1
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Sharma B, Koren DT, Ghosh S. Nitric oxide modulates NMDA receptor through a negative feedback mechanism and regulates the dynamical behavior of neuronal postsynaptic components. Biophys Chem 2023; 303:107114. [PMID: 37832215 DOI: 10.1016/j.bpc.2023.107114] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 09/22/2023] [Accepted: 09/24/2023] [Indexed: 10/15/2023]
Abstract
Nitric oxide (NO) is known to be an important regulator of neurological processes in the central nervous system which acts directly on the presynaptic neuron and enhances the release of neurotransmitters like glutamate into the synaptic cleft. Calcium influx activates a cascade of biochemical reactions to influence the production of nitric oxide in the postsynaptic neuron. This has been modeled in the present work as a system of ordinary differential equations, to explore the dynamics of the interacting components and predict the dynamical behavior of the postsynaptic neuron. It has been hypothesized that nitric oxide modulates the NMDA receptor via a feedback mechanism and regulates the dynamic behavior of postsynaptic components. Results obtained by numerical analyses indicate that the biochemical system is stimulus-dependent and shows oscillations of calcium and other components within a limited range of concentration. Some of the parameters such as stimulus strength, extracellular calcium concentration, and rate of nitric oxide feedback are crucial for the dynamics of the components in the postsynaptic neuron.
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Affiliation(s)
- Bhanu Sharma
- Department of Biophysics, University of Delhi South Campus, New Delhi 110021, India
| | | | - Subhendu Ghosh
- Department of Biophysics, University of Delhi South Campus, New Delhi 110021, India.
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2
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Wang Y, Bergström J, Ingelsson M, Westermark GT. Studies on alpha-synuclein and islet amyloid polypeptide interaction. Front Mol Biosci 2023; 10:1080112. [PMID: 36793785 PMCID: PMC9922763 DOI: 10.3389/fmolb.2023.1080112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/16/2023] [Indexed: 01/31/2023] Open
Abstract
Introduction: Parkinson's disease and type 2 diabetes have both elements of local amyloid depositions in their pathogenesis. In Parkinson's disease, alpha-synuclein (aSyn) forms insoluble Lewy bodies and Lewy neurites in brain neurons, and in type 2 diabetes, islet amyloid polypeptide (IAPP) comprises the amyloid in the islets of Langerhans. In this study, we assessed the interaction between aSyn and IAPP in human pancreatic tissues, both ex vivo and in vitro. Material and Methods: The antibody-based detection techniques, proximity ligation assay (PLA), and immuno-TEM were used for co-localization studies. Bifluorescence complementation (BiFC) was used for interaction studies between IAPP and aSyn in HEK 293 cells. The Thioflavin T assay was used for studies of cross-seeding between IAPP and aSyn. ASyn was downregulated with siRNA, and insulin secretion was monitored using TIRF microscopy. Results: We demonstrate intracellular co-localization of aSyn with IAPP, while aSyn is absent in the extracellular amyloid deposits. ASyn reactivity is present in the secretory granules of β-cells and some α-cells in human islets. The BiFC-expression of aSyn/aSyn and IAPP/IAPP in HEK293 cells resulted in 29.3% and 19.7% fluorescent cells, respectively, while aSyn/IAPP co-expression resulted in ∼10% fluorescent cells. Preformed aSyn fibrils seeded IAPP fibril formation in vitro, but adding preformed IAPP seeds to aSyn did not change aSyn fibrillation. In addition, mixing monomeric aSyn with monomeric IAPP did not affect IAPP fibril formation. Finally, the knockdown of endogenous aSyn did not affect β cell function or viability, nor did overexpression of aSyn affect β cell viability. Discussion: Despite the proximity of aSyn and IAPP in β-cells and the detected capacity of preformed aSyn fibrils to seed IAPP in vitro, it is still an open question if an interaction between the two molecules is of pathogenic significance for type 2 diabetes.
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Affiliation(s)
- Ye Wang
- Departments of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Joakim Bergström
- Departments ofPublic Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | - Martin Ingelsson
- Departments ofPublic Health and Caring Sciences, Uppsala University, Uppsala, Sweden,Krembil Brain Institute, University Health Network, Toronto, ON, Canada,Department of Medicine and Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
| | - Gunilla T. Westermark
- Departments of Medical Cell Biology, Uppsala University, Uppsala, Sweden,*Correspondence: Gunilla T. Westermark,
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3
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Xue M, Cao Y, Shen C, Guo W. Computational Advances of Protein/Neurotransmitter-membrane Interactions Involved in Vesicle Fusion and Neurotransmitter Release. J Mol Biol 2023; 435:167818. [PMID: 36089056 DOI: 10.1016/j.jmb.2022.167818] [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: 05/31/2022] [Revised: 08/22/2022] [Accepted: 09/04/2022] [Indexed: 02/04/2023]
Abstract
Vesicle fusion is of crucial importance to neuronal communication at neuron terminals. The exquisite but complex fusion machinery for neurotransmitter release is tightly controlled and regulated by protein/neurotransmitter-membrane interactions. Computational 'microscopies', in particular molecular dynamics simulations and related techniques, have provided notable insight into the physiological process over the past decades, and have made enormous contributions to fields such as neurology, pharmacology and pathophysiology. Here we review the computational advances of protein/neurotransmitter-membrane interactions related to presynaptic vesicle-membrane fusion and neurotransmitter release, and outline the in silico challenges ahead for understanding this important physiological process.
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Affiliation(s)
- Minmin Xue
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Yuwei Cao
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, China
| | - Chun Shen
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
| | - Wanlin Guo
- Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Education, State Key Laboratory of Mechanics and Control of Mechanical Structures, and Institute for Frontier Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China; State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, China.
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4
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Cappelletti P, Filareti M, Masuelli L, Bei R, Hassanzadeh K, Corbo M, Feligioni M. Syntaxin-1a and SNAP-25 expression level is increased in the blood samples of ischemic stroke patients. Sci Rep 2022; 12:14483. [PMID: 36008522 PMCID: PMC9411545 DOI: 10.1038/s41598-022-18719-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 08/18/2022] [Indexed: 11/09/2022] Open
Abstract
The interest for the discovery of blood biomarkers for several neurological disorders, including Ischemic Stroke (IS), is growing and their identification in blood samples would be revolutionary allowing a fast and better pathology prediction or outcome and to collect information on patient recovery. The increased permeability of the blood-brain barrier, following a brain infarct, allows the detection of brain proteins in the blood flow. In this work, we analyzed the expression levels of two synaptic proteins Syntaxin (STX)-1a and Synaptosomal Associated Protein, 25 kDa (SNAP-25), in Peripheral Blood Mononuclear Cell (PBMC), serum and in Neuronal Derived Extracellular vesicles (NDEs) of IS patients, age and sex matched healthy control (HC) and younger HC (Y-HC). Interestingly, we identified STX-1a protein in the cytoplasm of PBMC and both STX-1a and SNAP-25 expression levels were significantly augmented in all IS patient's blood fractions compared to control subjects. In addition, STX-1a blood levels correlated with the IS clinical scales National Institutes of Health Stroke Scale (NIH-SS) and the modified Barthel Index (BI). These results prompted us to speculate that STX-1a and SNAP-25 hematic fluctuations depict the brain damage after an ischemic attack and that their hematic detection could represent a novel and accessible IS biomarkers.
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Affiliation(s)
- Pamela Cappelletti
- Department of Neuro-Rehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
| | - Melania Filareti
- Department of Neuro-Rehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
| | - Laura Masuelli
- Department of Experimental Medicine, University of Rome "Sapienza", Rome, Italy
| | - Roberto Bei
- Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - Kambiz Hassanzadeh
- European Brain Research Institute (EBRI) Rita Levi Montalcini Foundation, Viale Regina Elena 295, 00161, Rome, Italy.,Fondazione Pisana per la Scienza (FPS), Pisa, Italy
| | - Massimo Corbo
- Department of Neuro-Rehabilitation Sciences, Casa Cura Policlinico, Milan, Italy
| | - Marco Feligioni
- Department of Neuro-Rehabilitation Sciences, Casa Cura Policlinico, Milan, Italy. .,European Brain Research Institute (EBRI) Rita Levi Montalcini Foundation, Viale Regina Elena 295, 00161, Rome, Italy.
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5
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Han Y, Cao R, Qin L, Chen LY, Tang AH, Südhof TC, Zhang B. Neuroligin-3 confines AMPA receptors into nanoclusters, thereby controlling synaptic strength at the calyx of Held synapses. SCIENCE ADVANCES 2022; 8:eabo4173. [PMID: 35704570 PMCID: PMC9200272 DOI: 10.1126/sciadv.abo4173] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/02/2022] [Indexed: 05/30/2023]
Abstract
The subsynaptic organization of postsynaptic neurotransmitter receptors into nanoclusters that are aligned with presynaptic release sites is essential for the high fidelity of synaptic transmission. However, the mechanisms controlling the nanoscale organization of neurotransmitter receptors in vivo remain incompletely understood. Here, we deconstructed the role of neuroligin-3 (Nlgn3), a postsynaptic adhesion molecule linked to autism, in organizing AMPA-type glutamate receptors in the calyx of Held synapse. Deletion of Nlgn3 lowered the amplitude and slowed the kinetics of AMPA receptor-mediated synaptic responses. Super-resolution microscopy revealed that, unexpectedly, these impairments in synaptic transmission were associated with an increase in the size of postsynaptic PSD-95 and AMPA receptor nanoclusters but a decrease of the densities in these clusters. Modeling showed that a dilution of AMPA receptors into larger nanocluster volumes decreases synaptic strength. Nlgn3, likely by binding to presynaptic neurexins, thus is a key organizer of AMPA receptor nanoclusters that likely acts via PSD-95 adaptors to optimize the fidelity of synaptic transmission.
