Separation of presynaptic Cav2 and Cav1 channel function in synaptic vesicle exo- and endocytosis by the membrane anchored Ca2+ pump PMCA

Synaptic vesicle (SV) release, recycling, and plastic changes of release probability co-occur side by side within nerve terminals and rely on local Ca2+ signals with different temporal and spatial profiles. The mechanisms that guarantee separate regulation of these vital presynaptic functions during action potential (AP)–triggered presynaptic Ca2+ entry remain unclear. Combining Drosophila genetics with electrophysiology and imaging reveals the localization of two different voltage-gated calcium channels at the presynaptic terminals of glutamatergic neuromuscular synapses (the Drosophila Cav2 homolog, Dmca1A or cacophony, and the Cav1 homolog, Dmca1D) but with spatial and functional separation. Cav2 within active zones is required for AP-triggered neurotransmitter release. By contrast, Cav1 localizes predominantly around active zones and contributes substantially to AP-evoked Ca2+ influx but has a small impact on release. Instead, L-type calcium currents through Cav1 fine-tune short-term plasticity and facilitate SV recycling. Separate control of SV exo- and endocytosis by AP-triggered presynaptic Ca2+ influx through different channels demands efficient measures to protect the neurotransmitter release machinery against Cav1-mediated Ca2+ influx. We show that the plasma membrane Ca2+ ATPase (PMCA) resides in between active zones and isolates Cav2-triggered release from Cav1-mediated dynamic regulation of recycling and short-term plasticity, two processes which Cav2 may also contribute to. As L-type Cav1 channels also localize next to PQ-type Cav2 channels within axon terminals of some central mammalian synapses, we propose that Cav2, Cav1, and PMCA act as a conserved functional triad that enables separate control of SV release and recycling rates in presynaptic terminals.

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Drosophila Synaptotagmin 7 negatively regulates synaptic vesicle release and replenishment in a dosage-dependent manner

eLife ◽

10.7554/elife.55443 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Zhuo Guan ◽

Monica C Quiñones-Frías ◽

Yulia Akbergenova ◽

J Troy Littleton

Keyword(s):

Synaptic Vesicle ◽

Neurotransmitter Release ◽

Dependent Manner ◽

Short Term ◽

Vesicle Release ◽

Sensor Model ◽

Synaptotagmin 1 ◽

Active Zones ◽

Asynchronous Release ◽

Synaptic Vesicle Release

Synchronous neurotransmitter release is triggered by Ca2+ binding to the synaptic vesicle protein Synaptotagmin 1, while asynchronous fusion and short-term facilitation is hypothesized to be mediated by plasma membrane-localized Synaptotagmin 7 (SYT7). We generated mutations in Drosophila Syt7 to determine if it plays a conserved role as the Ca2+ sensor for these processes. Electrophysiology and quantal imaging revealed evoked release was elevated 2-fold. Syt7 mutants also had a larger pool of readily-releasable vesicles, faster recovery following stimulation, and intact facilitation. Syt1/Syt7 double mutants displayed more release than Syt1 mutants alone, indicating SYT7 does not mediate the residual asynchronous release remaining in the absence of SYT1. SYT7 localizes to an internal membrane tubular network within the peri-active zone, but does not enrich at active zones. These findings indicate the two Ca2+ sensor model of SYT1 and SYT7 mediating all phases of neurotransmitter release and facilitation is not applicable at Drosophila synapses.

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ELKS1 localizes the synaptic vesicle priming protein bMunc13-2 to a specific subset of active zones

The Journal of Cell Biology ◽

10.1083/jcb.201606086 ◽

2017 ◽

Vol 216 (4) ◽

pp. 1143-1161 ◽

Cited By ~ 18

Author(s):

Hiroshi Kawabe ◽

Miso Mitkovski ◽

Pascal S. Kaeser ◽

Johannes Hirrlinger ◽

Felipe Opazo ◽

...

