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McFadden MH, Emeritt MB, Xu H, Cui Y, Leterrier C, Zala D, Venance L, Lenkei Z. Actomyosin-mediated inhibition of synaptic vesicle release under CB 1R activation. Transl Psychiatry 2024; 14:335. [PMID: 39168993 PMCID: PMC11339458 DOI: 10.1038/s41398-024-03017-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 04/16/2024] [Accepted: 07/08/2024] [Indexed: 08/23/2024] Open
Abstract
Long-term synaptic plasticity is critical for adaptive function of the brain, but presynaptic mechanisms of functional plasticity remain poorly understood. Here, we show that changes in synaptic efficacy induced by activation of the cannabinoid type-1 receptor (CB1R), one of the most widespread G-protein coupled receptors in the brain, requires contractility of the neuronal actomyosin cytoskeleton. Specifically, using a synaptophysin-pHluorin probe (sypH2), we show that inhibitors of non-muscle myosin II (NMII) ATPase as well as one of its upstream effectors Rho-associated kinase (ROCK) prevent the reduction of synaptic vesicle release induced by CB1R activation. Using 3D STORM super-resolution microscopy, we find that activation of CB1R induces a redistribution of synaptic vesicles within presynaptic boutons in an actomyosin dependent manner, leading to vesicle clustering within the bouton and depletion of synaptic vesicles from the active zone. We further show, using sypH2, that inhibitors of NMII and ROCK specifically restore the release of the readily releasable pool of synaptic vesicles from the inhibition induced by CB1R activation. Finally, using slice electrophysiology, we find that activation of both NMII and ROCK is necessary for the long-term, but not the short-term, form of CB1R induced synaptic plasticity at excitatory cortico-striatal synapses. We thus propose a novel mechanism underlying CB1R-induced plasticity, whereby CB1R activation leads to a contraction of the actomyosin cytoskeleton inducing a reorganization of the functional presynaptic vesicle pool, preventing vesicle release and inducing long-term depression.
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Affiliation(s)
- Maureen H McFadden
- Institut Pasteur, Université Paris Cité, Synapse and Circuit Dynamics Laboratory, CNRS UMR 3571, Paris, France
- Brain Plasticity Unit, ESPCI Paris, PSL Research University, CNRS, Paris, France
| | - Michel-Boris Emeritt
- Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, INSERM U1266, Paris, France
| | - Hao Xu
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Yihui Cui
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | | | - Diana Zala
- Brain Plasticity Unit, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, INSERM U1266, Paris, France
| | - Laurent Venance
- Dynamics and Pathophysiology of Neuronal Networks Team, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Zsolt Lenkei
- Brain Plasticity Unit, ESPCI Paris, PSL Research University, CNRS, Paris, France.
- Institute of Psychiatry and Neuroscience of Paris (IPNP), Université Paris Cité, INSERM U1266, Paris, France.
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2
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Kohler J, Hur KH, Mueller JD. Statistical analysis of the autocorrelation function in fluorescence correlation spectroscopy. Biophys J 2024; 123:667-680. [PMID: 38219016 PMCID: PMC10995414 DOI: 10.1016/j.bpj.2024.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/24/2023] [Accepted: 01/09/2024] [Indexed: 01/15/2024] Open
Abstract
Fluorescence correlation spectroscopy (FCS) is a powerful method to measure concentration, mobility, and stoichiometry in solution and in living cells, but quantitative analysis of FCS data remains challenging due to the correlated noise in the autocorrelation function (ACF) of FCS. We demonstrate here that least-squares fitting of the conventional ACF is incompatible with the χ2 goodness-of-fit test and systematically underestimates the true fit parameter uncertainty. To overcome this challenge, a simple method to fit the ACF is introduced that allows proper calculation of goodness-of-fit statistics and that provides more tightly constrained parameter estimates than the conventional least-squares fitting method, achieving the theoretical minimum uncertainty. Because this method requires significantly more data than the standard method, we further introduce an approximate method that requires fewer data. We demonstrate both these new methods using experiments and simulations of diffusion. Finally, we apply our method to FCS data of the peripheral membrane protein HRas, which has a slow-diffusing membrane-bound population and a fast-diffusing cytoplasmic population. Despite the order-of-magnitude difference of the diffusion times, conventional FCS fails to reliably resolve the two species, whereas the new method identifies the correct model and provides robust estimates of the fit parameters for both species.
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Affiliation(s)
- John Kohler
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota
| | - Kwang-Ho Hur
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota
| | - Joachim Dieter Mueller
- School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota; Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.
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3
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Longfield SF, Gormal RS, Feller M, Parutto P, Reingruber J, Wallis TP, Joensuu M, Augustine GJ, Martínez-Mármol R, Holcman D, Meunier FA. Synapsin 2a tetramerisation selectively controls the presynaptic nanoscale organisation of reserve synaptic vesicles. Nat Commun 2024; 15:2217. [PMID: 38472171 PMCID: PMC10933366 DOI: 10.1038/s41467-024-46256-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 02/21/2024] [Indexed: 03/14/2024] Open
Abstract
Neurotransmitter release relies on the regulated fusion of synaptic vesicles (SVs) that are tightly packed within the presynaptic bouton of neurons. The mechanism by which SVs are clustered at the presynapse, while preserving their ability to dynamically recycle to support neuronal communication, remains unknown. Synapsin 2a (Syn2a) tetramerization has been suggested as a potential clustering mechanism. Here, we used Dual-pulse sub-diffractional Tracking of Internalised Molecules (DsdTIM) to simultaneously track single SVs from the recycling and the reserve pools, in live hippocampal neurons. The reserve pool displays a lower presynaptic mobility compared to the recycling pool and is also present in the axons. Triple knockout of Synapsin 1-3 genes (SynTKO) increased the mobility of reserve pool SVs. Re-expression of wild-type Syn2a (Syn2aWT), but not the tetramerization-deficient mutant K337Q (Syn2aK337Q), fully rescued these effects. Single-particle tracking revealed that Syn2aK337QmEos3.1 exhibited altered activity-dependent presynaptic translocation and nanoclustering. Therefore, Syn2a tetramerization controls its own presynaptic nanoclustering and thereby contributes to the dynamic immobilisation of the SV reserve pool.
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Affiliation(s)
- Shanley F Longfield
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Matis Feller
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
| | - Pierre Parutto
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
| | - Jürgen Reingruber
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
| | - Tristan P Wallis
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | | | - Ramón Martínez-Mármol
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - David Holcman
- Group of Data Modelling and Computational Biology, IBENS, Ecole Normale Superieure, 75005, Paris, France
- Department of Applied Mathematics and Theoretical Physics (DAMPT) visitor, University of Cambridge, and Churchill College, CB30DS, Cambridge, UK
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
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4
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Park C, Jung S, Park H. Single vesicle tracking for studying synaptic vesicle dynamics in small central synapses. Curr Opin Neurobiol 2022; 76:102596. [PMID: 35803103 DOI: 10.1016/j.conb.2022.102596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/20/2022] [Accepted: 05/27/2022] [Indexed: 11/26/2022]
Abstract
Sustained neurotransmission is driven by a continuous supply of synaptic vesicles to the release sites and modulated by synaptic vesicle dynamics. However, synaptic vesicle dynamics in synapses remain elusive because of technical limitations. Recent advances in fluorescence imaging techniques have enabled the tracking of single synaptic vesicles in small central synapses in living neurons. Single vesicle tracking has uncovered a wealth of new information about synaptic vesicle dynamics both within and outside presynaptic terminals, showing that single vesicle tracking is an effective tool for studying synaptic vesicle dynamics. Particularly, single vesicle tracking with high spatiotemporal resolution has revealed the dependence of synaptic vesicle dynamics on the location, stages of recycling, and neuronal activity. This review summarizes the recent findings from single synaptic vesicle tracking in small central synapses and their implications in synaptic transmission and pathogenic mechanisms of neurodegenerative diseases.
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Affiliation(s)
- Chungwon Park
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong
| | - Sangyong Jung
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 11 Biopolis Way, 138667, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 119077, Singapore
| | - Hyokeun Park
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong; Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong.
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5
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Reshetniak S, Ußling J, Perego E, Rammner B, Schikorski T, Fornasiero EF, Truckenbrodt S, Köster S, Rizzoli SO. A comparative analysis of the mobility of 45 proteins in the synaptic bouton. EMBO J 2020; 39:e104596. [PMID: 32627850 PMCID: PMC7429486 DOI: 10.15252/embj.2020104596] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/20/2020] [Accepted: 05/29/2020] [Indexed: 02/01/2023] Open
Abstract
Many proteins involved in synaptic transmission are well known, and their features, as their abundance or spatial distribution, have been analyzed in systematic studies. This has not been the case, however, for their mobility. To solve this, we analyzed the motion of 45 GFP-tagged synaptic proteins expressed in cultured hippocampal neurons, using fluorescence recovery after photobleaching, particle tracking, and modeling. We compared synaptic vesicle proteins, endo- and exocytosis cofactors, cytoskeleton components, and trafficking proteins. We found that movement was influenced by the protein association with synaptic vesicles, especially for membrane proteins. Surprisingly, protein mobility also correlated significantly with parameters as the protein lifetimes, or the nucleotide composition of their mRNAs. We then analyzed protein movement thoroughly, taking into account the spatial characteristics of the system. This resulted in a first visualization of overall protein motion in the synapse, which should enable future modeling studies of synaptic physiology.
