The Experts below are selected from a list of 18744 Experts worldwide ranked by ideXlab platform
Axel T. Brunger - One of the best experts on this subject based on the ideXlab platform.
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Synaptic Vesicle Fusion: today and beyond
Nature Structural & Molecular Biology, 2019Co-Authors: Nils Brose, Axel T. Brunger, David S. Cafiso, Edwin R. Chapman, Jiajie Diao, Frederick M. Hughson, Meyer B. Jackson, Reinhard Jahn, Manfred LindauAbstract:Researchers working on synaptic Vesicle Fusion and neurotransmitter release share their views on the most interesting developments in their field and the challenges that lie ahead.
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ca2 triggered synaptic Vesicle Fusion initiated by release of inhibition
Trends in Cell Biology, 2018Co-Authors: Axel T. Brunger, Jeremy Leitz, Qiangjun Zhou, Ucheor B Choi, Ying LaiAbstract:Recent structural and functional studies of the synaptic Vesicle Fusion machinery suggest an inhibited tripartite complex consisting of neuronal soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs), synaptotagmin, and complexin prior to Ca2+-triggered synaptic Vesicle Fusion. We speculate that Ca2+-triggered Fusion commences with the release of inhibition by Ca2+ binding to synaptotagmin C2 domains. Subsequently, Fusion is assisted by SNARE complex zippering and by active membrane remodeling properties of synaptotagmin. This additional, inhibitory role of synaptotagmin may be a general principle since other recent studies suggest that Ca2+ binding to extended synaptotagmin C2 domains enables lipid transport by releasing an inhibited state of the system, and that Munc13 may nominally be in an inhibited state, which is released upon Ca2+ binding to one of its C2 domains.
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Reconstitution of Calcium-Triggered Synaptic Vesicle Fusion
Biophysical Journal, 2013Co-Authors: Axel T. BrungerAbstract:The highly conserved SNARE protein family mediates membrane Fusion in eukaryotic cells. We recently developed an assay to study calcium triggered synaptic Vesicle Fusion using single Vesicle-Vesicle optical microscopy. Prior to calcium injection, the system starts from a metastable state of single interacting pairs of donor and acceptor Vesicles. Upon calcium injection, the system monitors content mixing (exchange or release of content) as well as lipid mixing (exchange of membrane components). Our system differentiates between Vesicle docking, hemiFusion, and complete Fusion. Events are monitored on a hundred-millisecond time scale. We found that our system with reconstituted neuronal SNAREs, synaptotagmin-1, and complexin qualitatively mimics effects of calcium-triggered fast synchronous release. New insights into the mechanism of action of calcium-triggered synaptic Vesicle Fusion will be discussed.References:Kyoung, M., Srivastava, A., Zhang, Y. X., Diao, J. J., Vrljic, M., Grob, P., Nogales, E., Chu, S., Brunger, A. T. In vitro system capable of differentiating fast Ca(2+)-triggered content mixing from lipid exchange for mechanistic studies of neurotransmitter release. Proceedings of the National Academy of Sciences of the United States of America, 108, E304-E313. (2011).Kyoung, M., Zhang, Y., Diao, J., Chu, S., & Brunger, A.T. Studying calcium triggered Vesicle Fusion in a single Vesicle content/lipid mixing system. Nature Protocols, in press (2012).Diao, J., Grob, P., Cipriano, D., Kyoung, M., Zhang, Y., Shah, S., Nguyen, A., Padolina, M., Srivastava, A., Vrljic, M., Shah, A., Nogales, E., Chu, S., Brunger, A.T. Synaptic proteins promote calcium -triggered fast transition from point contact to full Fusion. eLife, in press (2012).
