Complexin-1 regulated transition in the assembly of single neuronal SNARE complex

Neurotransmitter release is mediated by the synaptic vesicle exocytosis. Important proteins in this process have been identified including the molecular machine Synaptic-soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins, and other regulators. Complexin (Cpx) is one of the vital regulators in this process. The functions of Cpx are proposed to maintain a proper primed vesicle pool by preventing its premature depletion, which facilitates the vesicle fusion in the presence of Ca2+. However, the molecular mechanism remains unclear. Using dual-trap optical tweezers, we detected the interaction of complexin-1 (CpxI) with SNARE. We found that the CpxI stabilizes partially folded SNARE complexes by competing with C-terminal of Vamp protein and interacting with the C-terminal of t-SNARE complex.

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SNARE Complex Oligomerization by Synaphin/Complexin Is Essential for Synaptic Vesicle Exocytosis

Cell ◽

10.1016/s0092-8674(01)00229-x ◽

2001 ◽

Vol 104 (3) ◽

pp. 421-432 ◽

Cited By ~ 111

Author(s):

Hiroshi Tokumaru ◽

Keiko Umayahara ◽

Lorenzo L Pellegrini ◽

Toru Ishizuka ◽

Hideo Saisu ◽

...

Keyword(s):

Synaptic Vesicle ◽

Snare Complex ◽

Synaptic Vesicle Exocytosis ◽

Vesicle Exocytosis

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Diurnal Changes in Exocytosis and the Number of Synaptic Ribbons at Active Zones of an on-Type Bipolar Cell Terminal

Journal of Neurophysiology ◽

10.1152/jn.00364.2006 ◽

2006 ◽

Vol 96 (4) ◽

pp. 2025-2033 ◽

Cited By ~ 50

Author(s):

Court Hull ◽

Keith Studholme ◽

Stephen Yazulla ◽

Henrique von Gersdorff

Keyword(s):

Synaptic Vesicle ◽

Bipolar Cell ◽

Bipolar Cells ◽

Synaptic Ribbons ◽

Diurnal Changes ◽

Synaptic Vesicle Exocytosis ◽

Pulse Ratio ◽

Vesicle Exocytosis ◽

Active Zones ◽

Vesicle Pool

The number and morphology of synaptic ribbons at photoreceptor and bipolar cell terminals has been reported to change on a circadian cycle. Here we sought to determine whether this phenomenon exists at goldfish Mb-type bipolar cell terminals with the aim of exploring the role of ribbons in transmitter release. We examined the physiology and ultrastructure of this terminal around two time points: midday and midnight. Nystatin perforated-patch recordings of membrane capacitance ( Cm) revealed that synaptic vesicle exocytosis evoked by short depolarizations was reduced at night, even though Ca2+ currents were larger. The efficiency of exocytosis (measured as the Δ Cm jump per total Ca2+ charge influx) was thus significantly lower at night. The paired-pulse ratio remained unchanged, however, suggesting that release probability was not altered. Hence the decreased exocytosis likely reflects a smaller readily releasable vesicle pool at night. Electron microscopy of single sections from intact retinas averaged 65% fewer ribbons at night. Interestingly, the number of active zones did not change from day to night, only the probability of finding a ribbon at an active zone. Additionally, synaptic vesicle halos surrounding the ribbons were more completely filled at night when these on-type bipolar cells are more hyperpolarized. There was no change, however, in the physical dimensions of synaptic ribbons from day to night. These results suggest that the size of the readily releasable vesicle pool and the efficiency of exocytosis are reduced at night when fewer ribbons are present at bipolar cell terminal active zones.

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Botulinum Neurotoxin a Blocks Synaptic Vesicle Exocytosis but Not Endocytosis at the Nerve Terminal

The Journal of Cell Biology ◽

10.1083/jcb.147.6.1249 ◽

1999 ◽

Vol 147 (6) ◽

pp. 1249-1260 ◽

Cited By ~ 59

Author(s):

Elaine A. Neale ◽

Linda M. Bowers ◽

Min Jia ◽

Karen E. Bateman ◽

Lura C. Williamson

Keyword(s):