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Affiliation(s)
- Sofiia Reshetniak
- Institute for Neuro‐ and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) CenterUniversity Medical Center GöttingenGöttingenGermany
- International Max Planck Research School for Molecular BiologyGöttingenGermany
| | - Jan‐Eike Ußling
- Institute for Neuro‐ and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) CenterUniversity Medical Center GöttingenGöttingenGermany
| | - Eleonora Perego
- Institute for X‐Ray PhysicsUniversity of GöttingenGöttingenGermany
| | - Burkhard Rammner
- Institute for Neuro‐ and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) CenterUniversity Medical Center GöttingenGöttingenGermany
| | - Thomas Schikorski
- Department of NeuroscienceUniversidad Central del CaribeBayamonPRUSA
| | - Eugenio F Fornasiero
- Institute for Neuro‐ and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) CenterUniversity Medical Center GöttingenGöttingenGermany
| | - Sven Truckenbrodt
- Institute for Neuro‐ and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) CenterUniversity Medical Center GöttingenGöttingenGermany
- International Max Planck Research School for Molecular BiologyGöttingenGermany
| | - Sarah Köster
- Institute for X‐Ray PhysicsUniversity of GöttingenGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
| | - Silvio O Rizzoli
- Institute for Neuro‐ and Sensory Physiology and Biostructural Imaging of Neurodegeneration (BIN) CenterUniversity Medical Center GöttingenGöttingenGermany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC)University of GöttingenGöttingenGermany
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6
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Toni M, Angiulli E, Miccoli G, Cioni C, Alleva E, Frabetti F, Pizzetti F, Grassi Scalvini F, Nonnis S, Negri A, Tedeschi G, Maffioli E. Environmental temperature variation affects brain protein expression and cognitive abilities in adult zebrafish (Danio rerio): A proteomic and behavioural study. J Proteomics 2019; 204:103396. [DOI: 10.1016/j.jprot.2019.103396] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/30/2019] [Accepted: 05/24/2019] [Indexed: 11/26/2022]
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7
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Joensuu M, Martínez-Mármol R, Padmanabhan P, Glass NR, Durisic N, Pelekanos M, Mollazade M, Balistreri G, Amor R, Cooper-White JJ, Goodhill GJ, Meunier FA. Visualizing endocytic recycling and trafficking in live neurons by subdiffractional tracking of internalized molecules. Nat Protoc 2017; 12:2590-2622. [PMID: 29189775 DOI: 10.1038/nprot.2017.116] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Our understanding of endocytic pathway dynamics is restricted by the diffraction limit of light microscopy. Although super-resolution techniques can overcome this issue, highly crowded cellular environments, such as nerve terminals, can also dramatically limit the tracking of multiple endocytic vesicles such as synaptic vesicles (SVs), which in turn restricts the analytical dissection of their discrete diffusional and transport states. We recently introduced a pulse-chase technique for subdiffractional tracking of internalized molecules (sdTIM) that allows the visualization of fluorescently tagged molecules trapped in individual signaling endosomes and SVs in presynapses or axons with 30- to 50-nm localization precision. We originally developed this approach for tracking single molecules of botulinum neurotoxin type A, which undergoes activity-dependent internalization and retrograde transport in autophagosomes. This method was then adapted to localize the signaling endosomes containing cholera toxin subunit-B that undergo retrograde transport in axons and to track SVs in the crowded environment of hippocampal presynapses. We describe (i) the construction of a custom-made microfluidic device that enables control over neuronal orientation; (ii) the 3D printing of a perfusion system for sdTIM experiments performed on glass-bottom dishes; (iii) the dissection, culturing and transfection of hippocampal neurons in microfluidic devices; and (iv) guidance on how to perform the pulse-chase experiments and data analysis. In addition, we describe the use of single-molecule-tracking analytical tools to reveal the average and the heterogeneous single-molecule mobility behaviors. We also discuss alternative reagents and equipment that can, in principle, be used for sdTIM experiments and describe how to adapt sdTIM to image nanocluster formation and/or tubulation in early endosomes during sorting events. The procedures described in this protocol take ∼1 week.
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Affiliation(s)
- Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Ramon Martínez-Mármol
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Pranesh Padmanabhan
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Nick R Glass
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland, Australia
| | - Nela Durisic
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Matthew Pelekanos
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Mahdie Mollazade
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Giuseppe Balistreri
- Division of General Microbiology, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Rumelo Amor
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Justin J Cooper-White
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland, Australia.,Division of General Microbiology, Department of Biosciences, University of Helsinki, Helsinki, Finland.,School of Chemical Engineering, The University of Queensland, Brisbane, Queensland, Australia.,Materials Science and Engineering Division, CSIRO, Clayton, Victoria, Australia.,UQ Centre for Stem Cell Ageing and Regenerative Engineering, The University of Queensland, Brisbane, Queensland, Australia
| | - Geoffrey J Goodhill
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia.,School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
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8
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Satnav for cells: Destination membrane fusion. Cell Calcium 2017; 68:14-23. [PMID: 29129204 DOI: 10.1016/j.ceca.2017.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 09/20/2017] [Accepted: 10/07/2017] [Indexed: 11/23/2022]
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9
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Macias-Medri AE, Liendo JA, Silva RJ. An electrostatic and probabilistic simulation model to describe neurosecretion at the synaptic scale. NETWORK (BRISTOL, ENGLAND) 2017; 28:53-73. [PMID: 29120672 DOI: 10.1080/0954898x.2017.1386806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A hybrid simulation model (macro-molecular dynamics and Monte Carlo method) is proposed to reproduce neurosecretion and exocytosis. A theory has been developed for vesicular dynamics based on quasi-static electric interactions and a simple transition-state model for the vesicular fusion. Under the non-equilibrium electric conditions in an electrolytic fluid, it is considered that the motion of each synaptic vesicle is influenced by electrostatic forces exerted by the membranes of the synaptic bouton, other vesicles, the intracellular and intravesicular fluids, and external elements to the neuron. In addition, friction between each vesicle and its surrounding intracellular fluid is included in the theory, resulting in a drift type movement. To validate the vesicle equations of motion, a molecular dynamics method has been implemented, where the synaptic pool was replaced by a straight angle parallelepiped, the vesicles were represented by spheres and the fusion between each vesicle and the presynaptic membrane was simulated by a Monte Carlo type probabilistic change of state. Density profiles showing clusters of preferential activity as well as fusion distributions similar to the Poisson distributions associated with miniature end-plate potentials were obtained in the simulations.
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Affiliation(s)
- A E Macias-Medri
- a Departamento de Física , Universidade Federal do Paraná , Curitiba , Brazil
| | - Jacinto A Liendo
- b Physics Department , Simón Bolívar University , Baruta , Venezuela
| | - Ricardo J Silva
- c Instituto Montenegro para la Investigación y Desarrollo de las Neurociencias Cognitivas , Unidad Médica I de la Clínica San Francisco , Guayaquil , Ecuador
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10
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Activity-Dependence of Synaptic Vesicle Dynamics. J Neurosci 2017; 37:10597-10610. [PMID: 28954868 DOI: 10.1523/jneurosci.0383-17.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 08/08/2017] [Accepted: 08/15/2017] [Indexed: 11/21/2022] Open
Abstract
The proper function of synapses relies on efficient recycling of synaptic vesicles. The small size of synaptic boutons has hampered efforts to define the dynamical states of vesicles during recycling. Moreover, whether vesicle motion during recycling is regulated by neural activity remains largely unknown. We combined nanoscale-resolution tracking of individual synaptic vesicles in cultured hippocampal neurons from rats of both sexes with advanced motion analyses to demonstrate that the majority of recently endocytosed vesicles undergo sequences of transient dynamical states including epochs of directed, diffusional, and stalled motion. We observed that vesicle motion is modulated in an activity-dependent manner, with dynamical changes apparent in ∼20% of observed boutons. Within this subpopulation of boutons, 35% of observed vesicles exhibited acceleration and 65% exhibited deceleration, accompanied by corresponding changes in directed motion. Individual vesicles observed in the remaining ∼80% of boutons did not exhibit apparent dynamical changes in response to stimulation. More quantitative transient motion analyses revealed that the overall reduction of vesicle mobility, and specifically of the directed motion component, is the predominant activity-evoked change across the entire bouton population. Activity-dependent modulation of vesicle mobility may represent an important mechanism controlling vesicle availability and neurotransmitter release.SIGNIFICANCE STATEMENT Mechanisms governing synaptic vesicle dynamics during recycling remain poorly understood. Using nanoscale resolution tracking of individual synaptic vesicles in hippocampal synapses and advanced motion analysis tools we demonstrate that synaptic vesicles undergo complex sets of dynamical states that include epochs of directed, diffusive, and stalled motion. Most importantly, our analyses revealed that vesicle motion is modulated in an activity-dependent manner apparent as the reduction in overall vesicle mobility in response to stimulation. These results define the vesicle dynamical states during recycling and reveal their activity-dependent modulation. Our study thus provides fundamental new insights into the principles governing synaptic function.
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11
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Guillaud L, Dimitrov D, Takahashi T. Presynaptic morphology and vesicular composition determine vesicle dynamics in mouse central synapses. eLife 2017; 6. [PMID: 28432787 PMCID: PMC5423771 DOI: 10.7554/elife.24845] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 04/18/2017] [Indexed: 11/13/2022] Open
Abstract
Transport of synaptic vesicles (SVs) in nerve terminals is thought to play essential roles in maintenance of neurotransmission. To identify factors modulating SV movements, we performed real-time imaging analysis of fluorescently labeled SVs in giant calyceal and conventional hippocampal terminals. Compared with small hippocampal terminals, SV movements in giant calyceal terminals were faster, longer and kinetically more heterogeneous. Morphological maturation of giant calyceal terminals was associated with an overall reduction in SV mobility and displacement heterogeneity. At the molecular level, SVs over-expressing vesicular glutamate transporter 1 (VGLUT1) showed higher mobility than VGLUT2-expressing SVs. Pharmacological disruption of the presynaptic microtubule network preferentially reduced long directional movements of SVs between release sites. Functionally, synaptic stimulation appeared to recruit SVs to active zones without significantly altering their mobility. Hence, the morphological features of nerve terminals and the molecular signature of vesicles are key elements determining vesicular dynamics and movements in central synapses.
