scholarly journals Fife organizes synaptic vesicles and calcium channels for high-probability neurotransmitter release

2016 ◽  
Vol 216 (1) ◽  
pp. 231-246 ◽  
Author(s):  
Joseph J. Bruckner ◽  
Hong Zhan ◽  
Scott J. Gratz ◽  
Monica Rao ◽  
Fiona Ukken ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Motor Behavior ◽  
Molecular Organization ◽  
Electrophysiological Studies ◽  
Circuit Function ◽  
Synaptic Vesicle Release ◽  
Ca2 Channels

The strength of synaptic connections varies significantly and is a key determinant of communication within neural circuits. Mechanistic insight into presynaptic factors that establish and modulate neurotransmitter release properties is crucial to understanding synapse strength, circuit function, and neural plasticity. We previously identified Drosophila Piccolo-RIM-related Fife, which regulates neurotransmission and motor behavior through an unknown mechanism. Here, we demonstrate that Fife localizes and interacts with RIM at the active zone cytomatrix to promote neurotransmitter release. Loss of Fife results in the severe disruption of active zone cytomatrix architecture and molecular organization. Through electron tomographic and electrophysiological studies, we find a decrease in the accumulation of release-ready synaptic vesicles and their release probability caused by impaired coupling to Ca2+ channels. Finally, we find that Fife is essential for the homeostatic modulation of neurotransmission. We propose that Fife organizes active zones to create synaptic vesicle release sites within nanometer distance of Ca2+ channel clusters for reliable and modifiable neurotransmitter release.

Neurotransmitter Release

2017 ◽  
Author(s):  
Peggy Mason
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicle ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Synaptic Cleft ◽  
Fusion Pore ◽  
Synaptic Membrane ◽  
Specialized Region ◽  
Synaptic Vesicle Fusion

The biochemical and physiological processes of neurotransmitter release from an active zone, a specialized region of synaptic membrane, are examined. Synaptic vesicles containing neurotransmitters are docked at the active zone and then primed for release by SNARE complexes that bring them into extreme proximity to the plasma membrane. Entry of calcium ions through voltage-gated calcium channels triggers synaptic vesicle fusion with the synaptic terminal membrane and the consequent diffusion of neurotransmitter into the synaptic cleft. Release results when the fusion pore bridging the synaptic vesicle and plasma membrane widens and neurotransmitter from the inside of the synaptic vesicle diffuses into the synaptic cleft. Membrane from the active zone membrane is endocytosed, and synaptic vesicle proteins are then reassembled into recycled synaptic vesicles, allowing for more rounds of neurotransmitter release.

scholarly journals Role of α-SNAP in Promoting Efficient Neurotransmission at the Crayfish Neuromuscular Junction

1999 ◽  
Vol 82 (6) ◽  
pp. 3406-3416 ◽  
Author(s):  
Ping He ◽  
R. Chase Southard ◽  
Dong Chen ◽  
S. W. Whiteheart ◽  
R. L. Cooper
Keyword(s):  
Neuromuscular Junction ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Synaptic Current ◽  
Attachment Protein ◽  
Quantal Analysis ◽  
Sensitive Factor ◽  
Electrophysiological Studies ◽  
Crayfish Neuromuscular Junction

In this manuscript, we address the role of the soluble N-ethylmaleimide sensitive factor attachment protein (α-SNAP) in synaptic transmission at the neuromuscular junction of the crayfish opener muscle. Immunochemcial methods confirm the presence of α-SNAP in these preparations and show that it is concentrated in the synaptic areas. Microinjection and electrophysiological studies show that α-SNAP causes an increase in neurotransmitter release yet does not significantly affect the kinetics. More specific quantal analysis, using focal, macropatch, synaptic current recordings, shows that α-SNAP increases transmitter release by increasing the probability of exocytosis but not the number of potential release sites. These data demonstrate that the role of α-SNAP is to increase the efficiency of neurotransmission by increasing the probability that a stimulus will result in neurotransmitter release. What this suggests is that α-SNAP is critical for the formation and maintenance of a “ready release” pool of synaptic vesicles.

scholarly journals Presynaptic Calcium Channels

2019 ◽  
Vol 20 (9) ◽  
pp. 2217 ◽  
Author(s):  
Sumiko Mochida
Keyword(s):  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Neuronal Firing ◽  
Regulatory Proteins ◽  
Channel Modulation ◽  
Signaling Complex ◽  
Presynaptic Plasticity ◽  
Presynaptic Calcium ◽  
Ca2 Channels ◽  
Α1 Subunit

