Complexins Regulate a Late Step in Ca2+-Dependent Neurotransmitter Release

Reim, Kerstin; Mansour, Michael; Varoqueaux, Frédérique; McMahon, Harvey T.; Südhof, Thomas C.; Brose, Nils; Rosenmund, Christian

doi:10.1016/s0092-8674(01)00192-1

Cited by 458 publications

(571 citation statements)

References 24 publications

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“…Munc18a and Munc13-1 have been shown to be "priming" factors that increase the release potential for a given population of vesicles (Ashery et al, 2000;Voets et al, 2001). Complexins are also purported to play a role in SNARE complex assembly and stabilization (Reim et al, 2001;Tokumaru et al, 2001). Though a dysfunction in any of these proteins could lead to an increase in SNARE complexes, no alterations in their levels were detected in the amygdalar kindled animals (Table 3).…”

Section: Discussionmentioning

confidence: 99%

Asymmetric accumulation of hippocampal 7S SNARE complexes occurs regardless of kindling paradigm

et al. 2007

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Modifications of neurotransmission may contribute to the synchronization of neuronal networks that are a hallmark of epileptic seizures. In this study we examine the synaptosomal proteins involved in neurotransmitter release to determine if alterations in their interactions correlate with the chronic epileptic state. Using quantitative western blotting, we measured the levels of 7S SNARE complexes and SNARE effectors in the effected hippocampi from animals that were electrically kindled through stimulation from one of three different foci. All three kindling paradigms, amygdalar, entorhinal, and septal, were associated with an accumulation of 7S SNARE complexes in the ipsilateral hippocampus, measured one month after completion of kindling. Of the eight SNARE effectors examined (α-SNAP, NSF, SV2A/B, Munc18a/nSec1, Munc13-1, Complexin 1, 2, and synaptotagmin I), there was a statistically significant bihemispheric increase of hippocampal SV2 and decrease of NSF upon kindling; neither by itself would be expected to account for the asymmetry of SNARE complex distribution. These data suggest that an ipsilateral hippocampal accumulation of SNARE complexes is a permanent alteration of kindling-induced epilepsy, regardless of stimulation pathway. The significance of these findings toward a molecular understanding of epilepsy will be discussed.

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Section: Discussionmentioning

confidence: 99%

Asymmetric accumulation of hippocampal 7S SNARE complexes occurs regardless of kindling paradigm

et al. 2007

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“…Primary antibodies and their dilutions were as follows: rabbit polyclonal antibodies against complexin (CPX)-I/II (1: 1,000; Synaptic Systems, Göttingen, Germany, #122 002, antiserum #1 raised against a conserved peptide [peptide #1, amino acids 122-134, KYLPGPLQDMFKK] and 1:2,000 -10,000, #122 103, affinity-purified antibody against peptide #2 from CPX II [peptide #2, amino acids 45-81, EEERKA-KHARMEAEREKVRQQIRDKYGLKKKEEKEAE] but recognizes both CPX I & II; Reim et al, 2001; Table 1). The CPX I/II antibodies recognized bands of the correct molecular weight on Western blots, and the bands could be selectively blocked by the antigenic peptide (Synaptic Systems product sheet).…”

Section: Antibodiesmentioning

confidence: 99%

“…Complexins are a set of small (18 -21 kDa), highly charged, cytosolic proteins that bind to the fully formed exocytotic core complex at a late step in synaptic vesicle release (McMahon et al, 1995;Reim et al, 2001;Chen et al, 2002;Pabst et al, 2002) to regulate the Ca 2ϩ -dependent triggering of transmitter exocytosis (Reim et al, 2001;Archer et al, 2002). It is thought that complexins do so by binding and stabilizing the open conformation of syntaxin in the SNARE complex (Pabst et al, 2002;Chen et al, 2002;Archer et al, 2002).…”

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confidence: 99%

Cellular distribution and subcellular localization of molecular components of vesicular transmitter release in horizontal cells of rabbit retina

Hirano

Brandstätter

Brecha

2005

J of Comparative Neurology

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The mechanism underlying transmitter release from retinal horizontal cells is poorly understood. We investigated the possibility of vesicular transmitter release from mammalian horizontal cells by examining the expression of synaptic proteins that participate in vesicular transmitter release at chemical synapses. Using immunocytochemistry, we evaluated the cellular and subcellular distribution of complexin I/II, syntaxin-1, and synapsin I in rabbit retina. Strong labeling for complexin I/II, proteins that regulate a late step in vesicular transmitter release, was found in both synaptic layers of the retina, and in somata of A-and B-type horizontal cells, of ␥-aminobutyric acid (GABA)-and glycinergic amacrine cells, and of ganglion cells. Immunoelectron microscopy demonstrated the presence of complexin I/II in horizontal cell processes postsynaptic to rod and cone ribbon synapses. Syntaxin-1, a core protein of the soluble N-ethylmaleimide-sensitive-factor attachment protein receptor (SNARE) complex known to bind to complexin, and synapsin I, a synaptic vesicle-associated protein involved in the Ca 2ϩ -dependent recruitment of synaptic vesicles for transmitter release, were also present in the horizontal cells and their processes at photoreceptor synapses. Photoreceptors and bipolar cells did not express any of these proteins at their axon terminals. The presence of complexin I/II, syntaxin-1, and synapsin I in rabbit horizontal cell processes and tips suggests that a vesicular mechanism may underlie transmitter release from mammalian horizontal cells.