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Affiliation(s)
- Ying Han
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Ran Cao
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei 230026, China
- CAS Key Laboratory of Brain Function and Disease, Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics and Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Liming Qin
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen 518132, China
| | - Lulu Y. Chen
- Department of Anatomy and Neurobiology, University of California, Irvine, Irvine, CA 92697, USA
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94043, USA
| | - Ai-Hui Tang
- Institute of Artificial Intelligence, Hefei Comprehensive National Science Center, Hefei 230026, China
- CAS Key Laboratory of Brain Function and Disease, Ministry of Education Key Laboratory for Membrane-less Organelles & Cellular Dynamics and Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Thomas C. Südhof
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94043, USA
| | - Bo Zhang
- School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen 518132, China
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6
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Abstract
Major recent advances and previous data have led to a plausible model of how key proteins mediate neurotransmitter release. In this model, the soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (SNAP) receptor (SNARE) proteins syntaxin-1, SNAP-25, and synaptobrevin form tight complexes that bring the membranes together and are crucial for membrane fusion. NSF and SNAPs disassemble SNARE complexes and ensure that fusion occurs through an exquisitely regulated pathway that starts with Munc18-1 bound to a closed conformation of syntaxin-1. Munc18-1 also binds to synaptobrevin, forming a template to assemble the SNARE complex when Munc13-1 opens syntaxin-1 while bridging the vesicle and plasma membranes. Synaptotagmin-1 and complexin bind to partially assembled SNARE complexes, likely stabilizing them and preventing fusion until Ca2+ binding to synaptotagmin-1 causes dissociation from the SNARE complex and induces interactions with phospholipids that help trigger release. Although fundamental questions remain about the mechanism of membrane fusion, these advances provide a framework to investigate the mechanisms underlying presynaptic plasticity.
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Affiliation(s)
- Josep Rizo
- Departments of Biophysics, Biochemistry, and Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA;
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7
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Abstract
Rapid and precise neuronal communication is enabled through a highly synchronous release of signaling molecules neurotransmitters within just milliseconds of the action potential. Yet neurotransmitter release lacks a theoretical framework that is both phenomenologically accurate and mechanistically realistic. Here, we present an analytic theory of the action-potential-triggered neurotransmitter release at the chemical synapse. The theory is demonstrated to be in detailed quantitative agreement with existing data on a wide variety of synapses from electrophysiological recordings in vivo and fluorescence experiments in vitro. Despite up to ten orders of magnitude of variation in the release rates among the synapses, the theory reveals that synaptic transmission obeys a simple, universal scaling law, which we confirm through a collapse of the data from strikingly diverse synapses onto a single master curve. This universality is complemented by the capacity of the theory to readily extract, through a fit to the data, the kinetic and energetic parameters that uniquely identify each synapse. The theory provides a means to detect cooperativity among the SNARE complexes that mediate vesicle fusion and reveals such cooperativity in several existing data sets. The theory is further applied to establish connections between molecular constituents of synapses and synaptic function. The theory allows competing hypotheses of short-term plasticity to be tested and identifies the regimes where particular mechanisms of synaptic facilitation dominate or, conversely, fail to account for the existing data for the paired-pulse ratio. The derived trade-off relation between the transmission rate and fidelity shows how transmission failure can be controlled by changing the microscopic properties of the vesicle pool and SNARE complexes. The established condition for the maximal synaptic efficacy reveals that no fine tuning is needed for certain synapses to maintain near-optimal transmission. We discuss the limitations of the theory and propose possible routes to extend it. These results provide a quantitative basis for the notion that the molecular-level properties of synapses are crucial determinants of the computational and information-processing functions in synaptic transmission.
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Affiliation(s)
- Bin Wang
- Department of Physics, University of California, San DiegoLa JollaUnited States
| | - Olga K Dudko
- Department of Physics, University of California, San DiegoLa JollaUnited States
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8
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Nikolaus J, Hancock K, Tsemperouli M, Baddeley D, Karatekin E. Optimal Detection of Fusion Pore Dynamics Using Polarized Total Internal Reflection Fluorescence Microscopy. Front Mol Biosci 2021; 8:740408. [PMID: 34859048 PMCID: PMC8631473 DOI: 10.3389/fmolb.2021.740408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 10/06/2021] [Indexed: 11/13/2022] Open
Abstract
The fusion pore is the initial narrow connection that forms between fusing membranes. During vesicular release of hormones or neurotransmitters, the nanometer-sized fusion pore may open-close repeatedly (flicker) before resealing or dilating irreversibly, leading to kiss-and-run or full-fusion events, respectively. Pore dynamics govern vesicle cargo release and the mode of vesicle recycling, but the mechanisms are poorly understood. This is partly due to a lack of reconstituted assays that combine single-pore sensitivity and high time resolution. Total internal reflection fluorescence (TIRF) microscopy offers unique advantages for characterizing single membrane fusion events, but signals depend on effects that are difficult to disentangle, including the polarization of the excitation electric field, vesicle size, photobleaching, orientation of the excitation dipoles of the fluorophores with respect to the membrane, and the evanescent field depth. Commercial TIRF microscopes do not allow control of excitation polarization, further complicating analysis. To overcome these challenges, we built a polarization-controlled total internal reflection fluorescence (pTIRF) microscope and monitored fusion of proteoliposomes with planar lipid bilayers with single molecule sensitivity and ∼15 ms temporal resolution. Using pTIRF microscopy, we detected docking and fusion of fluorescently labeled small unilamellar vesicles, reconstituted with exocytotic/neuronal v-SNARE proteins (vSUVs), with a supported bilayer containing the cognate t-SNAREs (tSBL). By varying the excitation polarization angle, we were able to identify a dye-dependent optimal polarization at which the fluorescence increase upon fusion was maximal, facilitating event detection and analysis of lipid transfer kinetics. An improved algorithm allowed us to estimate the size of the fusing vSUV and the fusion pore openness (the fraction of time the pore is open) for every event. For most events, lipid transfer was much slower than expected for diffusion through an open pore, suggesting that fusion pore flickering limits lipid release. We find a weak correlation between fusion pore openness and vesicle area. The approach can be used to study mechanisms governing fusion pore dynamics in a wide range of membrane fusion processes.
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Affiliation(s)
- Joerg Nikolaus
- Cellular and Molecular Physiology, Yale University, New Haven, CT, United States
- Nanobiology Institute, Yale University, West Haven, CT, United States
| | - Kasey Hancock
- Cellular and Molecular Physiology, Yale University, New Haven, CT, United States
- Nanobiology Institute, Yale University, West Haven, CT, United States
- Integrated Physical and Engineering Biology Program, Yale University, New Haven, CT, United States
| | - Maria Tsemperouli
- Cellular and Molecular Physiology, Yale University, New Haven, CT, United States
- Nanobiology Institute, Yale University, West Haven, CT, United States
| | - David Baddeley
- Nanobiology Institute, Yale University, West Haven, CT, United States
- Cell Biology, Yale University, New Haven, CT, United States
| | - Erdem Karatekin
- Cellular and Molecular Physiology, Yale University, New Haven, CT, United States
- Nanobiology Institute, Yale University, West Haven, CT, United States
- Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, United States
- Saints-Pères Paris Institute for the Neurosciences (SPPIN), Université de Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France
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9
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Vardar G, Salazar-Lázaro A, Brockmann M, Weber-Boyvat M, Zobel S, Kumbol VWA, Trimbuch T, Rosenmund C. Reexamination of N-terminal domains of syntaxin-1 in vesicle fusion from central murine synapses. eLife 2021; 10:69498. [PMID: 34427183 PMCID: PMC8416022 DOI: 10.7554/elife.69498] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 08/23/2021] [Indexed: 01/11/2023] Open
Abstract
Syntaxin-1 (STX1) and Munc18-1 are two requisite components of synaptic vesicular release machinery, so much so synaptic transmission cannot proceed in their absence. They form a tight complex through two major binding modes: through STX1’s N-peptide and through STX1’s closed conformation driven by its Habc- domain. However, physiological roles of these two reportedly different binding modes in synapses are still controversial. Here we characterized the roles of STX1’s N-peptide, Habc-domain, and open conformation with and without N-peptide deletion using our STX1-null mouse model system and exogenous reintroduction of STX1A mutants. We show, on the contrary to the general view, that the Habc-domain is absolutely required and N-peptide is dispensable for synaptic transmission. However, STX1A’s N-peptide plays a regulatory role, particularly in the Ca2+-sensitivity and the short-term plasticity of vesicular release, whereas STX1’s open conformation governs the vesicle fusogenicity. Strikingly, we also show neurotransmitter release still proceeds when the two interaction modes between STX1A and Munc18-1 are presumably intervened, necessitating a refinement of the conceptualization of STX1A–Munc18-1 interaction.
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Affiliation(s)
- Gülçin Vardar
- Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Andrea Salazar-Lázaro
- Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Marisa Brockmann
- Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Marion Weber-Boyvat
- Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Sina Zobel
- Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | | | - Thorsten Trimbuch
- Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
| | - Christian Rosenmund
- Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Berlin Institute of Health, Berlin, Germany
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10
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Delgado JY. Lack of support for surface diffusion of postsynaptic AMPARs in tuning synaptic transmission. Biophys J 2021; 120:3409-3417. [PMID: 34214532 DOI: 10.1016/j.bpj.2021.06.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/19/2021] [Accepted: 06/17/2021] [Indexed: 10/21/2022] Open
Abstract
Repetitive stimulation of excitatory synapses triggers molecular events required for signal transfer across neuronal synapses. It has been hypothesized that one of these molecular events, the diffusion of extrasynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPARs) (i.e., the diffusion hypothesis), is necessary to help synapses recover from paired-pulse depression. To examine this presumed role of AMPAR diffusion during repetitive presynaptic stimulation, a biophysical model based on published physiological results was developed to track the localization and gating of each AMPAR. The model demonstrates that AMPAR gating in short intervals of fewer than 100 ms is controlled by their position in relation to the glutamate release site and by their recovery from desensitization, but it is negligibly influenced by their diffusion. Therefore, these simulations failed to demonstrate a role for AMPAR diffusion in helping synapses recover from paired-pulse depression.