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Affiliation(s)
- Laurent Guillaud
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Dimitar Dimitrov
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Tomoyuki Takahashi
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
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12
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Joensuu M, Padmanabhan P, Durisic N, Bademosi ATD, Cooper-Williams E, Morrow IC, Harper CB, Jung W, Parton RG, Goodhill GJ, Papadopulos A, Meunier FA. Subdiffractional tracking of internalized molecules reveals heterogeneous motion states of synaptic vesicles. J Cell Biol 2016; 215:277-292. [PMID: 27810917 PMCID: PMC5080683 DOI: 10.1083/jcb.201604001] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 09/30/2016] [Indexed: 11/23/2022] Open
Abstract
Joensuu et al. describe a tool for subdiffractional tracking of internalized molecules. They reveal that synaptic vesicles exhibit stochastic switching between heterogeneous diffusive and transport states in live hippocampal nerve terminals. Our understanding of endocytic pathway dynamics is severely restricted by the diffraction limit of light microscopy. To address this, we implemented a novel technique based on the subdiffractional tracking of internalized molecules (sdTIM). This allowed us to image anti–green fluorescent protein Atto647N-tagged nanobodies trapped in synaptic vesicles (SVs) from live hippocampal nerve terminals expressing vesicle-associated membrane protein 2 (VAMP2)–pHluorin with 36-nm localization precision. Our results showed that, once internalized, VAMP2–pHluorin/Atto647N–tagged nanobodies exhibited a markedly lower mobility than on the plasma membrane, an effect that was reversed upon restimulation in presynapses but not in neighboring axons. Using Bayesian model selection applied to hidden Markov modeling, we found that SVs oscillated between diffusive states or a combination of diffusive and transport states with opposite directionality. Importantly, SVs exhibiting diffusive motion were relatively less likely to switch to the transport motion. These results highlight the potential of the sdTIM technique to provide new insights into the dynamics of endocytic pathways in a wide variety of cellular settings.
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Affiliation(s)
- Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Pranesh Padmanabhan
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nela Durisic
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Adekunle T D Bademosi
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | | | - Isabel C Morrow
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Callista B Harper
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - WooRam Jung
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.,Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Robert G Parton
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.,Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Geoffrey J Goodhill
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.,School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Andreas Papadopulos
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia .,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia .,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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13
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Zhan H, Bruckner J, Zhang Z, O’Connor-Giles K. Three-dimensional imaging of Drosophila motor synapses reveals ultrastructural organizational patterns. J Neurogenet 2016; 30:237-246. [PMID: 27981875 PMCID: PMC5281062 DOI: 10.1080/01677063.2016.1253693] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 10/22/2016] [Accepted: 10/24/2016] [Indexed: 01/18/2023]
Abstract
We combined cryo-preservation of intact Drosophila larvae and electron tomography with comprehensive segmentation of key features to reconstruct the complete ultrastructure of a model glutamatergic synapse in a near-to-native state. Presynaptically, we detail a complex network of filaments that connects and organizes synaptic vesicles. We link the complexity of this synaptic vesicle network to proximity to the active zone cytomatrix, consistent with the model that these protein structures function together to regulate synaptic vesicle pools. We identify a net-shaped network of electron-dense filaments spanning the synaptic cleft that suggests conserved organization of trans-synaptic adhesion complexes at excitatory synapses. Postsynaptically, we characterize a regular pattern of macromolecules that yields structural insights into the scaffolding of neurotransmitter receptors. Together, these analyses reveal an unexpected level of conservation in the nanoscale organization of diverse glutamatergic synapses and provide a structural foundation for understanding the molecular machines that regulate synaptic communication at a powerful model synapse.
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Affiliation(s)
- Hong Zhan
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706
| | - Joseph Bruckner
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706
| | - Ziheng Zhang
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706
| | - Kate O’Connor-Giles
- Laboratory of Cell and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706
- Cell and Molecular Biology Training Program, University of Wisconsin-Madison, Madison, WI 53706
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
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14
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Rothman JS, Kocsis L, Herzog E, Nusser Z, Silver RA. Physical determinants of vesicle mobility and supply at a central synapse. eLife 2016; 5. [PMID: 27542193 PMCID: PMC5025287 DOI: 10.7554/elife.15133] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 08/14/2016] [Indexed: 12/22/2022] Open
Abstract
Encoding continuous sensory variables requires sustained synaptic signalling. At several sensory synapses, rapid vesicle supply is achieved via highly mobile vesicles and specialized ribbon structures, but how this is achieved at central synapses without ribbons is unclear. Here we examine vesicle mobility at excitatory cerebellar mossy fibre synapses which sustain transmission over a broad frequency bandwidth. Fluorescent recovery after photobleaching in slices from VGLUT1Venus knock-in mice reveal 75% of VGLUT1-containing vesicles have a high mobility, comparable to that at ribbon synapses. Experimentally constrained models establish hydrodynamic interactions and vesicle collisions are major determinants of vesicle mobility in crowded presynaptic terminals. Moreover, models incorporating 3D reconstructions of vesicle clouds near active zones (AZs) predict the measured releasable pool size and replenishment rate from the reserve pool. They also show that while vesicle reloading at AZs is not diffusion-limited at the onset of release, diffusion limits vesicle reloading during sustained high-frequency signalling. DOI:http://dx.doi.org/10.7554/eLife.15133.001
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Affiliation(s)
- Jason Seth Rothman
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Laszlo Kocsis
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Etienne Herzog
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany.,Team Synapse in Cognition, Interdisciplinary Institute for Neuroscience, Université de Bordeaux, UMR 5297, F-33000, Bordeaux, France
| | - Zoltan Nusser
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Robin Angus Silver
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
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15
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A nanoscale resolution view on synaptic vesicle dynamics. Synapse 2014; 69:256-67. [DOI: 10.1002/syn.21795] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 11/20/2014] [Accepted: 11/27/2014] [Indexed: 12/31/2022]
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16
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Van Hook MJ, Parmelee CM, Chen M, Cork KM, Curto C, Thoreson WB. Calmodulin enhances ribbon replenishment and shapes filtering of synaptic transmission by cone photoreceptors. ACTA ACUST UNITED AC 2014; 144:357-78. [PMID: 25311636 PMCID: PMC4210432 DOI: 10.1085/jgp.201411229] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
At the first synapse in the vertebrate visual pathway, light-evoked changes in photoreceptor membrane potential alter the rate of glutamate release onto second-order retinal neurons. This process depends on the synaptic ribbon, a specialized structure found at various sensory synapses, to provide a supply of primed vesicles for release. Calcium (Ca(2+)) accelerates the replenishment of vesicles at cone ribbon synapses, but the mechanisms underlying this acceleration and its functional implications for vision are unknown. We studied vesicle replenishment using paired whole-cell recordings of cones and postsynaptic neurons in tiger salamander retinas and found that it involves two kinetic mechanisms, the faster of which was diminished by calmodulin (CaM) inhibitors. We developed an analytical model that can be applied to both conventional and ribbon synapses and showed that vesicle resupply is limited by a simple time constant, τ = 1/(Dρδs), where D is the vesicle diffusion coefficient, δ is the vesicle diameter, ρ is the vesicle density, and s is the probability of vesicle attachment. The combination of electrophysiological measurements, modeling, and total internal reflection fluorescence microscopy of single synaptic vesicles suggested that CaM speeds replenishment by enhancing vesicle attachment to the ribbon. Using electroretinogram and whole-cell recordings of light responses, we found that enhanced replenishment improves the ability of cone synapses to signal darkness after brief flashes of light and enhances the amplitude of responses to higher-frequency stimuli. By accelerating the resupply of vesicles to the ribbon, CaM extends the temporal range of synaptic transmission, allowing cones to transmit higher-frequency visual information to downstream neurons. Thus, the ability of the visual system to encode time-varying stimuli is shaped by the dynamics of vesicle replenishment at photoreceptor synaptic ribbons.