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studying calcium triggered Vesicle Fusion in a single Vesicle Vesicle content and lipid mixing system
Nature Protocols, 2013Co-Authors: Minjoung Kyoung, Jiajie Diao, Yunxiang Zhang, Axel T. BrungerAbstract:Studying calcium-triggered Vesicle Fusion in a single Vesicle-Vesicle content and lipid-mixing system
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Molecular mechanism of the synaptotagmin-SNARE interaction in Ca2+-triggered Vesicle Fusion
Nature Structural & Molecular Biology, 2010Co-Authors: Marija Vrljic, R. Bryan Sutton, Pavel Strop, James A. Ernst, Steven Chu, Axel T. BrungerAbstract:The interaction between synaptotagmin and SNAREs was characterized by a combination of single-molecule FRET and crystallography. The arrangement of the two Ca2+-binding loops of synaptotagmin 3 within SNARE-induced Ca2+-bound synaptotagmin 3 matches that of SNARE-bound synaptotagmin 1, suggesting a common molecular mechanism by which the synaptotagmin–SNARE interaction plays a role in Ca2+-triggered Vesicle Fusion.
Simon Alford - One of the best experts on this subject based on the ideXlab platform.
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presynaptic g protein coupled receptors dynamically modify Vesicle Fusion synaptic cleft glutamate concentrations and motor behavior
The Journal of Neuroscience, 2009Co-Authors: Tatyana Gerachshenko, Eric Schwartz, Adam Bleckert, Huzefa Photowala, Andrew Seymour, Simon AlfordAbstract:Understanding how neuromodulators regulate behavior requires investigating their effects on functional neural systems, but also their underlying cellular mechanisms. Utilizing extensively characterized lamprey motor circuits, and the unique access to reticulospinal presynaptic terminals in the intact spinal cord that initiate these behaviors, we investigated effects of presynaptic G-protein-coupled receptors on locomotion from the systems level, to the molecular control of Vesicle Fusion. 5-HT inhibits neurotransmitter release via a Gβγ interaction with the soluble N -ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex that promotes kiss-and-run Vesicle Fusion. In the lamprey spinal cord, we demonstrate that, although presynaptic 5-HT receptors inhibit evoked neurotransmitter release from reticulospinal command neurons, their activation does not abolish locomotion but rather modulates locomotor rhythms. Liberation of presynaptic Gβγ causes substantial inhibition of AMPA receptor-mediated synaptic responses but leaves NMDA receptor-mediated components of neurotransmission mostly intact. Because Gβγ binding to the SNARE complex is displaced by Ca 2+ -synaptotagmin binding, 5-HT-mediated inhibition displays Ca 2+ sensitivity. We show that, as Ca 2+ accumulates presynaptically during physiological bouts of activity, 5-HT/Gβγ-mediated presynaptic inhibition is relieved, leading to a frequency-dependent increase in synaptic concentrations of glutamate. This frequency-dependent phenomenon mirrors a shift in the Vesicle Fusion mode and a recovery of AMPA receptor-mediated EPSCs from inhibition without a modification of NMDA receptor EPSCs. We conclude that activation of presynaptic 5-HT G-protein-coupled receptors state-dependently alters Vesicle Fusion properties to shift the weight of NMDA versus AMPA receptor-mediated responses at excitatory synapses. We have therefore identified a novel mechanism in which modification of Vesicle Fusion modes may profoundly alter locomotor behavior.
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presynaptic g protein coupled receptors regulate synaptic cleft glutamate via transient Vesicle Fusion
The Journal of Neuroscience, 2007Co-Authors: Eric Schwartz, Tatyana Gerachshenko, Trillium Blackmer, Simon AlfordAbstract:When synaptic Vesicles fuse with the plasma membrane, they may completely collapse or fuse transiently. Transiently fusing Vesicles remain structurally intact and therefore have been proposed to represent a form of rapid Vesicle recycling. However, the impact of a transient synaptic Vesicle Fusion event on neurotransmitter release, and therefore on synaptic transmission, has yet to be determined. Recently, the molecular mechanism by which a serotonergic presynaptic G-protein-coupled receptor (GPCR) regulates synaptic Vesicle Fusion and inhibits synaptic transmission was identified. By making paired electrophysiological recordings in the presence and absence of low-affinity antagonists, we now demonstrate that activation of this presynaptic GPCR lowers the peak synaptic cleft glutamate concentration independently of the probability of Vesicle Fusion. Furthermore, this change in cleft glutamate concentration differentially inhibits synaptic NMDA and AMPA receptor-mediated currents. We conclude that a presynaptic GPCR regulates the profile of glutamate in the synaptic cleft through altering the mechanism of Vesicle Fusion leading to qualitative as well as quantitative changes in neural signaling.