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Affiliation(s)
- Jary Y Delgado
- Department of Biology, University of Chicago, Chicago, Illinois.
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11
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Wu Z, Dharan N, McDargh ZA, Thiyagarajan S, O'Shaughnessy B, Karatekin E. The neuronal calcium sensor Synaptotagmin-1 and SNARE proteins cooperate to dilate fusion pores. eLife 2021; 10:68215. [PMID: 34190041 PMCID: PMC8294851 DOI: 10.7554/elife.68215] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/29/2021] [Indexed: 02/07/2023] Open
Abstract
All membrane fusion reactions proceed through an initial fusion pore, including calcium-triggered release of neurotransmitters and hormones. Expansion of this small pore to release cargo is energetically costly and regulated by cells, but the mechanisms are poorly understood. Here, we show that the neuronal/exocytic calcium sensor Synaptotagmin-1 (Syt1) promotes expansion of fusion pores induced by SNARE proteins. Pore dilation relied on calcium-induced insertion of the tandem C2 domain hydrophobic loops of Syt1 into the membrane, previously shown to reorient the C2 domain. Mathematical modelling suggests that C2B reorientation rotates a bound SNARE complex so that it exerts force on the membranes in a mechanical lever action that increases the height of the fusion pore, provoking pore dilation to offset the bending energy penalty. We conclude that Syt1 exerts novel non-local calcium-dependent mechanical forces on fusion pores that dilate pores and assist neurotransmitter and hormone release.
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Affiliation(s)
- Zhenyong Wu
- Department of Cellular and Molecular Physiology, Yale University, New Haven, United States.,Nanobiology Institute, Yale University, West Haven, United States
| | - Nadiv Dharan
- Department of Chemical Engineering, Columbia University, New York, United States
| | - Zachary A McDargh
- Department of Chemical Engineering, Columbia University, New York, United States
| | - Sathish Thiyagarajan
- Department of Chemical Engineering, Columbia University, New York, United States
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, United States
| | - Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University, New Haven, United States.,Nanobiology Institute, Yale University, West Haven, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.,Saints-Pères Paris Institute for the Neurosciences (SPPIN), Université de Paris, Centre National de la Recherche Scientifique (CNRS) UMR 8003, Paris, France
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12
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Vilcaes AA, Chanaday NL, Kavalali ET. Interneuronal exchange and functional integration of synaptobrevin via extracellular vesicles. Neuron 2021; 109:971-983.e5. [PMID: 33513363 PMCID: PMC7979516 DOI: 10.1016/j.neuron.2021.01.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 12/06/2020] [Accepted: 01/07/2021] [Indexed: 12/25/2022]
Abstract
Recent studies have investigated the composition and functional effects of extracellular vesicles (EVs) secreted by a variety of cell types. However, the mechanisms underlying the impact of these vesicles on neurotransmission remain unclear. Here, we isolated EVs secreted by rat and mouse hippocampal neurons and found that they contain synaptic-vesicle-associated proteins, in particular the vesicular SNARE (soluble N-ethylmaleimide-sensitive factor [NSF]-attachment protein receptor) synaptobrevin (also called VAMP). Using a combination of electrophysiology and live-fluorescence imaging, we demonstrate that this extracellular pool of synaptobrevins can rapidly integrate into the synaptic vesicle cycle of host neurons via a CD81-dependent process and selectively augment inhibitory neurotransmission as well as specifically rescue neurotransmission in synapses deficient in synaptobrevin. These findings uncover a novel means of interneuronal communication and functional coupling via exchange of vesicular SNAREs.
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Affiliation(s)
- A Alejandro Vilcaes
- CONICET, Universidad Nacional de Córdoba, Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Córdoba X5000HUA, Argentina; Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Córdoba X5000HUA, Argentina; Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA
| | - Natali L Chanaday
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA.
| | - Ege T Kavalali
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240-7933, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232-2050, USA.
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13
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Function of Drosophila Synaptotagmins in membrane trafficking at synapses. Cell Mol Life Sci 2021; 78:4335-4364. [PMID: 33619613 PMCID: PMC8164606 DOI: 10.1007/s00018-021-03788-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 12/13/2022]
Abstract
The Synaptotagmin (SYT) family of proteins play key roles in regulating membrane trafficking at neuronal synapses. Using both Ca2+-dependent and Ca2+-independent interactions, several SYT isoforms participate in synchronous and asynchronous fusion of synaptic vesicles (SVs) while preventing spontaneous release that occurs in the absence of stimulation. Changes in the function or abundance of the SYT1 and SYT7 isoforms alter the number and route by which SVs fuse at nerve terminals. Several SYT family members also regulate trafficking of other subcellular organelles at synapses, including dense core vesicles (DCV), exosomes, and postsynaptic vesicles. Although SYTs are linked to trafficking of multiple classes of synaptic membrane compartments, how and when they interact with lipids, the SNARE machinery and other release effectors are still being elucidated. Given mutations in the SYT family cause disorders in both the central and peripheral nervous system in humans, ongoing efforts are defining how these proteins regulate vesicle trafficking within distinct neuronal compartments. Here, we review the Drosophila SYT family and examine their role in synaptic communication. Studies in this invertebrate model have revealed key similarities and several differences with the predicted activity of their mammalian counterparts. In addition, we highlight the remaining areas of uncertainty in the field and describe outstanding questions on how the SYT family regulates membrane trafficking at nerve terminals.
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14
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Fionda L, Turon‐Sans J, Fuentes Prior P, Bernal Noguera S, Cortés‐Vicente E, López‐Pérez MA, Gallardo E, Rojas‐García R. A new
de novo SYT2
mutation presenting as distal weakness. Neuropathy or neuromuscular junction dysfunction? J Peripher Nerv Syst 2020; 26:113-117. [DOI: 10.1111/jns.12425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/08/2020] [Accepted: 12/08/2020] [Indexed: 01/10/2023]
Affiliation(s)
- Laura Fionda
- Neuromuscular and Rare Disease Center, Department of Neuroscience Mental Health and Sensory Organs (NESMOS), Sant'Andrea Hospital, Sapienza University of Rome Rome Italy
| | - Janina Turon‐Sans
- Neuromuscular Diseases Unit, Department of Neurology Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER IICS‐Madrid Spain
| | - Pablo Fuentes Prior
- Biomedical Research Institute (IIB) Molecular Bases of Disease Hospital de la Santa Creu i Sant Pau Barcelona Spain
| | - Sara Bernal Noguera
- Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER IICS‐Madrid Spain
- Biomedical Research Institute (IIB) Molecular Bases of Disease Hospital de la Santa Creu i Sant Pau Barcelona Spain
| | - Elena Cortés‐Vicente
- Neuromuscular Diseases Unit, Department of Neurology Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER IICS‐Madrid Spain
| | | | - Eduard Gallardo
- Neuromuscular Diseases Unit, Department of Neurology Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER IICS‐Madrid Spain
| | - Ricard Rojas‐García
- Neuromuscular Diseases Unit, Department of Neurology Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras CIBERER IICS‐Madrid Spain
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15
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Tien CW, Yu B, Huang M, Stepien KP, Sugita K, Xie X, Han L, Monnier PP, Zhen M, Rizo J, Gao S, Sugita S. Open syntaxin overcomes exocytosis defects of diverse mutants in C. elegans. Nat Commun 2020; 11:5516. [PMID: 33139696 PMCID: PMC7606450 DOI: 10.1038/s41467-020-19178-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 10/01/2020] [Indexed: 11/09/2022] Open
Abstract
Assembly of SNARE complexes that mediate neurotransmitter release requires opening of a ‘closed’ conformation of UNC-64/syntaxin. Rescue of unc-13/Munc13 mutant phenotypes by overexpressed open UNC-64/syntaxin suggested a specific function of UNC-13/Munc13 in opening UNC-64/ syntaxin. Here, we revisit the effects of open unc-64/syntaxin by generating knockin (KI) worms. The KI animals exhibit enhanced spontaneous and evoked exocytosis compared to WT animals. Unexpectedly, the open syntaxin KI partially suppresses exocytosis defects of various mutants, including snt-1/synaptotagmin, unc-2/P/Q/N-type Ca2+ channel alpha-subunit and unc-31/CAPS, in addition to unc-13/Munc13 and unc-10/RIM, and enhanced exocytosis in tom-1/Tomosyn mutants. However, open syntaxin aggravates the defects of unc-18/Munc18 mutants. Correspondingly, open syntaxin partially bypasses the requirement of Munc13 but not Munc18 for liposome fusion. Our results show that facilitating opening of syntaxin enhances exocytosis in a wide range of genetic backgrounds, and may provide a general means to enhance synaptic transmission in normal and disease states. Opening of the UNC-64/syntaxin closed conformation by UNC-13/Munc13 to form the neuronal SNARE complex is critical for neurotransmitter release. Here the authors show that facilitating the opening of syntaxin enhances exocytosis not only in unc-13 nulls as well as in diverse C. elegans mutants.