Presynaptic Ca2+ entry occurs through voltage-gated Ca2+ (CaV) channels which are activated by membrane depolarization. Depolarization accompanies neuronal firing and elevation of Ca2+ triggers neurotransmitter release from synaptic vesicles. For synchronization of efficient neurotransmitter release, synaptic vesicles are targeted by presynaptic Ca2+ channels forming a large signaling complex in the active zone. The presynaptic CaV2 channel gene family (comprising CaV2.1, CaV2.2, and CaV2.3 isoforms) encode the pore-forming α1 subunit. The cytoplasmic regions are responsible for channel modulation by interacting with regulatory proteins. This article overviews modulation of the activity of CaV2.1 and CaV2.2 channels in the control of synaptic strength and presynaptic plasticity.

scholarly journals Quantitative analysis of the native presynaptic cytomatrix by cryoelectron tomography

2010 ◽  
Vol 188 (1) ◽  
pp. 145-156 ◽  
Author(s):  
Rubén Fernández-Busnadiego ◽  
Benoît Zuber ◽  
Ulrike Elisabeth Maurer ◽  
Marek Cyrklaff ◽  
Wolfgang Baumeister ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Attachment Protein ◽  
Readily Releasable Pool ◽  
Protein Receptor ◽  
Membrane Contact ◽  
Synaptic Vesicle Release ◽  
Protein Attachment

The presynaptic terminal contains a complex network of filaments whose precise organization and functions are not yet understood. The cryoelectron tomography experiments reported in this study indicate that these structures play a prominent role in synaptic vesicle release. Docked synaptic vesicles did not make membrane to membrane contact with the active zone but were instead linked to it by tethers of different length. Our observations are consistent with an exocytosis model in which vesicles are first anchored by long (>5 nm) tethers that give way to multiple short tethers once vesicles enter the readily releasable pool. The formation of short tethers was inhibited by tetanus toxin, indicating that it depends on soluble N-ethyl-maleimide sensitive fusion protein attachment protein receptor complex assembly. Vesicles were extensively interlinked via a set of connectors that underwent profound rearrangements upon synaptic stimulation and okadaic acid treatment, suggesting a role of these connectors in synaptic vesicle mobilization and neurotransmitter release.

scholarly journals Maturation of active zone assembly by Drosophila Bruchpilot

2009 ◽  
Vol 186 (1) ◽  
pp. 129-145 ◽  
Author(s):  
Wernher Fouquet ◽  
David Owald ◽  
Carolin Wichmann ◽  
Sara Mertel ◽  
Harald Depner ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drosophila Melanogaster ◽  
High Resolution ◽  
Active Zone ◽  
Synaptic Vesicles ◽  
C Terminus ◽  
Family Protein ◽  
N Terminus ◽  
Dense Projections ◽  
Ca2 Channels

Synaptic vesicles fuse at active zone (AZ) membranes where Ca2+ channels are clustered and that are typically decorated by electron-dense projections. Recently, mutants of the Drosophila melanogaster ERC/CAST family protein Bruchpilot (BRP) were shown to lack dense projections (T-bars) and to suffer from Ca2+ channel–clustering defects. In this study, we used high resolution light microscopy, electron microscopy, and intravital imaging to analyze the function of BRP in AZ assembly. Consistent with truncated BRP variants forming shortened T-bars, we identify BRP as a direct T-bar component at the AZ center with its N terminus closer to the AZ membrane than its C terminus. In contrast, Drosophila Liprin-α, another AZ-organizing protein, precedes BRP during the assembly of newly forming AZs by several hours and surrounds the AZ center in few discrete punctae. BRP seems responsible for effectively clustering Ca2+ channels beneath the T-bar density late in a protracted AZ formation process, potentially through a direct molecular interaction with intracellular Ca2+ channel domains.

scholarly journals Neurotransmitter Release Site Replenishment and Presynaptic Plasticity

2020 ◽  
Vol 22 (1) ◽  
pp. 327
Author(s):  
Sumiko Mochida
Keyword(s):  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
High Speed ◽  
Release Site ◽  
Short Term ◽  
Short Term Plasticity ◽  
Multiple Protein ◽  
Presynaptic Plasticity ◽  
Presynaptic Plasma Membrane ◽  
Ca2 Channels

An action potential (AP) triggers neurotransmitter release from synaptic vesicles (SVs) docking to a specialized release site of presynaptic plasma membrane, the active zone (AZ). The AP simultaneously controls the release site replenishment with SV for sustainable synaptic transmission in response to incoming neuronal signals. Although many studies have suggested that the replenishment time is relatively slow, recent studies exploring high speed resolution have revealed SV dynamics with milliseconds timescale after an AP. Accurate regulation is conferred by proteins sensing Ca2+ entering through voltage-gated Ca2+ channels opened by an AP. This review summarizes how millisecond Ca2+ dynamics activate multiple protein cascades for control of the release site replenishment with release-ready SVs that underlie presynaptic short-term plasticity.

