scholarly journals RIM-BP2 primes synaptic vesicles via recruitment of Munc13-1 at hippocampal mossy fiber synapses

2018 ◽  
Author(s):  
Marisa M Brockmann ◽  
Marta Maglione ◽  
Claudia G Willmes ◽  
Alexander Stumpf ◽  
A Boris Bouazza ◽  
...  
Keyword(s):  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Spatial Organization ◽  
Mossy Fiber ◽  
Strong Impact ◽  
Wild Type ◽  
Vesicle Docking ◽  
Presynaptic Protein ◽  
Determinant Factor ◽  
High Diversity

SummaryAll synapses require fusion-competent vesicles and coordinated Ca2+-secretion coupling for neurotransmission, yet functional and anatomical properties show a high diversity across different synapse types. We show here that the presynaptic protein RIM-BP2 has diversified functions in neurotransmitter release at different central mammalian 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 strong impact on neurotransmitter release by promoting vesicle docking/priming via recruitment of Munc13-1. In wild type mossy fiber synapses, the distance between RIM-BP2 clusters and Munc13-1 clusters is larger than in hippocampal pyramidal CA3-CA1 synapses, suggesting that spatial 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.

scholarly journals RIM-BP2 primes synaptic vesicles via recruitment of Munc13-1 at hippocampal mossy fiber synapses

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Marisa M Brockmann ◽  
Marta Maglione ◽  
Claudia G Willmes ◽  
Alexander Stumpf ◽  
Boris A Bouazza ◽  
...  
Keyword(s):  
Active Zone ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Mossy Fiber ◽  
Substantial Impact ◽  
Vesicle Docking ◽  
Vesicular Release ◽  
Anatomical Properties ◽  
Presynaptic Protein ◽  
Determinant Factor

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.

scholarly journals Vesicle-associated membrane protein-2 (synaptobrevin-2) forms a complex with synaptophysin

1995 ◽  
Vol 305 (3) ◽  
pp. 721-724 ◽  
Author(s):  
P Washbourne ◽  
G Schiavo ◽  
C Montecucco
Keyword(s):  
Membrane Protein ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Cross Linking ◽  
Type Ii ◽  
Presynaptic Membrane ◽  
Terminal Part ◽  
Vesicle Docking ◽  
Botulinum Neurotoxins ◽  
Type Ii Membrane Protein

Vesicle-associated membrane protein (VAMP) (or synaptobrevin), a type II membrane protein of small synaptic vesicles, is essential for neuroexocytosis because its proteolysis by tetanus and botulinum neurotoxins types B, D, F and G blocks neurotransmitter release. The addition of cross-linking reagents to isolated small synaptic vesicles induces the formation of 30 and 50 kDa complexes containing the isoform 2 of VAMP (VAMP-2). Whereas the 30 kDa band is a VAMP-2 homodimer, the 50 kDa species results from the cross-linking of VAMP-2 with synaptophysin. This heterodimer also forms in detergent-solubilized vesicles and involves the N-terminal part of VAMP-2. The implications of the existence of a synaptophysin-VAMP-2 complex in the processes of vesicle docking and fusion with the presynaptic membrane are discussed.

scholarly journals Regulation of a subset of release-ready vesicles by the presynaptic protein Mover

2021 ◽  
Vol 118 (3) ◽  
pp. e2022551118
Author(s):  
Ermis Pofantis ◽  
Erwin Neher ◽  
Thomas Dresbach
Keyword(s):  
Synaptic Vesicles ◽  
Wild Type ◽  
Short Term ◽  
Calyx Of Held ◽  
Short Term Plasticity ◽  
Release Probability ◽  
Pulse Ratio ◽  
Vesicular Release ◽  
Evolutionarily Conserved ◽  
Presynaptic Protein