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Affiliation(s)
- Chi-Wei Tien
- Division of Fundamental Neurobiology, Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada, M5T 2S8.,Faculty of Medicine, Department of Physiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Bin Yu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Mengjia Huang
- Division of Fundamental Neurobiology, Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada, M5T 2S8.,Faculty of Medicine, Department of Physiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Karolina P Stepien
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kyoko Sugita
- Division of Genetics and Development, Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada, M5T 2S8
| | - Xiaoyu Xie
- Division of Fundamental Neurobiology, Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada, M5T 2S8.,Department of Anesthesiology, Dalian Medical University, Dalian, Liaoning, China
| | - Liping Han
- Department of Anesthesiology, Dalian Medical University, Dalian, Liaoning, China.,Department of Anesthesiology, Dalian Municipal Friendship Hospital, Dalian Medical University, Dalian, Liaoning, China
| | - Philippe P Monnier
- Faculty of Medicine, Department of Physiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.,Division of Genetics and Development, Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada, M5T 2S8.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Mei Zhen
- Faculty of Medicine, Department of Physiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.,Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada, M5G 1X5.,Faculty of Medicine, Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA. .,Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA. .,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
| | - Shangbang Gao
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Shuzo Sugita
- Division of Fundamental Neurobiology, Krembil Brain Institute, University Health Network, Toronto, Ontario, Canada, M5T 2S8. .,Faculty of Medicine, Department of Physiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.
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16
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Chung YS, Choo BKM, Ahmed PK, Othman I, Shaikh MF. Orthosiphon stamineus Proteins Alleviate Pentylenetetrazol-Induced Seizures in Zebrafish. Biomedicines 2020; 8:biomedicines8070191. [PMID: 32630817 PMCID: PMC7400404 DOI: 10.3390/biomedicines8070191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 02/08/2023] Open
Abstract
The anticonvulsive potential of proteins extracted from Orthosiphon stamineus leaves (OSLP) has never been elucidated in zebrafish (Danio rerio). This study thus aims to elucidate the anticonvulsive potential of OSLP in pentylenetetrazol (PTZ)-induced seizure model. Physical changes (seizure score and seizure onset time, behavior, locomotor) and neurotransmitter analysis were elucidated to assess the pharmacological activity. The protective mechanism of OSLP on brain was also studied using mass spectrometry-based label-free proteomic quantification (LFQ) and bioinformatics. OSLP was found to be safe up to 800 µg/kg and pre-treatment with OSLP (800 µg/kg, i.p., 30 min) decreased the frequency of convulsive activities (lower seizure score and prolonged seizure onset time), improved locomotor behaviors (reduced erratic swimming movements and bottom-dwelling habit), and lowered the excitatory neurotransmitter (glutamate). Pre-treatment with OSLP increased protein Complexin 2 (Cplx 2) expression in the zebrafish brain. Cplx2 is an important regulator in the trans-SNARE complex which is required during the vesicle priming phase in the calcium-dependent synaptic vesicle exocytosis. Findings in this study collectively suggests that OSLP could be regulating the release of neurotransmitters via calcium-dependent synaptic vesicle exocytosis mediated by the "Synaptic Vesicle Cycle" pathway. OSLP's anticonvulsive actions could be acting differently from diazepam (DZP) and with that, it might not produce the similar cognitive insults such as DZP.
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Affiliation(s)
- Yin-Sir Chung
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Malaysia; (Y.-S.C.); (B.K.M.C.); (I.O.)
- Liquid Chromatography-Mass Spectrometry (LCMS) Platform, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Malaysia
| | - Brandon Kar Meng Choo
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Malaysia; (Y.-S.C.); (B.K.M.C.); (I.O.)
| | - Pervaiz Khalid Ahmed
- School of Business, Monash University Malaysia, Bandar Sunway 47500, Malaysia;
- Global Asia in the 21st Century (GA21), Monash University Malaysia, Bandar Sunway 47500, Malaysia
| | - Iekhsan Othman
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Malaysia; (Y.-S.C.); (B.K.M.C.); (I.O.)
- Liquid Chromatography-Mass Spectrometry (LCMS) Platform, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Malaysia
| | - Mohd. Farooq Shaikh
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Malaysia; (Y.-S.C.); (B.K.M.C.); (I.O.)
- Correspondence:
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17
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Disney AA, Higley MJ. Diverse Spatiotemporal Scales of Cholinergic Signaling in the Neocortex. J Neurosci 2020; 40:720-725. [PMID: 31969490 PMCID: PMC6975298 DOI: 10.1523/jneurosci.1306-19.2019] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/16/2019] [Accepted: 10/21/2019] [Indexed: 12/18/2022] Open
Abstract
ACh is a signaling molecule in the mammalian CNS, with well-documented influence over cognition and behavior. However, the nature of cholinergic signaling in the brain remains controversial, with ongoing debates focused on the spatial and temporal resolution of ACh activity. Generally, opposing views have embraced a dichotomy between transmission as slow and volume-mediated versus fast and synaptic. Here, we provide the perspective that ACh, like most other neurotransmitters, exhibits both fast and slow modes that are strongly determined by the anatomy of cholinergic fibers, the distribution and the signaling mechanisms of receptor subtypes, and the dynamics of ACh hydrolysis. Current methodological approaches remain limited in their ability to provide detailed analyses of these underlying factors. However, we believe that the continued development of novel technologies in combination with a more nuanced view of cholinergic activity will open critical new avenues to a better understanding of ACh in the brain.Dual Perspectives Companion Paper: Forebrain Cholinergic Signaling: Wired and Phasic, Not Tonic, and Causing Behavior, by Martin Sarter and Cindy Lustig.
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Affiliation(s)
- Anita A Disney
- Department of Neurobiology, Duke University, Durham, North Carolina 27710, and
| | - Michael J Higley
- Department of Neuroscience, Kavli Institute for Neuroscience, Yale University, New Haven, Connecticut 06520
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18
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SNAP-25 Puts SNAREs at Center Stage in Metabolic Disease. Neuroscience 2019; 420:86-96. [DOI: 10.1016/j.neuroscience.2018.07.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/12/2018] [Accepted: 07/19/2018] [Indexed: 12/20/2022]
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19
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Brockmann MM, Maglione M, Willmes CG, Stumpf A, Bouazza BA, Velasquez LM, Grauel MK, Beed P, Lehmann M, Gimber N, Schmoranzer J, Sigrist SJ, Rosenmund C, Schmitz D. RIM-BP2 primes synaptic vesicles via recruitment of Munc13-1 at hippocampal mossy fiber synapses. eLife 2019; 8:43243. [PMID: 31535974 PMCID: PMC6752948 DOI: 10.7554/elife.43243] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 08/12/2019] [Indexed: 12/29/2022] Open
Abstract
All synapses require fusion-competent vesicles and coordinated Ca2+-secretion coupling for neurotransmission, yet functional and anatomical properties are diverse across different synapse types. We show that the presynaptic protein RIM-BP2 has diversified functions in neurotransmitter release at different central murine synapses and thus contributes to synaptic diversity. At hippocampal pyramidal CA3-CA1 synapses, RIM-BP2 loss has a mild effect on neurotransmitter release, by only regulating Ca2+-secretion coupling. However, at hippocampal mossy fiber synapses, RIM-BP2 has a substantial impact on neurotransmitter release by promoting vesicle docking/priming and vesicular release probability via stabilization of Munc13-1 at the active zone. We suggest that differences in the active zone organization may dictate the role a protein plays in synaptic transmission and that differences in active zone architecture is a major determinant factor in the functional diversity of synapses.
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Affiliation(s)
- Marisa M Brockmann
- Institut für Neurophysiologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Marta Maglione
- Freie Universität Berlin, Institut für Biologie, Berlin, Germany.,Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,NeuroCure Cluster of Excellence, Berlin, Germany
| | | | - Alexander Stumpf
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Boris A Bouazza
- Institut für Neurophysiologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Laura M Velasquez
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - M Katharina Grauel
- Institut für Neurophysiologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Prateep Beed
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Niclas Gimber
- Neuroscience Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | | | - Stephan J Sigrist
- Freie Universität Berlin, Institut für Biologie, Berlin, Germany.,NeuroCure Cluster of Excellence, Berlin, Germany.,DZNE, German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Christian Rosenmund
- Institut für Neurophysiologie, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,NeuroCure Cluster of Excellence, Berlin, Germany
| | - Dietmar Schmitz
- NeuroCure Cluster of Excellence, Berlin, Germany.,DZNE, German Center for Neurodegenerative Diseases, Berlin, Germany.,Neuroscience Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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20
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The effects of proteasome on baseline and methamphetamine-dependent dopamine transmission. Neurosci Biobehav Rev 2019; 102:308-317. [DOI: 10.1016/j.neubiorev.2019.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 04/29/2019] [Accepted: 05/09/2019] [Indexed: 12/16/2022]
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21
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The selective disruption of presynaptic JNK2/STX1a interaction reduces NMDA receptor-dependent glutamate release. Sci Rep 2019; 9:7146. [PMID: 31073146 PMCID: PMC6509125 DOI: 10.1038/s41598-019-43709-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 04/22/2019] [Indexed: 11/09/2022] Open
Abstract
The neuronal loss caused by excessive glutamate release, or ‘excitotoxicity’, leads to several pathological conditions, including cerebral ischemia, epilepsy, and neurodegenerative diseases. Over-stimulation of presynaptic N-methyl-D-aspartate (NMDA) receptors is known to trigger and support glutamate spillover, while postsynaptic NMDA receptors are responsible for the subsequent apoptotic cascade. Almost all molecules developed so far are unable to selectively block presynaptic or postsynaptic NMDA receptors, therefore a deeper knowledge about intracellular NMDA pathways is required to design more specific inhibitors. Our previous work showed that presynaptic c-Jun N-terminal kinase 2 (JNK2) specifically regulates NMDA-evoked glutamate release and here we demonstrate that an interaction between Syntaxin-1a and JNK2 is fundamental to this mechanism. Based on this evidence, a new cell permeable peptide (CPP), “JGRi1”, has been developed to disrupt the JNK2/STX1a interaction to indirectly, but specifically, inhibit presynaptic NMDA receptor signaling. JGRi1 reduces the NMDA-evoked release of glutamate both in in-vitro and ex-vivo experiments while also being able to widely diffuse throughout brain tissue via intraperitoneal administration. In conclusion, the JNK2/STX1 interaction is involved in presynaptic NMDA-evoked glutamate release and the novel CPP, JGRi1, acts as a pharmacological tool that promotes neuroprotection.