Keyword(s):

Synaptic Vesicle ◽

Hippocampal Neurons ◽

Short Term ◽

Network Characteristics ◽

Short Term Plasticity ◽

Neuronal Synapses ◽

Specific Subset ◽

Specific Proteins ◽

Active Zones ◽

Essential Function

Presynaptic active zones (AZs) are unique subcellular structures at neuronal synapses, which contain a network of specific proteins that control synaptic vesicle (SV) tethering, priming, and fusion. Munc13s are core AZ proteins with an essential function in SV priming. In hippocampal neurons, two different Munc13s—Munc13-1 and bMunc13-2—mediate opposite forms of presynaptic short-term plasticity and thus differentially affect neuronal network characteristics. We found that most presynapses of cortical and hippocampal neurons contain only Munc13-1, whereas ∼10% contain both Munc13-1 and bMunc13-2. Whereas the presynaptic recruitment and activation of Munc13-1 depends on Rab3-interacting proteins (RIMs), we demonstrate here that bMunc13-2 is recruited to synapses by the AZ protein ELKS1, but not ELKS2, and that this recruitment determines basal SV priming and short-term plasticity. Thus, synapse-specific interactions of different Munc13 isoforms with ELKS1 or RIMs are key determinants of the molecular and functional heterogeneity of presynaptic AZs.

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RIM proteins and their role in synapse function

Biological Chemistry ◽

10.1515/bc.2010.064 ◽

2010 ◽

Vol 391 (6) ◽

Cited By ~ 35

Author(s):

Tobias Mittelstaedt ◽

Elena Alvaréz-Baron ◽

Susanne Schoch

Keyword(s):

Synaptic Vesicle ◽

Active Zone ◽

Neurotransmitter Release ◽

Multidomain Proteins ◽

Short Term ◽

Presynaptic Nerve Terminal ◽

Presynaptic Plasticity ◽

Active Zones ◽

Synaptic Vesicle Release ◽

The Brain

Abstract Active zones are specialized areas of the plasma membrane in the presynaptic nerve terminal that mediate neurotransmitter release and synaptic plasticity. The multidomain proteins RIM1 and RIM2 are integral components of the cytomatrix at the active zone, interacting with most other active zone-enriched proteins as well as synaptic vesicle proteins. In the brain, RIMs are present in multiple isoforms (α, β, γ) diverging in their structural composition, which mediate overlapping and distinct functions. Here, we summarize recent findings about the specific roles of the various RIM isoforms in basic synaptic vesicle release as well as long- and short-term presynaptic plasticity.

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Interplay between VGLUT Isoforms and Endophilin A1 Regulates Neurotransmitter Release and Short-Term Plasticity

Neuron ◽

10.1016/j.neuron.2011.02.002 ◽

2011 ◽

Vol 69 (6) ◽

pp. 1147-1159 ◽

Cited By ~ 59

Author(s):

Matthew C. Weston ◽

Ralf B. Nehring ◽

Sonja M. Wojcik ◽

Christian Rosenmund

Keyword(s):

Neurotransmitter Release ◽

Short Term ◽

Short Term Plasticity

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349 Intracellular calcium and short term plasticity at presynaptic terminals of the spiny lobster neuromuscular junction

Neuroscience Research ◽

10.1016/s0168-0102(97)90180-2 ◽

1997 ◽

Vol 28 ◽

pp. S69

Author(s):

Kiyoshi Ohnuma ◽

Shyunichi Ogawa ◽

Naoya Suzuki ◽

Hiromasa Kijima

Keyword(s):

Neuromuscular Junction ◽

Intracellular Calcium ◽

Spiny Lobster ◽

Short Term ◽

Presynaptic Terminals ◽

Short Term Plasticity

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Drosophila Synaptotagmin 7 negatively regulates synaptic vesicle fusion and replenishment in a dosage-dependent manner

10.1101/2020.01.30.926246 ◽

2020 ◽

Author(s):

Zhuo Guan ◽

Mónica C. Quiñones-Frías ◽

Yulia Akbergenova ◽

J. Troy Littleton

Keyword(s):