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“…Although multiple approaches have revealed an essential role of complexin in synaptic fusion [7,[10][11][12][13][14][15], the nature of this role remains unclear. In vertebrate autapses, deletion of complexin selectively impairs fast synchronous neurotransmitter release without changing asynchronous or spontaneous release [7,10]. In in vitro fusion assays, conversely, addition of complexin causes a general block of SNARE-dependent fusion, indicating that complexin is a SNARE clamp [11][12][13][14].…”

mentioning

confidence: 99%

Complexin Controls the Force Transfer from SNARE Complexes to Membranes in Fusion

Maximov

Tang

Yang

et al. 2009

Science

318

489

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Trans-SNARE complexes catalyze fast synaptic vesicle fusion and bind complexin, but the function of complexin binding to SNARE complexes remains unclear. Here we show that in neuronal synapses, complexin simultaneously suppressed spontaneous fusion and activated fast Ca 2+ -evoked fusion. The dual function of complexin required SNARE binding, and additionally involved distinct N-terminal sequences of complexin that localize to the point where trans-SNARE complexes insert into the fusing membranes, suggesting that complexin controls the force that trans-SNARE complexes apply onto the fusing membranes. Consistent with this hypothesis, a mutation in the membrane insertion sequence of the v-SNARE synaptobrevin/VAMP phenocopied the complexin loss-of-function state without impairing complexin-binding to SNARE complexes. Thus, complexin probably activates and clamps the force-transfer from assembled trans-SNARE complexes onto fusing membranes.Synaptic vesicle fusion is driven by assembly of trans-SNARE complexes (or SNAREpins) from syntaxin-1 and SNAP-25 on the plasma membrane, and synaptobrevin/ VAMP on the vesicle membrane [1][2][3]. Ca 2+ then triggers fast synchronous synaptic vesicle fusion by binding to the Ca 2+ -sensor synaptotagmin [4][5][6]. Besides SNARE proteins and synaptotagmin, fast Ca 2+ -triggered fusion requires complexin [7]. Complexin is composed of short N-and C-terminal sequences and two central α-helices. Complexin binds to SNARE complexes via its central α-helix, which inserts in an anti-parallel orientation into a groove formed by synaptobrevin/VAMP and syntaxin-1 [8,9]. Although multiple approaches have revealed an essential role of complexin in synaptic fusion [7,[10][11][12][13][14][15], the nature of this role remains unclear. In vertebrate autapses, deletion of complexin selectively impairs fast synchronous neurotransmitter release without changing asynchronous or spontaneous release [7,10]. In in vitro fusion assays, conversely, addition of complexin causes a general block of SNARE-dependent fusion, indicating that complexin is a SNARE clamp [11][12][13][14]. In Drosophila neuromuscular synapses, deletion of complexin produces a >20-fold increase in spontaneous release but only a small decrease in evoked release [15]. Thus, the role of complexin in fusion is unclear. Moreover, even the importance of complexin SNARE- [16,17]. Here we addressed these questions with two complementary approaches -RNAi-dependent knockdown of complexin with rescue, and replacing wild-type synaptobrevin with specific mutants using synaptobrevin knockout (KO) mice [18].We knocked down complexin expression in cultured cortical neurons using an shRNA that targets both complexin-1 and -2, the only complexin isoforms significantly expressed in these neurons [19]. For this purpose, we used lentiviruses that simultaneously synthesize the complexin shRNA and either GFP, wild-type complexin-1, or 4M-mutant complexin-1 that is unable to bind to SNARE complexes (19,20). Lentivirus expressing GFP without the shRNA ...

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Complexins Regulate a Late Step in Ca2+-Dependent Neurotransmitter Release

Cited by 458 publications

References 24 publications

Asymmetric accumulation of hippocampal 7S SNARE complexes occurs regardless of kindling paradigm

Asymmetric accumulation of hippocampal 7S SNARE complexes occurs regardless of kindling paradigm

Cellular distribution and subcellular localization of molecular components of vesicular transmitter release in horizontal cells of rabbit retina

Complexin Controls the Force Transfer from SNARE Complexes to Membranes in Fusion

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