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22
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Shaaban A, Dhara M, Frisch W, Harb A, Shaib AH, Becherer U, Bruns D, Mohrmann R. The SNAP-25 linker supports fusion intermediates by local lipid interactions. eLife 2019; 8:41720. [PMID: 30883328 PMCID: PMC6422494 DOI: 10.7554/elife.41720] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 03/05/2019] [Indexed: 12/22/2022] Open
Abstract
SNAP-25 is an essential component of SNARE complexes driving fast Ca2+-dependent exocytosis. Yet, the functional implications of the tandem-like structure of SNAP-25 are unclear. Here, we have investigated the mechanistic role of the acylated “linker” domain that concatenates the two SNARE motifs within SNAP-25. Refuting older concepts of an inert connector, our detailed structure-function analysis in murine chromaffin cells demonstrates that linker motifs play a crucial role in vesicle priming, triggering, and fusion pore expansion. Mechanistically, we identify two synergistic functions of the SNAP-25 linker: First, linker motifs support t-SNARE interactions and accelerate ternary complex assembly. Second, the acylated N-terminal linker segment engages in local lipid interactions that facilitate fusion triggering and pore evolution, putatively establishing a favorable membrane configuration by shielding phospholipid headgroups and affecting curvature. Hence, the linker is a functional part of the fusion complex that promotes secretion by SNARE interactions as well as concerted lipid interplay.
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Affiliation(s)
- Ahmed Shaaban
- ZHMB, Saarland University, Homburg, Germany.,Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Madhurima Dhara
- Institute for Physiology, Center of Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Walentina Frisch
- Institute for Physiology, Center of Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Ali Harb
- ZHMB, Saarland University, Homburg, Germany
| | - Ali H Shaib
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Ute Becherer
- Institute for Physiology, Center of Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Dieter Bruns
- Institute for Physiology, Center of Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Ralf Mohrmann
- ZHMB, Saarland University, Homburg, Germany.,Institute for Physiology, Otto-von-Guericke University, Magdeburg, Germany.,Center for Behavioral Brain Science, Otto-von-Guericke University, Magdeburg, Germany
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23
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Manca F, Pincet F, Truskinovsky L, Rothman JE, Foret L, Caruel M. SNARE machinery is optimized for ultrafast fusion. Proc Natl Acad Sci U S A 2019; 116:2435-2442. [PMID: 30700546 PMCID: PMC6377469 DOI: 10.1073/pnas.1820394116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
SNARE proteins zipper to form complexes (SNAREpins) that power vesicle fusion with target membranes in a variety of biological processes. A single SNAREpin takes about 1 s to fuse two bilayers, yet a handful can ensure release of neurotransmitters from synaptic vesicles much faster: in a 10th of a millisecond. We propose that, similar to the case of muscle myosins, the ultrafast fusion results from cooperative action of many SNAREpins. The coupling originates from mechanical interactions induced by confining scaffolds. Each SNAREpin is known to have enough energy to overcome the fusion barrier of 25-[Formula: see text]; however, the fusion barrier only becomes relevant when the SNAREpins are nearly completely zippered, and from this state, each SNAREpin can deliver only a small fraction of this energy as mechanical work. Therefore, they have to act cooperatively, and we show that at least three of them are needed to ensure fusion in less than a millisecond. However, to reach the prefusion state collectively, starting from the experimentally observed half-zippered metastable state, the SNAREpins have to mechanically synchronize, which takes more time as the number of SNAREpins increases. Incorporating this somewhat counterintuitive idea in a simple coarse-grained model results in the prediction that there should be an optimum number of SNAREpins for submillisecond fusion: three to six over a wide range of parameters. Interestingly, in situ cryoelectron microscope tomography has very recently shown that exactly six SNAREpins participate in the fusion of each synaptic vesicle. This number is in the range predicted by our theory.
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Affiliation(s)
- Fabio Manca
- Laboratoire de Physique de l'Ecole Normale Supérieure (LPENS), CNRS, Ecole Normale Supérieure, 75005 Paris, France
- LPENS, Sorbonne Université, 75005 Paris, France
- LPENS, Université Paris-Diderot, 75005 Paris, France
- LPENS, Université PSL, 75005 Paris, France
| | - Frederic Pincet
- Laboratoire de Physique de l'Ecole Normale Supérieure (LPENS), CNRS, Ecole Normale Supérieure, 75005 Paris, France
- LPENS, Sorbonne Université, 75005 Paris, France
- LPENS, Université Paris-Diderot, 75005 Paris, France
- LPENS, Université PSL, 75005 Paris, France
| | - Lev Truskinovsky
- Physique et Mécanique des Milieux Hétérogènes, CNRS, Ecole Supérieure de Physique et de Chimie Industrielles, Université PSL, 75231 Paris Cedex 05, France
| | - James E Rothman
- Department of Cell Biology, Yale University, New Haven, CT 06520;
- Department of Experimental Epilepsy, Institute of Neurology, University College London, London WC1E 6BT, United Kingdom
| | - Lionel Foret
- Laboratoire de Physique de l'Ecole Normale Supérieure (LPENS), CNRS, Ecole Normale Supérieure, 75005 Paris, France
- LPENS, Sorbonne Université, 75005 Paris, France
- LPENS, Université Paris-Diderot, 75005 Paris, France
- LPENS, Université PSL, 75005 Paris, France
| | - Matthieu Caruel
- Modélisation et Simulation Multi-Echelle, CNRS, Université Paris-Est Créteil, 94010 Créteil Cedex, France
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24
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McDargh ZA, Polley A, O'Shaughnessy B. SNARE-mediated membrane fusion is a two-stage process driven by entropic forces. FEBS Lett 2018; 592:3504-3515. [PMID: 30346036 DOI: 10.1002/1873-3468.13277] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 10/17/2018] [Accepted: 10/18/2018] [Indexed: 11/08/2022]
Abstract
SNARE proteins constitute the core of the exocytotic membrane fusion machinery. Fusion occurs when vesicle-associated and target membrane-associated SNAREs zipper into trans-SNARE complexes ('SNAREpins'), but the number required is controversial and the mechanism of cooperative fusion is poorly understood. We developed a highly coarse-grained molecular dynamics simulation to access the long fusion timescales, which revealed a two-stage process. First, zippering energy was dissipated and cooperative entropic forces assembled the SNAREpins into a ring; second, entropic forces expanded the ring, pressing membranes together and catalyzing fusion. We predict that any number of SNAREs fuses membranes, but fusion is faster with more SNAREs.
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Affiliation(s)
- Zachary A McDargh
- Department of Chemical Engineering, Columbia University, New York City, NY, USA
| | - Anirban Polley
- Department of Chemical Engineering, Columbia University, New York City, NY, USA
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York City, NY, USA
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25
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Karatekin E. Toward a unified picture of the exocytotic fusion pore. FEBS Lett 2018; 592:3563-3585. [PMID: 30317539 PMCID: PMC6353554 DOI: 10.1002/1873-3468.13270] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/30/2018] [Accepted: 10/10/2018] [Indexed: 11/07/2022]
Abstract
Neurotransmitter and hormone release involve calcium-triggered fusion of a cargo-loaded vesicle with the plasma membrane. The initial connection between the fusing membranes, called the fusion pore, can evolve in various ways, including rapid dilation to allow full cargo release, slow expansion, repeated opening-closing and resealing. Pore dynamics determine the kinetics of cargo release and the mode of vesicle recycling, but how these processes are controlled is poorly understood. Previous reconstitutions could not monitor single pores, limiting mechanistic insight they could provide. Recently developed nanodisc-based fusion assays allow reconstitution and monitoring of single pores with unprecedented detail and hold great promise for future discoveries. They recapitulate various aspects of exocytotic fusion pores, but comparison is difficult because different approaches suggested very different exocytotic fusion pore properties, even for the same cell type. In this Review, I discuss how most of the data can be reconciled, by recognizing how different methods probe different aspects of the same fusion process. The resulting picture is that fusion pores have broadly distributed properties arising from stochastic processes which can be modulated by physical constraints imposed by proteins, lipids and membranes.