Synaptic Vesicle ◽

Nerve Terminal ◽

Neurotransmitter Release ◽

Synaptic Vesicles ◽

Botulinum Neurotoxin ◽

Vesicle Membrane ◽

Botulinum Neurotoxin A ◽

Synaptic Vesicle Exocytosis ◽

Vesicle Exocytosis ◽

Botulinum Neurotoxins

The supply of synaptic vesicles in the nerve terminal is maintained by a temporally linked balance of exo- and endocytosis. Tetanus and botulinum neurotoxins block neurotransmitter release by the enzymatic cleavage of proteins identified as critical for synaptic vesicle exocytosis. We show here that botulinum neurotoxin A is unique in that the toxin-induced block in exocytosis does not arrest vesicle membrane endocytosis. In the murine spinal cord, cell cultures exposed to botulinum neurotoxin A, neither K+-evoked neurotransmitter release nor synaptic currents can be detected, twice the ordinary number of synaptic vesicles are docked at the synaptic active zone, and its protein substrate is cleaved, which is similar to observations with tetanus and other botulinal neurotoxins. In marked contrast, K+ depolarization, in the presence of Ca2+, triggers the endocytosis of the vesicle membrane in botulinum neurotoxin A–blocked cultures as evidenced by FM1-43 staining of synaptic terminals and uptake of HRP into synaptic vesicles. These experiments are the first demonstration that botulinum neurotoxin A uncouples vesicle exo- from endocytosis, and provide evidence that Ca2+ is required for synaptic vesicle membrane retrieval.

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Inositol pyrophosphates inhibit synaptotagmin-dependent exocytosis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1521600113 ◽

2016 ◽

Vol 113 (29) ◽

pp. 8314-8319 ◽

Cited By ~ 22

Author(s):

Tae-Sun Lee ◽

Joo-Young Lee ◽

Jae Won Kyung ◽

Yoosoo Yang ◽

Seung Ju Park ◽

...

Keyword(s):

Synaptic Vesicle ◽

Neurotransmitter Release ◽

Hippocampal Neurons ◽

Vesicle Fusion ◽

Synaptic Membrane ◽

Synaptic Vesicle Exocytosis ◽

Dependent Inhibition ◽

Vesicle Exocytosis ◽

Inositol Pyrophosphates

Inositol pyrophosphates such as 5-diphosphoinositol pentakisphosphate (5-IP7) are highly energetic inositol metabolites containing phosphoanhydride bonds. Although inositol pyrophosphates are known to regulate various biological events, including growth, survival, and metabolism, the molecular sites of 5-IP7 action in vesicle trafficking have remained largely elusive. We report here that elevated 5-IP7 levels, caused by overexpression of inositol hexakisphosphate (IP6) kinase 1 (IP6K1), suppressed depolarization-induced neurotransmitter release from PC12 cells. Conversely, IP6K1 depletion decreased intracellular 5-IP7 concentrations, leading to increased neurotransmitter release. Consistently, knockdown of IP6K1 in cultured hippocampal neurons augmented action potential-driven synaptic vesicle exocytosis at synapses. Using a FRET-based in vitro vesicle fusion assay, we found that 5-IP7, but not 1-IP7, exhibited significantly higher inhibitory activity toward synaptic vesicle exocytosis than IP6. Synaptotagmin 1 (Syt1), a Ca2+ sensor essential for synaptic membrane fusion, was identified as a molecular target of 5-IP7. Notably, 5-IP7 showed a 45-fold higher binding affinity for Syt1 compared with IP6. In addition, 5-IP7–dependent inhibition of synaptic vesicle fusion was abolished by increasing Ca2+ levels. Thus, 5-IP7 appears to act through Syt1 binding to interfere with the fusogenic activity of Ca2+. These findings reveal a role of 5-IP7 as a potent inhibitor of Syt1 in controlling the synaptic exocytotic pathway and expand our understanding of the signaling mechanisms of inositol pyrophosphates.

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Sphingosine Facilitates SNARE Complex Assembly and Activates Synaptic Vesicle Exocytosis

Neuron ◽

10.1016/j.neuron.2009.04.024 ◽

2009 ◽

Vol 62 (5) ◽

pp. 683-694 ◽

Cited By ~ 100

Author(s):

Frédéric Darios ◽

Catherine Wasser ◽

Anastasia Shakirzyanova ◽

Artur Giniatullin ◽

Kerry Goodman ◽

...