Eric Schwartz - One of the best experts on this subject based on the ideXlab platform.
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presynaptic g protein coupled receptors dynamically modify Vesicle Fusion synaptic cleft glutamate concentrations and motor behavior
The Journal of Neuroscience, 2009Co-Authors: Tatyana Gerachshenko, Eric Schwartz, Adam Bleckert, Huzefa Photowala, Andrew Seymour, Simon AlfordAbstract:Understanding how neuromodulators regulate behavior requires investigating their effects on functional neural systems, but also their underlying cellular mechanisms. Utilizing extensively characterized lamprey motor circuits, and the unique access to reticulospinal presynaptic terminals in the intact spinal cord that initiate these behaviors, we investigated effects of presynaptic G-protein-coupled receptors on locomotion from the systems level, to the molecular control of Vesicle Fusion. 5-HT inhibits neurotransmitter release via a Gβγ interaction with the soluble N -ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex that promotes kiss-and-run Vesicle Fusion. In the lamprey spinal cord, we demonstrate that, although presynaptic 5-HT receptors inhibit evoked neurotransmitter release from reticulospinal command neurons, their activation does not abolish locomotion but rather modulates locomotor rhythms. Liberation of presynaptic Gβγ causes substantial inhibition of AMPA receptor-mediated synaptic responses but leaves NMDA receptor-mediated components of neurotransmission mostly intact. Because Gβγ binding to the SNARE complex is displaced by Ca 2+ -synaptotagmin binding, 5-HT-mediated inhibition displays Ca 2+ sensitivity. We show that, as Ca 2+ accumulates presynaptically during physiological bouts of activity, 5-HT/Gβγ-mediated presynaptic inhibition is relieved, leading to a frequency-dependent increase in synaptic concentrations of glutamate. This frequency-dependent phenomenon mirrors a shift in the Vesicle Fusion mode and a recovery of AMPA receptor-mediated EPSCs from inhibition without a modification of NMDA receptor EPSCs. We conclude that activation of presynaptic 5-HT G-protein-coupled receptors state-dependently alters Vesicle Fusion properties to shift the weight of NMDA versus AMPA receptor-mediated responses at excitatory synapses. We have therefore identified a novel mechanism in which modification of Vesicle Fusion modes may profoundly alter locomotor behavior.
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presynaptic g protein coupled receptors regulate synaptic cleft glutamate via transient Vesicle Fusion
The Journal of Neuroscience, 2007Co-Authors: Eric Schwartz, Tatyana Gerachshenko, Trillium Blackmer, Simon AlfordAbstract:When synaptic Vesicles fuse with the plasma membrane, they may completely collapse or fuse transiently. Transiently fusing Vesicles remain structurally intact and therefore have been proposed to represent a form of rapid Vesicle recycling. However, the impact of a transient synaptic Vesicle Fusion event on neurotransmitter release, and therefore on synaptic transmission, has yet to be determined. Recently, the molecular mechanism by which a serotonergic presynaptic G-protein-coupled receptor (GPCR) regulates synaptic Vesicle Fusion and inhibits synaptic transmission was identified. By making paired electrophysiological recordings in the presence and absence of low-affinity antagonists, we now demonstrate that activation of this presynaptic GPCR lowers the peak synaptic cleft glutamate concentration independently of the probability of Vesicle Fusion. Furthermore, this change in cleft glutamate concentration differentially inhibits synaptic NMDA and AMPA receptor-mediated currents. We conclude that a presynaptic GPCR regulates the profile of glutamate in the synaptic cleft through altering the mechanism of Vesicle Fusion leading to qualitative as well as quantitative changes in neural signaling.