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Affiliation(s)
- Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Nanobiology Institute, Yale University, West Haven, CT, USA
- Centre National de la Recherche Scientifique (CNRS), Paris, France
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Synergistic control of neurotransmitter release by different members of the synaptotagmin family. Curr Opin Neurobiol 2018; 51:154-162. [DOI: 10.1016/j.conb.2018.05.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 05/19/2018] [Accepted: 05/21/2018] [Indexed: 01/06/2023]
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Controlling of glutamate release by neuregulin3 via inhibiting the assembly of the SNARE complex. Proc Natl Acad Sci U S A 2018; 115:2508-2513. [PMID: 29463705 DOI: 10.1073/pnas.1716322115] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Neuregulin3 (NRG3) is a growth factor of the neuregulin (NRG) family and a risk gene of various severe mental illnesses including schizophrenia, bipolar disorders, and major depression. However, the physiological function of NRG3 remains poorly understood. Here we show that loss of Nrg3 in GFAP-Nrg3f/f mice increased glutamatergic transmission, but had no effect on GABAergic transmission. These phenotypes were observed in Nex-Nrg3f/f mice, where Nrg3 was specifically knocked out in pyramidal neurons, indicating that Nrg3 regulates glutamatergic transmission by a cell-autonomous mechanism. Consequently, in the absence of Nrg3 in pyramidal neurons, mutant mice displayed various behavioral deficits related to mental illnesses. We show that the Nrg3 mutation decreased paired-pulse facilitation, increased decay of NMDAR currents when treated with MK801, and increased minimal stimulation-elicited response, providing evidence that the Nrg3 mutation increases glutamate release probability. Notably, Nrg3 is a presynaptic protein that regulates the SNARE-complex assembly. Finally, increased Nrg3 levels, as observed in patients with severe mental illnesses, suppressed glutamatergic transmission. Together, these observations indicate that, unlike the prototype Nrg1, the effect of which is mediated by activating ErbB4 in interneurons, Nrg3 is critical in controlling glutamatergic transmission by regulating the SNARE complex at the presynaptic terminals, identifying a function of Nrg3 and revealing a pathophysiological mechanism for hypofunction of the glutamatergic pathway in Nrg3-related severe mental illnesses.
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28
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Walter AM, Böhme MA, Sigrist SJ. Vesicle release site organization at synaptic active zones. Neurosci Res 2017; 127:3-13. [PMID: 29275162 DOI: 10.1016/j.neures.2017.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 12/04/2017] [Accepted: 12/06/2017] [Indexed: 11/30/2022]
Abstract
Information transfer between nerve cells (neurons) forms the basis of behavior, emotion, and survival. Signal transduction from one neuron to another occurs at synapses, and relies on both electrical and chemical signal propagation. At chemical synapses, incoming electrical action potentials trigger the release of chemical neurotransmitters that are sensed by the connected cell and here reconverted to an electrical signal. The presynaptic conversion of an electrical to a chemical signal is an energy demanding, highly regulated process that relies on a complex, evolutionarily conserved molecular machinery. Here, we review the biophysical characteristics of this process, the current knowledge of the molecules operating in this reaction and genetic specializations that may have evolved to shape inter-neuronal signaling.
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Affiliation(s)
- Alexander M Walter
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany.
| | - Mathias A Böhme
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, Berlin 13125, Germany
| | - Stephan J Sigrist
- Freie Universität Berlin, Institute for Biology/Genetics, Takustraße 6, 14195 Berlin, Germany; NeuroCure, Cluster of Excellence, Charité Universitätsmedizin, Charitéplatz 1, 10117 Berlin, Germany.
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29
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Reddy-Alla S, Böhme MA, Reynolds E, Beis C, Grasskamp AT, Mampell MM, Maglione M, Jusyte M, Rey U, Babikir H, McCarthy AW, Quentin C, Matkovic T, Bergeron DD, Mushtaq Z, Göttfert F, Owald D, Mielke T, Hell SW, Sigrist SJ, Walter AM. Stable Positioning of Unc13 Restricts Synaptic Vesicle Fusion to Defined Release Sites to Promote Synchronous Neurotransmission. Neuron 2017; 95:1350-1364.e12. [DOI: 10.1016/j.neuron.2017.08.016] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 05/10/2017] [Accepted: 08/09/2017] [Indexed: 12/24/2022]
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30
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Entropic forces drive self-organization and membrane fusion by SNARE proteins. Proc Natl Acad Sci U S A 2017; 114:5455-5460. [PMID: 28490503 DOI: 10.1073/pnas.1611506114] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SNARE proteins are the core of the cell's fusion machinery and mediate virtually all known intracellular membrane fusion reactions on which exocytosis and trafficking depend. Fusion is catalyzed when vesicle-associated v-SNAREs form trans-SNARE complexes ("SNAREpins") with target membrane-associated t-SNAREs, a zippering-like process releasing ∼65 kT per SNAREpin. Fusion requires several SNAREpins, but how they cooperate is unknown and reports of the number required vary widely. To capture the collective behavior on the long timescales of fusion, we developed a highly coarse-grained model that retains key biophysical SNARE properties such as the zippering energy landscape and the surface charge distribution. In simulations the ∼65-kT zippering energy was almost entirely dissipated, with fully assembled SNARE motifs but uncomplexed linker domains. The SNAREpins self-organized into a circular cluster at the fusion site, driven by entropic forces that originate in steric-electrostatic interactions among SNAREpins and membranes. Cooperative entropic forces expanded the cluster and pulled the membranes together at the center point with high force. We find that there is no critical number of SNAREs required for fusion, but instead the fusion rate increases rapidly with the number of SNAREpins due to increasing entropic forces. We hypothesize that this principle finds physiological use to boost fusion rates to meet the demanding timescales of neurotransmission, exploiting the large number of v-SNAREs available in synaptic vesicles. Once in an unfettered cluster, we estimate ≥15 SNAREpins are required for fusion within the ∼1-ms timescale of neurotransmitter release.
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31
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Wu Z, Bello OD, Thiyagarajan S, Auclair SM, Vennekate W, Krishnakumar SS, O'Shaughnessy B, Karatekin E. Dilation of fusion pores by crowding of SNARE proteins. eLife 2017; 6. [PMID: 28346138 PMCID: PMC5404929 DOI: 10.7554/elife.22964] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/26/2017] [Indexed: 01/29/2023] Open
Abstract
Hormones and neurotransmitters are released through fluctuating exocytotic fusion pores that can flicker open and shut multiple times. Cargo release and vesicle recycling depend on the fate of the pore, which may reseal or dilate irreversibly. Pore nucleation requires zippering between vesicle-associated v-SNAREs and target membrane t-SNAREs, but the mechanisms governing the subsequent pore dilation are not understood. Here, we probed the dilation of single fusion pores using v-SNARE-reconstituted ~23-nm-diameter discoidal nanolipoprotein particles (vNLPs) as fusion partners with cells ectopically expressing cognate, 'flipped' t-SNAREs. Pore nucleation required a minimum of two v-SNAREs per NLP face, and further increases in v-SNARE copy numbers did not affect nucleation rate. By contrast, the probability of pore dilation increased with increasing v-SNARE copies and was far from saturating at 15 v-SNARE copies per face, the NLP capacity. Our experimental and computational results suggest that SNARE availability may be pivotal in determining whether neurotransmitters or hormones are released through a transient ('kiss and run') or an irreversibly dilating pore (full fusion).
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Affiliation(s)
- Zhenyong Wu
- Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, United States.,Nanobiology Institute, Yale University, West Haven, United States
| | - Oscar D Bello
- Nanobiology Institute, Yale University, West Haven, United States.,Department of Cell Biology, School of Medicine, Yale University, New Haven, United States
| | | | - Sarah Marie Auclair
- Nanobiology Institute, Yale University, West Haven, United States.,Department of Cell Biology, School of Medicine, Yale University, New Haven, United States
| | - Wensi Vennekate
- Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, United States.,Nanobiology Institute, Yale University, West Haven, United States
| | - Shyam S Krishnakumar
- Nanobiology Institute, Yale University, West Haven, United States.,Department of Cell Biology, School of Medicine, Yale University, New Haven, United States
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, United States
| | - Erdem Karatekin
- Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, United States.,Nanobiology Institute, Yale University, West Haven, United States.,Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.,Laboratoire de Neurophotonique, Université Paris Descartes, Faculté des Sciences Fondamentales et Biomédicales, Centre National de la Recherche Scientifique, Paris, France
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32
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Diseases of the Synaptic Vesicle: A Potential New Group of Neurometabolic Disorders Affecting Neurotransmission. Semin Pediatr Neurol 2016; 23:306-320. [PMID: 28284392 DOI: 10.1016/j.spen.2016.11.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The general concept of inborn error of metabolism is currently evolving into the interface between classical biochemistry and cellular biology. Basic neuroscience is providing increasing knowledge about the mechanisms of neurotransmission and novel related disorders are being described. There is a necessity of updating the classic concept of "inborn error of neurotransmitters (NT)" that considers mainly defects of synthesis and catabolism and transport of low weight NT molecules. Monogenic defects of the synaptic vesicle (SV), and especially those affecting the SV cycle are a potential new group of NT disorders since they end up in abnormal NT turnover and release. The most common clinical manifestations include epilepsy, intellectual disability, autism and movement disorders, and are in the continuum symptoms of synaptopathies. Interestingly, brain malformations and neurodegenerative conditions are also present within SV diseases. Metabolomics, proteomics, and other -omic techniques probably will provide biomarkers and contribute to therapeutic targets in the future.
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33
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Tarafdar PK, Chakraborty H, Bruno MJ, Lentz BR. Phosphatidylserine-Dependent Catalysis of Stalk and Pore Formation by Synaptobrevin JMR-TMD Peptide. Biophys J 2016; 109:1863-72. [PMID: 26536263 DOI: 10.1016/j.bpj.2015.08.051] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 08/16/2015] [Accepted: 08/26/2015] [Indexed: 12/18/2022] Open
Abstract
Although the importance of a SNARE complex in neurotransmitter release is widely accepted, there exist different views on how the complex promotes fusion. One hypothesis is that the SNARE complex's ability to bring membranes into contact is sufficient for fusion, another points to possible roles of juxtamembrane regions (JMRs) and transmembrane domains (TMDs) in catalyzing lipid rearrangement, and another notes the complex's presumed ability to bend membranes near the point of contact. Here, we performed experiments with highly curved vesicles brought into contact using low concentrations of polyethylene glycol (PEG) to investigate the influence of the synaptobrevin (SB) TMD with an attached JMR (SB-JMR-TMD) on the rates of stalk and pore formation during vesicle fusion. SB-JMR-TMD enhanced the rates of stalk and fusion pore (FP) formation in a sharply sigmoidal fashion. We observed an optimal influence at an average of three peptides per vesicle, but only with phosphatidylserine (PS)-containing vesicles. Approximately three SB-JMR-TMDs per vesicle optimally ordered the bilayer interior and excluded water in a similar sigmoidal fashion. The catalytic influences of hexadecane and SB-JMR-TMD on fusion kinetics showed little in common, suggesting different mechanisms. Both kinetic and membrane structure measurements support the hypotheses that SB-JMR-TMD 1) catalyzes initial intermediate formation as a result of its basic JMR disrupting ordered interbilayer water and permitting closer interbilayer approach, and 2) catalyzes pore formation by forming a membrane-spanning complex that increases curvature stress at the circumference of the hemifused diaphragm of the prepore intermediate state.
