neurotrophic factor secretion.
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Affiliation(s)
- Li Deng
- Department of Neurobiology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Xiaoqing Gao
- Department of Neurobiology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Guangbi Fan
- Department of Neurobiology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China
| | - Chaoxian Yang
- Department of Neurobiology, Research Center for Preclinical Medicine, Southwest Medical University, Luzhou, Sichuan, China.
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141
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Metzbower SR, Joo Y, Benavides DR, Blanpied TA. Properties of Individual Hippocampal Synapses Influencing NMDA-Receptor Activation by Spontaneous Neurotransmission. eNeuro 2019; 6:ENEURO.0419-18.2019. [PMID: 31110134 PMCID: PMC6541874 DOI: 10.1523/eneuro.0419-18.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 05/05/2019] [Accepted: 05/12/2019] [Indexed: 12/14/2022] Open
Abstract
NMDA receptor (NMDAR) activation is critical for maintenance and modification of synapse strength. Specifically, NMDAR activation by spontaneous glutamate release has been shown to mediate some forms of synaptic plasticity as well as synaptic development. Interestingly, there is evidence that within individual synapses each release mode may be segregated such that postsynaptically there are distinct pools of responsive receptors. To examine potential regulators of NMDAR activation because of spontaneous glutamate release in cultured hippocampal neurons, we used GCaMP6f imaging at single synapses in concert with confocal and super-resolution imaging. Using these single-spine approaches, we found that Ca2+ entry activated by spontaneous release tends to be carried by GluN2B-NMDARs. Additionally, the amount of NMDAR activation varies greatly both between synapses and within synapses, and is unrelated to spine and synapse size, but does correlate loosely with synapse distance from the soma. Despite the critical role of spontaneous activation of NMDARs in maintaining synaptic function, their activation seems to be controlled factors other than synapse size or synapse distance from the soma. It is most likely that NMDAR activation by spontaneous release influenced variability in subsynaptic receptor position, release site position, vesicle content, and channel properties. Therefore, spontaneous activation of NMDARs appears to be regulated distinctly from other receptor types, notably AMPARs, within individual synapses.
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Affiliation(s)
| | - Yuyoung Joo
- Department of Neurology, University of Maryland School of Medicine, Baltimore, Maryland, 21201
| | - David R Benavides
- Department of Neurology, University of Maryland School of Medicine, Baltimore, Maryland, 21201
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142
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Lappalainen J, Herpich J, Tetzlaff C. A Theoretical Framework to Derive Simple, Firing-Rate-Dependent Mathematical Models of Synaptic Plasticity. Front Comput Neurosci 2019; 13:26. [PMID: 31133837 PMCID: PMC6517541 DOI: 10.3389/fncom.2019.00026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/10/2019] [Indexed: 11/13/2022] Open
Abstract
Synaptic plasticity serves as an essential mechanism underlying cognitive processes as learning and memory. For a better understanding detailed theoretical models combine experimental underpinnings of synaptic plasticity and match experimental results. However, these models are mathematically complex impeding the comprehensive investigation of their link to cognitive processes generally executed on the neuronal network level. Here, we derive a mathematical framework enabling the simplification of such detailed models of synaptic plasticity facilitating further mathematical analyses. By this framework we obtain a compact, firing-rate-dependent mathematical formulation, which includes the essential dynamics of the detailed model and, thus, of experimentally verified properties of synaptic plasticity. Amongst others, by testing our framework by abstracting the dynamics of two well-established calcium-dependent synaptic plasticity models, we derived that the synaptic changes depend on the square of the presynaptic firing rate, which is in contrast to previous assumptions. Thus, the here-presented framework enables the derivation of biologically plausible but simple mathematical models of synaptic plasticity allowing to analyze the underlying dependencies of synaptic dynamics from neuronal properties such as the firing rate and to investigate their implications in complex neuronal networks.