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Affiliation(s)
- Matthew J Van Hook
- Department of Ophthalmology and Visual Sciences and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
| | - Caitlyn M Parmelee
- Department of Mathematics, University of Nebraska-Lincoln, Lincoln, NE 68588
| | - Minghui Chen
- Department of Ophthalmology and Visual Sciences and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198 Department of Ophthalmology and Visual Sciences and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
| | - Karlene M Cork
- Department of Ophthalmology and Visual Sciences and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198 Department of Ophthalmology and Visual Sciences and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
| | - Carina Curto
- Department of Mathematics, University of Nebraska-Lincoln, Lincoln, NE 68588 Department of Mathematics, The Pennsylvania State University, University Park, State College, PA 16802
| | - Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198 Department of Ophthalmology and Visual Sciences and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198
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17
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Knodel MM, Geiger R, Ge L, Bucher D, Grillo A, Wittum G, Schuster CM, Queisser G. Synaptic bouton properties are tuned to best fit the prevailing firing pattern. Front Comput Neurosci 2014; 8:101. [PMID: 25249970 PMCID: PMC4158995 DOI: 10.3389/fncom.2014.00101] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 08/07/2014] [Indexed: 11/25/2022] Open
Abstract
The morphology of presynaptic specializations can vary greatly ranging from classical single-release-site boutons in the central nervous system to boutons of various sizes harboring multiple vesicle release sites. Multi-release-site boutons can be found in several neural contexts, for example at the neuromuscular junction (NMJ) of body wall muscles of Drosophila larvae. These NMJs are built by two motor neurons forming two types of glutamatergic multi-release-site boutons with two typical diameters. However, it is unknown why these distinct nerve terminal configurations are used on the same postsynaptic muscle fiber. To systematically dissect the biophysical properties of these boutons we developed a full three-dimensional model of such boutons, their release sites and transmitter-harboring vesicles and analyzed the local vesicle dynamics of various configurations during stimulation. Here we show that the rate of transmission of a bouton is primarily limited by diffusion-based vesicle movements and that the probability of vesicle release and the size of a bouton affect bouton-performance in distinct temporal domains allowing for an optimal transmission of the neural signals at different time scales. A comparison of our in silico simulations with in vivo recordings of the natural motor pattern of both neurons revealed that the bouton properties resemble a well-tuned cooperation of the parameters release probability and bouton size, enabling a reliable transmission of the prevailing firing-pattern at diffusion-limited boutons. Our findings indicate that the prevailing firing-pattern of a neuron may determine the physiological and morphological parameters required for its synaptic terminals.
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Affiliation(s)
- Markus M Knodel
- Bernstein Group Detailed Modeling of Signal Processing in Neurons, University of Heidelberg and University of Frankfurt Heidelberg/Frankfurt, Germany ; Department of Simulation and Modeling, Goethe Center for Scientific Computing, University of Frankfurt Frankfurt, Germany
| | - Romina Geiger
- Bernstein Center for Computational Neuroscience Heidelberg-Mannheim Heidelberg/Mannheim, Germany ; Department of Neurobiology, Interdisciplinary Center for Neurosciences, University of Heidelberg Heidelberg, Germany
| | - Lihao Ge
- Bernstein Center for Computational Neuroscience Heidelberg-Mannheim Heidelberg/Mannheim, Germany ; Department of Neurobiology, Interdisciplinary Center for Neurosciences, University of Heidelberg Heidelberg, Germany
| | - Daniel Bucher
- Bernstein Group Detailed Modeling of Signal Processing in Neurons, University of Heidelberg and University of Frankfurt Heidelberg/Frankfurt, Germany ; Department of Neurobiology, Interdisciplinary Center for Neurosciences, University of Heidelberg Heidelberg, Germany ; Development Unit, European Molecular Biology Laboratory Heidelberg, Germany
| | - Alfio Grillo
- Department of Simulation and Modeling, Goethe Center for Scientific Computing, University of Frankfurt Frankfurt, Germany ; Department of Mathematical Sciences, Polythecnic of Turin Turin, Italy
| | - Gabriel Wittum
- Bernstein Group Detailed Modeling of Signal Processing in Neurons, University of Heidelberg and University of Frankfurt Heidelberg/Frankfurt, Germany ; Department of Simulation and Modeling, Goethe Center for Scientific Computing, University of Frankfurt Frankfurt, Germany
| | - Christoph M Schuster
- Bernstein Group Detailed Modeling of Signal Processing in Neurons, University of Heidelberg and University of Frankfurt Heidelberg/Frankfurt, Germany ; Bernstein Center for Computational Neuroscience Heidelberg-Mannheim Heidelberg/Mannheim, Germany ; Department of Neurobiology, Interdisciplinary Center for Neurosciences, University of Heidelberg Heidelberg, Germany
| | - Gillian Queisser
- Bernstein Group Detailed Modeling of Signal Processing in Neurons, University of Heidelberg and University of Frankfurt Heidelberg/Frankfurt, Germany ; Bernstein Center for Computational Neuroscience Heidelberg-Mannheim Heidelberg/Mannheim, Germany ; Department of Computational Neuroscience, Goethe Center for Scientific Computing, University of Frankfurt Frankfurt, Germany
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18
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Vasil’ev AN, Kulish AV. Influence of mediator diffusion on trigger mode of a synapse. Biophysics (Nagoya-shi) 2014. [DOI: 10.1134/s0006350914020262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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19
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Abstract
Synaptic vesicle recycling is one of the best-studied cellular pathways. Many of the proteins involved are known, and their interactions are becoming increasingly clear. However, as for many other pathways, it is still difficult to understand synaptic vesicle recycling as a whole. While it is generally possible to point out how synaptic reactions take place, it is not always easy to understand what triggers or controls them. Also, it is often difficult to understand how the availability of the reaction partners is controlled: how the reaction partners manage to find each other in the right place, at the right time. I present here an overview of synaptic vesicle recycling, discussing the mechanisms that trigger different reactions, and those that ensure the availability of reaction partners. A central argument is that synaptic vesicles bind soluble cofactor proteins, with low affinity, and thus control their availability in the synapse, forming a buffer for cofactor proteins. The availability of cofactor proteins, in turn, regulates the different synaptic reactions. Similar mechanisms, in which one of the reaction partners buffers another, may apply to many other processes, from the biogenesis to the degradation of the synaptic vesicle.
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Affiliation(s)
- Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen European Neuroscience Institute, Göttingen, Germany
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20
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Bui L, Glavinović MI. Temperature dependence of vesicular dynamics at excitatory synapses of rat hippocampus. Cogn Neurodyn 2014; 8:277-86. [PMID: 25009670 DOI: 10.1007/s11571-014-9283-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 01/27/2014] [Accepted: 02/09/2014] [Indexed: 10/25/2022] Open
Abstract
How vesicular dynamics parameters depend on temperature and how temperature affects the parameter change during prolonged high frequency stimulation was determined by fitting a model of vesicular storage and release to the amplitudes of the excitatory post-synaptic currents (EPSC) recorded from CA1 neurons in rat hippocampal slices. The temperature ranged from low (13 °C) to higher and more physiological temperature (34 °C). Fitting the model of vesicular storage and release to the EPSC amplitudes during a single pair of brief high-low frequency stimulation trains yields the estimates of all parameters of the vesicular dynamics, and with good precision. Both fractional release and replenishment rate decrease as the temperature rises. Change of the underlying 'basic' parameters (release coupling, replenishment coupling and readily releasable pool size), which the model-fitting also yields is complex. The replenishment coupling between the readily releasable pool (RRP) and resting pool increases with temperature (which renders the replenishment rate higher), but this is more than counterbalanced by greater RRP size (which renders the replenishment rate lower). Finally, during long, high frequency patterned stimulation that leads to significant synaptic depression, the replenishment rate decreases markedly and rapidly at low temperatures (<22 °C), but at high temperatures (>28 °C) the replenishment rate rises with stimulation, making synapses better able to maintain synaptic efficacy.
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Affiliation(s)
- Loc Bui
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, PQ H3G 1Y6 Canada
| | - Mladen I Glavinović
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, PQ H3G 1Y6 Canada
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21
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Bui L, Glavinović MI. Recovery of vesicular storage and release parameters after high frequency stimulation in rat hippocampus. Cogn Neurodyn 2014; 7:311-23. [PMID: 24427207 DOI: 10.1007/s11571-012-9240-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 12/15/2012] [Accepted: 12/25/2012] [Indexed: 10/27/2022] Open
Abstract
The replenishment rates estimated from the recovery of synaptic efficacy following synaptic depression are known to be widely scattered. Given the importance of the replenishment during stimulation, especially if it is prolonged, it is important to better understand what influences the recovery of the synaptic efficacy following stimulation. We fit a two-pool model of vesicular secretion to the changes of the excitatory post-synaptic currents recorded in CA1 neurons of rat hippocampal slices to determine how the model parameters change during, and following, long stimulation. The replenishment rate at the end of stimulation inducing synaptic depression differs greatly from that at the beginning of stimulation. It decreases progressively and rapidly (by ~75 % and with a time constant of <10 s) during stimulation, and this is followed by a similarly fast recovery (time constant of ~10 s), but to a steady-state that is approximately twice as large as its pre-stimulation value. Both [Ca(++)]o and the duration of long stimulation influence the recovery of the replenishment rate. Its new steady-state is significantly higher, if either [Ca(++)]o is higher or stimulation longer, but the recovery of the replenishment rate becomes clearly slower if [Ca(++)]o is higher, and faster if stimulation is longer. Many factors thus influence the recovery of the replenishment rate and of the synaptic efficacy, but the stimulation induced [Ca(++)]i accumulation cannot explain the change of the replenishment rate during recovery. Finally, okadaic acid, which speeds up vesicular trafficking, does not alter the recovery of the replenishment rate. The vesicular replenishment of the RRP following stimulation is thus not likely to be associated with significant vesicular movement.