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Affiliation(s)
- Pradip K Tarafdar
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Hirak Chakraborty
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Michael J Bruno
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Barry R Lentz
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Molecular and Cellular Biophysics Program, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
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34
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Körber C, Kuner T. Molecular Machines Regulating the Release Probability of Synaptic Vesicles at the Active Zone. Front Synaptic Neurosci 2016; 8:5. [PMID: 26973506 PMCID: PMC4773589 DOI: 10.3389/fnsyn.2016.00005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/17/2016] [Indexed: 11/13/2022] Open
Abstract
The fusion of synaptic vesicles (SVs) with the plasma membrane of the active zone (AZ) upon arrival of an action potential (AP) at the presynaptic compartment is a tightly regulated probabilistic process crucial for information transfer. The probability of a SV to release its transmitter content in response to an AP, termed release probability (Pr), is highly diverse both at the level of entire synapses and individual SVs at a given synapse. Differences in Pr exist between different types of synapses, between synapses of the same type, synapses originating from the same axon and even between different SV subpopulations within the same presynaptic terminal. The Pr of SVs at the AZ is set by a complex interplay of different presynaptic properties including the availability of release-ready SVs, the location of the SVs relative to the voltage-gated calcium channels (VGCCs) at the AZ, the magnitude of calcium influx upon arrival of the AP, the buffering of calcium ions as well as the identity and sensitivity of the calcium sensor. These properties are not only interconnected, but can also be regulated dynamically to match the requirements of activity patterns mediated by the synapse. Here, we review recent advances in identifying molecules and molecular machines taking part in the determination of vesicular Pr at the AZ.
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Affiliation(s)
- Christoph Körber
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute of Anatomy and Cell Biology, Heidelberg University Heidelberg, Germany
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35
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Fortoul N, Singh P, Hui CY, Bykhovskaia M, Jagota A. Coarse-Grained Model of SNARE-Mediated Docking. Biophys J 2016; 108:2258-69. [PMID: 25954883 DOI: 10.1016/j.bpj.2015.03.053] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 03/24/2015] [Accepted: 03/24/2015] [Indexed: 12/11/2022] Open
Abstract
Synaptic transmission requires that vesicles filled with neurotransmitter molecules be docked to the plasma membrane by the SNARE protein complex. The SNARE complex applies attractive forces to overcome the long-range repulsion between the vesicle and membrane. To understand how the balance between the attractive and repulsive forces defines the equilibrium docked state we have developed a model that combines the mechanics of vesicle/membrane deformation with an apparently new coarse-grained model of the SNARE complex. The coarse-grained model of the SNARE complex is calibrated by comparison with all-atom molecular dynamics simulations as well as by force measurements in laser tweezer experiments. The model for vesicle/membrane interactions includes the forces produced by membrane deformation and hydration or electrostatic repulsion. Combining these two parts, the coarse-grained model of the SNARE complex with membrane mechanics, we study how the equilibrium docked state varies with the number of SNARE complexes. We find that a single SNARE complex is able to bring a typical synaptic vesicle to within a distance of ∼ 3 nm from the membrane. Further addition of SNARE complexes shortens this distance, but an overdocked state of >4-6 SNAREs actually increases the equilibrium distance.
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Affiliation(s)
- Nicole Fortoul
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania
| | - Pankaj Singh
- Department of Mechanical & Aerospace Engineering, Cornell University, Ithaca, New York
| | - Chung-Yuen Hui
- Department of Mechanical & Aerospace Engineering, Cornell University, Ithaca, New York
| | - Maria Bykhovskaia
- Neuroscience Department, Universidad Central del Caribe, Bayamon, Puerto Rico
| | - Anand Jagota
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, Pennsylvania; Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania.
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36
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Abstract
Extensive research has yielded crucial insights into the mechanism of neurotransmitter release, and working models for the functions of key proteins involved in release. The SNAREs Syntaxin-1, Synaptobrevin, and SNAP-25 play a central role in membrane fusion, forming SNARE complexes that bridge the vesicle and plasma membranes and that are disassembled by NSF-SNAPs. Exocytosis likely starts with Syntaxin-1 folded into a self-inhibited closed conformation that binds to Munc18-1. Munc13s open Syntaxin-1, orchestrating SNARE complex assembly in an NSF-SNAP-resistant manner together with Munc18-1. In the resulting primed state, with partially assembled SNARE complexes, fusion is inhibited by Synaptotagmin-1 and Complexins, which also perform active functions in release. Upon influx of Ca(2+), Synaptotagmin-1 activates fast release, likely by relieving the inhibition caused by Complexins and cooperating with the SNAREs in bringing the membranes together. Although alternative models exist and fundamental questions remain unanswered, a definitive description of the basic release mechanism may be available soon.
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Affiliation(s)
- Josep Rizo
- Departments of Biophysics, Biochemistry, and Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390;
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37
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Nitric Oxide-Mediated Posttranslational Modifications: Impacts at the Synapse. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2016:5681036. [PMID: 26635909 PMCID: PMC4655263 DOI: 10.1155/2016/5681036] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/28/2015] [Indexed: 11/18/2022]
Abstract
Nitric oxide (NO) is an important gasotransmitter molecule that is involved in numerous physiological processes throughout the nervous system. In addition to its involvement in physiological plasticity processes (long-term potentiation, LTP; long-term depression, LTD) which can include NMDAR-mediated calcium-dependent activation of neuronal nitric oxide synthase (nNOS), new insights into physiological and pathological consequences of nitrergic signalling have recently emerged. In addition to the canonical cGMP-mediated signalling, NO is also implicated in numerous pathways involving posttranslational modifications. In this review we discuss the multiple effects of S-nitrosylation and 3-nitrotyrosination on proteins with potential modulation of function but limit the analyses to signalling involved in synaptic transmission and vesicular release. Here, crucial proteins which mediate synaptic transmission can undergo posttranslational modifications with either pre- or postsynaptic origin. During normal brain function, both pathways serve as important cellular signalling cascades that modulate a diverse array of physiological processes, including synaptic plasticity, transcriptional activity, and neuronal survival. In contrast, evidence suggests that aging and disease can induce nitrosative stress via excessive NO production. Consequently, uncontrolled S-nitrosylation/3-nitrotyrosination can occur and represent pathological features that contribute to the onset and progression of various neurodegenerative diseases, including Parkinson's, Alzheimer's, and Huntington's.
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Whittaker RG, Herrmann DN, Bansagi B, Hasan BAS, Lofra RM, Logigian EL, Sowden JE, Almodovar JL, Littleton JT, Zuchner S, Horvath R, Lochmüller H. Electrophysiologic features of SYT2 mutations causing a treatable neuromuscular syndrome. Neurology 2015; 85:1964-71. [PMID: 26519543 DOI: 10.1212/wnl.0000000000002185] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/06/2015] [Indexed: 01/27/2023] Open
Abstract
OBJECTIVES To describe the clinical and electrophysiologic features of synaptotagmin II (SYT2) mutations, a novel neuromuscular syndrome characterized by foot deformities and fatigable ocular and lower limb weakness, and the response to modulators of acetylcholine release. METHODS We performed detailed clinical and neurophysiologic assessment in 2 multigenerational families with dominant SYT2 mutations (c.920T>G [p.Asp307Ala] and c.923G>A [p.Pro308Leu]). Serial clinical and electrophysiologic assessments were performed in members of one family treated first with pyridostigmine and then with 3,4-diaminopyridine. RESULTS Electrophysiologic testing revealed features indicative of a presynaptic deficit in neurotransmitter release with posttetanic potentiation lasting up to 60 minutes. Treatment with 3,4-diaminopyridine produced both a clinical benefit and an improvement in neuromuscular transmission. CONCLUSION SYT2 mutations cause a novel and potentially treatable complex presynaptic congenital myasthenic syndrome characterized by motor neuropathy causing lower limb wasting and foot deformities, with reflex potentiation following exercise and a uniquely prolonged period of posttetanic potentiation.