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Affiliation(s)
- Janne Lappalainen
- Department of Computational Neuroscience, Third Institute of Physics-Biophysics, Georg-August-University, Göttingen, Germany
| | - Juliane Herpich
- Department of Computational Neuroscience, Third Institute of Physics-Biophysics, Georg-August-University, Göttingen, Germany.,Bernstein Center for Computational Neuroscience, Georg-August-University, Göttingen, Germany
| | - Christian Tetzlaff
- Department of Computational Neuroscience, Third Institute of Physics-Biophysics, Georg-August-University, Göttingen, Germany.,Bernstein Center for Computational Neuroscience, Georg-August-University, Göttingen, Germany
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143
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Barberis A. Postsynaptic plasticity of GABAergic synapses. Neuropharmacology 2019; 169:107643. [PMID: 31108109 DOI: 10.1016/j.neuropharm.2019.05.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 12/18/2022]
Abstract
The flexibility of neuronal networks is believed to rely mainly on the plasticity of excitatory synapses. However, like their excitatory counterparts, inhibitory synapses also undergo several forms of synaptic plasticity. This review examines recent advances in the understanding of the molecular mechanisms leading to postsynaptic GABAergic plasticity. Specifically, modulation of GABAA receptor (GABAAR) number at postsynaptic sites plays a key role, with the interaction of GABAARs with the scaffold protein gephyrin and other postsynaptic scaffold/regulatory proteins having particular importance. Our understanding of these molecular interactions are progressing, based on recent insights into the processes of GABAAR lateral diffusion, gephyrin dynamics, and gephyrin nanoscale organization. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Andrea Barberis
- Plasticity of Inhibitory Networks, Fondazione Istituto Italiano di Tecnologia, Via Morego 30, Genova, Italy.
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144
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Dupuis JP, Groc L. Surface trafficking of neurotransmitter receptors: From cultured neurons to intact brain preparations. Neuropharmacology 2019; 169:107642. [PMID: 31108111 DOI: 10.1016/j.neuropharm.2019.05.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 12/14/2022]
Abstract
Over the last decade, developments in single molecule imaging have changed our vision of synaptic physiology. By providing high spatio-temporal resolution maps of the molecular actors of neurotransmissions, these techniques have revealed that pre- and post-synaptic proteins are not randomly distributed but precisely organized at the nanoscale, and that this specific organization is dynamically regulated. At the centre of synaptic transmissions, neurotransmitter receptors have been shown to form nanodomains at synapses and to dynamically move in and out of these confinement areas through lateral diffusion within the membrane plane on millisecond timescales, thereby directly contributing to the regulation of synaptic transmission and plasticity. Since the vast majority of these discoveries originated from observations made on dissociated neurons lacking several features of brain tissue (e.g. three-dimensional organization, tissue density), they were initially considered with caution. However, the recent implementation of single-particle tracking (SPT) approaches in cultured and acute brain preparations confirmed that early findings on the dynamic properties of receptors at the surface of neurons can be extended to more physiological conditions. Taking example of dopamine D1 and NMDA glutamate receptors we here review our current knowledge of the features of neurotransmitter receptor surface diffusion in intact brain tissue. Through detailed comparison with cultured neurons, we also discuss how these biophysical properties are influenced by the complexity of the extracellular environment. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Julien P Dupuis
- Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000, Bordeaux, France; CNRS, IINS UMR 5297, 33000, Bordeaux, France
| | - Laurent Groc
- Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000, Bordeaux, France; CNRS, IINS UMR 5297, 33000, Bordeaux, France.
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145
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Guzman GA, Guzman RE, Jordan N, Hidalgo P. A Tripartite Interaction Among the Calcium Channel α 1- and β-Subunits and F-Actin Increases the Readily Releasable Pool of Vesicles and Its Recovery After Depletion. Front Cell Neurosci 2019; 13:125. [PMID: 31130843 PMCID: PMC6509170 DOI: 10.3389/fncel.2019.00125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/13/2019] [Indexed: 11/13/2022] Open
Abstract
Neurotransmitter release is initiated by the influx of Ca2+via voltage-gated calcium channels. The accessory β-subunit (CaVβ) of these channels shapes synaptic transmission by associating with the pore-forming subunit (CaVα1) and up-regulating presynaptic calcium currents. Besides CaVα1, CaVβ interacts with several partners including actin filaments (F-actin). These filaments are known to associate with synaptic vesicles (SVs) at the presynaptic terminals and support their translocation within different pools, but the role of CaVβ/F-actin association on synaptic transmission has not yet been explored. We here study how CaVβ4, the major calcium channel β isoform in mamalian brain, modifies synaptic transmission in concert with F-actin in cultured hippocampal neurons. We analyzed the effect of exogenous CaVβ4 before and after pharmacological disruption of the actin cytoskeleton and dissected calcium channel-dependent and -independent functions by comparing the effects of the wild-type subunit with the one bearing a double mutation that impairs binding to CaVα1. We found that exogenously expressed wild-type CaVβ4 enhances spontaneous and depolarization-evoked excitatory postsynaptic currents (EPSCs) without altering synaptogenesis. CaVβ4 increases the size of the readily releasable pool (RRP) of SVs at resting conditions and accelerates their recovery after depletion. The enhanced neurotransmitter release induced by CaVβ4 is abolished upon disruption of the actin cytoskeleton. The CaVα1 association-deficient CaVβ4 mutant associates with actin filaments, but neither alters postsynaptic responses nor the time course of the RRP recovery. Furthermore, this mutant protein preserves the ability to increase the RRP size. These results indicate that the interplay between CaVβ4 and F-actin also support the recruitment of SVs to the RRP in a CaVα1-independent manner. Our studies show an emerging role of CaVβ in determining SV maturation toward the priming state and its replenishment after release. We envision that this subunit plays a role in coupling exocytosis to endocytosis during the vesicle cycle.