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Affiliation(s)
- Loc Bui
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, PQ H3G 1Y6 Canada
| | - Mladen I Glavinović
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, PQ H3G 1Y6 Canada
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22
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Bui L, Glavinović MI. Is replenishment of the readily releasable pool associated with vesicular movement? Cogn Neurodyn 2013; 8:99-110. [PMID: 24624230 DOI: 10.1007/s11571-013-9264-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 06/19/2013] [Accepted: 07/23/2013] [Indexed: 12/30/2022] Open
Abstract
At the excitatory synapse of rat hippocampus the short-term synaptic depression observed during long high-frequency stimulation is associated with slower replenishment of the readily-releasable pool. Given that the replenishment rate is also not [Ca(++)]o sensitive this puts into question a widely held notion that the vesicles-constrained by the cytoskeleton and rendered free from such constraints by Ca(++) entry that renders them more mobile-are important in the replenishment of the readily-releasable pool. This raises a question-Is vesicular replenishment of the readily releasable pool associated with significant movement? To answer this question we evaluated how okadaic acid and staurosporine (compounds known to affect vesicular mobility) influence the replenishment rate. We used patterned stimulation on the Schaffer collateral fiber pathway and recorded the excitatory post-synaptic currents (EPSCs) from rat CA1 neurons, in the absence and presence of these drugs. The parameters of a circuit model with two vesicular pools were estimated by minimizing the squared difference between the ESPC amplitudes and simulated model output. [Ca(2+)]o did not influence the progressive decrease of the replenishment rate during long, high frequency stimulation. Okadaic acid did not significantly affect any parameters of the vesicular storage and release system, including the replenishment rate. Staurosporine reduced the replenishment coupling, but not the replenishment rate, and this is owing to the fact that it also reduces the ability of the readily releasable pool to contain quanta. Moreover, these compounds were ineffective in influencing how the replenishment rate decreases during long, high frequency stimulation. In conclusion at the excitatory synapses of rat hippocampus the replenishment of the readily releasable pool does not appear to be associated with a significant vesicular movement, and during long high frequency stimulation [Ca(++)]o does not influence the progressive decrease of vesicular replenishment.
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Affiliation(s)
- Loc Bui
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, H3G 1Y6 Canada
| | - Mladen I Glavinović
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, H3G 1Y6 Canada
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23
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Abstract
Low-frequency depression (LFD) of transmitter release occurs at phasic synapses with stimulation at 0.2 Hz in both isolated crayfish (Procambarus clarkii) neuromuscular junction (NMJ) preparations and in intact animals. LFD is regulated by presynaptic activity of the Ca(2+)-dependent phosphatase calcineurin (Silverman-Gavrila and Charlton, 2009). Since the fast Ca(2+) chelator BAPTA-AM inhibits LFD but the slow chelator EGTA-AM does not, the Ca(2+) sensor for LFD may be close to a Ca(2+) source at active zones. Calcineurin can be activated by the Ca(2+)-activated protease calpain, and immunostaining showed that both proteins are present at nerve terminals. Three calpain inhibitors, calpain inhibitor I, MDL-28170, and PD150606, but not the control compound PD145305, inhibit LFD both in the intact animal as shown by electromyograms and by intracellular recordings at neuromuscular junctions. Analysis of mini-EPSPs indicated that these inhibitors had minimal postsynaptic effects. Proteolytic activity in CNS extract, detected by a fluorescent calpain substrate, was modulated by Ca(2+) and calpain inhibitors. Western blot analysis of CNS extract showed that proteolysis of calcineurin to a fragment consistent with the constitutively active form required Ca(2+) and was blocked by calpain inhibitors. Inhibition of LFD by calpain inhibition blocks the reduction in phosphoactin and the depolymerization of tubulin that normally occurs in LFD, probably by blocking the dephosphorylation of cytoskeletal proteins by calcineurin. In contrast, high-frequency depression does not involve protein phosphorylation- or calpain-dependent mechanisms. LFD may involve a specific pathway in which local Ca(2+) signaling activates presynaptic calpain and calcineurin at active zones and causes changes of tubulin cytoskeleton.
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24
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Abstract
Synaptic vesicles release neurotransmitter at chemical synapses, thus initiating the flow of information in neural networks. To achieve this, vesicles undergo a dynamic cycle of fusion and retrieval to maintain the structural and functional integrity of the presynaptic terminals in which they reside. Moreover, compelling evidence indicates these vesicles differ in their availability for release and mobilization in response to stimuli, prompting classification into at least three different functional pools. Ongoing studies of the molecular and cellular bases for this heterogeneity attempt to link structure to physiology and clarify how regulation of vesicle pools influences synaptic strength and presynaptic plasticity. We discuss prevailing perspectives on vesicle pools, the role they play in shaping synaptic transmission, and the open questions that challenge current understanding.
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Affiliation(s)
- AbdulRasheed A Alabi
- Department of Molecular and Cellular Physiology, Stanford Institute for Neuro-Innovation and Translational Neurosciences, Stanford Medical School, Stanford, California 94305, USA
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25
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Seabrooke S, Stewart BA. Synaptic transmission and plasticity are modulated by nonmuscle myosin II at the neuromuscular junction of Drosophila. J Neurophysiol 2011; 105:1966-76. [PMID: 21325687 DOI: 10.1152/jn.00718.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The synaptic vesicle population in a nerve terminal is traditionally divided into subpopulations according to physiological criteria; the readily releasable pool (RRP), the recycling pool, and the reserve pool. It is recognized that the RRP subserves synaptic transmission evoked by low-frequency neural activity and that the recycling and reserve populations are called on to supply vesicles as neural activity increases. Here we investigated the contribution of nonmuscle myosin II (NMMII) to synaptic transmission with emphasis on the role a motor protein could play in the supply of vesicles. We used Drosophila genetics to manipulate NMMII and assessed synaptic transmission at the larval neuromuscular junction. We observed a positive correlation between synaptic strength at low-frequency stimulation and NMMII expression: reducing NMMII reduced the evoked response, while increasing NMMII increased the evoked response. Further, we found that NMMII contributed to the spontaneous release of vesicles differentially from evoked release, suggesting differential contribution to these two release mechanisms. By measuring synaptic responses under conditions of differing external calcium concentration in saline, we found that NMMII is important for normal synaptic transmission under high-frequency stimulation. This research identifies diverse functions for NMMII in synaptic transmission and suggests that this motor protein is an active contributor to the physiology of synaptic vesicle recruitment.
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Affiliation(s)
- Sara Seabrooke
- Department of Biology, University of Toronto, Mississauga, Ontario, Canada
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26
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Siksou L, Triller A, Marty S. Ultrastructural organization of presynaptic terminals. Curr Opin Neurobiol 2011; 21:261-8. [PMID: 21247753 DOI: 10.1016/j.conb.2010.12.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 12/17/2010] [Indexed: 01/03/2023]
Abstract
In response to calcium influx, synaptic vesicles fuse very rapidly with the plasma membrane to release their neurotransmitter content. An important mechanism for sustained release includes the formation of new vesicles by local endocytosis. How synaptic vesicles are trafficked from the sites of endocytosis to the sites of release and how they are maintained at the release sites remain poorly understood. Recent studies using fast freezing immobilization and electron tomography have led to insights on the ultrastructural organization of presynaptic boutons and how these structural elements may maintain synaptic vesicles and organize their exocytosis at particular areas of the plasma membrane.
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Affiliation(s)
- Léa Siksou
- Institute of Biology of the Ecole Normale Supérieure, 46 rue d'Ulm, 75005 Paris, France
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27
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Golgi in retrospect: a historiographic examination of contextual influence in tracing the constructs of neuronal organization. ACTA ACUST UNITED AC 2011; 66:68-74. [PMID: 20637231 DOI: 10.1016/j.brainresrev.2010.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 06/30/2010] [Accepted: 07/07/2010] [Indexed: 11/21/2022]
Abstract
The concepts underlying the connectivity of neurons and the dynamics of interaction required to explain information processing have undergone significant change over the past century. A re-examination of the evolution of the modern view in historical context reveals that rules for connectivity have changed in a manner that might be expected from critical analysis enabled by technical advance. A retrospective examination of some germane issues that moved Camillo Golgi to question the widely held dogma of his era reveals network principles that could not have been recognized a century ago. The currently evolving rules of cellular discontinuity and interaction have proven sufficiently complex to justify the arguments of critical skepticism that sustain scientific progress.
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28
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High- and low-mobility stages in the synaptic vesicle cycle. Biophys J 2010; 99:675-84. [PMID: 20643088 DOI: 10.1016/j.bpj.2010.04.054] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 04/12/2010] [Accepted: 04/20/2010] [Indexed: 11/24/2022] Open
Abstract
Synaptic vesicles need to be mobile to reach their release sites during synaptic activity. We investigated vesicle mobility throughout the synaptic vesicle cycle using both conventional and subdiffraction-resolution stimulated emission depletion fluorescence microscopy. Vesicle tracking revealed that recently endocytosed synaptic vesicles are highly mobile for a substantial time period after endocytosis. They later undergo a maturation process and integrate into vesicle clusters where they exhibit little mobility. Despite the differences in mobility, both recently endocytosed and mature vesicles are exchanged between synapses. Electrical stimulation does not seem to affect the mobility of the two types of vesicles. After exocytosis, the vesicle material is mobile in the plasma membrane, although the movement appears to be somewhat limited. Increasing the proportion of fused vesicles (by stimulating exocytosis while simultaneously blocking endocytosis) leads to substantially higher mobility. We conclude that both high- and low-mobility states are characteristic of synaptic vesicle movement.
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29
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Denker A, Rizzoli SO. Synaptic vesicle pools: an update. Front Synaptic Neurosci 2010; 2:135. [PMID: 21423521 PMCID: PMC3059705 DOI: 10.3389/fnsyn.2010.00135] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2010] [Accepted: 08/02/2010] [Indexed: 12/04/2022] Open
Abstract
During the last few decades synaptic vesicles have been assigned to a variety of functional and morphological classes or “pools”. We have argued in the past (Rizzoli and Betz, 2005) that synaptic activity in several preparations is accounted for by the function of three vesicle pools: the readily releasable pool (docked at active zones and ready to go upon stimulation), the recycling pool (scattered throughout the nerve terminals and recycling upon moderate stimulation), and finally the reserve pool (occupying most of the vesicle clusters and only recycling upon strong stimulation). We discuss here the advancements in the vesicle pool field which took place in the ensuing years, focusing on the behavior of different pools under both strong stimulation and physiological activity. Several new findings have enhanced the three-pool model, with, for example, the disparity between recycling and reserve vesicles being underlined by the observation that the former are mobile, while the latter are “fixed”. Finally, a number of altogether new concepts have also evolved such as the current controversy on the identity of the spontaneously recycling vesicle pool.