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Affiliation(s)
- Roger G Whittaker
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL.
| | - David N Herrmann
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Boglarka Bansagi
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Bashar Awwad Shiekh Hasan
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Robert Muni Lofra
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Eric L Logigian
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Janet E Sowden
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Jorge L Almodovar
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - J Troy Littleton
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Stephan Zuchner
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Rita Horvath
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
| | - Hanns Lochmüller
- From the Institute of Neuroscience (R.G.W., B.A.S.H.) and John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine (B.B., R.M.L., R.H., H.L.), Newcastle University, Newcastle, UK; Department of Neurology (D.N.H., E.L.L., J.E.S.), University of Rochester Medical Center, NY; Department of Neurology (J.L.A.), Dartmouth Hitchcock Clinic, Geisel School of Medicine, Hanover, NH; The Picower Institute for Learning and Memory (J.T.L.), Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA; and Dr. John T. Macdonald Department of Human Genetics and Hussman Institute for Human Genomics (S.Z.), University of Miami, Miller School of Medicine, Miami, FL
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Takahashi N, Sawada W, Noguchi J, Watanabe S, Ucar H, Hayashi-Takagi A, Yagishita S, Ohno M, Tokumaru H, Kasai H. Two-photon fluorescence lifetime imaging of primed SNARE complexes in presynaptic terminals and β cells. Nat Commun 2015; 6:8531. [PMID: 26439845 PMCID: PMC4600761 DOI: 10.1038/ncomms9531] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 08/30/2015] [Indexed: 12/30/2022] Open
Abstract
It remains unclear how readiness for Ca(2+)-dependent exocytosis depends on varying degrees of SNARE complex assembly. Here we directly investigate the SNARE assembly using two-photon fluorescence lifetime imaging (FLIM) of Förster resonance energy transfer (FRET) between three pairs of neuronal SNAREs in presynaptic boutons and pancreatic β cells in the islets of Langerhans. These FRET probes functionally rescue their endogenous counterparts, supporting ultrafast exocytosis. We show that trans-SNARE complexes accumulated in the active zone, and estimate the number of complexes associated with each docked vesicle. In contrast, SNAREs were unassembled in resting state, and assembled only shortly prior to insulin exocytosis, which proceeds slowly. We thus demonstrate that distinct states of fusion readiness are associated with SNARE complex formation. Our FRET/FLIM approaches enable optical imaging of fusion readiness in both live and chemically fixed tissues.
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Affiliation(s)
- Noriko Takahashi
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Wakako Sawada
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Jun Noguchi
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Satoshi Watanabe
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Hasan Ucar
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Akiko Hayashi-Takagi
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Sho Yagishita
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Mitsuyo Ohno
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hiroshi Tokumaru
- Faculty of Pharmaceutical Sciences at Kagawa, Tokushima Bunri University, Kagawa 769-2193, Japan
| | - Haruo Kasai
- Faculty of Medicine, Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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40
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Hammel I, Meilijson I. Function Suggests Nano-Structure: Quantitative Structural Support for SNARE-Mediated Pore Formation. Neurotox Res 2015; 29:1-9. [PMID: 26407673 DOI: 10.1007/s12640-015-9559-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 08/22/2015] [Accepted: 08/24/2015] [Indexed: 10/23/2022]
Abstract
Granule secretory content is released in either basal or calcium-activated complete exocytosis mode. A vital element in these processes is the establishment of a fusion pore between the granule membrane and the plasma membrane, initiated by the formation of a circular rosette docking arrangement of SNARE protein complexes. The controversially disputed number of SNARE complexes needed for granule priming leading to the formation of the fusion pore, is granule-size dependent and varies between secretion modes. Resorting to a statistical mechanics approach that views SNARE complexes and Ca(2+) ions as interacting particles, we have developed a relationship that links secretion rate to SNARE rosette size, Ca(2+) concentration and Ca(2+) ion cooperativity. Data are presented and discussed which suggest this SNARE-dependent generalization of existing narrow-range biophysical models that correlate secretion rate with Ca(2+) concentration and maximal Ca(2+) ion cooperativity. Evidence from dozens of examples in the literature advocate for this relation, which holds through the entire biological range. The coalescence of so many areas of diverse research methodologies has greatly augmented our understanding of so many different sequences of granule life cycle. Accordingly, these new tools may become valuable in a variety of electrophysiological experiments.
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Affiliation(s)
- Ilan Hammel
- Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel.
| | - Isaac Meilijson
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Mathematical Sciences, Tel Aviv University, 6997801, Tel Aviv, Israel.
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41
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Koo SJ, Kochlamazashvili G, Rost B, Puchkov D, Gimber N, Lehmann M, Tadeus G, Schmoranzer J, Rosenmund C, Haucke V, Maritzen T. Vesicular Synaptobrevin/VAMP2 Levels Guarded by AP180 Control Efficient Neurotransmission. Neuron 2015; 88:330-44. [PMID: 26412491 DOI: 10.1016/j.neuron.2015.08.034] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 07/17/2015] [Accepted: 08/19/2015] [Indexed: 01/01/2023]
Abstract
Neurotransmission depends on synaptic vesicle (SV) exocytosis driven by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex formation of vesicular synaptobrevin/VAMP2 (Syb2). Exocytic fusion is followed by endocytic SV membrane retrieval and the high-fidelity reformation of SVs. Syb2 is the most abundant SV protein with 70 copies per SV, yet, one to three Syb2 molecules appear to be sufficient for basal exocytosis. Here we demonstrate that loss of the Syb2-specific endocytic adaptor AP180 causes a moderate activity-dependent reduction of vesicular Syb2 levels, defects in SV reformation, and a corresponding impairment of neurotransmission that lead to excitatory/inhibitory imbalance, epileptic seizures, and premature death. Further reduction of Syb2 levels in AP180(-/-)/Syb2(+/-) mice results in perinatal lethality, whereas Syb2(+/-) mice partially phenocopy loss of AP180, indicating that reduced vesicular Syb2 levels underlie the observed defects in neurotransmission. Thus, a large vesicular Syb2 pool maintained by AP180 is crucial to sustain efficient neurotransmission and SV reformation.
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Affiliation(s)
- Seong Joo Koo
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Gaga Kochlamazashvili
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Benjamin Rost
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Virchowweg 6, 10117 Berlin, Germany
| | - Dmytro Puchkov
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Niclas Gimber
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Martin Lehmann
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany; Freie Universität Berlin, Faculty of Biology, Chemistry and Pharmacy, 14195 Berlin, Germany
| | - Georgi Tadeus
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Jan Schmoranzer
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany; Freie Universität Berlin, Faculty of Biology, Chemistry and Pharmacy, 14195 Berlin, Germany
| | - Christian Rosenmund
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Virchowweg 6, 10117 Berlin, Germany
| | - Volker Haucke
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany; Freie Universität Berlin, Faculty of Biology, Chemistry and Pharmacy, 14195 Berlin, Germany; NeuroCure Cluster of Excellence, Charité Universitätsmedizin Berlin, Virchowweg 6, 10117 Berlin, Germany.
| | - Tanja Maritzen
- Leibniz-Institut für Molekulare Pharmakologie, Robert-Roessle-Straße 10, 13125 Berlin, Germany.
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43
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Schneggenburger R, Rosenmund C. Molecular mechanisms governing Ca2+ regulation of evoked and spontaneous release. Nat Neurosci 2015; 18:935-41. [DOI: 10.1038/nn.4044] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/09/2015] [Indexed: 12/15/2022]
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44
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GABAB receptor deficiency causes failure of neuronal homeostasis in hippocampal networks. Proc Natl Acad Sci U S A 2015; 112:E3291-9. [PMID: 26056260 DOI: 10.1073/pnas.1424810112] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Stabilization of neuronal activity by homeostatic control systems is fundamental for proper functioning of neural circuits. Failure in neuronal homeostasis has been hypothesized to underlie common pathophysiological mechanisms in a variety of brain disorders. However, the key molecules regulating homeostasis in central mammalian neural circuits remain obscure. Here, we show that selective inactivation of GABAB, but not GABA(A), receptors impairs firing rate homeostasis by disrupting synaptic homeostatic plasticity in hippocampal networks. Pharmacological GABA(B) receptor (GABA(B)R) blockade or genetic deletion of the GB(1a) receptor subunit disrupts homeostatic regulation of synaptic vesicle release. GABA(B)Rs mediate adaptive presynaptic enhancement to neuronal inactivity by two principle mechanisms: First, neuronal silencing promotes syntaxin-1 switch from a closed to an open conformation to accelerate soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly, and second, it boosts spike-evoked presynaptic calcium flux. In both cases, neuronal inactivity removes tonic block imposed by the presynaptic, GB(1a)-containing receptors on syntaxin-1 opening and calcium entry to enhance probability of vesicle fusion. We identified the GB(1a) intracellular domain essential for the presynaptic homeostatic response by tuning intermolecular interactions among the receptor, syntaxin-1, and the Ca(V)2.2 channel. The presynaptic adaptations were accompanied by scaling of excitatory quantal amplitude via the postsynaptic, GB(1b)-containing receptors. Thus, GABA(B)Rs sense chronic perturbations in GABA levels and transduce it to homeostatic changes in synaptic strength. Our results reveal a novel role for GABA(B)R as a key regulator of population firing stability and propose that disruption of homeostatic synaptic plasticity may underlie seizure's persistence in the absence of functional GABA(B)Rs.
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Südhof TC. Der molekulare Mechanismus der Neurotransmitterfreisetzung und Nervenzell-Synapsen (Nobel-Aufsatz). Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201406359] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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46
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Südhof TC. The molecular machinery of neurotransmitter release (Nobel lecture). Angew Chem Int Ed Engl 2014; 53:12696-717. [PMID: 25339369 DOI: 10.1002/anie.201406359] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Indexed: 12/18/2022]
Abstract
The most important property of synaptic transmission is its speed, which is crucial for the overall workings of the brain. In his Nobel Lecture, T. C. Südhof explains how the synaptic vesicle and the plasma membrane undergo rapid fusion during neurotransmitter release and how this process is spatially organized, such that opening of Ca(2+) -channels allows rapid translation of the entering Ca(2+) signal into a fusion event.
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Affiliation(s)
- Thomas C Südhof
- Department of Molecular and Cellular Physiology and Howard Hughes Medical Institute, Lorry Lokey SIM1 Building 07-535 Room G1021, 265 Campus Drive, Stanford University School of Medicine, CA 94305 (USA)
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