Keyword(s):

Synaptic Vesicle ◽

Snare Complex ◽

Complex Assembly ◽

Synaptic Vesicle Exocytosis ◽

Vesicle Exocytosis

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Diverse modes of synaptic signaling, regulation, and plasticity distinguish two classes of C. elegans glutamatergic neurons

10.1101/175836 ◽

2017 ◽

Author(s):

Donovan Ventimiglia ◽

Cornelia I. Bargmann

Keyword(s):

Synaptic Vesicle ◽

Neuronal Cell ◽

Cell Types ◽

Snare Complex ◽

C Elegans ◽

Synaptic Vesicle Exocytosis ◽

High Calcium ◽

Vesicle Exocytosis ◽

Synaptic Dynamics

AbstractSynaptic vesicle release properties vary between neuronal cell types, but in most cases the molecular basis of this heterogeneity is unknown. Here, we compare in vivo synaptic properties of two neuronal classes in the C. elegans central nervous system, using VGLUT-pHluorin to monitor synaptic vesicle exocytosis and retrieval in intact animals. We show that the glutamatergic sensory neurons AWCON and ASH have distinct synaptic dynamics associated with tonic and phasic synaptic properties, respectively. Exocytosis in ASH and AWCON is differentially affected by SNARE-complex regulators that are present in both neurons: phasic ASH release is strongly dependent on UNC-13, whereas tonic AWCON release relies upon UNC-18 and on the protein kinase C homolog PKC-1. Exocytosis and retrieval each have two timescales in AWCON but one major timescale in ASH. Strong stimuli that elicit high calcium levels also increase exocytosis and retrieval rates in AWCON, generating distinct tonic and evoked synaptic modes. These results highlight the differential deployment of shared presynaptic proteins in neuronal cell type-specific functions.

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Differential inhibition by botulinum neurotoxin A of cotransmitters released from autonomic vasodilator neurons

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2001.281.5.h2124 ◽

2001 ◽

Vol 281 (5) ◽

pp. H2124-H2132 ◽

Cited By ~ 80

Author(s):

Judy L. Morris ◽

Phillip Jobling ◽

Ian L. Gibbins

Keyword(s):

Botulinum Neurotoxin ◽

Snare Complex ◽

Snare Proteins ◽

Botulinum Neurotoxin A ◽

Uterine Arteries ◽

Synaptic Vesicle Exocytosis ◽

Protein Receptor ◽

Autonomic Neurons ◽

Vesicle Exocytosis

The role of the soluble NSF attachment protein receptor (SNARE) protein complex in release of multiple cotransmitters from autonomic vasodilator neurons was examined in isolated segments of guinea pig uterine arteries treated with botulinum neurotoxin A (BoNTA; 50 nM). Western blotting of protein extracts from uterine arteries demonstrated partial cleavage of synaptosomal-associated protein of 25 kDa (SNAP-25) to a NH2-terminal fragment of ∼24 kDa by BoNTA. BoNTA reduced the amplitude (by 70–80%) of isometric contractions of arteries in response to repeated electrical stimulation of sympathetic axons at 1 or 10 Hz. The amplitude of neurogenic relaxations mediated by neuronal nitric oxide (NO) was not affected by BoNTA, whereas the duration of peptide-mediated neurogenic relaxations to stimulation at 10 Hz was reduced (67% reduction in integrated responses). In contrast, presynaptic cholinergic inhibition of neurogenic relaxations was abolished by BoNTA. These results demonstrate that the SNARE complex has differential involvement in release of cotransmitters from the same autonomic neurons: NO release is not dependant on synaptic vesicle exocytosis, acetylcholine release from small vesicles is highly dependant on the SNARE complex, and neuropeptide release from large vesicles involves SNARE proteins that may interact differently with regulatory factors such as calcium.

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Munc13-1 MUN domain and Munc18-1 cooperatively chaperone SNARE assembly through a tetrameric complex

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1914361117 ◽

2019 ◽

Vol 117 (2) ◽

pp. 1036-1041 ◽

Cited By ~ 7

Author(s):

Tong Shu ◽

Huaizhou Jin ◽

James E. Rothman ◽

Yongli Zhang

Keyword(s):