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Affiliation(s)
- Annette Denker
- European Neuroscience Institute, DFG Center for Molecular Physiology of the Brain Göttingen, Germany
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30
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Staras K, Branco T. Sharing vesicles between central presynaptic terminals: implications for synaptic function. Front Synaptic Neurosci 2010; 2:20. [PMID: 21423506 PMCID: PMC3059672 DOI: 10.3389/fnsyn.2010.00020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 05/27/2010] [Indexed: 11/13/2022] Open
Abstract
Presynaptic terminals in hippocampal neurons house functionally distinct vesicle pools, the size, structure and biochemical features of which are major determinants of presynaptic strength and performance. In classical models of synaptic function these vesicle pools are synapse-specific, but accumulating evidence is now demonstrating that some vesicles are laterally mobile along axons and readily shared in a functional manner across adjacent terminals. In effect then, these mobile vesicles represent a further class of synapse-spanning vesicle pool, or "superpool". Here we outline the characteristics of this additional pool type, discussing its structural organization within axons and presynaptic terminals as well as its relationship with conventional vesicle pools. We draw comparisons between extrasynaptic vesicle dynamics and the growing literature on extrasynaptic mobility of non-vesicular synaptic elements which, taken together, raise important questions about the operational independence of adjacent release sites. We also examine the functional implications of lateral vesicle sharing, from the notion that extrasynaptic vesicles can contribute to the release capabilities of individual terminals, to its potential role as a substrate for facilitating changes in synaptic weight as a basis for plasticity.
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Affiliation(s)
- Kevin Staras
- School of Life Sciences, University of Sussex Brighton, UK
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Seabrooke S, Qiu X, Stewart BA. Nonmuscle Myosin II helps regulate synaptic vesicle mobility at the Drosophila neuromuscular junction. BMC Neurosci 2010; 11:37. [PMID: 20233422 PMCID: PMC2853426 DOI: 10.1186/1471-2202-11-37] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 03/16/2010] [Indexed: 11/22/2022] Open
Abstract
Background Although the mechanistic details of the vesicle transport process from the cell body to the nerve terminal are well described, the mechanisms underlying vesicle traffic within nerve terminal boutons is relatively unknown. The actin cytoskeleton has been implicated but exactly how actin or actin-binding proteins participate in vesicle movement is not clear. Results In the present study we have identified Nonmuscle Myosin II as a candidate molecule important for synaptic vesicle traffic within Drosophila larval neuromuscular boutons. Nonmuscle Myosin II was found to be localized at the Drosophila larval neuromuscular junction; genetics and pharmacology combined with the time-lapse imaging technique FRAP were used to reveal a contribution of Nonmuscle Myosin II to synaptic vesicle movement. FRAP analysis showed that vesicle dynamics were highly dependent on the expression level of Nonmuscle Myosin II. Conclusion Our results provide evidence that Nonmuscle Myosin II is present presynaptically, is important for synaptic vesicle mobility and suggests a role for Nonmuscle Myosin II in shuttling vesicles at the Drosophila neuromuscular junction. This work begins to reveal the process by which synaptic vesicles traverse within the bouton.
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Affiliation(s)
- Sara Seabrooke
- Department of Biology, University of Toronto, Mississauga, ON L5L 1C6, Canada
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Fernández-Busnadiego R, Zuber B, Maurer UE, Cyrklaff M, Baumeister W, Lucic V. Quantitative analysis of the native presynaptic cytomatrix by cryoelectron tomography. ACTA ACUST UNITED AC 2010; 188:145-56. [PMID: 20065095 PMCID: PMC2812849 DOI: 10.1083/jcb.200908082] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The filamentous structures that tether exocytic vesicles to the plasma membrane in the active zone are rearranged in response to synaptic stimulation. The presynaptic terminal contains a complex network of filaments whose precise organization and functions are not yet understood. The cryoelectron tomography experiments reported in this study indicate that these structures play a prominent role in synaptic vesicle release. Docked synaptic vesicles did not make membrane to membrane contact with the active zone but were instead linked to it by tethers of different length. Our observations are consistent with an exocytosis model in which vesicles are first anchored by long (>5 nm) tethers that give way to multiple short tethers once vesicles enter the readily releasable pool. The formation of short tethers was inhibited by tetanus toxin, indicating that it depends on soluble N-ethyl-maleimide sensitive fusion protein attachment protein receptor complex assembly. Vesicles were extensively interlinked via a set of connectors that underwent profound rearrangements upon synaptic stimulation and okadaic acid treatment, suggesting a role of these connectors in synaptic vesicle mobilization and neurotransmitter release.
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Affiliation(s)
- Rubén Fernández-Busnadiego
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, D-82152 Martinsried, Germany
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SMN, profilin IIa and plastin 3: A link between the deregulation of actin dynamics and SMA pathogenesis. Mol Cell Neurosci 2009; 42:66-74. [DOI: 10.1016/j.mcn.2009.05.009] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 05/20/2009] [Accepted: 05/26/2009] [Indexed: 11/21/2022] Open
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Short term memory may be the depletion of the readily releasable pool of presynaptic neurotransmitter vesicles of a metastable long term memory trace pattern. Cogn Neurodyn 2009; 3:263-9. [PMID: 19484378 DOI: 10.1007/s11571-009-9085-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2008] [Revised: 05/05/2009] [Accepted: 05/05/2009] [Indexed: 10/20/2022] Open
Abstract
The Tagging/Retagging model of short term memory was introduced earlier (Tarnow in Cogn Neurodyn 2(4):347-353, 2008) to explain the linear relationship between response time and correct response probability for word recall and recognition: At the initial stimulus presentation the words displayed tag the corresponding long term memory locations. The tagging process is linear in time and takes about one second to reach a tagging level of 100%. After stimulus presentation the tagging level decays logarithmically with time to 50% after 14 s and to 20% after 220 s. If a probe word is reintroduced the tagging level has to return to 100% for the word to be properly identified, which leads to a delay in response time. This delay is proportional to the tagging loss. The tagging level is directly related to the probability of correct word recall and recognition. Evidence presented suggests that the tagging level is the level of depletion of the Readily Releasable Pool (RRP) of neurotransmitter vesicles at presynaptic terminals. The evidence includes the initial linear relationship between tagging level and time as well as the subsequent logarithmic decay of the tagging level. The activation of a short term memory may thus be the depletion of RRP (exocytosis) and short term memory decay may be the ensuing recycling of the neurotransmitter vesicles (endocytosis). The pattern of depleted presynaptic terminals corresponds to the long term memory trace.
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Abstract
Transmitter release at high probability phasic synapses of crayfish neuromuscular junctions depresses by over 50% in 60 min when stimulated at 0.2 Hz. Inhibition of the protein phosphatase calcineurin by intracellular pre-synaptic injection of autoinhibitory peptide inhibited low-frequency depression (LFD) and resulted in facilitation of transmitter release. Since this inhibitor had no major effects when injected into the post-synaptic cell, only pre-synaptic calcineurin activity is necessary for LFD. To examine changes in phosphoproteins during LFD we performed a phosphoproteomic screen on proteins extracted from motor axons and nerve terminals after LFD induction or treatment with various drugs that affect kinase and phosphatase activity. Proteins separated by PAGE were stained with phospho-specific/total protein ratio stains (Pro-Q Diamond/SYPRO Ruby) to identify protein bands for analysis by mass spectrometry. Phosphorylation of actin and tubulin decreased during LFD, but increased when calcineurin was blocked. Tubulin and phosphoactin immunoreactivity in pre-synaptic terminals were also reduced after LFD. The actin depolymerizing drugs cytochalasin and latrunculin and the microtubule stabilizer taxol inhibited LFD. Therefore, dephosphorylation of pre-synaptic actin and tubulin and consequent changes in the cytoskeleton may regulate LFD. LFD is unlike long-term depression found in mammalian synapses because the latter requires in most instances post-synaptic calcineurin activity.Thus, this simpler invertebrate synapse discloses a novel pre-synaptic depression mechanism.
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The synaptic vesicle cluster: A source of endocytic proteins during neurotransmitter release. Neuroscience 2009; 158:204-10. [DOI: 10.1016/j.neuroscience.2008.03.035] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/17/2008] [Accepted: 03/18/2008] [Indexed: 12/11/2022]
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Abstract
Information processing in the nervous system relies on properly localized and organized synaptic structures at the correct locations. The formation of synapses is a long and intricate process involving multiple interrelated steps. Decades of research have identified a large number of molecular components of the presynaptic compartment. In addition to neurotransmitter-containing synaptic vesicles, presynaptic terminals are defined by cytoskeletal and membrane specializations that allow highly regulated exo- and endocytosis of synaptic vesicles and that maintain precise registration with postsynaptic targets. Functional studies at multiple levels have revealed complex interactions between the transport of vesicular intermediates, the presynaptic cytoskeleton, growth cone navigation, and synaptic targets. With the advent of finer anatomical, physiological, and molecular tools, great insights have been gained toward the mechanistic dissection of functionally redundant processes controlling the specificity and dynamics of synapses. This review highlights the recent findings pertaining to the cellular and molecular regulation of presynaptic differentiation.