Ralf Schneggenburger - One of the best experts on this subject based on the ideXlab platform.
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presynaptic calcium and control of Vesicle Fusion
Current Opinion in Neurobiology, 2005Co-Authors: Ralf Schneggenburger, Erwin NeherAbstract:Vesicle Fusion and transmitter release at synapses is driven by a highly localized Ca2+ signal that rapidly builds up around open Ca2+-channels at and near presynaptic active zones. It has been difficult to estimate the amplitude and the kinetics of this 'microdomain' signal by direct Ca2+-imaging approaches. Recently, Ca2+ uncaging at large CNS synapses, among them the calyx of Held, has shown that the intrinsic cooperativity of Ca2+ in inducing Vesicle Fusion is high, with 4-5 Ca2+ ions needed to trigger Vesicle Fusion. Given the Ca2+-sensitivity of Vesicle Fusion as determined by Ca2+-uncaging, it was found that a surprisingly small (10-25 microM) and brief (<1 ms) local Ca2+ signal is sufficient to achieve the amount, and the kinetics of the physiological transmitter release. The high cooperativity of Ca2+ in inducing Vesicle Fusion and the non-saturation of the Ca2+-sensor for Vesicle Fusion renders small changes of the local Ca2+-signal highly effective in changing the release probability; an insight that is important for our understanding of short-term modulation of synaptic strength.
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allosteric modulation of the presynaptic ca2 sensor for Vesicle Fusion
Nature, 2005Co-Authors: Xuelin Lou, Volker Scheuss, Ralf SchneggenburgerAbstract:Neurotransmitter release is triggered by an increase in the cytosolic Ca2+ concentration ([Ca2+]i), but it is unknown whether the Ca2+-sensitivity of Vesicle Fusion is modulated during synaptic plasticity. We investigated whether the potentiation of neurotransmitter release by phorbol esters, which target presynaptic protein kinase C (PKC)/munc-13 signalling cascades, exerts a direct effect on the Ca2+-sensitivity of Vesicle Fusion. Using direct presynaptic Ca2+-manipulation and Ca2+ uncaging at a giant presynaptic terminal, the calyx of Held, we show that phorbol esters potentiate transmitter release by increasing the apparent Ca2+-sensitivity of Vesicle Fusion. Phorbol esters potentiate Ca2+-evoked release as well as the spontaneous release rate. We explain both effects by an increased Fusion 'willingness' in a new allosteric model of Ca2+-activation of Vesicle Fusion. In agreement with an allosteric mechanism, we observe that the classically high Ca2+ cooperativity in triggering Vesicle Fusion (approximately 4) is gradually reduced below 3 microM [Ca2+]i, reaching a value of <1 at basal [Ca2+]i. Our data indicate that spontaneous transmitter release close to resting [Ca2+]i is a consequence of an intrinsic property of the molecular machinery that mediates synaptic Vesicle Fusion.