scholarly journals A novel region in the CaV2.1 α1 subunit C-terminus regulates fast synaptic vesicle fusion and vesicle docking at the mammalian presynaptic active zone

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Matthias Lübbert ◽  
R Oliver Goral ◽  
Rachel Satterfield ◽  
Travis Putzke ◽  
Arn MJM van den Maagdenberg ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Physical Distance ◽  
Subunit C ◽  
Vesicle Docking ◽  
C Terminus ◽  
Synaptic Vesicle Release ◽  
Synaptic Vesicle Fusion ◽  
Α1 Subunit

In central nervous system (CNS) synapses, action potential-evoked neurotransmitter release is principally mediated by CaV2.1 calcium channels (CaV2.1) and is highly dependent on the physical distance between CaV2.1 and synaptic vesicles (coupling). Although various active zone proteins are proposed to control coupling and abundance of CaV2.1 through direct interactions with the CaV2.1 α1 subunit C-terminus at the active zone, the role of these interaction partners is controversial. To define the intrinsic motifs that regulate coupling, we expressed mutant CaV2.1 α1 subunits on a CaV2.1 null background at the calyx of Held presynaptic terminal. Our results identified a region that directly controlled fast synaptic vesicle release and vesicle docking at the active zone independent of CaV2.1 abundance. In addition, proposed individual direct interactions with active zone proteins are insufficient for CaV2.1 abundance and coupling. Therefore, our work advances our molecular understanding of CaV2.1 regulation of neurotransmitter release in mammalian CNS synapses.

scholarly journals Reconstructing essential active zone functions within a synapse

2021 ◽  
Author(s):  
Chao Tan ◽  
Shan Shan H Wang ◽  
Giovanni de Nola ◽  
Pascal S Kaeser
Keyword(s):  
Fusion Protein ◽  
Synaptic Vesicle ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Molecular Machines ◽  
Vesicle Docking ◽  
Active Zones ◽  
Ca2 Channels

Active zones are molecular machines that control neurotransmitter release through synaptic vesicle docking and priming, and through coupling of these vesicles to Ca2+ entry. The complexity of active zone machinery has made it challenging to determine which mechanisms drive these roles in release. Here, we induce RIM+ELKS knockout to eliminate active zone scaffolding networks, and then reconstruct each active zone function. Re-expression of RIM1-Zn fingers positioned Munc13 on undocked vesicles and rendered them release-competent. Reconstitution of release-triggering required docking of these vesicles to Ca2+ channels. Fusing RIM1-Zn to CaVbeta4-subunits sufficed to restore docking, priming and release-triggering without reinstating active zone scaffolds. Hence, exocytotic activities of the 80 kDa CaVbeta4-Zn fusion protein bypassed the need for megadalton-sized secretory machines. These data define key mechanisms of active zone function, establish that fusion competence and docking are mechanistically separable, and reveal that active zone scaffolding networks are not required for release.

scholarly journals Physical and functional interaction of the active zone proteins, CAST, RIM1, and Bassoon, in neurotransmitter release

2004 ◽  
Vol 164 (2) ◽  
pp. 301-311 ◽  
Author(s):  
Etsuko Takao-Rikitsu ◽  
Sumiko Mochida ◽  
Eiji Inoue ◽  
Maki Deguchi-Tawarada ◽  
Marie Inoue ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Active Zone ◽  
Neurotransmitter Release ◽  
Synaptic Vesicles ◽  
Ternary Complex ◽  
Binding Region ◽  
Functional Interaction ◽  
Cervical Ganglion ◽  
Ganglion Neurons ◽  
The Brain

We have recently isolated a novel cytomatrix at the active zone (CAZ)–associated protein, CAST, and found it directly binds another CAZ protein RIM1 and indirectly binds Munc13-1 through RIM1; RIM1 and Munc13-1 directly bind to each other and are implicated in priming of synaptic vesicles. Here, we show that all the CAZ proteins thus far known form a large molecular complex in the brain, including CAST, RIM1, Munc13-1, Bassoon, and Piccolo. RIM1 and Bassoon directly bind to the COOH terminus and central region of CAST, respectively, forming a ternary complex. Piccolo, which is structurally related to Bassoon, also binds to the Bassoon-binding region of CAST. Moreover, the microinjected RIM1- or Bassoon-binding region of CAST impairs synaptic transmission in cultured superior cervical ganglion neurons. Furthermore, the CAST-binding domain of RIM1 or Bassoon also impairs synaptic transmission in the cultured neurons. These results indicate that CAST serves as a key component of the CAZ structure and is involved in neurotransmitter release by binding these CAZ proteins.

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