Neurotransmitter release occurs by regulated exocytosis from synaptic vesicles (SVs). Evolutionarily conserved proteins mediate the essential aspects of this process, including the membrane fusion step and priming steps that make SVs release-competent. Unlike the proteins constituting the core fusion machinery, the SV protein Mover does not occur in all species and all synapses. Its restricted expression suggests that Mover may modulate basic aspects of transmitter release and short-term plasticity. To test this hypothesis, we analyzed synaptic transmission electrophysiologically at the mouse calyx of Held synapse in slices obtained from wild-type mice and mice lacking Mover. Spontaneous transmission was unaffected, indicating that the basic release machinery works in the absence of Mover. Evoked release and vesicular release probability were slightly reduced, and the paired pulse ratio was increased in Mover knockout mice. To explore whether Mover’s role is restricted to certain subpools of SVs, we analyzed our data in terms of two models of priming. A model assuming two SV pools in parallel showed a reduced release probability of so-called “superprimed vesicles” while “normally primed” ones were unaffected. For the second model, which holds that vesicles transit sequentially from a loosely docked state to a tightly docked state before exocytosis, we found that knocking out Mover selectively decreased the release probability of tight state vesicles. These results indicate that Mover regulates a subclass of primed SVs in the mouse calyx of Held.

scholarly journals Calcium dependence of neurotransmitter release at a high fidelity synapse

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Abdelmoneim Eshra ◽  
Hartmut Schmidt ◽  
Jens Eilers ◽  
Stefan Hallermann
Keyword(s):  
High Frequency ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Mossy Fiber ◽  
High Fidelity ◽  
Technical Challenge ◽  
Fundamental Parameters ◽  
High Affinity ◽  
Vesicle Pools ◽  
Intracellular Ca

The Ca2+-dependence of the priming, fusion, and replenishment of synaptic vesicles are fundamental parameters controlling neurotransmitter release and synaptic plasticity. Despite intense efforts, these important steps in the synaptic vesicles’ cycle remain poorly understood due to the technical challenge in disentangling vesicle priming, fusion, and replenishment. Here, we investigated the Ca2+-sensitivity of these steps at mossy fiber synapses in the rodent cerebellum, which are characterized by fast vesicle replenishment mediating high-frequency signaling. We found that the basal free Ca2+ concentration (<200 nM) critically controls action potential-evoked release, indicating a high-affinity Ca2+ sensor for vesicle priming. Ca2+ uncaging experiments revealed a surprisingly shallow and non-saturating relationship between release rate and intracellular Ca2+ concentration up to 50 μM. The rate of vesicle replenishment during sustained elevated intracellular Ca2+ concentration exhibited little Ca2+-dependence. Finally, quantitative mechanistic release schemes with five Ca2+ binding steps incorporating rapid vesicle replenishment via parallel or sequential vesicle pools could explain our data. We thus show that co-existing high- and low-affinity Ca2+ sensors mediate priming, fusion, and replenishment of synaptic vesicles at a high-fidelity synapse.

scholarly journals Calcium dependence of neurotransmitter release at a high fidelity synapse

2021 ◽  
Author(s):  
Abdelmoneim Eshra ◽  
Hartmut Schmidt ◽  
Jens Eilers ◽  
Stefan Hallermann
Keyword(s):  
Synaptic Plasticity ◽  
Release Rate ◽  
High Frequency ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Mossy Fiber ◽  
High Fidelity ◽  
Fundamental Parameters ◽  
High Affinity ◽  
Vesicle Pools

The Ca2+-dependence of the recruitment, priming, and fusion of synaptic vesicles are fundamental parameters controlling neurotransmitter release and synaptic plasticity. Despite intense efforts, these important steps in the synaptic vesicles cycle remain poorly understood because disentangling recruitment, priming, and fusion of vesicles is technically challenging. Here, we investigated the Ca2+-sensitivity of these steps at cerebellar mossy fiber synapses, which are characterized by fast vesicle recruitment mediating high-frequency signaling. We found that the basal free Ca2+ concentration (<200 nM) critically controls action potential-evoked release, indicating a high-affinity Ca2+ sensor for vesicle priming. Ca2+ uncaging experiments revealed a surprisingly shallow and non-saturating relationship between release rate and intracellular Ca2+ concentration up to 50 μM. Sustained vesicle recruitment was Ca2+-independent. Finally, quantitative mechanistic release schemes with five Ca2+ binding steps incorporating rapid vesicle recruitment via parallel or sequential vesicle pools could explain our data. We thus show that co-existing high and low-affinity Ca2+ sensors mediate recruitment, priming, and fusion of synaptic vesicles at a high-fidelity synapse.