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Allosteric modulation of the presynaptic Ca2+ sensor for Vesicle Fusion
Nature, 2005Co-Authors: Xuelin Lou, Volker Scheuss, Ralf SchneggenburgerAbstract:Neurotransmitter release is triggered by an increase in the cytosolic Ca2+ concentration ([Ca2+]i), but it is unknown whether the Ca2+-sensitivity of Vesicle Fusion is modulated during synaptic plasticity. We investigated whether the potentiation of neurotransmitter release by phorbol esters, which target presynaptic protein kinase C (PKC)/munc-13 signalling cascades, exerts a direct effect on the Ca2+-sensitivity of Vesicle Fusion. Using direct presynaptic Ca2+-manipulation and Ca2+ uncaging at a giant presynaptic terminal, the calyx of Held, we show that phorbol esters potentiate transmitter release by increasing the apparent Ca2+-sensitivity of Vesicle Fusion. Phorbol esters potentiate Ca2+-evoked release as well as the spontaneous release rate. We explain both effects by an increased Fusion 'willingness' in a new allosteric model of Ca2+-activation of Vesicle Fusion. In agreement with an allosteric mechanism, we observe that the classically high Ca2+ cooperativity in triggering Vesicle Fusion (approximately 4) is gradually reduced below 3 microM [Ca2+]i, reaching a value of
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Presynaptic calcium and control of Vesicle Fusion
Current Opinion in Neurobiology, 2005Co-Authors: Ralf Schneggenburger, Erwin NeherAbstract:Vesicle Fusion and transmitter release at synapses is driven by a highly localized Ca2+ signal that rapidly builds up around open Ca2+-channels at and near presynaptic active zones. It has been difficult to estimate the amplitude and the kinetics of this 'microdomain' signal by direct Ca2+-imaging approaches. Recently, Ca2+ uncaging at large CNS synapses, among them the calyx of Held, has shown that the intrinsic cooperativity of Ca2+ in inducing Vesicle Fusion is high, with 4-5 Ca2+ ions needed to trigger Vesicle Fusion. Given the Ca2+-sensitivity of Vesicle Fusion as determined by Ca2+-uncaging, it was found that a surprisingly small (10-25 microM) and brief (
Ying Lai - One of the best experts on this subject based on the ideXlab platform.
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ca2 triggered synaptic Vesicle Fusion initiated by release of inhibition
Trends in Cell Biology, 2018Co-Authors: Axel T. Brunger, Jeremy Leitz, Qiangjun Zhou, Ucheor B Choi, Ying LaiAbstract:Recent structural and functional studies of the synaptic Vesicle Fusion machinery suggest an inhibited tripartite complex consisting of neuronal soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs), synaptotagmin, and complexin prior to Ca2+-triggered synaptic Vesicle Fusion. We speculate that Ca2+-triggered Fusion commences with the release of inhibition by Ca2+ binding to synaptotagmin C2 domains. Subsequently, Fusion is assisted by SNARE complex zippering and by active membrane remodeling properties of synaptotagmin. This additional, inhibitory role of synaptotagmin may be a general principle since other recent studies suggest that Ca2+ binding to extended synaptotagmin C2 domains enables lipid transport by releasing an inhibited state of the system, and that Munc13 may nominally be in an inhibited state, which is released upon Ca2+ binding to one of its C2 domains.
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Phosphorylation of residues inside the SNARE complex suppresses secretory Vesicle Fusion.
The EMBO Journal, 2016Co-Authors: Seth Malmersjö, Jiajie Diao, Ying Lai, Serena Di Palma, Richard A. Pfuetzner, Austin L. Wang, Moira A. Mcmahon, Arnold Hayer, Matthew H. Porteus, Bernd BodenmillerAbstract:Abstract Membrane Fusion is essential for eukaryotic life, requiring SNARE proteins to zipper up in an α‐helical bundle to pull two membranes together. Here, we show that Vesicle Fusion can be suppressed by phosphorylation of core conserved residues inside the SNARE domain. We took a proteomics approach using a PKCB knockout mast cell model and found that the key mast cell secretory protein VAMP8 becomes phosphorylated by PKC at multiple residues in the SNARE domain. Our data suggest that VAMP8 phosphorylation reduces Vesicle Fusion in vitro and suppresses secretion in living cells, allowing Vesicles to dock but preventing Fusion with the plasma membrane. Markedly, we show that the phosphorylation motif is absent in all eukaryotic neuronal VAMPs, but present in all other VAMPs. Thus, phosphorylation of SNARE domains is a general mechanism to restrict how much cells secrete, opening the door for new therapeutic strategies for suppression of secretion.