Synaptic Vesicle ◽

Molecular Mechanism ◽

Single Molecule ◽

Neurotransmitter Release ◽

Vesicle Fusion ◽

Snare Proteins ◽

Single Molecule Force Spectroscopy ◽

Multifunctional Protein ◽

Synaptic Vesicle Fusion ◽

Template Complex

Munc13-1 is a large multifunctional protein essential for synaptic vesicle fusion and neurotransmitter release. Its dysfunction has been linked to many neurological disorders. Evidence suggests that the MUN domain of Munc13-1 collaborates with Munc18-1 to initiate SNARE assembly, thereby priming vesicles for fast calcium-triggered vesicle fusion. The underlying molecular mechanism, however, is poorly understood. Recently, it was found that Munc18-1 catalyzes neuronal SNARE assembly through an obligate template complex intermediate containing Munc18-1 and 2 SNARE proteins—syntaxin 1 and VAMP2. Here, using single-molecule force spectroscopy, we discovered that the MUN domain of Munc13-1 stabilizes the template complex by ∼2.1 kBT. The MUN-bound template complex enhances SNAP-25 binding to the templated SNAREs and subsequent full SNARE assembly. Mutational studies suggest that the MUN-bound template complex is functionally important for SNARE assembly and neurotransmitter release. Taken together, our observations provide a potential molecular mechanism by which Munc13-1 and Munc18-1 cooperatively chaperone SNARE folding and assembly, thereby regulating synaptic vesicle fusion.

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Synaptotagmin-12, a synaptic vesicle phosphoprotein that modulates spontaneous neurotransmitter release

The Journal of Cell Biology ◽

10.1083/jcb.200607021 ◽

2006 ◽

Vol 176 (1) ◽

pp. 113-124 ◽

Cited By ~ 64

Author(s):

Anton Maximov ◽

Ok-Ho Shin ◽

Xinran Liu ◽

Thomas C. Südhof

Keyword(s):

Synaptic Vesicle ◽

Neurotransmitter Release ◽

Synaptic Vesicles ◽

Spontaneous Release ◽

Dependent Protein Kinase ◽

Synaptic Vesicle Exocytosis ◽

Vesicle Exocytosis ◽

Synaptotagmin 1 ◽

Dependent Protein ◽

Central Synapses

Central synapses exhibit spontaneous neurotransmitter release that is selectively regulated by cAMP-dependent protein kinase A (PKA). We now show that synaptic vesicles contain synaptotagmin-12, a synaptotagmin isoform that differs from classical synaptotagmins in that it does not bind Ca2+. In synaptic vesicles, synaptotagmin-12 forms a complex with synaptotagmin-1 that prevents synaptotagmin-1 from interacting with SNARE complexes. We demonstrate that synaptotagmin-12 is phosphorylated by cAMP-dependent PKA on serine97, and show that expression of synaptotagmin-12 in neurons increases spontaneous neurotransmitter release by approximately threefold, but has no effect on evoked release. Replacing serine97 by alanine abolishes synaptotagmin-12 phosphorylation and blocks its effect on spontaneous release. Our data suggest that spontaneous synaptic-vesicle exocytosis is selectively modulated by a Ca2+-independent synaptotagmin isoform, synaptotagmin-12, which is controlled by cAMP-dependent phosphorylation.

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Role of C2 domain proteins during synaptic vesicle exocytosis

Biochemical Society Transactions ◽

10.1042/bst0380213 ◽

2010 ◽

Vol 38 (1) ◽

pp. 213-216 ◽

Cited By ~ 21

Author(s):

Sascha Martens

Keyword(s):

Membrane Fusion ◽

Synaptic Vesicle ◽

Synaptic Vesicles ◽

Calcium Concentration ◽

Membrane Curvature ◽

Snare Complex ◽

C2 Domain ◽

C2 Domains ◽

Synaptic Vesicle Exocytosis ◽

Vesicle Exocytosis

Neurotransmitter release is mediated by the fusion of synaptic vesicles with the presynaptic plasma membrane. Fusion is triggered by a rise in the intracellular calcium concentration and is dependent on the neuronal SNARE (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein receptor) complex. A plethora of molecules such as members of the MUNC13, MUNC18, complexin and synaptotagmin families act along with the SNARE complex to enable calcium-regulated synaptic vesicle exocytosis. The synaptotagmins are localized to synaptic vesicles by an N-terminal transmembrane domain and contain two cytoplasmic C2 domains. Members of the synaptotagmin family are thought to translate the rise in intracellular calcium concentration into synaptic vesicle fusion. The C2 domains of synaptotagmin-1 bind membranes in a calcium-dependent manner and in response induce a high degree of membrane curvature, which is required for its ability to trigger membrane fusion in vitro and in vivo. Furthermore, members of the soluble DOC2 (double-C2 domain) protein family have similar properties. Taken together, these results suggest that C2 domain proteins such as the synaptotagmins and DOC2s promote membrane fusion by the induction of membrane curvature in the vicinity of the SNARE complex. Given the widespread expression of C2 domain proteins in secretory cells, it is proposed that promotion of SNARE-dependent membrane fusion by the induction of membrane curvature is a widespread phenomenon.

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