scholarly journals A CACNA1A variant associated with trigeminal neuralgia alters the gating of Cav2.1 channels

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Eder Gambeta ◽  
Maria A. Gandini ◽  
Ivana A. Souza ◽  
Laurent Ferron ◽  
Gerald W. Zamponi
Keyword(s):  
Trigeminal Neuralgia ◽  
Missense Mutation ◽  
Neurotransmitter Release ◽  
Trigeminal System ◽  
Wild Type ◽  
Calcium Dependent ◽  
Whole Cell Patch Clamp ◽  
C Terminus ◽  
Dependent Inactivation

AbstractA novel missense mutation in the CACNA1A gene that encodes the pore forming α1 subunit of the CaV2.1 voltage-gated calcium channel was identified in a patient with trigeminal neuralgia. This mutation leads to a substitution of proline 2455 by histidine (P2455H) in the distal C-terminus region of the channel. Due to the well characterized role of this channel in neurotransmitter release, our aim was to characterize the biophysical properties of the P2455H variant in heterologously expressed CaV2.1 channels. Whole-cell patch clamp recordings of wild type and mutant CaV2.1 channels expressed in tsA-201 cells reveal that the mutation mediates a depolarizing shift in the voltage-dependence of activation and inactivation. Moreover, the P2455H mutant strongly reduced calcium-dependent inactivation of the channel that is consistent with an overall gain of function. Hence, the P2455H CaV2.1 missense mutation alters the gating properties of the channel, suggesting that associated changes in CaV2.1-dependent synaptic communication in the trigeminal system may contribute to the development of trigeminal neuralgia.

scholarly journals Inhibition of Vesicular Secretion in Both Neuronal and Nonneuronal Cells by a Retargeted Endopeptidase Derivative ofClostridium botulinum Neurotoxin Type A

2000 ◽  
Vol 68 (5) ◽  
pp. 2587-2593 ◽  
Author(s):  
John A. Chaddock ◽  
John R. Purkiss ◽  
Lorna M. Friis ◽  
Janice D. Broadbridge ◽  
Michael J. Duggan ◽  
...  
Keyword(s):  
Neurotransmitter Release ◽  
Botulinum Neurotoxin ◽  
Type A ◽  
Cell Types ◽  
Snare Complex ◽  
Cell Binding ◽  
Vesicle Docking ◽  
Botulinum Neurotoxin Type A ◽  
Clostridial Neurotoxins ◽  
Dose Dependent

ABSTRACT Clostridial neurotoxins potently and specifically inhibit neurotransmitter release in defined cell types by a mechanism that involves cleavage of specific components of the vesicle docking/fusion complex, the SNARE complex. A derivative of the type A neurotoxin fromClostridium botulinum (termed LHN/A) that retains catalytic activity can be prepared by proteolysis. The LHN/A, however, lacks the putative native binding domain (HC) of the neurotoxin and is thus unable to bind to neurons and effect inhibition of neurotransmitter release. Here we report the chemical conjugation of LHN/A to an alternative cell-binding ligand, wheat germ agglutinin (WGA). When applied to a variety of cell lines, including those that are ordinarily resistant to the effects of neurotoxin, WGA-LHN/A conjugate potently inhibits secretory responses in those cells. Inhibition of release is demonstrated to be ligand mediated and dose dependent and to occur via a mechanism involving endopeptidase-dependent cleavage of the natural botulinum neurotoxin type A substrate. These data confirm that the function of the HC domain of C. botulinumneurotoxin type A is limited to binding to cell surface moieties. The data also demonstrate that the endopeptidase and translocation functions of the neurotoxin are effective in a range of cell types, including those of nonneuronal origin. These observations lead to the conclusion that a clostridial endopeptidase conjugate that can be used to investigate SNARE-mediated processes in a variety of cells has been successfully generated.

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