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Affiliation(s)
- Yishi Jin
- Division of Biological Sciences, Section of Neurobiology, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093, USA.
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38
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Cingolani LA, Goda Y. Actin in action: the interplay between the actin cytoskeleton and synaptic efficacy. Nat Rev Neurosci 2008; 9:344-56. [PMID: 18425089 DOI: 10.1038/nrn2373] [Citation(s) in RCA: 581] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Synapse regulation exploits the capacity of actin to function as a stable structural component or as a dynamic filament. Beyond its well-appreciated role in eliciting visible morphological changes at the synapse, the emerging picture points to an active contribution of actin to the modulation of the efficacy of pre- and postsynaptic terminals. Moreover, by engaging distinct pools of actin and divergent signalling pathways, actin-dependent morphological plasticity could be uncoupled from modulation of synaptic strength. The aim of this Review is to highlight some of the recent progress in elucidating the role of the actin cytoskeleton in synaptic function.
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Affiliation(s)
- Lorenzo A Cingolani
- MRC Laboratory for Molecular Cell Biology and MRC Cell Biology Unit, University College London, Gower Street, London, WC1E 6BT, UK
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Santos MS, Li H, Voglmaier SM. Synaptic vesicle protein trafficking at the glutamate synapse. Neuroscience 2008; 158:189-203. [PMID: 18472224 DOI: 10.1016/j.neuroscience.2008.03.029] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 02/25/2008] [Accepted: 03/08/2008] [Indexed: 11/27/2022]
Abstract
Expression of the integral and associated proteins of synaptic vesicles is subject to regulation over time, by region, and in response to activity. The process by which changes in protein levels and isoforms result in different properties of neurotransmitter release involves protein trafficking to the synaptic vesicle. How newly synthesized proteins are incorporated into synaptic vesicles at the presynaptic bouton is poorly understood. During synaptogenesis, synaptic vesicle proteins sort through the secretory pathway and are transported down the axon in precursor vesicles that undergo maturation to form synaptic vesicles. Changes in protein content of synaptic vesicles could involve the formation of new vesicles that either mix with the previous complement of vesicles or replace them, presumably by their degradation or inactivation. Alternatively, new proteins could individually incorporate into existing synaptic vesicles, changing their functional properties. Glutamatergic vesicles likely express many of the same integral membrane proteins and share certain common mechanisms of biogenesis, recycling, and degradation with other synaptic vesicles. However, glutamatergic vesicles are defined by their ability to package glutamate for release, a property conferred by the expression of a vesicular glutamate transporter (VGLUT). VGLUTs are subject to regional, developmental, and activity-dependent changes in expression. In addition, VGLUT isoforms differ in their trafficking, which may target them to different pathways during biogenesis or after recycling, which may in turn sort them to different vesicle pools. Emerging data indicate that differences in the association of VGLUTs and other synaptic vesicle proteins with endocytic adaptors may influence their trafficking. These observations indicate that independent regulation of synaptic vesicle protein trafficking has the potential to influence synaptic vesicle protein composition, the maintenance of synaptic vesicle pools, and the release of glutamate in response to changing physiological requirements.
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Affiliation(s)
- M S Santos
- Department of Psychiatry, University of California School of Medicine, 401 Parnassus Avenue, LPPI-A101, San Francisco, CA 94143-0984, USA
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40
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Westphal V, Rizzoli SO, Lauterbach MA, Kamin D, Jahn R, Hell SW. Video-Rate Far-Field Optical Nanoscopy Dissects Synaptic Vesicle Movement. Science 2008; 320:246-9. [DOI: 10.1126/science.1154228] [Citation(s) in RCA: 626] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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41
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Abstract
We measured synaptic vesicle mobility using fluorescence recovery after photobleaching of FM 1-43 [N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide] stained mouse motor nerve terminals obtained from wild-type (WT) and synapsin triple knock-out (TKO) mice at room temperature and physiological temperature. Vesicles were mobile in resting terminals at physiological temperature but virtually immobile at room temperature. Mobility was increased at both temperatures by blocking phosphatases with okadaic acid, decreased at physiological temperature by blocking kinases with staurosporine, and unaffected by disrupting actin filaments with latrunculin A or reducing intracellular calcium concentration with BAPTA-AM. Synapsin TKO mice showed reduced numbers of synaptic vesicles and reduced FM 1-43 staining intensity. Synaptic transmission, however, was indistinguishable from WT, as was synaptic vesicle mobility under all conditions tested. Thus, in TKO mice, and perhaps WT mice, a phospho-protein different from synapsin but otherwise of unknown identity is the primary regulator of synaptic vesicle mobility.
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Suyama S, Hikima T, Sakagami H, Ishizuka T, Yawo H. Synaptic vesicle dynamics in the mossy fiber-CA3 presynaptic terminals of mouse hippocampus. Neurosci Res 2007; 59:481-90. [PMID: 17933408 DOI: 10.1016/j.neures.2007.08.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 08/15/2007] [Accepted: 08/31/2007] [Indexed: 11/17/2022]
Abstract
The mossy fiber (MF)-CA3 synapse in the hippocampus is unique in the CNS because of its wide dynamic range of transmitter release during short- and long-term plasticity. The presynaptic mechanisms underlying the fidelity of transmission were investigated for the MF-CA3 synapses. The relative size of readily releasable pool (RRP) of vesicles was estimated by counting the number of docked vesicles at an active zone (AZ) on the transmission electron microscopy (TEM) image. The size of the releasable pool and the exo-endocytosis kinetics were directly measured from individual large MF boutons in hippocampal slices of transgenic mice that selectively express synaptopHluorin (SpH), a pH-sensitive GFP fused to the lumenal aspect of one of the vesicular membrane proteins, VAMP-2, in these boutons. Here we found (1) there are distinct two vesicle pools, the resting pool which is resistant to exocytosis, and the releasable pool, (2) the initially docked vesicles are easily depleted and the RRP is maintained by refilling from the reserve subpopulation of releasable pool ("reserve" releasable pool), and (3) the contribution of rapid reuse of recycled vesicles is relatively small. Therefore, the fidelity of transmission is suggested to be ensured by the rapid refilling rate of RRP.
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Affiliation(s)
- Shigetomo Suyama
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, Tochigi, Japan
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43
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Siksou L, Rostaing P, Lechaire JP, Boudier T, Ohtsuka T, Fejtová A, Kao HT, Greengard P, Gundelfinger ED, Triller A, Marty S. Three-dimensional architecture of presynaptic terminal cytomatrix. J Neurosci 2007; 27:6868-77. [PMID: 17596435 PMCID: PMC6672225 DOI: 10.1523/jneurosci.1773-07.2007] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Presynaptic terminals are specialized for mediating rapid fusion of synaptic vesicles (SVs) after calcium influx. The regulated trafficking of SVs likely results from a highly organized cytomatrix. How this cytomatrix links SVs, maintains them near the active zones (AZs) of release, and organizes docked SVs at the release sites is not fully understood. To analyze the three-dimensional (3D) architecture of the presynaptic cytomatrix, electron tomography of presynaptic terminals contacting spines was performed in the stratum radiatum of the rat hippocampal CA1 area. To preserve the cytomatrix, hippocampal slices were immobilized using high-pressure freezing, followed by cryosubstitution and embedding. SVs are surrounded by a dense network of filaments. A given vesicle is connected to approximately 1.5 neighboring ones. SVs at the periphery of this network are also linked to the plasma membrane, by longer filaments. More of these filaments are found at the AZ. At the AZ, docked SVs are grouped around presynaptic densities. Filaments with adjacent SVs emerge from these densities. Immunogold localizations revealed that synapsin is located in the presynaptic bouton, whereas Bassoon and CAST (ERC2) are at focal points next to the AZ. In synapsin triple knock-out mice, the number of SVs is reduced by 63%, but the size of the boutons is reduced by only 18%, and the mean distance of SVs to the AZ is unchanged. This 3D analysis reveals the morphological constraints exerted by the presynaptic molecular scaffold. SVs are tightly interconnected in the axonal bouton, and this network is preferentially connected to the AZ.
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Affiliation(s)
- Léa Siksou
- Inserm U789, Ecole Normale Supérieure, 75005 Paris, France
| | | | - Jean-Pierre Lechaire
- Service de CryoMicroscopie Electronique, Institut Fédératif de Recherche Biologie Intégrative 83 Centre National de la Recherche Scientifique, Université Pierre et Marie Curie, 75252 Paris cedex 05, France
| | - Thomas Boudier
- Imagerie Intégrative, Inserm U759, Institut Curie, Bâtiment 112, Centre Universitaire Orsay, 91405 Orsay cedex, France
| | - Toshihisa Ohtsuka
- Department of Clinical and Molecular Pathology, Faculty of Medicine/Graduate School of Medicine, University of Toyama, Toyama 930-0194, Japan
| | - Anna Fejtová
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | - Hung-Teh Kao
- Department of Psychiatry, New York University School of Medicine, and Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962, and
| | - Paul Greengard
- Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021
| | - Eckart D. Gundelfinger
- Department of Neurochemistry and Molecular Biology, Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany
| | | | - Serge Marty
- Inserm U789, Ecole Normale Supérieure, 75005 Paris, France
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Staras K. Share and share alike: trading of presynaptic elements between central synapses. Trends Neurosci 2007; 30:292-8. [PMID: 17467066 DOI: 10.1016/j.tins.2007.04.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 03/20/2007] [Accepted: 04/18/2007] [Indexed: 11/21/2022]
Abstract
Central presynaptic terminals harbour synaptic vesicles (SVs) and synapse-specific proteins necessary for neurotransmission. Classically, these elements were thought to reside more or less stably at individual mature synapses, giving rise to the idea that each terminal was essentially an independent functional unit. However, emerging evidence from fluorescence imaging studies in hippocampal cultured neurons is now challenging this view, suggesting that neighbouring synapses along axons share vesicles, and also other synaptic elements, at high levels. This raises the possibility that control of import and export might be an important regulatory target for the maintenance of release sites, modulation of synaptic efficacy and formation of new synaptic contacts. Here, temporal synaptic stability and the functional consequences for presynaptic operation will be considered.