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Affiliation(s)
- Gustavo A Guzman
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Raul E Guzman
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Nadine Jordan
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany
| | - Patricia Hidalgo
- Institute of Complex Systems 4, Zelluläre Biophysik, Forschungszentrum Jülich, Jülich, Germany.,Institute of Biochemistry, Heinrich-Heine University, Düsseldorf, Germany
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146
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Dürst CD, Wiegert JS, Helassa N, Kerruth S, Coates C, Schulze C, Geeves MA, Török K, Oertner TG. High-speed imaging of glutamate release with genetically encoded sensors. Nat Protoc 2019; 14:1401-1424. [PMID: 30988508 PMCID: PMC6751072 DOI: 10.1038/s41596-019-0143-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/22/2019] [Indexed: 11/08/2022]
Abstract
The strength of an excitatory synapse depends on its ability to release glutamate and on the density of postsynaptic receptors. Genetically encoded glutamate indicators (GEGIs) allow eavesdropping on synaptic transmission at the level of cleft glutamate to investigate properties of the release machinery in detail. Based on the sensor iGluSnFR, we recently developed accelerated versions of GEGIs that allow investigation of synaptic release during 100-Hz trains. Here, we describe the detailed procedures for design and characterization of fast iGluSnFR variants in vitro, transfection of pyramidal cells in organotypic hippocampal cultures, and imaging of evoked glutamate transients with two-photon laser-scanning microscopy. As the released glutamate spreads from a point source-the fusing vesicle-it is possible to localize the vesicle fusion site with a precision exceeding the optical resolution of the microscope. By using a spiral scan path, the temporal resolution can be increased to 1 kHz to capture the peak amplitude of fast iGluSnFR transients. The typical time frame for these experiments is 30 min per synapse.
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Affiliation(s)
- Céline D Dürst
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Hamburg, Germany
| | - J Simon Wiegert
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Hamburg, Germany
- Research Group Synaptic Wiring and Information Processing, Center for Molecular Neurobiology Hamburg, Hamburg, Germany
| | - Nordine Helassa
- Molecular and Clinical Sciences Research Institute, St George's, University of London, London, UK
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - Silke Kerruth
- Molecular and Clinical Sciences Research Institute, St George's, University of London, London, UK
- Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry, Prague, Czech Republic
| | - Catherine Coates
- Molecular and Clinical Sciences Research Institute, St George's, University of London, London, UK
| | - Christian Schulze
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Hamburg, Germany
| | | | - Katalin Török
- Molecular and Clinical Sciences Research Institute, St George's, University of London, London, UK
| | - Thomas G Oertner
- Institute for Synaptic Physiology, Center for Molecular Neurobiology Hamburg, Hamburg, Germany.
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147
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Kudryashova IV. The Molecular Basis of Destabilization of Synapses as a Factor of Structural Plasticity. NEUROCHEM J+ 2019. [DOI: 10.1134/s1819712419010136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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148
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Kula B, Chen T, Kukley M. Glutamatergic signaling between neurons and oligodendrocyte lineage cells: Is it synaptic or non‐synaptic? Glia 2019; 67:2071-2091. [DOI: 10.1002/glia.23617] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/12/2019] [Accepted: 03/18/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Bartosz Kula
- Group of Neuron Glia InteractionUniversity of Tübingen Tübingen Germany
- Graduate Training Centre for NeuroscienceUniversity of Tübingen Tübingen Germany
| | - Ting‐Jiun Chen
- Center for Neuroscience ResearchChildren's Research Institute, Children's National Medical Center Washington District of Columbia
| | - Maria Kukley
- Group of Neuron Glia InteractionUniversity of Tübingen Tübingen Germany
- Research Institute for OphthalmologyUniversity Hospital Tübingen Tübingen Germany
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149
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Shao L, Wang H, Yang Y, He Y, Tang Y, Fang H, Zhao J, Xiao H, Liang K, Wei M, Xu W, Luo M, Wan Q, Hu W, Gao T, Cui Z. Optoelectronic Properties of Printed Photogating Carbon Nanotube Thin Film Transistors and Their Application for Light-Stimulated Neuromorphic Devices. ACS APPLIED MATERIALS & INTERFACES 2019; 11:12161-12169. [PMID: 30817113 DOI: 10.1021/acsami.9b02086] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Artificial synapses/neurons based on electronic/ionic hybrid devices have attracted wide attention for brain-inspired neuromorphic systems since it is possible to overcome the von Neumann bottleneck of the neuromorphic computing paradigm. Here, we report a novel photoneuromorphic device based on printed photogating single-walled carbon nanotube (SWCNT) thin film transistors (TFTs) using lightly n-doped Si as the gate electrode. The drain currents of the printed SWCNT TFTs can gradually increase to over 3000 times of their starting value after being pulsed with light stimulation, and the electrical signals can maintain for over 10 min. These characteristics are similar to the learning and memory functions of brain-inspired neuromorphic systems. The working mechanism of the light-stimulated neuromorphic devices is investigated and described here in detail. Important synaptic characteristics, such as low-pass filtering characteristics and nonvolatile memory ability, are successfully emulated in the printed light-stimulated artificial synapses. It demonstrates that the printed SWCNT TFT photoneuromorphic devices can act as the nonvolatile memory units and perform photoneuromorphic computing, which exhibits potential for future neuromorphic system applications.