Plasma Membrane ◽

Synaptic Vesicle ◽

Active Zone ◽

Neurotransmitter Release ◽

Dependent Manner ◽

Short Term ◽

Sensor Model ◽

Synaptotagmin 1 ◽

Asynchronous Release ◽

Synaptic Vesicle Fusion

AbstractSynchronous neurotransmitter release is triggered by Ca2+ binding to the synaptic vesicle protein Synaptotagmin 1, while asynchronous fusion and short-term facilitation is hypothesized to be mediated by plasma membrane-localized Synaptotagmin 7 (SYT7). We generated mutations in Drosophila Syt7 to determine if it plays a conserved role as the Ca2+ sensor for these processes. Electrophysiology and quantal imaging revealed evoked release was elevated 2-fold. Syt7 mutants also had a larger pool of readily-releasable vesicles, faster recovery following stimulation, and robust facilitation. Syt1/Syt7 double mutants displayed more release than Syt1 mutants alone, indicating SYT7 does not mediate the residual asynchronous release remaining in the absence of SYT1. SYT7 localizes to an internal membrane tubular network within the peri-active zone, but does not enrich at release sites. These findings indicate the two Ca2+ sensor model of SYT1 and SYT7 mediating all phases of neurotransmitter release and facilitation is not applicable at Drosophila synapses.

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Reexamination of N-terminal domains of Syntaxin-1 in vesicle fusion from central murine synapses

eLife ◽

10.7554/elife.69498 ◽

2021 ◽

Vol 10 ◽

Author(s):

Gülçin Vardar ◽

Andrea Salazar-Lázaro ◽

Marisa M Brockmann ◽

Marion Weber-Boyvat ◽

Sina Zobel ◽

...

Keyword(s):

Synaptic Transmission ◽

Neurotransmitter Release ◽

Null Mouse ◽

General View ◽

Binding Modes ◽

Short Term ◽

Short Term Plasticity ◽

Open Conformation ◽

Vesicular Release ◽

Mouse Model System

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 STX'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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Synapsin Controls Both Reserve and Releasable Synaptic Vesicle Pools during Neuronal Activity and Short-Term Plasticity inAplysia

Journal of Neuroscience ◽

10.1523/jneurosci.21-12-04195.2001 ◽

2001 ◽

Vol 21 (12) ◽

pp. 4195-4206 ◽

Cited By ~ 77

Author(s):

Yann Humeau ◽

Frédéric Doussau ◽

Francesco Vitiello ◽

Paul Greengard ◽

Fabio Benfenati ◽

...

Keyword(s):

Synaptic Vesicle ◽

Neuronal Activity ◽

Short Term ◽

Short Term Plasticity ◽

Vesicle Pools

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Augmentation Controls the Fast Rebound From Depression at Excitatory Hippocampal Synapses

Journal of Neurophysiology ◽

10.1152/jn.01348.2007 ◽

2008 ◽

Vol 99 (4) ◽

pp. 1770-1786 ◽

Cited By ~ 17

Author(s):

Elizabeth Garcia-Perez ◽

John F. Wesseling

Keyword(s):

Neurotransmitter Release ◽

Single Pulse ◽

Maximal Level ◽

Short Term ◽

Paired Pulse ◽

Short Term Plasticity ◽

Readily Releasable Pool ◽

Hippocampal Synapses ◽

Low Probability ◽

Chemical Synapses

Short-term plasticity occurs at most central chemical synapses and includes both positive and negative components, but the principles governing interaction between components are largely unknown. The residual Ca2+ that persists in presynaptic terminals for several seconds after repetitive use is known to enhance neurotransmitter release under artificial, low probability of release conditions where depression is absent; this is termed augmentation. However, the full impact of augmentation under standard conditions at synapses where depression dominates is not known because of possibly complicated convolution with a variety of potential depression mechanisms. This report shows that residual Ca2+ continues to have a large enhancing impact on release at excitatory hippocampal synapses recovering from depression, including when only recently recruited vesicles are available for release. No evidence was found for gradual vesicle priming or for fast refilling of a highly releasable subdivision of the readily releasable pool (RRP). And decay of enhancement matched the clearance of residual Ca2+, thus matching the behavior of augmentation when studied in isolation. Because of incomplete RRP replenishment, synaptic strength was not typically increased above baseline when residual Ca2+ levels were highest. Instead residual Ca2+ caused single pulse release probability to rebound quickly from depression and then depress quickly during subsequent bursts of activity. Together, these observations can help resolve discrepancies in recent timing estimates of recovery from depression. Additionally, in contrast to results obtained under reduced release conditions, augmentation could be driven to a maximal level, occluding paired-pulse facilitation and other mechanisms that increase release efficiency.

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