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Affiliation(s)
- Kevin Staras
- MRC Laboratory for Molecular Cell Biology and Cell Biology Unit, University College London, London, UK.
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45
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Yeung C, Shtrahman M, Wu XL. Stick-and-diffuse and caged diffusion: a comparison of two models of synaptic vesicle dynamics. Biophys J 2007; 92:2271-80. [PMID: 17218458 PMCID: PMC1864819 DOI: 10.1529/biophysj.106.081794] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2006] [Accepted: 11/27/2006] [Indexed: 11/18/2022] Open
Abstract
Two models were recently proposed to enable us to understand the dynamics of synaptic vesicles in hippocampal neurons. In the caged diffusion model, the vesicles diffuse in small circular cages located randomly in the bouton, while in the stick-and-diffuse model the vesicles bind and release from a cellular cytomatrix. In this article, we obtain analytic expressions for the fluorescence correlation spectroscopy (FCS) autocorrelation function for the two models and test their predictions against our earlier FCS measurements of the vesicle dynamics. We find that the stick-and-diffuse model agrees much better with the experiment. We find also that, due to the slow dynamics of the vesicles, the finite experimental integration time has an important effect on the FCS autocorrelation function and demonstrate its effect for the different models. The two models of the dynamics are also relevant to other cellular environments where mobile species undergo slow diffusionlike motion in restricted spaces or bind and release from a stationary substrate.
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Affiliation(s)
- Chuck Yeung
- School of Science, Pennsylvania State University at Erie, The Behrend College, Erie, Pennsylvania, USA.
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46
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Abstract
FM dyes have been used to label and then monitor synaptic vesicles, secretory granules and other endocytic structures in a variety of preparations. Here, we describe the general procedure for using FM dyes to study endosomal trafficking in general, and synaptic vesicle recycling in particular. The dye, dissolved in normal saline solution, is added to a chamber containing the preparation to be labeled. Stimulation evokes exocytosis, and compensatory endocytosis that follows traps FM dye inside the retrieved vesicles. The extracellular dye is then washed from the chamber, and labeled endocytic structures are examined with a fluorescence microscope. Fluorescence intensity provides a direct measure of the labeled vesicle number, a good measure of the amount of exocytosis. If the preparation is stimulated again, without dye in the chamber, dimming of the preparation provides a measure of exocytosis of labeled vesicles. With a synaptic preparation on hand, this protocol requires 1 day.
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Affiliation(s)
- Michael A Gaffield
- Neuroscience Program, University of Colorado Medical School, Aurora, Colorado 80045, USA
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47
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Du W, Wang Y, Luo Q, Liu BF. Optical molecular imaging for systems biology: from molecule to organism. Anal Bioanal Chem 2006; 386:444-57. [PMID: 16850295 PMCID: PMC1592253 DOI: 10.1007/s00216-006-0541-z] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 05/01/2006] [Accepted: 05/09/2006] [Indexed: 11/25/2022]
Abstract
The development of highly efficient analytical methods capable of probing biological systems at system level is an important task that is required in order to meet the requirements of the emerging field of systems biology. Optical molecular imaging (OMI) is a very powerful tool for studying the temporal and spatial dynamics of specific biomolecules and their interactions in real time in vivo. In this article, recent advances in OMI are reviewed extensively, such as the development of molecular probes that make imaging brighter, more stable and more informative (e.g., FPs and semiconductor nanocrystals, also referred to as quantum dots), the development of imaging approaches that provide higher resolution and greater tissue penetration, and applications for measuring biological events from molecule to organism level, including gene expression, protein and subcellular compartment localization, protein activation and interaction, and low-mass molecule dynamics. These advances are of great significance in the field of biological science and could also be applied to disease diagnosis and pharmaceutical screening. Further developments in OMI for systems biology are also proposed.
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Affiliation(s)
- Wei Du
- The Key Laboratory of Biomedical Photonics of MOE—Hubei Bioinformatics & Molecular Imaging Key Laboratory, Department of Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074 People’s Republic of China
| | - Ying Wang
- The Key Laboratory of Biomedical Photonics of MOE—Hubei Bioinformatics & Molecular Imaging Key Laboratory, Department of Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074 People’s Republic of China
| | - Qingming Luo
- The Key Laboratory of Biomedical Photonics of MOE—Hubei Bioinformatics & Molecular Imaging Key Laboratory, Department of Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074 People’s Republic of China
| | - Bi-Feng Liu
- The Key Laboratory of Biomedical Photonics of MOE—Hubei Bioinformatics & Molecular Imaging Key Laboratory, Department of Systems Biology, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074 People’s Republic of China
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48
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Gaffield MA, Rizzoli SO, Betz WJ. Mobility of synaptic vesicles in different pools in resting and stimulated frog motor nerve terminals. Neuron 2006; 51:317-25. [PMID: 16880126 DOI: 10.1016/j.neuron.2006.06.031] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 05/30/2006] [Accepted: 06/26/2006] [Indexed: 11/27/2022]
Abstract
We used fluorescence recovery after photobleaching (FRAP) to measure the mobility of synaptic vesicles in frog motor nerve terminals. Vesicles belonging to the recycling pool or to the reserve pool were selectively labeled with FM1-43. In resting terminals, vesicles in the reserve pool were immobile, while vesicles in the recycling pool were mobile. Nerve stimulation increased the mobility of reserve pool vesicles. Treatment with latrunculin A, which destroyed actin filaments, had no significant effect on mobility, and reducing the temperature likewise had little effect, suggesting that recycling pool vesicles move by simple diffusion. Application of okadaic acid caused vesicle mobility in both pools to increase to the same level. We could model these and others' results quantitatively by taking into account the relative numbers of mobile and immobile vesicles in each pool, and vesicle packing density, which has a large effect on mobility.
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Affiliation(s)
- Michael A Gaffield
- Neuroscience Program, University of Colorado Medical School, Aurora, Colorado 80045, USA
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49
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Schweizer FE, Ryan TA. The synaptic vesicle: cycle of exocytosis and endocytosis. Curr Opin Neurobiol 2006; 16:298-304. [PMID: 16707259 DOI: 10.1016/j.conb.2006.05.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Accepted: 05/05/2006] [Indexed: 11/30/2022]
Abstract
Synaptic vesicles are clustered at the presynaptic terminal where they fuse and recycle in response to stimulation. Vesicles appear to be sorted into pools, but we do not yet understand how physiologically defined pools relate to morphological pools. The advent of dynamic imaging approaches has led to an appreciation of the regulation of vesicle mobility. Newly endocytosed vesicles are highly mobile but appear to become transiently trapped as they re-enter the recycling pool. Recent experiments indicate that endocytosis might have a constant rate, but limited capacity. How endocytosis is linked to exocytosis remains unclear, although calcium emerges as an important player.
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Affiliation(s)
- Felix E Schweizer
- Department of Neurobiology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Drive South, CHS 63-323, Los Angeles, CA 90095-1763, USA.
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50
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Kushmerick C, Renden R, von Gersdorff H. Physiological temperatures reduce the rate of vesicle pool depletion and short-term depression via an acceleration of vesicle recruitment. J Neurosci 2006; 26:1366-77. [PMID: 16452660 PMCID: PMC6675486 DOI: 10.1523/jneurosci.3889-05.2006] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The timing and strength of synaptic transmission is profoundly dependent on temperature. However, the temperature dependence of the multiple mechanisms that contribute to short-term synaptic plasticity is poorly understood. Here, we use voltage-clamp recordings to quantify the temperature dependence of exocytosis at the calyx of Held synapse. EPSC and miniature EPSC amplitudes were larger at physiological temperature, but quantal content during low-frequency (0.05 Hz) stimulation was constant after temperature jumps from 22-24 degrees C to 35-37 degrees C. The initial degree of EPSC depression during 100 Hz stimuli trains was unchanged with temperature, as were estimates of release probability and vesicle pool size. In contrast, physiological temperatures dramatically relieved depression measured after 40 stimuli at 100 Hz by increasing twofold the rate of recovery from depression. Presynaptic calyx recordings revealed that physiological temperature increased capacitance jumps resulting from 0.5 and 1 ms depolarizations by increasing Ca2+ influx. When Ca2+ entry was equalized at the two temperatures, exocytosis exhibited little temperature dependence for brief depolarizations. However, in response to longer depolarizations, raising temperature increased a slow phase of exocytosis, without affecting overall Ca2+ entry or the size of the readily releasable pool of vesicles. Higher temperatures also increased the rate of presynaptic Ca2+ current inactivation; nevertheless, the degree of steady-state EPSC depression was greatly reduced. Our results thus suggest that changes in steady-state EPSCs during stimulus trains at physiological temperature reflect larger quantal amplitudes and faster refilling of synaptic vesicle pools, leading to reduced short-term depression during prolonged high-frequency firing.
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