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Affiliation(s)
- Lin Shao
- College of Nano Technology and Nano Bionics , University of Science and Technology of China , 96 Jinzhai Road , Hefei 230026 , P.R. China
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Hailu Wang
- State Key Laboratory of Infrared Physics , Shanghai Institute of Technical Physics, Chinese Academy of Sciences , 500 Yutian Road , Shanghai 200083 , P.R. China
| | - Yi Yang
- School of Electronic Science and Engineering, and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , 163 Xianlin Road , Nanjing 210093 , P.R. China
| | - Yongli He
- School of Electronic Science and Engineering, and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , 163 Xianlin Road , Nanjing 210093 , P.R. China
| | - Yicheng Tang
- State Key Laboratory of Infrared Physics , Shanghai Institute of Technical Physics, Chinese Academy of Sciences , 500 Yutian Road , Shanghai 200083 , P.R. China
| | - Hehai Fang
- State Key Laboratory of Infrared Physics , Shanghai Institute of Technical Physics, Chinese Academy of Sciences , 500 Yutian Road , Shanghai 200083 , P.R. China
| | - Jianwen Zhao
- College of Nano Technology and Nano Bionics , University of Science and Technology of China , 96 Jinzhai Road , Hefei 230026 , P.R. China
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Hongshan Xiao
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Kun Liang
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Miaomiao Wei
- College of Nano Technology and Nano Bionics , University of Science and Technology of China , 96 Jinzhai Road , Hefei 230026 , P.R. China
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Wenya Xu
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Manman Luo
- College of Nano Technology and Nano Bionics , University of Science and Technology of China , 96 Jinzhai Road , Hefei 230026 , P.R. China
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Qing Wan
- School of Electronic Science and Engineering, and Collaborative Innovation Center of Advanced Microstructures , Nanjing University , 163 Xianlin Road , Nanjing 210093 , P.R. China
| | - Weida Hu
- State Key Laboratory of Infrared Physics , Shanghai Institute of Technical Physics, Chinese Academy of Sciences , 500 Yutian Road , Shanghai 200083 , P.R. China
| | - Tianqi Gao
- College of Nano Technology and Nano Bionics , University of Science and Technology of China , 96 Jinzhai Road , Hefei 230026 , P.R. China
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
| | - Zheng Cui
- College of Nano Technology and Nano Bionics , University of Science and Technology of China , 96 Jinzhai Road , Hefei 230026 , P.R. China
- Printable Electronics Research Centre , Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science , 398 Ruoshui Road , Suzhou 215123 , P.R. China
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150
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Postsynaptic protein organization revealed by electron microscopy. Curr Opin Struct Biol 2019; 54:152-160. [PMID: 30904821 PMCID: PMC6753054 DOI: 10.1016/j.sbi.2019.02.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/02/2019] [Accepted: 02/18/2019] [Indexed: 11/21/2022]
Abstract
Neuronal synapses are key devices for transmitting and processing information in the nervous system. Synaptic plasticity, generally regarded as the cellular basis of learning and memory, involves changes of subcellular structures that take place at the nanoscale. High-resolution imaging methods, especially electron microscopy (EM), have allowed for quantitative analysis of such nanoscale structures in different types of synapses. In particular, the semi-ordered organization of neurotransmitter receptors and their interacting scaffolds in the postsynaptic density have been characterized for both excitatory and inhibitory synapses by studies using various EM techniques such as immuno-EM, electron tomography of high-pressure freezing and freeze-substituted samples, and cryo electron tomography. These techniques, in combination with new correlative approaches, will further facilitate our understanding of the molecular organization underlying diverse functions of neuronal synapses.
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